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Cited Publications
ViVitro Labs products are cited in hundreds of peer reviewed publications. Please contact us if you would like to add your publication to our list.
Analysis of thrombosis risk of commissural misaligned transcatheter aortic valve prostheses using particle image velocimetry
Durability of transcatheter aortic valve replacement (TAVR) could be limited by leaflet thrombosis. A commercially available pulse duplicator system (ViVitro Inc., Victoria, BC, Canada) was used to generate physiological flow and pressure conditions of the cardiovascular circulation. Since commissural alignment in TAVR has only recently become the focus of clinical research, there is a clear gap in understanding the long-term clinical impact of commissural alignment.Hydrodynamic ex-vivo analysis of valve sparing techniques: assessment and comparison
This work investigates the impact of the valve-sparing technique on the aortic valve function. The hydrodynamic performance assessment of each implant was conducted in-vitro on a hydro-mechanical pulse duplicator. This shows that, despite providing generally good performance, current valve sparing techniques are still suboptimal and far from matching the physiological leaflets dynamics.Preventing extrinsic mechanisms of bioprosthetic degeneration using polyphenols
This study was to evaluate the impact of a polyphenols-based treatment on the extrinsic mechanisms responsible for early BHV degeneration. The hydrodynamic performance of the polyphenolic-treated and untreated T-GT commercial BHVs was assessed under simulated pulsatile flow in a Vivitro Pulse Duplicator System. The treatment is chemically stable, improves tissue extensibility, and effectively stabilizes glutaraldehyde.Biomechanical evaluation of aortic regurgitation from cusp prolapse using an ex vivo 3D-printed commissure geometric alignment device
Aortic regurgitation (AR) is one of the most common cardiac valvular diseases, and it is frequently caused by cusp prolapse. The simulator contains a programmable pulsatile linear piston pump (ViVitro Superpump, ViVitro Labs) and a viscoelastic impedance adapter (ViVitro) that is comprised of two compliance chambers and a fixed resistance element and generates a physiologic ventricular waveform. In this study, we successfully designed a commissure geometric alignment device that can manipulate aortic commissure positions to induce aortic cusp prolapse.Bioinspired polymeric heart valves derived from polyurethane and natural cellulose fibers
In this work, bioinspired anisotropic polymeric heart valves were fabricated using composite materials from polyurethane (PU) and natural cellulose fiber bundles. The hydrodynamic performance of the polymeric valve was evaluated by the ViVitro Pulse Duplicator system. Our results demonstrate the potential application of bioinspired anisotropic CPU composites as polymeric heart valves.Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing
The aim of this review is to provide an overview on Mock Circulatory Loops and to discuss the recent developments of 3D anatomical models for cardiovascular Medical Device testing. One example is the ViVitro Pulse Duplicator system. The simulator is provided with a flexible ventricular sac activated by a piston pump. The addition of 3D anatomical models enables more realistic connections of the Medical Device with the implantation site and enhances the testing capabilities of the Mock Circulatory Loop.An In Vitro Circulatory Loop Model of the Pediatric Right Ventricular Outflow Tract as a Platform for Valve Evaluation
The aim of this study was to develop a robust in vitro system for quantifying flow conditions after various RVOT interventions. The MCL was developed around the ViVitro Pulse Duplicator System with the viscoelastic impedance adapter and ventricle chamber attachments. The 3D-printed RVOT anatomical model and in vitro pulmonary circulatory loop developed in this work provide platform for planning and evaluating surgical interventions in the pediatric population.Ultrafast Myocardial Principal Strain Ultrasound Elastography during Stress Tests: in vitro Validation and in vivo Feasibility
Assessment of myocardial contractility during a stress test is of high clinical value for the diagnosis and evaluation of cardiovascular diseases, especially coronary disease and heart failure. Both ends of this left-ventricular mimicking phantom (wall thickness of 15 mm) was then connected to polyvinyl chloride tubing by a pair of loosely attached steel clamps to a pulse duplicator (model #SD2001-1, ViVitro systems Inc., Victoria, BC, Canada). The complex, large, and rapid myocardial deformation during stress tests were also accurately imaged by the proposed strain estimator with close agreement with sonomicrometry.A soft robotic sleeve mimicking the haemodynamics and biomechanics of left ventricular pressure overload and aortic stenosis
Advances in soft robotics have led to the development of high-fidelity simulators of pathophysiology for biomedical applications. An MCL was built using a pulsatile pump (SuperPump, ViVitro Labs), an anatomically accurate compliant silicone aortic vessel (E ≈ 1 MPa, United Biologics) connected to two adjustable compliance chambers (that is, ventricular, systemic), and a resistive valve. The models leverage haemodynamic mimicry and may facilitate the development of patient-specific applications. The models could also facilitate the clinical translation of treatments; in particular, a cohort of AS patients could be recapitulated in an in vivo porcine model, and new treatments could be evaluated preclinically.Canary in the cardiac-valve coal mine: Flow velocity and inferred shear during prosthetic valve closure –predictors of blood damage and clotting
To demonstrate a clear link between predicted blood shear forces during valve closure and thrombogenicity that explains the thrombogenic difference between tissue and mechanical valves and provides a practical metric to develop and refine prosthetic valve designs for reduced thrombogenicity. Incorporated as Vivitro Systems Inc (VSI), our primary focus was research, design and development of cardiac valve implant devices and on the laboratory test systems required. In 2009, work transitioned into a separate independent research and development enterprise, ViVitro Laboratories Inc. (VLI). The application of unique technology, rapid prototyping and ranking of flow velocity patterns near valve closure optimized experimental valve geometry for reduced thrombus potential compared with control valves.Timing of Bioprosthetic valve fracture in transcatheter valve-in-valve intervention: impact on valve durability and leaflet integrity
To assess the impact of bioprosthetic valve fracture (BVF) timing on long-term transcatheter heart valve (THV) durability. Valve testing was performed in the ViVitro Labs testing facilities (ViVitro Labs Inc, Victoria, Canada). Hydrodynamic testing was performed using a commercially available pulse duplicator (ViVitro Labs Inc, Victoria, Canada), meeting the equipment requirements defined in ISO 5840-3 for pulsatile flow testing (16) (Figure 1A). In this bench study, the ACn and the S3 showed acceptable hydrodynamic performances after AWT to 200M cycles, equivalent to 5 years, irrespective of BVF timing compared to no fracture.Trileaflet semilunar valve reconstruction: pulsatile in vitro evaluation
We investigated a new surgical technique of trileaflet semilunar valve reconstruction possessing the potential of remaining sufficient and allowing for some growth with the child. Pulsatile flow was produced by a Series piston pump (SuperPump AR; ViVitro Labs, Victoria, Canada), connected to the ventricular chamber. TSVR was achievable in vitro. Hydrodynamic pressure and echocardiographic evaluations demonstrated a sufficient and non-stenotic neo-valve.Impact of Commissural Misalignment on Hydrodynamic Function Following Valve-in-Valve Intervention With the ACURATE neo
The aim of this study was to assess the impact of commissural misalignment (CMA) on hydrodynamic function following VIV intervention with the ACURATE neo THV using a bench model. In VIV using the ACURATE neo THV at deep implantation, increasing degree of CMA was associated with THV leaflet interaction with those of the surgical valve and worsening regurgitant fraction. THV leaflet interaction was prevented when there was CA.Hydrodynamic Performance of a Novel Sutureless Prosthetic Aortic Valve
The aim of the study was an in vitro hydrodynamic study of the developed prosthetic heart valve of the second generation, designed to carry out an implantation using “valve-in-valve” method. ...Prototypes of the developed prosthesis were studied under simulated physiological conditions of the heart using a Vivitro Labs pulse duplicator (Canada) in a comparative aspect with “UniLine” clinical commercial aortic valve bioprosthesis (Russia)... ...The design of the prosthesis under development has shown its consistency in terms of functional characteristics, both in comparison with the original UniLine prosthesis and with literature data....Development of a Modular Tissue Phantom for Evaluating Vascular Access Devices
Central vascular access (CVA) may be critical for trauma care and stabilizing the casualty. However, it requires skilled personnel, often unavailable during remote medical situations and combat casualty care scenarios. Automated CVA medical devices have the potential to make life-saving therapeutics available in these resource-limited scenarios, but they must be properly designed. Unfortunately, currently available tissue phantoms are inadequate for this use, resulting in delayed product development. ...A SuperPump (ViVitro Labs, Victoria, BC, Canada) was used for generating pulsatile, cardiac mimicking arterial flow within the flow loop test platform (Figure 1D)... ...In conclusion, the tissue phantom model presented addresses a current testing gap for developing central vascular access medical devices. Troubleshooting is essential and having to rely on live, or even ex vivo, animal testing for evaluating a medical device with physiological mimicking fluid flow or pressure levels will slow device development...Experimental study of flow structure impact on the fluid parameters in saccular aneurysm models
Aneurysms are abnormal expansion of weakened blood vessels which can be debilitating or fatal upon rupture. Previous studies have shown that hemodynamics play a role in aneurysm formation, growth and rupture. Therefore, the objective of this work is to investigate the impact of flow structures on vortex strength, impinging location, and wall shear stress for two aneurysm models. ...The inflow parameters used in this study, and , were controlled using a ViVitro Labs Inc. SuperPump system... ...The flow evolution results showed that impacted the vortex formation, growth, and dissipation processes for the studied aneurysm model...Design and Preliminary Testing of a Quadleaflet ePTFE Pediatric Prosthetic Heart Valve
The aim of this paper is to: 1) showcase the design process of a quadleaflet ePTFE valved conduit with a diameter of 16mm or less and 2) offer a hemodynamic performance comparison. ...The proposed valve was tested using the ViVitro Pulse Duplicator under physiologic cardiac conditions... ...A comparison between the two ePTFE handmade valves (trileaflet and quadleaflet) demonstrated hemodynamic differences in regurgitation due to leaflet number. The handmade valves both showed increased regurgitation compared to a Carbomedics valve (commercially available design). Regurgitation had varying effects on pressure gradients and cardiac output...Study of Biomechanics of the Heart Valve Leaflet Apparatus Using Numerical Simulation Method
The aim of the study was to study the complex biomechanics of the aortic valve prosthesis and to analyze the effect of frame mobility on the stress-strain state and geometry of the valve leaflet apparatus using a numerical simulation method, which reproduces the qualitative and quantitative results of its bench tests. ...The simulation was validated by comparing the results of numerical and bench simulation on the ViVitro Labs hydrodynamic system (ViVitro Labs Inc., Canada)... ...The results of the UniLine prosthesis biomechanics modeling have demonstrated that mobility of the frame struts of the heart valve prosthesis is a crucial aspect in assessing the effectiveness of the leaflet apparatus geometry and may be a negative factor in case of a highly elastic leaflet material...Modal Decomposition Techniques: Application in Coherent Structures for a Saccular Aneurysm Model
Aneurysms are localized expansions of blood vessels which can be fatal upon rupture. Studies have shown that aneurysm flows exhibit complex flow phenomena which consist of single or multiple vortical structures that move within the flow cycle. ...Rep and α were the inflow parameters used to match and simulate the conditions in the human circulatory system. These inflow parameters were precisely controlled with a ViVitro Labs Inc. SuperPump system... ...Both POD and DMD are capable analysis tools to investigate the spatial and temporal behavior of large-scale structures of a given flow field. POD and DMD can be used to create mathematical models to look into the flow evolution in sufficiently high detail and at any time step...Validating In Silico and In Vitro Patient-Specific Structural and Flow Models with Transcatheter Bicuspid Aortic Valve Replacement Procedure
Bicuspid aortic valve (BAV) is the most common congenital cardiac malformation, which had been treated off-label by transcatheter aortic valve replacement (TAVR) procedure for several years, until its recent approval by the Food and Drug Administration (FDA) and Conformité Européenne (CE) to treat BAVs. ...Materials and Methods Patient-specific in silico models and 3D printed replicas of 3 BAV patients with different degrees of post-TAVR paravalvular leakage (PVL) were created. Patient-specific TAVR device deployment was modeled in silico and in vitro—following … ...PVL degree and locations were consistent with the clinical data. Cross-validation comparing the stent deformation and the flow parameters between the in silico and the in vitro models demonstrated good agreement....The Supera Interwoven Nitinol Stent as a Flow Diverting Device in Popliteal Aneurysms
...To assess this flow diverting strategy for popliteal aneurysms, flow profiles and thrombus formation likelihood were investigated in popliteal aneurysm models... ...The model was placed in a circulating flow set-up with a blood-mimicking fluid (Fig. 3). At the inlet, a hydraulic piston pump (SuperPump, ViVitro labs, Victoria, Canada) was used to enforce time-varying forward flow...Comparison of Flow Behavior in Saccular Aneurysm Models Using Proper Orthogonal Decomposition
...Rep and α were two inflow parameters used in this study, and these were controlled using a ViVitro Labs Inc. (Victoria, BC, Canada) SuperPump system...POD provides a method for analyzing complex flow phenomena in great detail. It can be used to study a variety of unsteady, physiological flows to understand the behavior of energetic flow structures..The Technological Basis of a Balloon-Expandable TAVR System: Non-occlusive Deployment, Anchorage in the Absence of Calcification and Polymer Leaflets
...Hydrodynamic testing to determine gradients (ΔP), effective orifice areas (EOA) and regurgitant fractions was performed in a pulse duplicator (Cardiac Output: 5 L/min; 37°C; 70 bpm; Stroke Volume: 32 ± 5 ml; Systolic Phase Duration of 35 ± 5%) (ViVitro Labs Inc; Victoria, BC, Canada)...The BE TAVR system met all requirements for which it was developed...Ex vivo biomechanical analysis of flexible versus rigid annuloplasty rings in mitral valves using a novel annular dilation system
...The left heart simulator, which has been previously described, features a pulsatile linear piston pump (ViVitro Superpump, ViVitro Labs, Victoria, British Columbia, Canada) to generate physiologic parameters using the pump controller and software (ViVitest Software, ViVitro Labs) programmed in accordance with ISO 5840 standards for in vitro valve testing...The mitral annular dilation system successfully generated an ex vivo mitral annular dilation model with MR...Comprehensive In-Vitro Neurovascular Model Assessment for Implant Simulation
...Physiologically-relevant patient flow parameters were tuned within the system using a Super Pump AR (ViVitro Labs)...This in-vitro aneurysm flow model utilized the latest in UV-cured 3D-printing techniques to provide a realistic simulation of neurovascular tortuosity and aneurysm device delivery...Towards Durability Estimation of Bioprosthetic Heart Valves Via Motion Symmetry Analysis
...Our experimental setup to collect high-quality videos and pressure and velocity data involves tricupsid BHVs mounted in the Pulse Duplicator device from ViVitro Labs...Experiments on four cases that include three different tricuspid BHVs yielded promising results, with the DTW scores showing a good coherence with respect to the simulations...Biomechanical Engineering Analysis of an Acute Papillary Muscle Rupture Disease Model Using an Innovative 3D-Printed Left Heart Simulator
...The severity of acute papillary muscle (PM) rupture varies according to the extent and site of the rupture. However, the haemodynamic effects of different rupture variations are still poorly understood...A 3D printer (Carbon 3D, Redwood City, CA, USA) was used to prototype a modular left heart (left atrium and ventricle) and was mounted to a pulsatile linear piston pump (ViVitro Superpump; ViVitro Labs, Victoria, BC, Canada)...Ex Vivo Model of Ischemic Mitral Regurgitation and Analysis of Adjunctive Papillary Muscle Repair
Driven by a pulsatile linear piston pump (ViVitro Superpump, ViVitro Labs, Victoria, BC, Canada) which generates physiologic hemodynamics in accordance with ISO 5840 in vitro cardiac valve testing standards.Effect of Leaflet Type and Leaflet-Stent Attachment Height on Transcatheter Aortic Valve Leaflet Thrombosis Potential
The physiologic pressures and flows were achieved by adjustment of systemic resistance and compliance elements, and flow driven from a piston pump (Vivitro Labs Inc. Victoria, Canada).Application of Dynamic Mode Decomposition to Study Temporal Flow Behavior in a Saccular Aneurysm
The inflow conditions are precisely controlled using a ViVitro SuperPump system where nondimensional fluid parameters such as peak Reynolds number (Rep) and Womersely number (α) are varied from 50–270 and 2–5, respectively.Echo planar imaging–induced errors in intracardiac 4D flow MRI quantification
A pulsatile hydraulic piston pump (Vivitro Labs, Victoria, Canada) was connected to the tank with semirigid tubing. This pump, positioned outside the scanner room, generated a sinusoidal-like pulsatile waveform with 70-bpm frequency without net flow, resulting in a pressure waveform inside the tank that created contraction of the filled LV phantom with a 300-ms systolic period and 50-mL stroke volume.In Silico Modelling of Aortic Valve Implants – Predicting In Vitro Performance using Finite Element Analysis
...To evaluate the hydrodynamic performance of each valve, in vitro bench testing was performed using a Vivitro Pulse Duplicator (Figure 2a) (Vivitro Labs, Inc. Victoria, B.C.) according to ISO 5840...Papillary Muscle Approximation Reduces Systolic Tethering Forces and Improves Mitral Valve Closure in the Repair of Functional Mitral Regurgitation
...actuating pump with a viscoelastic impedance (Superpump, Vivitro Labs, London, ON) was connected to the LV, and programmed to generate physiological left ventricular pressures. 0.9% saline was used as the working medium in this flow loop...Tricuspid Versus Mitral Performance of Cylindrical Porcine Small Intestinal Submucosa Valves
...hydrodynamic testing of the valves mounted in mitral and tricuspid positions were performed using a pulse duplicator system (ViVitro Labs) using 0.9% saline solution...Mapping of bovine pericardium to enable a standardized acquirement of material for medical implants
… was applied, was documented. 2.9. Durability testing. To investigate the long-term durability, patches were tested in a modified high-cycle (HC) system (HiCycle Durability Tester; ViVitro Labs Inc., Victoria, CAN). A 3D printed …Application of Proper Orthogonal Decomposition to Study Coherent Flow Structures in a Saccular Aneurysm
… vectors in the sac region. 3.3 Pump System. To generate controlled inflow conditions for this study, a piston pump (ViVitro Labs Inc. SuperPump Sys- tem AR Series, Victoria, BC, Canada) was used. The piston pump system …2D PIV experiments of oscillatory flow in a stenosis: A study into the physics of flow of cerebrospinal fluid
...the Vivitro pump, labeled F, (SuperPump, ViVitro labs,Victoria, Canada) was used to create the oscillatory waveform...Computational modelling of flow in the liver vasculature using the Lattice Boltzmann method to study microsphere distribution
...a hydraulic piston pump (SuperPump, ViVitro labs, Victoria, Canada) was used to generate the pulsatile flow and...Simulating Radial Pressure Waveforms with a Mock Circulatory Flow Loop to Characterize Hemodynamic Monitoring Systems
… Pressure measurement location. ºFlow measurement location. Full size image. Deionized water is circulated through the MCL using a piston pump [ViVitro Labs, Victoria, BC, Canada] that is fluid-coupled to a suspended silicone-based mock ventricular sac …Comprehensive in-vitro neurovascular model assessment for implant simulation
...physiologically-relevant patient flow parameters were tuned within the system using a Super Pump AR (ViVitro Labs). A data acquisition system (DAQ) with LabVIEW® software recorded real time pressure and flow waveforms, mean arterial pressures (MAP) and flows through each inlet and outlet branch of the 3D-printed CW model. The flow model included an introducer for microcatheter and device delivery access...Effect of inhalation on oropharynx collapse via flow visualisation
… Fluorescent spherical particles (500-600 µm diameter, Cospheric LLC, Santa Barbara, USA) were injected into the head of a piston-driven SuperPump (Vivitro Labs, Victoria, Canada) that was connected to an …A novel 3D-Printed preferential posterior mitral annular dilation device delineates regurgitation onset threshold in an ex vivo heart simulator
...This work shows the design and implementation of a 3D-printed valve dilation device to preferentially dilate the posterior mitral valve annulus... ...In brief, a custom 3D-printed left heart chamber (Fig. 2A) was mounted to a pulsatile linear piston pump (ViVitro Superpump, ViVitro Labs, Victoria, BC, Canada) with the ability to generate physiologic conditions … ...this annular dilation device provides the means to investigate the design and optimization of novel annuloplasty rings....4-D Echo-Particle Image Velocimetry in a Left Ventricular Phantom
Left ventricular (LV) blood flow is an inherently complex time-varying 3-D phenomenon, where 2-D quantification often ignores the effect of out-of-plane motion. In this study, we describe high frame rate 4-D echocardiographic particle image velocimetry (echo-PIV) using a prototype matrix transesophageal transducer and a dynamic LV phantom for testing the accuracy of echo-PIV in the presence of complex flow patterns.... … 1a). The mitral and aortic tracts of the LV were connected to atrial and compliance chambers (transparent acrylic, built in-house), which were connected via a tube with an adjustable resistance valve (ViVitro Labs … ... We demonstrate that 4-D echo-PIV could be performed in just four heart cycles, which would require only a short breath-hold, providing promising results. However, methods for resolving high velocity gradients in regions of poor spatial resolution are required before clinical translation....Fluid-Structure Interaction Models of Bioprosthetic Heart Valve Dynamics in an Experimental Pulse Duplicator
Computer modeling and simulation (CM&S) is a powerful tool for assessing the performance of medical devices such as bioprosthetic heart valves (BHVs) and promises to accelerate device design and regulation. This study describes work to develop dynamic computer models of BHVs in the aortic test section of an experimental pulse duplicator platform that is used in academia, industry, and regulatory agencies to assess BHV performance... ...This work represents a step towards the experimental validation of this FSI modeling platform for evaluating BHVs.... … In vitro experiments are performed using two different experimental platforms, including a ViVitro Pulse Duplicator (ViVitro Labs, Inc., Victoria, BC, Canada) available through the FDA Cardiac Device Flow Lab and a customized …Bio-inspired anisotropic polymeric heart valves exhibiting valve-like mechanical and hemodynamic behavior
Herein, two types of silk fibroin (SF) fiber membranes with anisotropic (ASF) and isotropic (ISF) properties were prepared by electrospinning, and were further combined with poly(ethylene glycol) diacrylate (PEGDA) hydrogels to serve as polymeric heart valve (PHV) substitutes (PEGDA-ASF and PEGDA-ISF)... ...The PHVs from both PEGDA-ASF and PEGDA-ISF presented appropriate hydrodynamic properties from pulse duplicator tests according to the ISO 5840-3 standard.... ...The Gauss curvature analysis also indicated that the anisotropic PEGDA-ASF valve can produce appropriate surface morphology by dynamically adjusting the movement of bending area during the opening process... … 1c, d). Pulse duplicator tests In vitro hemodynamic properties of PHVs were tested in a 0.9% saline solution using a pulse duplicator system (Vivitro Labs, Inc., British Columbia, Canada) according to the ISO 5840-3 standard [21] …Porcine small intestinal submucosa mitral valve material responses support acute somatic growth
Conceptually, a tissue engineered heart valve (TEHV) would be especially appealing in the pediatric setting since small size and somatic growth constraints would be alleviated. Here, we utilized porcine small intestinal submucosa (PSIS) for valve replacement... … the Dacron tubes housing the PSIS valves were measured in order to secure the valve‐in‐ conduit (Figure 1) in the mitral position within a pulse duplicator system (ViVitro Labs, Victoria, BC) … A pulse duplicator system… ... Our findings suggest that the altered structural responses of PSIS, post-fatigue, rather than de novo tissue formation, are primarily responsible for the valve’s ability to accommodate somatic growth during the acute phase (90 days) following mitral valve replacement...Mitral chordae tendineae force profile characterization using a posterior ventricular anchoring neochordal repair model for mitral regurgitation in a three-dimensional-printed ex vivo left heart simulator
Posterior ventricular anchoring neochordal (PVAN) repair is a non-resectional technique for correcting mitral regurgitation (MR) due to posterior leaflet prolapse, utilizing a single suture anchored in the myocardium behind the leaflet... ...Porcine mitral valves were mounted in a 3-dimensional-printed heart simulator and chordal forces, haemodynamics and echocardiography were collected at baseline, after inducing MR by severing chordae, and after PVAN repair.... ...PVAN repair eliminates MR by positioning the posterior leaflet for coaptation, distributing forces throughout the valve....Implications of hydrodynamic testing to guide sizing of self‐expanding transcatheter heart valves for valve‐in‐valve procedures
...Bench study assessed the hydrodynamic performance of different sizes of self‐expanding supra‐annular THVs in three different surgical aortic bioprostheses at different implantation depths.... ...A small versus medium ACURATE neo (ACn), and a 26 mm versus 29 mm Evolut R were assessed after VIV implantation in 25 mm Mitroflow, Mosaic, and Magna Ease aortic surgical bioprostheses, at three implantation depths (+2 mm, ‐2 mm, and ‐6 mm).... ...Use of a larger self‐expanding THV was associated with superior hydrodynamic performance if the THV was implanted high....Fluid-Structure Interaction Models of an Experimental Pulse Duplicator for Simulating Bioprosthetic Heart Valve Dynamics
This study describes work to develop dynamic computer models of BHVs in the aortic test section of an experimental pulse duplicator platform... ...We compare our numerical simulations to experimental data from two similar pulse duplicators, including a commercial ViVitro system and a custom platform related to the ViVitro pulse duplicator.... ...This work represents a step towards the experimental validation of this FSI modeling platform for evaluating BHVs....Biomechanical modeling and hemorheological assessment of ascending thoracic aortic aneurysm, aortic heart valve, and blood clot
... thesis firstly evaluated the biomechanical contributions to ATAA progression under the influence of anatomy, hypertension, and hematocrit using fully coupled fluid-structure interaction (FSI) with arterial wall anisotropy to provide additional information in patient evaluations... ...The three different ATAA models identified different aortic expansions that were not uniform under pulsatile pressure and a geometry depended on elevated wall stress under hypertension.... ... A commercially available, 23 mm BMHV with a tissue annulus diameter / internal diameter (TAD/ID) of 18.5 mm (Figure 3.2), was used as the test model. ViVitro pulse duplicator was used to assess the performance and function of prosthetic heart valves under simulated cardiac conditions. ...Ventricular vortex loss analysis due to various tricuspid valve repair techniques: an ex vivo study
The deteriorating nature of severe functional tricuspid regurgitation (FTR) has led to the heightened interest in this pathology... ...In this study, the hemodynamics of the right ventricle (RV) after (i) clover edge-to-edge tricuspid repair and (ii) double orifice tricuspid repair was evaluated in three right heart models using an ex vivo pulsatile platform emulating severe FTR with the aid of stereoscopic particle image velocimetry... … circulation (35). A closed ventricular chamber housing the silicon RV model was directly 184 connected to the pulsatile wave-generating piston pump (SuperPump AR series, ViVitro Labs 185 Inc., Victoria, BC, Canada) to …Pulsatile Flow Investigation in Development of Thoracic Aortic Aneurysm: An In-Vitro Validated Fluid Structure Interaction Analysis.
Thoracic aortic aneurysm (TAA) is a severe cardiovascular disease with a high mortality rate, if left untreated... ...In order to gain more insight on TAA formation, we developed a computational framework in vitro to investigate and compare the flow patterns between pre-aneurismal and post-aneurismal aorta using a deformable wall model... ...The pulsatile flow was created using a piston pump (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada) generating the inlet velocity profile with the How rate of 4 L/min at the frequency of 1 Hz, extracted from the literature …Aortic Valve Leaflet Curvature as a Function of Elastin Degradation
... Aortic valve calcification (AVC) is caused by defects in the valves and it is a health condition which usually requires surgical valve replacement... ...The proposed project aims to capture images of the aortic leaflet curvature while cyclic flexure is conducted... The curvature of the leaflets will be captured using two high-frame rate video systems. The aortic valve leaflet flexure experiments will be produced using a Vivitro Pulse Duplicator (Vivitro Labs Inc. Victoria, BC, Canada) …E-021 In vitro neurovascular model development for liquid embolic implant simulation
Although current microcatheter technologies have advanced in recent years, corresponding endovascular devices still lag behind... ...This research project includes development of innovative in vitro aneurysm vessel model with complex side branching.... … communicating (ACA) bifurcation. Flow is regulated through the use of a Super Pump AR (ViVitro Labs). This 3D printed model will be implemented in an in vitro flow model that enables systemic data collection. A data acquisition … ...The in vitro model is used to simulate and quantify short-and long-term viability of new biomaterials for brain aneurysm embolization...An Evaluation of the Influence of Coronary Flow on Transcatheter Heart Valve Neo-Sinus Flow Stasis
Transcatheter heart valve (THV) leaflet thrombosis in the neo-sinus and associated reduced leaflet motion is of clinical concern due to risks of embolism and worsened valve hemodynamics... ...We tested two replicas of FDA approved commercial THVs—intra-annular and supra-annular (similar to the SAPIEN 3 and CoreValve families)—in a left heart simulator with coronary flow... … The Georgia Tech left heart simulator is shown in Fig. 2a. The main flow rate was driven by the primary piston pump (Vivitro Labs Inc. Victoria, Canada); wall-tapped pressure transducers (Deltran DPT-200, Utah Medical Products IncBioinspired Heart Valve Prosthesis Made by Silicone Additive Manufacturing
Synthetic implants made by traditional fabrication routes are not patient specific and rarely match the performance of their biological counterparts. We present an additive manufacturing approach for the digital fabrication of tissue-like aortic heart valves featuring customizable geometry and leaflet architectures that resemble those of native valve tissue... ...Flow was driven by a forward pressure of 100 mmHg imposed across the valve using a pulsatile testing machine (PD2010; ViVitro, Victoria, BC, Canada)... ...The ability to fabricate synthetic implants with tailored designs at multiple length scales is a key contribution toward the digital fabrication of functional implants that perform on par with native body parts...In-Vitro Pulsatile Flow Testing of Prosthetic Heart Valves: A Round-Robin Study by the ISO Cardiac Valves Working Group
...A round-robin study carried out in 2005 in accordance with ISO 5840:2005 revealed significant variabilities in prosthetic heart valve hydrodynamic performance measurements among the participating laboratories. In order to re-examine the inter-laboratory variability based on the “state-of-the-art” under ISO 5840-1 and 5840-2:2015, the ISO Cardiac Valve Working Groups decided in 2016 to repeat the round-robin study.... … took part in the round-robin study, including one academic laboratory (Helmholtz Institute of the RWTH University, Aachen, Germany), three testing service providers (BDC Laboratories, Wheat Ridge, CO; Medical Implant …Development and ex vivo validation of novel force-sensing neochordae for measuring chordae tendineae tension in the mitral valve apparatus using optical fibers with embedded Bragg gratings
Few technologies exist that can provide quantitative data on forces within the mitral valve apparatus... Using FBG sensors, we created a force-sensing neochord that mimics the natural shape and movement of native chordae.... … Redwood City, CA, USA) was mounted to a programmable pulsatile linear piston pump (ViVitro Superpump, ViVitro Labs, Victoria, BC, Canada) with the ability to generate physiologic conditions using the pump controller and …Performance Analysis of the Transcatheter Aortic Valve Implantation (TAVI) on Blood Flow Hemodynamics: An Optical Imaging‐based In Vitro Study
...In this study, we aimed at investigating the impact of transcatheter aortic valve implantation (TAVI) devices on blood flow patterns that develop in the ascending aorta under physiological flow conditions in vitro... … Graphics, Heidelberg, Germany). Valve hydrodynamics A Pulse Duplicator System (ViVitro Labs Inc) was used for the assessment of heart valve performance and function under simulated cardiac conditions. The system is a … ...We conclude that the characteristics and material designs of TAVI devices have strong influences on the hemodynamics in the ascending aorta...The influence of hematocrit on the hemodynamics of artificial heart valve using fluid-structure interaction analysis
...the objective of this study is to analyze the hemodynamics and valve mechanics of a bileaflet mechanical heart valve and investigate the hemorheological characteristics under the change of hematocrit.... … Fig. 2. Schematic illustrating DPIV test set-up used in the current experiment (Image courtesy of ViVitro Labs Inc.). To simulate the physiological flow conditions, an acrylic test chamber, that represented a simplified model of … ...The current numerical analysis revealed the hematocrit influenced the shear stress distributions over a cardiac cycle...In vitro assessment of pacing as therapy for aortic regurgitation
Clinical evaluation of pacing therapy in mitigating the aortic insufficiency after transchateter aortic valve implantation often gives contradictory outcomes... ...A series of in vitro tests reproducing the heart operating changes clinically obtained by pacing was carried out in a 26 mm Edwards Sapien XT prosthesis with mild paravalvular leakage. The effect of pacing on the regurgitant volumes per cycle and per minute was quantified, and the energy and power consumed by the left ventricle were calculated... … Following well-developed methodologies for evaluation of cardiovascular devices and in vitro haemodynamics features,14 15 physiological pulsatile flow conditions were replicated in a hydromechanical pulse duplicator …Effect of stent crimping on calcification of transcatheter aortic valves
...The goal of this study was to test whether stent crimping increases the risk for early calcification.... … MA, USA). The durability experiment was performed using a standard accelerated wear test (AWT) system (HiCycle Durability Tester, ViVitro Inc., Victoria, BC, Canada) that can ac- commodate up to 6 heart valves. Among the …Direct Ex Vivo Measurement of the Real Geometric Orifice Area to Assess the Hemodynamic Performance of Bioprosthetic Heart Valves
...the debate about the clinical evidence of the so-called patient-prosthesis mismatch (PPM) arose again. In this context it was discussed which valve specific parameter has the biggest evidence for the PPM and therefore the geometric orifice area (GOA) was pointed out as an important factor... …Methods: Commercially available surgical aortic bioprosthetic heart valves from different manufacturers were tested in a FDA / DIN conform Pulse Duplicator System (ViVitro Labs Inc., Victoria, Canada). The system … ...it was clearly demonstrated, that this GOA is a dynamic process over the whole ejection period, which significantly differed from the maximum reached GOA...Hemodynamic Analysis of a Novel Stent Graft Design with Slit Perforations in Thoracic Aortic Aneurysm
Thoracic endovascular aortic repair (TEVAR) has been introduced as a less invasive approach to the treatment of thoracic aortic aneurysm (TAA). However, the effectiveness of TEVAR in the treatment of TAA is often limited due to the complex anatomy of aortic arch... ...This study proposes a novel stent graft design with slit perforations that can positively alter the hemodynamics at the aortic arch while maintaining blood flow to supra-aortic branches... … flow preservation at side branches. The system was driven by a pulse generator (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada) at a flow rate of 5 L/min and a pulse rate of 1 Hz. The reservoir level and mechanical …In-vitro and in-vivo evaluation of a novel bioprosthetic pulmonary valve for use in congenital heart surgery
Management of congenital malformations of the pulmonary artery and valve can be challenging. The severity often demands early intervention, which is rarely definitive due to the natural growth and multiple surgeries may be required... ...In this study, a simple valve design supported by an absorbable proximal stabilization ring is evaluated both in-vitro and in-vivo... … In-vitro model and testing. All in-vitro testing was carried out in a pulsatile flow model using water as the test fluid (Fig. 2). Pulsatile flow and pressure were generated with an electromechanical piston pump (VSI Superpump, Vivitro Labs, Victoria, Canada) …Valve-in-Valve Transcatheter Aortic Valve Replacement and Bioprosthetic Valve Fracture Comparing Different Transcatheter Heart Valve Designs
The authors assessed the effect of valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) followed by bioprosthetic valve fracture (BVF), testing different transcatheter heart valve (THV) designs in an ex vivo bench study... ...The authors assessed the effect of valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) followed by bioprosthetic valve fracture (BVF), testing different transcatheter heart valve (THV) designs in an ex vivo bench study....Stiffness Evaluation of Aortic Aneurysms Using an Ultrafast Principal Strain Estimator: In Vitro Validation
Aortic stiffness is altered by cardiovascular diseases and exacerbated in innate or pathological conditions, which might be detected by noninvasive vascular elastography.... ...results suggest that the proposed model could detect and evaluate aortic aneurysm stiffness and may be useful clinically for the early and timely detection of degraded mechanical properties to impact patient outcomes.... … Hz. Normal and aneurysm aortic deformations were compared by pulsing mimicing vessels at 60 bpm, using a hydraulic pulse duplicator within a left ventricular model (Superpump system, Vivitro Inc., Victoria, BC, Canada) …Bioprosthetic Valves with a Novel Support System with Heart Shape Commissural Posts
Continuous improvement in the mechanics, preservation and anticalcification treatment made bioprostheses the standard mode of valve replacement in the aging population. A novel Support System with large openings at the Commissural posts has been developed and the performance and durability of bioprostheses constructed went under evaluation. … Heart valve pulse duplicator. A heart valve pulse duplicator Vivitro SPS3891 (Vivitro Systems Inc., Victoria, BC Canada) was used to measure hemodynamic parameters. All tests were performed with the standard FDA waveform …Dilation of tricuspid valve annulus immediately after rupture of chordae tendineae in ex-vivo porcine hearts
Chordae rupture is one of the main lesions observed in traumatic heart events that might lead to severe tricuspid valve (TV) regurgitation... ...we investigated the changes on TV geometry, mechanics, and function of ex-vivo porcine hearts following chordae rupture... … The schematic of this apparatus is shown in Fig 1. In short, a positive displacement pump (SuperPump AR Series, Vivitro Labs, Inc., Victoria, BC, Canada) was utilized to induce passive beating in porcine hearts …The application of biomimicry to a mechanical valve design for the abatement of flow instabilities
Studies have suggested that the anterior leaflet of the native mitral valve aid in the formation of an asymmetric vortex ring similar to that seen in healthy left ventricles... ...we seek to investigate if this physiological left ventricular vortex can be replicated solely by the inclusion of an “anterior leaflet-like” feature within a mechanical valve design and its subsequent effects on downstream turbulence.... ...Situated within the working chamber was the left ventricular silicon phantom actuated by a pulsatile pump (ViVitro Labs Inc., Victoria, BC), the resulting ventricular pumping motion circulated a mixture of glycerin and water (40 …Cardiac Valve Bioreactor for Physiological Conditioning and Hydrodynamic Performance Assessment
Tissue engineered heart valves (TEHV) are being investigated to address the limitations of currently available valve prostheses... ...A bioreactor system was designed based on the Windkessel approach. Novel features including a purpose-built valve chamber and pressure feedback control were incorporated to maintain asepsis while achieving a range of hydrodynamic conditions.... … The bioreactor was used to assess the hydrodynamic performance of a bioprosthesis and the results were compared to those obtained with a ViVitro Pulse Duplicator system (ViVitro Labs, Victoria, BC, Canada)... ...The bioreactor system was able to produce a range of pressure and flow conditions from static to resting adult left ventricular outflow tract to pathological including hypertension...Novel transcatheter aortic heart valves exhibiting excellent hemodynamic performance and low-fouling property
Transcatheter aortic heart valves (TAHVs) have been widely used for aortic valve replacements, with less trauma and lower clinical risk compared with traditional surgical heart valve replacements. In the present study, composites of poly(ethylene glycol) diacrylate (PEGDA) hydrogels and anisotropic high-shrinkage polyethylene terephthalate/polyamide6 (PET-PA6) fabric (PEGDA/PET-PA6) were fabricated as artificial heart valve leaflets... … 2.6. Pulse duplicator test. Hemodynamic performance of the TAHVs was assessed using a pulse duplicator system (ViVitro Labs, British Columbia, Canada) under physiological conditions according to ISO 5840-3 standards [21] …Synthetic Aperture Cardiac Imaging with Reduced Number of Acquisition Channels. A Feasibility Study
Commercially available cardiac scanners use 64–128 elements phased-array (PA) probes and classical delay-and-sum beamforming to reconstruct a sector B-mode image... ...The goal of this study was to show the feasibility of reducing the channel count in the diverging wave synthetic aperture image reconstruction method for phased-arrays.... … a water tank with dedicated absorbers at- tenuating the reflected waves (Aptflex F28 and Aptflex F28P, Precision Acoustics, UK), tubing system, wind- kessel (to reduce/eliminate phantom vibrations), Viv- itro Superpump …Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study
Transcatheter aortic valve replacement (TAVR) is a minimally-invasive approach for treating severe aortic stenosis. All clinically-used TAVR valves to date utilize chemically-fixed xenograft as the leaflet material... ... this study, we experimentally evaluated the hemodynamic performance of the valve and compared its performance to clinically-used valves: a gold standard surgical tissue valve, and a TAVR valve.... … Testing was performed in a Vivitro Pulse Duplicator (Vivitro Labs, Victoria, BC) at average Cardiac Out- puts (CO) of 4, 5, 6, and 7 L/min, Heart Rate (HR) of 70bpm, systole-diastole ratio of 0.35–0.65, aortic pressure of …Overexpansion of the SAPIEN 3 Transcatheter Heart Valve
Objectives This study assessed the effect of overexpansion beyond labeled size (diameter) of transcatheter heart valves through an ex vivo bench study... Background Transcatheter heart valves function optimally when expanded to specific dimensions. However, clinicians may sometimes wish to overexpand balloon-expandable valves to address specific clinical challenges. The implications of overexpansion have assumed considerable importance, and objective information to guide practice is limited...Impact of simulated MitraClip on forward flow obstruction in the setting of mitral leaflet tethering: An in vitro investigatio
...Leaflet tethering commonly seen in functional mitral regurgitation may be a significant factor affecting the severity of MS after MitraClip implantation... … conditions. A piston pump (Vivitro Labs Inc. Victoria, Canada) drove physiological left heart flow within the simulator, while an electromagnetic flow probe (Carolina Medical Electronics, East Bend, NC) measured cardiac output (CO) …Two-dimensional affine model-based estimators for principal strain vascular ultrasound elastography with compound plane wave and transverse oscillation beamforming
Polar strain (radial and circumferential) estimations can suffer from artifacts because the center of a nonsymmetrical carotid atherosclerotic artery, defining the coordinate system in cross-sectional view, can be misregistered... ...Two-affine model-based estimators for vascular ultrasound elastography in cross-sectional view of the artery are evaluated in a common framework of high-frame-rate imaging... ...This paper presents two affine model-based estimators, the affine phase-based estimator (APBE) developed in the framework of transverse oscillation (TO) beamforming, and the Lagrangian speckle model estimator (LSME)...Personalized dynamic phantom of the right and left ventricles based on patient-specific anatomy for echocardiography studies — Preliminary results
This work aims to create a dynamic, ultrasound-compatible, realistic and flexible phantom of the left and right ventricles, with application in the diagnosis, planning, treatment and training in the cardiovascular field for studies using echocardiography. … the real tissues. Then, a commercial available computed-controlled dynamic piston pump (Vivitro Labs, Victoria, British Columbia, Canada) was used to pump water... into the model and consequently deform it. This pump systemExperimental study on impact of inflow conditions on large-scale flow structures in an aneurysm
...This study focuses on investigating the hemodynamics inside an aneurysm for different inflow conditions and varying geometrical shapes. ... … precisely controlled. Re and α were varied between 50-250 and 2-5, respectively. A ViVitro Labs pump system was used to pump the fluid and Particle Image Velocimetry (PIV) was used to perform velocity measurements. The flow …A Semi-Stented and Chorded Mitral Valve Prosthesis: Design and Method of Chordal Setting and In Vitro Testing
Mitral subvalvular apparatus plays an important role in mitral and ventricular dynamics by preserving annuloventricular continuity, known to be fundamental for ventricular function... ...We address these issues through the design of a novel semistented and chorded mitral valve that better mimics the native mitral annulus, leaflets and chordae function and can be made from off-the-shelf biomaterials with the potential to be implanted percutaneously... … Pulse duplicator setup We performed hydrodynamic testing in the mitral position on a hydro-mechanical pulse duplicator system (Vivitro Superpump System SP3891, Vivitro, Victoria, BC, Canada), described elsewhere [4]. We used a 25mm Sorin Bicarbon bileaflet …Impact of Clinically Relevant Elliptical Deformations on the Damage Patterns of Sagging and Stretched Leaflets in a Bioprosthetic Heart Valve
After implantation of a transcatheter bioprosthetic heart valve its original circular circumference may become distorted, which can lead to changes in leaflet coaptation and leaflets that are stretched or sagging.... … Valve hydrodynamic performance data were collected using a commercially available left heart Pulse Duplicator (Vivitro Systems) at 0, 41, 80, and 123 M cycles; at these intervals, the valves mounted in the metallic adapter …Evaluating the impact of air compliance chamber volumes on valve performance for three different heart valves
...The air volume shifts the pressure and flow rate waveforms in time and impact the physical operating conditions of the valves with constant input settings in the ViVitest software... … Results obtained from current pulse duplicators are subject to the setup and physical testing settings. The ViVitro Pulse Duplicator from ViVitroLabs Inc … Three different valves were tested in a ViVitro pulse duplicator where...In Vitro Evaluation of Hemodynamic Performance for Right Ventricular Outflow Tract RVOT Reconstruction with Trileaflet ePTFE Valved Conduit
...Percutaneous pulmonary valve implantation (PPVI) has evolved as most exciting development surgical strategy with dysfunctional right ventricle-pulmonary artery conduits. ... ...The purpose of this study is to investigate the hemodynamic and functional consequences of the new design using a mock circulation system... … vasculature. Blood pressures and flows are driven by a digitally controlled hydraulic piston pump (ViViTro Labs Inc., Super Pump System, Victor, BC) to produce pulsatile waves with heart rates of 60 and 80 beats/min from ARV to ARA …Assistive technology using regurgitation fraction and fractional-order integration to assess pulmonary valve insufficiency for pre-surgery decision making and post-surgery outcome evaluation
...This study proposes an assistive technology to quantify regurgitation using the regurgitation fraction (RF) and heart pump efficiency (HPE). … pulmonary valves. The blood pressure and flow were driven by a digitally controlled hydraulic piston pump (ViViTro Labs Inc., Super Pump System, Victor, BC) to produce pulsatile waves with heart rates of 60 and 80 beats/min. The …Over‐expansion of balloon‐expandable transcatheter heart valves
Transcatheter aortic valve implantation can be successful in selected patients with annuli beyond the current recommended limits for available transcatheter heart valves.… Hopefully in future we will have both a broader understanding and a broader range of options. Conflict of interest. Dr. Webb is a consultant to Edwards Lifesciences and ViVitro Labs. Publication cover image. Volume 91, Issue 6. May 1, 2018. Pages 1157-1158Transvalvular pressure gradients for different methods of mitral valve repair: only neochordoplasty achieves native valve gradients
Many surgical and interventional methods are available to restore patency for patients with degenerative severe mitral valve regurgitation... ...Eight porcine mitral valves were tested under pulsatile flow conditions in an in vitro pulsatile flow loop for haemodynamic quantification.... ...All surgical reconstruction techniques were able to sufficiently correct the acute mitral valve regurgitation.... ...The LV chamber was actuated using a computer-controlled piston pump (ViVitro Systems Inc., Victoria, Canada) attached to the LV chamber...Can bioprosthetic valve thrombosis be promoted by aortic root morphology? An in vitro study
Bioprosthetic valve thrombosis has been considered uncommon, but recent studies have shown that it is more frequent than previously thought. ...Two compliant aortic root phantoms with different morphologies (symmetrical and patient-specific) were fabricated with silicone. A bioprosthetic aortic valve was inserted in both phantoms.... ...Blood flow in the aortic root and the washout of the sinus portion are significantly affected by aortic root morphology.... ...The flow loop was actuated by a piston pump (ViVitro Systems Inc., Victoria, BC, Canada)...Development of a validation instrument in myocardial perfusion imaging: results of first flow experiments
...Myocardial perfusion imaging (MPI) is a commonly used diagnostic method in coronary artery disease (CAD)... ... In line with proper clinical decision-making, it is essential to assess institutional MPI test validity by confronting MBF assessment to a ground truth. Our research focuses on developing such validation instrument/method for MPI by means of simulating controlled myocardial perfusion in a phantom flow setup.... … All the data presented in this paper were obtained with the open circuit setup to prevent contrast recirculation. The used piston pump (Vivitro Superpump, Vivitro Labs, Victoria, Canada) generates programmable pulsatile flowSingle calibration multiplane stereo-PIV: the effect of mitral valve orientation on three-dimensional flow in a left ventricle model
...The effects of the orientation of a prosthetic mitral valve in anatomical and anti-anatomical configurations have been investigated during the diastolic filling time... … A commercially available cardiovascular simulator (Vivitro Systems, Inc., Victoria, BC, Canada) that can impose and monitor different physiological pressure and flow conditions was adopted. The hydraulic piston pump was connected to the inner tank …Flow visualization of the non-parallel jet-vortex interaction
...The objective of this study was to characterize three distinct orientations (30°, 60° and 90°) of the non-parallel jet–vortex interaction in a simplified flow loop... … 1 Experimental setup of jet–vortex interaction flow loop. A programmable pulsatile pump (ViVitro SuperPump) allowed for controlled, isolated vortex rings to be ejected into the chamber, as shown in Fig. 2. The flow profile for vortex ring ejection is shown in Fig …Comparative Fluid-Structure Interaction Analysis of Polymeric Transcatheter and Surgical Aortic Valves' Hemodynamics and Structural Mechanics
...All currently FDA-approved TAVR devices use tissue valves that were adapted to but not specifically designed for TAVR use. Emerging clinical evidence indicates that these valves may get damaged during crimping and deployment- leading to valvular calcification, thrombotic complications, and limited durability... ...Our research group has developed a novel polymeric prosthetic valve, which was optimized to reduce stresses on the leaflets, improve hemodynamics and has thrombogenic performance similar to that of a tissue valve... … The valves are then sutured to a nitinol stent for completion of the process. The valves' durability is now being assessed using a Vivitro Hi-Cycle System (Vivitro Labs, Inc … Hydrodynamic performance is being evaluated using the Vivitro left heart simulator (Vivitro Labs, Inc …Experimental Investigation of Left Ventricular Flow Patterns After Percutaneous Edge‐to‐Edge Mitral Valve Repair
This in vitro study aims to evaluate the hemodynamic modifications following a simulated PEtER. A custom-made mitral valve was developed, and two configurations were tested: (i) a single-orifice valve with mitral regurgitation and (ii) a double-orifice mitral valve configuration following PEtER. … MATERIALS AND METHODS In vitro model For the purpose of this study, a ViVitro pulse duplicator (ViVitro Labs, Victoria, BC, Canada) was used (Fig. 1). This system is capable of reproducing physiological flow and pressure waveforms in left heart cavity models …Hemodynamic assessment of extra-cardiac tricuspid valves using particle image velocimetry
...The study utilises both 2-D and 3-D particle image velocimetry (PIV) to interrogate the flow patterns in the vicinity of the extra-cardiac tricuspid valves in an in vitro physiological flow loop, specifically at four measurement locations in the cavo-atrial anatomy. ... ... of the hepatic vein. In contrast, the SVC valve was fully implanted in the SVC. The mock circulatory system was driven by a pulse generator (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada). It comprised of an ultrasonic ...Application of Dynamic Mode Decomposition: Temporal Evolution of Flow Structures in an Aneurysm
...The objective of this study is to identify the large-scale structures in the aneurysm, study temporal behavior, and quantify their interaction with the inflow condition. ... ... For this purpose, detailed Particle Image Velocimetry (PIV) measurements were performed at the center plane of an idealized aneurysm model for a range of inflow conditions. Inflow conditions were precisely controlled using a ViVitro SuperPump system. ...Impact of Inflow Conditions on Coherent Structures in an Aneurysm
...Studies have shown that hemodynamics is integral to developing an understanding of aneurysm formation, growth, and rupture. This investigation focuses on a comprehensive study of the impact of varying inflow conditions and aneurysm shapes on spatial and temporal behavior of flow parameters and structures in an aneurysm.... ... For this purpose, detailed Particle Image Velocimetry (PIV) measurements were performed at the center plane of an idealized aneurysm model for a range of inflow conditions. Inflow conditions were precisely controlled using a ViVitro SuperPump system. ...Applicability of the handmade ePTFE trileaflet-valved conduits for pulmonary valve reconstruction: An ex vivo and in vivo study
...The current study investigated: (i) the function of the ePTFE trileaflet-valved conduits in an ex vivo experimental system and (ii) the short-term performance of the conduit in a porcine model to verify their clinical applicability.... ... valves. 168 Right ventricular function was simulated by using a digitally controlled hydraulic piston 169 SuperPump (ViViTro Labs, Victor, British Columbia, Canada), which generated a pulsating 170 flow to drive the chamber and send it into a compliant pulmonary artery. ...In vitro biomechanical and hydrodynamic characterisation of decellularised human pulmonary and aortic roots
The use of decellularised biological heart valves in the replacement of damaged heart valves ... ...The purpose of this study was to assess the effect of low concentration sodium dodecyl sulphate decellularisation on the in vitro biomechanical and hydrodynamic properties of cryopreserved human aortic and pulmonary roots.... ... performance of the valve roots. A viscoelastic impedance adapter (VIA; Vivitro System Inc., Victoria BC, Canada) was used to deliver a more physiological ventricle pressure and flow waveform in the simulator. This system allowed for ...In-Vitro Pulsatile Flow Measurement in Prosthetic Heart Valves: An Inter-Laboratory Comparison
One of the first steps in qualifying a new prosthetic valve for eventual clinical use is preclinical flow performance testing in vitro... ...This collaborative effort between heart valve manufacturers and the Food and Drug Administration (FDA) was designed to evaluate the variability of the pulse duplicator test technology for pulsatile flow performance measurement in an interlaboratory round robin... ...A commercially available duplicator, the Vivitro system (Vivitro, Inc., Vancouver, Canada), was used at two centers. The design specifications are summarized in Table I....Experimental Study of Right Ventricular Hemodynamics After Tricuspid Valve Replacement Therapies to Treat Tricuspid Regurgitation
The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR)... ...In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated... ... A closed ventricular chamber housing the silicon RV model was connected to a closed atrial chamber at one end, and was directly connected to the pulsatile wave-generating piston pump (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada) at the other end to simu ...in-vitro Assessment of Expanded-Polytetrafluoroethylene Stentless Tri-leaflet Valve Prosthesis for Aortic Valve Replacement
Truly stentless polymeric valve prosthesis can be a viable alternative for aortic valve replacement (AVR). In the present paper, the dynamic and hemodynamic performance of a novel designed expanded-polytetrafluoroethylene (ePTFE) stentless tri-leaflet valve was assessed experimentally.... ... The in-vitro tests were performed under time-varying physiological pressure by using the Vivitro pulse duplicator. ... The Vivitro pulse duplicator (Vivitro Systems Inc., Victoria, BC, Canada) was used to generate the physiological pressure and flow in the left ventricle and aorta. ...A correlation between long-term in vitro dynamic calcification and abnormal flow patterns past bioprosthetic heart valves
In this paper, a long-term in vitro dynamic calcification of three porcine aortic heart valves was investigated using a combined approach that involved accelerated wear testing of the valves in the rapid calcification solution, hydrodynamic assessment of the progressive change of effective orifice area (EOA) along with the transaortic pressure gradient, and quantitative visualization of the flow. ...ViVitro Labs Inc. for providing access to their facility and equipment for this study. Compliance with ethical standards Conflict of interest Oleksandr Barannyk has been a postdoctoral fellow at ViVitro Labs Inc. under MITACS...Leaflet Free Edge Detection for the Automatic Analysis of Prosthetic Heart Valve Opening and Closing Motion Patterns from High Speed Video Recordings
...The valve orifi ce area over time, which informs on the opening and closing motion patterns, constitutes a key quality metric for PHV assessment... ...In this paper, we propose a novel orifi ce segmentation approach for automatic prosthetic heart valves quantitative performance analysis, based on the detection of the leaflet free edges to accurately extract the actual orifi ce area.An improved implementation of block matching for motion estimation in ultrasound imaging
Ultrasound elastography has become an important procedure that provides information about the tissue dynamics and may help on the detection of tissue abnormalities. We propose a novel algorithm to perform speckle tracking, which consists in an implementation of 2D Block Matching with two enhancements: sub-pixel linear interpolation and displacement propagation, which are able to increase resolution, reduce computation time and prevent kernel mismatching errors. ... studies on their numerical analogs. Fig. 1 Section of the f20dX LV phantom. Dimensions in [mm]. METHODS Fig. 2 Experimental setup. 1 – GE Vivid 6 scanner; 2 – water tank; 3 – LV model; 4 – M4S-RS probe; 5 – windkessel; 6 – Vivitro Superpump; 7 – Pump Controller; 8 – PC. ...In-vitro investigation of coronary atherosclerosis on a modified vivitro system
Coronary heart disease (CHD) is a common cardiac disorder in which a portion of the coronary artery is blocked, leading to a potential heart attack. Timely and accurate evaluation of suspected CHD patients is critical. Computer Tomography Angiography (CTA)... In order to streamline the evaluation of suspected CHD patients, we propose to create a more accurate and consistent diagnostic method of interpreting CTA results.In-vitro hemodynamic testing of stentless prosthetic aortic valves
...Mechanical valves usually made from metal and fabrics are very durable but they have poor hemodynamic and are thrombogenic requiring permanent anticoagulation. Tissue heart valves constructed from biological tissues have excellent hemodynamic blood flow, but they lack durability. The project proposed a new valve design that is similar to a stentless tissue valve but made from a synthetic material, Polytetrafluoroethylene (PTFE)... The scope of this project includes designing a fixture to accommodate the valves in the ViVitro System and studying hemodynamic parameters such as pressure drop, flow rate, and dynamic leaflet behaviour of the valves. ...JetValve: Rapid manufacturing of biohybrid scaffolds for biomimetic heart valve replacement
Tissue engineered scaffolds have emerged as a promising solution for heart valve replacement because of their potential for regeneration. However, traditional heart valve tissue engineering has relied on resource-intensive, cell-based manufacturing, which increases cost and hinders clinical translation. ...We demonstrated controlled modulation of these scaffold parameters and show initial biocompatibility and functionality in vitro...Design, Analysis and Testing of a Novel Mitral Valve for Transcatheter Implantation Authors Authors and affiliations
Mitral regurgitation is a common mitral valve dysfunction which may lead to heart failure. This paper presents the design, development and hydrodynamic assessment of a novel bi-leaflet mitral valve suitable for transcatheter implantation. ... animal models. Hydrodynamic Tests. The hydrodynamic performances of the three valve prototypes were assessed on a hydro-mechanical cardiovascular pulse duplicator system (ViVitro Superpump SP3891, ViVitro, BC) (Fig. 3 ...An In Vitro Feasibility Study of the Influence of Configurations and Leaflet Thickness on the Hydrodynamics of Deformed Transcatheter Aortic Valve
Clinically, the percutaneous transcatheter aortic valve (TAV) has been reported to be deformed in a noncircular configuration after its implant. The deformation is universal and various, and it leads to serious leakage and durability problems. ...the present study investigated the effects of the aortic annulus deformation and the leaflet tissue thickness on the hydrodynamics of the TAV. ... Hydrodynamic testing. The TAVs were tested in a quasi-physiological artery pulsatile flow duplicator system, which was custom remoulded to adapt the testing of deformed TAV from commercially available pulse duplicator (Pulse Duplicator; Vivitro Labs, Victoria, BC, Canada.). ...Hydrodynamic Assessment of Aortic Valves Prepared from Porcine Small Intestinal Submucosa
...Assess the functional effectiveness of tri-leaflet PSIS bioscaffolds in the aortic position compared to standard tri-leaflet porcine bioprosthetic valves... ... (b) Pulse duplicator system (Vivitro Laboratories) used for the hydrodynamic evaluation of the valves. ... System calibration, pump control, data collection and analysis are all computer-controlled via software (Vivitest, Vivitro Labs). ...A Tri-Leaflet Nitinol Mesh Scaffold for Engineering Heart Valves
...The main problem with the tissue engineered heart valves is their progressive deterioration that leads to regurgitation and/or leaflet thickening a few months after implantation... ...The current work aims to study the effects of the design features on mechanical characteristics of this valve scaffold to attain proper function prior to in vivo implantation. ... The heart flow simulator system was adjusted for left ventricular pressure waveform with diastolic/systolic pressures of 80/120 mmHg produced by a hydraulic pump system (Superpump system, VSI, SPS3891, Vivitro systems Inc., Victoria, BC, Canada).10 The scaffolds were ...Pledget-Armed Sutures Affect the Haemodynamic Performance of Biologic Aortic Valve Substitutes: A Preliminary Experimental and Computational Study
...Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow rapid implantation, therefore reducing the duration and invasiveness of the intervention. ...The results showed how the performance of cardiac valve substitutes is negatively affected by the presence of pledget-armed sutures... ...The measurements were collected during ten cardiac cycles and analysed in the VSI software pack- age (VSI, ViVitro, Victoria, BC, Canada). The leaflets kinematics were visualised using a high-speed camera. For ...The Impact of Intimal Tear Location and Partial False Lumen Thrombosis in Acute Type B Aortic Dissection
Partial false lumen (FL) thrombosis is a risk factor for long-term mortality in acute type B aortic dissection (ATBAD). This study investigates FL pressures in models of ATBAD with patent and partially thrombosed FL... ...A programmable pulsatile pump (SuperPump; ViVitro Systems, Victoria, BC, Canada) was connected to the left ventricle through a cannula inserted into the apex... ...In a biologic model of ATBAD, the number, location, and FL thrombosis status determine FL pressure. In the setting of partial FL thrombosis, the FL pressure is reduced with proximal tear occlusion and increased with distal tear occlusion. Reduced FL pressure is related to retrograde flow...A calcified polymeric valve for valve-in-valve applications
...developed a novel polymeric valve whose leaflets possess calcium hydroxyapatite inclusions immersed in them. This study reports the characteristics and feasibility of these valves. ... The system is connected and actuated by a pulsatile pump system (Superpump system, VSI, SPS3891, Vivitro systems Inc., Victoria, BC, Canada), which operates based on a VSI Wave Generator VG2001 (Vivitro Systems Inc., Victoria, BC, Canada) and controlled by a ...Dynamics Mechanical Strains of Tricuspid Valve Septal Leaflets
...study to establish a framework for the measurement of the deformation of TV leaflets in a passive ex-vivo beating heart that mimicked the right ventricular dynamic pressure of the normal hearts. ...apexes of fresh porcine hearts (n= 8) were connected to a positive displacement pump (SuperPump AR Series, Vivitro Labs Inc., BC) to generate pulsatile flow in the right side of the hearts. The superior vena cava was connected to a reservoir as the inflow pathway and the pulmonary artery was used for the outflow pathway...On the pulsatile flow through a coronary bifurcation with stent
...study investigates pulsatile flow through models of junctions corresponding to geometries most usually observed in the major coronary artery, with and without stent. ... 31] and [32]. 2.2. Experimental setup. The mean flow has its source in a tank set at constant height, the oscillatory flow is driven by a piston pump (Model SPS 3891,Vivitro Systems, Canada) as shown in Fig. 1. The oscillatory ...Feasibility and Technical Aspects of Proximal Nellix-in-Nellix Extension for Late Caudal Endograft Migration
Purpose: To describe the feasibility and technical aspects of a proximal Nellix-in-Nellix extension to treat caudal stent-graft migration after endovascular aneurysm sealing (EVAS) in the in vitro and in vivo settings. ... Silicone anatomical models were used in conjunction with a pulsatile flow pump (SuperPump; Vivitro Labs Inc, Victoria, British Columbia, Canada). The system was tuned to a pressure of ~120/80 mm Hg, with 4.5- to 5-L/min flow at a rate of 70 beats/min. ...Hybrid textile heart valve prosthesis: preliminary in vitro evaluation
Transcatheter aortic valve implantation (TAVI) is nowadays a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in these devices for over a decade now with over 100,000 implantations... ...The purpose of the present work is to study in vitro the mechanical as well as the hydrodynamic behavior of a hybrid elastic textile valve device combining non-deformable PET yarn and elastic polyurethane (PU) yarn... ... times for each valve. Durability testing of the devices. The prototypes were tested on a commercial fatigue apparatus (Vivitro Labs Inc., Victoria, Canada) equipped with an electromagnetic drive mechanism. Six valve prototypes ...Surface Strains of Porcine Tricuspid Valve Septal Leaflets Measured in Ex-vivo Beating Hearts
...For the first time, the porcine valve leaflets deformation was measured in a passive ex-vivo beating heart without isolating and remounting the valve annuli. In particular, the right ventricular apexes of porcine hearts (n = 8) were connected to a pulse-duplicator pump that maintained a pulsatile flow from and to a reservoir connected to the right atrium and the pulmonary arteries... A positive displacement pump 116 (SuperPump AR Series, Vivitro Labs Inc., BC, Canada) was connected to the apex of the right 117 ventricle after an incision was carefully made at this location (as described in more detail below)...An Experimental and Computational Study on the Effect of Caval Valved Stent Oversizing
Transcatheter tricuspid valves are implanted onto the cavoatrial junction in order to avoid the challenging task of anchoring the valve onto the complex tricuspid valve annulus. ...little is known about optimum extent of oversizing of the valved stent in a vena cava. In this study, we implanted valves of the same diameter onto the larger sized inferior vena cava (IVC) and a smaller sized superior vena cava (SVC). ... that half of the valve protrudes out of the vena cava. This is to comply with the anatomical constraint of not occluding the hepatic vein. The pulsatile flow loop was driven by a wave-generating piston pump (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada). ...In Vitro Pulsatile Performance Evaluation of the HeartMate PHP TM (Percutaneous Heart Pump)
The HeartMate PHP is a 13F catheter-based trans-aortic heart pump with a collapsible distal portion that expands to 24F to provide minimally invasive acute hemodynamic stabilization and left ventricular unloading in both prophylactic and emergent clinical settings... Objective: To evaluate the interaction of the HeartMate PHP with native cardiovascular system via in vitro pulsatile mock flow loop testing. A custom-built pulsatile heart simulator adapted from Vivitro Pulse Duplicator (Vivitro Labs Inc., Canada) was tuned to generate physiological flow pressure waveforms while mimicking the preload sensitivity of the native heart.Development & Design of Improved Commissure for Tissue-Engineered Transcatheter Heart Valves
While most commercial valves today use chemically-fixed porcine tissue in the construction of the replacement valves, the Tranquillo group has been exploring the use of decellularized, engineered tissue as leaflet material... ...The goal of this project was to engineer a commissure design to mitigate valve failure through tissue tearing, and to improve overall valve hemodynamics. (I.e. reduction of PVL)... ...Prototype TEHVs were tested to failure using a ViVitro Labs pulse duplicator, running custom LabView data acquisition software...A biomimetic bi-leaflet mitral prosthesis with enhanced physiological left ventricular swirl restorative capability
Mechanical heart valve prostheses are often implanted in young patients due to their durability and long-term reliability. However, existing designs are known to induce elevated levels of blood damage and blood platelet activation... ...This study proposes a bi-leaflet mechanical heart valve design (Bio-MHV) that mimics the geometry of a human mitral valve, with the aim of reducing turbulence levels in the left ventricle by replicating physiological flow patterns... ... A pulsatile pump (ViVitro Labs Inc., Victoria, BC) attached to the working chamber drove the blood analog around the flow loop, via the pumping action of the silicon left ventricle, as shown in Fig. 1c. Fig. 2 a A mitral flow waveform sample observed in the experiments. ...High-speed visualization of soap bubble blowing and image-processing-based analysis of pinch-off dynamics
Soap bubble blowing has long been an amusement for humans, and the process involves pinch-off similarly to liquid drops and gas bubbles. ... 2.4.2 Measurement using a Pitot tube. To validate the image-based speed measurement, we measured the airflow speed at the center of the nozzle outlet (U e ) using a Pitot static tube (PAA-8-KL, United Sensor Corp.) with pressure transducers (Pulse Duplicator, ViVitro Labs). ...Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves
The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature. ... 2. Material and Methods. In this study, all experiments were carried out using a hydro-mechanical pulse duplicator (Vivitro Superpump System SP3891, ViVitro Labs Inc., Canada), with pressure catheters monitoring the pressure upstream and downstream of the aortic valve. ...Time-Resolved Micro PIV in the Pivoting Area of the Triflo Mechanical Heart Valve
The Lapeyre-Triflo FURTIVA valve aims at combining the favorable hemodynamics of bioprosthetic heart valves with the durability of mechanical heart valves (MHVs). ... physiological con- ditions. It is driven by a peristaltic pump (Superpump, Vivitro Systems, Victoria, BC, Canada) (1) which generates a directed pulsatile flow through the test section (3). The net flow through the transparent test section is ...A D-Shaped Bileaflet Bioprosthesis Which Replicates Physiological Left Ventricular Flow Patterns
... physiological conditions. It is driven by a peristaltic pump (Superpump, Vivitro Systems, Victoria, BC, Canada) (1) which generates a directed pulsatile flow through the test section (3). The net flow through the transparent test section is ...Flow-Induced Damage to Blood Cells in Aortic Valve Stenosis
Valvular hemolysis and thrombosis are common complications associated with stenotic heart valves. This study aims to determine the extent to which hemodynamics induce such traumatic events. The viscous shear stress downstream of a severely calcified bioprosthetic valve was evaluated via in vitro 2D particle image velocimetry measurements. ... Calcification was present on all the leaflets with a very small tear, less than 0.5 mm, on one of the leaflets (Figs. 1a, 1b). The bioprosthesis was tested at room temperature in a custom-built pulse duplicator system (ViVitro Systems, Inc., Victoria, Canada). ...A Novel Method for Optical High Spatiotemporal Strain Analysis for Transcatheter Aortic Valves In Vitro
The aim of this study was to develop a platform for noncontact TAVI valve deformation analysis with both high temporal and spatial resolutions based on stereophotogrammetry and digital image correlation (DIC). A left-heart pulsatile in vitro flow loop system for mounting of TAVI valves was designed. ... Based on a piston pump (ViVitro SuperDup'r pump, ViVitro systems, Victoria, BC, Canada) a left-heart in vitro flow loop with peripheral units comprising a ventricular chamber, an atrial reservoir, an aortic root in which test valves can be installed, an arterial compliance section ...Are the Current Doppler Echocardiography Criteria Able to Discriminate Mitral Bileaflet Mechanical Heart Valve Malfunction? An In Vitro Study
... Jude Medical size 23 mm, a resistance and a compliance). The BMHV to be tested is placed directly between the left atrium and the left ventricle molds. The activation of the left ventricle is performed by a Vivitro superpump (VivitroLabs, Victoria, BC, Canada). ...A Parametric Computational Study of the Impact of Non-circular Configurations on Bioprosthetic Heart Valve Leaflet Deformations and Stresses: Possible Implications for Transcatheter Heart Valves
... The hydrodynamic testing was per- formed using 0.9% saline solution in the commercially available Left Heart Simulator (Vivitro Systems), which simulates function of the heart by generating pulsatile flow through prosthetic heart valves. ...In the EllipMinor and EllipMajor configurations, the maximum principal stress occurred near the center of the free edge of the “stretched” leaflets. These results further affirm recommendations by the International Standards Organization (ISO) that pre-clinical testing should consider non-circular configurations for transcatheter valve durability testing.Effect of oversizing and elliptical shape of aortic annulus on transcatheter valve hemodynamics: An in vitro study
This in-vitro study aims to assess and compare the valve hemodynamic performances of the Edwards SAPIEN transcatheter heart valve (THV) in the different current conditions of use: important oversizing in small circular annuli and in elliptical annuli, moderate oversizing in circular and in elliptical annuli of various degrees of eccentricity.In vitro hemodynamic testing of Amplatzer plugs for paravalvular leak occlusion after transcatheter aortic valve implantation
In this study, a realistic in vitro model of coronary artery flow was developed and used to investigate the impact of TAV deployed orientations on coronary flow. The coronary hemodynamics was first replicated mathematically using a lumped parameter model with time-varying myocardial resistance. ...based on research performed with the ViVitro Pulse Duplicator.Development of an In Vitro Model to Characterize the Effects of Transcatheter Aortic Valve on Coronary Artery Flow
Impairment of coronary artery flow, in either acute or chronic conditions, is a severe complication of transcatheter aortic valve (TAV) implantation, which can arise due to improper TAV positioning. ... LHS. An LHS was designed with the intention of providing physiological flow and pressure waveforms in the left atrium, left ventricle (LV), and ascending aorta, similar to commercially available devices such as the ViVitro LHS (ViVitro Labs, Victoria, Canada) but with additional ...Role of mitral annulus diastolic geometry on intraventricular filling dynamics
...The results support the hypothesis that a D-shaped mitral annulus reduces dissipative energy losses in ventricular filling during diastole, and in turn suggests that a symmetric stent design does not provide lower filling efficiency than an equivalent asymmetric design. ...fluctuations were imposed in a fluid-filled chamber housing the LV physical model using a programmable piston pump (Superpump, Vivitro Systems; British Columbia, Canada). The pressure fluctuations resulted in the deformation of the LV model, driving flow through ...6-Month Aortic Valve Implantation of an Off-the-Shelf Tissue-engineered Valve in Sheep
Diseased aortic valves often require replacement, with over 30% of the current aortic valve surgeries performed in patients who will outlive a bioprosthetic valve. While many promising tissue-engineered valves have been created in the lab using the cell-seeded polymeric scaffold paradigm, none have been successfully tested long-term in the aortic position of pre-clinical model. ... A customized pulse duplicator system was designed based on a commercial wave generator and pump (ViVitro Systems). ...The combined role of sinuses of Valsalva and flow pulsatility improves energy loss of the aortic valve
Normal aortic valve opening and closing movement is a complex mechanism mainly regulated by the blood flow characteristics and the cyclic modifications of the aortic root. Our previous in vitro observations demonstrated that the presence of the Valsalva sinuses, independently from root compliance, is important in reducing systolic pressure drop across the aortic valve. ... The hydrodynamic performances under pulsatile flow regimen were investigated, using a Vivitro System, Inc. ... Direct visualization of valve operating condition was performed, using an ultrafast speed camera (Casio Exlim Ex F1), mounted on top of the Vivitro system [19, 20]. ...Hemodynamic and thrombogenic analysis of a trileaflet polymeric valve using a fluid-structure interaction approach
... The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach. The FSI model replicated experimental conditions of the valve as tested in a ViVitro Left Heart Simulator (ViVitro Labs Inc., Victoria, BC, Canada). ... FSI data, ViVitro data. Cardiac output (L/min), 5.62, 5.50. ...Hemodynamic Performance of Edwards Intuity Valve in a Compliant Aortic Root Model
...It was the aim of this study to perform hemodynamic and kinematic measurements for this type of valves to serve as a baseline for following studies which investigate the effect of the aortic root on the valve performance. To this end, the Edwards Intuity aortic valve was investigated in a new in vitro flow loop mimicking the left heart...Hemodynamics in the Pivoting area of the Triflo Mechanical Heart Valve
...so called hot spots, where activated platelets might aggregate and form a thrombus that can ultimately lead to leaflet blockage. It is the aim of this study to assess the hemodynamics in the pivoting area of the Triflo valve.Effects of Bileaflet Mechanical Mitral Valve Rotational Orientation on Left Ventricular Flow Conditions
We studied left ventricular flow patterns for a range of rotational orientations of a bileaflet mechanical heart valve (MHV) implanted in the mitral position of an elastic model of a beating left ventricle (LV). The valve was rotated through 3 angular positions (0, 45, and 90 degrees) about the LV long axis. ... MHV angular positions. Heart rate and stroke volume were kept constant. MATERIALS AND METHODOLOGY We utilized a mechanical left heart model (ViVitro Labs, Inc., Victoria, Canada) (Fig. 1A). The model was comprised ...Classification of Unsteady Flow Patterns in a Rotodynamic Blood Pump: Introduction of Non-Dimensional Regime Map
Rotodynamic blood pumps (also known as rotary or continuous flow blood pumps) are commonly evaluated in vitro under steady flow conditions. However, when these devices are used clinically as ventricular assist devices (VADs), the flow is pulsatile due to the contribution of the native heart. ... Flow Loop The pump prototype was dynamically tested using a cardiovascular simulator circuit (modified from Vivitro Systems Inc., Victoria, British Columbia) built around a silicone mock left ventricle (LV) encased in a rigid acrylic chamber ...Non-invasive vascular elastography with plane strain incompressibility assumption using ultrafast coherent compound plane wave imaging
Recent developments in compound plane wave (CPW) imaging have led to high speed and high resolution imaging. In this study, we present the performance of NIVE using CPW. We show the impact of CPW beamforming on strain estimates compared to conventional focus sequences.Cardiovascular magnetic resonance compatible physical model of the left ventricle for multi-modality characterization of wall motion and hemodynamics
... A programmable piston pump (PPP; Vivitro Systems Inc., Victoria, Canada) was used to induce the LV wall motion by altering the pressure of the fluid in the space between the interior of acrylic chamber housing the LV model and the exterior of the LV model. ...Evaluating the performance of prosthetic heart valves: transvalvular pressure drop vs. vortex ring formation number
A prominent performance metric used by the FDA to evaluate prosthetic heart valves is transvalvular pressure drop. ... METHODS To investigate vortex ring formation as a function of time relative to changing operating conditions, a piston driven heart simulator (Vivitro Heart system SD2001-1) was used. ... (3) The data collected from the Vivitro Heart system was used to find . ...Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes
Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. ... Transducers (ViVitro Systems) were placed downstream, upstream, and on the ablumenal surface of the test valve to record system pressures. Instantaneous flow rates were measured using an electromagnetic flow meter (Carolina ...Generation of Simulated Calcific Lesions in Valve Leaflets for Flow Studies
The study aim was to develop a laboratory protocol for the fabrication of tissue valve models mimicking mild and moderate calcific stenosis, for future use in flow studies. ... near-physiologic hemodynamics. The flow loop was driven by a programmable piston pump (Vivitro), and included resistance and compliance units to mimic the characteristics of the systemic vascular tree (Fig. 3A). The system ...In Vitro Investigation of the Hemodynamics of Transcatheter Heterotopic Valves Implantation in the Cavo‐Atrial Junction
Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. ... by 19% as an initial study. The silicone atrium was incorporated into a pulsatile flow loop that was driven by a wave-generating piston pump (SuperPump AR series, ViVitro Labs Inc., Victoria, BC, Canada). The flow rate in the ...Strain examinations of the left ventricle phantom by ultrasound and multislices computed tomography imaging
The main aim of this study was to verify the suitability of the hydrogel sonographic model of the left ventricle (LV) in the computed tomography (CT) environment and echocardiography and compare the radial strain calculations obtained by two different techniques: the speckle tracking ultrasonography and the multislices computed tomography (MSCT). ... equal to 0.28 dB/cm (at 2.95 MHz). Our model of the LV was driven by a computer-controlled hydraulic piston Super-Pump (Vivitro Inc., Canada) with adjustable fluid volumes and various loads. During a cycle of the pump, the ...Effect of aortic annulus size and prosthesis oversizing on the hemodynamics and leaflet bending stress of transcatheter valves: an in vitro study
There is few data about the patient- and prosthesis- related factors influencing the hemodynamics of transcatheter heart valves (THVs). The objective of this in vitro study was to assess the effect of aortic annulus size and prosthesis oversizing on the valve hemodynamics and estimated leaflet bending stress of the SAPIEN balloon-expandable THV. ... THV). Methods. In Vitro Model. For the purpose of this study, a left heart duplicator system was used (ViVitro Labs. Inc, BC, Canada). This simulator is capable of reproducing physiological pressure and flow waveforms. Briefly ...The influence of the aortic root geometry on flow characteristics of a prosthetic heart valve
...he objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement.... ...By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots....Normal physiological conditions maintain the biological characteristics of porcine aortic heart valves: an ex vivo organ culture study.
The aortic valve functions in a complex mechanical environment which leads to force-dependent cellular and tissue responses. Characterization of these responses provides a fundamental understanding of valve pathogenesis. The aim of this work was to study the biological characteristics of native porcine aortic valves cultured in an ex vivo pulsatile organ culture system capable of maintaining physiological pressures (120/80 mmHg) and cardiac output (4.2 l/min).Design of a novel polymeric heart valve
Polymeric heart valves could offer an optimum alternative to current prostheses, by joining the advantages of mechanical and bioprosthetic valves. Though a number of materials suitable for this application have recently become available, significant improvements in the valve design are still needed. In this paper, a novel polymeric heart valve design is proposed and its optimization procedure, based on the use of finite elements, is described...Simultaneous measurements of velocity and deformation in flows through compliant diaphragms
Flow through a circular orifice in a deformable diaphragm mounted in a pipe was studied experimentally as a simple yet suitable case for validating numerical fluid/structure interaction (FSI) codes including structures with significant deformation and strain. The flow was characterized using pressure taps, particle image velocimetry (PIV), and hot-film anemometry while deformation of the compliant diaphragm was determined directly from PIV images.Comparison of Three Dimensional Proximal Isovelocity Surface Area to Cardiac Magnetic Resonance Imaging for Quantifying Mitral Regurgitation
The aim of our study was, to evaluate 3-D color Doppler proximal isovelocity surface area (PISA) as a tool for quantitative assessment of mitral regurgitation (MR) against in vitro and in vivo reference methods. A customized 3-D PISA software was validated in vitro against a flowmeter MR phantom. Sixty consecutive patients, with ≥mild MR of any etiology, were recruited and the regurgitant volume (RVol) was measured by 2-D PISA, 3-D peak PISA, 3-D integrated PISA, using transthoracic (TTE) and transesophageal echocardiography (TEE).A fluid-structure approach to optimize the thrombogenic potential of artificial heart valves
Experimental procedures are commonly used to obtain an overall quantification of the fluid dynamic and thrombogenic performances of cardiovascular devices [1]... (B) ViVitro gold standard testing benchmark (ViVitro Labs, BC, Canada) Boundary conditions ... obtaining comparable working conditions between the computational model and the ViVitro benchmark. Figure 2 – Schematic visualization of the ideal ...Finding the ideal biomaterial for aortic valve repair with ex vivo porcine left heart simulator and finite element modeling
ABSTRACT Aortic valve (AV) repair (AVr) has become an attractive alternative to AV replacement for the correction of aortic insufficiency; however, little clinical evidence exists in determining which biomaterial at AVr would be optimal. Cusp replacement in AVr has... All aortic roots were connected to the ViVitro Left Heart Simulator (LHS; ViVitro Systems, Inc, Victoria, British Columbia, Canada) for baseline valve measurements acting as paired controls...Assessment of radial strain in ultrasonographic model of left ventricle using speckle tracking ultrasound technique and multislice computed tomography.
... Model of the LV was made from solution of POLY(VINYL ALCOHOL). Pulsatile filling of the LV phantom was driven by automatic and computer controlled hydraulic piston pump (Vivitro Inc., Canada) with stroke volume of 20 ml and the frequency of 60 impactions per minute. ...Three-dimensional reconstruction of cardiac flows based on multi-planar velocity fields
... We used a heart-flow simulator consisting of a hydraulic pump system (Superpump system, VSI, SPS3891, Vivitro systems Inc., Victoria, BC, Canada) that operates based on a VSI Wave Generator VG2001 (Vivitro Systems Incorporated, Victoria, BC, Canada), as previously ...Evaluation of Left Ventricle Phantom by Ultrasound and Multislices Computer Tomography Imaging
... Our model of the LV was driven by the computer-controlled hydraulic piston Super-Pump (Vivitro Inc., Canada) with adjustable fluid volumes. ... The data were reconstructed every 10% of the R-to-R interval of the ECG signal produced by the Vivitro SuperPump control device. ...Transcatheter aortic valves inadequately relieve stenosis in small degenerated bioprostheses.
Transcatheter aortic valves (TAVs) are a promising treatment for high risk surgical patients suffering from degeneration of previously implanted bioprostheses (valve-in-valve therapy).Role of sinus wall compliance in aortic leaflet function
Functional morphology of the normal aortic root was studied in vitro using 500 frames/s cinematography. Stiffening of the aortic wall by spraying its exterior with plastic adhesive led to compromised function of the leaflets...Effective ventricular unloading by left ventricular assist device varies with stage of heart failure: cardiac simulator study.
Although the use of left ventricular assist devices (LVADs) as a bridge-to-recovery (BTR) has shown promise, clinical success has been limited due to the lack of understanding the timing of implantation, acute/chronic device setting, and explantation. This study investigated the effective ventricular unloading at different heart conditions by using a mock circulatory system (MCS) to provide a tool for pump parameter adjustments.The congenitally bicuspid aortic valve: how does it function? Why does it fail?
The study was intended to investigate the reason why congenitally bicuspid valves (CBAVs), which may function hemodynamically and clinically well, have a high early failure rate.Quantification of mitral regurgitation with MR phase-velocity mapping using a control volume method
Reliable diagnosis and quantification of mitral regurgitation are important for patient management and for optimizing the time for surgery. Previous methods have often provided suboptimal results. The aim of this in vitro study was to evaluate MR phase-velocity mapping in quantifying the mitral regurgitant volume (MRV) using a control volume (CV) method.Pulsatile flow studies of a porcine bioprosthetic aortic valve in vitro: PIV measurements and shear-induced blood damage
A two-dimensional particle image tracking velocimetry (PIV) system has been used to map the velocity vector fields and Reynolds stresses in the immediate downstream vicinity of a porcine bioprosthetic heart valve at the aortic root region in vitro under pulsatile flow conditions. Measurements were performed at five different time steps...Progress on the development of the MediWatch ambulatory blood pressure monitor and related devices:
The MediWatch is a wrist-mounted noninvasive blood pressure monitor designed to capture the radial pulse waveform using arterial tonometry and yield blood pressure measurements when the waveform is calibrated. An early prototype of this monitor uses a pulse-sensing system with a cylindrical plunger to applanate the radial artery. This prototype was evaluated against simulated blood pressure generated by a pneumatic pressure-pulse generator.Numerical simulation of the dynamics of a bileaflet prosthetic heart valve using a fluid–structure interaction approach:
The main purpose of this study is to reproduce in silico the dynamics of a bileaflet mechanical heart valve (MHV; St Jude Hemodynamic Plus, 27mm characteristic size) by means of a fully implicit fluid-structure interaction (FSI) method, and experimentally validate the results using an ultrafast cinematographic technique.Modified gorlin equation for the diagnosis of mixed aortic valve pathology
The accuracy of the Gorlin equation when applied to mixed valve pathology has not been investigated. An in-vitro study was performed to determine how a range of valve regurgitations and stenoses affects the Gorlin aortic valve area...Mitral mechanical heart valves: in vitro studies of their closure, vortex and microbubble formation with possible medical implications
The goal of the present work was to create the closest possible in vitro fluid dynamic environment in which prosthetic mitral valves in the patients' hearts function, in order to demonstrate whether microbubbles are generated, and if yes, under what conditions and at which stage of the cardiac cycle...Measurement of volumetric flow with no angle correction using multiplanar pulsed Doppler ultrasound
In this paper we show that by scanning at points on the surface of a sphere that the normal angle correction used in pulsed Doppler flow measurements is no longer necessary.Lumped Parameter Model for Computing the Minimum Pressure During Mechanical Heart Valve Closure:
The cavitation inception threshold of mechanical heart valves has been shown to be highly variable. This is in part due to the random distribution of the initial and final conditions that characterize leaflet closure.Geometric modeling of functional trileaflet aortic valves: Development and clinical applications
The dimensions of the aortic valve components condition its ability to prevent blood from flowing back into the heart. While the theoretical parameters for best trileaflet valve performance have already been established, an effective approach to describe other less optimal, but functional models has been lacking...Fluid dynamics of the CarboMedics Kinetic bileaflet prosthetic heart valve
To compare hydrodynamic characteristics of a new bileaflet heart valve, the CarboMedics kinetic cardiac valve prosthesis, with those of a St. Jude Medical (SJM) heart valve...Fluid Dynamic Characteristics of the VentrAssist Rotary Blood Pump
The VentrAssist pump has no shaft or seal, and the device is unique in design because the rotor is suspended passively by hydrodynamic forces, and urging is accomplished by an integrated direct current motor rotor that also acts as the pump impeller. This device has led to many challenges in its fluidic design...Flow instabilities induced by coronary artery stents: Assessment with an in vitro pulse duplicator
An in vitro pulse duplicator system was used to investigate whether coronary artery stents induce downstream flow instabilities. Hot film or electrochemical probes were used to measure wall shear stress before and after deployment of both single and multiple (overlapping) stents in normal and diseased coronary geometries...Experimental Stent-Graft Treatment of Ascending Aortic Dissection
BACKGROUND: This study assessed the feasibility of stent graft treatment of ascending aortic dissections in a porcine in vitro model. METHODS: The entire thoracic aortic aorta including the supraaortic branches was harvested from 12 adult pigs and an intimal tear was artificially created. ...Evidence of nonlinear response of hydrocephalus shunt valves to pulsating flow:
Epicardial Suction: A New Approach to Mechanical Testing of the Passive Ventricular Wall
Doppler Echocardiographic Assessment of Valvular Regurgitation Severity by Measurement of the Vena Contracta: An In Vitro Validation Study
Does Post-Stenotic Dilatation Enhance Collateral Flow?
Discriminant Analysis Of Acoustic Emissions From Bjork-Shiley Heart Valves With And Without Broken Minor Struts
Design of a Sterile Organ Culture System for the Ex Vivo Study of Aortic Heart Valves:
Blood Flow in Distal End-to-side Anastomoses with PTFE and a Venous Patch: Results of an In vitro Flow Visualisation Study
Arteriovenous fistulas aggravate the hemodynamic effect of vein bypass stenoses: An in vitro study
Angiographic Quantification of Contrast Medium Washout from Cerebral Aneurysms after Stent Placement
Acute and Chronic Swine Rete Arteriovenous Malformation Models: Hemodynamics and Vascular Remodeling
Liquid embolic agents are increasingly gaining importance in the embolization of cerebral arteriovenous malformations (AVMs). Currently, the most commonly used agent is N-butyl 2-cyanoacrylate (NBCA). Various NBCA mixtures, arterial hypotension, and Valsalva maneuver (increased positive end-expiratory pressure) during the injection of the acrylate have been used to address hemodynamic and architectural variations of an AVM; however, the precise in vivo polymerization, distribution, and kinetics of NBCA mixtures are unknown. We investigated the effect of different acrylate/Lipiodol mixtures and the addition of glacial acetic acid (GAA) on the penetration, dispersion, and injection force of NBCA.Unsteady entrance flow in a 90° curved tube
Discrimination in vitro between the acoustic emissions from Bjork-Shiley convexo-concave valves with and without a broken minor strut
In Vitro Strain Measurement of a Mechanical Heart Valve in a Pulse Simulator
To ascertain the stress magnitude at the stress concentration areas, in vitro strain measurements on a St. Vincent's mechanical heart valve were carried out in a pulse simulator.A Database Obtained From In Vitro Function Testing of Mechanical Heart Valves:
The effects of dynamic cardiac compression on ventricular mechanics and energetics: Role of ventricular size and contractility
The purpose of this study was to determine the role of ventricular size or contractility in the effectiveness of dynamic cardiac compression in terms of the pressure-volume relationship and myocardial oxygen consumption. In 10 isolated cross-circulated dog hearts, the ventricle was directly compressed during systole.Pressure trap created by vein valve closure and its role in graft stenosis:
Saphenous vein graft stenosis has become the leading cause of reoperation in coronary bypass operations. We investigated the role of vein valves in vein graft stenosis by studying 14 human saphenous veins placed in a simulator of the left side of the heart in parallel with the arterial system.Hydrodynamic function of tilting disc prostheses and bileaflet valves in double valve replacement:
To determine the energy loss attributable to prosthetic valve size and design in double valve replacement, energy consumption of mitral valves (size #25 to #29), of two different designs (Bjork Shiley tilting disc and Carbomedics bileaflet valves), in combination with a small (#21) and large sized (#27) aortic prosthesis, were analyzed in a flow simulator.Experimental analysis of fluid mechanical energy losses in aortic valve stenosis
Current methods for assessing the severity of aortic stenosis depend primarily on measures of maximum systolic pressure drop at the aortic valve orifice and related calculations such as valve area. It is becoming increasingly obvious, however, that the impact of the obstruction on the left ventricle is equally important in assessing its severity and could potentially be influenced by geometric factors of the valve, causing variable degrees of downstream pressure recovery...The importance of slice location on the accuracy of aortic regurgitation measurements with magnetic resonance phase velocity mapping
Although several methods have been used clinically to evaluate the severity of aortic regurgitation, there is no purely quantitative approach for aortic regurgitant volume (ARV) measurements. Magnetic resonance phase velocity mapping can be used to quantify the ARV, with a single imaging slice in the ascending aorta, from through-slice velocity measurements.DYNAMIC CARDIAC COMPRESSION IMPROVES CONTRACTILE EFFICIENCY OF THE HEART
Correlation of radionuclide and optical tracer assessments of fluid flow in artificial ventricles
Anterior and posterior left ventricular sarcomere lengths behave similarly during ejection:
Fluid dynamics of the CarboMedics kinetic bileaflet prosthetic heart valve
Assessment of Small-Diameter Aortic Mechanical Prostheses
Accuracy of Arterial Pulse-Wave Velocity Measurement Using MR
Prosthetic heart valve evaluation by magnetic resonance imaging
To evaluate the potential of magnetic resonance imaging (MRI) for evaluation of velocity fields downstream of prosthetic aortic valves. Furthermore, to provide comparative data from bileaflet aortic valve prostheses in vitro and in patients.Independent effects of preload, afterload, and contractility on left ventricular torsion
Shortening of oblique left ventricular (LV) fibers results in torsion. A unique relationship between volume and torsion is therefore expected, and the effects of load and contractility on torsion should be predictable. However, volume-independent behavior of torsion has been observed, and the effects of load on this deformation remain controversial....Analysis of regurgitation, mean systolic pressure drop and energy losses for two artificial aortic valves
A Physical Model Describing the Mechanism for Formation of Gas Microbubbles in Patients with Mitral Mechanical Heart Valves
This study was aimed at developing a physical model, supported by experimental observations, to describe the formation and growth of microbubbles seen in patients with mitral mechanical heart valves (MHV). This phenomenon, often referred to as high intensity transient signals (HITS), appears as bright, intense, high-velocity and persistent echoes detected by Doppler ultrasonography at the instant of closure.Transpecies heart valve transplant: advanced studies of a bioengineered xeno-autograft
Tissue engineering approaches utilizing biomechanically suitable cell-conductive matrixes should extend xenograft heart valve performance, durability, and growth potential to an extent presently attained only by the pulmonary autograft. To test this hypothesis, we developed an acellular, unfixed porcine aortic valve-based construct. The performance of this valve has been evaluated in vitro under simulated aortic conditions, as a pulmonary valve replacement in sheep, and in aortic and pulmonary valve replacement in humans.Motion correction for the quantification of mitral regurgitation using the control volume method
Quantifying mitral regurgitation is difficult because of the complexity of the flow, geometry and motion of the mitral valve. In this paper a MRI compatible phantom was built incorporating a left ventricle and mitral valve motion. Valve motion was obtained using a pneumatic piston. The mitral valve was made regurgitant and the regurgitant volume quantified using a modified control volume method. The modification to the method was the addition of mitral motion correction...Influence of sizing and subcoronary implantation technique on the function of porcine aortic homografts
The function and longevity of the homograft aortic valve may be influenced by valve size and subcoronary implantation technique. Dynamic function and leaflet configuration of the porcine aortic valve were analysed first in its natural root in a left heart simulator using glycerol at 120/80 mm Hg pressure and 4 l min-1 Cardiac Output (C.O.)...In vitro comparison of steady and pulsatile flow characteristics of jellyfish heart valve
In examining the hydrodynamic performance of artificial heart valves in vitro, experiments are carried out under either steady or pulsatile flow conditions. Steady flow experiments are simple to set up and analysis of the data is also simple; however, their validity and accuracy have been questioned...Pressure-Volume Relationship of a Pulsatile Blood Pump for Ventricular Assist Device Development
A mathematical model describing the pressure-volume relationship of the Novacor left ventricular assist system (LVAS) was developed. The model consists of lumped resistance, capacitance, and inductance elements with one time varying capacitor to estimate the cyclic pressure generation of the pump using pump volume measurement.Method of ranking of heart valve characteristics at mitral position based on statistical model analysis
The purpose of this study was to explore a valve selection criterion based on the impact force generated at valve closure, and to test a statistical mathematical model for comparing valve performance. The impact force generated at valve closure in the mitral position was measured continuously, using a load cell mounted in the left atrial section of a mock circulatory system...Flow Characteristics Past Jellyfish and St. Vincent Valves in the Aortic Position Under Physiological Pulsatile Flow Conditions:
Thrombus formation and hemolysis have been linked to the dynamic flow characteristics of heart valve prostheses. To enhance our understanding of the flow characteristics past the aortic position of a Jellyfish (JF) valve in the left ventricle, in vitro laser Doppler anemometry (LDA) measurements were carried out under physiological pulsatile flow conditions...Evaluation of the Precision of Magnetic Resonance Phase Velocity Mapping for Blood Flow Measurements
Decellularized human valve allografts
A new aortic root prosthesis with compliant sinuses for valve-sparing operations
Ultrafast Flow Quantification With Segmented k-Space Magnetic Resonance Phase Velocity Mapping
Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3-5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes).Prosthetic replacement of the aorta is a risk factor for aortic root aneurysm development
Aortic root replacement for prosthetic aortic valve endocarditis with accompanying destruction of the aortic root is a well-established surgical intervention. However, there is still no consensus whether prosthetic material or allogeneic material should be used. Here we report on our experience with prosthetic composite and aortic allograft root replacement in such patients during a 10-year interval.Particle Image Velocimetry Assessment of Stent Design Influence on Intra-Aneurysmal Flow
Hydrodynamic function of the second-generation mitroflow pericardial bioprosthesis
Accurate quantification of steady and pulsatile flow with segmented k-space magnetic resonance velocimetry
Correlation Between Negative Near-Wall Shear Stress in Human Aorta and Various Stages of Congestive Heart Failure
Value and limitations of aortic valve resistance with particular consideration of low flow–low gradient aortic stenosis: an in vitro study
The calculation of valve resistance (R) rather than aortic valve area (AVA) has been proposed for the assessment of aortic stenosis (AS), based on the claim that it is less flow-dependent. Even more importantly, valve resistance has been reported to distinguish between truly severe and "pseudosevere" AS in patients with low cardiac output. However, the diagnostic value of valve resistance remains controversial.Fast Measurements of Flow through Mitral Regurgitant Orifices with Magnetic Resonance Phase Velocity Mapping
Magnetic-resonance (MR) phase velocity mapping (PVM) shows promise in measuring the mitral regurgitant volume. However, in its conventional nonsegmented form, MR-PVM is slow and impractical for clinical use. The aim of this study was to evaluate the accuracy of rapid, segmented k-space MR-PVM in quantifying the mitral regurgitant flow through a control volume (CV) method.Design and construction of a left ventricular cardiovascular assist device:
What parameters affect left ventricular diastolic flow propagation velocity? in vitro studies using color m-mode doppler echocardiography
Insufficient data describe the relationship of hemodynamic parameters to left ventricular (LV) diastolic flow propagation velocity (Vp) measured using color M-mode Doppler echocardiography.Three-Dimensional Numeric Simulation of Flow Through an Aortic Bileaflet Valve in a Realistic Model of Aortic Root
A three-dimensional, realistic model of an aortic mechanical heart valve and Valsalva sinuses was developed to predict, by means of a numerical time dependent simulation, the flow field during a fraction of the systolic period. The numeric simulation was performed upon a model of valve similar to a Carbomedics 27 mm placed in a physiologic aortic root shaped model,...Slice location dependence of aortic regurgitation measurements with MR phase velocity mapping
Although several methods have been used clinically to assess aortic regurgitation (AR), there is no "gold standard" for regurgitant volume measurement. Magnetic resonance phase velocity mapping (PVM) can be used for noninvasive blood flow measurements.Motion correction for the quantification of mitral regurgitation using the control volume method
Quantifying mitral regurgitation is difficult because of the complexity of the flow, geometry and motion of the mitral valve. In this paper a MRI compatible phantom was built incorporating a left ventricle and mitral valve motion. Valve motion was obtained using a pneumatic piston. The mitral valve was made regurgitant and the regurgitant volume quantified using a modified control volume method. The modification to the method was the addition of mitral motion correction. TFirst Human Case of Retrograde Transcatheter Implantation of an Aortic Valve Prosthesis
The transcatheter route is an emerging approach to treating valvular disease in high-risk patients. The 1st clinical antegrade transcatheter placement of an aortic valve prosthesis was reported in 2002. We describe the first retrograde transcatheter implantation of a new aortic valve prosthesis, in a 62-year-old man with inoperable calcific aortic stenosis and multiple severe comorbidities.Comparison of the flow downstream two prototypes of a new monoleaflet artificial aortic heart valve by means of PIV visualization
Quantitative approach to aortic valve-sparing surgery
Our goal was to understand why it is difficult to achieve reliable valve competence after aortic valve-sparing surgery, and to propose quantitative data aimed at improving the outcome of the procedure. Valve-sparing procedures were performed in patients with dilated aortic roots and aortic regurgitation, and reproduced in physical models to explore what should be the restored dimensions of the aortic root and leaflets for valve sparing to be successful.In Vitro 3D High Speed Piv Measurements Behind An Aortic Artificial Heart Valve
Worldwide are performed approximately 225,000 heart valve operation procedures. Various heart valve types have different efficiency, beside others, mostly given by the quality of the flow in all regions across the valve. For the visualization of the flow we employed Stereo High Speed Particle Image Velocimetry (SHSPIV)...Faster flow quantification using sensitivity encoding for velocity-encoded cine magnetic resonance imaging: In vitro and in vivo validation
To test the agreement between conventional and sensitivity-encoded (SENSE) velocity encoded cine (VEC) MRI in a flow phantom and in subjects with congenital and acquired heart disease...Development of Squeeze Flow in Mechanical Heart Valve: A Particle Image Velocimetry Investigation
Cavitation Behavior of Three Monoleaflet Valves Under Accelerated Testing
Anticoagulation for An Artificial Liver Support Device, the I.M.P.A.C.T. System(Tm) (Intermittent Modular Plasma Adsorption of Cytokines and Toxins)
An In Vitro Study of Changing Profile Heights in Mitral Bioprostheses and Their Influence on Flow
Shear Stress Investigation Across Mechanical Heart Valve
The particle image velocimetry technique was used to study the shear field across a transparent mechanical heart valve model in one cardiac cycle. Shear stress was continuously increased until peak systole and high turbulent stress was observed at the orifice of the central channel and also around the occluder trailing tips.Influence of Ventricular Pressure Drop on Mitral Annulus Dynamics Through the Process of Vortex Ring Formation:
Several studies have suggested that the mitral annulus displacement and velocity in early diastole can be used as indicators of diastolic performance.Flow Visualization Through Two Types of Aortic Prosthetic Heart Valves Using Stereoscopic High-speed Particle Image Velocimetry
The number of candidates waiting for a heart valve replacement rises yearly. Even though there is a trend toward implantation of biological valves or reconstruction, the prosthetic heart valves (PHVs) are still commonly used for implantation or as a part of cardiac assist devices in many countries worldwide...Correlation Between Vortex Ring Formation and Mitral Annulus Dynamics During Ventricular Rapid Filling
Stentless Valves Treated by the L-Hydro Process in the Aortic Position in Sheep:
Calcification of glutaraldehyde-treated bioprosthetic heart valves is a major cause of long-term failure. We studied porcine aortic valves treated by the L-Hydro process and implanted into 14 juvenile sheep (group 1). Another 10 sheep were implanted with glutaraldehyde-treated porcine bioprostheses (group 2).Systemic pressure does not directly affect pressure gradient and valve area estimates in aortic stenosis in vitro
Hypertension is a frequent finding in patients with aortic stenosis (AS). However, controversial data about the influence of systemic blood pressure on the quantification of AS have been published.Effect of oscillation on elevating shear stresses
A Novel, Low Cost, Disposable, Pediatric Pulsatile Rotary Ventricular Pump For Cardiac Surgery that Provides a Physiological Flow Pattern
Hydrodynamic Evaluation of a Minimally Invasive Heart Valve in an Isolated Aortic Root Using a Modified In Vitro Model
Implantation methods for commercially available heart valve prostheses require open-chest access to the heart to perform the suturing process. In order to alleviate this complicated surgical implant technique, a “stent-valve” design was developed that will provide a less cumbersome implantation method and therefore a less invasive access to the heart...On Mitral Valve Dynamics and its Connection to Early Diastolic Flow
In the field of cardiology, the current ability to accurately detect diastolic dysfunction is unsatisfactory due to the lack of an effective diagnostic index. Isolated indexes obtained from echocardiography are all restricted to a certain aspect of ventricular diastolic function only, and individually cannot be regarded...Energy Loss Due to Paravalvular Leak With Transcatheter Aortic Valve Implantation
A method for the measurement of left ventricular overload for aortic valve insufficiency
Development and evaluation of a novel artificial catheter-deliverable prosthetic heart valve and method for in vitro testing
Revisiting the Simplified Bernoulli Equation
The assessment of the severity of aortic valve stenosis is done by either invasive catheterization or non-invasive Doppler Echocardiography in conjunction with the simplified Bernoulli equation. The catheter measurement is generally considered more accurate, but the procedure is also more likely to have dangerous complications.Flow analysis in patient specific lower airways using PIV
ABSTRACT The objective of this study is to analyze the flow pattern trough a patient specific lower airway under multiple breathing conditions. The measured Particle Image Velocimetry (PIV) results are quantitatively and quantitatively compared ...Structural analysis of the natural aortic valve in dynamics: From unpressurized to physiologically loaded
A novel finite element model of the natural aortic valve was developed implementing anisotropic hyperelastic material properties for the leaflets and aortic tissues, and starting from the unpressurized geometry. Static pressurization of the aortic root, silicone rubber moulds and published data helped to establish the model parameters, while high-speed video recording of the leaflet motion in a left-heart simulator allowed for comparisons with simulations.Ex vivo hemodynamic assessment of mechanical aortic valve gradients using a high-fidelity pressure wire
Abstract OBJECTIVES: Accurate assessment of prosthetic mechanical valve malfunction is challenging for non-invasive and invasive techniques. We evaluated a 0.014-inch pressure-sensing coronary guidewire to assess mechanical valve dysfunction.Evaluation of an asymmetric stent patch design for a patient specific intracranial aneurysm using Computational Fluid Dynamic (CFD) calculations in the Computed Tomography (CT) derived lumen
Stenting may provide a new, less invasive therapeutic option for cerebral aneurysms. However, a conventional porous stent may be insufficient in modifying the blood flow for clinical aneurysms. We designed an asymmetric stent consisting of a low porosity patch welded onto a porous stent for an anterior cerebral artery aneurysm of a specific patient geometry to block the strong inflow jet... … 2.5. Angiographic flow visualization The rapid prototype aneurysm model was inserted in a flow loop consisting of a waveform generator, a pump, and a flow meter; the flow was activated by a heart simulating pump (Vivitro Systems Inc., Canada) …Application of speckle tracking echocardiography in the assessment of left ventricular function. In vivo and in vitro studies
DURABLE MULTI-LAYER HIGH STRENGTH POLYMER COMPOSITE SUITABLE FOR IMPLANT AND ARTICLES PRODUCED THEREFROM
Product Development Cycle of a Surgical Device for Mitral Valve Repair and Surgical Training Simulator Development Plan for the Same
The objective of this thesis is to 1) describe the product development cycle for the DS1000, a surgical instrument for Mitral Valve repair. A chapter is then provided for 2) adapting the device development cycle to a development cycle for a simulator. This is followed by 3)...Analysis of the flow field downstream a bileaflet valve inside an aortic arch laboratory model
Optimization and Verification of a Novel Trileaflet Polymeric Prosthetic Heart Valve
Valvular heart disease remains a significant public health issue with Calcific Aortic Valve Disease (CAVD) its most life threatening form. Current treatment for CAVD involves open-heart surgical replacement of the diseased aortic valve (AV) with either a tissue (THV) or mechanical (MHV) prosthesis, with THVs being mostly nonthrombogenic but vulnerable to structural valve deterioration (SVD) and MHVs being highly durable but thrombogenic, thus requiring lifelong anticoagulant therapy.Experimental technique of measuring dynamic fluid shear stress on the aortic surface of the aortic valve leaflet
ABSTRACT Aortic valve (AV) calcification is a highly prevalent disease with serious impact on mortality and morbidity. The exact cause and mechanism of the progression of AV calcification is unknown, although mechanical forces have been known to play...DURABLE HIGH STRENGTH POLYMER COMPOSITE SUITABLE FOR IMPLANT AND ARTICLES PRODUCED THEREFROM
Signal processing of heart signals for the quantification of non-deterministic events
Heart signals represent an important way to evaluate cardiovascular function and often what is desired is to quantify the level of some signal of interest against the louder backdrop of the beating of the heart itself. An example of this type of application is the quantification of cavitation in mechanical heart valve patients.A flowmeter for unsteady liquid flow measurements in total liquid ventilation
Rotary blood pump control using integrated inlet pressure sensor
Due to improved reliability and reduced risk of thromboembolic events, continuous flow left ventricular assist devices are being used more commonly as a long term treatment for end-stage heart failure. As more and more patients with these devices are leaving the hospital, a reliable control system is needed that can adjust pump support in response to changes in physiologic demand.Design conception and experimental setup for in vitro evaluation of mitral prosthetic valves
Valve-in-valve hemodynamics of 20-mm transcatheter aortic valves in small bioprostheses
Transcatheter aortic valve (TAV) implantation is a treatment for selected patients with failing bioprostheses. We previously showed that currently available SAPIEN (Edwards Lifesciences, Irvine, CA) TAV sizes did not yield acceptable valve-in-valve (VIV) hemodynamics in small degenerated bioprostheses because optimal TAV function requires full stent expansion to its nominal size.Dilatation of the ascending aorta in patients with congenitally bicuspid aortic valves
Importance of Shear in Prosthetic Valve Closure Dynamics
The results of recent hematological studies have suggested that, under non-physiological flow conditions, circulating procoagulant proteins activate the coagulation cascade. In the present study, in-vitro estimates of flow transients at or near the time of valve closure, including regional backflow velocity (RBV, m/s), flow acceleration (m/s2), and rate of acceleration (jerk, m/s3), have shed new light on the blood-damage potential of prosthetic valves.Phase-resolved velocity measurements in the Valsalva sinus downstream of a Transcatheter Aortic Valve.
Two sets of phase resolved PIV measurements were performed in the Valsalva sinuses of a glass mock aortic root including three polymeric valve leaflets, before and after the implant of a Medtronic CoreValve TAVI device. The experiments were carried out in a hydro-mechanical cardiovascular pulse duplicator system (Vivitro Superpump System SP3891) r...TCT-81 Ex-Vivo Simulator for Training, Teaching, and Testing of Transcatheter Valve Therapies Based on the Principle of a Passive Beating Heart
Commercially available in-vitro cardiac simulators offer testing opportunities for transcatheter valve therapies (TVT) as they are able to replicate the physiological flow and pressure accurately.High-speed particle image velocimetry to assess cardiac fluid dynamics in vitro: From performance to validation
Abnormality in cardiac fluid dynamics is highly correlated with several heart conditions. This is particularly true in valvular heart diseases and congenital heart defects where changes in flow-field accompany significant variations in chambers’ pressure gradients. Particle Image Velocimetry (PIV) is a convenient technique in assessing cardiac fluid dynamics in vitro...Manufacturing and hydrodynamic assessment of a novel aortic valve made of a new nanocomposite polymer
Synthetic leaflet heart valves have been widely studied as possible alternatives to the current mechanical and bioprosthetic valves. Assessing the in vitro hydrodynamic function of these prostheses is of great importance to predict their hemodynamic behaviour prior to implantation. This study introduces an innovative concept of a low-profile semi-stented surgical aortic valve (SSAV) made of a novel nanocomposite polyurethane with a polycarbonate soft segment (PCU) and polyhedral oligomeric silsesquioxane (POSS) nanoparticles covalently bonded as a pendant cage to the hard segment.Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves.
Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process.A Direct In Vitro Comparison of the Edwards SAPIEN and Medtronic CoreValve Transcatheter Aortic Valve implantation (TAVI) Devices and a Surgical Counterpart
A methodology of measuring coronary flow in a porcine aortic root using a pulsatile flow loop
Experimental and Computational Studies of the Aortic Bi-leaflet Mechanical Heart Valve (BMHV) Hemodynamics in an Idealized Left Ventricle
We aim to validate the performance of our fluid structure interaction (FSI) simulations of a bi-leaflet mechanical heart valve in the aortic position., whose motion is driven by the beating left ventricle. We compare in vitro experiments and computations performed on an idealized model of the left ventricle (LV) with a St. Jude Medical Regent heart valve in the aortic position.Particle Image Velocimetry (PIV) Flow Measurements of Carotid Artery Bifurcation with Application to a Novel Covered Carotid Stent Design
Stenosed carotid artery is responsible for 60% of strokes in the United States and is the third major cause of death. Recently, there is an increasing interest in carotid artery stenting for treatment of cervical carotid artery bifurcation atherosclerotic disease. The ultimate goal of this study is to develop, prototype, test, and optimize a novel design of a covered carotid stent, in order to achieve emboli prevention and...Manufacturing of patient-specific optically accessible airway models by fused deposition modeling
The purpose of this paper is to use rapid prototyping technology, in this case fused deposition modeling (FDM), to manufacture 2D and 3D particle image velocimetry (PIV) compatible patient‐specific airway models.In-vitro investigation of a potential wave pumping effect in human aorta
An impedance pump – also known as Liebau pump – is a simple valveless pump that operates based on the principles of wave propagation and reflection. It has been shown in embryonic zebrafish that a similar mechanism is responsible for the pumping action in the embryonic heart during the early stages before valve formation...Vortex Phenomena in Sidewall Aneurysm Hemodynamics: Experiment and Numerical Simulation
We carry out high-resolution laboratory experiments and numerical simulations to investigate the dynamics of unsteady vortex formation across the neck of an anatomic in vitro model of an intracranial aneurysm. A transparent acrylic replica of the aneurysm is manufactured and attached to a pulse duplicator system in the laboratory.Ventricular Contractility and Compliance Measured During Axial Flow Blood Pump Support: In Vitro Study
End-systolic elastance and end-diastolic compliance have been used to quantify systolic and diastolic function of the left ventricle (LV). In this study, the effective end-systolic elastance, (EES)eff, end-systolic volume intercept, (V0)eff, and end-diastolic compliance of the LV were assessed at various levels of left ventricular assist device (LVAD) support.A Physical Model of the Human Circulatory System for the Modeling, Control and Diagnostic of Cardiac Support Processes
In Vitro Evaluation of a Novel Hemodynamically Optimized Trileaflet Polymeric Prosthetic Heart Valve
Calcific aortic valve disease is the most common and life threatening form of valvular heart disease, characterized by stenosis and regurgitation, which is currently treated at the symptomatic end-stages via open-heart surgical replacement of the diseased valve with, typically, either a xenograft tissue valve or a pyrolytic carbon mechanical heart valve.Tubular Heart Valves from Decellularized Engineered Tissue
A novel tissue-engineered heart valve (TEHV) was fabricated from a decellularized tissue tube mounted on a frame with three struts, which upon back-pressure cause the tube to collapse into three coapting "leaflets." The tissue was completely biological, fabricated from ovine fibroblasts dispersed within a fibrin gel,...Hemodynamics in the Valsalva Sinuses after Transcatheter Aortic Valve Implantation (TAVI)
BACKGROUND AND AIM OF THE STUDY: The study aim was to assess, in vitro, the hemodynamic modifications produced by transcatheter valves in the Valsalva sinuses, by mean of phase-resolved particle image velocimetry (PIV) measurements...Role of the sinuses of Valsalva on the opening of the aortic valve
The present in vitro study was designed to ascertain whether the presence of sinuses of Valsalva in the aortic root were able to regulate the valve effective orifice area and modulate the gradient across the valve independently from root compliance.In-Vitro Calcification Study of Polyurethane Heart Valves
Tri-leaflet polyurethane heart valves have been considered as a potential candidate in heart valve replacement surgeries. In this study, polyurethane (Angioflex(®)) heart valve prostheses were fabricated using a solvent-casting method to evaluate their calcification resistance. These valves were subjected to accelerated life testing (continuous opening and closing of the leaflets) in a synthetic calcification solution. Results showed that Angioflex(®) could be ...DURABLE HIGH STRENGTH POLYMER COMPOSITES SUITABLE FOR IMPLANT AND ARTICLES PRODUCED THEREFROM
Left ventricle phantom and experimental setup for MRI and echocardiography–Preliminary results of data acquisitions
… 1 – Vivitro SuperPump, 2 – Vivitro controller, 3 – PC, 4 – constant pressure container, 5 – a phantom tank, 6 – the LV phantom, 7 – the body coil. … The phantom was deformed by a pump for hemodynamic simulations (SuperPump, Vivitro, Canada).Simulating the Dynamics of an Aortic Valve Prosthesis in a Pulse Duplicator: Numerical Methods and Initial Experience
… Department of Cardiothoracic Surgery, New York University School of Medicine. Lawrence Scotten ViVitro Systems, Inc. 1 Corresponding author. Manuscript received September 25, 2013; final manuscript received October 8, 2013; published online December 5, 2013.A Bio-Inspired Approach for the Reduction of Left Ventricular Workload
… doi:10.1371/journal.pone.0087122.g001. The left ventricle was simulated by a piston-in-cylinder pump (ViVitro Labs Inc. … The signals were collected using the Tri-pack pressure measuring systems (TP8891, Vivitro Labs Inc.).IMPLANTABLE PROSTHETIC VALVES AND METHODS
… The ventricular sac was suspended over a plexiglas atria 204 to be free-floating inside a rigid, water-filled, container made from plexiglas (not shown) and connected to a hydraulic pump system (Superpump system; Vivitro Systems Inc., Victoria, BC, Canada—not shown). …A Wave Dynamics Criterion for Optimization of Mammalian Cardiovascular System
A piston-in-cylinder pump (ViVitro Labs Inc. SuperPump System: Model … DPT-400). Tri-pack pressure measuring systems TP8891 (Vivitro Labs Inc.) consisting of three bridge amplifiers were used to collect the signals. Volume …An in vitro model of aortic stenosis for the assessment of transcatheter aortic valve implantation
A metric for the stiffness of calcified aortic valves using a combined computational and experimental approach
Design considerations and quantitative assessment for the development of percutaneous mitral valve stent
… The ventricular chamber was connected to a program-controlled piston pump (Vivitro Superpump, AR Series). The piston’s movement dilates and contracts the transparent silicone sac (ie left ventricle) to mimic the beating ventricle. …Development and characterization of acellular porcine pulmonary valve scaffolds for tissue engineering
… testing. The flow simulator has been described previously. 27 It mimicked the right heart and was controlled and monitored by the ViviTest software (Vivitro Systems Inc). The simulator was set up as described by Korossis et al. …Power Consumption of Rotary Blood Pumps: Pulsatile Versus Constant‐Speed Mode
The magnetically levitated rotor makes it feasible to modulate the pump speed without concern for contact-bearing friction that can impede rotation. The pump was connected to a commercial LV simulator (ViVitro Systems, Victoria, BC, Canada), schematically illustrated in Fig. …Validation of a numerical FSI simulation of an aortic BMHV by in vitro PIV experiments
A recirculating hydraulic circuit is developed consisting of a pulse duplicator system (Vivitro Labs Inc, Victoria, Canada) for imposing pulsatile flow, the acrylic test section for mounting the valve prosthesis, a Windkessel chamber for mimicking arterial compliance, a peripheral …A novel flow performance metric for the assessment of prosthetic heart valves
METHODS A commercially available heart simulator (Vivitro Heart system: SD2001-1) was utilized in this study as shown in Figure 2. This system has been utilized in previous studies supporting its efficacy and implementation [9-12]. … FIGURE 2 VIVITRO HEART SIMULATOR …LEAFLET AND VALVE APPARATUS
… The flow pulse duplicator system included the following components supplied by VSI ViVitro Systems Inc., Victoria BC, Canada: a Super Pump, Servo Power Amplifier Part Number SPA 3891; a Super Pump Head, Part Number SPH 5891 B, 38.320 cm2 cylinder area; a valve …The Effects of Positioning of Transcatheter Aortic Valve on Fluid Dynamics of the Aortic Root
… Experimental setup Pulsatile pump system: The heart-flow simulator consists of a hydraulic pump system (Superpump system, VSI, SPS3891, Vivitro systems Inc., Victoria, BC, Canada), which operates based on a VSI Wave Generator VG2001 (Vivitro Systems Incorporated, …