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An In Vitro Feasibility Study of the Influence of Configurations and Leaflet Thickness on the Hydrodynamics of Deformed Transcatheter Aortic Valve
, Wentao Feng, Xianda Yang, Yang Liu, Yubo Fan Artificial Organs, 24 February 2017
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
, Sharan Ramaswamy, Makensley Lordeus, Omkar V. Mankame, Lilliam Valdes-Cruz, Steven Bibevski, Sarah M. Bell, Ivan Baez, Frank Scholl: Cardiovasc Eng Tech (2016).
...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
, S. Hamed Alavi, Marc Soriano Baliarda, Noemi Bonessio, Lorenzo Valdevit, Arash Kheradvar: Annals of Biomedical Engineering First Online: 22 December 2016
...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
, Claudio Capelli, Chiara Corsini, Dario Biscarini, Francesco Ruffini, Francesco Migliavacca, Alfred Kocher, Guenther Laufer, Andrew M. Taylor, Silvia Schievano, Martin Andreas, Gaetano Burriesci, Claus Rath: Cardiovascular Engineering and Technology (2016). doi:10.1007/s13239-016-0284-8
...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
, Apoorva Girish, MD, Muralidhar Padala, PhD, Kanika Kalra, MD, Bryant V. McIver, MD, Ravi K. Veeraswamy, MD, Edward P. Chen, MD, and Bradley G. Leshnower, MD: Ann Thorac Surg. 2016 Dec;102(6):1925-1932. doi: 10.1016/j.athoracsur.2016.05.020. Epub 2016 Jul 15.
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
, Ahmad Falahatpisheha, Daisuke Morisawaa, Taraz T. Tooskyb, Arash Kheradvara Journal of Biomechanics Available online 16 November 2016
...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
, Keyvan Amini Khoiy, Dipankar Biswas, Thomas N Decker, Kourosh T Asgarian, Francis Loth and Rouzbeh Amini Circulation November 11, 2016, Volume 134, Issue Suppl 1
...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
, E. Foucaulta, S. Hubersona, P. Brauda, D. Coisneb European Journal of Mechanics-B/Fluids Available online 17 November 2016
...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 . 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
, Esmé J. Donselaar, MD, Andrew Holden, FRANZCR, EBIR, Aleksandra C. Zoethout, BSc, Clark J. Zeebregts, MD, PhD, Michel M. P. J. Reijnen, MD, PhD Journal of Endovascular Therapy Nov 17, 2016
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
, Antoine Vaesken, Christian Pidancier, Nabil Chakfe, Frederic Heim Biomedical Engineering / Biomedizinische Technik. ISSN (Online) 1862-278X, ISSN (Print) 0013-5585, DOI: 10.1515/bmt-2016-0083, September 2016
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
, Keyvan Amini Khoiy, Dipankar Biswas, Thomas N. Decker, Kourosh T. Asgarian, Francis Loth and Rouzbeh Amini; Journal of Biomechanical Engineering revised August 23, 2016
...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
, Munirah Ismail, Gideon Praveen Kumar, Foad Kabinejadian, Yen Ngoc Nguyen, Fangsen Cui, Edgar Lik Wui Tay, Hwa Liang Leo - Cardiovascular Engineering and Technology pp 1-16 First online: 29 June 2016
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)
, Onur Dur, Keif Fitzgerald, Paul Muller, Chris Parker Thoratec Corporation, Sunnyvale, CA company slide
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
, Cole Feagler, Zeeshan Syedain and Robert Tranquillo University of Minnesota College of Science and Engineering Poster Report
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
, Sean Guo-Dong Tan, Sangho Kim, Hwa Liang Leo Experiments in Fluids June 2016, 57:110
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
, John Davidson, Sangjin Ryu Journal of Visualization pp 1-9 First online: 30 May 2016
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
, Riccardo Toninatoa, Jacob Salmona, Francesca Maria Susin, Andrea Duccia, Gaetano Burriescia doi:10.1016/j.jbiomech.2016.05.027
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
, Bernhard M. Vennemann , Thomas Rösgen, Thierry P. Carrel, Dominik Obrist - Article Cardiovascular Engineering and Technology pp 1-13 First online: 13 May 2016
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
, Guo-Dong Sean Tan and Hwa Liang Leo - J. Med. Devices 10(2), 020910 (May 12, 2016) (3 pages)
... 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
, Koohyar Vahidkhah, Dan Cordasco, Mostafa Abbasi, Liang Ge, Elaine Tseng, Prosenjit Bagchi, Ali N. Azadani Annals of Biomedical Engineering pp 1-13 First online: 05 April 2016
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
, Simon Heide-Jørgensen, Sellaswasmy Kumaran Krishna, Jonas Taborsky, Tommy Bechsgaard, Rachid Zegdi and Peter Johansen J Biomech Eng 138(3), 034504 (Jan 29, 2016) (7 pages)
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
, Morgane Evin, Carine Guivier-Curien, Philippe Pibarot, Lyes Kadem and Régis Rieu
... 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
, Nandini Duraiswamy , Jason D. Weaver, Yasamin Ekrami, Stephen M. Retta, Changfu Wu Cardiovascular Engineering and Technology pp 1-13 First online: 10 February 2016
... 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
, Erwan Salauna, Anne-Sophie Zensesb, Morgane Evinb, Frédéric Collartd, Gilbert Habiba, Philippe Pibarote, Régis Rieub International Journal of Cardiology Available online 8 January 2016
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
, Joseph Calderan, Wenbin Mao, Eric Sirois and Wei Sun* Article first published online: 29 OCT 2015 DOI: 10.1111/aor.12589 Journal of Artificial Organs
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
, Joseph Calderan, Wenbin Mao, Eric Sirois and Wei Sun-- Artificial Organs article first published online: 29 OCT 2015 DOI: 10.1111/aor.12589
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
, Ikechukwu Okafor, Arvind Santhanakrishnan, Vrishank Raghav, Ajit Yoganathan- Journal of Biomechanical Engineering 10/2015;
...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
, Zeeshan Syedaina, Jay Reimera, Jillian Schmidta, Matthew Lahtic, James Berryc, Richard Biancoc, Robert T. Tranquillo - doi:10.1016/j.biomaterials.2015.09.016
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
, Andrea Salicaa, Giuseppe Pisanib, Umberto Morbiduccib, Raffaele Scaffaa, Diana Massaib, Alberto Audeninob, Luca Welterta, Lorenzo Guerrieri Wolfa and Ruggero De Paulisa - - European Journal of Cardio- Thoracic Surgery (2015), First published online: September 10, 2015
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
, Filippo Piatti, Francesco Sturla, Gil Marom, Jawaad Sheriff, Thomas E. Claiborne, Marvin J. Slepian, Alberto Redaelli, Danny Bluestein - Journal of Biomechanics, 2015 Published Online: August 21, 2015
... 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
, Jahren, Silje Ekroll; Heinisch, Paul Philipp; Wirz, Jessica; Winkler, Bernhard; Carrel, Thierry; Obrist, Dominik (31 March 2015). Hemodynamic Performance of Edwards Intuity Valve in a Compliant Aortic Root Model (In Press). In: IEEE EMBC 2015. Milano. 25.08.-29.08.2015.
...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
, Bernhard Vennemann, David Hasler, Silje E. Jahren, Thomas Rösgen, Thierry P. Carrel, Dominik Obrist - Heart Valve Society 1st Annual Meeting MAY 6-9, MONTE CARLO, MONACO, GRIMALDI FORUM
...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
, John C. Westerdale, Ronald Adrian, Kyle Squires, Hari Chaliki and Marek Belohlavek --The Open Cardiovascular Medicine Journal, 2015, 9, 62-68
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
, F Shu, S Vandenberghe, J Brackett, JF Antaki - Cardiovascular Engineering and Technology July 2015
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
, J Poree, D Garcia, B Chayer, J Ohayon, G Cloutier - Medical Imaging, IEEE Transactions on (Volume:PP , Issue: 99 )
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
, Ikechukwu U. Okafor, Arvind Santhanakrishnan, Brandon D. Chaffins, Lucia Mirabella, John N. Oshinski and Ajit P. Yoganathan - Journal of Cardiovascular Magnetic Resonance 2015, 17:51 doi:10.1186/s12968-015-0154-9
... 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
, GC D'Antonio, BV Weidner, S Rowe, O Pierrakos - Systems and Information Engineering Design Symposium (SIEDS), 2015
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
, JM Reimer, ZH Syedain, BHT Haynie, RT Tranquillo - Biomaterials, 2015
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
, Clara Seaman, Andrew McNally, Stephen Biddle, Lauren Jankowski, Philippe Sucosky Presented in part at the 2013 Biomedical Engineering Society Conference, September 2013, Seattle, WA, and at the 2013 ASME Summer Bioengineering Conference, June 2013, Sunriver, OR, USA
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
, M Ismail, F Kabinejadian, YN Nguyen, E Tay, S Kim… - Artificial Organs, 2015 Article first published online: 29 APR 2015 DOI: 10.1111/aor.12457
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
, Zbigniew Trawińskia, Janusz Wójcika, Andrzej Nowickia, Robert Olszewskib, Andrzej Balcerzaka, Emilia Frankowskac, Arkadiusz Zegadłoc, Paweł Rydzyńskic -Biocybernetics and Biomedical Engineering 27 March 2015
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
, Hoda Maleki, MASc, Shahrokh Shahriari, PhD, Michel Labrosse, PhD, Josep Rodés-Cabau, MD, Philippe Pibarot, PhD, FACC, FAHA, FESC, Lyes Kadem, PhD, Eng. -Canadian Journal of Cardiology 28 March 2015
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 ...
Normal physiological conditions maintain the biological characteristics of porcine aortic heart valves: an ex vivo organ culture study.
, Konduri S, Xing Y, Warnock JN, He Z, Yoganathan AP. - Ann Biomed Eng. 2005 Sep;33(9):1158-66.
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
, Burriesci G, Marincola FC, Zervides C. J Med Eng Technol. 2010 Jan;34(1):7-22. doi: 10.3109/03091900903261241
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
, D.M. Amatya, E.K. Longmire; Journal of Fluids and Structures Volume 26, Issue 2, February 2010, Pages 218–235
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
, Nicolas Brugger, MD, , Kerstin Wustmann, MD, Michael Hürzeler, BS, Andreas Wahl, MD, Stefano F. de Marchi, MD, Hélène Steck, RN, Fabian Zürcher, MD, Christian Seiler, MD, The American Journal of Cardiology Available online 3 February 2015
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
, Filippo Piatti1 , Francesco Sturla 1,2 , Thomas E. Claiborne3 , Danny Bluestein3 , Alberto Redaelli 1
Experimental procedures are commonly used to obtain an overall quantification of the fluid dynamic and thrombogenic performances of cardiovascular devices ... (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
, Hadi Daood Toeg, Ovais Abessi , Talal Al-Atassi, Laurent de Kerchove, Gebrine El-Khoury, Michel Labrosse, Munir Boodhwani, - Cardiovasc Surg, 2014
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.
, E Frankowska, Z Trawi; Poster No.: C-0473 Congress: ECR 2014 Type: Scientific Exhibit
... 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
, A Falahatpisheh, G Pedrizzetti, A Kheradvar; Experiments in Fluids November 2014, 55:1848
... 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
, Z Trawiński, J Wójcik, A Nowicki, A Balcerzak…
... 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.
, Azadani AN1, Jaussaud N, Matthews PB, Ge L, Chuter TA, Tseng EE., Interact Cardiovasc Thorac Surg. 2010 Jul;11(1):70-7. doi: 10.1510/icvts.2009.225144. Epub 2010 Apr 15.
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
, Francis Robicsek, MD, PhD, Mano J Thubrikar, PhD, American Journal of Cardiology Volume 84, Issue 8, Pages 944–946, October 15, 1999
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.
, Jhun CS1, Reibson JD, Cysyk JP., ASAIO J. 2011 Sep-Oct;57(5):407-13. doi: 10.1097/MAT.0b013e318229ca8d.
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?
, Francis Robicsek MD, PhD, Mano J. Thubrikar PhDb, Joseph W. Cook MDa and Brett Fowler RTb; The Annals of Thoracic Surgery: 77, Issue 1; 177-185.
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
, George P. Chatzimavroudis, PhD, John N. Oshinski, PhD, Roderic I. Pettigrew, MD, PhD, Peter G. Walker, PhD, Robert H. Franch, MD, Ajit P. Yoganathan, PhD; Journal of Magnetic Resonance Imaging: 8, Issue 3; 577 – 582.
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
, W.Lim; Journal of Biomechanics: 34, Issue 11; 1417-1427.
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:
, Ng, Kim-Gau; Ting, Choon-Meng; Yeo, Joon-Hock; Sim, Kwang-Wei; Peh, Wee-Leng; Chua, Ngak-Hwee; Chua, Ngak-Kwong; Kwong, Frank; Blood Pressure Monitoring: 9, Issue 3; 149-165.
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:
, M. Nobili, U. Morbiducci, R. Ponzini, C. Del Gaudio, A. Balducci, M. Grigioni, F. Maria Montevecchi, A. Redaelli; Journal of Biomechanics: 41, Issue 11; 2539-2550.
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
, Scotten LN**, Walker DK**, Dutton JW; Journal of Heart Valve Disease: 11, Issue 3; 368 **ViVitro Labs Founder
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
, Simcha Milo, Edmond Rambodb, Chaim Gutfingerc and Morteza Gharibb; European Journal of Cardio-Thoracic Surgery: 24, Issue 3; 364-370.
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
, Poulsen, J.K. Kim, W.Y; IEEE Transactions on Biomedical Engineering: 43, Issue 6; 589-599.
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:
, Brant H. Maines, Christopher E. Brennen; Journal of Biomechanical Engineering: 127, Issue 4; 648.
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
, M. Labrosse, C. Beller, F. Robicsek, M. Thubrikar; Journal of Biomechanics: 39, Issue 14; 2665-2672.
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
, J. Timothy Baldwin*, Andy Campbell, Christopher Luck, William Ogilvie and Joe Sauter; European Journal of Cardio-Thoracic Surgery: 11, Issue 2; 287-292.
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
, G. Tansley, S. Vidakovic, and J. Reizes; Artificial Organs: 24, Issue 6; 483 – 487.
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
, Peacock J, Hankins S, Jones T, Lutz R. Journal of Biomechanics: 28, Issue 1; 17-26.
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
, Daniel Zimpfer MDa, Heinz Schima PhDb, Martin Czerny MDa, Marie-Theres Kasimir MDa, Sigrid Sandner MDa, Gernot Seebacher MDa, Udo Losert PhDc, Paul Simon MDa, Michael Grimm MDa, Ernst Wolner MD, PhDa and Marek Ehrlich MD; The Annals of Thoracic Surgery: 85, Issue 2; 470-473.
This study assessed the feasibility of stent graft treatment of ascending aortic dissections in a porcine in vitro model.
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:
, Nwosuh, I.A. Roberts, D. Kosiniski, S. Ciampa, S. Thomas, G.A.; Bioengineering Conference, 2005. Proceedings of the IEEE 31st Annual Northeast; 20- 21.
Epicardial Suction: A New Approach to Mechanical Testing of the Passive Ventricular Wall
, R. J. Okamoto, M. J. Moulton, S. J. Peterson; Journal of Biomechanical Engineering: 122, Issue 5; 479.
Doppler Echocardiographic Assessment of Valvular Regurgitation Severity by Measurement of the Vena Contracta: An In Vitro Validation Study
, J.Mascherbauer, R.Rosenhek, B.Bittner, J.Binder, P.Simon, G.Maurer, H.Schima, H.Baumgartner; Journal of the American Society of Echocardiography: 18, Issue 10; 999-1006.
Does Post-Stenotic Dilatation Enhance Collateral Flow?
, M. Thubrikar, F. Robicsek, B. Fowler, Y. Sun, Y. Lan Zhu, J. Holleman, Jr., T. Roush; Annals of Vascular Surgery: 18, Issue 5; 578-588.
Discriminant Analysis Of Acoustic Emissions From Bjork-Shiley Heart Valves With And Without Broken Minor Struts
, Walker**, D.K. Scotten**, L.N.; Engineering in Medicine and Biology Society: 13; 2107-2108. **ViVitro Labs Founder
Design of a Sterile Organ Culture System for the Ex Vivo Study of Aortic Heart Valves:
, James N. Warnock, Suchitra Konduri; Journal of Biomechanical Engineering: 127, Issue 5; 857.
Blood Flow in Distal End-to-side Anastomoses with PTFE and a Venous Patch: Results of an In vitro Flow Visualisation Study
, European Journal of Vascular and Endovascular Surgery: 18, Issue 3; 191-200.
Arteriovenous fistulas aggravate the hemodynamic effect of vein bypass stenoses: An in vitro study
, T.Nielsen, C.Djurhuus, E.Pedersen, J.Laustsen, J.Hasenkam, T.Schroeder; Journal of Vascular Surgery: 24, Issue 6; 1043-1049.
Angiographic Quantification of Contrast Medium Washout from Cerebral Aneurysms after Stent Placement
, Chander Sadasivana, Baruch B. Lieberc, Matthew J. Gounisc, Demetrius K. Lopese and L. N. Hopkinsb; American Journal of Neuroradiology: 23; 1214-1221.
Acute and Chronic Swine Rete Arteriovenous Malformation Models: Hemodynamics and Vascular Remodeling
, A. K. Wakhlooa, B. B. Liebera, R. Siekmannc, D. J. Ebera and M. J. Gounisa; American Journal of Neuroradiology: 26; 1702-1706.
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
, C. C. M. Rindt, A. A. van Steenhoven, J. D. Janssen a and G. Vossers; Journal of Fluid Mechanics: 226; 445-474; 1991.
Discrimination in vitro between the acoustic emissions from Bjork-Shiley convexo-concave valves with and without a broken minor strut
, D. K. Walker** and L. N. Scotten**; Medical and Biological Engineering and Computing: 29, Issue 5; 457-464; 1991. **ViVitro Labs Founder
In Vitro Strain Measurement of a Mechanical Heart Valve in a Pulse Simulator
, Teoh, S. H.; Lee, K. H.; Nugent, A. H.; Goh, K. S.; ASAIO Journal: 39, Issue 4; 1993.
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:
, David K. Walker PhD**, Lawrence N. Scotten**: J Heart Valve Dis, Vol. 3 No. 5 Sep. 1994. **ViVitro Labs Founder
The effects of dynamic cardiac compression on ventricular mechanics and energetics: Role of ventricular size and contractility
, Osamu Kawaguchi, MD, Yoichi Goto, MD, Shiho Futaki, MD, Yuichi Ohgoshi, MD, Hitoshi Yaku, MD, Hiroyuki Suga, MDa; The Journal of Thoracic and Cardiovascular Surgery: 107; 850-859; 1994.
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:
, Mano J. Thubrikar, PhD, Francis Robicsek, MD, Brett L. Fowler, BS; The Journal of Thoracic and Cardiovascular Surgery: 107; 707-716; 1994.
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:
, M. Strüber, A. Campbell, G. Richard and J. Laas; European Journal of Cardio-Thoracic Surgery: 10, Issue 6; 422-427; 1996.
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
, Importance of pressure recovery: Russell S. Heinrich, Arnold A. Fontaine, Randall Y. Grimes, Aniket Sidhaye, Serena Yan1, Kristin E. Moore, Robert A. Levine and Ajit P. Yoganathan; Annals of Biomedical Engineering: 24, Issue 6; 685-694; 1996.
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
, George P. Chatzimavroudis, Peter G. Walker, John N. Oshinski, Robert H. Franch, Roderic I. Pettigrew and Ajit P. Yoganathan; Annals of Biomedical Engineering: 25, Issue 4; 644-652; 1997.
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
, Osamu Kawaguchi, MDa, Yoichi Goto, MDb, Yuichi Ohgoshi, MDb, Hitoshi Yaku, MDb, Mitsuya Murase, MDa, Hiroyuki Suga, MDc; The Journal of Thoracic and Cardiovascular Surgery: 113; 923-931; 1997.
Correlation of radionuclide and optical tracer assessments of fluid flow in artificial ventricles
, M L J Rose, G A Wright, T G Mackay, W Martin and D J Wheatley; Physiological Measurement: 18; 171-182; 1997.
Anterior and posterior left ventricular sarcomere lengths behave similarly during ejection:
, J. M. Guccione, W. G. O’Dell, A. D. McCulloch and W. C. Hunter; American Journal of Physiology: 272; 1997.
Fluid dynamics of the CarboMedics kinetic bileaflet prosthetic heart valve
, JT Baldwin, A Campbell, C Luck, W Ogilvie and J Sauter; Eur J Cardiothorac Surg 1997;11:287-292.
Assessment of Small-Diameter Aortic Mechanical Prostheses
, Richard H. Marcus, MBBCh; Russell S. Heinrich, BSE; James Bednarz, BS; Stephen Lupovitch, MD; Joseph Abruzzo, MD; Raphael Borok, MBBCh; Byron Vandenberg, MD; Richard E. Kerber, MD; William Piccione, MD; Ajit P. Yoganathan, PhD; Roberto M. Lang, MD; American Heart Association: 98; 866-872; 1998.
Accuracy of Arterial Pulse-Wave Velocity Measurement Using MR
, Bradley D. Bolster, Jr, MSE, Ergin Atalar, PhD, Christopher J. Hardy, PhD, and Elliot R. McVeigh, PhD; Journal of Magnetic Resonance Imaging: 8, Issue 4; 878–888; 1998.
Prosthetic heart valve evaluation by magnetic resonance imaging
, J. Michael Hasenkama, b, Steffen Ringgaardc, Kim Houlindb, René M. Botnard, Hans Stødkilde-Jørgensenc, Peter Boesigerd, Erik Morre Pedersena, b, c; European Journal of Cardio-Thoracic Surgery: 16; 300-305; 1999.
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
, Sheng-Jing Dong, Paul S. Hees, Wen-Mei Huang, Sam A. Buffer Jr., James L. Weiss, and Edward P. Shapiro; American Journal of Physiology: 277; 1999.
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. A. Sakhaeimanesh; Y. S. Morsi; Journal of Medical Engineering & Technology: 23, Issue 2; 63 – 68; 1999.
A Physical Model Describing the Mechanism for Formation of Gas Microbubbles in Patients with Mitral Mechanical Heart Valves
, Edmond Rambod, Masoud Beizaie, Michael Shusser, Simcha Milo and Morteza Gharib; Annals of Biomedical Engineering: 27, Issue 6; 774-792; 1999.
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
, Steven Goldstein, PhDa, David R. Clarke, MDb, Steven P. Walsh, PhDa, Kirby S. Black, PhDa, Mark F. O’Brien, MDc; The Annals of Thoracic Surgery: 70; 1962-1969; 2000.
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
, Peter G. Walker, K. Houlind, C. Djurhuus, W.Y. Kim, E.M. Pedersen; Magnetic Resonance in Medicine: 43, Issue 5; 726 – 733; 2000.
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
, M. J. Thubrikar; G. G. Gong; I. E. Konstantinov; G. A. Selim; B. L. Fowler; F. Robicsek; Journal of Medical Engineering & Technology: 24, Issue 4; 173 – 180; 2000.
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
, Yos S. Morsi; Journal of Artificial Organs: 3, Issue 2; 143-148; 2000.
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
, Yu, Yih-Choung; Boston, J. Robert; Simaan, Marwan A.; Miller, Phil J.; Antaki, James F.; ASAIO Journal: 47, Issue 3; 293-301; 2001.
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
, Makoto Arita, Kiyotaka Iwasaki, Mitsuo Umezu, Masanori Yoshida, Tetsuo Fujimoto, Hisayoshi Suma and Tadashi Isomura; Journal of Artificial Organs: 4, Issue 2; 131-137; 2001
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:
, Yos S. Morsi and Ali A. Sakhaeimanesh; Artificial Organs: 24, Issue 7; 564 – 574; 2001.
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
, George P. Chatzimavroudis; John N. Oshinski; Robert H. Franch; Peter G. Walker; Ajit P. Yoganathan; Roderic I. Pettigrew; Journal of Cardiovascular Magnetic Resonance: 3, Issue 1; 11 – 19; 2001.
Decellularized human valve allografts
, Ronald C. Elkins, MDa, Patti E. Dawson, BSb, Steven Goldstein, PhDb, Steven P. Walsh, PhDb, Kirby S. Black, PhDb; The Annals of Thoracic Surgery: 71; S428-S432; 2001.
A new aortic root prosthesis with compliant sinuses for valve-sparing operations
, Mano J. Thubrikar, PhDa, Francis Robicsek, MD, PhDa, Geoffrey G. Gong, MDa, Brett L. Fowler, BSa; The Annals of Thoracic Surgery: 71; S318-S322; 2001.
Ultrafast Flow Quantification With Segmented k-Space Magnetic Resonance Phase Velocity Mapping
, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White and George P. Chatzimavroudis; Annals of Biomedical Engineering: 30, Issue 1; 120-128; 2002.
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
, Natascha Simon-Kupilik, MDa, Heinz Schima, PhDb, Leopold Huber, MEb, Reinhard Moidl, MDa, Gerhard Wipplingerb, Udo Losert, MDc, Ernst Wolner, MDa, Paul Simon, MD; The Annals of Thoracic Surgery: 73; 455-459; 2002.
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
, Baruch B. Lieber1, Veronica Livescu, L. N. Hopkins and Ajay K. Wakhloo; Annals of Biomedical Engineering: 30, Issue 6; 768-777; 2002.
Hydrodynamic function of the second-generation mitroflow pericardial bioprosthesis
, Louise M. Jennings, MEngb, Abdusalam El-Gatit, MDa, Zsolt L. Nagy, PhDa, John Fisher, DEngb, Peter G. Walker, PhDb, Kevin G. Watterson, FRACS; The Annals of Thoracic Surgery: 74; 63-68; 2002.
Accurate quantification of steady and pulsatile flow with segmented k-space magnetic resonance velocimetry
, Experiments in Fluids: 33, Issue 3; 458-463; 2002.
Correlation Between Negative Near-Wall Shear Stress in Human Aorta and Various Stages of Congestive Heart Failure
, Morteza Gharib and Masoud Beizaie; Annals of Biomedical Engineering: 31, Issue 6; 678-685; 2003.
Value and limitations of aortic valve resistance with particular consideration of low flow–low gradient aortic stenosis: an in vitro study
, Julia Mascherbauera, Heinrich Schimab, Raphael Rosenheka, Martin Czernyc, Gerald Maurera and Helmut Baumgartnera; European Heart Journal: 25, Issue 9; 787-793; 2004.
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
, Haosen Zhang, Sandra S. Halliburton, Richard D. White and George P. Chatzimavroudis; Annals of Biomedical Engineering: 32, Issue 12; 1618-1627; 2004.
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:
, Vedi, Manmeet Singh; Texas A&M University; 2004.
What parameters affect left ventricular diastolic flow propagation velocity? in vitro studies using color m-mode doppler echocardiography
, Toshihiro Ogawa, Lawrence N Scotten,** David K Walker**, Ajit P Yoganathan, Renee L Bess, Cheryl K Nordstrom, and Julius M Gardin; Cardiovasc Ultrasound; 2005. **ViVitro Labs Founder
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
, Grigioni, Mauro; Daniele, Carla; Del Gaudio, Costantino; Morbiducci, Umberto; Balducci, Antonio; D’Avenio, Giuseppe; Barbaro, Vincenzo; ASAIO Journal: 51, Issue 3; 176-183; 2005.
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
, George P. Chatzimavroudis, Peter G. Walker, John N. Oshinski, Robert H. Franch, Roderic I. Pettigrew, Ajit P. Yoganathan, Ph.D.; Magnetic Resonance in Medicine: 37, Issue 4; 545 – 551; 2005
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
, Suchitra Konduri, Yun Xing, James N. Warnock, Zhaoming He and Ajit P. Yoganathan; Annals of Biomedical Engineering: 33, Issue 9; 1158-1166; 2005.
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. T
First Human Case of Retrograde Transcatheter Implantation of an Aortic Valve Prosthesis
, David Paniagua, MD, José A. Condado, MD, José Besso, MD, Manuel Vélez, MD, Bruno Burger, MD, Salvatore Bibbo, MD, Douglas Cedeno, MD, Harry Acquatella, MD, Carlos Mejia, BA, Eduardo Induni, MD, and R. David Fish, MD; Texas Heart Institute Journal: 32, Issue 3; 393–398; 2005.
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
, R. K. Kaminsky; H. J. Weber; A. P. Simons; S. Kallweit; K. Kramm; P. R. Verdonck; Computer Methods in Biomechanics and Biomedical Engineering: 8, Issue 4; 159 – 160; 2005.
Quantitative approach to aortic valve-sparing surgery
, Carsten J. Bellera, Michel R. Labrosseb, Francis Robicsek and Mano J. Thubrikar; Interactive Cardiovascular and Thoracic Surgery: 5; 526-530; 2006.
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
, Kaminsky, Radoslav; Kallweit, Stephan; Weber, Hans J.; Simons, Antoine P.; Verdonck, Pascal; ASAIO Journal: 52, Issue 2; 4A; 2006.
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
, Ashwin Prakash, MD, Ruchira Garg, MD, Edward N. Marcus, MSc, Glenn Reynolds, PhD, Tal Geva, MD, Andrew J. Powell, MD; Journal of Magnetic Resonance Imaging: 24, Issue 3; 676 – 682; 2006.
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
, Zhang, Pei; Yeo, Joon Hock; Hwang, N H. C.; ASAIO Journal: 52, Issue 4; 391-397; 2006.
Cavitation Behavior of Three Monoleaflet Valves Under Accelerated Testing
, Lo, Chi-Wen; Liu, Jia-Shing; Lu, Po-Chien; Hwang, Ned H; ASAIO Journal: 52, Issue 2; 1A; 2006.
Anticoagulation for An Artificial Liver Support Device, the I.M.P.A.C.T. System(Tm) (Intermittent Modular Plasma Adsorption of Cytokines and Toxins)
, Hillebrand, Donald J.; Pfeifle, John; Roberts, Craig; Lo, Takkin; Hay, Karen; Bull, Brian; Frederick, Todd; Gish, Robert G.; ASAIO Journal: 52, Issue 2; 10A; 2006.
An In Vitro Study of Changing Profile Heights in Mitral Bioprostheses and Their Influence on Flow
, Kheradvar, Arash; Kasalko, Jeff; Johnson, Derrick; Gharib, Morteza; ASAIO Journal: 52, Issue 1; 34-38; 2006.
Shear Stress Investigation Across Mechanical Heart Valve
, Zhang, Pei; Yeo, Joon Hock; Qian, Ping; Hwang, Ned H. C.; ASAIO Journal: 53, Issue 5; 530-536; 2007.
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:
, Arash Kheradvar and Morteza Gharib; Annals of Biomedical Engineering: 35, Issue 12; 2050-2064; 2007.
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
, Radoslav Kaminsky, Stephan Kallweit, Hans-Joachim Weber, Tom Claessens, Krzysztof Jozwik, and Pascal Verdonck; Artificial Organs: 31, Issue 12; 869 – 879; 2007.
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
, Kheradvar, Arash; Milano, Michele; Gharib, Morteza; ASAIO Journal: 53, Issue 1; 8-16; 2007.
Stentless Valves Treated by the L-Hydro Process in the Aortic Position in Sheep:
, Paulo C Santos, Luís R Gerola, Ivan Casagrande, Ênio Buffolo and David T Cheung; Asian Cardiovasc Thorac Ann ;15:413-417; 2007.
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
, Julia Mascherbauer, Christina Fuchs, Martin Stoiber, Heinrich Schima, Elisabeth Pernicka, Gerald Maurer and Helmut Baumgartner; European Heart Journal: 29, Issue 16; 2049-2057; 2008.
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. A. Sakhaeimanesh; Journal of Medical Engineering & Technology: 32, Issue 6; 434 – 439; 2008.
A Novel, Low Cost, Disposable, Pediatric Pulsatile Rotary Ventricular Pump For Cardiac Surgery that Provides a Physiological Flow Pattern
, Mazur, Daniel E.; Osterholzer, Kathryn R.; Toomasian, John M.; Merz, Scott I.; ASAIO Journal: 54, Issue 5; 523-528; 2008.
Hydrodynamic Evaluation of a Minimally Invasive Heart Valve in an Isolated Aortic Root Using a Modified In Vitro Model
, Qiang Wang, Fernando Jaramillo, Yasushi Kato, Leonard Pinchuk, and Richard T. Schoephoerster; J. Med. Devices 3, 011002, 2009.
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
, Arash Kheradvar and Morteza Gharib; Annals of Biomedical Engineering: 37, Issue 1; 2009.
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
, Ali N. Azadani, PhD, Nicolas Jaussaud, MD, Peter B. Matthews, BS, Liang Ge, PhD, T. Sloane Guy, MD, Timothy A.M. Chuter, MD, Elaine E. Tseng, MD.; Ann Thorac Surg 2009;88:1857-1863, Aug 11, 2009.
A method for the measurement of left ventricular overload for aortic valve insufficiency
, Travis BR, Fowler BL, Robicsek F.; J Heart Valve Dis. (5):499-506; Sep 18, 2009.
Development and evaluation of a novel artificial catheter-deliverable prosthetic heart valve and method for in vitro testing
, Thomas E. Claiborne, Danny Bluestein, Richard T. Schoephoerster, The International Journal of Artificial Organs, Vol. 32, no. 5, pp. 262-271; 2009.
Revisiting the Simplified Bernoulli Equation
, Jeffrey J. Heys, Nicole Holyoak, Anna M. Calleja, Marek Belohlavek and Hari P. Chaliki, The Open Biomedical Engineering Journal 4, 123-128; 2010.
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
, Mathias Vermeulen, Cedric Van Holsbeke, Tom Claessens, Jan W. De Backer, Peter Van Ransbeeck, Pascal Verdonck, 15th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 05-08 July, 2010
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
, Michel R. Labrosse, Keegan Lobo, Carsten J. Beller, Journal of Biomechanics 43, 1916–1922; 2010.
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
, Andrew D. Michaels MD, David Mester, Catheterization and Cardiovascular Interventions Vol. 77, issue 5, pages 726-732, April 2011.
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
, Minsuok Kim, Ciprian Ionita, Rekha Tranquebar, Kenneth R. Hoffmann, Dale B. Taulbee, Hui Meng, and Stephen Rudin Proc Soc Photo Opt Instrum Eng. Author manuscript; available in PMC February 8, 2011
Application of speckle tracking echocardiography in the assessment of left ventricular function. In vivo and in vitro studies
, R Olszewski - IPPT Reports on Fundamental Technological …, 2012 - yadda.icm.edu.pl
DURABLE MULTI-LAYER HIGH STRENGTH POLYMER COMPOSITE SUITABLE FOR IMPLANT AND ARTICLES PRODUCED THEREFROM
, WC Bruchman, CL Hartman - US Patent 20,120,323,315, 2012 - freepatentsonline.com
Product Development Cycle of a Surgical Device for Mitral Valve Repair and Surgical Training Simulator Development Plan for the Same
, A Saini - 2011 - conservancy.umn.edu
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
, S Fortini, S Espa, R Toninato, L Pacetti, G Querzoli… - assessment, 2012 - ltces.dem.ist.utl.pt
Optimization and Verification of a Novel Trileaflet Polymeric Prosthetic Heart Valve
, TE Claiborne III - dspace.sunyconnect.suny.edu
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
, N Saikrishnan, G Tamilselvan… - Transactions of the …, 2011 - researchgate.ne
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
, WC Bruchman, PD Gassler… - US Patent …, 2012 - freepatentsonline.com
Signal processing of heart signals for the quantification of non-deterministic events
, V Millette, N Baddour - Biomedical engineering online, 2011 - biomedcentral.com
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
, A Beaulieu, E Foucault, P Braud… - … (MeMeA), 2011 IEEE …, 2011 - ieeexplore.ieee.org
Rotary blood pump control using integrated inlet pressure sensor
, J Cysyk, R Newswanger… - … in Medicine and …, 2011 - ieeexplore.ieee.org
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
, O Bazan, JP Ortiz - Revista Brasileira de Cirurgia Cardiovascular, 2011 - SciELO Brasil
Valve-in-valve hemodynamics of 20-mm transcatheter aortic valves in small bioprostheses
, AN Azadani, N Jaussaud, L Ge, … - The Annals of thoracic …, 2011 - Elsevier
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
, F Robicsek, RF Padera Jr… - HSR proceedings in …, 2012 - ncbi.nlm.nih.gov
Importance of Shear in Prosthetic Valve Closure Dynamics
, LN Scotten**, R Siegel - The Journal of heart valve disease, 2011 - icr-heart.com **ViVitro Labs Founder
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.
, A Ducci, S Tzamtzis, M Mullen, G Burriesci - 2012 - ltces.dem.ist.utl.pt
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
, Matthias F. Menne; Devesh Amatya; Rob Fraser; Maximilian Kuetting; Ulrich Steinseifer; Gerry Wight - Journal of the American College of Cardiology; Volume 64, Issue 11_S, September 2014
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
, A Falahatpisheh, A Kheradvar - European Journal of Mechanics-B/Fluids, 2012 - Elsevier
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
, B Rahmani, S Tzamtzis, H Ghanbari, G Burriesci… - Journal of …, 2012 - Elsevier
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.
, S Ramaswamy, M Salinas, R Carrol… - Journal of visualized …, 2012 - europepmc.org
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
, S Tzamtzis, J Yap, M Mullen, G Burriesci - 2011 - discovery.ucl.ac.uk
A methodology of measuring coronary flow in a porcine aortic root using a pulsatile flow loop
, J Calderan, E Sirois, W Sun - … Conference (NEBEC), 2012 38th …, 2012 - ieeexplore.ieee.org
Experimental and Computational Studies of the Aortic Bi-leaflet Mechanical Heart Valve (BMHV) Hemodynamics in an Idealized Left Ventricle
, B Chaffin, L Mirabella… QScience Proceedings: Vol. 2012, Heart Valve Biology and Tissue Engineering, 64. DOI: 10.5339/qproc.2012.heartvalve.4.64 Published online: 10 Jul 2012
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
, F Kabinejadian, HL Leo, A Danpinid, - World Congress on …, 2013 - Springer
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
, M Vermeulen, T Claessens… - Rapid Prototyping …, 2013 - emeraldinsight.com
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
, Niema M. Pahlevana, Morteza Ghariba, - Journal of Biomechanics Volume 46, Issue 13, 3 September 2013, Pages 2122–2129
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
, Trung B. Le, Daniel R. Troolin, Devesh Amatya*, Ellen K. Longmire, Fotis Sotiropoulos - Annals of biomedical …, 2013 - Springer *ViVitro Labs employee
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
, Choon-Sik Jhun and Joshua P. Cysyk* – Artificial Organs Volume 38, Issue 4, pages 309–315, April 2014
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
, A Siewnicka, K Janiszowski, M Gawlikowski – Mechatronics 2013, 2014 – Springer
In Vitro Evaluation of a Novel Hemodynamically Optimized Trileaflet Polymeric Prosthetic Heart Valve
, M Kuetting, U Steinseifer, MJ Slepian, D Bluestein – researchgate.net, Journal of Biomechanical Engineering Copyright VC 2013 by ASME
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
, ZH Syedain, LA Meier, JM Reimer… – Annals of biomedical …, 2013 – Springer
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)
, A Ducci, S Tzamtzis, MJ Mullen… – J Heart Valve Dis. 2013 Sep;22(5):688-96.
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
, G Pisani, R Scaffa, O Ieropoli, EM Dell’Amico… – The Journal of Thoracic …, 2013 – Elsevier
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
, P Boloori_Zadeh, SC Corbett, H Nayeb-Hashemi – Materials Science and …, 2013 Science Direct
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
, WC Bruchman, PD Gassler, CL Hartman, PJ Walsh… – US Patent 20,130,325,117, 2013
Left ventricle phantom and experimental setup for MRI and echocardiography–Preliminary results of data acquisitions
, S Cygan, K Werys, Ł Błaszczyk, T Kubik, K Kałużyński – … and Biomedical Engineering, 2013
… 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
, BE Griffith, V Flamini, A DeAnda, L Scotten – Journal of Medical Devices, 2013
… 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
, NM Pahlevan, M Gharib – PLOS ONE, 2014
… 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
, A Kheradvar – US Patent 20,140,046,436, 2014
… 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
, NM Pahlevan, M Gharib – Journal of Biomechanics, 2014
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
, Journal of Biomechanical Engineering, doi:10.1115/1.4026576. H. Maleki, S. Shahriari, M. Labrosse, P. Pibarot and L. Kadem
A metric for the stiffness of calcified aortic valves using a combined computational and experimental approach
, Medical & Biological Engineering & Computing, January 2014, Volume 52, Issue 1, pp 1-8. H. Maleki, S. Shahriari, L. G. Durand, M. R. Labrosse, L. Kadem
Design considerations and quantitative assessment for the development of percutaneous mitral valve stent
, GP Kumar, F Cui, HQ Phang, B Su, HL Leo, JKF Hon – Medical Engineering & Physics, 2014
… 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
, J Luo, SA Korossis, SPP Wilshaw, LM Jennings… – Tissue Engineering, 2014
… 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
, T Pirbodaghi, C Cotter, K Bourque – Artificial Organs, 2014
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
, S Annerel, T Claessens, J Degroote, P Segers… – Medical Engineering & …, 2014
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
, DE Vargas, BV Weidner, GC D’Antonio, O Pierrakos – Systems and Information …, 2014
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
, WC Bruchman, CL Hartman – US Patent 20,140,163,671, 2014
… 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
, EM Groves, A Falahatpisheh, JL Su, A Kheradvar – ASAIO Journal, 2014
… 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, …