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An improved implementation of block matching for motion estimation in ultrasound imaging
, FM Cardoso, SS Furuie - Proc. of SPIE Vol, 2017
Ultrasound elastography has become an important procedure that provides information about the tissue dynamics and may help on the detection of tissue abnormalities. We propose a novel algorithm to perform speckle tracking, which consists in an implementation of 2D Block Matching with two enhancements: sub-pixel linear interpolation and displacement propagation, which are able to increase resolution, reduce computation time and prevent kernel mismatching errors.
... studies on their numerical analogs. Fig. 1 Section of the f20dX LV phantom. Dimensions in [mm]. METHODS Fig. 2 Experimental setup. 1 – GE Vivid 6 scanner; 2 – water tank; 3 – LV model; 4 – M4S-RS probe; 5 – windkessel; 6 – Vivitro Superpump; 7 – Pump Controller; 8 – PC. ...
In-vitro investigation of coronary atherosclerosis on a modified vivitro system
, Lim, Brian. Muhammad Mujahid. Tan, Rong Wang. Arunkumar, U. Singapore Polytechnic School of Mechanical and Aeronautical Engineering
Coronary heart disease (CHD) is a common cardiac disorder in which a portion of the coronary artery is blocked, leading to a potential heart attack. Timely and accurate evaluation of suspected CHD patients is critical. Computer Tomography Angiography (CTA)... In order to streamline the evaluation of suspected CHD patients, we propose to create a more accurate and consistent diagnostic method of interpreting CTA results.
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 ...
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. ...
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). ...
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). ...
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 ...
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). ...
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.
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 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.
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. ...
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 ...
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).
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).
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. ...
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.
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.
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...
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.
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.
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.
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.
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.
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.
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....
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.
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...
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.
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.
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.
Accurate quantification of steady and pulsatile flow with segmented k-space magnetic resonance velocimetry
, Experiments in Fluids: 33, Issue 3; 458-463; 2002.
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.
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
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...
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.
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.
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.
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.
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...
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 ...
A flowmeter for unsteady liquid flow measurements in total liquid ventilation
, A Beaulieu, E Foucault, P Braud… - … (MeMeA), 2011 IEEE …, 2011 - ieeexplore.ieee.org
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...
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.
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
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,...
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 …
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. …
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, …