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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.

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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...

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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.)...

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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...

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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.

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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...

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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...

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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.

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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.

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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.

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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).

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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.

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Baruch B. Lieber1, Veronica Livescu, L. N. Hopkins and Ajay K. Wakhloo; Annals of Biomedical Engineering: 30, Issue 6; 768-777; 2002.

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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.

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Experiments in Fluids: 33, Issue 3; 458-463; 2002.

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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.

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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.

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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.

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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,...

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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.

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