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Research Papers

Hydrodynamic Evaluation of a Minimally Invasive Heart Valve in an Isolated Aortic Root Using a Modified In Vitro Model

[+] Author and Article Information
Qiang Wang

Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, EC 2610, Miami, FL 33174qwang004@fiu.edu

Fernando Jaramillo

Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, EC 2610, Miami, FL 33174fernando_jaramillo_a@yahoo.com

Yasushi Kato

 Innovia LLC, 12415 Southwest 136th Avenue, Miami, FL 33186ypkato@innovia-llc.com

Leonard Pinchuk

 Innovia LLC, 12415 Southwest 136th Avenue, Miami, FL 33186len@innovia-llc.com

Richard T. Schoephoerster

College of Engineering, University of Texas at El Paso, 500 West University Avenue, Engineering Building M-305, El Paso, TX 79968-0517schoephoerster@utep.edu

J. Med. Devices 3(1), 011002 (Jan 05, 2009) (6 pages) doi:10.1115/1.3054378 History: Received May 22, 2008; Revised November 20, 2008; Published January 05, 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. The purpose of this study is to verify its hydrodynamic performance and migration characteristics to assess its feasibility for use as a replacement heart valve. Hydrodynamic evaluation of the novel stent-valve combination device was carried out using a Vivitro left heart simulator and by setting up a comparison with the same 19 mm trileaflet valve under a traditional implantation (suture) method. To assess implantation ability under normal physiological conditions, porcine aortic root tissue was mounted into the left heart simulator to replace the original glass sinus. A comparison experiment was conducted to study the change in the total compliance and resistance of the testing system using the modified Windkessel model. For the range of test conditions investigated, the stent-valve combination device produced an average pressure gradient of 41.2mmHg(±19.6mmHg), an average effective orifice area (EOA) of 1.06cm2(±0.08cm2), and an average regurgitation percentage of 4.5% (±3.3%), while the sutured valve produced an average pressure gradient of 48.7mmHg(±17.4mmHg), an average EOA of 0.88cm2(±0.14cm2), and an average regurgitation percentage of 0.8% (±0.4%). The total compliance and resistance of the system was 0.37ml/mmHg(±0.01ml/mmHg) and 1.1mmHg/ml/s(±0.29mmHg/ml/s), with the original Windkessel model, and 0.33ml/mmHg(±0.01ml/mmHg) and 1.1mmHg/ml/s(±0.24mmHg/ml/s) for the system with the aortic tissue. The stent-valve combination device has demonstrated favorable hydrodynamic performance when compared with the same trileaflet valve under the traditional suturing method, and the arterial stent makes it possible to secure the valve at its required position without migration.

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Copyright © 2009 by American Society of Mechanical Engineers
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Figures

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Figure 1

The stent-valve combination device

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Figure 2

Schematic of the delivery device

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Figure 3

The porcine aortic tissue

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Figure 4

Schematics of the aortic root assembled to the Vivitro testing system. The locations of the ports for pressure and flow measurements are shown in relation to the valve position.

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Figure 5

Typical pressure and flow waveforms showing (a) left ventricular pressure (mm Hg), (b) aortic pressure (mm Hg), and (c) aortic flow (l/min). The cycle rate was 70 beats/min and the CO was 6 l/min.

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Figure 6

A comparison of the mean pressure gradient as a function of mean systolic flow for the stent-valve and the sutured valve

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Figure 7

A comparison of the EOA as a function of cardiac output for the stent-valve and the sutured valve

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Figure 8

A comparison of the mean regurgitation percentage as a function of cardiac output for the stent-valve and the sutured valve

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