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Technical Brief

An In Vitro Model of Aortic Stenosis for the Assessment of Transcatheter Aortic Valve Implantation

[+] Author and Article Information
Hoda Maleki, Lyes Kadem

Department of Mechanical and Industrial Engineering,
Laboratory of Cardiovascular Fluid Dynamics,
Concordia University,
Montreal, QC H3G 1M8, Canada

Shahrokh Shahriari

University of Montreal Hospital Research Center (CRCHUM),
Montreal, QC H2X 0A9, Canada;
Department of Mechanical and Industrial Engineering,
Laboratory of Cardiovascular Fluid Dynamics,
Concordia University,
Montreal, QC H3G 1M8, Canada
e-mail: lcfd@encs.concordia.ca

Michel Labrosse

Department of Mechanical Engineering,
University of Ottawa,
Ottawa, ON K1N 6N5, Canada

Philippe Pibarot

Quebec Heart and Lung Institute,
Laval University,
Quebec, QC G1V 0A6, Canada

1Corresponding author.

Manuscript received August 30, 2013; final manuscript received January 19, 2014; accepted manuscript posted January 27, 2014; published online April 10, 2014. Assoc. Editor: Jonathan Vande Geest.

J Biomech Eng 136(5), 054501 (Apr 10, 2014) (4 pages) Paper No: BIO-13-1396; doi: 10.1115/1.4026576 History: Received August 30, 2013; Revised January 19, 2014; Accepted January 27, 2014

A significant number of elderly patients with severe symptomatic aortic stenosis are denied surgical aortic valve replacement (SAVR) because of high operative risk. Transcatheter aortic valve implantation (TAVI) has emerged as a valid alternative to SAVR in these patients. One of the main characteristics of TAVI, when compared to SAVR, is that the diseased native aortic valve remains in place. For hemodynamic testing of new percutaneous valves and clinical training, one should rely on animal models. However, the development of an appropriate animal model of severe aortic stenosis is not straightforward. This work aims at developing and testing an elastic model of the ascending aorta including a severe aortic stenosis. The physical model was built based on a previous silicone model and tested experimentally in this study. Experimental results showed that the error between the computer-aided design (CAD) file and the physical elastic model was <5%, the compliance of the ascending aorta was 1.15 ml/mm Hg, the effective orifice area (EOA) of the stenotic valve was 0.86 cm2, the peak jet velocity was 4.9 m/s and mean transvalvular pressure gradient was 50 mm Hg, consistent with as severe. An EDWARDS-SAPIEN 26 mm valve was then implanted in the model leading to a significant increase in EOA (2.22 cm2) and a significant decrease in both peak jet velocity (1.29 m/s) and mean transvalvular pressure gradient (3.1 mm Hg). This model can be useful for preliminary in vitro testing of percutaneous valves before more extensive animal and in vivo tests.

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Copyright © 2014 by ASME
Topics: Valves , Aorta
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Figures

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Fig. 1

Model description: (a) dimensions of the model, (b) the original CAD model of the ascending aorta and the stenotic aortic valve, (c) the top, down, and side view of the physical model of the ascending aorta and the stenotic aortic valve, (d) the final model as installed in ViVitro pulse duplicator system, and (e) implantation of the transcatheter aortic valve

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Fig. 2

Aortic and left ventricle pressure waveforms obtained from the model at SV = 60 ml (a) before, and (b) after transcatheter valve implantation

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Fig. 3

Closed and open positions of (a) stenotic aortic valve model and (b) transcatheter aortic valve

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Fig. 4

Instantaneous geometric orifice area before and after the transcatheter valve implantation

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