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Back to 2014 Annual Meeting Abstracts


Hemodynamic and Performance Measurements in Normal and Calcified Tricuspid and Bicuspid Aortic Valves
Clara Seaman, Philippe Sucosky.
University of Notre Dame, South Bend, IN, USA.

Background: The bicuspid aortic valve (BAV) is a congenital defect occurring in 1-2% of the population wherein the aortic valve forms with two leaflets instead of three. The BAV has a higher incidence of valve stenosis, calcification, aortic dilation, dissection, and aneurysm. It has been hypothesized that the abnormal hemodynamics resulting from this valvular defect significantly contribute to valvular dysfunction and failure. Therefore, this study's goal is to present a comparative in vitro assessment of the flow and energy loss in a tricuspid aortic valve (TAV) and type-I BAV under normal and calcified states. Methods: Four valve models were considered in this study. The TAV model used a normal porcine valve and could be modified into a type-1 BAV model by suturing the left- and right-coronary leaflets. The calcified valve models were fabricated by injecting a solution of hydroxyapatite and agarose into the valve leaflets. Flow downstream of the four valve models, which were mounted in a physiologically relevant geometry and subjected to physiologic flow and pressure conditions, was characterized using particle-image velocimetry. Valve performance was evaluated using clinical metrics. Results: The normal TAV exhibited a circular orifice while the BAV orifice exhibited an elliptical shape. The calcified models featured irregular orifice shapes and demonstrated a reduction of up to 50% in orifice area relative to their non-calcified counterparts. Both healthy valve models exhibited an energy loss index greater than 1.35 cm2/m2, which is associated with healthy valve performance, whereas the diseased counterparts were below the healthy valve threshold. There was a 29% increase in the peak velocity between the normal and calcified TAV. A similar increase was observed between the normal and calcified BAV. The TAV had the lowest shear stress while the calcified BAV exhibited the highest level of shear stress. Conclusions: This study demonstrated that, while the TAV and BAV hemodynamics may be different, the BAV is not inherently diseased. However, when calcification was added to the TAV and BAV, the valves behaved as clinically diseased valves and exhibited much higher velocities and stresses than their healthy counterparts.


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