Comparative hydrodynamic evaluation of bioprosthetic heart valves

Abstract

Background and aim of study: Pressure gradients across cardiac valve prostheses have been identified as one of the most important performance measures in valve replacement surgery. Specifically in aortic valves, these gradients influence reduction of left ventricular hypertrophy and are postulated to influence long-term survival. The correct choice of replacement valve is hampered by a lack of uniform measures of valve performance. The aim of this study was to compare in-vitro hydrodynamic performance of commercially available bioprosthetic valves under identical test conditions.

Methods: In-vitro steady forward flow and pulsatile flow tests were performed on aortic and mitral bioprosthetic valves in accordance with ISO/FDA guidelines at two different institutions to obtain objective hemodynamic performance measures. Measurements were recorded at various flow rates, flow and pressure to obtain mean pressure gradients and effective orifice areas (EOAs).

Results: Wide variation in pressure gradients was found among tested valves of each size. For a given size, differences of 200 to 400% were observed; in general, the valve models' relative rankings in pressure drop were independent of size.

Conclusion: The Carpentier-Edwards Perimount valve showed superior performance at all sizes tested. While the mean pressure gradients and EOAs reported by each institution differed for a given valve, the performance of valve models relative to each other was similar. The testing of valves under identical conditions is a valuable comparative indicator of valve hemodynamic performance.