FLEXURAL RIGIDITY OF THE COMMISSURE REGION OF THE AORTIC VALVE LEAFLET

摘要

Flexure is a major deformation mode of the aortic valve (AV) leaflet during valve function. The structure of the AV must thus allow for low flexural rigidity yet also be of sufficient strength to support large tensile loads during valve closure. It well known that the AV is a heterogeneous structure uniquely adapted to provide efficient valve function. Yet, unlike the tri-layered central leaflet region, the commissural region commissural region of the AV leaflet (Fig. 1) is composed of only a single layer of collagen fibers. The effect of this structural difference in the AV leaflets flexural rigidity and hence its function is unknown. Also, knowledge of the flexural rigidity of the AV leaflets can be used as design criteria in fabricating bioprosthetic and tissue engineered heart valve considering the fact that the commissural region is known to be a major site for porcine bioprosthetic failure. Yet, to our knowledge the mechanical properties of the AV leaflet in the commissural area have never been measured, due to its small size (3-5 mm). In the present study, we developed a straightforward, novel method for measuring the effective stiffness (E) of the AV leaflet in the commissural region. Our approach uses a customized bending device which flexes the leaflet tissue in a cantilever beam configuration. Porcine valve leaflet specimens were obtained in the commissural area and were tested by being bent as a cantilever beam in opposite directions. E was calculated for either direction using the developed method.