The importance of collagen degradation in the failure of bioprosthetic heart valves

摘要

Although calcification is a well established major contributory pathology in the failure of porcine bio-prosthetic heart valves (BHV), mechanisms of structural deterioration of the valvular extracellular matrix are only beginning to beappreciated. Such changes can mediate tearing secondary to mineralization or cause cuspal defects or distortion in the absence of calcification. We have developed a working hypothesis that a major mechanism of BHV structural failure is damage to thevalvular structural matrix independent of calcification. This hypothesis is based on the fact that chemical pretreatment inhibits the dynamic structural rearrangements that occur during natural valve function (4). This immobility results in increasedflexural compressive stresses that induce delamination and fracture of the collagen fibers due to the large flexural strains during valve operation, leading to structural damage independent of calcification and ultimately valve failure.