COMPARISON OF THE COMPRESSIVE BUCKLING OF PORCINE AORTIC-VALVE CUSPS AND BOVINE PERICARDIUM

Background and aims of the study: Compressive buckling at sites of sha rp leaflet flexure has been implicated as a mechanism of failure in po rcine xenografts. The potential for such buckling to cause damage in n ew-generation pericardial valves, however, has not been examined, Meth ods: Clinical-grade bovine pericardium fixed in 0.625% glutaraldehyde was cut into 5 mm-wide strips, Fresh porcine aortic valve leaflets wer e fixed flat in 0.625% glutaraldehyde and 5 mm-wide circumferential st rips were cut, These tissues were bent to various curvatures, held ben t with sutures, histologically processed, and sectioned and stained wi th hematoxylin and eosin. Images of the specimens were acquired by com puter and the depth of compressive buckling, thickness of the specimen , and local curvature were measured. Results: Porcine tissue skewed a progressive increase ire depth of buckling as both thickness and curva ture increased, while bovine pericardium head minimal buckling rat all curvatures. Porcine tissues buckled to a mean (+/- SEM) fractional de pth of 0.23 +/- 0.012 while bovine pericardium buckled to only 0.09 +/ - 0.006. Conclusions: These data suggest that the internal fibrous str ucture of bovine pericardium may tolerate high bending curvatures bett er than porcine aortic valve leaflets when stiffened and cross-linked with glutaraldehyde. This nay explain the apparently good durability o f current generation pericardial valves.