Ostrich pericardium, a biomaterial for the construction of valve leaflets for cardiac bioprostheses: mechanical behaviour, selection and interaction with suture materials

The mechanical behavior of ostrich pericardium was studied for the purpose of assessing its utility in the construction of bioprosthetic cardiac valve leaflets. The tissue was tested biaxially using a hydraulic simulator that subjected it to increasing stress until rupture. One hundred eighty trials were performed, 36 with unsutured pericardium and four series of 36 trials each with pericardium sutured with silk, Prolene, nylon or Gore-Tex. The s amples were tested in pairs from three different pericardial regions. One s ample from each pair (the predictive specimen) was assessed according to mo rphological and mechanical criteria, while the other (the predicted or sele ctable specimen) was subjected only to morphological analysis. The findings show that ostrich pericardium treated with glutaraldehyde according to sta ndard methods has an excellent resistance to rupture in biaxial testing, wi thstanding stresses of up to 100 M Pa, and never lower than 30 M Pa. Its re sistance to rupture is lowered by suturing, a loss that is less pronounced when silk sutures are used. The results with Gore-Tex are very homogeneous and the elastic behavior of the pericardium/suture unit appears to be simil ar to that of unsutured tissue, suggesting that the interaction between the two biomaterials is minor. Similar results were observed in the series sut ured with Prolene and nylon. The use of paired samples makes it possible to closely estimate the mechanical behavior of the tissue in a given zone by determining that of its mate. The statistical study shows that this estimat ion is not conditioned by the suture employed, thus validating this approac h and providing more precise criteria for tissue selection. (C) 2001 Elsevi er Science Ltd. All rights reserved.