ANALYSIS OF SHEARING STRESS IN THE LIMITED DURABILITY OF BOVINE PERICARDIUM USED AS A BIOMATERIAL

The objective of the study was to determine the shearing stress exerte d by the suture th read under conditions of normal working stress. Thi rty-six samples of calf pericardium, similar to that employed in the m anufacture of bioprosthetic cardiac valve leaflets, were subjected to tensile testing. Prior to the trial, a continuous suture was sewn in t he central zone of each sample, at a 45 degrees angle to the longest a xis of the sample, using commercially-available threads (silk, Gore-Te x, Surgilene and nylon). Application of the Mohr circle for combined w ear revealed that the shearing stress ranged between 2.68-fold greater (for samples sewn with silk) and 5.48-fold greater (for samples sewn with nylon) than the working tensile stress in the region of the sutur e. It is concluded that the shearing stress is responsible for the lim ited durability of sutured samples of calf pericardium prepared to sim ulate bioprosthetic cardiac valve leaflets. (C) 1998 Chapman & Hall.