EVALUATION OF A HETEROLOGOUS PERICARDIUM IMMOBILIZED WITH HEPARIN AS A VASCULAR PATCH IN A CANINE MODEL

Heterologous pericardia, acquired from mammal, are often used as biolo gical patches in cardiovascular surgery for pericardial substitute, in tracardiac defect repair, stenosis enlargement, and change of blood st ream direction. However, these biological patches have been clinically encountered with thrombus formation and tissue adhesion, These concer ns may be overcome by immobilizing heparin on the surfaces of these bi ological patches. The study was to evaluate an epoxy-fixed porcine per icardium with ionically- or covalently-immobilized heparin implanted i n a canine model as a vascular patch, The nonheparinized counterpart w as used as a control, The results obtained suggested that surface-immo bilized heparin may reduce thrombus formation and tissue adhesion of i mplanted biological patches. Additionally, the porcine pericardium wit h covalently-immobilized heparin was relatively better than its ionica lly-immobilized counterpart: in reducing thrombus formation and tissue adhesion. Therefore, it is suggested that heparin be immobilized by s table covalent bond in clinical use. The resistance against in vivo de gradation for the heparinized tissues (ionically- or covalently-immobi lized) was relatively better than the nonheparinized tissue. However, heparinization did not seem to prevent the implanted biological tissue s from calcification.