DEVELOPMENT AND EVALUATION OF A PLIABLE BIOLOGICAL VALVED CONDUIT .1.PREPARATION, BIOCHEMICAL-PROPERTIES, AND HISTOLOGICAL-FINDINGS

Different types of external valved conduits have been used for the rep air of complex congenital cardiac anomalies that may have otherwise be en inoperable. However, an ideal conduit has yet to be found due to co mplications such as stenosis, thrombosis, calcification of the valve a nd graft wall, and ''peeling'' of the neointima. To address those prob lems, a new extracardiac valved conduit made of bovine jugular vein wa s developed and evaluated in a preliminary animal study. Harvested bov ine vein containing a naturally existing valve was initially incorpora ted with protamine on the inner surface and then was cross-linked in d iglycidyl ether (DE). Fixation with DE allowed the vein and its leafle ts to retain a tissue-like elasticity. To provide antithrombogenicity to the graft, heparin was introduced into the lumen to bind ionically to the pre-entrapped protamine. The biological valved conduit of appro ximately 14 mm diameter was implanted from the right ventricle to pulm onary artery as bypass graft in three dogs. After implantation, the na tive main pulmonary artery was ligated between the anastomotic sites o f the bypass conduit. No anticoagulant or antiplatelet drugs were admi nistered after surgery. One DE-fixed valved conduit was retrieved at 3 months, and the others were removed at 5 months. Only small thrombus areas were found on the white luminal surfaces. The valves and the con duits maintained softness and pliability, similar to before implantati on. Additionally, the collagen content, shrink temperature, and tannin g index of this newly developed biological valved conduit before and a fter fixation were measured in the study. These preliminary results su ggest that the new valved conduit fixed with DE and heparinized on the lumen may help mitigate the problems observed in the currently availa ble conduits.