UNLABELLEDTo observe the antithrambotic property of a new prosthetic made double bileaflet valve of all-pyrolytic carbon.

METHODFifteen sheeps underwent mitral valve replacement (MVR) with this new mechanical valve. Each animal was placed on cardiopulmonary bypass. All of the sheep were given in an anticoagulation protocol and followed for three months. Final studies were performed on all animals surviving for more than 12 weeks.

RESULTTen sheeps died within 48 h after operation, five sheeps survived. The long-term survivors were killed forautopsies, two sheeps were killed in the 1st week after operation, one in 12th weeks and two in 2.5 years. Pathological examination of 10 sheeps which died early after operation revealed that there was no either evidence of thromboembotic phenomenon, or any failures of the mechanical valve. Autopsy studies in the five long-term survivors revealed that the sewing ring was covered by a thin layer of microthrombi consisted most of platelets and fibrin in 1th week after operation. The sewing rings was covered by a tissue layer, with partial organized micro thrombi and endothelialization in 12th weeks after the operation. Two and half years after operation, the complete endothelialization presented around the sewing ring without restriction of bileaflet motion. The tissue ingrowth tends to stop at the pyrolytic carbon-fabric interface on both surfaces of left atrium and ventricle. This study demonstrated that the new prosthetic heart valve had not promoted thrombosis and thrombembolism.