IN VIVO EXPERIMENTAL EVALUATION OF BIOPROSTHETIC CARDIAC VALVES.

During the past 4 years an animal model system has been developed in juvenile (10-15) week old sheep which permits early and late studies of host-prosthesis interactions. Over 300 porcine aortic valves (PAV) and bovine pericardial valves (BPV) have been implanted in the tricuspid (TVR) or mitral (MVR) positions. Long-term survival (30 days-1 year) in the last 200 animals has been greater than 90%. In analyzing the results obtained with valve implantations in this model system, emphasis has been given to: 1) early and late hemodynamic investigations of valve function; 2) pathologic alterations, including localization of calcific deposits; 3) quantitative analysis of valve calcification; 4) evaluations of treatment processes to decrease valve calcification; and 5) use of intracardiac Doppler/2-D echocardiography to study valve function.