BIOPROSTHETIC VALVULAR FAILURE - CLINICAL AND PATHOLOGICAL OBSERVATIONS IN AN EXPERIMENTAL ANIMAL-MODEL

  • 1 January 1982
    • journal article
    • research article
    • Vol. 83  (4) , 618-631
Abstract
The clinical, hemodynamic and morphological findings in 18 young sheep in which porcine valvular bioprostheses (8 animals) and bovine pericardial bioprostheses (10 animals) were implanted in the tricuspid position. At the time of terminal elective studies (mean of 5.2 .+-. 0.2 mo. after implantation), 6 animals had ascites, 16 had hepatic congestion and 4 had bioprosthetic valvular infection. Hemodynamic studies (n = 10) showed that the tricuspid transvalvular mean diastolic gradients were not different at implantation and at termination of the study (4.7 .+-. 0.8 vs. 4.9 .+-. 0.9 mm Hg); tricuspid valve end-diastolic gradients increased from 1.2 .+-. 0.6 to 3.9 .+-. 0.5 mm Hg (P < 0.01). Each of the 18 valves had calcific deposits. Quantitative studies revealed that implanted porcine valvular bioprostheses (n = 7) contained a mean of 323 .+-. 165 mg of Ca/g of dry weight of cuspal tissue, in contrast to 0.2 mg/g in unimplanted porcine valvular bioprostheses. Similarly, implanted bovine pericardial bioprostheses (n = 6) contained a mean of 421 .+-. 115 mg of Ca/g of dry weight of cuspal tissue, in contrast to 0.3 mg/g in unimplanted bovine pericardial bioprostheses. Morphological findings in both types of bioprostheses included calcific deposits, collagen degeneration, leaflet immobilization and retraction, and fibrous sheaths. The latter were more extensive in bovine pericardial bioprostheses than in porcine valvular bioprostheses. The pathological alterations which develop in bovine pericardial bioprostheses are generally similar to those in porcine valvular bioprostheses, but may be more severe; these alterations lead to physiological and clinical sequelae similar to those of bioprosthetic valvular failure in human subjects; and young sheep constitute an excellent experimental model for in vivo testing of bioprosthetic cardiac valves.