Comparison of late (62 to 140 months) degenerative changes in simultaneously implanted and explanted porcine (Hancock) bioprostheses in the tricuspid and mitral valve positions in six patients.

A Hancock porcine bioprosthesis (PB) was simultaneously implanted in each of 6 patients aged 30 to 64 years (mean 45) in the tricuspid and mitral valve positions and both PBs were explanted 62 to 140 months (mean 102) later. Cuspal degenerative changes occurred in all 12 PBs. In 5 patients, the changes were more extensive on the PBs in the mitral position than in those in the tricuspid position. Cuspal calcific deposits, as determined by radiographs of the explanted bioprostheses, occurred in 5 PBs in the mitral position and in 3 in the tricuspid position: 1 patient with calcific deposits in the PB in the mitral position had no calcific deposits in the corresponding PB in the tricuspid position; 1 patient had heavy calcific deposits in the PB in the mitral position and only mild deposits in the PB in the tricuspid position; and 3 patients had similar but mild calcific deposits in both PBs. Cuspal tears occurred in 5 of the 6 PBs in the mitral position and in no PB in the tricuspid position. Thrombus was observed on the ventricular aspects of the bioprosthetic cusps in 1 PB in the mitral position and in 4 PBs in the tricuspid position. Thus, in our 6 patients, the degenerative changes were more extensive in the PBs in the mitral position than in those in the tricuspid position. These observations indicate that wear characteristics of simultaneously implanted PBs vary according to the site of implantation.