Comparison of late degenerative changes in porcine bioprostheses in the mitral and aortic valve position in the same patient.

Porcine bioprostheses implanted in both the mitral and aortic valve positions simultaneously in 5 patients aged 20 to 61 years (mean 45) were reexamined 18 to 107 months (mean 51) later. In 4 patients, the degenerative changes were distinctly more severe in the bioprostheses in the mitral than in the aortic valve position.