Late tears in leaflets of porcine bioprostheses in adults.

Of 836 patients with a mitral or aortic bioprosthesis who were followed over an 8-year period, 32 required reoperation for prosthetic dysfunction. Of the 26 prostheses removed at operation, 18 (12 mitral and 6 aortic prostheses) showed tears in the valve leaflets. In 7 of the 12 patients with rupture of "mitral" leaflets and in 1 of the 6 patients with torn "aortic" leaflets, the onset of symptoms was sudden, requiring urgent reoperation. Two of the 18 patients died early after reoperation; both had progressive disability and underwent elective operation. In 5 of the 7 patients with torn leaflets in a mitral prosthesis who had acute onset of symptoms, a single tear was found and no gross evidence of calcification was detected. Macroscopic calcification was found in only 8 of the 18 (44.4%) prostheses with torn leaflets (mitral and aortic). Microscopic examination revealed calcific deposits in 9 of the 12 mitral and in all of the aortic bioprostheses. Of the 54 leaflets examined, 29 had tears: 10 were type I; 6, type II; 7, type III; and 6, type IV. Tears in porcine valve leaflets are not an uncommon cause of dysfunction. These tears often lead to acute hemodynamic changes, particularly in the mitral position, and usually require emergency reoperation. They may occur in prostheses that appear grossly normal.