Calcific degeneration as the main cause of porcine bioprosthetic valve failure

Abstract

Sixty-seven glutaraldehyde-processed porcine bioprostheses (PBs), recovered at autopsy or reoperation from 65 patients, were evaluated by roentgenologic and pathologic examination. Seven patients with 8 PBs were younger than 20 years of age. The time interval of function was 2 to 138 months (average 62). Pathologically, 53 explants had signs of intrinsic dysfunction, which was ascribed to calcification in 36 (68%). By x-ray examination, calcific deposits were found in 55 of 67 PBs (82%). The mean duration of function was 70 ± 32 months in calcified PBs vs 27 ± 18 months in noncalcified PBs (p <0.001). All 26 PBs that had been in place for longer than 6 years were calcified. In 45 PBs the Ca ++ deposits were considered severe (mean time of function 76 ± 32 months) and mild in 10 (mean time of function 44 ± 22 months) (p <0.005). The Ca ++ deposits were located at the commissures in 54 PBs (98%), at the body of cusps in 41 (75 %), at the free margin in 37 (67 %) and at the aortic wall in 37 (67%). When mild, Ca ++ deposits involved the commissures in 90% of cases, the body of cusps in 30 % and the free margin only in 10%. Forty-seven calcified PBs were mounted on a flexible stent, and 8 had a rigid stent, with an average time of function of 63 ± 28 and 113 ± 18 months, respectively (p <0.00001). Ca ++ dysfunction occurred earlier in the aortic than in the mitral position (59 ± 19 vs 86 ± 35 months, p < 0.05). All the PBs explanted from young patients and 47 of 59 PBs removed from adult patients were calcified, with an average time of function of 50 ± 21 vs 73 ± 33 months, respectively (p < 0.05). The duration of PB in patients older than 35 years of age and in those aged 20 to 35 years was identical. Chronic anticoagulant therapy with warfarin did not influence the occurrence and severity of Ca ++ degeneration.