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Henry Ford Hospital Medical Journal

Abstract

The porcine bioprosthesis has been the prosthetic valve of choice at Henry Ford Hospital since October 1971. By 1979, 23 cases of degeneration had been seen, and the rate seven years after implantation was 16%. Now, with a ten-year follow-up, there are 41 degenerated valves. After seven years, the percent free of degeneration is 88%, (SE of 2% [standard error]); at eight years, 82% (SE of 2.9%,); at nine years, 80% (SE of 3.4%); and at ten years, the percent free of degeneration is 69% (SE of 6.5%,). There was no difference in degeneration between men and women, between aortic or mitral position, or between the valves which were or were not rinsed in antibiotics. The incidence of degeneration was significantly greater in patients under 35 years of age. Contrary to our expectations, the number of valves removed for degeneration has not increased linearly, although the number at risk has continued to rise. In 1977, we removed four valves for degeneration; in 1978, eight valves; in 1979, 77 valves; in 1980, five valves; and in 1981, ten valves. The duration of implantation for degenerated valves has increased from 56 months (SD [standard deviation] of 11 months) in 1977-78 to 77 months (SD of 19 months) in 1981. Analysis of cohorts from 1972,1973, 1974, all now followed for seven years, reveals that at seven years the percent free of degeneration for 1972 is 88% (SE of 4.4%,); for 1973, 83% (SE of 4.8%); and for 1974, 95% (SE of 2.6%). Although a difference is suggested, it is not yet statistically significant (p = .48) due to the small number of valves degenerating. The incidence of porcine bioprosthetic degeneration appears to be decreasing, possibly because valves manufactured later in the series are more durable.

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