Temporal changes in the surgical pathology of prosthetic aortic valves: a study of 157 cases spanning 26 years (1970-1995).

The objective of this study was to identify time-related changes in the types, functional states, and complications of explanted prosthetic aortic valves. All patients having a prosthetic aortic valve replacement at Mayo Clinic Rochester during the years 1970, 1975, 1980, 1985, 1990, and 1995 were identified. By reviewing the medical records and pathologic specimens, 157 valves were classified by type, functional state, complications, and duration of implantation. Among the 157 patients (118 men and 39 women), 48% had mechanical valves, 37% bioprostheses, 14% homografts, and 1% teflon trileaflet. Regurgitation was the most common functional state both overall (69%) and in each year. The mean age of patients at reoperation increased from 53 years in 1970 to 60 years in 1995, during which time the mean duration of implantation increased from 2.7 to 9.2 years. Although mechanical valves represented 70% of explanted aortic prostheses in 1970, they accounted for only 37% in 1995. The percentage of valves failing from structural degeneration decreased, from 58% in 1980 to an average of 36% thereafter, while the percentage for prosthetic aortic endocarditis increased from 0% in 1980 to an average of 19% during 1985, 1990, and 1995. Endocarditis affected men in 19 (83%) of the 23 cases and was caused by staphylococci or streptococci in 18 (78%). The development of newer prosthetic valves, changes in surgeons' preferences for them, and improvements in diagnosis, treatment, and prevention have contributed to temporal fluctuations in the relative frequencies of complications and associated functional states.