Professional standards review organizations and their implications for physicians. II. Thromboembolism on mitral valve prosthesis

Although improvements in surgical technique, prosthetic design, and anticoagulant therapy have decreased the initial high incidence of thrombosis, thromboembolism, and excessive overgrowth causing valve dysfunction, these complications of prosthetic valve replacement continue to be potential hazards. Some investigators have further reduced the incidence of thromboembolism by covering exposed metal surfaces with fabric to anchor the extensions of pannus formation over the metal/fabric interface. This has been accomplished at the expense of reduction in flow area.For the past 3 years we have directed our efforts at minimizing the extent of tissue deposit on fixation rings by coating the Teflon fabric with a polyurethane film.^* Previous clinical use of polyurethane-filmed Teflon trileaflet valves between 1959 and 1962, and recent experimental evidence, indicated that the filming technique materially reduces or prevents tissue deposition on Teflon fabric. Since January, 1972, all fabric fixation rings have been filmed with polyurethane; during this period of observation there has been no incidence of thrombosis, thromboembolism, or valve dysfunction from excessive tissue overgrowth. The use of polyurethane filming may prove to be a valuable adjunct in avoiding or reducing potential hazards in prosthetic replacement surgery in the future.