We studied 1222 patients, who underwent isolated valve replacement; 652 had single mitral (MVR) and 570 single aortic (AVR) replacement. The patients were classified by sex, age and etiology. In the MVR group, the patients received 126 mechanical prostheses, as follow: 49 Björk-Shiley (B-S); 71 Lillehei-Kaster (L-K); 6 Hall-Kaster (H-K) and 526 IMC cardiac prosteses from bovine pericardium (PBIMC). The postoperative follow-up was 95% to 100%. The hospital mortality was 21 % for L-K and 9,5% for PBIMC. The incidence of thrombosis and thromboembolism in events per 100 patients-year was 7.7; 5.6; 6.7 and 1.0 for B-S; L-K; H-K and PBIMC, respectively. The incidence of calcification and tears was 1.8 per 100 patients-years for PBIMC, and did not occur with mechanical prostheses. Only the patients with mechanical prosteses were anticoagulated. In the AVR group, the patients received 336 mechanical prostheses: 92 B-S; 112 L-K; 113 H-K and 234 PBIMC. The postoperative follow-up was 97% to 100%. The hospital mortality was 5.5% for mechanical group, and 2.6% for biological. The incidence of thrombosis and thromboembolism in events per 100 patients-year was 3.0 for B-S; 2.3 for L-K; 2.5 for H-K and 0.3 for PBIMC. Calcification, tear and mechanical failure was 0.54 per 100 patients-year for PBIMC and 0.38 per 100 patients-year for H-K. In the mechanical group, the patients received aspirin and dipiridamole, and 30% of them oral anticoagulants. The authors concluded that the survival, in general manner, isn't related with the type of prosthesis. The incidence of thrombosis and thromboembolism in higher with mechanical valves, and the rate of complications is lower with biological valves. Oral anticoagulation is forceable with mechanical prosthesis in MVR, but unessential in AVR. The bioprosthetic valves don't need anticoagulation. For these reasons, the authors employ by routine, mechanical prostheses for AVR, unless there were counterindications, and biologycal prostheses for MVR.
heart valves; heart valves; heart valves prostheses; heart valves