Experience with tissue heart valves.

Experience with tissue valves for heart valve replacement over the past seven years is presented and analyzed. Between February 1967 and March 1969, 87 patients had heart valves replaced with preserved heterologous aortic valves. Valve failure occurred in 19 of the 70 operative survivors. There are 45 long-term survivors with heterologous aortic valves; 10 have regurgitant murmurs and 35 have valves functioning normally. Microscopic examination of failed valves has shown that the heterologous aortic valve gradually becomes a mechanically vulnerable structure in a state of rejection. During the past five years. autologous and homologous fascia lata and heterologous pericardium, mounted on a support frame, were used in 241 patients (131 aortic, 103 mitral and seven tricuspid). The follow-up period for the fascia lata group was 40 to 62 months and for the pericardial group 7 to 39 months. There have been significant differences in valve function with regard to both the site of valve insertion and the type of tissue used. Pericardial valves in the aortic position have produced the best results and autologous fascial valves in the mitral position, the worst. Valve failure occurred in only six patients, all with autologous fascia in the mitral position. The incidence of thromboembolism in the entire series was very low even though anticoagulants were not used. Analysis of clinical and hemodynamic results has shown that preserved heterologous pericardium has the potential for an adequate heart valve substitute.