[Reoperation of primary tissue failure of bioprosthesis in the mitral position]

The surgical results of 38 patients who underwent reoperation for primary tissue failure of bioprosthesis in the mitral position between May 1982 and June 1990 were analyzed to determine the risk factors affecting the hospital mortality. The type of bioprostheses requiring reoperation were Hancock valve in 21 patients, Liotta valve in 15 patients and Mitroflow valve in 2 patients. Twenty-five preoperative and perioperative variables were collected and analyzed by univariate statistics using chi 2 test or Student's test. Four of thirty eight patients died postoperatively in the hospital, yielding an overall mortality of 10.5%. The causes of hospital mortality were low output syndrome in 2 patients and multiple organ failure in 2 patients. By univariate analysis, male, NYHA IV class, prosthetic stenosis, hepatic failure, renal failure, and pulmonary failure were risk factors predictive of high hospital mortality. In spite of recent improvement of surgical technique and myocardial protection, the hospital mortality of patients with NYHA IV class and advanced organ failure still remains unacceptable. Therefore, it is essential to perform reoperation for primary tissue failure of bioprosthesis before severe myocardial decompensation occurs. To accomplish this goal, patients with bioprosthesis who survived beyond the certain time should be followed periodically using echocardiogram.