[Valve replacement by ball prosthesis. Study of risk factors].

245 patients had consecutive operations for replacement of a valve by a ball-valve prosthesis in the aortic position (114) in the mitral position (91), or in more than one position (40) between 1970 and March 1973. The operative mortality was 14.3% (9.5% if emergency operations are excluded). A statistical study of the risk factors has shown the relatively minor influence of the patients' preoperative status (age, NYHA functional classification, cardiomegaly, mean pulmonary arterial pressure, mean capillary pressure) and of the conditions during surgery (duration of extacorporeal circulation, size of the prosthesis). The majority of the early deaths (19 deaths out of 35) occur as part of a syndrome of low cardiac output (9) and/or of a severe disorder of ventricular rhythm (11). 9 of the 14 post-mortem examinations on such patients showed a haemorrhagic subendocardial lesion and/or, in 4, an intracardiac thrombosis on the prosthesis. The coronary arteries were normal (14), or slightly atheromatous (1). The histological picture is one of a haemorrhagic interstitial infiltration mainly in the subendocardial layers. The late failures (secondary deaths and poor results) are essentially related with poor preoperative status (age, functional classification, cardiothoracic ratio) or with complications which would be treatable given proper and regular follow-up supervision of the patients (porsthesis which pulls away or fails to function, thromboembolic accident, coronary complication).