[Valve replacement, a possible factor in myocardial deterioration].

Cardiopulmonary bypass (CPB) may be a cause of myocardial damage in a small number of patients undergoing valve replacement (4 out of 1576 valve replacements). The responsibility of CPB can only be presumed when: the degree of myocardial dysfunction after surgery can be quantified, other causes of myocardial dysfunction are excluded. the type of valvular disease is taken into consideration. Variations in load after correction of certain lesions (mitral regurgitation) makes changes of LV systolic function difficult to interpret. The first case concerned a 23 year old patient operated for aortic regurgitation (Björk prosthesis) under local and general hypothermia and followed-up for 1 year after surgery. Ventricular extrasystoles and left bundle branch block were observed during surgery and radiological and echocardiographic LV dilatation persisted with deterioration of echographic, isotopic, haemodynamic and angiographic parameters of LV function: ejection fraction fell from 62% before surgery to 35% with diffuse hypokinesia and persistent LV dilatation (191 vs 188 ml). In the absence of prosthetic valve dysfunction, associated valve lesions or coronary artery disease, LV deterioration was attributed to CPB and inadequate myocardial protection. In two other cases (60 and 62 years) correction of aortic stenosis (Starr 1260) with coronary perfusion was followed by cardiac failure with left bundle branch block, deterioration of LV function, and death after 3 years in one case and precarious survival at 10 years in the other. In a fourth case (mixed mitral valve disease corrected by a Starr prosthesis under aortic clamping), the variation of cardiac load before and after surgery made changes in LV function difficult to interpret. (ABSTRACT TRUNCATED AT 250 WORDS)