[Treatment of low cardiac output following extracorporeal circulation with captopril]

Seven patients in low-output cardiac failure, resistant to conventional vasodilators and inotropic agents, following surgery with extra-corporeal circulation were given oral captopril, an angiotensin converting enzyme inhibitor. The effects of captopril on haemodynamic and renal function were studied after 2, 6, 12 and 24 hours of treatment. After two hours, there was a mean reduction in systemic arterial resistance of 29%, in pulmonary arterial resistance of 18% and in pulmonary wedge pressure of 15%. The mean increase in the cardiac index was 28%. This marked initial haemodynamic improvement was either maintained or increased over the rest of the 24 hours. By 24 hours there had been a mean increase in urinary sodium excretion of 200%. The urinary sodium/potassium ratio increased from 0.62 to 1.45. Oral captopril thus seems suitable for treating low-output cardiac failure following surgery requiring extra-corporeal circulation.