Plasma renin activity (PRA), angiotensin II (A II) and plasma aldosterone level were investigated in adult patients who underwent open heart surgery. RAA system showed close relation with the occurrence of low output syndrome. In order to block the vicious cycle between RAA system and diturbance of hemodynamic condition, we used angiotensin I-II converting enzyme inhibitor (captopril) in 7cases and aldosterone competitive inhibitor (potassium canrenoate) in 9 cases, in pre and post operative period.
Results; 1) After the administration of potassium canrenoate, an unusual response of RAA system was observed, but potassium balance, renal function and water balance were improved in postoperative period. 2) In pre and post operative period, an elevation of PRA, reduction of A II and aldosterone were observed after the administration of captopril. Potassium balance, renal function and water balance were superior to control group.
3) Administration of captopril in a single dose of 100mg, increasd the cardiac output, and urine excretion, decreased the systemic vascular resistence in the postoperative period. However in 2 cases blood pressure fell down to shock level, though transiently. So it will be necessary to study the optimal dose of captopril in postoperative use.
