Relationship between renin activity and aldosterone release in the patients with low cardiac output syndrome after open cardiac surgery.

Plasma renin activity and aldosterone concentration were measured by radioimmunoassay technique in seven patients with low cardiac output syndrome after open cardiac surgery. Plasma renin activity and aldosterone concentration markedly increased, and plasma renin activity was well correlated with plasma aldosterone concentration. Plasma renin activity and aldosterone concentration, however, had no direct correlation with plasma sodium and potassium concentration or administered doses of inotropic agent, potassium and diuretic. Sodium and potassium balance was closely correlated with plasma aldosterone concentration. In the present study, it was suggested that the secondary hyperaldosteronism following low cardiac output syndrome after open cardiac surgery was mainly induced by the increased release of renin and that it influenced on the balance of sodium and potassium metabolism under such disturbed circulatory circumstances.