There are few data available about the hemodynamic effects of isometric handgrip in severe congestive heart failure and its role in the evaluation of vasodilatory therapy. Therefore, we studied 20 patients with dilated cardiomyopathy at rest, during isometric handgrip, and during supine bicycle exercise before and after a single 25-mg dose of captopril. During handgrip, heart rate (p less than 0.001); systemic vascular resistance (p less than 0.01); systolic, mean, and diastolic pulmonary artery pressure (p less than 0.01) increased significantly; stroke volume index fell (p less than 0.05); whereas mean arterial pressure showed only a small increase, and cardiac index did not change. In contrast, mean arterial pressure and cardiac index increased during dynamic exercise (p less than 0.001), and peripheral resistance decreased (p less than 001). During both handgrip and bicycle exercise, captopril induced a decrease of arterial pressure (p less than 0.01 and p less than 0.001; respectively), peripheral resistance (p less than 0.001 and p less than 0.01; respectively), and systolic (p less than 0.01 and p less than 0.001, respectively) mean (p less than 0.001), and diastolic pulmonary artery pressure (p less than 0.001). Captopril induced and increase in stroke volume index (p less than 0.01) and cardiac index (p less than 0.001 and p less than 0.01 respectively) during both types of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)