Acute hemodynamic effects of nifedipine at rest and during stress in severe aortic incompetence.

To determine whether afterload reduction with nifedipine is effective both at rest and during stress tests (rapid atrial pacing and contrast material overload), 14 patients with chronic severe isolated aortic insufficiency (10 asymptomatic) underwent right and left cardiac catheterization. Forty-five minutes after 20 mg of nifedipine (sublingually), left ventricular end-diastolic pressure, peak aortic pressure, systemic vascular resistance and double product decreased significantly at rest, at peak paced rate, and after angiography (P values from less than 0.05 to less than 0.001). Cardiac index increased at resting heart rate (P less than 0.01) but was unchanged during pacing. The reduction of systemic vascular resistances was inversely correlated with its initial value (r = -0.69). After nifedipine, average regurgitant fraction did not change; however its variations were significantly correlated with those of systemic vascular resistance (r = 0.69). It is concluded that in severe aortic insufficiency, nifedipine induces an effective reduction of left ventricular pre- and afterload, accompanied by an enhanced mechanical efficiency (unchanged or increased cardiac index with lower double product), both at rest and during stress tests.