Differences in hemodynamic response to vasodilation due to calcium channel antagonism with nifedipine and direct-acting agonism with hydralazine in chronic refractory congestive heart failure.

The hemodynamic response to a similar reduction of systemic vascular resistance after nifedipine and hydralazine administration was compared in a randomized crossover protocol in patients with severe chronic congestive heart failure (CHF). All 15 patients showed a 25% or greater reduction in vascular resistance with intravenous hydralazine (5 to 30 mg) and 11 patients showed a similar response with oral nifedipine (20 to 50 mg). In the latter 11 patients, despite similar reductions in systemic vascular resistance (35 +/- 2% with nifedipine and 36 +/- 4% with hydralazine, difference not significant), nifedipine resulted in a smaller increase in stroke volume index (from 23 +/- 2 to 30 +/- 2 ml/m2 and from 24 +/- 2 to 34 +/- 2 ml/m2 with hydralazine, p less than 0.05), cardiac index (from 2.0 +/- 0.1 to 2.6 +/- 0.2 liters/min/m2 with nifedipine and from 2.0 +/- 0.1 to 2.8 +/- 0.2 liters/min/m2 with hydralazine, p less than 0.05) and stroke work index (from 25 +/- 3 to 27 +/- 3 gm/m2 with nifedipine and from 26 +/- 2 to 32 +/- 2 gm/m2 with hydralazine, p less than 0.05). The decrease in blood pressure after nifedipine was slightly but not significantly larger than that with hydralazine (13 +/- 3% vs 8 +/- 2%). The changes in right atrial pressure, pulmonary artery wedge pressure and pulmonary vascular resistance were similar. The 4 patients who did not reduce their systemic vascular resistance by at least 25% with nifedipine had a worsening of their hemodynamic state as evidenced by 1 or more of the following findings: elevation of vascular resistance, decrease in cardiac index and increase in pulmonary artery wedge pressure.(ABSTRACT TRUNCATED AT 250 WORDS)