The effects of hydralazine on exercise capacity in pulmonary hypertension secondary to chronic obstructive pulmonary disease.

Vasodilator therapy of pulmonary hypertension has been shown to improve hemodynamics in some patients, but the clinical benefits of this therapy have not been evaluated. We studied 14 patients who had pulmonary hypertension secondary to chronic obstructive pulmonary disease to determine the effect of hydralazine treatment on hemodynamics and maximal exercise. Baseline exercise in these subjects showed an abnormal pattern of excessive tachycardia and low stroke volumes, and the stroke volume correlated inversely with the pulmonary vascular resistance during exercise (r = -0.61, p less than 0.05). After 48 h of hydralazine there were decreases in the mean pulmonary artery pressure (43 +/- 8 to 38 +/- 8 mmHg, p less than 0.06) and pulmonary vascular resistance (3.97 +/- 0.97 to 2.88 +/- 1.28 units, p less than 0.05) measured at maximal exercise, and the maximal cardiac output was increased (8.05 +/- 2.57 to 10.13 +/- 2.79 L/min, p less than 0.05), but there was no change in symptom-limited maximal oxygen consumption (747 +/- 266 to 752 +/- 244 ml/min, p = NS). Significant increases in resting and maximal exercise values of minute ventilation and mixed venous oxygen tension were also noted with hydralazine. Repeat exercise testing after 2 to 4 months of chronic hydralazine therapy demonstrated no change in symptom-limited maximal oxygen consumption. We conclude that vasodilator therapy with hydralazine, although hemodynamically efficacious, does not increase exercise capacity in patients with severe chronic obstructive pulmonary disease and secondary pulmonary hypertension.