Phentolamine infusion in cor pulmonale due to chronic obstructive pulmonary disease.

Continuous phentolamine infusion, produced a marked decrease in pulmonary arterial pressure and pulmonary vascular resistance with an increase in cardiac output, in the majority of a group of 13 patients with chronic obstructive pulmonary disease and cor pulmonale. Changes in vital capacity, forced expiratory volume in one second, arterial blood gas values and peripheral blood pressure were not significant except in one patient. The changes in the pulmonary circulation are probably due to the alpha blocking effect of phentolamine, although a direct effect of the drug on vascular smooth muscle can not be excluded.