Effects of nifedipine on forearm vascular resistance and venous capacitance in normal subjects and in patients with congestive heart failure.

The effects of oral nifedipine on limb hemodynamics were studied in 7 normal subjects, 8 patients with congestive heart failure and 2 patients who underwent sympathectomy of unilateral limb. Forearm venous capacitance remained unchanged both in normal subjects and in patients with congestive heart failure. In normal subjects, systemic vascular resistance decreased without change in forearm vascular resistance. On the other hand, both systemic and forearm vascular resistance decreased simultaneously in patients with congestive heart failure. In 2 patients with normal left ventricular function undergoing sympathectomy, limb vascular resistance decreased in the denervated side and increased in the contralateral innervated side. These findings indicate that the effects of nifedipine on forearm vascular resistance are dependent upon the circulatory state of the patient at the time the drug is administered, while venous dynamics were not changed by nifedipine, and that the difference in the density of sympathetic innervation results in a reordering of territorial blood flow by modifying the vasodilatation due to the calcium antagonistic action of nifedipine.