Nifedipine in patients with Raynaud's syndrome--effects on radial artery blood flow.

The acute effect of nifedipine on hand blood flow of 20 patients with Raynaud's phenomenon, treated in a double-blind, crossover study, is reported. Radial artery blood flow was found to correlate with the reciprocal of the pulsatility index. This simple Doppler technique gave an instantaneous record of the effect of cooling on hand blood flow. In patients with Raynaud's phenomenon, nifedipine prevents the reduction of hand blood flow that is induced by cooling in untreated patients.