Digital vasodilatation during mental stress in patients with Raynaud's disease.

Fingertip blood flow was measured by venous occlusion plethysmography before and during a stressful mental task consisting of rapid serial arithmetic calculations in a 25 degrees C room. Significant rises in heart rate and blood pressure indicated that stress was actually induced in all individuals. During mental stress in normal subjects, blood flow decreased (46.4 +/- 6.2 to 22.4 +/- 4.9 ml X min-1 per 100 ml tissue; P less than 0.01) and vascular resistance increased (2.1 +/- 0.4 to 7.6 +/- 2.2 units; P less than 0.01). Patients with Raynaud's disease unexpectedly increased blood flow (15.4 +/- 4.2 to 21.6 +/- 5.7; P = 0.05) and decreased vascular resistance (9.7 +/- 2.3 to 7.1 +/- 1.4; P = 0.05). Ten additional normal subjects were studied in a cool room (20 degrees C). Their digits remained vasoconstricted during stress, as blood flow (7.4 +/- 2.9 to 5.1 +/- 1.3) and vascular resistance (31.5 +/- 11.1 to 34.4 +/- 8.2) varied insignificantly (P greater than 0.10). The digital vasodilatation which occurs during mental stress in patients with Raynaud's disease was not altered by pretreatment with oral indomethacin, with intra-arterial propranolol or atropine, or by digital nerve block. These findings suggest the existence of an active digital vasodilatory mechanism in patients with Raynaud's disease.