THE WALL TO LUMEN RATIO OF THE RADIAL ARTERY IN PATIENTS WITH RAYNAUDS-PHENOMENON

The pathophysiology of Raynaud's phenomenon (RP) remains an enigma. Wh atever theories proposed, the final event leading to the clinical symp toms is the occlusion of digital vessels. However, the possibility tha t the upstream large arterial vessels contribute to vasopasm has never been investigated. We used a high resolution echo-tracking device to calculate lumen diameter, wall thickness, and circumferential wall str ess upstream the digital arteries, i.e. at the site of the radial arte ry. Fifteen control women, 15 age-matched women with primary RP (PRP) and 15 women presenting with a secondary RP due to systemic sclerosis (SSc) were included in the study. All vasodilating agents were discont inued 72 h before the study session, which was conducted in a room wit h a stable ambient temperature of 22 degrees C. Radial artery internal diameter, intima-media wall thickness, and mean arterial pressure wer e measured simultaneously. Internal diameter of patients with RP was s ignificantly decreased (p < 0.001 vs. controls) whereas intima-media w all thickness and mean arterial pressure were closely similar in the t hree groups, resulting in an increase in the wall to lumen ratio. Thus , circumferential wall stress was significantly smaller (p < 0.05 vs. controls) in patients with RP. In conclusion, this study demonstrates that in patients with RP, wall to lumen ratio is increased and circumf erential wall stress is reduced at the level of the radial artery. It is suggested that the geometrical and mechanical changes of this arter y may favor the downstream occlusive phenomena observed in patients wi th PRP and SSc.