REMODELING OF THE RADIAL ARTERY IN RESPONSE TO A CHRONIC INCREASE IN SHEAR-STRESS

Chronic changes in large artery blood flow rates induce corresponding adjustments in arterial diameter, but little is known about structural adaptations of the vessel wall in humans. We used a high-resolution e cho-tracking system to measure radial artery internal diameter, wall t hickness, and mean blood flow on both arms of 11 patients with end-sta ge renal disease. Measurements were performed on the wrist side of the arteriovenous fistula. The contralateral radial artery was investigat ed as control. Wall cross-sectional area, circumferential wall stress, and mean wall shear stress were calculated. Results indicate a sixfol d increase in blood flow on the side of the arteriovenous fistula comp ared with the control side, with a 1.4-fold increase in internal diame ter. The diameter enlargement was sufficient to normalize wall shear s tress. Changes in diameter were not associated with arterial wall hype rtrophy because wall cross-sectional area was not increased and rather suggest a ''remodeling'' of the arterial wall. For the same level of blood pressure, circumferential wall stress was increased on the side of the arteriovenous fistula. These results suggest that the structura l adaptations of the arterial wall to a chronic increase in blood flow normalize wall shear stress and overcome stretch-induced changes in t he particular circumstance of arteriovenous fistula.