Accentuated remodeling on the upstream side of atherosclerotic lesions

Although it has been postulated that atherosclerotic stenotic lesions canno t remodel in response to altered flow, evidence to support or refute this h ypothesis has been elusive. In vitro models have shown that accelerated end othelial shear stress occurs on the upstream side of stenoses, while turbul ent lower shear stress is seen on the downstream side. We therefore compare d vascular remodeling at paired sites 2 mm upstream and 2 mm downstream of the site of minimal lumen area in 25 atherosclerotic lesions in 23 patients using intravascular ultrasound, Remodeling was compared by 2 methods: norm alized vessel area (vessel area(lesion)/vessel area(reference)) and remodel ing index (change in vessel area/change in plaque area from reference), Nor malized vessel area was significandy greater upstream than downstream (1.21 +/- 0.06 vs 1.12 +/- 0.09; p <0.05), despite similar plaque burden (8.84 /- 0.81 vs 8.42 +/- 0.85 mm(2)) resulting in larger lumen area (8.15 +/- 1. 02 vs 6.10 +/- 0.88 mm(2); p <0.05), Remodeling index was also significantl y higher upstream than downstream (0.67 +/- 0.20 vs 0.12 +/- 0.24, respecti vely, p <0.05), Accentuation of remodeling on the upstream side was signifi cantly correlated (r = 0.54, p = 0.01) with the mean degree of shear accele ration expected by stenosis severity. Impaired remodeling on the downstream side may partly explain stenosis propagation down a vessel. (C)2000 by Exc erpta Medica, Inc.