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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2009;29:606.)
© 2009 American Heart Association, Inc.

Clinical and Population Studies

The Brachial Artery Remodels to Maintain Local Shear Stress Despite the Presence of Cardiovascular Risk Factors

William B. Chung; Naomi M. Hamburg; Monika Holbrook; Sherene M. Shenouda; Mustali M. Dohadwala; Dellara F. Terry; Noyan Gokce; Joseph A. Vita

From the Evans Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Mass.

Correspondence to Joseph A. Vita, MD, Section of Cardiology, Boston Medical Center, 88 East Newton Street, Boston, MA, 02118. E-mail jvita{at}bu.edu

Objective— Under physiological conditions, arteries remodel in response to changes in blood flow to maintain local shear stress. Risk factors and developing atherosclerosis may be associated with maladaptive remodeling that produces relatively large arteries with low levels of shear stress. Recent studies have shown that the brachial artery and other peripheral arteries are enlarged in patients with risk factors and cardiovascular disease, and we tested the hypothesis that this finding represents maladaptive remodeling.

Methods and Results— We measured brachial artery diameter and flow by ultrasound and calculated shear stress in a diverse cohort of 1583 subjects (age 53±17 years, 62% male, and 51% with coronary artery disease and/or peripheral arterial disease). In a stepwise linear regression model, age (P<0.001), gender (P<0.001), body mass index (P<0.001), hypertension (P=0.005), and hypercholesterolemia (P=0.02) were associated with larger brachial diameter. Older age was associated with lower shear stress (P<0.01), consistent with maladaptive remodeling. However, body mass index, hypertension, hypercholesterolemia, and prevalent atherosclerosis were associated with proportionate changes in blood flow and no difference in shear stress compared to reference groups, suggesting adaptive remodeling.

Conclusions— These findings suggest that enlargement of the brachial artery in the setting of obesity, hypertension, hypercholesterolemia, and atherosclerosis reflects adaptive remodeling. The results provide further support for the concept that arterial remodeling is an important homeostatic response that is maintained despite the presence of risk factors and developing atherosclerosis.

We investigated whether risk factors induce maladaptive remodeling in the brachial artery by measuring diameter and flow by ultrasound in 1583 subjects. Diameter and flow were higher, but shear stress was unaffected by risk factors. These findings suggest that enlargement of the brachial artery in the setting of risk factors reflects adaptive remodeling.

Key Words: remodeling • risk factors • atherosclerosis • shear stress • brachial artery