Melvyn Rubenfire1, Ning Cao, Dean E Smith, Lori Mosca. 1. Division of Cardiology, Department of Internal Medicine, University of Michigan Health System, P.O. Box 363, 24 Frank Lloyd Wright Drive, Ann Arbor, MI 48106-0363, USA. mrubenfi@umich.edu
Abstract
BACKGROUND: The change in brachial artery diameter (DBA(d)) following release of an occluding cuff (BAO(cclR)) has been used to characterize local endothelial function and coronary risk. We designed a study to determine the CA diameter (CA(d)) response to exercise (IHG), whether the response is influenced by coronary risk, and compare it with the BAO(cclR) method. METHOD AND RESULTS: High resolution ultrasound was used to detect the DCA(d) in response to120 s of 33% of maximum and DBA(d) was measured 60 s following release of an occluding cuff. There was no change in CA(d) during IHG. At 90 s following release, CA(d) dilated >0.1 mm in 95% of volunteers with average risk (mean 0.42+/-0.25 mm or 5.97+/-3.5%). There was no change or constriction in 62% of high risk (0.01+/-0.28 mm, 0.0+/-3.6%), and predominantly constriction in CAD subjects (-0.22+/-0.23 mm, -0.01+/-3.2%), P=0.0001 for trend and 0.01 between groups. The %DCA(d) following IHG and %DBA(d) following OcclR were highly correlated, r=0.66, P=0.0001. The major determinant of response to each stressor was group (%DBA(d) R(2)=0.55 and %DCA(d) R(2)=0.52). CONCLUSIONS: The reactivity of the carotid artery to IHG is highly influenced by coronary risk, and may be an additional modality to characterize pre-clinical CAD and assess treatment strategies.
BACKGROUND: The change in brachial artery diameter (DBA(d)) following release of an occluding cuff (BAO(cclR)) has been used to characterize local endothelial function and coronary risk. We designed a study to determine the CA diameter (CA(d)) response to exercise (IHG), whether the response is influenced by coronary risk, and compare it with the BAO(cclR) method. METHOD AND RESULTS: High resolution ultrasound was used to detect the DCA(d) in response to120 s of 33% of maximum and DBA(d) was measured 60 s following release of an occluding cuff. There was no change in CA(d) during IHG. At 90 s following release, CA(d) dilated >0.1 mm in 95% of volunteers with average risk (mean 0.42+/-0.25 mm or 5.97+/-3.5%). There was no change or constriction in 62% of high risk (0.01+/-0.28 mm, 0.0+/-3.6%), and predominantly constriction in CAD subjects (-0.22+/-0.23 mm, -0.01+/-3.2%), P=0.0001 for trend and 0.01 between groups. The %DCA(d) following IHG and %DBA(d) following OcclR were highly correlated, r=0.66, P=0.0001. The major determinant of response to each stressor was group (%DBA(d) R(2)=0.55 and %DCA(d) R(2)=0.52). CONCLUSIONS: The reactivity of the carotid artery to IHG is highly influenced by coronary risk, and may be an additional modality to characterize pre-clinical CAD and assess treatment strategies.