Effects of mental stress on brachial artery flow-mediated vasodilation in healthy normal individuals

Background Mental stress is associated with increased risk for cardiovascul ar events, possibly because of acute increases in endogenous catecholamines . Recently, brachial artery flow-mediated vasodilation has been used for no ninvasive assessment of macrovascular endothelial function. The effect of m ental stress and its associated changes in sympathetic activation on brachi al artery endothelium-dependent vasomotor tone in vivo remains unknown. Methods and Results Two-dimensional ultrasound was used to measure brachial artery flow-mediated vasodilation before and after mental stress (provoked by a standard arithmetic challenge) in 21 healthy individuals (10 men, 1 1 women; average age 23.5 years). The flow stimulus resulted from a 3-minute cuff occlusion of distal forearm blood flow, causing distal hyperemia and a transient 2- to 3-fold increase in brachial artery blood flow on cuff rel ease. During mental stress, heart rate increased on average by 29.6% and bl ood pressure increased on average by 17.9%. The sympathetic stimulus result ed in a 64% average increase in flow-mediated vasodilator response (P < .00 1). The enhanced vasodilator response during mentor stress was similar for men and women. Conclusions Mental stress can have marked effects on endothelium-dependent, flow-mediated vasodilation in healthy, normal individuals. Similar studies in individuals with impaired endothelial function may further our understa nding of the role of mental stress in the development of cardiovascular eve nts.