Assessment of macro and microvascular function in aging males.

Aging is associated with reductions in endothelial function, observations primarily reported using brachial artery ultrasound. There is growing interest in the use of peripheral artery tonometry (PAT) of microvessels in the fingertip to assess endothelial function because it is less technically demanding and has a high sensitivity and specificity for assessing coronary endothelial function. Moreover, similar to brachial artery flow mediated dilation (FMD), PAT predicts cardiovascular disease (CVD) outcomes. However, the relation between PAT and FMD have yet to be examined in the context of aging. To address this question, reactive hyperemic index (RHI) using EndoPAT and flow-mediated dilation (FMD) using brachial artery ultrasound were assessed after five minutes of forearm ischemia in twenty younger (18-40 years old; 29±4 years) and twenty older (60-75 years old; 65±4 years) healthy adult men. Higher values of both FMD and RHI indicate better endothelial function. Endothelial function assessed via brachial artery FMD was lower in older (4.8±2.1%), compared to younger (7.5±1.6%) men (p<0.001). In contrast, the RHI assessed via PAT was greater in older (2.2±0.6), compared to younger (1.8±0.5) men (p=0.014). FMD and RHI were not correlated (r=-0.15; p=0.35). We conclude that PAT may not be an appropriate measure to evaluate age-associated changes in endothelial function.