Exploring the Acute Influence of Blood Pressure Change on Arm Arterial Stiffness

Abstract

Arterial stiffness is a clinically relevant measure of cardiovascular health, that can be manipulated via acutely altered blood pressure (BP). How fast a pressure wave moves through an artery (pulse wave velocity (PWV)) is commonly used to assess arterial stiffness (faster=stiffer). Acutely elevated BP induced using maneuvers that change whole body blood pressure by increasing sympathetic nervous activity to the heart and blood vessels (sympathoexcitation) results in acute increases in arterial stiffness. Since these maneuvers operate systemically, it remains unclear how acute changes in pressure will impact arterial stiffness when only local factors are involved (residual capacity to stretch, myogenic responses and the venoarteriolar reflex). No study to date has explored whether acutely altering BP without sympathoexcitation, alters limb arterial stiffness, nor considered sex differences in this response. It is hypothesized that acutely elevating BP by moving the arm from above to below heart level will increase arterial stiffness through local mechanisms, with males experiencing greater increases in stiffness. Twenty healthy, young adults (10 males 21  1 years; 10 females 21  3 years [mean  SD]) participated in one laboratory visit where their forearms were manipulated into above (low forearm BP) and below (high forearm BP) heart level positions, creating local BP alteration without a stimulus for systemic sympathoexcitation. Forearm PWV and radial artery diameter were assessed in each position. Female participants were tested during the low estrogen phase of the menstrual or oral contraceptive pill cycle. As hypothesized, arterial stiffness was higher at a higher BP (p<0.001), however there was no effect of sex (p = 0.344). Artery diameter was lower at a higher BP (p = 0.015), consistent with local contraction of vascular smooth muscle. These results suggest that acutely elevating forearm BP increased forearm arterial stiffness through local vasoregulatory mechanisms, with no apparent sex differences.