Relation between baroreflex sensitivity and carotid artery elasticity in healthy humans

We investigated whether physiological variability in arterial baroreflex sensitivity (BRS) was related to differences in carotid elastic behavior among 19 young healthy subjects (age 18-26 yr). The diameter of the carotid artery (D) and its change during the arterial pulse (delta D) were monitored by a phase-locked echotracking device (UT-4 Hokanson), and pulse pressure (delta P) was measured in the brachial artery by sphygmomanometry. Distensibility coefficient (DC) for the common carotid artery was calculated using the formula DC = (2 x delta D/D)/delta P. Dynamic elastic parameters such as the maximum and mean rate of carotid artery expansion and the dominant harmonic frequency of the diameter curve were also determined. BRS was assessed by regressing R-F.intervals against systolic blood pressure, monitored by finger arterial pressure (FINAPRES), during an elevation of pressure, induced by intravenous bolus injection of phenylephrine. Using correlation and stepwise regression analysis, we found that BRS was significantly related to carotid artery distensibility (r = 0.778, P < 0.001) but was not related to any of the dynamic parameters of carotid pulsation.