Background: Pulse pressure and aortic pulse wave velocity, measures of arterial stiffness, are both important determinants of cardiovascular risk. However, assessment of peripheral pulse pressure does not always provide a reliable measure of changes in central pulse pressure or arterial stiffness. The aim of the present study was to assess the effect of acute changes in heart rate on arterial stiffness and on peripheral and central pulse pressure in healthy subjects. Methods: Twenty subjects (age range, 20 to 72 years) were studied at cardiac catheterization. Pulse wave analysis was used to determine central pressure, augmentation index (AIx), a measure of systemic arterial stiffness, and aortic pulse wave velocity (PWV) during right atrial pacing (80 to 120 beats/min).

Abstract-Pulse pressure rather than diastolic pressure is the best predictor of coronary heart disease risk in older subjects, but the converse is true in younger subjects. We hypothesized that this disparity results from an age-related difference in pressure amplification from the aorta to brachial artery. Data from 212 subjects age Ͻ50 years and 230 subjects age Ն50 years were abstracted from a community database. All subjects were free from cardiovascular disease, diabetes, and medication. Peripheral blood pressure was assessed by sphygmomanometry. Radial artery waveforms recorded noninvasively by applanation tonometry were used to derive central blood pressure. Pressure amplification (peripheral/central pulse pressure ratio) was linearly related to age (rϭ0.7; PϽ0.001). There was an inverse, linear relationship between amplification and diastolic pressure in the younger group (rϭ0.3; PϽ0.001) but not in older subjects (rϭ0.1; Pϭ0.2). There was no relationship in either group when the amplification ratio was calculated with nonaugmented central pressure. Amplification is reduced in older subjects because of enhanced wave reflection. In younger, but not older, subjects, amplification declines as diastolic pressure rises. Therefore, peripheral pulse pressure underestimates the effect that diastolic pressure has on central pulse pressure in younger subjects. This may explain why diastolic pressure is a better predictor of risk in this age group and suggests that assessment of central pressure may improve risk stratification further. Key Words: blood pressure Ⅲ arteries Ⅲ pulse wave analysis T he importance of blood pressure as a determinant of cardiovascular risk and the benefits of treating hypertension have been firmly established. However, the precise component of blood pressure that best predicts risk has been the subject of considerable recent debate. 1 Data from the Framingham Study, in particular, have challenged the preeminence of diastolic blood pressure and focused attention toward pulse pressure as the best measure of cardiovascular risk, at least in older subjects. 2,3 The importance of pulse pressure is further supported by several other observational and interventional studies. 4 -7 Since pulse pressure is a surrogate measure of arterial stiffness, such data indicate that arterial stiffness is a key determinant of cardiovascular risk in older subjects. Indeed, aortic pulse wave velocity, a more robust measure of large-artery stiffness, is an independent predictor of cardiovascular risk. 8,9 Paradoxically, the latest data from Framingham suggest that diastolic pressure remains the best predictor of coronary heart disease (CHD) risk in younger subjects. 10 Although diastolic and mean arterial pressure are relatively constant throughout the arterial tree, the systolic component and, therefore, pulse pressure vary considerably. 11-13 This is due, in part, to variation in vessel stiffness and the phenomenon of wave reflection. 14,15 Normally, there is considerable amplification of pulse pressure betwee...