Arterial Compliance by Cuff Sphygmomanometer

Abstract

Abnormalities of the arterial pulse waveform reflect changes in cardiovascular structure and function. These abnormalities may occur early in the course of essential hypertension, even before the onset of blood pressure elevation. Previous studies of cardiovascular structure and function have relied on invasive intra-arterial cannulation to obtain the arterial pulse wave. We evaluated arterial structure and function using a noninvasive cuff sphygmomanometer in hypertensive (n=15) and normotensive (n=36) subjects stratified by genetic risk (family history) for hypertension. Using a simple physical model in which the aorta was assumed to be a T tube and the brachial artery a straight tube, we determined vascular compliance and peripheral resistance by analyzing the brachial artery pulsation signal from a cuff sphygmomanometer. Essential hypertensive subjects tended to have higher peripheral resistance ( P =.06) and significantly lower vascular compliance ( P =.001) than normotensive subjects. Vascular compliance correlated with simultaneously determined pulse pressure in both groups (n=51, r =.74, P <.0001). Higher peripheral resistance ( P =.07) and lower vascular compliance ( P =.04) were already found in still-normotensive offspring of hypertensive parents (ie, normotensive subjects with a positive family history of hypertension) than in normotensive subjects with a negative family history of hypertension. Multivariate analysis demonstrated that both genetic risk for hypertension ( P =.030) and blood pressure status ( P =.041), although not age ( P =.207), were significant predictors of vascular compliance (multiple R =.47, P =.011). However, by two-way ANOVA, genetic risk for hypertension was an even more significant determinant (F=7.84, P =.007) of compliance than blood pressure status (F=2.69, P =.089). Antihypertensive therapy with angiotensin-converting enzyme inhibitors (10 days, n=10) improved vascular compliance ( P =.02) and reduced resistance ( P =.003) significantly; treatment with calcium channel antagonists (4 weeks, n=8) tended to improve vascular compliance ( P =.07) and significantly reduced peripheral resistance ( P =.006). We conclude that arterial vascular compliance abnormalities detected by a noninvasive cuff sphygmomanometer reflect treatment-reversible changes in vascular structure and function. Early changes in vascular compliance in still-normotensive individuals at genetic risk for hypertension may be a heritable pathogenetic feature of this disorder.