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Arterial compliance by cuff sphygmomanometer. Application to hypertension and early changes in subjects at genetic
T J Brinton1, M T Kailasam, R A Wu
1Department of Medicine, University of California-San Diego 92161, USA.
Insights
Abnormal arterial compliance, a marker of cardiovascular changes, can be detected noninvasively even before hypertension develops. These early vascular changes in individuals with genetic risk are reversible with treatment.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Vascular Biology
Background:
- Arterial pulse waveform abnormalities indicate cardiovascular changes, potentially preceding hypertension.
- Traditional methods for assessing arterial pulse waves are invasive.
- Noninvasive methods are needed to evaluate early cardiovascular changes.
Purpose of the Study:
- To evaluate arterial structure and function using a noninvasive cuff sphygmomanometer.
- To assess vascular compliance and peripheral resistance in hypertensive and normotensive subjects.
- To investigate the role of genetic risk for hypertension in early vascular changes.
Main Methods:
- Utilized a noninvasive cuff sphygmomanometer to analyze brachial artery pulsation signals.
- Employed a physical model of the aorta and brachial artery to determine vascular compliance and peripheral resistance.
- Stratified subjects (n=51) by hypertension status and genetic risk (family history).
Main Results:
- Essential hypertensive subjects exhibited significantly lower vascular compliance (P=.001) and tended towards higher peripheral resistance (P=.06).
- Normotensive individuals with a family history of hypertension showed lower vascular compliance (P=.04) and higher peripheral resistance (P=.07) compared to those without.
- Genetic risk for hypertension was a more significant determinant of vascular compliance (F=7.84, P=.007) than blood pressure status (F=2.69, P=.089).
Conclusions:
- Noninvasive detection of arterial vascular compliance abnormalities reflects treatment-reversible changes.
- Early vascular compliance changes in normotensive individuals at genetic risk may be a heritable feature of hypertension.
- Antihypertensive therapies, including ACE inhibitors and calcium channel blockers, improved vascular compliance and reduced peripheral resistance.
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.