Effects of Hypertension on Viscoelasticity of Carotid and Femoral Arteries in Humans

Abstract

We compared the properties of common carotid and femoral arteries of 16 normotensive and 14 hypertensive men. Arterial pressure and diameter were recorded noninvasively in each vessel by tonometric and echotracking devices. The x-y composition of pressure and diameter waves provided the diameter-pressure hysteresis loop. The elastic diameter-pressure curve and wall viscosity index were deduced after hysteresis elimination. The compliance-pressure and distensibility-pressure curves were derived from the diameter-pressure curve, allowing the calculation of effective compliance and distensibility at the prevailing pressure of each subject and isobaric compliance and distensibility at the same standard pressure in all subjects. Systolic, diastolic, mean, and pulse pressures and diameters in each vessel were higher in the hypertensive than the normotensive group, except carotid pulse diameter, which did not differ. The carotid diameter-pressure, compliance-pressure, and distensibility-pressure curves did not differ between groups. In the carotid artery hypertensive patients had isobaric compliance and distensibility values similar to those of normotensive subjects, despite lower effective compliance (P < .05) and distensibility (P < .01). The femoral diameter-pressure curve was higher (P < .05) and the femoral compliance-pressure and distensibility-pressure curves were lower (P < .01) in the hypertensive than the normotensive group. Hypertensive patients had effective and isobaric femoral compliance and distensibility values lower than to those of normotensive subjects (P < .001). In both arteries, viscosity index was higher in the hypertensive than the normotensive group (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of the acute arterial effects of converting enzyme inhibition in essential hypertension: a double-blind, comparative and crossover study

“…1 Studies in untreated subjects with essential hypertension indicate that the decreased compliance observed in hypertensive subjects may be the simple consequence of the elevated BP in some arterial segments, like the common carotid artery, or may be strongly influenced by the structure of the arterial wall, as recently shown for the femoral artery. 8,9 This problem requires that, in cardiovascular clinical trials, sophisticated statistical analysis may be performed, enabling simultaneous evalu-ation of the drug effect, of the pressure effect, and finally also taking into account the large heterogeneity of the various segments of the arterial tree. Statistical analysis, enabling the discrimination between such varieties of responses, have been widely developed.…”

Progressive arterial wall stiffening in patients with increasing diastolic blood pressure

“…Thus, diastolic blood pressure seems to affect arterial wall dynamics of various arteries differently which is in accordance with the results of others. 7,14 One possible explanation for the heterogeneity between the elastic carotid and the muscular femoral artery may be the fact that elastic properties in muscular arteries can be modified by vasoactive substances (such as angiotensin, noradrenaline and atrial natriuretic factor) or the central nervous system. 10 There were small nonsignificant differences in dynamic vessel wall properties of the right compared with the left common carotid artery.…”

“…Therefore individual distensibility-pressure curves were made by others 7,23,24 to compare arterial wall dynamics at a standardised pressure. At 100 mm Hg enhanced arterial wall stiffening was only present at the femoral artery which suggests structural alterations at this site.…”

“…5,6 Results of studies which compared CC and DC of the common carotid (elastic arteries) and common femoral arteries (muscular arteries) between normotensive and hypertensive patients revealed decreased CC and DC in hypertensives. [7][8][9] The elastic properties of muscular arteries are variable in the short-term which is partly due to influences of both vasoactive substances and the central nervous system. 10 Whether CC and DC gradually decline with increasing blood pressure and whether the relationship between blood pressure and arterial wall dynamics is different at the various sites of the arterial tree (which is possibly reflected in differences in risk factor patterns of cardiovascular complications) was the subject of this study.…”

Non-invasive Monitoring of Arterial Wall Impedance

“…Barra et al measured time series of blood pressure and diameter of the brachial artery in conscious dogs, and calculated the stress-strain relations during vasoconstriction and vasodilation using a modified Maxwell model [4]. They also explained that the stiffness and viscosity of smooth muscles showed similar changes according to the degree of vascular contraction [5], [6]. Meanwhile, the authors modeled the dynamic characteristics of the human arterial wall by using mechanical impedance including stiffness, viscosity, and inertia, and developed a new technique to estimate the vascular impedance parameters in a beat-to-beat manner [7], [8].…”