Carotid wall viscosity increase is related to intima-media thickening in hypertensive patients.

Increases in arterial wall viscosity and intima-media thickness (IMT) were found in hypertensive patients. Because smooth muscle cells are responsible for the viscous behavior of the arterial wall and they are involved in the process of thickening of the intima-media complex, this study evaluates the relationship between carotid thickness and wall viscosity. The simultaneous and noninvasive assessment of the intima-media complex and arterial diameter waveform was performed using high-resolution ultrasonography. This technique was contrasted against sonomicrometry in sheep, showing that the waveforms obtained by both methods were similar. The common carotid arteries of 11 normotensive subjects (NTA) and 11 patients with mild to moderate essential hypertension (HTA) were measured noninvasively by using tonometry and an automatic densitometric analysis of B-mode images to obtain IMT and instantaneous pressure and diameter loops. A viscoelastic model was used to derive the wall viscosity index (eta) using the hysteresis loop elimination criteria. In NTA, eta was 2.73+/-1.66 (mm Hg x s/mm) and IMT was 0.58+/-0.08 (mm), whereas in HTA, eta was 5.91+/-2.34 (P<.025) and IMT was 0.70+/-0.12 (P<.025), respectively. When all data of eta versus IMT of NTA and HTA were pooled in a linear regression analysis, a correlation coefficient of r=.71 (P<.05) was obtained. Partial correlation between eta and IMT holding constant pressure was r=.59 (P<.05). In conclusion, wall viscosity increase was associated with a higher IMT even maintaining blood pressure fixed, suggesting that the intima-media thickening might be related to smooth muscle alterations manifested as an increase in viscous behavior.

[1]  A. Simon,et al.  Echographic assessment of carotid and femoral arterial structure in men with essential hypertension. Group PCVMETRA. , 1996, American journal of hypertension.

[2]  Alain Simon,et al.  Mechanical Pressure Versus Intrinsic Effects of Hypertension on Large Arteries in Humans , 1991, Hypertension.

[3]  A. Simon,et al.  Evidence for in vivo carotid and femoral wall thickening in human hypertension. Groupe de Prévention Cardio-vasculaire en Médecine du Travail. , 1993, Hypertension.

[4]  A. Simon,et al.  Carotid artery and left ventricular structural relationship in asymptomatic men at risk for cardiovascular disease. , 1996, Atherosclerosis.

[5]  R. Armentano,et al.  Arterial wall mechanics in conscious dogs. Assessment of viscous, inertial, and elastic moduli to characterize aortic wall behavior. , 1995, Circulation research.

[6]  A. Simon,et al.  Wall thickening of carotid and femoral arteries in male subjects with isolated hypercholesterolemia. PCVMETRA Group. Prevention Cardio-Vasculaire en Medecine du Travail. , 1995, Atherosclerosis.

[7]  P Pignoli,et al.  Intimal plus medial thickness of the arterial wall: a direct measurement with ultrasound imaging. , 1986, Circulation.

[8]  A. Simon,et al.  Coronary Calcification and Its Relation to Extracoronary Atherosclerosis in Asymptomatic Hypercholesterolemic Men , 1992, Circulation.

[9]  R Armentano,et al.  Effects of hypertension on viscoelasticity of carotid and femoral arteries in humans. , 1995, Hypertension.

[10]  P. Pignoli.  Ultrasound B-mode imaging for arterial wall thickness measurement , 1984 .

[11]  Rheological approaches of arteries. , 1984, Biorheology. Supplement : the official journal of the International Society of Biorheology.

[12]  R H Selzer,et al.  Evaluation of computerized edge tracking for quantifying intima-media thickness of the common carotid artery from B-mode ultrasound images. , 1994, Atherosclerosis.

[13]  J Melbin,et al.  Arterial tonometry: review and analysis. , 1983, Journal of biomechanics.

[14]  R. Armentano,et al.  Assessment of smooth muscle contribution to descending thoracic aortic elastic mechanics in conscious dogs. , 1993, Circulation research.