ABSTRACT
BACKGROUND: Carotid intima-media thickness (IMT) and plaque burden evaluated by B-mode ultrasound have been used as relevant indicators for carotid atherosclerosis. This study was aimed to investigate the relationship between hemodynamic parameters in the common carotid artery (CCA) and the severity of carotid atherosclerosis in untreated hypertensive patients. METHODS: Carotid IMT and plaque burden were evaluated in bilateral CCA, bifurcations, external and internal carotid arteries using duplex ultrasound in 80 untreated hypertensive patients. The patients were divided into four groups according to plaque burden. Hemodynamic parameters of CCA, including peak and mean circumferential wall tension (CWT), tensile stress (TS), wall shear stress (WSS), and Young's elastic modulus (YEM), were calculated after measurements of internal diameter (ID), IMT, and peak and mean flow velocities of CCA. Arterial stiffness was also assessed using the brachial-ankle pulse wave velocity (baPWV). RESULTS: Age, pulse pressure, creatinine, carotid IMT, and mean TS were shown to have significant differences among the four plaque groups (P < 0.05). Peak CWT and peak TS were also shown to have marginal differences. In univariate analysis, the peak and mean CWT and TS were significantly correlated with plaque score. Stepwise multiple regression analysis showed that carotid IMT, age, and peak CWT were independently associated with plaque score. CONCLUSIONS: These results suggest that the CWT and TS of the CCA are associated with the severity of carotid atherosclerosis in untreated hypertensive patients. Hence, the hemodynamics of vessels may contribute to the plaque burden of low-resistance arteries.
Subject(s)
Carotid Artery Diseases/physiopathology , Carotid Artery, Common/physiopathology , Hemodynamics , Hypertension/complications , Adult , Aged , Aged, 80 and over , Ankle/blood supply , Blood Flow Velocity , Blood Pressure , Brachial Artery/physiopathology , Carotid Artery Diseases/diagnostic imaging , Carotid Artery Diseases/etiology , Carotid Artery, Common/diagnostic imaging , Cross-Sectional Studies , Elasticity , Female , Humans , Hypertension/diagnostic imaging , Hypertension/physiopathology , Male , Middle Aged , Models, Cardiovascular , Risk Factors , Severity of Illness Index , Stress, Mechanical , Ultrasonography, Doppler, DuplexABSTRACT
BACKGROUND: The resistive index (RI) of the carotid artery is a hemodynamic parameter that depends on the degree of vascular resistance in hypertensive patients. The pulsatility index (PI) of the carotid artery was shown to be associated with microangiopathy in diabetic patients. In contrast to carotid intima-media thickness (IMT), no study has yet applied the carotid RI and PI to estimate coronary heart disease (CHD) risk. METHODS: Framingham risk scores (FRS) were determined for 62 patients (32 women; mean age 65 years (range 35-83)) with essential hypertension. Duplex sonography of the common carotid artery (CCA) was performed, with determination of RI, PI, and IMT. RESULTS: The mean FRS of all patients was 14.3% (range 1-30%), the mean IMT value of CCA was 0.89 +/- 0.23 mm, the mean RI was 0.71 +/- 0.07, and the mean PI was 1.46 +/- 0.39. FRS was found to have highly significant correlations with RI and PI (r = 0.47, P < 0.001 and r = 0.45, P < 0.001, respectively). The correlation between FRS and IMT was also significant (r = 0.41, P = 0.001). Multiple stepwise regression analysis showed that RI was an independent determinant of the risk of CHD. CONCLUSIONS: Although RI indirectly reflected the atherosclerotic process, the correlation between RI and CHD risk was comparable to the well-known correlation between cardiovascular event and carotid IMT. Hence, carotid RI can be used as a tool for risk stratification in Taiwanese patients with essential hypertension.
