Carotid hemodynamic alterations in hypertensive patients with insulin resistance

BACKGROUND: Insulin resistance (IR) is implicated in the pathogenesis of atherosclerosis. One mechanism is thought to be the impaired vasodilation, which can lead to a reduction in peripheral blood flow. Hypertensive patients with IR have greater intima-media thickness (IMT) in the common carotid artery (CCA) than those without IR. However, the relationship between IR and hemodynamic alterations of the CCA has not been clarified. METHODS: Seventy patients with essential hypertension (EHT) and 11 normotensive controls (NT) participated in this study. The IMT, number of plaques, and internal dimensions of the CCA were evaluated by ultrasound imaging. Mean diastolic (Vd) and systolic (Vs) velocity were determined by the Doppler flow method, and other parameters such as Vd/Vs and the cross-sectional distensibility coefficient (CSDC) were further calculated. When the homeostasis model assessment (HOMA) index exceeded 2.0, the subject was considered to have IR. RESULTS: The IMT was positively correlated with the HOMA index in all subjects. The Vd/Vs and CSDC were significantly decreased in EHT patients with IR compared to NT and EHT patients without IR. The Vd/Vs and CSDC were negatively correlated with the HOMA index. A stepwise regression analysis revealed that age, HDL-cholesterol, and the HOMA index were independently associated with IMT in patients with EHT. Age, the HOMA index, and mean blood pressure (MBP) were independently associated with CSDC, and the first two factors were independently associated with Vd/Vs. CONCLUSIONS: Decreased distensibility of the arterial wall and ensuing low diastolic perfusion are possible mechanisms of atherosclerotic changes in the CCA in EHT patients with IR.