Reduced flow velocity in the internal carotid artery independently of cardiac hemodynamics in patients with cerebral ischemia

PURPOSE: To retrospectively investigate the relationships between carotid flow velocities, clinical features and cardiac hemodynamics to assess the meaning and significance of reduced carotid flow velocities in patients with cerebral ischemic symptoms. METHODS: We selected the files from patients who had undergone duplex Doppler sonographic examination of extracranial carotid arteries, echocardiography, and MR angiography, and in whom the following parameters were available: peak systolic (PSV) and end diastolic (EDV) flow velocity, pulsatility index (PI), and diameter of the left and right common (CCA) and internal (ICA) carotid arteries, intima-media thickness (IMT) of the left and right CCA, left ventricle (LV) mass, peak flow velocity on LV outflow tract, and fractional shortening (FS). Patients with stenosis of the carotid artery or its main intracranial branches were excluded, as were patients with major cerebral infarction, severe intracranial abnormality, or heart function disorder. The remaining 59 patients were subdivided according to the presence or absence of cerebral ischemic symptoms, diabetes mellitus, arterial hypertension, and hyperlipidemia for multivariate analyses and stepwise regressions. RESULTS: Women had smaller diameters and lower PI in the left and right CCA, and smaller LV mass than men. Age, CCA diameter, and IMT showed an inverse correlation with carotid flow velocities in several arterial segments. There was a positive correlation between PSV in the left CCA and ICA and FS, and between PSV in the left CCA and peak velocity on LV outflow tract. Flow velocities in the left and right ICA were significantly slower in patients with than in patients without cerebral ischemic symptoms. CONCLUSIONS: Cardiac hemodynamics and carotid flow velocities are significantly related, only on the left side, probably due to larger hemodynamic stress. Increased intracerebral circulatory resistance is probably involved in the decrease in carotid flow velocity and increase in PI in patients with cerebral ischemic symptoms.