| Background and purpose: To assess the cerebrovascular reserve capacity (CRC) in health subjects and patients with cerebral hemodynamic compromise by means of transcranial ultrasonography (TCD) with breath-holding maneuver, carotid color duplex and digital angiography, and to explore the association of hemodynamics and related risk factors with cerebral ischemic stroke.Methods: Using TCD and breath-holding technique, we observed BHI value, which was the percentage increase in middle cerebral artery (MCA) blood flow velocity during breath-holding in healthy and patients with risk factors of cerebrovascular disease, cerebral infarction or carotid artery stenosis as index of CRC assessment. Clinically, we analyzed the risk factors of hemodynamic stroke. We also evaluated the clinical significance of the asymmetry in both carotid common arteriy diameter indictative of variation of Willis circle.Results: BHI value was not significantly related to age in health people. Risk factors including hypertension, dyslipidemia, diabetes mellitus and smoking, especially hypertension significantly impaired CRC. BHI in cerebral infarction group was significantly decreased, compared with the control group. Among stroke subtype, BHI was markedly reduced in atherothrombotic and lacunar infarction, but had no significant difference in cardioembolic subgroup. In patients with carotid artery disease, BHI significantly impaired in the patients with a arterial stenosis more than 70%, compared with those in patients with less than 70%. Clinically, inappropriatedecrease of blood pressure can induce the hemodynamic stroke. A more than 0.7mmdifference between both CCA diameter indicates the variation of Willis.Conclusion: The breath-holding test is a simple, economic and effective method forassessing CRC. Clinically, intensive blood pressure control can help prevent ischemicstroke. The asymmetry in both carotid common arteriy diameter more than 0.7mm ispossibly indiectative of variation of Willis circle.
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