Abstract: Objectives: During visual stimulation, the elevated metabolism rate will couple with increase of blood flow velocity (BFV) in posterior cerebral artery (PCA). This study with TCD was aimed to investigate whether the coupling might change according to the different vasoneuronal conditions. Methods: Ninety-nine volunteers including 24 hypertension (HT) patients and 2 patients suffering from both HT and diabetes mellitus (DM) were enrolled in this trial. BFV and pulse indexes (PI) in P2 segments of PCA on both sides were monitored during visual stimulation. Results: In all subjects, Mean BFV increased and PI went down in response to visual stimulation. The percentages of changes (ΔV and ΔP) of both mean BFV and PI were larger in young group (<55 years old) than in old one (≥55 years old). There was significant positive correlation between ΔV and ΔP. Multivariated regression analysis did not show HT and DM, but age related to ΔV(ΔP). We did not find significant difference of ΔV(ΔP) between left and right sides. Conclusions: Blood flow velocity in PCA P2 segment increased due to decreased cerebrovascular resistance during visual stimulation and the response weakened with aging of the patient.

Key words: Cerebral blood flow, Ultrasonography, Vasomotor reactivity, TCD (Transcranial Doppler)

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