抄録
The present study was performed to examine the influence of head-up postural change on cerebral circulation in patients with internal carotid artery occlusion (ICAO) . Duplex ultrasonography was used to measure blood flow velocity (FV) and pulsatility index (PI) of the common carotid artery (CCA) in 11 men with unilateral ICAO (aged 63.0±7.2 yr) while they were lying flat, as well as standing up. In addition, the change in cerebral blood flow (CBF) after becoming upright was evaluated using SPECT. No patient showed any sign of orthostatic hypotension. FVs and PI on the nonoccluded side and systolic FV on the occluded side remained unchanged, while mean, end-diastolic (ED) FVs on the occluded side decreased, and the PI on the occluded side increased. Thus, the side-to-side ratio of EDFV (ED ratio) increased in all cases. A decrease in CBF was observed in 7 out of 9 patients when they were standing upright. The degree of the increase in the ED ratio was associated with worsening of hypoperfusion in upright SPECT. Our results suggest that head-up postural change increases the relative resistance of the CCA against the decrease in carotid arterial pressure due to gravity in carotid occlusive disease, and that cerebral dysautoregulation might then occur. Duplex ultrasonography and SPECT are both safe and useful methods for evaluating the hemodynamic influence of head-up postural change on cerebral circulation in such patients, and the upright test is helpful in diagnosing ICAO using Doppler sonography because of the conspicuous laterality of the FVs.
