超音波ドプラ血流検査法による妊娠中・分娩時の脳循環の測定

抄録

Cerebral circulation in pregnant women was assessed by internal carotid (ICA) and middle cerebral artery (MCA) velocimetry with transcranial Doppler (TCD) . In normal pregnant women, mean velocity of MCA at 12-15 weeks gestation became faster by 12.3% than that in nonpregnant women. After that, the velocity decreased gradually to the term. At 36-40 weeks gestation, it was 16.4% slower than that in nonpregnant women. The results from serial study were concomitant with cross-sectional study. The MCA velocity was proved to be better correlated to regional cerebral blood flow in single photon emission CT and ₁₃₃Xe inhalation study than ICA velocity. Although the causes of the change in pregnancy are far from clear, hypocapnea, metabolic acidosis, increment in cardiac output and sex steroids effects appear to affect cerebral hemodynamics. Postural change from left lateral position to supine one in late pregnant women affected cerebral circulation. We confirmed this using ICA velocimetry, that was, ICA velocity in the patients with supine hypotensive syndrome became slower than the control group. Increased incidence of cerebrovascular injuries has been noted in pregnancy. Hemorrhagic diseases such as subarachnoid hemorrhage from arteriovenous malformation are more often seen in 15-20 weeks gestation while ischemic and occlusive complications such as cerebral infarction tend to occur in the third trimester. Interestingly enough, our results were coincident with these facts, and may provide pathophysiological basis of management of pregnant patients with cerebrovascular complications.