Abstract TP410: Microcirculatory Impairment is Caused by Independent Mechanisms From Major Arterial Spasm Both in the Acute and Chronic Phase After Experimental SAH

Abstract

Background & Objectives: The mechanism of microcirculatory disturbance following subarachnoid hemorrhage (SAH) remains to be elucidated. In this study, we investigated the correlation between the cerebral microcirculatory change and the time-dependent alteration of major arterial vasoconstriction after SAH using rabbit SAH model. Methods: CT angiography and perfusion were repeated at 0, 1, 6, 24, 48 hours after first hemorrhage for acute changes observation group (n=8), and on days 0, 3, 5, 7 for chronic changes observation group (n=8) using multi-detector raw CT. Regional cerebral blood flow (rCBF), cerebral blood volume (CBV), mean transit time (MTT) and basilar artery (BA) diameter were calculated at each time point. Results: In acute group, immediately after hemorrhage, BA narrowed, both CBV and rCBF were decreased and MTT was increased, transiently. After 6 hours, BA narrowed again and both CBV and rCBF were increased progressively. MTT restored over 24 hours. In chronic group, BA narrowing reached a peak on day 5 and restored after day 7. Both CBV and rCBF were persistently decreased after day 3, while MTT was increased after day 5. In both groups, no significant changes were observed in CBV, rCBF and MTT between in BA territory and other territory. Conclusions: Delayed cerebral ischemia may be caused by the microcirculatory disturbance which is regulated by independent mechanisms from major arterial vasospasm both in the acute and chronic phase after SAH in rabbit model.