Acute cerebral revascularization: Part 3. Cerebral blood flow.

The efficacy of cerebral revascularization by a superficial temporal-middle cerebral artery anastomosis done 4 and 24 hours following combined occlusion of the middle cerebral and internal carotid arteries (MCA/ICA) was tested in 15 dogs. An untreated and a sham-operated group of 8 and 5 dogs, respectively, controlled possible intercurrent variables. Regional cerebral blood flow (rCBF) was measured by the hydrogen clearance method. Values of normal and preocclusion blood flow under basal conditions and following inhalation of 5% CO2 were similar to values reported by other researchers. Combined MCA/ICA occlusion produced a significant drop in rCBF in the ipsilateral hemisphere (p less than 0.01). The rCBF returned to normal following revascularization in 4 and 24 hours, and after the sham procedure. The rCBF response to inhalation of 5% CO2 was normal in the revascularized group, but was reversed (p less than 0.01) in the sham group. The reversal of flow in the sham group suggested that loss of cerebral autoregulation and steal of blood flow in the infarcted area occurred.