This is the first report of cerebral blood flow measurement with transcranial Doppler (TCD) during aortic arch reconstruction using continuous retrograde cerebral perfusion (CRCP) with deep hypothermia. Cerebral blood flow velocity was measured in 6 patients. CRCP was performed via the superior vena cava (SVC) at 30 cmH2O of internal juglar vein pressure and at 18 degrees C or lower of minimum bladder temperature. During the operation, the flow velocity of the middle cerebral artery (MCA) was continuously measured with TCD fixed on the temple. The cerebral blood flow during CRCP was different in each of the 6 patient. The retrograde MCA flow could be measured during CRCP in 3 patients, and the flow velocity was 11-60% of the MCA flow velocity before cardiopulmonary bypass. In the other 3 patients, retrograde MCA flow could not be detected during CRCP, but antegrade MCA flow could be found after antegrade perfusion was resumed. The antegrade flow velocity right after CRCP became more than the MCA flow before CRCP, which was regarded as a reaction due to cerebral ischemia. All the patients awoke within several (2-9) hours after operations and had no permanent neurological complications. But 2 patients developed drowsiness for several days after the operations; their CRCP times were 127 and 131 minutes. It is concluded that CRCP is a simple technique for brain protection, but the cerebral blood flow during CRCP is a simple technique for brain protection, but the cerebral blood flow during CRCP is different in each patient.(ABSTRACT TRUNCATED AT 250 WORDS)