OBJECTIVE: Cerebral damage is a major problem after reconstructivesurgery of the aortic arch and the descending aorta. Current protectivestrategies, including deep hypothermia and retrograde cerebral perfusion,are used to prolong the tolerated duration of circulatory arrest, and thelatter may also decrease the possibility of air/particle embolization. Theaim of the current study was to investigate whether the neurochemicalmarker S-100 is related to the duration of circulatory arrest, when theinfluence of embolic injury has been minimized by the use of retrogradecerebral perfusion during the last part of circulatory arrest. METHODS:Arterial serum levels of S-100 were followed before, during and afterreconstructive surgery of the thoracic aorta during deep hypothermic arrestin ten adults. Retrograde cerebral blood perfusion was used during thelatter part of the arrest period in eight of the ten patients. Neurologicstatus was followed daily. RESULTS: All patients survived the operation.The median (range) duration of cardiopulmonary bypass (CPB) was 184.5 (121-386) min. The median duration of circulatory arrest and retrograde cerebralperfusion was 50 (3-118) min and 16 (0-84) min, respectively. S-100increased from 0.10 (0.02-0.18) microg/l preoperatively to 2.37(0.64-10.80) microg/l after CPB (P<0.01), followed by a decrease to 0.79(0.21-2.64) microg/l on the first postoperative day (P<0.01). Theduration of circulatory arrest correlated with S-100 levels after CPB (r(S)= 0.71, P<0.05) and even better with the S-100 levels on the firstpostoperative day (r(S) = 0.83, P<0.01). However, there was nosignificant correlation between duration of arrest and duration of CPB. Theduration of circulatory arrest without retrograde cerebral perfusioncorrelated well with S-100 levels on the first postoperative day (r(S) =0.88, P<0.01), but not significantly with S-100 levels after CPB.CONCLUSIONS: S-100 levels after aortic surgery with deep hypothermic arrestcorrelate with the duration of circulatory arrest, indicating that theduration of circulatory arrest is damaging to the brain despite the use ofdeep hypothermia and partial retrograde cerebral perfusion. The highestcorrelation between S-100 and duration of arrest was seen on the firstpostoperative day. S-100 appears to perform well under clinicalcircumstances as a sensitive and discriminative marker for neuronalinjury.