Elevated serum levels of S-100 after deep hypothermic arrest correlate with duration of circulatory arrest.

OBJECTIVE: Cerebral damage is a major problem after reconstructive surgery of the aortic arch and the descending aorta. Current protective strategies, including deep hypothermia and retrograde cerebral perfusion, are used to prolong the tolerated duration of circulatory arrest, and the latter may also decrease the possibility of air/particle embolization. The aim of the current study was to investigate whether the neurochemical marker S-100 is related to the duration of circulatory arrest, when the influence of embolic injury has been minimized by the use of retrograde cerebral perfusion during the last part of circulatory arrest.
METHODS: Arterial serum levels of S-100 were followed before, during and after reconstructive surgery of the thoracic aorta during deep hypothermic arrest in ten adults. Retrograde cerebral blood perfusion was used during the latter part of the arrest period in eight of the ten patients. Neurologic status 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 cerebral perfusion was 50 (3-118) min and 16 (0-84) min, respectively. S-100 increased 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). The duration 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 first postoperative day (r(S) = 0.83, P<0.01). However, there was no significant correlation between duration of arrest and duration of CPB. The duration of circulatory arrest without retrograde cerebral perfusion correlated 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 arrest correlate with the duration of circulatory arrest, indicating that the duration of circulatory arrest is damaging to the brain despite the use of deep hypothermia and partial retrograde cerebral perfusion. The highest correlation between S-100 and duration of arrest was seen on the first postoperative day. S-100 appears to perform well under clinical circumstances as a sensitive and discriminative marker for neuronal injury.