Comparative experimental study of cerebral protection during aortic arch reconstruction

Background. The optimal adjunctive method for cerebral protection during aortic arch repair remains controversial. Methods. Retrograde cerebral perfusion, selective cerebral perfusion, and hypothermic circulatory arrest were compared in terms of their effect on cerebral function of mongrel dogs using somatosensory evoked potentials. Brain temperatures were held at 20°C for 90 minutes during cerebral perfusion or circulatory arrest and then rewarned gradually to normal temperature. Results. Somatosensory evoked potentials completely disappared as soon as retrograde cerebral perfusion or hypothermic circulatory arrest started and did not recover completely. In the selective cerebral perfusion group, it recovered in all cases. Only 2% of cerebral blood flow and about 3% of the cerebral metabolic rate for oxygen were obtained during retrograde cerebral perfusion compared with the preoperative value. The analysis of adenosine triphosphate and water content of the brain supported these results. Conclusions. Retrograde cerebral perfusion had some advantage for cerebral protection compared with hypothermic circulatory arrest, but could not supply sufficient cerebral blood flow to maintain brain function. Selective cerebral perfusion was the safest method for each reconstruction that requires cerebral protection for 90 minutes.