What is the safe time limit for retrograde cerebral perfusion with hypothermic circulatory arrest in aortic surgery?

Retrograde cerebral perfusion technique has been used recently for the protection of the brain during circulatory arrest in aortic surgery. However, the safe time limit for retrograde cerebral perfusion has not been known. From July 1993 to April 1995, 20 patients underwent thoracic aortic operations using retrograde cerebral perfusion technique with hypothermic circulatory arrest. Retrograde cerebral perfusion was used to repair the aortic dissection in seventeen patients, aortic arch aneurysm in two patients and annuloaortic ectasia with severely calcified ascending aorta in one patient. The mean duration of retrograde cerebral perfusion was 74 minutes (19-135 min). There were six patients in whom retrograde cerebral perfusion exceeded 90 minutes, however no patients except one who had preoperative cerebral infarction showed any neurological deficits. There were two operative deaths and three hospital deaths, neither of which was related to postoperative neurological complications. Retrograde cerebral perfusion safely may provide a longer period of circulatory arrest at least up to 90 minutes.