Con-debate: short circulatory arrest times in arch reconstructive surgery: is simple retrograde cerebral perfusion or hypothermic circulatory arrest as good or better than complex antegrade cerebral perfusion for open distal involvement or hemi-arch?

Abstract

Aortic arch open surgery continues to represent a formidable challenge for heart surgeons. In fact, the interruption of physiological brain perfusion is a major detrimental effect during the systemic circulatory arrest resulting in a series of neurological complications. In order to protect the brain from these injuries, three techniques have been proposed and widely utilized as a means of protecting the brain: deep hypothermic circulatory arrest (DHCA), retrograde cerebral perfusion (RCP) and antegrade cerebral perfusion (ACP). The basis for all the techniques is the protection afforded by hypothermia with the consequent metabolic suppression. The duration of cerebral protection is an important consideration, which has to be evaluated in the selection of the appropriate cerebral protection method. In fact, although the three techniques have provided for safer thoracic aortic surgery and increased perfusion times, the time of brain perfusion is not unlimited and in light of this, debate remains as to the better cerebral circulatory management technique for arch reconstructive surgery with short circulatory arrest times. It is universally accepted that DHCA, although is a simple and valid method of brain protection, has the main disadvantage of a limited “safe” time of circulatory arrest. In fact, the “safe” time-period of DHCA to prevent neurologic injuries has been showed to be less than 45 minutes at 18 °C, with some authors who showed an increase of the rate of neurologic deficit with DHCA-time ranged between 30 and 50 minutes (1). It is clear how, in order to increase the “safe” time of DHCA, adjunct techniques of RCP and ACP with various levels of hypothermia have been adopted. In 1992, Ueda and co-workers published the first series on continuous RCP in combination with DHCA during aortic arch surgery (2). Before DHCA introduction, the technique was realized using the bypass connecting the arterial and venous lines of the extracorporeal circuit to reverse the flow into the superior vena cava cannula (2,3). In this landmark paper, circulatory arrest times ranged from 11 to 56 minutes and nasopharyngeal temperatures ranged from 16 to 18 °C (2). Thereafter, the same technique evolved, operative times shorten, early mortality and morbidity improved and many other series finally validated the efficacy of RCP for cerebral protection (1,4-7). However, during the same decades, the excellent results coming from the ACP with a direct cannulation of the supraaortic vessels progressively clouded the retrograde technique (8-10). Although potential benefits of the RCP have been proved in terms of the embolic debris, intracranial hypothermia maintenance and cerebral metabolic support, other possible disadvantages have been identified in clinical and experimental studies. Reich et al. performed preoperative and postoperative neuropsychological evaluation in 21 patients undergoing DHCA and RCP during elective thoracic aortic repair (11). The overall cognitive and memory dysfunctions had strong associations with RCP, even when controlling separately for age and cerebral ischemic time. In another study, Okita Viewpoint on Cardiac Surgery