Update on Techniques for Neuroprotection during Hypothermic Arrest

Surgical repair of the ascending aorta and aortic arch that employs cardiopulmonary bypass (CPB), often with the use of deep hypothermic circulatory arrest (DHCA), allows for lifesaving therapy. In doing so, however, it also represents a unique injury paradigm leading to derangements in numerous homeostatic pathways. Organ injury, most notably cerebral injury, may result as a consequence of these various perturbations in inflammatory and oxidative stress pathways that have been implicated in the pathogenesis of cerebral injury. [1-3] Adverse cerebral outcomes are a major source of morbidity after major cardiovascular surgery, particularly after aortic surgery. Despite advances in surgical, anesthetic, and neuroprotective strategies, the incidence of perioperative stroke after thoracic aortic surgery remains approximately 4-15%, while temporary neurological dysfunction (TND) and cognitive decline have a documented incidence of 16-22% and up to 30%, respectively. [4-8] The incidence of adverse cerebral outcomes is particularly high in patients undergoing emergent repair / replacement of the ascending aorta or aortic arch. [7,9] Preventing or treating perioperative cerebral injury remains difficult, partly because the underlying mechanisms associated with the ischemia-reperfusion injury introduced by DHCA and CPB are incompletely understood.