Invited commentary

Abstract

Three management strategies have been described for cerebral protection during aortic arch reconstruction. Hypothermic circulatory arrest (HCA) lowers the brain temperature with a concomitant reduction in cerebral metabolism. The protection imparted by the reduced cerebral metabolic rate is, however, time-dependent. It is oftentimes difficult to perform a complex arch reconstruction in the 45 to 60 minutes recommended as the safe limit for HCA. Retrograde cerebral perfusion (RCP) is, arguably, the most widely employed but least well studied of the three techniques. Selective superior vena caval perfusion cannot meet the brain’s metabolic demand due to perfusate runoff into the systemic venous circulation. The advantage of RCP lies in the continuous washout of particulate emboli from the head vessels. Atheromatous debris from arch aneurysms are thought to be the primary etiologic factor for neurologic sequelae following arch aneurysm repair. The third management strategy, antegrade cerebral perfusion (ACP), is employed by Takahara and colleagues in the current series with superb results. ACP provides better nutritive flow to the brain than either HCA or RCP. Although cannulation of the potentially diseased arch vessels can lead to atheroma embolization or exacerbation of dissection flaps, the enhanced cerebral protection allows the surgeon to operate on the aortic arch with little time constraint. In the current series, the authors cannulate diseased arch vessels under direct vision (using HCA) and employ pH-stat management to abolish cerebral autoregulation. ACP is infrequently employed, as the cardiopulmonary bypass circuit is more complex (multiple roller heads) and the cannulation scheme is more cumbersome. The reported postoperative temporary neurologic dysfunction and stroke rates of 3% and 2%, respectively, should make the reader reconsider utilizing this management strategy in the patient who requires a complex aortic arch reconstruction.