Moderate Versus Deep Hypothermia With Unilateral Selective Antegrade Cerebral Perfusion for Acute Type A Dissection.

Background: Despite improved results with surgical therapy for acute type A aortic dissection (ATAAD), there remains a lack of consensus regarding the optimal method of cerebral protection and circulation management during ATAAD. The purpose of this study is to determine whether in the setting of antegrade cerebral perfusion, moderate hypothermic circulatory arrest (MHCA) provides equivalent cerebral and visceral protection as deep hypothermic circulatory arrest (DHCA) for patients undergoing emergent ATAAD repair.

Methods: A review of the Emory aortic surgery database from 2004 to 2014 identified 288 patients who underwent ATAAD with right axillary artery cannulation, unilateral selective antegrade cerebral perfusion (uSACP), and hypothermic circulatory arrest (HCA). In all, 88 patients underwent HCA at 24 °C or lower (DHCA), and 206 patients underwent HCA at more than 24 °C (MHCA). Major adverse outcomes of death, stroke, temporary neurologic dysfunction, and dialysis-dependent renal failure were examined.

Results: The groups were well matched for age and major comorbidities. The DHCA patients underwent HCA at lower temperatures (DHCA 21.6 ± 3.1 °C vs MHCA 27.4 ± 1.6 °C, p < 0.01). There were no significant differences in cardiopulmonary bypass, cross-clamp, or HCA times. Mortality was 14.6% for DHCA patients, and 9.2% for MHCA patients (p = 0.17). There was no significant difference in stroke, temporary neurologic dysfunction, or dialysis-dependent renal failure. There was no association with either MHCA plus uSACP or DHCA plus uSACP and any of the major adverse outcomes (p > 0.05).

Conclusions: Moderate HCA with uSACP is an effective circulation management strategy that provides excellent cerebral and visceral protection during emergent ATAAD repair. In the setting of antegrade cerebral perfusion, deep hypothermia does not provide any additional benefit.