Background: Although hypothermic circulatory arrest (HCA) combined with selective cerebral perfusion (SCP) is a safe strategy for aortic arch surgery, neither the optimal temperature of hypothermia nor the optimal SCP flow rate has been clearly determined. We have since 2002 gradually elevated the temperature of HCA from 20 degrees C to 28 degrees C for aortic arch surgery. This study explored the impact of different temperatures during HCA with SCP on neurologic complications.
Methods: Since January 2002, 229 patients have undergone aortic arch replacement (mean age, 70.8 +/- 9.7 years; 156 male) with HCA and SCP through median sternotomy in our institution. Eighty-one patients were cooled to 20 degrees C (group A), 81 were cooled to 25 degrees C (group B), and 67 were cooled to 28 degrees C (group C). The brachiocephalic and left common carotid arteries were perfused separately during SCP in all cases. The left subclavian artery was additionally perfused in group C. Twenty-two operations in group A, 17 in group B, and 6 in group C were performed emergently (p = 0.58). The SCP flow rate was maintained at approximately 10 mL.kg(-1).min(-1) in groups A and B and approximately 15 mL.kg(-1).min(-1) in group C to keep blood pressure in the temporal artery at approximately 60 mm Hg.
Results: The early mortality rate was 3.7% (3 of 81) in group A, 0% in group B, and 1.5% (1 of 67) in group C (p = 0.19). Postoperative stroke occurred in 2 patients (2.5%) in group A, in 3 (3.7%) in group B, and in 4 (6.0%) in group C (p = 0.55). Postoperative transient neurologic dysfunction occurred in 7 patients (8.6%) in group A, in 9 patients (11.1%) in group B, and in 4 patients (6.0%) in group C (p = 0.54). No patients in any group had postoperative paraplegia. The mean durations of circulatory arrest were 64 +/- 21 minutes in group A, 49 +/- 14 minutes in group B, and 46 +/- 13 minutes in group C (p < 0.0001). The mean durations of SCP were 145 +/- 67 minutes in group A, 116 +/- 48 minutes in group B, and 111 +/- 61 minutes in group C (p = 0.0007). Mean SCP flow rates were 8.8 +/- 1.9 mL.kg(-1).min(-1) in group A, 10.5 +/- 3.1 mL.kg(-1).min(-1) in group B, and 19.0 +/- 4.2 mL.kg(-1).min(-1) in group C (p < 0.0001).
Conclusions: The rate of postoperative neurologic events did not increase with use of higher temperature. The temperature during HCA could be safely increased to 28 degrees C with high SCP flow rate. Use of moderate HCA with SCP during aortic arch replacement permits radical reconstruction of the aortic arch and can avoid the need for deep hypothermia.