• acute aortic syndrome
• aortic arch surgery
• dissection
• mild hypothermia

Objectives: During the last years there has been a shift toward progressive reduction in core temperature during aortic arch surgeries (AAS) requiring circulatory arrest (CA) to reduce surgical times and risk of bleeding. This strategy could however impact neurological and renal outcomes. Aim of this single center study is to assess the safety of very mild hypothermic CA in patients who underwent AAS with a core temperature close or above 30° C.
Methods: All consecutive patients who electively or urgently underwent AAS requiring CA at our center were included. In all cases antegrade selective cerebral perfusion was performed and hypothermia was maintained only during CA period. We assessed in-hospital mortality, postoperative acute kidney injury (AKI), neurological events and bleeding. Multivariable analysis was performed to evaluate the predictors of the three outcomes.
Results: We included 172 patients, 91% presented with an acute aortic syndrome. Of them 17% had neurological deficits at baseline and 8.6% were intubated at arrival, GEERADA score was 22±13%. Mean bladder temperature was 30±1.7° C, mean cardiopulmonary by-pass (CPB) and CA times were 200±72 and 14 (12-18) minutes respectively. Median cerebral perfusion time was 34 (23-71) minutes, bilateral antegrade cerebral perfusion was performed in 93% of cases and unilateral in 7%. Ninety-two (53%) required aortic arch replacement with reimplantation of at least two of the three supraoptic vessels while 8 patients (5%) required hemiarch replacement (reimplantation of the brachiocephalic trunk). Packing for non-controlled bleeding was necessary in 6% of cases and 11% patients required surgical revision for bleeding within the first 24 hours from surgery. We had 2 (1%) fatal, 19 (11%) disabling and 8 (5%) non disabling strokes while 6% of patients developed renal impairment requiring temporary veno-venous hemofiltration. Thirty-day mortality was 10%. Bladder temperature was not associated with outcomes while retrograde perfusion and GERAADA score were predictors of neurological events. GERAADA score also tended to predict postoperative bleeding while the involvement of descending aorta tended to predict renal impairment.
Conclusions: CA with core temperature above 30° C paired to selective bilateral cerebral perfusion resulted safe in patients undergoing aortic arch surgery, also in case of acute aortic syndromes.