ObjectiveTo investigate the results of emergent aortic arch replacement using moderate hypothermic circulatory arrest and unilateral antegrade cerebral perfusion (MHCA+UACP).MethodsWe retrospectively analyzed the clinical data of 146 patients who underwent emergent aortic arch replacement using MHCA+UACP in our institution from January 2008 to June 2018. There were 111 males and 35 females aged 60.3±7.2 years. According to different surgical approaches, patients were divided into two groups: a total arch replacement (TAR) group (n=104) and a semi arch replacement (SAR) group (n=42). Right axillary artery was cannulated for cardiopulmonary bypass (CPB) and cerebral perfusion. Core temperature at the onset of MHCA was 23.4±1.4 ℃. UACP was initiated at 18-22 ℃ with the flow of 5-10 ml/(kg·min). Flow was adjusted to maintain cerebral perfusion pressure of 50–60 mm Hg.ResultsCPB time was 235.0±42.0 min. Aortic clamp time was 154.0±29.0 min. Circulatory arrest (CA) time was 48.1±13.0 min. The CPB time and CA time of the TAR group were longer than those of SAR group. Overall mortality rate was 9.6%. Complications included permanent neurological dysfunction (PND), temporary neurological dysfunction (TND), acute kidney injury (AKI) requiring dialysis and delayed extubation (mechanical ventilation time >72 hours). Overall incidence of PND and TND was 2.7% and 6.8%, respectively. The incidence of AKI requiring dialysis was 4.1%. The incidence of delayed extubation was 21.9%. No difference of mortality rate or incidence of complications was found between the two groups. The average follow-up was 63.0±33.1 months. The 5-year survival rate was 72.6% in the TAR group and 85.5% in the SAR group.ConclusionEmergent aortic arch replacement using MHCA+UACP can be accomplished with excellent results.