Comparison of short-term outcomes of mild and moderate hypothermic circulatory arrest in aortic arch surgery: a single center retrospective cohort study

BACKGROUND: Aortic arch surgery is one of the major challenges in modern aortic surgery, special cerebral and visceral organ protective strategies are still under progress. Whether mild hypothermic circulatory arrest (Mi-HCA) can be safely used in aortic arch surgery (AAS) is the focus of attention. METHODS: From January 2017 to June 2021, a retrospective cohort study of 138 consecutive patients was conducted at Beijing Anzhen Hospital. The study comprised patients who underwent AAS performed by a single surgeon during moderate-to-mild HCA. According to the core temperature at the beginning of circulatory arrest, the patients were divided into three groups: T(1) group (n=45; 25.76±0.75 ℃), T(2) group (n=43; 28.79±0.81 ℃), T(3) group (n=50; 31.46±0.79 ℃). Perioperative clinical data were analyzed to assess the differences between groups. RESULTS: In this cohort, the average durations of the operation, cardiopulmonary bypass (CPB), cross-clamp, circulatory arrest, and selective antegrade cerebral perfusion (SACP) were 6.53±1.48 h, 184.07±56.69 min, 101.04±37.92 min, 23.01±9.86 min, and 27.18±11.52 min, respectively. We observed new postoperative permanent neurological dysfunction (PND) in 12 patients (8.7%) and transient neurological dysfunction in 18 patients (13.04%). The in-hospital mortality rate was 6.52% (n=9). The durations of the operation, CPB, cross-clamp, circulatory arrest, and SACP were significantly reduced in the Mi-HCA group (i.e., T(3) group, P<0.001; P<0.001; P<0.001; P=0.002; P<0.001, respectively). The incidence of PND and major adverse events (MAEs) were significantly reduced among the three groups (P=0.025; P=0.035). Multivariate logistic regression analysis models showed that Mi-HCA was an independent protective factor in reducing postoperative MAEs [relative risk (RR) =0.12; 95% confidence interval (CI): 0.02–0.90; P=0.0385]. CONCLUSIONS: The short-term outcomes of Mi-HCA combined with SACP in AAS were acceptable. Similarly, the protection of distal organs and the spinal cord was observed compared to the MHCA strategy, and a lower incidence of MAEs was obtained. Current data suggest that the mild hypothermia strategy can be safely applied for AAS.