Short-term outcomes of mild (≥30 ℃) vs. moderate hypothermic circulatory arrest in aortic arch surgery

Hypothermia and antegrade cerebral perfusion (ACP) strategies in open aortic arch surgery (AAS) have improved significantly. The significance of the gradual temperature rise to mild hypothermia is quite apparent, however, its safety remains a challenge. Therefore, our objective was to explore the safety and efficacy of mild hypothermic circulatory arrest (Mi-HCA, ≥30 ℃).

This retrospective cohort study enrolled in a total of 372 patients, and was performed at the Beijing Anzhen Hospital between January 2017 and November 2022. Among the 372 patients, 81 received AAS at ≥30 ℃, and the remaining 291 received the same at 22-29.9 ℃. Most acute type A aortic dissection (ATAAD) patients received total arch replacement (TAR) and frozen elephant trunk (FET) operation.

Mi-HCA patients exhibited strongly augmented systemic temperature (26.19±1.63 vs. 31.40±0.79 ℃, P<0.01). The surgical, cardiopulmonary bypass (CPB), cross-clamp, circulatory arrest, and ACP durations were drastically diminished among Mi-HCA patients (all P<0.01). Moreover, the major adverse events (MAEs) incidence of Mi-HCA patients was significantly decreased (25.43% vs. 14.81%, P<0.05). Simultaneously, the Mi-HCA strategy also exhibited enhanced protection of blood cells, as well as myocardial and hepatic function. Nevertheless, multivariate logistic regression analysis revealed that Mi-HCA strategy (≥30 ℃) was not a stand-alone risk factor for MAEs following AAS.

The short-term outcomes and safety of Mi-HCA, in combination with ACP, in AAS are satisfactory. Additionally, relative to the traditional moderate hypothermic circulatory arrest (MHCA) approach, it can substantially decrease operation duration while improving patient clinical outcomes.