Prolonged Periods of Antegrade Cerebral Perfusion Are Safe During Elective Arch Surgery

Neurocognitive Dysfunction After Short (<20 Minutes) Duration Hypothermic Circulatory Arrest

BACKGROUND

It has long been held that the safe duration of hypothermic circulatory arrest (HCA) is at least 25 to 30 minutes. However, this belief is based primarily on clinical outcomes research and has not been systematically investigated using more sensitive brain imaging and neurocognitive assessments.

METHODS

This exploratory substudy of the randomized Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest (GOT ICE) trial, which compared outcomes for deep vs moderate hypothermia during aortic arch surgery, investigated the frequency of neurocognitive and structural and functional magnetic resonance imaging (MRI) deficits with HCA of short (<20 minutes) duration. Neurocognitive deficit was defined as ≥1 SD decline in ≥1 of 5 cognitive domains on neurocognitive testing.

RESULTS

Of 228 GOT ICE participants with complete 4-week cognitive data, 74.6% (n = 170 of 228) had HCA durations <20 minutes, including 59 patients randomized to deep hypothermia (<20.0 °C), 55 patients randomized to low-moderate (20.1-24.0 °C) hypothermia, and 56 randomized to high-moderate (24.1-28.0 °C) hypothermia. Of these participants, cognitive deficit was detected 4 weeks postoperatively in ∼40% of patients in all 3 groups (deep hypothermia, 22 of 59 [37.3%]; low-moderate hypothermia, 23 of 55 [41.8%]; and high-moderate hypothermia, 24 of 56 [42.9%]). Furthermore, in a subset of patients with complete MRI data (n = 43), baseline to 4-week postoperative right frontal lobe functional connectivity change was inversely associated with HCA duration (range, 8-17 minutes; P for familywise error rate < .01).

CONCLUSIONS

Even short durations of HCA result in cognitive deficits in ∼40% of patients, independent of systemic hypothermia temperature. HCA duration was inversely associated with frontal lobe functional MRI connectivity, a finding suggesting that this brain region may be preferentially sensitive to HCA. Surgeons should be aware that even short durations of HCA may not provide complete neuroprotection after aortic arch surgery.

Safety of prolonged bilateral antegrade cerebral perfusion in aortic arch surgery with moderate hypothermia

OBJECTIVES

This study investigates the impact of bilateral antegrade cerebral perfusion (ACP) time on outcomes in aortic arch surgery.

METHODS

In total, 961 patients underwent either hemiarch (n = 385) or total arch replacement (n = 576) with bilateral ACP and moderate hypothermia management between 2006 and 2020 across 2 aortic centres. ACP time was categorized into 4 groups (≤30 min: n = 169, 30-60 min: n = 298, 60-90 min: n = 261, >90 min: n = 233). Inverse probability of treatment weighting yielded a well-balanced cohort among the 4 groups except for the cannulation site. Adjusted cubic spline and multivariable logistic analysis were performed, controlling for surgical procedure, cannulation site and cardiopulmonary bypass (CPB) time, to identify the relationship between ACP time and major in-hospital complications including mortality, stroke, acute renal failure and prolonged ventilation.

RESULTS

There remained a significant difference in surgical procedures and CPB time in the matched cohort. The incidences of mortality and stroke did not show significant trend (P = 0.052 and 0.717, respectively). Cubic spline curves showed that odds ratios did not increase linearly for any complications with increasing ACP time. Furthermore, ACP time, even exceeding 90 min, was not associated with complication rates [mortality: odds ratio = 1.459 (0.368-6.049), P = 0.595; stroke: 0.310 (0.058-1.635), P = 0.166; renal failure: 1.744 (0.521-6.094), P = 0.374; prolonged ventilation: 1.502 (0.535-4.286), P = 0.442], whereas CPB time was associated with mortality and prolonged ventilation.

CONCLUSIONS

Even when ACP time exceeded 90 min, it was not associated with major in-hospital complications, questioning its validity as a marker for surgical insult.