Cerebral protection using deep hypothermic circulatory arrest versus retrograde cerebral perfusion for aortic hemiarch reconstruction

Preoperative Hematocrit Is Not Associated With Stroke After Surgery for Acute Type A Aortic Dissection

OBJECTIVE

To determine the impact of hematocrit on adverse neurologic events after acute type A aortic dissection (ATAAD) repair under deep hypothermic circulatory arrest.

DESIGN

Retrospective study of consecutive aortic surgeries from 2010 to 2021.

SETTING

Single institution.

PARTICIPANTS

Patients undergoing open ATAAD repairs, excluding those with preoperative cerebral malperfusion syndrome (defined as neurologic deficit with radiographic evidence of cerebral branch vessel malperfusion).

INTERVENTIONS

Patients were split into three groups: normal, low, and high hematocrit.

MEASUREMENTS & MAIN RESULTS

A total of 527 patients were included, of which 355 (67.3%) had normal hematocrit, 143 (27.1%) had low hematocrit, and 29 (5.5%) had high hematocrit. Overall, 20 (3.8%) patients had a postoperative stroke, which was comparable across groups (p = 0.59). Patients with normal hematocrit had lower in-hospital mortality (p = 0.02) and lower transfusion rates (p < 0.001), while re-exploration for bleeding was similar across groups (p = 0.68). After multivariable adjustment, there was no association between hematocrit and postoperative stroke (odds ratio [OR]: 1.00, 95% confidence interval [CI]: 0.99, 1.00, p = 0.79). Compared with normal hematocrit, there was no association between low hematocrit (OR: 1.59, 95% CI: 0.77, 3.28, p = 0.21) or high hematocrit (OR: 2.48, 95% CI: 0.74, 8.29, p = 0.14) and in-hospital mortality.

CONCLUSIONS

Preoperative hematocrit was not associated with stroke or mortality after ATAAD repair. The rheologic effect of hematocrit on cerebral perfusion under deep hypothermia may be minimal.

Optimization of Hypothermic Protocols for Neurocognitive Preservation in Aortic Arch Surgery: A Literature Review

Shifts from deep to moderate hypothermic circulatory arrest (HCA) in aortic arch surgery necessitate an examination of their differential impacts on neurocognitive functions, especially structured verbal memory, given its significance for patient recovery and quality of life. This study evaluates and synthesizes evidence on the effects of deep (≤20.0 °C), low-moderate (20.1-24.0 °C), and high-moderate (24.1-28.0 °C) hypothermic temperatures on structured verbal memory preservation and overall cognitive health in patients undergoing aortic arch surgery. We evaluated the latest literature from major medical databases such as PubMed and Scopus, focusing on research from 2020 to 2024, to gather comprehensive insights into the current landscape of temperature management during HCA. This comparative analysis highlights the viability of moderate hypothermia (20.1-28.0 °C), supported by recent trials and observational studies, as a method to achieve comparable neuroprotection with fewer complications than traditional deep hypothermia. Notably, low-moderate and high-moderate temperatures have been shown to support substantial survival rates, with impacts on structured verbal memory preservation that necessitate careful selection based on individual surgical risks and patient profiles. The findings advocate for a nuanced approach to selecting hypothermic protocols in aortic arch surgeries, emphasizing the importance of tailoring temperature management to optimize neurocognitive outcomes and patient recovery. This study fills a critical gap in the literature by providing evidence-based recommendations for temperature ranges during HCA, calling for ongoing updates to clinical guidelines and further research to refine these recommendations. The implications of temperature on survival rates, complications, and success rates underpin the necessity for evolving cardiopulmonary bypass techniques and cerebral perfusion strategies to enhance patient outcomes in complex cardiovascular procedures.

Early outcome of simplified total arch reconstruction under mild hypothermia (30-32 °C) with distal aortic perfusion

OBJECTIVE

We designed a simplified total arch reconstruction (s-TAR) technique which could be performed under mild hypothermia (30-32 °C) with distal aortic perfusion. This study aimed to compare its efficacy of organ protection with the conventional total arch reconstruction (c-TAR).

METHODS

We reviewed the clinical data of 195 patients who had ascending aortic aneurysm with extended aortic arch dilation and underwent simultaneous ascending aorta replacement and TAR procedure between January 2018 and December 2022 in our center. 105 received c-TAR under moderate hypothermia (25-28 °C) with circulatory arrest (c-TAR group); rest 90 received s-TAR under mild hypothermia (30-32 °C) with distal aortic perfusion (s-TAR group).

RESULTS

The s-TAR group demonstrated shorter CPB time, cross-clamp time and lower body circulatory arrest time compared with the c-TAR group. The 30-day mortality was 2.9% for the c-TAR group and 1.1% for the s-TAR group (P = 0.043). The mean duration of mechanical ventilation was shorter in the s-TAR group. Paraplegia was observed in 4 of 105 patients (3.8%) in the c-TAR group, while no such events were observed in the s-TAR group. The incidence of temporary neurologic dysfunction was significantly higher in the c-TAR group. The incidence of permanent neurologic dysfunction also showed a tendency to be higher in the c-TAR group, without statistical significance. Furthermore, the incidence of reoperation for bleeding were significantly lower in the s-TAR group. The rate of postoperative hepatic dysfunction and all grades of AKI was remarkably lower in the s-TAR group. The 3-year survival rate was 95.6% in the s-TAR group and 91.4% in the c-TAR group.

CONCLUSIONS

s-TAR under mild hypothermia (30-32℃) with distal aortic perfusion is associated with lower mortality and morbidity, offering better neurological and visceral organ protection compared with c-TAR.

Does deep hypothermic circulatory arrest with versus without retrograde cerebral perfusion affect the outcomes after proximal aortic arch aneurysm and acute type A aortic dissection repair? Different pathologies and cerebral protection techniques with similar results

Hypothermic circulatory arrest is used for proximal and total aortic arch correction in patients with aortic arch aneurysm and acute or chronic type A aortic dissection. Different cerebral perfusion techniques have been proposed for reducing morbidity and mortality rate. The study of Arnaoutakis et al. showed that deep hypothermic circulatory arrest with or without retrograde cerebral perfusion for proximal aortic aneurysm and acute type A aortic dissection correction had similar results with regard to morbidity and mortality rate. In addition, the short circulatory arrest time contributes for favorable outcomes of these patients. Although antegrade cerebral perfusion with hypothermic circulatory is widely used by many cardiac surgeons, deep hypothermic circulatory arrest with or without retrograde cerebral perfusion remains an alternative and safe method for brain protection in patients undergoing proximal aortic arch aneurysm or acute type A aortic dissection repair.