Aortic arch aneurysm surgery: what is the gold standard temperature in the absence of randomized data?

Machine learning and decision making in aortic arch repair

BACKGROUND

Decision making during aortic arch surgery regarding cannulation strategy and nadir temperature are important in reducing risk, and there is a need to determine the best individualized strategy in a data-driven fashion. Using machine learning (ML), we modeled the risk of death or stroke in elective aortic arch surgery based on patient characteristics and intraoperative decisions.

METHODS

The study cohort comprised 1323 patients from 9 institutions who underwent an elective aortic arch procedure between 2002 and 2021. A total of 69 variables were used in developing a logistic regression and XGBoost ML model trained for binary classification of mortality and stroke. Shapely additive explanations (SHAP) values were studied to determine the importance of intraoperative decisions.

RESULTS

During the study period, 3.9% of patients died and 5.4% experienced stroke. XGBoost (area under the curve [AUC], 0.77 for death, 0.87 for stroke) demonstrated better discrimination than logistic regression (AUC, 0.65 for death, 0.75 for stroke). From SHAP analysis, intraoperative decisions are 3 of the top 20 predictors of death and 6 of the top 20 predictors of stroke. Predictor weights are patient-specific and reflect the patient's preoperative characteristics and other intraoperative decisions. Patient-level simulation also demonstrates the variable contribution of each decision in the context of the other choices that are made.

CONCLUSIONS

Using ML, we can more accurately identify patients at risk of death and stroke, as well as the strategy that better reduces the risk of adverse events compared to traditional prediction models. Operative decisions made may be tailored based on a patient's specific characteristics, allowing for maximized, personalized benefit.

Systematic review and network meta-analysis of various nadir temperature strategies for hypothermic circulatory arrest for aortic arch surgery

BACKGROUND

The optimal nadir temperature for hypothermic circulatory arrest during aortic arch surgery remains unclear. We aimed to assess and compare clinical outcomes of all three temperature strategies (deep, moderate, and mild hypothermia) using a network meta-analysis.

METHODS

After literature search with MEDLINE and EMBASE through December 2021, studies comparing clinical outcomes with deep (<20°C), moderate (20-28°C), or mild (>28°C) hypothermic circulatory arrest were included. The outcomes of interest were perioperative mortality, stroke, transient ischemia attack (TIA), acute kidney injury (AKI), postoperative bleeding, operative time, and length of hospital stay.

RESULTS

Twenty-four comparative studies were identified, including 6018 patients undergoing aortic arch surgery using hypothermic circulatory arrest (deep: 2,978, moderate: 2,525, and mild: 515). Compared to deep hypothermia, mild and moderate hypothermia were associated with lower mortality (mild vs. deep: odds ratio [OR] 0.50; 95% confidence interval (CI) 0.29-0.87, moderate vs. deep: OR 0.68; 95% CI 0.54-0.86). In addition, mild hypothermia was associated with lower stroke (OR 0.50; 95% CI 0.28-0.89), AKI (OR 0.36; 95% CI 0.15-0.88) and postoperative bleeding (OR 0.55; 95% CI 0.31-0.97) compared to deep hypothermia. There was no significant difference between mild and moderate hypothermia in mortality, AKI or bleeding occurrence, while mild hypothermia was associated with shorter operative time and hospital stay. There was no significant difference in TIA rate among three groups.

CONCLUSIONS

Mild hypothermia was associated with overall more favorable clinical outcomes with comparable neurological complications compared to deep hypothermia. Furthermore, considering the shorter operative time and hospital stay compared with moderate hypothermia, mild hypothermia may be warranted when appropriate adjunctive cerebral perfusion is employed.

Application of the aortic balloon occlusion technique in Sun's procedure: A single-center study

OBJECTIVES

To study the impact of a balloon occlusion (BO) technique in stented elephant trunk implantation in Sun's procedure for acute Stanford type A aortic dissection (AAAD) on important postoperative organ complications and patient rehabilitation.

METHODS

Eighty-five patients with AAAD who underwent Sun's procedure from January 2019 to January 2020 were selected. Cases were divided into two groups based on whether the aortic BO technique was used in stented elephant trunk implantation: the BO group and the nonballoon occlusion (NBO) group. The collected data included the patients' clinical characteristics, operative data, postoperative complications and recovery. We applied statistical software to study the impact of a BO technique in stented elephant trunk implantation in Sun's procedure.

RESULTS

A total of 85 patients with AAAD underwent Sun's procedure. A total of 29 used BO technique, 56 did not use. The circulatory arrest time in the BO group was controlled within 8.07 ± 2.33 min, and the nasopharyngeal temperature dropped to 28°C. Overall postoperative complications were less frequent in BO group than NBO group (52% vs. 75%; p = .030). Using BO technique, we reduced the 24-h drainage volume, and lowered the occurrence of hypoxemia (48%), liver dysfunction (10%), and median tracheal intubation time was 37 h (range: 12.5-106 h), median intensive care unit (ICU) time was 65 h (range: 17-207 h).

CONCLUSIONS

During total aortic arch replacement and stented elephant trunk surgery for AAAD, we used the aortic BO technique, which avoids deeper hypothermia and effectively shortens circulatory arrest times. This approach is helpful for reducing the incidence of postoperative complications and shortening the intensive care unit time. This method also reduces the patient's medical burden and facilitates faster recovery.

Open aortic arch surgery: the gold standard method

Aortic arch pathologies are complex and treating them requires close team collaboration and technical skills to provide safe outcomes with low morbidity and mortality rates. Such challenges are facing both aortic and vascular surgeons. Open aortic arch repair has been the standard method of practice in all cases of aortic arch pathologies for the last four decades since the very first successful published case series by Griepp et al. during 1975. However, since then, repair of multi-segmented thoracic aortic pathologies has been explored through endovascular techniques; this is with or without open repair as a one-stage procedure especially in high-risk and elderly patients. Although the role of endovascular techniques in thoracoabdominal aorta is well established, its utilization as solo technique in aortic arch pathologies remains debatable. In this review, we highlight current evidences behind using open, endovascular, and hybrid procedures in aortic arch surgery.