Role of Moderate Hypothermia and Antegrade Cerebral Perfusion during Repair of Type A Aortic Dissection

Optimizing Therapeutic Hypothermia Depths in Acute Type A Aortic Dissection Repair

INTRODUCTION

Existing evidence regarding the impact of hypothermic circulatory arrest (HCA) depth in acute type A aortic dissection (ATAAD) repair lacks robustness concerning blood loss and mortality. We aimed to assess whether using mild and moderate HCA (MMHCA) versus deep and profound HCA (DPHCA) in ATAAD repair is associated with reduced bleeding risk, lower in-hospital mortality, and improved long-term survival.

METHODS

This retrospective cohort study spanned from 2003 to 2023. ATAAD repair patients were identified from hospital records, with exclusion criteria applied to those who died before surgery, those with symptoms lasting longer than 14 d, and those who operated on without HCA. Patients in the DPHCA group underwent surgery with HCA (T ≤ 20°C), while those in the MMHCA group had temperatures ranging from 34°C to 20.1°C.

RESULTS

Out of 549 eligible ATAAD patients, the MMHCA group exhibited a reduced rate of chest re-exploration for bleeding (39% versus 14%, P < 0.005), decreased blood loss after surgery (1637 mL versus 1045 mL, P < 0.005), and lower volumes for red blood cell transfusions (1375 mL versus 903 mL, P < 0.005) compared with the DPHCA group. Additionally, the MMHCA group had lower crude and age- and sex-adjusted in-hospital mortality rates, with a mortality rate ratio of 0.65 (P = 0.003). Cox regression analysis revealed a 25% reduction in long-term mortality for the MMHCA group compared with the DPHCA group (hazard ratio = 0.75; P = 0.045).

CONCLUSIONS

ATAAD repair using MMHCA and antegrade cerebral perfusion is associated with lower blood loss and improved immediate and long-term survival.

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

Background

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 ℃).

Methods

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.

Results

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.

Conclusions

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.

Study on the relationship among typhoon, climate change, and acute Stanford type A aortic dissection in southern of Zhejiang in China

BACKGROUND

The aim of this study was to investigate the relationship between typhoon, climate change, and acute Stanford type A aortic dissection (TAAD) in southern of Zhejiang Province in China.

METHOD

371 patients with TAAD were admitted to three hospitals (the aortic dissection center) in southern of Zhejiang Province, China from January 2015 to December 2020, and data were retrospectively collected, the data included (1) the number of patients admitted in different months and seasons, (2) daily meteorological data in southern of Zhejiang Province, and (3) typhoon information were retrospectively analyzed.

RESULTS

The number of TAAD occurred in winter was the highest and in summer was the lowest. The incidence of TAAD was correlated with minimum temperature, maximum wind speed, mean wind speed, and water vapor pressure (P < 0.05). Maximum wind speed (RR 0.37; 95% CI 0.17 to 0.80, P = 0.01) and water vapor pressure (RR 0.96; 95% CI 0.92 to 1, P = 0.03) were the protective factor. The occurrence incidence of TAAD under the influence of typhoon climate was less than that during the period not affected by typhoon (P < 0.05).

CONCLUSION

There was a correlation between typhoon, climate change, and the occurrence of TAAD in southern Zhejiang Province. Wind speed, vapor pressure, and typhoon may be protective factors.

Deep Versus Moderate Hypothermia in Acute Type A Aortic Dissection: A Propensity-Matched Analysis

BACKGROUND

The ideal temperature for hypothermic circulatory arrest (HCA) during acute type A aortic dissection (ATAAD) repair has yet to be determined. We examined the clinical impact of different degrees of hypothermia during dissection repair.

METHODS

Out of 240 cases of ATAAD between June 2014 and December 2019, 228 patients were divided into two groups according to lowest intraoperative temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). From this, 74 pairs of propensity-matched patients were analysed with respect to operative data and short-term clinical outcomes. Independent predictors of a composite outcome of 30-day mortality and stroke were identified.

RESULTS

Mean lowest temperature was 25.5±3.9°C in the MHCA group versus 16.0±2.9°C in DHCA. Overall 30-day mortality of matched cohort was 11.5% (17 deaths), there were no significant different between matched groups. Cardiopulmonary bypass (CPB) times were longer in DHCA (221.0±69.9 vs 190.7±74.5 mins, p=0.01). Antegrade cerebral perfusion (ACP) during HCA predicted a lower composite risk of 30-day mortality and stroke (OR 0.38). Female sex (OR 4.71), lower extremity ischaemia at presentation (OR 3.07), and CPB >235 minutes (OR 2.47), all portended worse postoperative outcomes.

CONCLUSIONS

A surgical strategy of MHCA is at least as safe as DHCA during repair of acute type A aortic dissection. ACP during HCA is associated with reduced 30-day mortality and stroke, whereas female sex, lower extremity ischaemia, and longer CPB times are all predictive of poorer short-term outcomes.

Risk Factors for High Blood Product Use in Patients with Stanford Type A Dissection

BACKGROUND

 Intraoperative and postoperative bleeding associated with allogeneic blood transfusion and reoperation is still a common and feared complication in patients undergoing surgery due to acute Type A Aortic Dissection (aTAAD). The aim of our study was to identify risk factors for higher transfusion rates.

METHODS

 In this retrospective single center study we evaluated pre -, intra-, and postoperative data of 121 patients with aTAAD. Depending on the median of received packed red blood cells (PRBCs), patients were divided into Group A (<8 PRBC, n = 53) and Group B (≥8 PRBC n = 68). Statistical analyses (descriptive statistics, univariable and multivariable logistic regression) were performed using SPSS software 25.0. Statistical significance was assumed at p-value <0.05.

RESULTS

 A total of 120 patients received a blood product during their perioperative course. Among others we identified age, hemorrhagic pericardial effusion, and dual antiplatelet therapy as preoperative risk factors, low rectal temperature as intraoperative risk factor and low body temperature, positive fluid balance, high lactate level and beginning development of acute renal failure as postoperative risk factors.

CONCLUSION

 Our study identifies several factors which predict a higher likelihood of bleeding and consecutive blood transfusion. Knowledge of these factors could influence the therapy to reduce transfusion requirements and lead to a targeted and more efficient use of coagulation products.

Temperatur- und Perfusionsmanagement bei akuter Typ-A-Aortendissektion

Die chirurgische Versorgung der akuten Typ-A-Aortendissektion erfuhr in den letzten Jahrzehnten v. a. im Hinblick auf das Perfusions- und Temperaturmanagement eine ständige Entwicklung. Neurologische Komplikationen sind die Hauptursache der postoperativen Morbidität und Mortalität. Die Verwendung einer Herz-Lungen-Maschine, des Kreislaufstillstands in tiefer Hypothermie, die temporäre Unterbrechung der zerebralen Perfusion oder Hypoperfusion des Gehirns und die Manipulation an der Aorta können zu neurologischen Schäden führen. Der Kreislaufstillstand in tiefer Hypothermie ermöglicht Eingriffe an der thorakalen Aorta, die für die Sanierung einer akuten Dissektion notwendig sein können. Dies hat allerdings Limitationen: Einerseits ist die Eingriffszeit begrenzt, andererseits führt die tiefe Hypothermie selbst zu Schäden. Experimentelle und klinische Studien konnten zeigen, dass der Grad der Hypothermie einen Einfluss auf die Komplikationsrate hat. Auch über den Nutzen der retrograden Hirnperfusion besteht noch Uneinigkeit. Das Konzept des Kreislaufstillstands mit zusätzlicher Hirnperfusion, besonders wenn der Grad der Hypothermie entsprechend der erwarteten Kreislaufstillstandzeit angepasst wird, erwies sich als sichere Methode. Es ermöglicht komplexe Eingriffe an der Aorta bei geringen Komplikationsraten und wird zunehmend als Standardverfahren bei der Versorgung der akuten Typ-A-Dissektion angewandt.

Moderate Versus Deep Hypothermia in Type A Acute Aortic Dissection Repair: Insights from the International Registry of Acute Aortic Dissection

BACKGROUND

The optimal strategy for cerebral protection during repair of type A acute aortic dissection has yet to be determined. We sought to determine the impact of differing degrees of hypothermia in patients undergoing acute dissection repair.

METHODS

All patients in the International Registry of Acute Aortic Dissection Interventional Cohort database who underwent type A acute aortic dissection repair between 2010 and 2018 were identified. Data for operative temperature were available for 1962 patients subsequently divided into 2 groups according to lowest temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). We then propensity matched 362 pairs of patients and analyzed operative data and short-term outcomes.

RESULTS

The median lowest temperature was 25.0°C in the matched MHCA group as compared with 18.0°C in the DHCA group. For the entire cohort of 1962 patients, in-hospital mortality was 14.2% (278 deaths) but was not significantly different between DHCA and MHCA. The perioperative stroke rate was comparable between groups, before and after propensity matching. Circulatory arrest times were significantly longer in the MHCA cohort, regardless of matching. Use of antegrade or retrograde cerebral perfusion was similar in matched groups. There were no differences in 30-day survival or in other major postoperative morbidity between the 2 matched cohorts.

CONCLUSIONS

A surgical strategy of MHCA + antegrade cerebral perfusion is at least as safe as DHCA during repair of acute type A aortic dissection.

Effect of Deep Hypothermic Circulatory Arrest Versus Moderate Hypothermic Circulatory Arrest in Aortic Arch Surgery on Postoperative Renal Function: A Systematic Review and Meta-Analysis

Background

Moderate hypothermic circulatory arrest (MHCA) has been widely used in aortic arch surgery. However, the renal function after MHCA remains controversial. We performed a systematic review and meta‐analysis direct comparison of the postoperative renal function of MHCA versus deep hypothermic circulatory arrest (DHCA) in aortic arch surgery.

Methods and Results

We searched PubMed, Embase, and the Cochrane Library for postoperative renal function after aortic arch surgery with using MHCA and DHCA, published from inception to January 31, 2020. The primary outcome was renal failure. Secondary outcomes were the need for renal therapy and other major postoperative outcomes. The random‐effects model was used for all comparisons to pool the estimates. A total of 14 observational studies with 4142 patients were included. Compared with DHCA, MHCA significantly reduced the incidence of renal failure (odds ratio [OR], 0.76; 95% CI, 0.61–0.94; P=0.011; I²=0.0%) and the need of renal replacement (OR, 0.68; 95% CI, 0.48–0.97; P=0.034; I²=0.0%). Subgroup analysis showed that when the hypothermic circulatory arrest time was <30 minutes, the incidence of renal failure in MHCA group was significantly lower than that in DHCA group (OR, 0.73; 95% CI, 0.54–0.99; P=0.040; I²=1.1%), whereas an insignificant difference between 2 groups when hypothermic circulatory arrest time was >30 minutes (OR, 0.76; 95% CI, 0.51–1.13; P=0.169; I²=17.3%).

Conclusions

MHCA compared with DHCA reduces the incidence of renal failure and the need for renal replacement.

Registration

URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42020169348.

Repair of Acute Type-A Aortic Dissection in the Present Era: Outcomes and Controversies

Acute Type-A aortic dissection (AAAD) remains a surgical emergency with a relatively high operative mortality despite advances in medical and surgical management over the past three decades. In spite of the severity of disease, there is a paucity of studies reviewing key controversies surrounding AAAD repair and management. A systematic literature search was performed using Cochrane review and PubMed bibliography review. Abstracts were first reviewed for general pertinence and then articles were reviewed in full. Literature review indicates that use of moderate hypothermia and antegrade cerebral perfusion is a safe alternative to deep hypothermia. In hemodynamically stable patients, axillary cannulation may be substituted for femoral cannulation. With regard to the technical aspects of repair, preserving the aortic root whenever possible and performing the distal anastomosis with the open distal technique rather than with the clamp on is the preferred approach. In patients with a patent false lumen, close monitoring is indicated. As demonstrated by the literature, significant improvement of early and late mortality over the past years has occurred in patients presenting with AAAD. Repair of acute Type-A aortic dissection remains a challenge with high operative mortality; however, improvement of surgical techniques and management have resulted in improvement of early and late clinical outcomes.

Moderate and deep hypothermic circulatory arrest has a comparable effect on acute kidney injury after total arch replacement with frozen elephant trunk procedure in type A aortic dissection

OBJECTIVES

The goal was to investigate the prevalence of acute kidney injury (AKI) after total arch replacement with frozen elephant trunk procedure, which was achieved by antegrade cerebral perfusion and moderate hypothermic circulatory arrest (MHCA) or deep hypothermic circulatory arrest (DHCA) among patients with type A aortic dissection.

METHODS

Overall, 627 adult type A aortic dissection patients who underwent total arch replacement with frozen elephant trunk from January 2013 until December 2016 at Fuwai Hospital were divided into the DHCA (14.1-20.0°C) and MHCA (20.1-28.0°C) groups. Postoperative AKI as the primary outcome was compared using propensity-matched scoring.

RESULTS

Overall, 340 (54.2%) and 287 (45.8%) patients underwent DHCA and MHCA, respectively. The overall incidence of AKI was 75.4%. Age [odds ratio (OR) 1.02, 95% confidence interval (CI) 1.00-1.04; P = 0.022], body mass index (OR 1.06, 95% CI 1.01-1.12; P = 0.016), cardiopulmonary bypass duration (OR 1.01, 95% CI 1.00-1.01; P = 0.003) and hypertension history (OR 1.76, 95% CI 1.14-2.70; P = 0.010) were identified as independent risk factors for AKI onset with multivariable analysis. Postoperative AKI was not significantly different between the DHCA and MHCA groups regardless of the overall or propensity-matched cohort (overall data: P = 0.17; propensity score data: P = 0.88). Patients with MHCA experienced higher rates of postoperative stroke after propensity score analysis (DHCA 0.9% vs MHCA 3.7%; P = 0.034).

CONCLUSIONS

MHCA was not superior to DHCA in decreasing postoperative AKI. Thus, MHCA should not definitively replace DHCA.