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

Cerebral Perfusion and Protection During Repair of Type A Dissection

Patients with the highest risk of neurologic injury after cardiac surgery are those undergoing repair of type A aortic dissections. Since the 1950s, extensive research has been conducted to improve the safety and neurologic outcomes of these patients. Surgeons now routinely use hypothermia with circulatory arrest, and adjunctive cerebral perfusion methods. This article highlights the historic development of modern cerebral perfusion and protection, and discusses technical details and clinical outcomes of cannulation strategies, temperature management, and antegrade cerebral perfusion and retrograde cerebral perfusion.

Anesthetic Management for Proximal Aortic Repair

Surgical repair of the proximal aorta is a complex endeavor, requiring cardiopulmonary bypass (CPB) and often the use of hypothermic circulatory arrest (HCA). In addition to the normal considerations for patients undergoing cardiopulmonary bypass, additional challenges include cerebral and end-organ protection during periods of circulatory arrest. This review aims to provide an up-to-date, evidence-based review on anesthetic management for proximal aortic repair.

Impact of mild hypothermic circulatory arrest on surgical outcomes in acute type a aortic dissection patients: a single-centre study

BACKGROUND

As hypothermic circulatory arrest (HCA) is being more frequently induced in patients undergoing aortic arch surgery, its safety at different degrees has become a crucial area of study. The aim of this study was to assess the surgical outcomes of mild hypothermic circulatory arrest (MI-HCA) during aortic arch surgery.

METHODS

Acute type A aortic dissection (ATAAD) patients who underwent total arch replacement (TAR) and frozen elephant trunk (FET) surgery between January 2014 and December 2023 were enrolled in this study. The patients were divided into two groups according to the minimum nasopharyngeal temperature: the moderate hypothermic circulatory arrest (MHCA) group (20-28 °C) and the MI-HCA group (> 28 °C). The inverse probability of treatment weighting (IPTW) was used to balance differences in the baseline characteristics. Perioperative variables were analysed via pairwise comparisons, multivariable logistic regression, and subgroup forest plots to assess the impact of MI-HCA on surgical outcomes.

RESULTS

A total of 447 patients were included in this study, and the mean minimum nasopharyngeal temperature was 24.80 (23.98, 27.30) °C in the MHCA group and 30.10 (29.80, 30.70) °C in the MI-HCA group. The incidence of acute kidney injury (AKI) in the MI-HCA group was lower than that in the MHCA group (52% vs. 78%, p < 0.01). In the multivariable logistic regression analysis, MI-HCA was identified as an independent protective factor for AKI (OR = 0.354, 95% CI 0.177-0.689; p = 0.003). Additionally, compared with MHCA, MI-HCA was not associated with an increased incidence of stroke, spinal cord injury, or in-hospital mortality. After IPTW, the preoperative and intraoperative data of the patients were balanced, and the incidence of AKI in the MI-HCA group was still lower than that in the MHCA group (83.26% vs. 53.61%, p = 0.004). The subgroup forest plot also demonstrated that MI-HCA was a protective factor for postoperative AKI.

CONCLUSIONS

The surgical outcomes of MI-HCA in ATAAD patients were satisfactory. Compared with MHCA, MI-HCA provided sufficient protection for distal organs, the brain, and the spinal cord, with a significantly lower incidence of AKI. These results indicate that MI-HCA could be a better approach for ATAAD surgery.

Aortic lumen repair with glue-felt technique before proximal anastomosis in acute type a aortic dissection surgery

OBJECTIVES

Despite the advances in medicine, aortic dissection remains a cardiac surgery emergency with high mortality and morbidity rates. This study examined the effects of the Glue + Felt technique, which uses biological glue and felt to repair the proximal anastomotic site, on the outcomes of patients with acute type A aortic dissection.

METHODS

A total of 108 patients who underwent surgery for acute type A aortic dissection at our clinic between 2007 and 2020 were included in the study. The patients were divided into two groups: the "Glue + Felt Technique" and the "Bentall-De Bono" groups, based on the surgical technique used for the aortic root. The effects of these two techniques on the development of intraoperative and postoperative complications and survival rates were statistically analyzed.

RESULTS

The Glue + Felt technique was used for 76 patients, while the Bentall-De Bono technique was used for 32 patients. The Kaplan-Meier analysis revealed significant differences in survival rates between the two groups over the entire follow-up period, both with and without propensity score matching (p < 0.001 and p = 0.02, respectively). However, no significant differences were observed in comparisons beyond the first 30 days of follow-up, either with or without propensity score matching (p = 0.573 and p = 0.561, respectively). The main factors contributing to this difference were the duration of cardiopulmonary bypass and aortic cross-clamp time (p < 0.05). During the average follow-up period of 46.2 ± 31.6 months, no re-intervention was required in patients from the Glue-Felt technique group.

CONCLUSIONS

The mortality rate in aortic dissection surgery is higher with more extensive surgical intervention as the duration of cardiopulmonary bypass and aortic cross-clamp time increases. Repairing the lumen and reducing operation time in suitable patients using the Glue-Felt technique for the proximal anastomotic site positively impacts postoperative complications and improves in-hospital and 30-day survival rates, without increasing long-term re-intervention rates.

Optimal circulatory arrest temperature for total aortic arch replacement: Outcomes of neurological complications

OBJECTIVE

The optimal hypothermic circulatory arrest temperature during total arch replacement and the impact of hypothermic circulatory arrest temperature on postoperative neurological complications are still uncertain. The aim of this study is to explore the impact of hypothermic circulatory arrest temperature on short-term postoperative outcomes, especially neurological complications, for patients who undergo total arch replacement.

METHODS

We retrospectively analyzed data of 2351 patients who underwent total arch replacement at 1 of 7 selected aortic centers from January 2016 to June 2023. Restricted cubic splines and subgroup analyses were performed to determine the relation between temperature and outcomes under different cerebral perfusion methods, cannulation strategies, diagnoses, and surgical timings.

RESULTS

The overall in-hospital mortality was 6.2% (n = 146). The incidence of stroke, paraplegia, and total-arch composite outcome was 6.0% (n = 142), 2.8% (n = 65), and 21.0% (n = 494), respectively. The average hypothermic circulatory arrest temperature was 25.9 °C ± 1.9 °C, and the median circulatory arrest time was 23 minutes (Q1, Q3: 18, 30). Adjusted restricted cubic splines showed the lowest incidence of stroke, paraplegia, and total-arch composite outcome at temperatures of 26.6 °C, 27.4 °C, and 26.8 °C, respectively, but without statistical significance. In subgroup analysis, the unilateral antegrade cerebral perfusion group revealed a significant nonlinear relation between the hypothermic circulatory arrest temperature and the risk of stroke, and the lowest risk was at 26.5 °C. Other subgroup analyses did not reveal a significant nonlinear relation between temperature and outcomes.

CONCLUSIONS

For patients undergoing total arch replacement with unilateral antegrade cerebral perfusion, cooling to a temperature of 26 °C to 27 °C was associated with the lowest incidence of stroke.

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.

Moderate hypothermia circulatory arrest as a brain-protective strategy for type A aortic dissection

OBJECTIVES

Brain-protective strategies for acute type A aortic dissection (TAAD) remain controversial. Moderate hypothermia circulatory arrest (MHCA) without cerebral perfusion is not commonly used. However, we aimed to assess its safety and efficacy in 358 patients who underwent hemiarch replacement with MHCA for acute type A aortic dissection at our institution from August 2012 to August 2022.

METHODS

Clinical outcomes were compared according to circulatory arrest time [≤15 min (S group, n = 52) vs ≥16 min (L group, n = 306)]. The primary outcome was postoperative stroke.

RESULTS

The S group had more older patients (72.5 vs 68.8 years; P = 0.04), a greater incidence of carotid artery malperfusion (21% vs 11%; P = 0.043) and a lower body mass index (21.7 vs 23.6 kg/m2; P < 0.01) and hemodynamic instability (3.8% vs 16%; P = 0.02) than the L group. The incidence of postoperative stroke (7.7% vs 12%; P = 0.33) and the rate of 30-day mortality (5.8% vs 6.5%; P = 0.83) did not significantly differ between groups. After adjusting for all potential confounding factors pre- and intraoperatively, there was no significant difference in postoperative outcomes between groups.

CONCLUSIONS

MHCA alone for TAAD had comparable postoperative outcomes with circulatory arrest times under and over 15 min. However, longer arrest times were associated with a higher risk of stroke.

Cardiopulmonary resuscitation at operating room entry in acute aortic dissection type A patients: is surgery contraindicated?

Background

This study aimed to compare the short-term outcomes of surgical treatment for acute type A aortic dissection between patients undergoing cardiopulmonary arrest at the time of entry into the operating room and patients who received successful preoperative cardiopulmonary resuscitation before entering the operating room or patients who had cardiopulmonary arrest on the operating room table after entering the operating room without cardiopulmonary arrest. In the present study, we focused on the circulatory status at the time of entering the operating room because it is economically and emotionally difficult to cease intervention once the patient has entered the operating room, where surgeons, anesthesiologists, nurses, and perfusionists are already present, all necessary materials are packed off and cardiopulmonary bypass have already been primed.

Methods

Twenty (5.5%) of 362 patients who underwent surgical treatment for acute type A aortic dissection between January 2016 and March 2022 had preoperative cardiopulmonary arrest. To compare the early operative outcomes, the patients were divided into the spontaneous circulation group (n = 14, 70.0%) and the non-spontaneous circulation group (n = 6, 30.0%) based on the presence or absence of spontaneous circulation upon entering the operating room. The primary endpoint was postoperative 30-day mortality. The secondary endpoints included in-hospital complications and persistent neurological disorders.

Results

Thirty-day mortality was 65% (n = 13/20) in the entire cohort; 50% (n = 7/14) in the spontaneous circulation group and 100% (n = 6/6) in the non-spontaneous circulation group. The major cardiopulmonary arrest causes were aortic rupture and cardiac tamponade (n = 16; 80.0%), followed by coronary malperfusion (n = 4; 20.0%). Seven patients (50.0%) survived in the spontaneous circulation group, and none survived in the non-spontaneous circulation group (P = .044). Five survivors walked unaided and were discharged home; the remaining two were comatose and paraplegic.

Conclusions

The outcomes were extremely poor in patients with acute type A aortic dissection who had preoperative cardiopulmonary arrest and received ongoing cardiopulmonary resuscitation at entry into the operating room. Therefore, surgical treatment might be contraindicated in such patients.

Serum NPTX2 as a Potential Predictive Biomarker for Postoperative Delirium in Patients with Acute Type A Aortic Dissection

Background

Postoperative delirium (POD) significantly impacts patient outcomes after acute type A aortic dissection (ATAAD) surgeries. This study investigates the role of Neuronal Pentraxin 2 (NPTX2) as a potential biomarker for POD in ATAAD patients.

Methods

This secondary analysis involved ATAAD patients from a prospective observational study. Serum NPTX2 levels were measured preoperatively and immediately postoperatively using Enzyme-Linked Immunosorbent Assay (ELISA). Delirium was assessed using the Confusion Assessment Method (CAM) or CAM for the ICU (CAM-ICU). Statistical analyses included the Pearson Correlation Coefficient and multivariate logistic regression to evaluate the association between NPTX2 levels and POD.

Results

Among the 62 patients included, 46.77% developed POD. Patients with POD had significantly lower preoperative and postoperative serum NPTX2 levels. The Receiver Operating Characteristic (ROC) curve analysis showed that postoperative NPTX2 had a strong predictive capability for POD (AUC = 0.895). The optimal cutoff for postoperative NPTX2 in predicting POD was less than 421.4 pg/mL. Preoperative NPTX2 also demonstrated predictive value, albeit weaker (AUC = 0.683).

Conclusion

Serum NPTX2 levels, both preoperatively and postoperatively, are promising biomarkers for predicting POD in ATAAD patients. These findings suggest that NPTX2 could be instrumental in early POD detection and intervention strategies.

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.

Histopathological Gap in Aortic Diseases: A Prospective Analysis

Aortic dissection (AD) is a critical cardiovascular condition with the potential for devastating consequences. This study evaluated the histological changes in the aorta wall in patients with AD and aortic aneurysm (AA) who received surgical aortic replacement. Histopathological data showed that modifications of the media layer (p = 0.0197), myxomatous aspect (p = 0.0001), and subendothelial layer degeneration (p = 0.0107) were more frequently seen in AA versus AD samples. Patients with AA were approximately twice as likely to develop histological changes than those with AD (p = 0.0037). Patients with moderate or severe medial degeneration had a higher chance of developing AD (p = 0.0001). Because the histopathological score proved to be a predictor of both in-hospital and overall mortality, its evaluation should become the standard of care in any patients who undergo aortic replacement. Individualized postoperative management might be influenced by the histopathological aspect of the aortic layer.

Early results of frozen elephant trunk in acute type-A dissection in 1445 patients

BACKGROUND

We aimed to briefly describe the use of total arch replacement with frozen elephant trunk in our center's 12-year treatment of acute type A dissection and the early postoperative results. We summarized the practical experience of this procedure in our center and performed regression analyses to find the independent risk factors for major complications.

METHODS

Consecutive patients with acute type A dissection having surgical total arch replacement with the implantation of a frozen elephant trunk were collected from January 2010 to December 2021 and were included in the analysis. For each major operation-related complication, independent risk factors were identified using both univariate and multivariate regression models.

RESULTS

In our institution, the total arch replacement with frozen elephant trunk procedure is used more frequently each year and makes up 70% of the surgical procedures for acute type A dissection. The overall postoperative mortality rate was 6.2%, which declined as the techniques (including surgical procedures, organ perfusion protection etc.) improved. Other complications include: 11.7% for continuous renal replacement therapy, 5.7% for stroke, 17.8% for ICU stay longer than 7 days, 10.9% for prolonged mechanical ventilation, and so on. According to regression analysis, different major complications had different independent risk factors. Several factors, such as advanced age, impaired renal function, and extended cardiopulmonary bypass time, were found to be implicated in nearly all of the complications.

CONCLUSION

Total arch replacement plus frozen elephant trunk strategy is a safe surgical method for extensive acute type A dissection. Some factors, such as advanced age, impaired renal function, and prolonged cardiopulmonary bypass time, might be associated with poor prognosis.

Cerebral Protection Strategies and Stroke in Surgery for Acute Type A Aortic Dissection

Background: Perioperative stroke remains a devastating complication in the operative treatment of acute type A aortic dissection. To reduce the risk of perioperative stroke, different perfusion techniques can be applied. A consensus on the preferred cerebral protection strategy does not exist. Methods: To provide an overview about the different cerebral protection strategies, literature research on Medline/PubMed was performed. All available original articles reporting on cerebral protection in surgery for acute type A aortic dissection and neurologic outcomes since 2010 were included. Results: Antegrade and retrograde cerebral perfusion may provide similar neurological outcomes while outperforming deep hypothermic circulatory arrest. The choice of arterial cannulation site and chosen level of hypothermia are influencing factors for perioperative stroke. Conclusions: Deep hypothermic circulatory arrest is not recommended as the sole cerebral protection technique. Antegrade and retrograde cerebral perfusion are today’s standard to provide cerebral protection during aortic surgery. Bilateral antegrade cerebral perfusion potentially leads to superior outcomes during prolonged circulatory arrest times between 30 and 50 min. Arterial cannulation sites with antegrade perfusion (axillary, central or carotid artery) in combination with moderate hypothermia seem to be advantageous. Every concept should be complemented by adequate intraoperative neuromonitoring.

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.

Optimal temperature management in aortic arch surgery: A systematic review and network meta-analysis

OBJECTIVES

New temperature management concepts of moderate and mild hypothermic circulatory arrest during aortic arch surgery have gained weight over profound cooling. Comparisons of all temperature levels have rarely been performed. We performed direct and indirect comparisons of deep hypothermic circulatory arrest (DHCA) (≤20°C), moderate hypothermic circulatory arrest (MHCA) (20.1-25°C), and mild hypothermic circulatory arrest (mild HCA) (≥25.1°C) in a network meta-analysis.

METHODS

The literature was systematically searched for all papers published through February 2022 reporting on clinical outcomes after aortic arch surgery utilizing DHCA, MHCA and mild HCA. The primary outcome was operative mortality. The secondary outcomes were postoperative stroke and acute kidney failure (AKI).

RESULTS

A total of 34 studies were included, with a total of 12,370 patients. DHCA was associated with significantly higher postoperative incidence of stroke when compared with MHCA (odds ratio [OR], 1.46, 95% confidence interval [CI], 1.19-1.78) and mild HCA: (OR, 1.50, 95% CI, 1.14-1.98). Furthermore, DHCA and MHCA were associated with higher operative mortality when compared with mild HCA (OR 1.71, 95% CI, 1.23-2.39 and OR 1.50, 95% CI, 1.12-2.00, respectively). Separate analysis of randomized and propensity score matched studies showed sustained increased risk of stroke with DHCA in contrast to MHCA and mild HCA (OR, 1.61, 95% CI, 1.18-2.20, p value = .0029 and OR, 1.74, 95% CI, 1.09-2.77, p value = .019).

CONCLUSIONS

In the included studies, the moderate to mild hypothermia strategies were associated with decreased operative mortality and the risk of postoperative stroke. Large-scale prospective studies are warranted to further explore appropriate temperature management for the treatment of aortic arch pathologies.

Left Subclavian Artery Sacrifice in Acute Aortic Dissection Repair using the Frozen Elephant Trunk

OBJECTIVE

Surgery of acute aortic dissection using the frozen elephant trunk (FET) can be complicated when the origin of the left subclavian artery (LSA) is dissected and sacrifice by ligation is a viable option. However, the LSA is supposed to play a role in neuroprotection as a major collateral. We, therefore, analyzed our results of LSA sacrifice in this cohort.

METHODS

We identified a total of 84 patients from our prospectively collected database who underwent FET repair of acute aortic dissection between October 2009 and April 2018. LSA was sacrificed in 19 patients (22.6%). Results were analyzed and compared with regard to neurological outcomes.

RESULTS

New postoperative stroke was seen in two patients (2.4%) and spinal cord injury in three patients (3.6%) overall, none in the LSA-sacrifice group. We observed a temporary neurological deficit in five patients (6.0%) overall, none in the LSA-sacrifice group. None of the patients developed acute ischemia of the left arm. Only two patients (12.5%) came back for carotid-subclavian artery bypass due to exertion-induced weakness of the left arm 3 to 4 months after the initial surgery. In-hospital mortality was 15.5% overall, with no difference between groups.

CONCLUSION

LSA sacrifice was not associated with elevated postoperative risk of either central or spinal neurological injury. Thus, it can facilitate FET repair of acute aortic dissection in selected cases when the left subclavian origin cannot be preserved. Carotid-subclavian artery bypass became necessary in only a small fraction of these patients and can be performed as a second-stage procedure.

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.

Association of dissected ascending aorta diameter with preoperative adverse events in patients with acute type A aortic dissection

BACKGROUND

Acute type A aortic dissection (ATAAD) is a life-threatening disease associated with high morbidity and mortality.

AIM

To evaluate the diameter of dissected ascending aorta in patients diagnosed with ATAAD and whether the aortic diameter is associated with preoperative adverse events.

METHODS

A total of 108 patients diagnosed with ATAAD who underwent emergency operation under hypothermic circulatory arrest were enrolled in this study. Demographic characteristics and perioperative data were recorded. In all patients, preoperative chest and abdomen computed tomography (CT) scans were performed.

RESULTS

Median age of the patients was 61.5 (52.5-70.5) years and median body mass index (BMI) was 28.2 (25.1-32.6) cm2. The number of female patients was 37 (25%). Median diameter of the ascending aorta was 5.0 (4.5-6) cm and 53.8% of the patients had an aortic diameter < 5.0 cm, while 32.3% of the patients had an aortic diameter of 4.5cm and 72.0% had an ascending aorta diameter < 5.5 cm. The diameter of the ascending aorta did not differ in patients with vs without preoperative adverse events: Preoperative neurological dysfunction (P = 0.53) and hemodynamic instability (P = 0.43). Median age of patients with preoperative hemodynamic instability was 65 (57.5-74) years, while it was 60 (51-68) years in patients without (P = 0.04).

CONCLUSION

Although current guidelines suggest replacing the ascending aorta with a diameter > 5.5 cm, most of the patients with ATAAD had an aortic diameter of less than 5.5 cm. The diameter of the ascending aorta in patients diagnose with ATAAD is not associated with preoperative adverse events.

Optimal circulatory arrest temperature for aortic hemiarch replacement with antegrade brain perfusion

OBJECTIVE

This study sought to identify the optimal temperature for moderate hypothermic circulatory arrest in patients undergoing elective hemiarch replacement with antegrade brain perfusion.

METHODS

The Society of Thoracic Surgeons adult cardiac surgery database was queried for elective hemiarch replacements using antegrade brain perfusion for aneurysmal disease (2014-2019). Generalized estimating equations and restricted cubic splines were used to determine the risk-adjusted relationships between temperature as a continuous variable and outcomes.

RESULTS

Elective hemiarch replacement with antegrade brain perfusion occurred in 3898 patients at 374 centers with a median nadir temperature of 24.9 °C (first quartile, third quartile = 22.0 °C, 27.5 °C) and median circulatory arrest time of 19 minutes (first quartile, third quartile = 14.0 minutes, 27.0 minutes). After adjustment for comorbidities, circulatory arrest time, and individual surgeon, patients cooled between 25 and 28 °C had an early survival advantage compared with 24 °C, whereas those cooled between 21 and 23 °C had higher risks of mortality compared with 24 °C. A nadir temperature of 27 °C was associated with the lowest risk-adjusted odds of mortality (odds ratio, 0.62; 95% confidence interval, 0.42-0.91). A nadir temperature of 21 °C had the highest risk of mortality (odds ratio, 1.4; 95% confidence interval, 1.13-1.73). Risk of experiencing a major morbidity was elevated in patients cooled between 21 and 23 °C, with the highest risk occurring in patients cooled to 21 °C (odds ratio, 1.12; 95% confidence interval, 1.01-1.24).

CONCLUSIONS

For patients with aneurysmal disease undergoing elective hemiarch with antegrade brain perfusion, circulatory arrest with a nadir temperature of 27 °C confers the greatest early survival benefit and smallest risk of postoperative morbidity.