Moderate Versus Deep Hypothermic Circulatory Arrest for Elective Aortic Transverse Hemiarch Reconstruction

Does Higher Temperature during Moderate Hypothermic Circulatory Arrest Increase the Risk of Paraplegia in Acute DeBakey I Aortic Dissection Patients?

BACKGROUND

To assess the safety of high-moderate (24.1-28.0°C) and low-moderate (20.1-24.0°C) systemic hypothermia (MHCA) during circulatory arrest in patients with acute DeBakey I aortic dissection (DeBakey I AAD), particularly concerning spinal cord protection.

METHODS

Between 2009 and 2020, 1759 patients with DeBakey I AAD who underwent frozen elephant trunk and total arch replacement surgery at a tertiary center were divided into preoperative malperfusion (viscera, spinal cord, or lower extremities) and non-malperfusion subgroups. The baseline differences were balanced using propensity score matching. Prognoses were compared between those who were subjected to high-MHCA (nasopharyngeal temperature, 24.1-28.0°C) and low-MHCA (20.1-24.0°C).

RESULTS

In the non-malperfusion subgroup (n=1389), 469 pairs of matched patients showed lower in-hospital mortality and incidence of acute kidney injury in the high-MHCA group than in the low-MHCA group (in-hospital mortality, 7.0% vs. 10.2%, P=0.01; acute kidney injury, 57.1% vs. 64.6%, P<0.01). The duration of mechanical ventilation was shorter in the high-MHCA group than that in the low-MHCA group (P=0.03). No significant difference in the incidence of paraplegia was observed between the two groups. In the malperfusion subgroup (n=370), 112 pairs of matched patients showed a higher incidence of paraplegia in the high-MHCA group than in the low-MHCA group (15.9% vs. 6.5%, P=0.04).

CONCLUSIONS

The safety of high-MHCA, a commonly used temperature management strategy during aortic arch surgery, was recognized in most patients with DeBakey I AAD. However, among patients with preoperative distal organ malperfusion, low-MHCA may be more appropriate because of an increased risk of postoperative paraplegia associated with high-MHCA.

Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest Trial (GOT ICE): A Randomized Clinical Trial Comparing Outcomes After Aortic Arch Surgery

BACKGROUND

Deep hypothermia has been the standard for hypothermic circulatory arrest (HCA) during aortic arch surgery. However, centers worldwide have shifted toward lesser hypothermia with antegrade cerebral perfusion. This has been supported by retrospective data, but there has yet to be a multicenter, prospective randomized study comparing deep versus moderate hypothermia during HCA.

METHODS

This was a randomized single-blind trial (GOT ICE [Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest]) of patients undergoing arch surgery with HCA plus antegrade cerebral perfusion at 4 US referral aortic centers (August 2016-December 2021). Patients were randomized to 1 of 3 hypothermia groups: DP, deep (≤20.0 °C); LM, low-moderate (20.1-24.0 °C); and HM, high-moderate (24.1-28.0 °C). The primary outcome was composite global cognitive change score between baseline and 4 weeks postoperatively. Analysis followed the intention-to-treat principle to evaluate if: (1) LM noninferior to DP on global cognitive change score; (2) DP superior to HM. The secondary outcomes were domain-specific cognitive change scores, neuroimaging findings, quality of life, and adverse events.

RESULTS

A total of 308 patients consented; 282 met inclusion and were randomized. A total of 273 completed surgery, and 251 completed the 4-week follow-up (DP, 85 [34%]; LM, 80 [34%]; HM, 86 [34%]). Mean global cognitive change score from baseline to 4 weeks in the LM group was noninferior to the DP group; likewise, no significant difference was observed between DP and HM. Noninferiority of LM versus DP, and lack of difference between DP and HM, remained for domain-specific cognitive change scores, except structured verbal memory, with noninferiority of LM versus DP not established and structured verbal memory better preserved in DP versus HM (P = 0.036). There were no significant differences in structural or functional magnetic resonance imaging brain imaging between groups postoperatively. Regardless of temperature, patients who underwent HCA demonstrated significant reductions in cerebral gray matter volume, cortical thickness, and regional brain functional connectivity. Thirty-day in-hospital mortality, major morbidity, and quality of life were not different between groups.

CONCLUSIONS

This randomized multicenter study evaluating arch surgery HCA temperature strategies found low-moderate hypothermia noninferior to traditional deep hypothermia on global cognitive change 4 weeks after surgery, although in secondary analysis, structured verbal memory was better preserved in the deep group. The verbal memory differences in the low- and high-moderate groups and structural and functional connectivity reductions from baseline merit further investigation and suggest opportunities to further optimize brain perfusion during HCA.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02834065.

Cavoatrial hypernephroma resection on cardiopulmonary bypass: Mild/normo-versus moderate hypothermia

INTRODUCION

Renal cell carcinoma (RCC) is one of the most prevalent malignant tumors. It extends up into the systemic veins and right atrium. Surgical extraction of such extensions is usually carried out using cardiopulmonary bypass (CPB) with moderate hypothermic (MH) being frequently applied in order to obtain a clear surgical field. However, due to obvious disadvantages of hypothermia, approaches with mild/normothermia (NT) during CPB have also been established. The current study aims to compare the outcomes of patients undergoing RCC tumor and extensions resection using MH versus NT.

MATERIAL AND METHODS

This is a retrospective, non-randomized study. All patients who underwent RCC tumor and extensions resection for stage III or IV (Staehler) RCC in a single center between 2006 and 2020 were included. During surgery, MH or NT were applied. CPB was realized using aortic and bicaval cannulation. We compared the procedural times, transfusion requirements and postoperative outcomes, respectively between the MH and NT groups.

RESULTS

A total of 24 consecutive patients (n(NT) = 12, n(MH) = 12) were included in the study (median age NT 68.5 and MH 66.5). The study only showed a significant difference in heart-lung machine times (median CPB time NT 45.5 min and MH 110.0 min, p = 0.004). All other results, loss of drainage, administration of blood products, as well as the postoperative course and mortality were comparable in both groups.

CONCLUSION

The results showed a high perioperative and long-term mortality. The perioperative course was similar after surgery with NT or MH. Therefore, NT which minimizes potential complications of MH should be preferred.

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.

Hybrid Treatment of Complex Diseases of the Aortic Arch and Descending Thoracic Aorta by Frozen Elephant Trunk Technique

The surgical management of acute and chronic complex diseases involving the aortic arch and the descending thoracic aorta remains challenging. Hybrid procedures associating total open arch replacement and stent-grafting of the proximal descending aorta were developed to allow a potential single-stage treatment, promote remodeling of the downstream aorta, and facilitate a potential second-stage thoracic endovascular aortic repair by providing an ideal landing zone. While these approaches initially used various homemade combinations of available conventional prostheses and stent-grafts, the so-called frozen elephant trunk technique emerged with the development of several custom-made hybrid prostheses. The aim of this study was to review the contemporary outcomes of this technique in the management of complex aortic diseases, with a special focus on procedural planning, organ protection and monitoring, refinements in surgical techniques, and long-term follow-up.

Cardiopulmonary bypass for total aortic arch replacement surgery: A review of three techniques

One treatment for acute type A aortic dissection is to replace the ascending aorta and aortic arch with a graft during circulatory arrest of the lower body, but this is associated with high mortality and morbidity. Maintaining the balance between oxygen supply and demand during circulatory arrest is the key to reducing morbidity and is the primary challenge during body perfusion. The aim of this review is to summarize current knowledge of body perfusion techniques and to predict future development of this field. We present three perfusion techniques based on deep hypothermic circulatory arrest (DHCA): DHCA alone, DHCA with selective cerebral perfusion, and DHCA with total body perfusion. DHCA was first developed to provide a clear surgical field, but it may contribute to stroke in 4%–15% of patients. Antegrade or retrograde cerebral perfusion can provide blood flow for the brain during circulatory arrest, and it is associated with much lower stroke incidence of 3%–9%. Antegrade cerebral perfusion may be better than retrograde perfusion during longer arrest. In theory, blood flow can be provided to all vital organs through total body perfusion, which can be implemented via either arterial or venous systems, or by combining retrograde inferior vena caval perfusion with antegrade cerebral perfusion. However, whether total body perfusion is better than other techniques require further investigation in large, multicenter studies. Current techniques for perfusion during circulatory arrest remain imperfect, and a technique that effectively perfuses the upper and lower body effectively during circulatory arrest is missing. Total body perfusion should be systematically compared against selective cerebral perfusion for improving outcomes after circulatory arrest.

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.

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.

Contemporary utilization of the axillary artery in cardiac surgery

INTRODUCTION

The axillary artery is a reliable inflow vessel when addressing pathology of the aortic root and aortic arch that may preclude standard central cannulation strategies. This narrative review examines the use of the axillary artery in cardiac surgery. Anatomy, indications for use, cannulation strategies, and potential complications will be discussed.

METHODS

A comprehensive review of the current literature was performed using PubMed, Cochrane Review, and authoritative committee guidelines. A narrative review incorporating current available evidence was undertaken.

COMMENT

Use of the axillary artery in select cardiac surgical cases is reliable, reproducible, and may be preferable in certain cases involving ascending aortic pathology, reoperative surgery, porcelain aorta, access for transcatheter valve therapies, and peripheral mechanical circulatory support.

A case report of an unusual mycotic pseudoaneurysm of the ascending aorta

Background

Mycotic pseudoaneurysms of the ascending aorta are a rare and devastating complication of previous cardiac surgery.

Case presentation

We present an unusual case of a fungal mycotic pseudoaneurysm secondary to an aortic suture line successfully repaired under deep hypothermic circulatory arrest.

Conclusions

Patients with mycotic pseudoaneurysms of the aorta require a multidisciplinary team approach to prevent devastating complications that may occur in these complex surgical cases.

Duration of deep hypothermic circulatory arrest for aortic arch surgery: is it a myth, fiction, or scientific leap?

INTRODUCTION

The use of deep hypothermic circulatory arrest (DHCA) to provide aortic surgeons with a bloodless operative field while simultaneously protecting the brain and peripheries from ischemic damage revolutionized cardiac and aortic surgery, and is currently used in specialist centers across the globe. However, it is associated with manifold adverse outcomes, including neurocognitive dysfunction and mortality. This review seeks to analyze the relationship between DHCA duration and clinical outcome, and evaluate the controversies and limitations surrounding its use.

EVIDENCE ACQUISITION

We performed a review of available literature with statistical analysis to evaluate the relationship between DHCA duration (<40 min and >40 min) and key clinical outcomes, including mortality, permanent and temporary neurological deficit, renal damage, admission length, and reintervention rate. The controversies surrounding DHCA use and future directions for care are also explored.

EVIDENCE SYNTHESIS

Statistical analysis revealed no significant association (P>0.05) between DHCA duration and clinical outcomes (early and late mortality rates, neurological deficit, admission length, and reintervention rate), both with and without adjunctive perfusion techniques.

CONCLUSIONS

Available literature suggests that the relationships between DHCA duration (with and without adjunctive perfusion) and clinical outcomes are unclear, and at present not statistically significant. Alternative surgical and endovascular techniques have been identified as promising novel approaches not requiring DHCA, as have the use of biomarkers to enable early diagnosis and intervention for aortic pathologies.

Direct Innominate Artery Cannulation versus Side Graft for Selective Antegrade Cerebral Perfusion during Aortic Hemiarch Replacement

Background  Selective antegrade cerebral perfusion (SACP) has become our preferred method for cerebral protection during open arch cases. While the initial approach involved sewing a graft to the innominate artery as the arterial cannulation site, our access strategy has since evolved to central aortic cannulation with use of a percutaneous cannula in the innominate for SACP. We hypothesized that SACP delivered via direct innominate cannulation using a 12- or 14-Fr cannula results in equivalent outcomes to cases utilizing a side graft.

Methods  This was a single-center, retrospective analysis of 211 adult patients who underwent elective hemiarch replacement using hypothermic circulatory arrest with SACP via the innominate artery between 2012 and 2020. Urgent and emergent cases were excluded.

Results  A side graft sutured to the innominate was utilized in 81% ( n  = 171) of patients, while direct innominate artery cannulation was performed in 19% ( n  = 40) of patients. Baseline patient characteristics were similar between groups aside from a higher baseline creatinine in the direct cannulation group (1.3 vs. 0.9, p  = 0.032). Patients undergoing direct cannulation demonstrated shorter cardiopulmonary bypass time (132.7 vs. 154.9 minutes, p  = 0.020) and shorter circulatory arrest time (8.1 vs. 10.9 minutes, p  = 0.004). Nadir bladder temperature did not significantly differ between groups (27.2°C for side graft vs. 27.6°C for direct cannulation, p  = 0.088). There were no significant differences in postoperative outcomes.

Conclusion  Direct cannulation of the innominate artery with a 12- or 14-Fr cannula for SACP during hemiarch replacement is a safe alternative to using a sutured side graft. While cardiopulmonary bypass and circulatory arrest times appear improved, this is likely attributable to accumulation of experience and proficiency in technique. However, direct innominate artery cannulation may facilitate quicker completion of these procedures by eliminating the time necessary to suture a graft to the innominate artery.

Neuroprotective strategies with circulatory arrest in open aortic surgery - A meta-analysis

Objective

Deep hypothermic circulatory arrest (DHCA) in aortic surgery is associated with morbidity and mortality despite evolving strategies. With the advent of antegrade cerebral perfusion (ACP), moderate hypothermic circulatory arrest (MHCA) was reported to have better outcomes than DHCA. There is no standardised guideline or consensus regarding the hypothermic strategies to be employed in open aortic surgery. Meta-analysis was performed comparing DHCA with MHCA + ACP in patients having aortic surgery.

Methods

A systematic review of the literature was undertaken. Any studies with DHCA versus MHCA + ACP in aortic surgeries were selected according to specific inclusion criteria and analysed to generate summative data. Statistical analysis was performed using STATS Direct. The primary outcomes were hospital mortality and post-operative stroke. Secondary outcomes were cardiopulmonary bypass time (CPB), post-operative blood transfusion, length of ICU stay, respiratory complications, renal failure and length of hospital stay. Subgroup analysis of primary outcomes for Arch surgery alone was also performed.

Results

Fifteen studies were included with a total of 5869 patients. There was significantly reduced mortality (Pooled OR = +0.64, 95% CI = +0.49 to +0.83; p = 0.0006) and stroke rate (Pooled OR = +0.62, 95% CI = +0.49 to +0.79; p < 0.001) in the MHCA group. MHCA was associated significantly with shorter CPB times, shorter duration in ICU, less pulmonary complications, and reduced rates of sepsis. There was no statistical difference between the two groups in terms of circulatory arrest times, X-Clamp times, total operation duration, transfusion requirements, renal failure and post-op hospital stay.

Conclusion

MHCA + ACP are associated with significantly better post-operative outcomes compared with DHCA for both mortality and stroke and majority of the secondary outcomes.

Evolving Surgical Techniques and Improving Outcomes for Aortic Arch Surgery in Canada

Background

To explore evolving surgical techniques and outcomes for aortic arch surgery.

Methods

A total of 2435 consecutive patients underwent aortic arch repair with hypothermic circulatory arrest between 2008 and 2018 in 12 institutions across Canada. Trends in patient characteristics, surgical techniques, and in-hospital outcomes, including major morbidity or mortality, were examined.

Results

From 2008 to 2018, the age of patients (62.3 ± 13.2 years) and the proportion of women (30.2%) undergoing arch surgery did not change significantly. Aortic diameters at operation decreased (2008: 58 ± 13 mm; 2018: 53 ± 11 mm; P < 0.01). Surgeons performed more valve-sparing root replacements (2008: 0%; 2018: 15%; P < 0.001) and fewer Bentall procedures (2008: 27%; 2018: 20%; P < 0.01). Total arch replacement rates were similar (P = 0.18); however, elephant trunk (2008: 9.5%; 2018: 19%; P < 0.001) and frozen elephant trunk (2008: 3.1%; 2018: 15%; P < 0.001) repair rates have increased. Over time, higher nadir temperatures (2008: 18 [17-21]°C; 2018: 25 [23-28]°C; P < 0.001), and more frequent antegrade cerebral perfusion (2008: 61%; 2018: 83%; P < 0.001) were used. For elective cases, in-hospital mortality rates declined (2008: 6.8%; 2018: 1.2%; P = < 0.01), as did major morbidity or mortality (2008: 24%; 2018: 13%; P < 0.001) and transfusion rates (2008: 61%; 2018: 41%; P < 0.001), but stroke rates remained constant (2008: 6.8%; 2018: 5.3%; P = 0.12). Outcomes remained the same over time for urgent or emergent cases.

Conclusions

Outcomes have improved over the past decade in Canada for elective aortic arch surgery, in the context of operating on smaller aortas, and more frequent use of moderate hypothermia and antegrade cerebral perfusion. Further research is needed to improve stroke rates and outcomes in the emergency setting.

Modified Technique for Retrograde Cerebral Perfusion during Hemiarch Aortic Replacement

Background  Uncertainty remains regarding the optimal method of brain protection for procedures that require repair or replacement of the aortic arch. We examined the early outcomes of a technique for brain protection in patients undergoing partial aortic arch (hemiarch) replacement that involves deep hypothermic circulatory arrest (DHCA) and retrograde cerebral perfusion (RCP) of cold blood from the superior vena cava toward the end of the arrest interval.

Methods  During a recent 15-year interval, 520 patients underwent elective or urgent/emergent ascending aortic and hemiarch replacement as an isolated (47 patients) or combined (473 patients) procedure employing DHCA (mean nasopharyngeal temperature at circulatory arrest, 17.1°C and mean duration, 19.3 minutes) supplemented with RCP of cold blood from the superior vena cava toward the end of the arrest interval (mean, 6.7 minutes). The mean age of the patients was 59.5 years, and 65% were male.

Results  The in-hospital and 30-day mortality rates were 1.2% (six patients). Seven patients (1.4%) sustained a stroke and 19 patients (3.7%) had transient neurologic dysfunction that completely resolved by the time of hospital discharge. Four patients (0.77%) developed postoperative renal failure requiring dialysis. Twenty-one patients (4%) required ventilator support for >48 hours and five patients (0.96%) required a tracheostomy. The median hospital length of stay was 6 days.

Conclusion  DHCA with a brief interval of RCP is a safe and effective technique for brain protection during hemiarch aortic replacement. RCP reduces the duration of brain ischemia and permits removal of particulate matter and air from the arterial circulation.

Does deeper hypothermia reduce the risk of acute kidney injury after circulatory arrest for aortic arch surgery?

OBJECTIVES

The impact of hypothermic circulatory arrest (HCA) temperature on postoperative acute kidney injury (AKI) has not been evaluated. This study examined the association between circulatory arrest temperatures and AKI in patients undergoing proximal aortic surgery with HCA.

METHODS

A total of 759 consecutive patients who underwent proximal aortic surgery (ascending ± valve ± root) including arch replacement requiring HCA between July 2005 and December 2016 were identified from a prospectively maintained institutional aortic surgery database. The primary outcome was AKI as defined by Risk, Injury, Failure, Loss, End Stage Renal Disease (ESRD) criteria. The association between minimum nasopharyngeal (NP) and bladder temperatures during HCA and postoperative AKI was assessed, adjusting for patient-level factors using multivariable logistic regression.

RESULTS

A total of 85% (n = 645) of patients underwent deep hypothermia (14.1-20.0°C), 11% (n = 83) low-moderate hypothermia (20.1-24.0°C) and 4% (n = 31) high-moderate hypothermia (24.1-28.0°C) as classified by NP temperature. When analysed by bladder temperature, 59% (n = 447) underwent deep hypothermia, 22% (n = 170) low-moderate, 16% (n = 118) high-moderate and 3% mild (n = 24) (28.1-34.0°C) hypothermia. The median systemic circulatory arrest time was 17 min. The incidence of AKI did not differ between hypothermia groups, whether analysed using minimum NP or bladder temperature. In the multivariable analysis, the association between degree of hypothermia and AKI remained non-significant whether analysed as a categorical variable (hypothermia group) or as a continuous variable (minimum NP or bladder temperature) (all P > 0.05).

CONCLUSIONS

In patients undergoing proximal aortic surgery including arch replacement requiring HCA, degree of systemic hypothermia was not associated with the risk of AKI. These data suggest that moderate hypothermia does not confer increased risk of AKI for patients requiring circulatory arrest, although additional prospective data are needed.

Long-term outcomes of hemiarch replacement with hypothermic circulatory arrest and retrograde cerebral perfusion

OBJECTIVE

This study sought to report outcomes of hemiarch replacement with hypothermic circulatory arrest and retrograde cerebral perfusion, and secondarily, to report outcomes of this operative approach by type of underlying aortic disease.

METHODS

This was an observational study of aortic surgeries from 2010 to 2018. All patients who underwent hemiarch replacement with retrograde cerebral perfusion were included, whereas patients undergoing partial or total arch replacement or concomitant elephant trunk procedures were excluded. Patients were dichotomized into 2 groups by underlying aortic disease; that is, acute aortic dissection (AAD) or aneurysmal degeneration of the aorta. These groups were analyzed for differences in short-term postoperative outcomes, including stroke and operative mortality (Society of Thoracic Surgeons definition). Multivariable Cox analysis was performed to identify variables associated with long-term survival after hemiarch replacement.

RESULTS

A total of 500 patients undergoing hemiarch replacement with hypothermic circulatory arrest plus retrograde cerebral perfusion were identified, of whom 53.0% had aneurysmal disease and 47.0% had AAD. For the entire cohort, operative mortality was 6.4%, whereas stroke occurred in 4.6% of patients. Comparing AAD with aneurysm, operative mortality and stroke rates were similar across each group. Five-year survival was 84.4% ± 0.02% for the entire hemiarch cohort, whereas 5-year survival was 88.0% ± 0.02% for the aneurysm subgroup and was 80.5% ± 0.03% for the AAD subgroup. On multivariable analysis, AAD was not associated with an increased hazard of death, compared with aneurysm (P = .790).

CONCLUSIONS

Morbidity and mortality after hemiarch replacement with hypothermic circulatory arrest plus retrograde cerebral perfusion are acceptably low, and this operative approach may be as advantageous for AAD as it is for aneurysm.

Risk Factors for Prolonged Mechanical Ventilation After Pulmonary Endarterectomy: 7 Years' Experience From an Experienced Hospital in China

Background: Prolonged mechanical ventilation (PMV) is common after cardiothoracic surgery, whereas the mechanical ventilation strategy after pulmonary endarterectomy (PEA) has not yet been reported. We aim to identify the incidence and risk factors for PMV and the relationship between PMV and short-term outcomes.

Methods: We studied a retrospective cohort of 171 who undergoing PEA surgery from 2014 to 2020. Cox regression with restricted cubic splines was performed to identify the cutoff value for PMV. The Least absolute shrinkage and selection operator regression and logistic regressions were applied to identify risk factors for PMV. The impacts of PMV on the short-term outcomes were evaluated.

Results: PMV was defined as the duration of mechanical ventilation exceeding 48 h. Independent risk factors for PMV included female sex (OR 2.911; 95% CI 1.303–6.501; P = 0.009), prolonged deep hypothermic circulatory arrest (DHCA) time (OR 1.027; 95% CI 1.002–1.053; P = 0.036), increased postoperative blood product use (OR 3.542; 95% CI 1.203–10.423; P = 0.022), elevated postoperative total bilirubin levels (OR 1.021; 95% CI 1.007–1.034; P = 0.002), increased preoperative pulmonary artery pressure (PAP) (OR 1.031; 95% CI 1.014–1.048; P < 0.001) and elongated postoperative right ventricular anteroposterior dimension (RVAD) (OR 1.119; 95% CI 1.026–1.221; P = 0.011). Patients with PMV had longer intensive care unit stays, higher incidences of postoperative complications, and higher in-hospital medical expenses.

Conclusions: Female sex, prolonged DHCA time, increased postoperative blood product use, elevated postoperative total bilirubin levels, increased preoperative PAP, and elongated postoperative RVAD were independent risk factors for PMV. Identification of risk factors associated with PMV in patients undergoing PEA may facilitate timely diagnosis and re-intervention for some of these modifiable factors to decrease ventilation time and improve patient outcomes.

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.

Brain Protection in Aortic Arch Surgery: An Evolving Field

Despite advances in cardiac surgery and anesthesia, the rates of brain injury remain high in aortic arch surgery requiring circulatory arrest. The mechanisms of brain injury, including permanent and temporary neurologic dysfunction, are multifactorial, but intraoperative brain ischemia is likely a major contributor. Maintaining optimal cerebral perfusion during cardiopulmonary bypass and circulatory arrest is the key component of intraoperative management for aortic arch surgery. Various brain monitoring modalities provide different information to improve cerebral protection. Electroencephalography gives crucial data to ensure minimal cerebral metabolism during deep hypothermic circulatory arrest, transcranial Doppler directly measures cerebral arterial blood flow, and near-infrared spectroscopy monitors regional cerebral oxygen saturation. Various brain protection techniques, including hypothermia, cerebral perfusion, pharmacologic protection, and blood gas management, have been used during interruption of systemic circulation, but the optimal strategy remains elusive. Although deep hypothermic circulatory arrest and retrograde cerebral perfusion have their merits, there have been increasing reports about the use of antegrade cerebral perfusion, obviating the need for deep hypothermia. With controversy and variability of surgical practices, moderate hypothermia, when combined with unilateral antegrade cerebral perfusion, is considered safe for brain protection in aortic arch surgery performed with circulatory arrest. The neurologic outcomes of brain protection in aortic arch surgery largely depend on the following three major components: cerebral temperature, circulatory arrest time, and cerebral perfusion during circulatory arrest. The optimal brain protection strategy should be individualized based on comprehensive monitoring and stems from well-executed techniques that balance the major components contributing to brain injury.

Influence of moderate hypothermic circulatory arrest on outcome in patients undergoing elective replacement of thoracic aorta

Background

The ideal technique of cerebral protection in the surgical operation of the ascending aorta.is currently controversial. The current analysis evaluates the influence of moderate hypothermic circulatory arrest (MHCA) on elective replacement of the ascending aorta.

Methods

The study included 905 consecutive patients between 2001 and 2015, who underwent replacement of ascending aorta in MHCA. Patients were divided according to the postoperative 30-day mortality into survivor und non-survivor group.

Results

The average age was 66.5±11.1 in survivors vs. 70.0±10.5 years in non-survivors (P=0.057). The survivor group had a significantly lower Euro-SCORE II than non-survivors [4.0% (2.3, 6.6) vs. 9.5% (4.8, 20.9); P<0.001)]. The incidence of coronary heart disease (38.0% vs. 58.3%; P=0.022) and chronic renal failure (10.0% vs. 33.3%, P<0.001 was significantly higher in non-survivors. Intraoperatively, the cardiopulmonary bypass time [140 min (112, 185) vs. 194 min (164, 271); P<0.001] and cross-clamping time [91 min (64, 124) vs.119 min (94, 157); P<0.001] were significantly longer in non-survivors. However, the MHCA time was similar in both groups with statistical significance (P=0.023). Postoperatively, re-exploration due to bleeding was highly significant in non-survivors (5.4% vs. 33.3%; P<0.001) with a higher incidence of stroke (4.6% vs. 33.3%; P<0.001). The duration of mechanical ventilation was significantly shorter in survivors than in non-survivors [17 h (12, 26) vs. 147 h (49, 337); P<0.001] with a lower incidence of pulmonary infection (6.0% vs.16.7%; P=0.023). The multivariable logistic regression analysis showed age, female gender, aortic aneurysm, additional CABG, total arch replacement and cardiopulmonary bypass time were independent risk factors for 30-day mortality.

Conclusions

The acceptable morbidity and mortality rates show that MHCA can be considered as a safe technique for cerebral protection in surgical replacement of thoracic aorta.

Total debranching thoracic endovascular aortic repair with elephant trunk insertion technique

We report successful total debranching thoracic endovascular aortic repair using the elephant trunk insertion technique without hypothermic circulatory arrest for a 56-year-old man who developed aortic arch dissection and ascending aortic aneurysm. In the first step, an elephant trunk graft was inserted into the ascending aorta under cardiopulmonary bypass, and a branched prosthetic graft was attached to the ascending aorta. The left common carotid artery and brachiocephalic artery were sequentially anastomosed to the branched graft. The second step was thoracic endovascular aortic repair covering the elephant trunk to the distal arch. Postprocedure digital subtraction angiography showed no endoleaks or false lumen.

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.

Managing acute type A aortic dissections: Is a universal approach feasible?

The goal in the treatment of acute type A aortic dissection (ATAAD) is to resect the primary intimal tear while minimizing associated complications of the disease. This goal can be accomplished by different surgical techniques and operative strategies. The extent of proximal and distal aortic reconstruction and the use of cerebral perfusion adjuncts are highly variable between institutions and within institutions themselves. As operative outcomes for ATAAD have improved considerably over the past decade, the focus has shifted towards extensive aortic reconstruction to minimize aortic reinterventions. However, there remains a distinct difference in how patients with ATAAD are managed in North America when compared with those in East Asia.

A simple method to establish antegrade cerebral perfusion during hemiarch reconstruction

Objective

We describe a novel and safe technique using a 12F-14F pediatric arterial cannula to establish unilateral, selective, antegrade cerebral perfusion (ACP) during open hemiarch reconstruction.

Methods

Between January 2015 and September 2018, 42 patients underwent elective aortic aneurysm repair requiring an open distal anastomosis and at least a hemiarch replacement via hypothermic circulatory arrest by 2 surgeons. All distal reconstructions were performed at moderate hypothermia (22°C-26°C) with direct cannulation of the innominate artery (IA) using a pediatric arterial cannula to allow ACP at 10-15 mL/kg/min. Data were collected by retrospective chart review.

Results

Thirty-one of the 42 patients (74%) were male. The mean patient age was 65 ± 13 years, and the mean body surface area was 2.1 ± 0.3 m². Proximal repairs included a modified Bentall with a valve-graft composite (n = 17), valve-sparing root replacement (n = 2), and aortic valve replacement (n = 15). Perioperative mortality was 2% (n = 1), and the incidence of stroke was 0%. The mean lowest core body temperature reached during circulatory arrest was 23.8 ± 2.7°C with a mean ACP time of 21.8 ± 3.6 minutes. The mean aortic cross-clamp and cardiopulmonary bypass times were 160.6 ± 55.5 minutes and 204.7 ± 57.5 minutes, respectively. There were no cases of IA injury.

Conclusions

Direct IA cannulation with a pediatric arterial cannula is a safe and efficient method to allow ACP in aortic surgery requiring hypothermic circulatory arrest and may circumvent the potential complications of axillary cannulation.

Utility of neuromonitoring in hypothermic circulatory arrest cases for early detection of stroke: Listening through the noise

OBJECTIVE

Stroke remains a potentially devastating complication of aortic arch intervention. The value of neurophysiologic intraoperative monitoring (NIOM) in the early identification of stroke is unclear. We evaluated the utility of NIOM for early stroke detection in aortic arch surgery.

METHODS

Across 8 years at our institution, 365 patients underwent aortic arch surgery with hypothermic circulatory arrest, and 224 cases utilized NIOM. One patient was excluded for intraoperative death. In the remaining cohort, we reviewed the incidence, timing, and location of strokes, and the incidence and nature of NIOM alerts.

RESULTS

Hemiarch was performed in 154 patients and total arch replacement in 69 patients. Stroke occurred in 6.3% of all cases (14 out of 223), 15.9% of total arches (11 out of 69), and 2.0% of hemiarches (3 out of 154). There were 33 NIOM alerts (14.8%), and 9 patients had both alerts and stroke. Of these, NIOM deficits plausibly correlated with imaging findings in 7 cases (78%). Of the 5 stroke patients without NIOM alerts, 2 developed neurologic symptoms 3 days or more postoperatively, and infarcts in 3 patients did not result in sensory or motor deficits. Excluding 2 patients with late stroke, the sensitivity of NIOM for stroke detection was 75%, specificity was 88.5%, positive predictive value was 27.3%, and negative predictive value was 97.4%.

CONCLUSIONS

Despite a low positive predictive value requiring a high level of discrimination when interpreting abnormal findings, NIOM has high sensitivity and specificity for the early stroke detection. Furthermore, its high negative predictive valve is reassuring for low risk of stroke in the absence of alerts.

COMMENCE trial (Comparing hypOtherMic teMperaturEs duriNg hemiarCh surgEry): a randomized controlled trial of mild vs moderate hypothermia on patient outcomes in aortic hemiarch surgery with anterograde cerebral perfusion

Background

Aortic arch surgery remains the only viable life-saving treatment for aortic arch disease. However, the necessity for cessation of systemic blood flow with hypothermic cardiac arrest carries substantial risk of morbidity and mortality, including poor neurological outcomes and kidney failure. While uncontrolled studies have suggested the safety of operating at warmer temperatures, significant variables remain un-investigated, supporting the need for a randomized clinical trial (RCT) to produce evidence-based guidelines for perfusion strategies in aortic surgery. This study proposes a multi-center RCT in order to compare outcomes of warmer hypothermic strategies during aortic hemiarch surgery on a composite endpoint of neurologic and acute kidney injury (AKI).

Methods/design

This is a prospective multi-center, single-blind two-arm RCT comparing mild (32 °C) versus moderate (26 °C) hypothermic cardiac arrest in patients (n = 282) undergoing hemiarch surgery with antegrade cerebral perfusion (ACP). The primary endpoint is a composite of neurological injury (incidence of transient ischemic attack and/or stroke) and Kidney Disease Improving Global Outcomes (KDIGO) stage 1 or higher AKI. Secondary outcomes include death, cardiopulmonary bypass time, bleeding, transfusion rates, prolonged mechanical ventilation, myocardial infarction, length of stay, and quality of life measures.

Patients will undergo 1:1 block randomization to each treatment arm on day of surgery. Sequence of operation will be at the surgeon’s discretion with mandatory guidelines for temperature and ACP administration. Perioperative management will occur as per enrolling center standard of care. Neurocognitive function will be assessed for neurological injury using validated neurological screening tests: NIHSS, MOCA, BI, and MRS throughout patient follow-up. Diagnosis and classification of AKI will be based on rising creatinine values as per the KDIGO criteria. Study duration for each patient will be 60 ± 14 days.

Discussion

It is hoped that performing hemiarch surgery using mild hypothermia (32 °C) and selective ACP will result in a 15% absolute risk reduction in the composite outcomes. The potential of this risk reduction will translate into improved patient outcomes, survival, and long-term financial savings to the health care system. In addition, the results of this trial will be used to create the first-ever guidelines for temperature management strategy during aortic surgery.

Trial registration

This trial is registered on ClinicalTrials.gov with the registration number NCT02860364. Registration date August 9th, 2016.

Sex-Specific Outcome after Ascending Aortic Surgery in Moderate Hypothermic Circulatory Arrest

BACKGROUND

Historically, female patients had worse outcome undergoing heart surgery. No recent data exist on gender-specific outcome after moderate hypothermic circulatory arrest (MHCA). The aim of this large retrospective analysis was to investigate gender disparity in patients undergoing elective surgery of ascending aorta in MHCA at 24°C.

METHODS

We conducted a retrospective review of 905 (33.3% female) cases of elective heart surgery in MHCA for ascending aortic aneurysm (90.9%) or severely calcified aorta (12.5%) between 2001 and 2015. Furthermore, 299 female and 299 male patients matched by propensity score were compared. Patients with dissection of the aorta were excluded.

RESULTS

Women were older (68.4 ± 9.9 vs. 65.8 ± 11.6 years; p = 0.002), had higher logistic EuroSCORE I (18.4 [11.7; 29.2] vs. 12.3% [7.4; 22.6]; p < 0.001), and significantly shorter cardiopulmonary bypass (CPB) time (132 [105; 175] vs. 150 [118; 192] minutes; p < 0.001), while mean MHCA time was longer (15 [13; 19] vs. 14 [12; 17] minutes; p = 0.003). Surgical procedures were less complex in women and they were treated more frequently by isolated supracoronary ascending aorta replacement (61 vs. 54%; p = 0.046). Postoperatively, men showed a higher incidence of neurologic complications (7.0 vs. 3.3%; p = 0.03). The 30-day mortality (women 4.9% vs. men 3.9%; p = 0.48) did not differ significantly, likewise after statistical matching (4.7 vs. 2.3%; p = 0.120). Age, CPB time, and blood transfusion, but not female gender, were risk factors for mortality in multivariable regression analysis.

CONCLUSION

This study supports the hypothesis that female gender is not associated with increased short-term mortality or perioperative adverse events in elective aortic surgery in MHCA.

Selective brain hypothermia: feasibility and safety study of a novel method in five patients

BACKGROUND/OBJECTIVE

Reduction of brain temperature remains the most common method of neuroprotection against ischemic injury employed during cardiac surgery. However, cooling delivered via the cardiopulmonary bypass circuit is brief and cooling the body core along with the brain has been associated with a variety of unwanted effects. This study investigated the feasibility and safety of a novel selective brain cooling approach to induce rapid, brain-targeted hypothermia independent of the cardiopulmonary bypass circuit.

METHODS

This first-in-human feasibility study enrolled five adults undergoing aortic valve replacement with cardiopulmonary bypass support. During surgery, the NeuroSave system circulated chilled saline within the pharynx and upper esophagus. Brain and body core temperature were continuously monitored. Adverse effects, cardiopulmonary function, and device function were noted.

RESULTS

Patient 1 received cooling fluid for an insignificant period, and Patients 2-5 successfully underwent the cooling procedure using the NeuroSave system for 56-89 minutes. Cooling fluid was 12°C for Patients 1-3, 6°C for Patient 4, and 2°C for Patient 5. There were no NeuroSave-related adverse events and no alterations in cardiopulmonary function during NeuroSave use. Brain temperature decreased by 3°C within 15 minutes and remained at least 3.5°C colder than the body core. During a brief episode of hypotension in one patient, the brain cooled an additional 4°C in 2 minutes, briefly reaching 27.4°C.

CONCLUSION

The NeuroSave system can induce rapid brain-targeted hypothermia and simultaneously maintain a favorable body-brain temperature gradient, even during hypotension. Further studies are required to evaluate the function of the system during longer periods of use.

Perioperative Outcomes of Using Different Temperature Management Strategies on Pediatric Patients Undergoing Aortic Arch Surgery: A Single-Center, 8-Year Study

Background: With the widespread application of regional low-flow perfusion (RLFP), development of surgical techniques, and shortened circulatory arrest time, deep hypothermia is indispensable for organ protection. Clinicians have begun to increase the temperature to reduce hypothermia-related adverse outcomes. The aim of this study was to evaluate the safety and efficacy of elevated temperatures during aortic arch surgery with lower body circulatory arrest (LBCA) combined with RLFP. Methods: We retrospectively analyzed data from 207 consecutive pediatric patients who underwent aortic arch repair with LBCA & RLFP between January 2010 and July 2017 and evaluated different hypothermia management strategies. The overall cohort was divided into three groups: deep hypothermia (DH, 20.0-25.0°C), moderate hypothermia (MoH, 25.1-30.0°C) and mild hypothermia (MH, 30.1-34.0°C). Results: The percentage of AKI-1 occurrences was significantly increased in the MH group (51.52%) compared to those in the DH (25.40%) and MoH (37.84%) groups (P = 0.036); prolonged hospital stay occurrences were decreased with elevated temperature (DH 47.62%, MoH 28.83%, MH 18.18%, P = 0.006). Neurological complications, peritoneal dialysis, hepatic dysfunction, 30-day hospital mortality, delay extubation occurrences were no significant among the groups. Logistic analysis showed that the MH group was negatively associated with post-op AKI-1 compared with the DH group [OR = 0.329 (0.137-0.788), P = 0.013], no differences were found between the MoH and the MH group. Compared to other groups, the intubation time (P = 0.006) and postoperative hospital stay (P = 0.009) were significantly decreased in the MH group. Multivariate logistic analysis showed hypothermia levels were not significant with prolonged hospital stay. Conclusions: This retrospective analysis demonstrated that for pediatric patients undergoing surgeries with RLFP & LBCA, three different gradient temperature management strategies are available: deep, moderate, and mild hypothermia. Utilizing mild or moderate hypothermia is safe and feasible. Although the number of AKI-1 occurrences in the MH group was significantly increased compared to those in the other groups, further analysis showed no significance in the MoH and MH group, mild hypothermia management is as safe as others when used appropriately.

Intraoperative care for aortic surgery using circulatory arrest

The total circulatory arrest (CA) is necessary to achieve optimal surgical conditions in certain aortic pathologies, especially in those affecting the ascending aorta and aortic arch. During this procedure it is necessary to protect all the organs of ischemia, especially those of the central nervous system and for this purpose several strategies have been developed. The first and most important protective method is systemic hypothermia. The degree of hypothermia and the route of application have been evolving and currently tend to use moderate hypothermia (MH) (20.1-28 °C) associated with unilateral or bilateral selective cerebral perfusion methods. In this way the neurological results are better, the interval of security is greater and the times of extracorporeal circulation are smaller. Even so, it is necessary to take into account that there is the possibility of ischemia in the lower part of the body, especially of the abdominal viscera and the spinal cord, therefore the time of circulatory stop should be limited and not to exceed 80 minutes. Evidence of possible neurological drug protection is very weak and only mannitol, magnesium, and statins can produce some benefit. Inhalational anesthetics and some intravenous seem to have advantages, but more studies would be needed to test their long-term benefit. Other important parameters to be monitored during these procedures are blood glucose, anemia and coagulation disorders and acid-base balance. The recommended monitoring is common in complex cardiovascular procedures and it is of special importance the neurological monitoring that can be performed with several techniques, although currently the most used are Bispectral Index (BIS) and Near-Infrared Spectroscopy (NIRS). It is also essential to monitor the temperature routinely at the nasopharyngeal and bladder level and it is important to control coagulation with rotational thromboelastometry (ROTEM).

Hemiarch: The Real Operation for Ascending Aortic Aneurysm

The extent and technique of resection for ascending aortopathies remains debated. The 2 main camps are divided into those who believe in the hemiarch resection utilizing hypothermic circulatory arrest and those who feel that the same goal can be accomplished with just an ascending aortic resection with an aortic cross clamp. While this debate continues to happen within groups and in some cases even in the same hospital, it certainly has not happened in the literature. There are no studies directly comparing the safety and efficacy of these 2 ideologies. The aim of this review is to present the little data that do exist and to ultimately show that the hemiarch technique is superior after careful deliberation.

Neurophysiological Intraoperative Monitoring During Aortic Arch Surgery

Circulatory management during replacement of the aortic arch is complex and involves a period of circulatory arrest to provide a bloodless field during arch vessel anastomosis. To guard against ischemic brain injury, tissue metabolic demand is reduced by systemically cooling the patient prior to circulatory arrest. Neurophysiological intraoperative monitoring (NIOM) is often used during the course of these procedures to provide contemporaneous assessment of brain status to help direct circulatory management decisions and detect brain ischemia. In this review, we discuss the characteristics of electrocerebral activity through the process of cooling, circulatory arrest, and rewarming as depicted through commonly used NIOM modalities, including electroencephalography and peripheral nerve somatosensory-evoked potentials. Attention is directed toward the role NIOM has traditionally played during deep hypothermic circulatory arrest, where it is used to define the point of electrocerebral inactivity or maximal cerebral metabolic suppression prior to initiating circulatory arrest while also discussing the evolving utility of NIOM when systemic circulatory arrest is initiated at more moderate degrees of hypothermia in conjunction with regional brain perfusion. The use of cerebral tissue oximetry by near-infrared spectroscopy as an alternative NIOM modality during surgery of the aortic arch is addressed as well. Finally, special considerations for NIOM and the detection of spinal cord ischemia during hybrid aortic arch repair and emerging operative techniques are also discussed.

Does moderate hypothermia really carry less bleeding risk than deep hypothermia for circulatory arrest? A propensity-matched comparison in hemiarch replacement

BACKGROUND

Moderate (MHCA) versus deep (DHCA) hypothermia for circulatory arrest in aortic arch surgery has been purported to reduce coagulopathy and bleeding complications, although there are limited data supporting this claim. This study aimed to compare bleeding-related events after aortic hemiarch replacement with MHCA versus DHCA.

METHODS

Patients who underwent hemiarch replacement at a single institution from July 2005 to August 2014 were stratified into DHCA and MHCA groups (minimum systemic temperature ≤20°C and >20°C, respectively) and compared. Then, 1:1 propensity matching was performed to adjust for baseline differences.

RESULTS

During the study period, 571 patients underwent hemiarch replacement: 401 (70.2%) with DHCA and 170 (29.8%) with MHCA. After propensity matching, 155 patients remained in each group. There were no significant differences between matched groups with regard to the proportion transfused with red blood cells, plasma, platelet concentrates, or cryoprecipitate on the operative day, the rate of reoperation for bleeding, or postoperative hematologic laboratory values. Among patients who received plasma, the median transfusion volume was statistically greater in the DHCA group (6 vs 5 units, P = .01). MHCA also resulted in a slight reduction in median volume of blood returned via cell saver (500 vs 472 mL, P < .01) and 12-hour postoperative chest tube output (440 vs 350, P < .01). Thirty-day mortality and morbidity did not differ significantly between groups.

CONCLUSIONS

MHCA compared with DHCA during hermiarch replacement may slightly reduce perioperative blood-loss and plasma transfusion requirement, although these differences do not translate into reduced reoperation for bleeding or postoperative mortality and morbidity.