Hypothermic Circulatory Arrest in Adult Aortic Arch Surgery: A Review of Hypothermic Circulatory Arrest and its Anesthetic Implications

Diseases affecting the aortic arch often require surgical intervention. Hypothermic circulatory arrest (HCA) enables a safe approach during open aortic arch surgeries. Additionally, HCA provides neuroprotection by reducing cerebral metabolism and oxygen requirements. However, HCA comes with significant risks (eg, neurologic dysfunction, stroke, and coagulopathy), and the cardiac anesthesiologist must completely understand the surgical techniques, possible complications, and management strategies.

Neuroprotection during Open Aortic Arch Surgery: Cerebral Perfusion Methods and Temperature

Neuroprotection is important in open aortic arch surgery because of the dependence of brain tissues on cerebral perfusion. Therefore, several techniques have been developed to reduce cerebral ischemia and improve outcomes in open aortic arch surgery. In this review, I describe various neuroprotective strategies, such as profound and deep hypothermic circulatory arrest, selective antegrade cerebral perfusion, retrograde cerebral perfusion, and lower body circulatory arrest; compare their advantages and disadvantages, and discuss their evolution and current status by reviewing relevant literature.

Outcomes of surgery for acute type A dissection in octogenarians versus non-octogenarians: a systematic review and meta analysis

INTRODUCTION

Acute Type A Aortic Dissection (ATAAD) is a cardiothoracic emergency that requires urgent intervention. Elderly status, particularly age over 80, is an independent risk factor for mortality and morbidity. The mid-term outcomes of this age group are also unknown. This systematic review and meta-analysis of observational studies was therefore performed to analyse short- and mid-term mortality and morbidity in octogenarians following surgery for ATAAD.

METHODS

A systematic review was conducted for studies published since January 2000. The primary endpoint was short-term mortality, either reported as 30-day mortality or in-hospital mortality and medium-term (five year) survival. Secondary endpoints were rates of postoperative complications, namely stroke, acute renal failure (ARF), re-exploration and intensive care unit (ICU) length of stay (LOS).

RESULTS

A total of 16 retrospective studies, with a total of 16, 641 patients were included in the systematic review and meta-analysis. Pooled analysis demonstrated that octogenarian cohorts are at significantly higher risk of short-term mortality than non-octogenarians (OR 1.93; 95% CI 1.33-2.81; P < 0.001). Actuarial survival was significantly lower in the octogenarian cohort, with a five-year survival in the octogenarian cohort of 54% compared to 76% in the non-octogenarian cohort (P < 0.001). There were no significant differences between the cohorts in terms of secondary outcomes: stroke, ARF, re-exploration or ICU LOS.

CONCLUSION

Octogenarians are twice as likely to die in the short-term following surgery for ATAAD and demonstrate a significantly lower five-year actuarial survival. Patients and family members should be well informed of the risks of surgery and suitable octogenarians selected for surgery.

Evaluation of health outcomes after the implementation of rotational thromboelastometry in patients undergoing cardiac surgery

BACKGROUND

Viscoelastic tests (rotational thromboelastometry, ROTEM^®), together with the implementation of a specific algorithm for coagulation management in cardiac surgery, enable perioperative coagulopathy to be better controlled.

METHODS

Retrospective cohort study including 675 patients who underwent cardiac surgery with cardiopulmonary bypass. The incidence of allogeneic blood transfusions and clinical postoperative complications were analyzed before and after ROTEM^® implementation.

RESULTS

Following viscoelastic testing and the implementation of a specific algorithm for coagulation management, the incidence of any allogeneic blood transfusion decreased (41.4% vs 31.9%, p = .026) during the perioperative period. In the group monitored with ROTEM^®, decreased incidence of transfusion was observed for packed red blood cells (31.3% vs 19.8%, p = .002), fresh frozen plasma (9.8% vs 3.8%, p = .008), prothrombin complex concentrate administration (0.9% vs 0.3%, p = .599) and activated recombinant factor VII (0.3% vs 0.0%, p = .603). Increased incidence was observed for platelet transfusion (4.8% vs 6.8%, p = .530) and fibrinogen concentrate (0.9% vs 3.5%, p = .066), tranexamic acid (0.0% vs 0.6%, p = .370) and protamine administration (0.6% vs 0.9%, p = .908). Similar results were observed in the postoperative period, but with a decreased incidence of platelet transfusion (4.8% vs 3.8%, p = .813). In addition, statistically significant reductions were detected in the incidence of postoperative bleeding (9.5% vs 5.3%, p = .037), surgical reexploration (6.0% vs 2.9%, p = .035), and length of Intensive Care Unit (ICU) stay (6.0 days vs 5.3 days, p = .026).

CONCLUSIONS

The monitoring of hemostasis by ROTEM^® in cardiac surgery, was associated with decreased incidence of allogeneic blood transfusion, clinical hematologic postoperative complications and lengths of ICU stay.

Is total aortic arch replacement with the frozen elephant trunk procedure reasonable in elderly patients?

OBJECTIVES

Total aortic arch replacement is an invasive procedure with significant risks for complications. These risks are even higher in older, multimorbid patients. The current trends in demographic changes in western countries with an ageing population will aggravate this issue. In this study, we present our experience with total aortic arch replacement using the frozen elephant trunk (FET) technique in septuagenarians. We compared the results of septuagenarians with those of younger patients and analysed if there was an improvement in outcome over time.

METHODS

Between August 2001 and March 2020, 225 patients underwent non-urgent FET procedure at our institution. There were 75 patients aged ≥70 years (mean age 74 ± 4) who were assigned to group A, and 150 patients aged <70 years (mean age of 57 ± 11) who were assigned to group B. In groups A and B, the indications for surgery were chronic dissection (21% vs 53%), aortic aneurysm (78% vs 45%) and penetrating atherosclerotic ulcer (1% vs 2%).

RESULTS

The rate for temporary dialysis was significantly higher in group A than in group B (29% vs 13%, P = 0.003), although the majority recovered kidney function. Rates for re-exploration for bleeding and stroke were comparable in both groups. In-hospital mortality was significantly higher in group A than in group B (24% vs 13%, P = 0.037). Logistic regression analysis showed that age >70 years was an independent statistically significant risk factor for in-hospital mortality (odds ratio = 2.513, 95% confidence interval = 1.197-5.278, P-value = 0.015). Follow-up was complete for 100% of patients and comprised a total of 1073 patient-years with a mean follow-up time of 4.8 ± 4.5 years. The 1- and 5-year survival rates were 68% and 49% in group A, and 85% and 71% in group B, respectively (log rank, P < 0.001). Survival did not significantly improve over time.

DISCUSSION

Total aortic arch replacement using the FET technique has a significantly higher risk for perioperative morbidity and mortality in septuagenarians than in younger patients. Long-term survival is significantly impaired in older patients. We recommend thorough patient selection of those who require total aortic arch replacement, and optimization of perioperative management to improve outcomes.

Is debranching thoracic endovascular aortic repair acceptable as the first choice for arch aneurysm in the elderly?

OBJECTIVES

This study aimed to assess differences in midterm outcomes between total arch replacement (TAR) and debranching thoracic endovascular aortic repair (d-TEVAR) and to evaluate the validity of d-TEVAR as the preferred treatment choice for aortic arch aneurysm in the elderly.

METHODS

We reviewed the case histories of 86 patients who had undergone TAR (64 men; mean age 78 ± 2.9 years) and 121 patients who had undergone d-TEVAR (90 men; mean age 82 ± 4.5 years) between 2007 and 2017; of these patients, 50 from each group were matched based on propensity scores to adjust for differences in patient characteristics.

RESULTS

Rates of freedom from all-cause mortality at 2 and 4 years were similar between the 2 groups (88% and 77% in the TAR group vs 82% and 64% in the d-TEVAR group, P = 0.11), but rates of freedom from reintervention at 2 and 4 years were significantly higher in the TAR group (100% and 96%) than in the d-TEVAR group (97% and 88%) (P = 0.004). Propensity score matching yielded similar survival rates of 88% and 85% for TAR vs 86% and 71% for d-TEVAR (P = 0.53) and comparable freedom from reintervention rates (100% and 97% in TAR, 98% and 90% in d-TEVAR, P = 0.16) at 2 and 4 years. Cox regression analysis identified previous cerebral infarction [hazard ratio (HR) 3.9; P = 0.005 in TAR/HR 3.1; P = 0.002 in d-TEVAR] as an independent positive predictor of overall mortality in both groups.

CONCLUSIONS

Midterm outcomes after TAR and d-TEVAR were satisfactory and propensity score matching-based evaluation revealed no significant differences in outcomes, implying that d-TEVAR is an acceptable first-choice procedure for aortic arch aneurysm in patients older than 75 years.

Neuroprotective Strategies in Repair and Replacement of the Aortic Arch

Aortic arch surgery is a technical challenge, and cerebral protection during distal anastomosis is a continued topic of controversy and discussion. The physiologic effects of hypothermic arrest and adjunctive cerebral perfusion have yet to be fully defined, and the optimal strategies are still undetermined. This review highlights the historical context, physiological rationale, and clinical efficacy of various neuroprotective strategies during arch operations.

Brain protection in aortic arch aneurysm: antegrade or retrograde?

During open aortic arch repair, there is an interruption of cerebral perfusion and to prevent neurological sequelae, the hypothermic circulatory arrest has been established to provide sufficient brain protection coupled with adjuncts including retrograde and antegrade cerebral perfusion. To date, brain protection during open aortic arch repair is a contested topic as to which provides superior brain protection with little evidence existing to suggest supremacy of one modality over the other. This article reviews current literature reflecting on key and emerging studies in brain protection and their associated outcomes in patients undergoing open aortic arch surgery.

Clinical significance of chronic obstructive pulmonary disease in patients undergoing elective total arch replacement: analysis based on the Japan Adult Cardiovascular Surgery Database

Objectives

We investigated the impact of chronic obstructive pulmonary disease (COPD) on in-hospital outcomes of patients undergoing conventional total aortic arch replacement (TAR), based on the Japan Adult Cardiovascular Surgery Database.

Methods

A total of 12 590 patients who underwent elective TAR between 2008 and 2013 were retrospectively reviewed. Patients were divided into 4 categories: normal respiratory function (control), with ratio of forced expiratory volume of air in 1 s (FEV 1 ) to forced vital capacity (FVC) of 76% or greater (TAR, n  = 10 040); mild COPD, with FEV 1 /FVC ratio 60-75% and/or use of bronchodilator (TAR, n  = 1890); moderate COPD, FEV 1 /FVC ratio 50 to 59% and/or use of steroids (TAR, n  = 504); and severe COPD, FEV 1 /FVC ratio less than 50% and/or presence of respiratory failure (TAR, n  = 156).

Results

In-hospital mortality was 5.7% (5.2% in controls, 7.0% in mild COPD, 9.3% in moderate COPD and 9.0% in severe COPD). A significant trend towards the severity of COPD was noted ( P  < 0.0001). A higher incidence of postoperative pneumonia (6.0% in control, 11.0% in mild COPD, 12.3% in moderate COPD and 15.4% in severe COPD; P  < 0.0001) and a greater need for prolonged ventilation (17.5% in control, 22.0% in mild COPD, 26.6% in moderate COPD and 29.5% in severe COPD; P  < 0.0001) were observed in cases of more severe COPD. The odds ratio of moderate/severe COPD for in-hospital mortality was 1.44 with confidence interval of 1.08-1.91 ( P  = 0.012).

Conclusions

There was a significant increase in in-hospital mortality and morbidity with increasing severity of COPD in patients who underwent TAR.

Long-term outcome and quality of life following emergency surgery for acute aortic dissection type A: a comparison between young and elderly adults

Objectives

Innovations in surgical techniques and perioperative management have continuously improved survival rates for acute aortic dissection type A (AADA). The aim of our study was to evaluate long-term outcome and quality of life (QoL) after surgery for AADA in elderly patients compared with younger patients.

Methods

We retrospectively evaluated 242 consecutive patients, who underwent surgery for AADA between January 2004 and April 2014. Patients were divided into two groups: those aged 70 years and older (elderly group; n  = 78, mean age, 76 ± 4 years) and those younger than 70 years (younger group; n  = 164, mean age, 56 ± 10 years). QoL was assessed with the Short Form Health Survey Questionnaire (SF-36) 1 year after surgery.

Results

The questionnaire return rate was 91.0%. There were already significant differences noted between the two groups with regard to preoperative risk factors on admission. The clinical presentation with a cardiac tamponade was higher in the elderly group (62.8% vs 47.6%; P  = 0.03). Intraoperatively, complex procedures were more common in the younger group (21.3% vs 5.2%; P  = 0.001). Accordingly, cardiopulmonary bypass and cross-clamping times were significantly longer in the younger group. The operative mortality was similar in both groups (3.8% vs 1.2%; P  = 0.33). In the elderly population, 30-day mortality was higher (21.8% vs 7.9%; P  = 0.003). One-year (72% vs 85%), 3-year (68% vs 84%) and 5-year (63% vs 79%) survival rates were satisfactory for the elderly group, but significantly lower compared with the younger group ( P  = 0.008). The physical component summary score also was similar between the groups (39.14 ± 11.12 vs 39.12 ± 12.02; P  = 0.99). However, the mental component summary score might be slightly higher in the elderly group but not statistically significant (51.61 ± 10.73 vs 48.63 ± 11.25; P  = 0.12).

Conclusions

Satisfactory long-term outcome and the general perception of well-being encourage surgery in selected elderly patients with AADA.

Antegrade cerebral perfusion at 25 °C for arch reconstruction in newborns and children preserves perioperative cerebral oxygenation and serum creatinine

BACKGROUND

Antegrade cerebral perfusion (ACP) typically is used with deep hypothermia for cerebral protection during aortic arch reconstructions. The impact of ACP on cerebral oxygenation and serum creatinine at a more tepid 25 °C was studied in newborns and children.

METHODS

Between 2010 and 2014, 61 newborns and children (<5 years old) underwent aortic arch reconstruction using moderate hypothermia (25.0±0.9 °C) with ACP and a pH-stat blood gas management strategy. These included 44% Norwood-type operations, 30% isolated arch reconstructions, and 26% arch reconstructions with other major procedures. Median patient age at surgery was 9 days (range, 3 days-4.7 years). Cerebral oxygenation (NIRS) was monitored continuously perioperatively for 120 hours. Serum creatinine was monitored daily.

RESULTS

Median cardiopulmonary bypass (CPB) and cross clamp times were 181 minutes (range, 82-652 minutes) and 72 minutes (range, 10-364 minutes), respectively. ACP was performed at a mean flow rate of 46±6 mL/min/kg for a median of 48 minutes (range, 10-123 minutes). Cerebral and somatic NIRS were preserved intraoperatively and remained at baseline postoperatively during the first 120 hours. Peak postoperative serum creatinine levels averaged 0.7±0.3 mg/dL for all patients. There were 4 (6.6%) discharge mortalities. Six patients (9.8%) required ECMO support. Median postoperative length of hospital and intensive care unit (ICU) stay were 16 days(range, 4-104 days) and 9 days (range, 1-104 days), respectively. Two patients (3.3%) received short-term peritoneal dialysis for fluid removal, and none required hemodialysis. Three patients (4.9%) had an isolated seizure which resolved with medical therapy, and none had a neurologic deficit or stroke.

CONCLUSIONS

ACP at 25 °C preserved perioperative cerebral oxygenation and serum creatinine for newborns and children undergoing arch reconstruction. Early outcomes are encouraging, and additional study is warranted to assess the impact on late outcomes.

Double arterial perfusion strategy for extensive thoracic aortic surgery to avoid lower body hypothermic circulatory arrest

OBJECTIVE

To analyse our results of using a double arterial perfusion strategy to avoid lower body hypothermic circulatory arrest after extensive thoracic aortic surgery.

METHODS

We analysed the intra- and perioperative courses of 10 patients (median age 58 years, median logistic EuroSCORE 14.6) who underwent extensive thoracic aortic surgery with a double arterial perfusion strategy. The main goal of double arterial perfusion is to separate myocardial and supra-aortic from systemic perfusion. Aortic repair starts at the most distal level of the descending aorta, followed by reinsertion of the supra-aortic vessels, and ends with completion of the proximal anastomosis or by any kind of root repair as needed.

RESULTS

Seven of 10 patients had prior surgery of the thoracic aorta. Indications for surgery were post-dissection aneurysm in 4 patients, true aneurysm in 3, anastomotic aneurysms in 2 and Type B aortic dissection with pseudo-coarctation in 1. Surgical access was performed through median sternotomy with left hemi-clamshell extension in all cases. There was no in-hospital mortality, but perioperative neurological symptoms occurred in 2 patients. These 2 patients developed delayed stroke (after awaking) after an initial uneventful clinical course, and in 1 of them, neurological symptoms resolved completely during follow-up. The median follow-up was 7 (± 13) months. There was no death and no need for additional redo surgery during this observational period.

CONCLUSIONS

Extensive surgery of the thoracic aorta using a double arterial perfusion technique in order to avoid lower body hypothermic circulatory arrest is an attractive option. Further refinements of this technique may enable the safe and effective simultaneous multisegmental treatment of thoracic aortic pathology in patients who would otherwise have to undergo a two-step surgical approach.

Usefulness of Deep Hypothermic Circulatory Arrest and Regional Cerebral Perfusion in Children

To compare the safety and usefulness of deep hypothermic circulatory arrest (DHCA) and regional cerebral perfusion (RCP) during pediatric open heart surgery. Between January 1, 2004 and September 30, 2012, 1250 children with congenital cardiac defect underwent corrective operation with the DHCA or RCP technique in the Shanghai Children's Medical Center. Of them, 947 cases underwent the operation with the aid of DHCA (DHCA group), and 303 cases with RCP (RCP group). The mean DHCA time was 30.64±15.81 (7-63) minutes and mean RCP time was 36.18±12.86 (10-82) minutes. The mortality rate was 7.18% (68/947) and 6.60% (20/30) in two groups, respectively. The postoperative incidences of temporary and permanent neurological dysfunction were 6.23% (59/947) in the DHCA group and 2.64% (8/303) in the RCP group (p<0.01). The incidence of other complications such as low cardiac output, renal dysfunction, and lung issues are similar in both groups. RCP is a reliable technique for cerebral protection and it facilitates time-consuming corrected procedures for complex congenital cardiac defect repair procedures.

Modern temperature management in aortic arch surgery: the dilemma of moderate hypothermia

Arch surgery is undoubtedly among the most technically and strategically challenging endeavours in aortic surgery, requiring thorough understanding not only of cardiovascular physiology, but also in particular, of neurophysiology (cerebral and spinal cord), and is still associated with significant mortality and morbidity. In the late 1980s, when deep hypothermic circulatory arrest (HCA) had gained widespread acceptance as the standard approach for arch surgery, antegrade selective cerebral perfusion (SCP), as an adjunct to deep HCA, began its triumphal march, offering excellent neuroprotection and improved overall outcome. This encouraged the use of antegrade SCP in combination with steadily increasing body core temperatures--a trend culminating in the progressive advocation of moderate-to-mild temperatures up to 35 °C, and even normothermia. The impetus for progressive temperature elevation was the limitation of adverse effects of profound hypothermia and the most welcome side effect of significantly shorter cooling and rewarming periods on cardiopulmonary bypass (CPB), and thereby, potentially, the alleviation of the systemic inflammatory response and, in particular, the risk of severe postoperative bleeding (and other organ dysfunctions). The safe limits of prolonged distal circulatory arrest, particularly with regard to the ischaemic tolerance of the viscera and the spinal cord, have not yet been clearly defined. Adverse outcomes due to inappropriate temperature management (core temperatures too high for the required duration of distal arrest) are probably highly underreported. Complications historically associated with hypothermia, namely excessive bleeding, are possibly overestimated. Trading effective neuroprotection and excellent outcomes for the risk of prolonged 'warm' distal ischaemia might constitute a significant step back, jeopardizing visceral and, in particular, spinal cord integrity, with unpredictable consequences for long-term outcome and quality of life, particularly affecting those in need of more complex surgery or with previous neurological deficits.

Long-term results after proximal thoracic aortic redo surgery

OBJECTIVE

To evaluate early and mid-term results in patients undergoing proximal thoracic aortic redo surgery.

METHODS

We analyzed 60 patients (median age 60 years, median logistic EuroSCORE 40) who underwent proximal thoracic aortic redo surgery between January 2005 and April 2012. Outcome and risk factors were analyzed.

RESULTS

In hospital mortality was 13%, perioperative neurologic injury was 7%. Fifty percent of patients underwent redo surgery in an urgent or emergency setting. In 65%, partial or total arch replacement with or without conventional or frozen elephant trunk extension was performed. The preoperative logistic EuroSCORE I confirmed to be a reliable predictor of adverse outcome- (ROC 0.786, 95%CI 0.64-0.93) as did the new EuroSCORE II model: ROC 0.882 95%CI 0.78-0.98. Extensive individual logistic EuroSCORE I levels more than 67 showed an OR of 7.01, 95%CI 1.43-34.27. A EuroSCORE II larger than 28 showed an OR of 4.44 (95%CI 1.4-14.06). Multivariate logistic regression analysis identified a critical preoperative state (OR 7.96, 95%CI 1.51-38.79) but not advanced age (OR 2.46, 95%CI 0.48-12.66) as the strongest independent predictor of in-hospital mortality. Median follow-up was 23 months (1-52 months). One year and five year actuarial survival rates were 83% and 69% respectively. Freedom from reoperation during follow-up was 100%.

CONCLUSIONS

Despite a substantial early attrition rate in patients presenting with a critical preoperative state, proximal thoracic aortic redo surgery provides excellent early and mid-term results. Higher EuroSCORE I and II levels and a critical preoperative state but not advanced age are independent predictors of in-hospital mortality. As a consequence, age alone should no longer be regarded as a contraindication for surgical treatment in this particular group of patients.

Combination treatment of hypothermia and mesenchymal stromal cells amplifies neuroprotection in primary rat neurons exposed to hypoxic-ischemic-like injury in vitro: role of the opioid system

This study was designed to reveal the therapeutic regimen and mechanism of action underlying hypothermia treatment in combination with stem cell transplantation for ameliorating neonatal hypoxic-ischemic-like injury. Primary rat neurons were exposed to oxygen-glucose deprivation (OGD), which produced hypoxic-ischemic-like injury in vitro, then incubated at 25°C (severe hypothermia), 34°C (moderate hypothermia), and 37°C (normothermia) with or without subsequent co-culture with mesenchymal stromal cells (MSCs). Combination treatment of moderate hypothermia and MSCs significantly improved cell survival and mitochondrial activity after OGD exposure. The exposure of delta opioid human embryonic kidney cells (HEK293) to moderate hypothermia attenuated OGD-mediated cell alterations, which were much more pronounced in HEK293 cells overexpressing the delta opioid receptor. Further, the addition of delta opioid peptide to 34°C hypothermia and stem cell treatment in primary rat neurons showed synergistic neuroprotective effects against OGD which were significantly more robust than the dual combination of moderate hypothermia and MSCs, and were significantly reduced, but not completely abolished, by the opioid receptor antagonist naltrexone altogether implicating a ligand-receptor mechanism of neuroprotection. Further investigations into non-opioid therapeutic signaling pathways revealed growth factor mediation and anti-apoptotic function accompanying the observed therapeutic benefits. These results support combination therapy of hypothermia and stem cells for hypoxic-ischemic-like injury in vitro, which may have a direct impact on current clinical trials using stand-alone hypothermia or stem cells for treating neonatal encephalopathy.