Deep hypothermic circulatory arrest and antegrade selective cerebral perfusion during ascending aorta-hemiarch replacement: a retrospective comparative study

Study on risk factors and treatment strategies of hypoxemia after acute type a aortic dissection surgery

Acute type A aortic dissection is a life-threatening cardiovascular disease characterized by rapid onset and high mortality. Emergency surgery is the preferred and reliable treatment option. However, postoperative complications significantly impact patient prognosis. Hypoxemia, a common complication, poses challenges in clinical treatment, negatively affecting patient outcomes and increasing the risk of mortality. Therefore, it is crucial to study and comprehend the risk factors and treatment strategies for hypoxemia following acute type A aortic dissection to facilitate early intervention.

Risk Factors for Stroke Development After Thoracic Aortic Surgery

OBJECTIVES

Stroke after thoracic aortic surgery is a complication that is associated with poor outcomes. The aim is to characterize the intraoperative risk factors for stroke development.

DESIGN

A retrospective analysis.

SETTING

Tertiary, high-volume cardiac surgery center.

PARTICIPANTS

Patients who had surgical repair of thoracic aortic diseases from January 1, 2017, through December 31, 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 704 patients were included, of whom 533 had ascending aortic aneurysms, and 171 had type A aortic dissection. The incidence of postoperative stroke was 4.5% (95% CI 2.9%-6.6%) for ascending aortic aneurysms compared with 12.3% (95% CI 7.8%-18.16%) in type-A aortic dissections. Patients who developed postoperative strokes had significantly lower intraoperative hemoglobin median (7.5 gm/dL [IQR 6.8-8.6] v 8.55 gm/dL [IQR 7.3-10.0]; p < 0.001). The median cardiopulmonary bypass time was 185 minutes (IQR 136-328) in the stroke group versus 156 minutes (IQR 113-206) in the nonstroke group (p = 0.014). Circulatory arrest was used in 57.8% versus 38.5% of the nonstroke patients (p = 0.017). The initial temperature after leaving the operating room was lower, with a median of 35.0°C (IQR 34-35.92) in the stroke group versus 35.5°C (IQR 35-36) in the nonstroke cohort (p = 0.021).

CONCLUSIONS

This single-center study highlighted the potential importance of intra-operative factors in preventing stroke. Lower hemoglobin, longer duration of cardiopulmonary bypass, deep hypothermic circulatory arrest, and postoperative hypothermia are potential risk factors for postoperative stroke. Further studies are needed to prevent this significant complication in patients with thoracic aortic diseases.

Central aortic versus axillary artery cannulation for aortic arch surgery

Objective

Central aortic cannulation for aortic arch surgery has become more popular over the last decade; however, evidence comparing it with axillary artery cannulation remains equivocal. This study compares outcomes of patients who underwent axillary artery and central aortic cannulation for cardiopulmonary bypass during arch surgery.

Methods

A retrospective review of 764 patients who underwent aortic arch surgery at our institution between 2005 and 2020 was performed. The primary outcome was failure to achieve uneventful recovery, defined as having experienced at least 1 of the following: in-hospital mortality, stroke, transient ischemic attack, bleeding requiring reoperation, prolonged ventilation, renal failure, mediastinitis, surgical site infection, and pacemaker or implantable cardiac defibrillator implantation. Propensity score matching was used to account for baseline differences across groups. A subgroup analysis of patients undergoing surgery for aneurysmal disease was performed.

Results

Before matching, the aorta group had more urgent or emergency operations (P = .039), fewer root replacements (P < .001), and more aortic valve replacements (P < .001). After successful matching, there was no difference between the axillary and aorta groups in failure to achieve uneventful recovery, 33% versus 35% (P = .766), in-hospital mortality, 5.3% versus 5.3% (P = 1), or stroke, 8.3% versus 5.3% (P = .264). There were more surgical site infections in the axillary group, 4.8% versus 0.4% (P = .008). Similar results were seen in the aneurysm cohort with no differences in postoperative outcomes between groups.

Conclusions

Aortic cannulation has a safety profile similar to that of axillary arterial cannulation in aortic arch surgery.

Cerebral Perfusion and Neuromonitoring during Complex Aortic Arch Surgery: A Narrative Review

Complex ascending and aortic arch surgery requires the implementation of different cerebral protection strategies to avoid or limit the probability of intraoperative brain damage during circulatory arrest. The etiology of the damage is multifactorial, involving cerebral embolism, hypoperfusion, hypoxia and inflammatory response. These protective strategies include the use of deep or moderate hypothermia to reduce the cerebral oxygen consumption, allowing the toleration of a variable period of absence of cerebral blood flow, and the use of different cerebral perfusion techniques, both anterograde and retrograde, on top of hypothermia, to avoid any period of intraoperative brain ischemia. In this narrative review, the pathophysiology of cerebral damage during aortic surgery is described. The different options for brain protection, including hypothermia, anterograde or retrograde cerebral perfusion, are also analyzed, with a critical review of the advantages and limitations under a technical point of view. Finally, the current systems of intraoperative brain monitoring are also discussed.

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.

Cerebral protection using deep hypothermic circulatory arrest versus retrograde cerebral perfusion for aortic hemiarch reconstruction

BACKGROUND

With evolutions in technique, recent data encourage the use of cerebral perfusion during aortic arch repair. However, a randomized data have demonstrated higher rates of neurologic injury according to MRI lesions using antegrade cerebral perfusion during hemiarch reconstruction.

METHODS

This was a retrospective review of two institutional aortic center databases to identify adult patients who underwent aortic hemiarch reconstruction for elective aortic aneurysm or acute type A aortic dissection. Patients were stratified according to cerebral protection method: (1) deep hypothermic circulatory arrest (DHCA) group versus (2) DHCA/retrograde cerebral perfusion (RCP) group.

RESULTS

A total of 320 patients and 245 patients underwent hemiarch reconstruction for aortic aneurysm electively and aortic dissection, respectively. In aneurysmal pathology, the DHCA group included 133 patients and the DHCA/RCP group included 187 patients. Operative mortality was 0.8% in the DHCA group and 2.7% in the DHCA/RCP group (p = 0.41). Kaplan-Meier survival estimates revealed comparable 2-year survival (p = 0.14). In dissection, 43 patients and 202 patients were included in the DHCA group and the DHCA/RCP group, respectively. Operative mortality was equivalent between the two groups (11.6% in the DHCA group and 9.4% in the DHCA/RCP group, p = 0.58). Long-term survival was similar at 2 years between the groups (p = 0.06). Multivariable analysis showed cerebral perfusion strategy was not associated with the composite outcome of operative mortality and stroke.

CONCLUSIONS

In treating both elective and acute ascending aortic pathologies with hemiarch reconstruction, both DHCA alone or in combination with RCP yield comparable results.

Risk factors for impaired neurological outcome after thoracic aortic surgery

Background

We aimed to identify risk factors for an impaired postoperative neurological outcome after thoracic aortic surgery.

Methods

Data from all patients undergoing thoracic aortic surgery between 2010 and 2020 at our institution were collected and analyzed retrospectively. Logistic regression analysis was used to identify independent risk factors for permanent postoperative neurological deficit (ND) (stroke), which was defined as a ND lasting at least seven days.

Results

Thoracic aortic surgery was performed in 1,334 patients. Of these, 286 (21.4%) underwent emergency surgery. The mean EuroSCORE II was 8.6±10.1. A perioperative stroke occurred in 94 patients (7.0%). Of all strokes, 62.8% (n=59) were considered of embolic and 24.5% (n=23) of hemodynamic origin. In elective procedures, stroke rates ranged from 0.5% after valve-sparing root replacement to 8.1% after arch surgery. Adjusted logistic regression identified advanced age [>70 years; odds ratio (OR), 1.83; P=0.009], acute type A dissection (ATAD) (OR, 1.69; P=0.0495), aortic arch surgery (OR, 3.24; P<0.001), concomitant coronary artery bypass grafting (CABG) (OR, 2.19; P=0.005), and high extracorporeal circulation (ECC) time (>230 min; OR, 1.70; P=0.034) as independent risk factors for all strokes. Secondary endpoint analyses revealed that risk factors for hemodynamic stroke were arch surgery, advanced age (>70 years), atherosclerosis, and ATAD. Risk factors for embolic stroke were arch surgery, concomitant CABG and preoperative cerebral malperfusion.

Conclusions

Identified independent risk factors for all strokes were advanced age, ATAD, arch surgery, concomitant CABG, and high ECC time. Hemodynamic and embolic strokes show distinct risk profiles.

Normothermic frozen elephant trunk: our experience and literature review

BACKGROUND AND OBJECTIVE

The frozen elephant trunk (FET) technique has undoubtable advantages in treating complex and extensive disease of the aortic arch and the thoracic descending aorta. Despite several improvements in cardiopulmonary bypass conduction and surgical strategy, operative times and the institution of systemic circulatory arrest remain the main determinants of early mortality, cerebral/spinal cord injury and visceral organs dysfunction. We have conducted this review to highlight the recent technical advances in arch and FET surgery aiming at the reduction/avoidance of systemic circulatory arrest, and their impact on early outcomes.

METHODS

A literature search (from origin to January 2022), limited to publications in English, was performed on online platforms and database (PubMed, Google, ResearchGate). After a further review of associated or similar papers, we found 4 experiences, described by 11 peer-reviewed published papers, which focused on minimising or avoiding systemic circulatory arrest during total arch replacement plus stenting of the descending thoracic aorta.

KEY CONTENT AND FINDINGS

Recent experiences reported the use of an antegrade endoaortic balloon, advanced and inflated into the stent graft, to provide an early systemic reperfusion soon after the deployment of the stented portion of the FET prosthesis and minimize the circulatory arrest time (down to a mean of 5 minutes), thus avoiding the need of moderate or deep hypothermia (mean systemic temperature 28-30 °C) while allowing a complete arch and FET repair. Our approach, based on off-pump retrograde vascular stent graft deployment in distal arch/descending thoracic aorta, and the use of a retrograde endoballoon, allows the repair of extensive aortic pathologies during uninterrupted normothermic cerebral and lower body perfusion.

CONCLUSIONS

The use of endoballoon occlusion has emerged in recent years as a safe and effective strategy to allow distal perfusion during FET repair. This technique minimizes or avoids the detrimental effects of hypothermia and systemic circulatory arrest and significantly reduces the operative times.

The New York experience of open arch surgery

BACKGROUND

Aortic arch repair has undergone constant evolution since its inception with improving outcomes. A sizeable number of competing techniques and strategies have been described, with no single optimal method endorsed by the surgical community. We describe our experience with open aortic arch repair in a high-volume center.

METHODS

We queried our aortic database for consecutive patients undergoing aortic arch repair from 1997-2021. Those undergoing hemiarch repair were compared to those undergoing total arch repair. Outcomes were compared using multivariate analysis.

RESULTS

Of 1308 patients undergoing aortic arch repair, 953 underwent hemiarch repair and 355 underwent total arch repair. The median age was 69 [interquartile ratio 58-76] and 61.7% were men. Hemiarch patients more frequently hade aortic dissection (28.5 vs 11.8%, P < 0.001) and urgent or emergent procedure status (45.1 vs 30.4%, P < 0.001). Overall operative mortality was 2.7% and significantly higher in the hemiarch group (3.5 vs 0.6%, P=0.007). No difference in the incidence of major adverse events (MAE) including myocardial infarction, cerebrovascular accident, new need for dialysis, re- exploration for bleeding, and tracheostomy was found between the two groups. Multivariate analysis found diabetes, urgent or emergent procedure status, preoperative renal dysfunction, New York Heart Association class III/IV symptoms, and connective tissue disease to be independent predictors of MAE.

CONCLUSIONS

Retrograde cerebral perfusion with deep hypothermic circulatory arrest is safe and effective, with no appreciable difference in neurologic outcomes when comparing hemiarch to total arch strategies. Rates of mortality and MAE compare favorably with strategies utilizing antegrade cerebral perfusion.

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.

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.

Mild hypothermic circulatory arrest with selective cerebral perfusion in open arch surgery

Background

This study aimed to evaluate whether the use of mild hypothermic circulatory arrest (HCA) with selective cerebral perfusion (SCP) in open arch procedure provides comparable perioperative results to moderate HCA for patients with dissected or degenerative arch pathologies.

Methods

Between January 2017 and September 2020, a total of 88 consecutive patients (mean age 47±11 years, 71 males) underwent open arch repair under a single surgeon at our institution with mild or moderate systemic hypothermia assisted by unilateral or bilateral SCP. Patients were divided into groups according to the nasopharyngeal temperature at the beginning of HCA: a moderate HCA group (n=47, 53.4%) and a mild HCA group (n=41, 46.6%). The postoperative mortality, morbidity, and visceral organ functions between these groups were analyzed retrospectively.

Results

Compared to the moderate HCA group, the mild HCA group had a significantly higher core temperature (nasopharynx: 24.4±0.8 vs. 28.5±2, P<0.001; bladder 25.9±0.9 vs. 30±1.2, P<0.001), and the incidence of major adverse events (MAE) in this group was markedly lower (21.3% vs. 4.9%, P=0.031). No differences were identified between the two groups refer to in-hospital mortality, permanent neurological deficit (PND), temporary neurological deficit (TND), and paraplegia (8.5% vs. 2.4%, P=0.366; 8.5% vs. 0, P=0.120; 6.4% vs. 7.3%, P=1.0; 4.3% vs. 2.4%, P=1.0, respectively). In the moderate HCA group, 6 patients (12.8%) developed acute renal failure needing replacement therapy, which did not occur in the mild HCA group (P=0.028). The duration of ventilator support and intensive care unit stay was shorter in the mild HCA group, as well as a decreased volume of drainage during the first 24 h and reduced platelet transfusion.

Conclusions

The preliminary results of the mild HCA group with SCP applied in open arch repair, mainly in total arch replacement (TAR) and stented elephant trunk (SET) implantation for aortic dissection, were satisfactory. Furthermore, comparable inferior outcomes were obtained with mild HCA compared with that of the conventional moderate HCA strategy. These encouraging surgical and postoperative results favor this more aggressive hypothermia strategy in open arch repair.

Different hypothermic and cerebral perfusion strategies in extended arch replacement for acute type a aortic dissection: a retrospective comparative study

BACKGROUND

The optimal hypothermic level in total arch replacement with stented elephant trunk implantation for acute type A aortic dissection (aTAAD) has not been established, and the superiority of unilateral or bilateral cerebral perfusion remains a controversial issue. Therefore, we evaluated the application of moderate hypothermic circulatory arrest (MHCA) with a core temperature of 29 °C and bilateral selective antegrade cerebral perfusion in aTAAD treated by total arch replacement with stented elephant trunk implantation.

METHODS

From July 2019 to January 2020, 25 aTAAD patients underwent total arch replacement with stented elephant trunk implantation via MHCA (29 °C) and bilateral selective antegrade cerebral perfusion (modified group). Thirty-six patients treated by the same procedure with MHCA (25 °C) and unilateral selective antegrade cerebral perfusion during this period were selected as controls.

RESULTS

There were no differences between the two groups of patients in terms of age, sex, incidence of hypertension, malperfusion, and pericardial effusion, although the incidence of cardiac tamponade was higher in the modified group (control 2.8%, modified 20%; P = 0.038). The lowest mean circulatory arrest temperature was 24.6 ± 0.9 °C in the control group, and 29 ± 0.8 °C in the modified group (P <  0.001). In-hospital mortality was 4.9% (3/61) for the entire cohort (control 8.3%, modified 0; P = 0.262). The incidence of permanent neurologic deficit was 4.9% (control 8.3%, modified 0; P = 0.262). There were no significant differences in the occurrence of temporary neurological deficit, renal failure, and paraplegia between groups. The rate of major adverse events in the modified group was lower (30.6% vs. 4%, P = 0.019). A shorter duration of ventilation and ICU stay was identified in the modified group, as well as a reduced volume of drainage within the first 48 h and red blood cell transfusion.

CONCLUSIONS

The early results of MHCA (29 °C) and bilateral selective antegrade cerebral perfusion applied in total arch replacement with stented elephant trunk implantation for aTAAD were acceptable, providing similar inferior cerebral and visceral protection compared with that of the conventional strategy. A higher core temperature may account for the shorter duration of ventilation and ICU stay, as well as a reduced volume of drainage and red blood cell transfusion.

Computational fluid dynamics of a novel perfusion strategy during hybrid thoracic aortic repair

BACKGROUND AND AIM

To mitigate the risk of perioperative neurological complications during frozen elephant trunk procedures, we aimed to computationally evaluate the effects of direct cerebral perfusion strategy through a left carotid-subclavian bypass on hemodynamics in a patient-specific thoracic aorta model.

METHODS

Between July 2016 and March 2019, 11 consecutive patients underwent frozen elephant trunk operation using the left carotid-subclavian bypass with a side graft anastomosis and right-axillary cannulation for systemic and brain perfusion. A multiscale model realized coupling three-dimensional computational fluid dynamics was developed and validated with in vivo data. Model comparison with direct antegrade cannulation of all epiaortic vessels was performed. Wall shear stress, wall shear stress spatial gradient, and localized normalized helicity were selected as hemodynamic indicators. Four cerebral perfusion flows were tested (6 to 15 mL/kg/min).

RESULTS

Direct cerebral perfusion of the left subclavian bypass resulted in higher flow rates with augmented speeds in all epiaortic vessels in comparison with traditional perfusion model. At the level of the left vertebral artery (LVA), a speed of 22.5 vs 21 mL/min and mean velocity of 3.07 vs 2.93 cm/s were registered, respectively. With a cerebral perfusion flow of 15 mL/kg, lower LVA wall shear stress (1.596 vs 2.030 N/m² ), and wall shear stress gradient (1445 vs 5882 N/m³ ) were observed. A less disturbed flow considering the localized normalized helicity was documented. No patients experienced neurological/spinal cord damages.

CONCLUSIONS

Direct perfusion of a left carotid bypass proved to be cerebroprotective, resulting in a more physiological and stable anterior and posterior cerebral perfusion.

Intermittent upper and lower body perfusion during circulatory arrest is safe for aortic repair

Introduction:

We report our initial surgical experience of intermittent upper and lower body retrograde perfusion during aortic repair under circulatory arrest.

Methods:

Between 2007 and 2015, 148 consecutive patients underwent surgical aortic repair using moderate hypothermic circulatory arrest with intermittent upper and lower body retrograde perfusion.

Results:

All patients underwent ascending aorta replacement; eight had hemiarch replacement (5.4%) and 92 had aortic root surgery (62.2%). Twenty-nine patients (19.6%) had re-operations and 60 patients (40.5%) had concomitant procedures. The mean duration of circulatory arrest was 23.2 ± 5.4 minutes (range 13-48 minutes). Hospital length of stay was 11.3 ± 16.9 days (median 7.0 days; interquartile range [IQR] 6 days). Complications included death in 0.7%, stroke in 3.4%, respiratory failure in 12.8%, renal replacement therapy in 2.0% and re-exploration for bleeding in 0.7%. Peak renal and hepatic biomarkers were: creatinine 1.2 ± 0.3 mg/dL, aspartate aminotransferase (AST) 291 ± 1112 U/L (IQR 91.8 U/L), alanine aminotransferase (ALT) 212 ± 924 U/L (IQR 43.0 U/L) and total bilirubin 1.2 ± 0.9 mg/dL. Peak lactate was 5.0 ± 3.3 mmol/L (IQR 3.3 mmol/L) and the mean time to normalization (<2 mmol/L) was 14.3 ± 14.0 hours.

Conclusions:

Intermittent upper and lower body retrograde perfusion during circulatory arrest is safe for aortic repair, resulting in low morbidity and mortality. There were only modest rises in hepatic and renal injury biomarkers as well as the rapid clearance of lactate. These findings support the continued study of this technique to reduce end-organ dysfunction during circulatory arrest, including expansion to patients with longer circulatory arrest duration and a direct comparison with conventional circulatory arrest without retrograde upper and lower body perfusion.

Chipmunk Brain Is Resistant to Injury from Deep Hypothermic Circulatory Arrest During Cardiopulmonary Bypass

Chipmunk as a food-storing hibernator naturally undergoes hibernation that is linked to great changes in systemic physiology and could protect the central nervous system during drastically reduced cerebral blood flow and low temperature in hibernation. Deep hypothermic circulatory arrest (DHCA) is associated with neurological dysfunction. We aim to test whether the euthermic chipmunk is resistant to injury from DHCA. Sprague-Dawley (SD) rats were used in a positive control. Ten euthermic chipmunks and 10 rats were subjected to 60-minute DHCA. Sham rats and chipmunks received cannulations. The blood samples after surgery were extracted to measure the tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) level. The levels of opioid receptor delta 1 (OPRD1), mature brain-derived neurotrophic factor (m-BDNF), precursor of BDNF (pro-BDNF), TrkB, GRB2, Erk, p-Erk, P38, Bcl-2, P75NTR, TRAF6, JNK, P53, Bax, and Caspase3 of the hippocampus were analyzed at 24 hours after surgery. The brain of chipmunks and rats were fixed for histopathological assessment. In the DHCA rat group, the levels of TNF-α and IL-6 were greater (p < 0.05) compared with DHCA chipmunks. In the DHCA chipmunk group, the levels of OPRD1, mature BDNF/pro-BDNF, TrkB-FL/TrkB-T1, Bcl-2, and p-Erk/Erk of hippocampus were higher than DHCA rats. The levels of GRB2, P75NTR, TRAF6, P53, Bax, and Caspase3 in DHCA chipmunks were lower than DHCA rats. The histopathological assessment showed that the injury in DHCA rat group was more severe than the DHCA chipmunk group. Euthermic chipmunks were greatly tolerant to global cerebral injury during DHCA. Different isoforms of BDNF might be involved in the resistant strategy.

Selective Cerebral Perfusion with the Open Proximal Technique during Descending Thoracic or Thoracoabdominal Aortic Repair: An Option of Choice to Reduce Neurologic Complications

PURPOSE

Selective cerebral perfusion with the open proximal technique for thoracoabdominal aortic repair has not been conclusively validated because of its procedural complexity and unreliability. We report the clinical outcomes, particularly the cerebroneurological complications, of an open proximal procedure using selective cerebral perfusion.

METHODS

A retrospective chart review identified 30 patients between 2007 and 2015 who underwent aortic repair through left lateral thoracotomy with selective cerebral perfusion, established through endoluminal brachiocephalic and left carotid artery and retrograde left axillary artery.

RESULTS

The mean durations of the open proximal procedure and cerebral ischemia (the duration of the open proximal procedure minus the duration of selective cerebral perfusion) were 110.3 ± 40.1 min and 24.8 ± 13.0 min, respectively. There were two cases (7%) of permanent neurologic dysfunction (PND) but no in-hospital deaths. Multivariate analysis identified the duration of cerebral ischemia as an independent risk factor for neurologic complications including temporary neurologic dysfunction (TND; odds ratio (OR): 1.13; p = 0.007), but no correlation was found between selective cerebral perfusion duration and neurologic complications.

CONCLUSION

Despite the relatively long duration of the open proximal procedure, selective cerebral perfusion has a potential to protect against cerebral complications during thoracic aortic repair through a left lateral thoracotomy.

Abdominal organ protection strategy for aortic arch aneurysm surgery

INTRODUCTION

Body temperature maintained during open distal anastomosis in patients who undergo aortic surgery has been showing an upward trend; however, a higher temperature may increase visceral organ and spinal cord injury. Distal perfusion may reduce abdominal organ injury, especially acute kidney injury (AKI).

METHODS

From 2009 to 2016, 56 patients who underwent ascending aortic and/or aortic arch surgery were enrolled. Open distal anastomosis was performed using one of three protection strategies: 1) systemic temperature of 25°C followed by selective cerebral perfusion (SCP) with lower body circulatory arrest (Group CA25, n=27); 2) systemic temperature of 28°C followed by SCP with lower body circulatory arrest (Group CA28, n=4); and 3) systemic temperature of 28°C followed by SCP with distal aortic perfusion (Group DP, n=25).

RESULTS

During the postoperative course, levels of blood urea nitrogen, creatinine, liver enzymes, lactate dehydrogenase and lactate in Groups CA28 and CA25 were significantly higher than those in Group DP. AKI defined by the AKI Network occurred in 28 cases (50%) and 3 cases required permanent hemodialysis. AKI was significantly higher in Groups CA25 and CA28 than in Group DP (p=0.026). Mid-term follow-up showed that patients who developed postoperative AKI were more likely to suffer from cardiovascular events.

CONCLUSIONS

Distal perfusion during open distal anastomosis reduced kidney and liver injury after thoracic aortic surgery despite an increased body temperature of up to 28°C. This strategy may be useful to prevent AKI, liver dysfunction, the need for hemodialysis and multiple organ failure and could improve mid-term results.

Varying Evidence on Deep Hypothermic Circulatory Arrest in Thoracic Aortic Aneurysm Surgery

Cardiovascular surgeons have long debated the safe duration of deep hypothermic circulatory arrest during thoracic aortic aneurysm surgery. The rationale for using adjunctive cerebral perfusion (or not) is to achieve the best technical aortic repair with the lowest risk of morbidity and death. In this literature review, we highlight the debates surrounding these issues, evaluate the disparate findings on deep hypothermic circulatory arrest durations and temperatures, and consider the usefulness of adjunctive perfusion.

An innovative arch-first surgical procedure under moderate hypothermia for acute type A aortic dissection

BACKGROUND

We hypothesized that the arch-first procedure without extra devices under moderate-to-mild systemic hypothermia during acute type A aortic dissection is safe and efficient and will improve patient outcome compared with the standard total arch replacement technique.

METHODS

From December 2014 to February 2017, 89 patients were enrolled in this study, 52 of whom underwent conventional deep hypothermic circulatory arrest (DHCA, 24.2±0.71 °C) using the antegrade cerebral perfusion surgical procedure (Group A) and 37 of whom underwent the "arch-first" technique with moderate (27.4±1.1 °C) systemic hypothermia during antegrade cerebral perfusion (Group B). The clinical data, surgical and postoperative data, complications, and mortality of the two groups were analyzed.

RESULTS

The cardiopulmonary bypass (171.3±40.0 min) and awakening time (7.0 hours) was significantly decreased in Group B. Two patients died 30 d after surgery (5.4%, two of 37) in Group B. The incidence of transient neurologic deficit (2.7%) and distal organ complications (5.4%) was lower in Group B.

CONCLUSIONS

In patients with acute type A aortic dissection involving the arch, the innovative arch-first surgical procedure could provide feasible and safe treatment outcomes, which brings us closer to the goal of performing surgery with moderate-to-mild systemic hypothermia with better cerebral, distal organ, and survival outcomes.

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.

The impact of temperature in aortic arch surgery patients receiving antegrade cerebral perfusion for >30 minutes: How relevant is it really?

OBJECTIVE

We examined the early outcomes and the long-term survival associated with different degrees of hypothermia in patients who received antegrade cerebral perfusion (ACP) for >30 minutes.

METHODS

During a 10-year period, 544 consecutive patients underwent proximal and total aortic arch surgery and received ACP for >30 minutes and 1 of 3 levels of hypothermia: deep (14.1°C-20°C; n = 116 [21.3%]), low-moderate (20.1°C-23.9°C; n = 262 [48.2%]), and high-moderate (24°C-28°C; n = 166 [30.5%]). A variable called "predicted temperature" was used in propensity-score analysis. Multivariate analysis was done to evaluate the effect of actual temperature on outcomes.

RESULTS

The operative mortality rate was 12.5% (n = 68) overall and was 15.5%, 11.8%, and 11.5% in the deep, low-moderate, and high-moderate hypothermia patients, respectively (P = .54). The persistent stroke rate was 6.6% overall and 12.2%, 4.6%, and 6.0% in these 3 groups, respectively (P = .024 on univariate analysis). On multivariate analysis, actual temperature was not associated with mortality, but lower temperatures predicted persistent stroke and reoperation for bleeding. In the propensity-matched subgroups, the patients with predicted deep hypothermia had (nonsignificantly) greater rates of persistent stroke (12.2% vs 4.9%; relative risk, 1.08; 95% CI, 0.87-1.15) and reoperation for bleeding (14.6% vs 2.4%; relative risk, 1.14; 95% CI, 0.87-1.15) than the patients with predicted moderate hypothermia. On long-term follow-up (mean duration, 5.12 years), 4- and 8-year survival rates were 62.3% and 55.7% in the deep hypothermia group and 75.4% and 74.2% in the moderate hypothermia group (P = .0015).

CONCLUSIONS

In proximal and arch operations involving ACP for >30 minutes, greater actual temperatures were associated with less stroke and reoperation for bleeding. There were no significant differences among the predicted hypothermia levels, although a trend toward a higher rate of adverse events was noticed in the deep hypothermia group. Long-term survival was better in the moderate hypothermia group.

Optimal temperature management in aortic arch operations

Hypothermic circulatory arrest is a critical component of aortic arch procedures, without which these operations could not be safely performed. Despite the use of hypothermia as a protective adjunct for organ preservation, aortic arch surgery remains complex and is associated with numerous complications despite years of surgical advancement. Deep hypothermic circulatory arrest affords the surgeon a safe period of time to perform the arch reconstruction, but this interruption of perfusion comes at a high clinical cost: stroke, paraplegia, and organ dysfunction are all potential-associated complications. Retrograde cerebral perfusion was subsequently developed as a technique to improve upon the rates of neurologic dysfunction, but was done with only modest success. Selective antegrade cerebral perfusion, on the other hand, has consistently been shown to be an effective form of cerebral protection over deep hypothermia alone, even during extended periods of circulatory arrest. A primary disadvantage of using deep hypothermic circulatory arrest is the prolonged bypass times required for cooling and rewarming which adds significantly to the morbidity associated with these procedures, especially coagulopathic bleeding and organ dysfunction. In an effort to mitigate this problem, the degree of hypothermia at the time of the initial circulatory arrest has more recently been reduced in multiple centers across the globe. This technique of moderate hypothermic circulatory arrest in combination with adjunctive brain perfusion techniques has been shown to be safe when performing aortic arch operations. In this review, we will discuss the evolution of these protection strategies as well as their relative strengths and weaknesses.

Goal-directed-perfusion in neonatal aortic arch surgery

Reduction of mortality and morbidity in congenital cardiac surgery has always been and remains a major target for the complete team involved. As operative techniques are more and more standardized and refined, surgical risk and associated complication rates have constantly been reduced to an acceptable level but are both still present. Aortic arch surgery in neonates seems to be of particular interest, because perfusion techniques differ widely among institutions and an ideal form of a so called "total body perfusion (TBP)" is somewhat difficult to achieve. Thus concepts of deep hypothermic circulatory arrest (DHCA), regional cerebral perfusion (RCP/with cardioplegic cardiac arrest or on the perfused beating heart) and TBP exist in parallel and all carry an individual risk for organ damage related to perfusion management, chosen core temperature and time on bypass. Patient safety relies more and more on adequate end organ perfusion on cardiopulmonary bypass, especially sensitive organs like the brain, heart, kidney, liver and the gut, whereby on adequate tissue protection, temperature management and oxygen delivery should be visualized and monitored.

How to Perfuse: Concepts of Cerebral Protection during Arch Replacement

Arch surgery remains undoubtedly among the most technically and strategically challenging endeavors in cardiovascular surgery. Surgical interventions of thoracic aneurysms involving the aortic arch require complete circulatory arrest in deep hypothermia (DHCA) or elaborate cerebral perfusion strategies with varying degrees of hypothermia to achieve satisfactory protection of the brain from ischemic insults, that is, unilateral/bilateral antegrade cerebral perfusion (ACP) and retrograde cerebral perfusion (RCP). Despite sophisticated and increasingly individualized surgical approaches for complex aortic pathologies, there remains a lack of consensus regarding the optimal method of cerebral protection and circulatory management during the time of arch exclusion. Many recent studies argue in favor of ACP with various degrees of hypothermic arrest during arch reconstruction and its advantages have been widely demonstrated. In fact ACP with more moderate degrees of hypothermia represents a paradigm shift in the cardiac surgery community and is widely adopted as an emergent strategy; however, many centers continue to report good results using other perfusion strategies. Amidst this important discussion we review currently available surgical strategies of cerebral protection management and compare the results of recent European multicenter and single-center data.

Prolonged postoperative respiratory support after proximal thoracic aortic surgery: Is deep hypothermic circulatory arrest a risk factor?

PURPOSE

In addition to the pulmonary risks associated with cardiopulmonary bypass, thoracic aortic surgery using deep hypothermic circulatory arrest (DHCA) may subject the lungs to further injury. However, this topic has received little investigation to date.

MATERIALS AND METHODS

A prospective cohort review was performed on all patients undergoing proximal thoracic aortic surgery with (n = 478) and without (n = 135) DHCA between July 2005 and February 2013 at a single institution. The primary outcome was prolonged postoperative respiratory support (PPRS), defined as any of the following: >1 day of mechanical ventilation at either fraction of inspired oxygen >0.4 and/or positive end-expiratory pressure >5 mm Hg, >2 days of supplemental O2 requirement of at least 2.5 L/min, or discharge with new O2 requirement. Independent risk factors for PPRS were identified using multivariable logistic regression.

RESULTS

Postoperative respiratory support was required in 100 patients (20.9%) with and 30 patients (22.2%) without DHCA (P = .74). Independent predictors of PPRS after proximal aortic surgery included the following: age, diabetes, history of stroke, preoperative creatinine, American Society of Anesthesiologists class 4, redo-sternotomy, total arch replacement, and transfusion requirement. Use of DHCA was not an independent risk factor for PPRS in the entire cohort. Subanalysis of only DHCA patients revealed that longer DHCA times were independently associated with PPRS.

CONCLUSIONS

Prolonged postoperative respiratory support is common after proximal aortic surgery. The use of DHCA was not associated with this complication in the overall cohort, although longer DHCA times were predictive when only the subset of patients undergoing DHCA was analyzed. Knowledge of the risk factors for PPRS after proximal aortic surgery should improve preoperative risk stratification and postoperative management of these patients.

Antegrade versus retrograde cerebral perfusion for hemiarch replacement with deep hypothermic circulatory arrest: does it matter? A propensity-matched analysis

OBJECTIVE

The choice of cerebral perfusion strategy for aortic arch surgery has been debated, and the superiority of antegrade (ACP) or retrograde (RCP) cerebral perfusion has not been shown. We examined the early and late outcomes for ACP versus RCP in proximal (hemi-) arch replacement using deep hypothermic circulatory arrest (DHCA).

METHODS

A retrospective analysis of a prospectively maintained database was performed for all patients undergoing elective and nonelective hemiarch replacement at a single referral institution from June 2005 to February 2013. Total arch cases were excluded to limit the analysis to shorter DHCA times and a more uniform patient population for whom clinical equipoise regarding ACP versus RCP exists. A total of 440 procedures were identified, with 360 (82%) using ACP and 80 (18%) using RCP. The endpoints included 30-day/in-hospital and late outcomes. A propensity score with 1:1 matching of 40 pre- and intraoperative variables was used to adjust for differences between the 2 groups.

RESULTS

All 80 RCP patients were propensity matched to a cohort of 80 similar ACP patients. The pre- and intraoperative characteristics were not significantly different between the 2 groups after matching. No differences were found in 30-day/in-hospital mortality or morbidity outcomes. The only significant difference between the 2 groups was a shorter mean operative time in the RCP cohort (P = .01). No significant differences were noted in late survival (P = .90).

CONCLUSIONS

In proximal arch operations using DHCA, equivalent early and late outcomes can be achieved with RCP and ACP, although the mean operative time is significantly less with RCP, likely owing to avoidance of axillary cannulation. Questions remain regarding comparative outcomes with straight DHCA and lesser degrees of hypothermia.

Stented elephant trunk technique for retrograde type A aortic dissection after endovascular stent graft repair

BACKGROUND

Retrograde type A aortic dissection is a rare but deadly complication after thoracic endovascular aortic repair of type B aortic dissection. Total arch replacement combined with a modified stented elephant trunk technique (SET), was performed for these complicated dissections. We reviewed our results of the procedure for this serious complication, aiming to evaluate the feasibility of the technique.

METHODS

Between April 2005 and September 2012, 24 patients with retrograde type A aortic dissection after thoracic endovascular aortic repair underwent the SET procedure in our center. The mean age at operation was 44.1±8.8 years old. Postoperative mortality and morbidity were analyzed to evaluate the immediate and mid-term results.

RESULTS

Death at 30 days was 4.2% (1 of 24 patients). No patient suffered paraplegia or stroke after operation. Follow-up was completed with 23 survivors. The mean follow-up period was 32.2±13.1 months (range, 12 to 49 months). No late deaths occurred during follow-up. One patient underwent reoperation for replacement of the thoracoabdominal aorta and enjoyed an uneventful survival.

CONCLUSIONS

The stented elephant trunk technique could be an alternative for treatment of retrograde type A aortic dissection with acceptable surgical risks and satisfactory results.

A meta-analysis of deep hypothermic circulatory arrest versus moderate hypothermic circulatory arrest with selective antegrade cerebral perfusion

INTRODUCTION

A recent concern of deep hypothermic circulatory arrest (DHCA) in aortic arch surgery has been its potential association with increased risk of coagulopathy, elevated inflammatory response and end-organ dysfunction. Recently, moderate hypothermic circulatory arrest (MHCA) with selective antegrade circulatory arrest (SACP) seeks to negate potential hypothermia-related morbidities, while maintaining adequate neuroprotection. The present meta-analysis aims to compare postoperative outcomes in arch surgery using DHCA or MHCA+SACP as neuroprotective strategies.

METHODS

Electronic searches were performed using six databases from their inception to January 2013. Two reviewers independently identified all relevant studies comparing DHCA with MHCA+SACP, as defined by a recent hypothermia temperature consensus. Data were extracted and meta-analyzed according to pre-defined clinical endpoints.

RESULTS

Nine comparative studies were identified for inclusion in the present meta-analysis. Stroke rates were significantly lower in patients undergoing MHCA+SACP (P=0.0007, I(2)=0%), while comparable results were observed with temporary neurological deficit, mortality, renal failure or bleeding. Infrequent and inconsistent reporting of systemic outcomes precluded analysis of other systemic outcomes.

CONCLUSIONS

The present meta-analysis indicated the superiority of MHCA+SACP in terms of stroke risk.