Retrograde Cerebral Perfusion Is Effective for Prolonged Circulatory Arrest in Arch Aneurysm Repair

Open, endovascular or hybrid repair of aortic arch disease: narrative review of diverse strategies with diverse options

OBJECTIVES

The management of aortic arch disease is complex. Open surgical management continues to evolve, and the introduction of endovascular repair is revolutionizing aortic arch surgery. Although these innovative techniques have generated the opportunity for better outcomes in select patients, they have also introduced confusion and uncertainty regarding best practices.

METHODS

In New York, we developed a collaborative group, the New York Aortic Consortium, as a means of cross-linking knowledge and working together to better understand and treat aortic disease. In our meeting in May 2023, regional aortic experts and invited international experts discussed the contemporary management of aortic arch disease, differences in interpretation of the available literature and the integration of endovascular technology into disease management. We summarized the current state of aortic arch surgery in this review article.

RESULTS

Approaches to aortic arch repair have evolved substantially, whether it be methods to reduce cerebral ischaemia, improve haemostasis, simplify future operations or expand options for high-risk patients with endovascular approaches. However, the transverse aortic arch remains challenging to repair. Among our collaborative group of cardiac/aortic surgeons, we discovered a wide disparity in our practice patterns and our management strategies of patients with aortic arch disease.

CONCLUSIONS

It is important to build unique institutional expertise in the context of complex and evolving management of aortic arch disease with open surgery, endovascular repair and hybrid approaches, tailored to the risk profiles and anatomical specifics of individual patients.

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.

Reoperative total arch replacement after previous cardiovascular surgery: Outcomes in 426 consecutive patients

OBJECTIVE

Total aortic arch replacement (TAR) after previous cardiovascular surgery is technically challenging and is becoming more frequent as outcomes for primary arch repair have improved. primary. We analyzed outcomes of reoperative compared with first-time TAR.

METHODS

The institutional aortic database was queried to identify consecutive patients undergoing TAR between 1997 and 2022. In total, 426 patients underwent TAR, of whom 150 (35%) had previous cardiovascular surgery (reop TAR) and 276 (65%) underwent their first cardiovascular operation.

RESULTS

The reop TAR group was younger (61 ± 13 vs 71 ± 11, P < .001) with more comorbidities such as ischemic heart disease (12% vs 4.3%, P = .006), previous stroke (36% vs 14.5%, P < .001), and renal impairment (24% vs 12.7%, P = .004). Reop TAR had longer cardiac ischemic times (119.3 ± 45.5 minutes vs 98 ± 31.9 minutes, P < .001), a greater operative mortality (3.3% vs 0.4%, P = .040), and incurred a 4-fold increased risk of major adverse event (95% confidence interval [CI], 1.41-11.49, P = .009). Ten-year survival was also lower in the reop TAR cohort (76% vs 82.2%; hazard ratio, 1.79; 95% CI, 1.12-2.86, P = .015) and there was greater need for late reinterventions, mainly on the downstream aorta (hazard ratio, 1.29; 95% CI, 1.03-1.62, P = .024).

CONCLUSIONS

Reop TAR is a technically challenging operation and is associated with increased operative mortality and adverse events. Gratifying results can be obtained with meticulous surgical planning and focused attention on end-organ protection. Late reinterventions occur in a significantly greater percentage of patients undergoing reop TAR, and future studies should focus attention on identifying those at-risk groups who may benefit from a more aggressive index procedure.

Short- and long-term results of total arch replacement: Comparison between island and debranching techniques

OBJECTIVE

The 2 most acceptable techniques for reimplantation of the supra-aortic vessels in total arch replacement include the branched graft technique (debranching) or en bloc technique (island). We aim to review our experience with total arch replacement and report short- and long-term outcomes from a high-volume center dedicated to surgery for the thoracic aorta.

METHODS

The aortic surgery database was queried to identify all consecutive patients undergoing total arch replacement between 1997 and 2022. Of the 426 patients who underwent total arch replacement, 303 (71%) received the island technique and 123 (29%) received the debranching approach. Operative and long-term outcomes were compared using multivariable models.

RESULTS

The debranching group was younger (64 ± 14 years vs 69 ± 12 years, P = .001), had undergone more previous cardiac operations (54.5% vs 27.4%, P < .001), and had more connective tissue disorder (20.3% vs 4.6%, P < .001). The debranching approach was associated with longer total circulatory arrest time (47 ± 15 minutes vs 37 ± 10 minutes, P < .001) and cardiac ischemic time (116 ± 41 minutes vs 100 ± 37 minutes, P < .001). More patients in the debranching group received blood products intraoperatively or postoperatively (56.1% vs 42.9%, P = .018). All other early outcomes did not differ between groups. Overall operative mortality was 1.4% (2.4% vs 1%, P = .486); the incidence of major postoperative complications was 6.3% (5.7% vs 6.6%, P = .897). Ten-year survival was 80% (78% vs 80.9%, log-rank P = .356). Multivariable Cox regression analysis demonstrated that neither surgical approach was associated with survival advantage (hazard ratio, 1.18; 0.73-1.89; P = .495).

CONCLUSIONS

Debranching requires a longer operative time, with similar early and long-term outcomes. Preoperative comorbidity, not surgical technique, predicts major adverse events and long-term survival.

Challenging Paradigm Limits of Retrograde Cerebral Perfusion During Lower Body Circulatory Arrest

INTRODUCTION

Retrograde cerebral perfusion (RCP) is a safe and effective technique to augment cerebral protection during lower body circulatory arrest in patients undergoing elective hemiarch replacement. However, recommendations guiding optimal temperature, flow rate, and perfusion pressure are outdated and potentially overly limiting. We report our experience using RCP for elective hemiarch replacement with parameters that challenge the currently accepted paradigm.

METHODS

This was a single-center, retrospective analysis of 319 adult patients who underwent elective hemiarch replacement between February 2010 and 2021 using hypothermic lower body circulatory arrest with RCP alone, RCP followed by antegrade cerebral perfusion (ACP), or ACP alone. Flow rates were adjusted to maintain cerebral perfusion pressure between 30 and 50 mm Hg for RCP and between 40 and 60 mm Hg for ACP.

RESULTS

RCP was used in 22.6% (n = 72) of cases, whereas ACP alone was performed in 77.4% (n = 247) of cases. Baseline patient characteristics were similar between groups. Patients undergoing RCP demonstrated shorter cross-clamp time (97.0 min versus 100.0 min, P = 0.034) and shorter lower body circulatory arrest time (7.0 min versus 10.0 min, P < 0.0001) compared with ACP alone. Nadir bladder temperature was equivalent between groups (27.3°C versus 27.5°C, P = 0.752). There were no significant differences in postoperative complications, neurologic outcomes, or mortality.

CONCLUSIONS

Moderate hypothermic lower body circulatory arrest combined with RCP at target perfusion pressures of 30-50 mm Hg in patients undergoing elective hemiarch replacement results in equivalent neurologic outcomes and overall morbidity to cases using ACP alone. These results challenge the currently accepted paradigm for RCP, which typically uses deep hypothermia while keeping perfusion pressures below 25 mm Hg.

Prolonged Periods of Antegrade Cerebral Perfusion Are Safe During Elective Arch Surgery

BACKGROUND

Cerebral circulatory arrest times >40 minutes during aortic surgery have previously been shown to be associated with increased morbidity and mortality. The purpose of this study was to redefine what would constitute a safe period of circulatory arrest for patients who underwent elective proximal aortic operations requiring antegrade cerebral perfusion (ACP).

METHODS

The ARCH International aortic database was queried, and 2008 patients undergoing elective arch operations with circulatory arrest using ACP were identified. Circulatory arrest time was categorized a priori in 10-minute intervals. To further determine the impact of this variable on outcomes, hierarchical multivariable regression analysis was performed.

RESULTS

Unadjusted mortality increased with increasing circulatory arrest time from 4.8% (<40 minutes) to 13.5% (>90 minutes; P < .001), but risk of stroke was not impacted (P = .4). When treated as a continuous variable, mortality increased significantly with increasing circulatory arrest time, whereas the risk of permanent stroke did not. Using <40 minutes as the reference, multivariable analysis showed no statistical increase in mortality for ranges up to 80 minutes of circulatory arrest. The risk of permanent stroke was not significantly higher for any time interval >40 minutes up to 90 minutes.

CONCLUSIONS

In this series of patients who underwent elective proximal aortic surgery using ACP, periods of circulatory arrest up to at least 80 minutes were not associated with significant increases in mortality or permanent stroke. Modern perfusion strategies have allowed for increased safety during elective arch cases requiring prolonged periods of circulatory arrest.

Evaluation of Different Cannulation Strategies for Aortic Arch Surgery Using a Cardiovascular Numerical Simulator

Aortic disease has a significant impact on quality of life. The involvement of the aortic arch requires the preservation of blood supply to the brain during surgery. Deep hypothermic circulatory arrest is an established technique for this purpose, although neurological injury remains high. Additional techniques have been used to reduce risk, although controversy still remains. A three-way cannulation approach, including both carotid arteries and the femoral artery or the ascending aorta, has been used successfully for aortic arch replacement and redo procedures. We developed circuits of the circulation to simulate blood flow during this type of cannulation set up. The CARDIOSIM© cardiovascular simulation platform was used to analyse the effect on haemodynamic and energetic parameters and the benefit derived in terms of organ perfusion pressure and flow. Our simulation approach based on lumped-parameter modelling, pressure-volume analysis and modified time-varying elastance provides a theoretical background to a three-way cannulation strategy for aortic arch surgery with correlation to the observed clinical practice.

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.

Optimal brain protection in aortic arch surgery

There is considerable debate with regard to the optimal cerebral protection strategy during aortic arch surgery. There are three contemporary techniques in use which include straight deep hypothermic circulatory arrest (DHCA), DHCA with retrograde cerebral perfusion (DHCA + RCP), and moderate hypothermic circulatory arrest with antegrade cerebral perfusion (MHCA + ACP). Appropriate application of these methods ensures appropriate cerebral, myocardial, and visceral protection. Each of these techniques has benefits and drawbacks and ensuring coordinated circulation management strategy is critical to safe performance of aortic arch surgery. In this report, we will review various cannulation strategies, review logistics of hypothermia, and review the relevant literature to outline the strengths and weaknesses of these various cerebral protection strategies.

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.

Alternative Approach for Cerebral Protection during Complex Aortic Arch and Redo Surgery

Total arch replacement remains a very demanding surgical procedure. It can be associated with reasonable long-term outcomes but carries serious perioperative complications. Aortic arch surgery has progressed in recent years to a wider adoption of reproducible and reliable techniques. Conventional open, surgical aortic arch replacement is currently offered to the majority of patients, although hybrid and wholly endovascular techniques are gaining popularity. With regards to open arch replacement, the nuances of surgical technique, the mode of cannulation and the optimal cerebral protection protocols remain a matter of debate. We propose an alternative cannulation approach facilitated by the cooperation between cardiac and vascular surgeons. A three-way arterial cannulation including both carotid arteries and the femoral artery (or ascending aorta) is the key feature of this approach. A case series of complex patients is presented to show both the feasibility and relative safety of a standardised new approach with a 100% technical success rate and a 16% 30-day mortality. The three-way cannulation approach may have a role to play for complex and extensive procedures requiring prolonged cerebral protection. We believe that a shared skill set from cardiac and vascular specialists is essential for the safe management and successful outcomes using this adaptive technique.

Estimation Model for Hypothermic Circulatory Arrest Time to Predict Risk in Total Arch Replacement

BACKGROUND

We created an estimation model for hypothermic circulatory arrest time and analyzed the risk factors for major adverse outcomes in total arch replacement.

METHODS

This study involved 272 patients who underwent total arch replacement. The estimation model for hypothermic circulatory arrest time was established using multiple linear regression analysis, and the predicted hypothermic circulatory arrest time from this model was analyzed to detect risk factors.

RESULTS

Atrial fibrillation, rupture, malperfusion, saccular aneurysm, cardiopulmonary bypass time, and hypothermic circulatory arrest time were identified as independent risk factors associated with major adverse outcomes. The estimation model for hypothermic circulatory arrest time was established as follows: hypothermic circulatory arrest time = 99.3 - 0.19 × age + 0.65 × body mass index + 6.19 × previous cardiac operation + 11.7 × acute dissection + 8.9 × rupture + 0.19 × aortic angulation + 0.15 × length to the distal anastomosis site - 6.17 × total arch replacement surgeon case volume - 3.06 × surgery year. The predicted hypothermic circulatory arrest time calculated by this estimation model was evaluated using multivariate logistic analysis, which identified atrial fibrillation, rupture, malperfusion, saccular aneurysm, and predicted hypothermic circulatory arrest time as risk factors.

CONCLUSIONS

As with the actual hypothermic circulatory arrest time, the predicted hypothermic circulatory arrest time using our model detected significant factors associated with major adverse outcomes. These results indicated that this prediction model for hypothermic circulatory arrest time may be effective.

A tailored strategy for repair of acute type A aortic dissection

OBJECTIVE

Innumerable surgical techniques are currently deployed for repairing acute type A aortic dissection (ATAAD). We analyzed our results using a conservative approach of root-sparing and hemiarch techniques in higher-risk patients and root and total arch replacement for lower-risk patients.

METHODS

We queried our aortic database for consecutive patients who underwent ATAAD repair. Patients who underwent conservative repair (group 1) were compared with those who underwent extensive repair (group 2) using univariable and multivariable analysis.

RESULTS

From 1997 to 2019, 343 patients underwent ATAAD repair. Two hundred forty had conservative repair (root-sparing, hemiarch) whereas 103 had extensive repair (root replacement and/or total arch). Group 1 was older with more comorbidities such as hypertension, previous myocardial infarction, and renal dysfunction. Group 2 had more connective tissue disease (2.1% vs 12.6%; P < .01), aortic insufficiency, and longer intraoperative times. The incidence of individual postoperative complications was similar regardless of approach. A composite of major adverse events (operative mortality, myocardial infarction, stroke, dialysis, or tracheostomy) was higher in the conservative group (15.1% vs 5.9%; P = .03). Operative mortality was 5.6% and not different between groups. Ten-year survival was similar with either surgical approach. Ten-year cumulative risk of reintervention was greater in group 2 (5.6% vs 21% at 10 years; P < .01). In multivariable analysis, ejection fraction and diabetes were predictors of major adverse events but not extensive approach. Extensive approach was a predictor of late reoperation (odds ratio, 3.03 [95% confidence interval, 1.29-7.2]; P = .01).

CONCLUSIONS

A tailored conservative approach to ATAAD leads to favorable operative outcomes without compromising durability.

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.

Management of malperfusion: New York approach and outcomes

BACKGROUND AND AIM

Aortic branch malperfusion complicates up to one-third of acute type A aortic dissection (ATAAD), and it is a strong predictor of poor outcomes. We analyzed our results for the surgical management of this high-risk cohort.

METHODS

We queried our aortic database for consecutive patients undergoing ATAAD repair. Those presenting with malperfusion were compared with those without. Outcomes were compared using univariate and multivariate analysis.

RESULTS

From 1997 to 2019, a total of 336 patients underwent ATAAD repair. A total of 97 ATAAD patients presented with malperfusion. Malperfusion patients were more likely to be male (54.8% vs. 75.3%; p = .001), have had a prior myocardial infarction (11.9% vs. 26.8%; p = .001), to present with preoperative renal dysfunction (22.2% vs. 54.6%; p < .001), and to present with shock (12.6% vs. 28.9%; p = .001). The malperfusion group more often underwent coronary artery bypass grafting (5.4% vs. 24.7%; p < .001), and required additional noncardiac procedures 10.3% of the time. Operative mortality (0.8% vs. 15.5%; p < .001) and major adverse events (MAEs) (7.6% vs. 20.6%; p = .001) were both greater for the malperfusion patients. Ejection fraction, diabetes, and malperfusion were predictors of MAEs. Cerebral, coronary, mesenteric, and multiple vascular bed malperfusion were predictors of MAEs, while extremity, renal, and spinal were not.

CONCLUSION

Improving outcomes for this high-risk cohort requires rapid diagnosis and reversal of ischemia while minimizing the risk of aortic rupture, irrespective of the strategic approach.

Goal-directed cerebral perfusion in aortic arch surgery: scientific leap or hype?

Although significant advancements in cerebral protection strategies in aortic surgery have been achieved in recent years, controversy remains on what constitutes the optimal strategy. Deep hypothermic circulatory arrest alone is a viable approach in many instances, but the need for a prolonged duration of circulatory arrest and increasing case complexity have led to the utilization of adjunctive cerebral perfusion strategies. In this review, we discuss the efficacy of deep hypothermic circulatory arrest and its limitations, the role of retrograde cerebral perfusion and unilateral and bilateral antegrade cerebral perfusion, and the trend towards goal-directed perfusion strategies, all emphasizing the pressing need for randomized clinical trials to better define the optimal strategy.

Optimal Cerebral Protection Strategies in Aortic Surgery

Cerebral protection strategies in aortic surgery have undergone significant evolution over the years, but its tenets remain rooted in maintenance of hypothermia and cerebral perfusion to limit adverse neurologic outcomes. While deep hypothermic circulatory arrest alone remains a viable approach in many instances, the need for prolonged duration of circulatory arrest and increasing case complexity have driven the utilization of adjunctive cerebral perfusion strategies. In this review, we present the most recent studies published on this topic over the last few years investigating the efficacy of deep hypothermic circulatory arrest, retrograde cerebral perfusion, and unilateral and bilateral antegrade cerebral perfusion, as well as the emerging trend toward mild and moderate HCA temperatures. We highlight the ongoing controversies in the field that underscore the need for large-scale randomized trials using well-defined neurologic endpoints to optimize evidence-based practice in cerebral protection.

Simple retrograde cerebral perfusion is as good as complex antegrade cerebral perfusion for hemiarch replacement

Cerebral complication is a major concern after aortic arch surgery, which may lead to death. Thus, cerebral protection strategy plays the key role to obtain respectable results in aortic arch repair. Deep hypothermic circulatory arrest was introduced in 1970s to decrease the ischemic insults to the brain. However, safe duration of circulatory arrest time was limited to 30 minutes. The 1990s was the decade of evolution for cerebral protection, in which two adjuncts for deep hypothermic circulatory arrest were introduced: retrograde and antegrade cerebral perfusion (ACP) techniques. These two cerebral perfusion techniques significantly decreased incidence of postoperative neurological dysfunction and mortality after aortic arch surgery. Although there are no large prospective studies that demonstrate which perfusion technique provide better outcomes, multiple retrospective studies implicate that ACP may decrease cerebral complications compared to retrograde cerebral perfusion (RCP) when a long circulatory arrest time is required during aortic arch reconstructions. To date, many surgeons favor ACP over RCP during a complex aortic arch repair, such as total arch replacement and hybrid arch replacement. However, the question is whether the use of ACP is necessary during a short, limited circulatory arrest time, such as hemiarch replacement? There is a paucity of data that proves the advantages of a complex ACP over a simple RCP for a short circulatory arrest time. RCP with deep hypothermic circulatory arrest is the simple, efficient cerebral protection technique with minimal interference to the surgical field-and it potentially allows to flush atheromatous debris out from the arch vessels. Thus, it is the preferred adjunct to deep hypothermic circulatory arrest during hemiarch replacement in our institution.