Establishment of cerebral perfusion in a rat model with extracorporeal life support

Background: Extracorporeal life support echniques as an Adjunct to Advanced Cardiac Life Support is usually suitable for complex heart surgery such as cardiopulmonary bypass (CPB). Cerebral perfusion is a clinically feasible neuroprotective strategy; however, the lack of a reliable small animal model.Methods: Based on the rat model of ECLS we evaluate the effects of ECLS-CP using HE staining, Nissl staining, TUNEL staining and ELISA.Result: We found that ECLS combined with the cerebral perfusion model did not cause brain injury and immune inflammation. There was no difference between the two by a left carotid artery or right carotid artery CP.Conclusion: These experimental results can provide the experimental basis for selecting blood vessels for ECLS patients and clinical CP to offers a trustworthy animal model for future exploration of applying brain perfusion strategies during ECLS-CP.

Optimization of Hypothermic Protocols for Neurocognitive Preservation in Aortic Arch Surgery: A Literature Review

Shifts from deep to moderate hypothermic circulatory arrest (HCA) in aortic arch surgery necessitate an examination of their differential impacts on neurocognitive functions, especially structured verbal memory, given its significance for patient recovery and quality of life. This study evaluates and synthesizes evidence on the effects of deep (≤20.0 °C), low-moderate (20.1-24.0 °C), and high-moderate (24.1-28.0 °C) hypothermic temperatures on structured verbal memory preservation and overall cognitive health in patients undergoing aortic arch surgery. We evaluated the latest literature from major medical databases such as PubMed and Scopus, focusing on research from 2020 to 2024, to gather comprehensive insights into the current landscape of temperature management during HCA. This comparative analysis highlights the viability of moderate hypothermia (20.1-28.0 °C), supported by recent trials and observational studies, as a method to achieve comparable neuroprotection with fewer complications than traditional deep hypothermia. Notably, low-moderate and high-moderate temperatures have been shown to support substantial survival rates, with impacts on structured verbal memory preservation that necessitate careful selection based on individual surgical risks and patient profiles. The findings advocate for a nuanced approach to selecting hypothermic protocols in aortic arch surgeries, emphasizing the importance of tailoring temperature management to optimize neurocognitive outcomes and patient recovery. This study fills a critical gap in the literature by providing evidence-based recommendations for temperature ranges during HCA, calling for ongoing updates to clinical guidelines and further research to refine these recommendations. The implications of temperature on survival rates, complications, and success rates underpin the necessity for evolving cardiopulmonary bypass techniques and cerebral perfusion strategies to enhance patient outcomes in complex cardiovascular procedures.

The Call for the "Interventional/Hybrid" Aortic Surgeon: Open, Endovascular, and Hybrid Therapies of the Aortic Arch

Aortic arch pathology is relatively rare but potentially highly fatal and associated with considerable comorbidity. Operative mortality and complication rates have improved over time but remain high. In response, aortic arch surgery is one of the most rapidly evolving areas of cardiac surgery in terms of surgical volume and improved outcomes. Moreover, there has been a surge in novel devices and techniques, many of which have been developed by or codeveloped with vascular surgeons and interventional radiologists. Nevertheless, the extent of arch surgery, the choice of nadir temperature, cannulation, and perfusion strategies, and the use of open, endovascular, or hybrid options vary according to country, centre, and surgeon. In this review article, we provide a technical overview of the surgical, total endovascular, and hybrid repair options for aortic arch pathology through historical developments and contemporary results. We highlight key information for surgeons, cardiologists, and trainees to understand the management of patients with aortic arch pathology. We conclude by discussing training paradigms, the role of aortic teams, and gaps in knowledge, arguing for the need for wire skills for the future "interventional aortic surgeon" and increased research into techniques and novel devices to continue improving outcomes for aortic arch surgery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

REGISTRATION

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

Cannula Placement for Cerebral Protection Without Circulatory Arrest in Patients Undergoing Hemiarch Aortic Aneurysm Repair

BACKGROUND

Aortic aneurysms involving the proximal aortic arch, which require hemiarch-type repair, typically require circulatory arrest with antegrade cerebral perfusion. Left carotid antegrade cerebral perfusion (LCP) via distal arch cannulation without circulatory arrest was used in this study's patient population. The goal was to assess the operative efficiency and clinical outcomes of using a distal arch cannulation technique that would not require any hypothermic circulatory arrest (HCA) time compared with more traditional brachiocephalic artery cannulation with right-sided unilateral antegrade cerebral perfusion (RCP) and HCA.

METHODS

A single-center retrospective review of patients with replacement of the distal ascending aorta involving the proximal arch was performed. Patients with an intramural hematoma or dissection were excluded. Between January 2015 and December 2019, 68 adult patients had undergone a hemiarch repair because of aneurysmal disease. Analysis of baseline demographics, operative data, and clinical outcomes was performed.

RESULTS

Comparing the 68 patients: 21 patients were treated with RCP (via brachiocephalic artery graft with HCA), and 47 patients were treated with LCP (via distal aortic arch cannulation with cross-clamp between the brachiocephalic and left common carotid arteries without HCA). Baseline characteristics and outcomes were evaluated for both groups. The LCP group was younger (LCP median [IQR] age, 60 [53-65] years vs RCP median [IQR] age, 67 [59-71] years]. Sex, race, body mass index, comorbidities, and ejection fraction were similar between the groups. Cardiopulmonary bypass time (LCP, 123 minutes vs RCP, 149 minutes) and unilateral cerebral perfusion time (LCP, 17 minutes vs RCP, 22 minutes) were longer in the RCP group. Bleeding, prolonged ventilatory support, kidney failure, and length of stay were similar. In-hospital mortality was 2% in the LCP group vs 0% in the RCP group. Stroke occurred in 2 patients (4.2%) in the LCP group and in 0% of the RCP group. Mortality at 6 months in the LCP and RCP groups was 3% and 10%, respectively.

CONCLUSION

Distal arch cannulation with LCP without HCA is a reasonable and safe alternative strategy for patients requiring hemiarch replacement for aneurysmal disease. This technique may provide additional benefits by avoiding circulatory arrest in these complex cases.

Total Arch Thoracic Endovascular Aortic Repair Using Double Fenestrated Physician-Modified Stent-Grafts: 100 Patients

OBJECTIVE

The aim was to evaluate early and medium-term outcomes of double fenestrated physician-modified endovascular grafts for total endovascular aortic arch repair.

METHODS

This single-center retrospective analysis of prospectively-collected data included 100 patients, from January 2017 to December 2021, undergoing thoracic endovascular aortic repair (TEVAR) for zone 0. The fenestrations were a proximal larger fenestration that incorporated the brach2iocephalic trunk and left common carotid artery and a distal smaller fenestration for the left subclavian artery (LSA). Only the LSA fenestration was stented.

RESULTS

The median duration for stent-graft modification was 23±6 minutes. Of the 100 patients, 70 were men. The mean patient age was 70±10.5 years. Indications for treatment included degenerative aortic arch aneurysm (n=32), dissecting aortic arch aneurysm after type A dissections (n=23) and (n=19) after type B dissections, acute complicated type B dissection (n=16), and other pathologies (n=10). Technical success rate was 97%. The 30 day mortality was 2% (n=2). Four patients (4%) had minor stroke with full recovery. One patient (1%) had a type IA endoleak, 1 patient (1%) had a type IB endoleak, and 2 patients (2%) have a type II endoleak from the LSA. Eight patients (8%) required reintervention: 1 type IA endoleak, 1 type IB endoleak, 1 retrograde type A dissection, and 5 because of access-related complications. During a mean follow-up of 24±7.2 months, there were no aortic rupture, paraplegia, and all supra-aortic trunks were patent.

CONCLUSIONS

Double homemade fenestrated TEVAR is both feasible and effective for total endovascular aortic arch repair avoiding the need for anatomical and extra-anatomical surgical revascularization. The long-term durability will need to be assessed in studies with long-term follow-up.

CLINICAL IMPACT

Double homemade fenestrated TEVAR is effective for total endovascular aortic arch repair avoiding the need for anatomical and extra-anatomical surgical revascularization. The standout feature of this double fenestrated device is its simple handling during operation with the proximal fenestrations being directed to the orifices of the BT and LCCA automatically when the LSA fenestration is catheterized and secured by covered stent placement. The deployment algorithm actively steers the operator away from superfluous manipulations of the device within the arch and avoids guidewire manipulation in carotid arteries. The long-term durability will need to be assessed in studies with long-term follow-up.

Can Open Distal Repair Be Safely Used in All Patients with Type A Acute Aortic Dissection?

PURPOSE

The distal suture line during aortic dissection repair can be performed by a closed technique or by an open technique. This study presents a retrospective comparison of both methods regarding their postoperative outcomes.

PATIENTS AND METHODS

120 patients who underwent surgery for acute aortic dissection type A were divided into two groups. In group A (n = 81), open distal anastomosis was performed under hypothermic circulatory arrest and selective cerebral perfusion. In group B (n = 39), distal anastomosis was performed with the aorta cross-clamped under mildly hypothermic cardiopulmonary bypass. Primary outcomes were operative mortality, neurologic morbidity, and long-term survival.

RESULTS

Hospital mortality (17.3% for the open group vs. 12.8% for the closed group, p = 0.53), permanent neurologic dysfunction (8.7% vs. 8.3%, p = 1.0), and temporary neurologic dysfunction (31.9% vs. 22.2%, p = 0.298) were not significantly different between groups. No significant difference in actuarial 5- and 10-year survival was observed (88% vs. 86% and 53 vs. 73%, respectively, p = 0.396). After propensity-score adjustment, the technique of distal aortic repair was not found to be a predictor of the primary outcomes.

CONCLUSION

We conclude that the open repair can be used in most if not all cases of surgical repair of type A acute aortic dissection.

Perfusion management of arch-clamping technique in total arch replacement with frozen elephant trunk

A technique called arch-clamping was used at our institute to ensure perfusion of the lower body and brain during total arch replacement with frozen elephant trunk (TAR and FET). The aortic arch clamp is inserted between the left common carotid artery and the left subclavian artery after inserting the stented elephant trunk into the true lumen of the descending aorta during the procedure, and then clamps the aorta and graft together as the distal anastomotic edge of the aorta. After the arch clamp was in place, lower body perfusion was resumed through the femoral artery was resumed and time to circulatory arrest was reduced to approximately 4 min. Cardiopulmonary bypass (CPB) flow was gradually restored to full rate. Thereafter, the left carotid artery anastomosis was completed and rewarming began. Finally, during the rewarming period, other branches of the aortic arch and ascending aorta were reconstructed. In this paper, we describe the perfusion management strategy, discuss intraoperative monitoring parameters, and examine the feasibility of the technique from a perfusion perspective.

Cerebral protection strategies for type A aortic dissection repair

Importance

Techniques to preserve neurological function during type A aortic dissection repairs have been broadly discussed in the literature and heavily debated. Despite the effectiveness of various approaches, a consensus lacks on how to maintain optimal cerebral temperature during surgery. This review examines the three predominant cerebral protection strategies in aortic arch reconstructions: straight deep hypothermic circulatory arrest (sDHCA), retrograde cerebral perfusion (RCP), and antegrade cerebral perfusion (ACP).

Observations

The signature characteristics of sDHCA, RCP, and ACP are similar-hypothermia, with or without cerebral perfusion. Employing cerebral perfusion techniques may prolong operative times, while ACP permits operation at higher body temperatures, albeit with restricted operative durations.

Conclusion

For type A dissection arch reconstructions, sDHCA, RCP, and ACP can be successfully implemented. Factors such as operative times and individual patient conditions should be considered when choosing a cerebral protection strategy.

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

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

Retrograde Cerebral Perfusion May Decrease Stroke Risk During Elective Aortic Arch Surgery

OBJECTIVE

Controversy remains regarding the optimal neuroprotection strategy for elective hemiarch replacement (HEMI). This study sought to compare outcomes in patients who underwent HEMI utilizing the 2 most common contemporary methods of cerebral protection.

METHODS

The ARCH international aortic database was queried, and 782 patients undergoing elective HEMI with circulatory arrest from 2007 to 2012 were identified. There were 418 patients who underwent HEMI using moderate hypothermia (nasopharyngeal temperature 20.1 to 28.0 °C) and antegrade cerebral perfusion (MHCA/ACP). There were 364 patients who underwent HEMI using deep hypothermia (nasopharyngeal temperature 14.1 to 20 °C) and retrograde cerebral perfusion (DHCA/RCP). Adverse outcomes were compared between the groups using both univariable and multivariable analyses.

RESULTS

Patients who underwent MHCA/ACP were older (64 vs 61 years, P = 0.01) and more frequently had peripheral vascular disease than DHCA/RCP patients (28.5% vs 7.1%, P < 0.001). Patients in the DHCA/RCP group had a greater incidence of full aortic root replacement (55.8% vs 26.4%, P < 0.001) and more frequently had a central cannulation strategy (83% vs 55.7%, P < 0.001). Cardiopulmonary bypass (170 vs 157 min, P = 0.002) and aortic cross-clamp (134 vs 92 min, P < 0.001) times were significantly longer in the DHCA/RCP group. On univariable analysis, overall mortality was statistically similar between groups (MHCA/ACP 3.4% vs DHCA/RCP 2.3%, P = 0.47), but permanent neurologic deficits were significantly lower in the DHCA/RCP cohort (MHCA/ACP 3.9% vs DHCA/RCP 1.0%, P = 0.02). Multivariable analysis showed no difference in mortality nor perioperative stroke between perfusion cohorts.

CONCLUSIONS

Both MHCA/ACP and DHCA/RCP are excellent neuroprotective strategies that produce low mortality in patients undergoing elective HEMI. DHCA/RCP may demonstrate theoretically improved neurologic outcomes compared with MHCA/ACP, but this topic warrants further study.

Endovascular Options for the Ascending Aorta and Aortic Arch - A Scoping Review

The gold standard for aneurysmal repair of the ascending aorta and the aortic arch has been open surgery with an established track record of good results in suitable patients. In recent years, with innovations in the endovascular field alternative endovascular solutions for pathologies of the aortic arch and ascending aorta became available. At first reserved only for highly selected patients unfit for open surgery, endovascular aortic arch repair is now being offered to patients with suitable anatomy in high volume referral centers after discussion in an interdisciplinary team. The present scoping review aims at providing an overview on indications, available devices, technical aspects and feasibility studies of endovascular arch repair both in elective and emergent situations, including also experiences and considerations from our center.

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.

Preliminary results from an Italian National Registry on the outcomes of the Najuta fenestrated aortic arch endograft

BACKGROUND

Arch pathology represents one of the last frontiers in aortic aneurysm endovascular management. Several companies recently developed dedicated branched and fenestrated endografts specifically designed for the aortic arch, aiming to overcome some of the issues associated with standard thoracic endograft and supra-aortic vessels extra-anatomic debranching. This study aimed to evaluate early outcomes obtained with a custom-made fenestrated endograft approved for thoracic aortic aneurysms exclusion.

METHODS

All consecutive patients treated with the Najuta endograft (Kawasumi Laboratories, Inc, Tokyo, Japan) in Italy were enrolled prospectively and included in the study population. Anatomic characteristics and perioperative data were analyzed retrospectively. Study end points were technical success, 30-day clinical success, overall survival, supra-aortic vessel patency, endoleak, and need for reintervention or surgical conversion.

RESULTS

Between 2018 and 2022, 76 patients received a Najuta endograft in Italy and were enrolled in the study. The median patient age was 72 years (interquartile range, 69-76 years) and 80.3% were male. Most of the patients received treatment for atherosclerotic aneurysms (80.3%); others were treated for postdissection aneurysms (7.9%), penetrating aortic ulcer (9.2%), or type I endoleak correction after previous thoracic endovascular repair (2.6%). Overall, 161 supra-aortic vessels were preserved through a dedicated fenestration. Technical success was achieved in 74 of 76 procedure (97.4%); both failures were associated with endoleak detection at final angiography (one type I and one type III endoleak). Two distal migrations occurred during the implanting procedure. Clinical success at 30 days was 94.7%. Two early reinterventions were needed within 30 days after index procedure: in one case, an aortic false lumen coils embolization was performed, because distal re-entry caused enlargement of the postdissection thoracic aneurysm. The other procedure consisted of a femoral pseudoaneurysm repair. The median follow-up was 7 months (interquartile range, 3-15 months); no supra-aortic vessel occlusions occurred and no patients needed surgical conversion.

CONCLUSIONS

Early results suggest that, in selected patients with aortic arch pathology needing a proximal landing, an endovascular approach with the Najuta system is safe and effective, especially for those at high surgical risk. A strict follow-up with high-quality computed tomography angiography images and eventual evaluation for long-term complications is needed to confirm these initial experience findings.

Proximal aortic repair in dialysis patients: A national database analysis

OBJECTIVES

Dialysis is a well-established risk factor for morbidity and mortality after cardiovascular procedures. However, little is known regarding the outcomes of proximal aortic surgery in this high-risk cohort.

METHODS

Perioperative (in-hospital or 30-day mortality) and 10-year outcomes were analyzed for all the patients who underwent open proximal aortic repair with the diagnosis of nonruptured thoracic aortic aneurysm (aneurysm, n = 325) or type A aortic dissection (dissection, n = 461) from 1987 to 2015 using the US Renal Data System database.

RESULTS

In patients with aneurysm, perioperative mortality was 12.6%. The 10-year mortality was 81% ± 3%. Age 65 years or more (hazard ratio [HR], 1.35; 95% confidence interval [CI], 1.03 to 1.78; P = .03), chronic obstructive pulmonary disease (HR, 1.68; 95% CI, 1.01-2.82; P = .047), and Black race (HR, 1.46; 95% CI, 1.09-1.97; P = .01) were independently associated with worse 10-year mortality. In patients with dissection, perioperative mortality was 24.3% and 10-year mortality was 87.9% ± 2.2%. Age 65 years or more (HR, 1.49; 95% CI, 1.19-1.86; P < .001), congestive heart failure (HR, 1.39; 95% CI, 1.11-2.57; P = .004), and diabetes mellitus as the cause of dialysis (HR, 1.75; 95% CI, 1.2-2.57; P = .004) were independently associated with worse 10-year mortality. Black race (HR, 0.74; 95% CI, 0.6-0.92; P = .008) was associated with a better outcome.

CONCLUSIONS

We described challenging perioperative and 10-year outcomes for dialysis patients undergoing proximal aortic repair. The present study suggests the need for careful patient selection in the elective repair of proximal aortic aneurysm for dialysis-dependent patients, whereas it affirms the feasibility of emergency surgery for acute type A aortic dissections.

Deep Versus Moderate Hypothermia in Acute Type A Aortic Dissection: A Propensity-Matched Analysis

BACKGROUND

The ideal temperature for hypothermic circulatory arrest (HCA) during acute type A aortic dissection (ATAAD) repair has yet to be determined. We examined the clinical impact of different degrees of hypothermia during dissection repair.

METHODS

Out of 240 cases of ATAAD between June 2014 and December 2019, 228 patients were divided into two groups according to lowest intraoperative temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). From this, 74 pairs of propensity-matched patients were analysed with respect to operative data and short-term clinical outcomes. Independent predictors of a composite outcome of 30-day mortality and stroke were identified.

RESULTS

Mean lowest temperature was 25.5±3.9°C in the MHCA group versus 16.0±2.9°C in DHCA. Overall 30-day mortality of matched cohort was 11.5% (17 deaths), there were no significant different between matched groups. Cardiopulmonary bypass (CPB) times were longer in DHCA (221.0±69.9 vs 190.7±74.5 mins, p=0.01). Antegrade cerebral perfusion (ACP) during HCA predicted a lower composite risk of 30-day mortality and stroke (OR 0.38). Female sex (OR 4.71), lower extremity ischaemia at presentation (OR 3.07), and CPB >235 minutes (OR 2.47), all portended worse postoperative outcomes.

CONCLUSIONS

A surgical strategy of MHCA is at least as safe as DHCA during repair of acute type A aortic dissection. ACP during HCA is associated with reduced 30-day mortality and stroke, whereas female sex, lower extremity ischaemia, and longer CPB times are all predictive of poorer short-term outcomes.

Temperature dependence of dielectric properties of blood at 10 Hz-100 MHz

The temperature dependence of the dielectric properties of blood is important for studying the biological effects of electromagnetic fields, electromagnetic protection, disease diagnosis, and treatment. However, owing to the limitations of measurement methods, there are still some uncertainties regarding the temperature characteristics of the dielectric properties of blood at low and medium frequencies. In this study, we designed a composite impedance measurement box with high heat transfer efficiency that allowed for a four/two-electrode measurement method. Four-electrode measurements were carried out at 10 Hz-1 MHz to overcome the influence of electrode polarization, and two-electrode measurements were carried out at 100 Hz-100 MHz to avoid the influence of distribution parameters, and the data was integrated to achieve dielectric measurements at 10 Hz-100 MHz. At the same time, the temperature of fresh blood from rabbits was controlled at 17-39°C in combination with a temperature-controlled water sink. The results showed that the temperature coefficient for the real part of the resistivity of blood remained constant from 10 Hz to 100 kHz (-2.42%/°C) and then gradually decreased to -0.26%/°C. The temperature coefficient of the imaginary part was positive and bimodal from 6.31 kHz to 100 MHz, with peaks of 5.22%/°C and 4.14%/°C at 126 kHz and 39.8 MHz, respectively. Finally, a third-order function model was developed to describe the dielectric spectra at these temperatures, in which the resistivity parameter in each dispersion zone decreased linearly with temperature and each characteristic frequency increased linearly with temperature. The model could estimate the dielectric properties at any frequency and temperature in this range, and the maximum error was less than 1.39%, thus laying the foundation for subsequent studies.

Rapid cooling is a safe technique in patients undergoing circulatory arrest for aortic repair

Objective

To evaluate our institutional experience with rapid cooling for hypothermic circulatory arrest in proximal aortic repair.

Methods

We retrospectively reviewed data from 2171 patients who underwent proximal aortic surgery requiring hypothermic circulatory arrest between 1991 and 2020. Cooling times were divided into quartiles and clinical outcome event rates were compared across quartiles using contingency table methods. Incremental effect of cooling time was assessed in the context of other perfusion time variables using multiple logistic regression analysis.

Results

Median age was 61 years (interquartile range, 49-70 years) and 34.1% of patients were women. The procedure was emergent in 33.5% of patients, 22.9% had a previous sternotomy. The median circulatory arrest time was 22 minutes, with retrograde cerebral perfusion used in 94% of cases. Median cardiopulmonary bypass time was 149 minutes, with an aortic crossclamp time of 90 minutes. Patients were cooled to deep hypothermia. The first quartile had cooling times ranging from 5 to 13 minutes, second 14 to 18 minutes, third 19-23 minutes, and fourth 24-81 minutes. Overall, 30-day mortality was 9.4%, and was not significantly different across quartiles. There was a statistically significant trend toward lower rates of postoperative encephalopathy, gastrointestinal complications, and respiratory failure with shorter cooling times (P < .001, .006, and < .001, respectively). There was no significant difference in rates of postoperative stroke or dialysis.

Conclusions

Rapid cooling can be performed safely in patients undergoing aortic surgery requiring circulatory arrest without increasing mortality or stroke. There were significantly lower rates of coagulopathy, respiratory failure, and postoperative encephalopathy with shorter cooling times.

Comprehensive review of hybrid aortic arch repair with focus on zone 0 TEVAR and our institutional experience

Even with increasing operator experience and a better understanding of the disease and the operation, intervention for aortic arch pathologies continues to struggle with relatively higher mortality, reintervention, and neurologic complications. The hybrid aortic arch repair was introduced to simplify the procedure and improve the outcome. With recent industry-driven advances, hybrid repairs are not only offered to poor surgical candidates but have become mainstream. This review discusses the evolution of hybrid repair, terminology pertinent to this technique, and results. In addition, we aim to provide a pervasive review of hybrid aortic arch repairs with reference to relevant literature for a detailed understanding. We have also discussed our institutional experience with hybrid repairs.

Does deep hypothermic circulatory arrest with versus without retrograde cerebral perfusion affect the outcomes after proximal aortic arch aneurysm and acute type A aortic dissection repair? Different pathologies and cerebral protection techniques with similar results

Hypothermic circulatory arrest is used for proximal and total aortic arch correction in patients with aortic arch aneurysm and acute or chronic type A aortic dissection. Different cerebral perfusion techniques have been proposed for reducing morbidity and mortality rate. The study of Arnaoutakis et al. showed that deep hypothermic circulatory arrest with or without retrograde cerebral perfusion for proximal aortic aneurysm and acute type A aortic dissection correction had similar results with regard to morbidity and mortality rate. In addition, the short circulatory arrest time contributes for favorable outcomes of these patients. Although antegrade cerebral perfusion with hypothermic circulatory is widely used by many cardiac surgeons, deep hypothermic circulatory arrest with or without retrograde cerebral perfusion remains an alternative and safe method for brain protection in patients undergoing proximal aortic arch aneurysm or acute type A aortic dissection repair.

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.

Safety of retrograde cerebral perfusion under moderate hypothermia for hemiarch replacement

OBJECTIVES

Aortic surgeries performed under moderate hypothermia require antegrade cerebral perfusion. The influence of retrograde cerebral perfusion under moderate hypothermic circulatory arrest remains unknown. To clarify this effect, this study aimed to compare the early outcomes of retrograde versus antegrade cerebral perfusion under moderate hypothermia for hemiarch replacement.

METHODS

Between March 2009 and April 2020, 391 hemiarch replacements under moderate hypothermic circulatory arrest via median sternotomy were performed at our institution. Of these, 70 involved retrograde perfusion and 162 involved antegrade perfusion. Propensity score matching was used to compare 61 pairs of retrograde and antegrade cases.

RESULTS

Retrograde and antegrade strategy under moderate hypothermia resulted in comparable operative mortality (3.3% vs. 1.6%, P > 0.99), permanent neurological deficits (8.5% vs. 6.6%, P > 0.99), and temporary neurological deficits (24.6% vs. 39.3%, P = 0.33). Retrograde surgery was associated with shorter circulatory arrest times (31.4 ± 8.2 min vs. 37.4 ± 12.2 min, P = 0.005) and fewer red blood cell transfusions (4.6 ± 3.9 units vs. 8.2 ± 5.1 units, P < 0.001) than those with antegrade surgery.

CONCLUSIONS

Retrograde cerebral perfusion under moderate hypothermia for hemiarch replacement yields excellent operative outcomes, equivalent to those achieved using an antegrade strategy.

Matched comparison of 3 cerebral perfusion strategies in open zone-0 anastomosis for acute type A aortic dissection

OBJECTIVES

The present study aims to investigate outcomes after the surgical treatment of acute type A aortic dissection in regard to three available selective cerebral perfusion strategies.

METHODS

From 2000 to 2019, patients were selected based on the employment of either retrograde cerebral perfusion (RCP), unilateral antegrade cerebral perfusion (uACP) or bilateral antegrade cerebral perfusion (bACP) during open zone-0 anastomosis. Propensity score TriMatch analysis considering several preoperative and intraoperative variables was used to identify well-balanced triplets. The primary end point of the study was a new cerebral operation-related neurologic deficit.

RESULTS

Operative times (operation time, cardiopulmonary bypass time, reperfusion time) were significantly longer in the RCP group, in which deeper hypothermia was applied (27.5 [24-28], 28 [26-28] and 16 [16-17]°C for uACP, bACP and RCP, respectively, P-value <0.001). The RCP group showed higher red blood cell concentrates and fresh frozen plasma transfusion rates. No significant difference of new cerebral operation-related neurologic deficit was observed between the 3 groups (12.9% vs 12.9% vs 11.3% for RCP, uACP and bACP, P-value = 0.86). In addition, 30-day mortality showed similar distribution independently of the cerebral perfusion strategy adopted (17.7% vs 14.5% vs 17.7% for RCP, uACP and bACP, P-value = 0.86).

CONCLUSIONS

However, based on a small sample size, the comparison showed no relevant differences in terms of neurologic outcome and 30-day mortality, confirming RCP, uACP and bACP as safe and reproducible selective cerebral perfusion strategies in surgery for acute type A aortic dissection.

Antegrade endograft deployment with supra-aortic debranching to treat arch and descending thoracic aortic lesions. A single-center experience

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) is a widely used procedure that has drastically changed the management of thoracic aortic diseases. We assess the effectiveness of supra-aortic debranching during antegrade TEVAR procedures with a retrospective analysis of our clinical experience METHODS: Between December 2005 and April 2017, 55 patients underwent 64 TEVAR procedures. Among them, there were 8 male patients, mean age 72, who underwent hybrid antegrade stent-graft deployment. Particularly, for degenerative aneurysms of the aortic arch 3 patients, for aneurysm of descending thoracic aorta 3, for post-traumatic pseudoaneurysm 1 and for penetrating aortic ulcer 1 which had resulted in an aortoesophageal fistula. Proximal landing zones were Z0:1, Z1:3 and Z2:4. Type I hybrid aortic arch repair was performed in 1 case, carotid-carotid bypass in 2, carotid-subclavian in 5 and aorto-carotid in 1.

RESULTS

The 30-day postoperative mortality was 12,5%. One patient suffered a temporary right hemiplegia which resolved after left aorto-carotid bypass. No endoleaks were observed postoperatively and in follow-up period. In the long term and a mean follow-up of 4.9 years, there were no deaths related to the stent-graft implantation or to revascularization procedures. Regarding the aortic arch rerouting procedure, there were no pseudoaneurysm or other anastomotic events.

CONCLUSION

Antegrade delivery of the endograft, combined with hybrid and revascularization procedures of the supra-aortic vessels is a safe treatment modality, in complex hostile anatomies. However, further improvements are recommended due to the presence of neurologic complications and reinterventions.

Development of aortic arch surgery in Bologna and reflections on current strategy of cerebral protection

Complications after open arch repair much decreased over time thanks to better methods of organ and cerebral protection. The crossroads was the introduction of antegrade cerebral perfusion as a method of cerebral protection. Other intraoperative techniques also contributed to facilitate arch reconstruction, such as performing circulatory arrest at higher core temperature, using hybrid grafts or endografts, and monitoring cerebral functions during the procedure. As part of this exciting process, we go back in Bologna in the early 1970s to relive some of these fundamental steps on aortic arch surgery. Today a large number of issues on cerebral protection remain for which we have incomplete responses. Probably, a super specialized approach and endovascular techniques will continue to improve the quality of care of patients with different arch pathologies.

Virtual Reality in the Preoperative Planning of Adult Aortic Surgery: A Feasibility Study

Background: Complex aortic anatomy needs careful preoperative planning in which a patient-tailored approach with novel immersive techniques could serve as a valuable addition to current preoperative imaging. This pilot study aimed to investigate the technical feasibility of virtual reality (VR) as an additional imaging tool for preoperative planning in ascending aortic surgery. Methods: Ten cardiothoracic surgeons were presented with six patients who had each undergone a recent repair of the ascending aorta. Two-dimensional computed tomography images of each patient were assessed prior to the VR session. After three-dimensional (3D) VR rendering and 3D segmentation of the ascending aorta and aortic arch, the reconstructions were analyzed by each surgeon in VR via a head-mounted display. Each cardiothoracic surgeon completed a questionnaire after each planning procedure. The results of their assessments were compared to the performed operations. The primary endpoint of the present study was a change of surgical approach from open to clamped distal anastomosis, and vice versa. Results: Compared with conventional imaging, 80% of surgeons found that VR prepared them better for surgery. In 33% of cases (two out of six), the preoperative decision was adjusted due to the 3D VR-based evaluation of the anatomy. Surgeons rated CardioVR usefulness, user-friendliness, and satisfaction with median scores of 3.8 (IQR: 3.5-4.1), 4.2 (IQR: 3.8-4.6,) and 4.1 (IQR: 3.8-4.7) on a five-point Likert scale, respectively. Conclusions: Three-dimensional VR imaging was associated with improved anatomical understanding among surgeons and could be helpful in the future preoperative planning of ascending aortic surgery.

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.

Ketamine Mitigates Neurobehavioral Deficits in a Canine Model of Hypothermic Circulatory Arrest

Hypothermic circulatory arrest is a protective technique used when complete cessation of circulation is required during cardiac surgery. Prior efforts to decrease neurologic injury with the NMDA receptor antagonist MK801 were limited by unacceptable side effects. We hypothesized that ketamine would provide neuroprotection without dose-limiting side effects. Canines were peripherally cannulated for cardiopulmonary bypass, cooled to 18°C, and underwent 90 minutes of circulatory arrest. Ketamine-treated canines (n = 5; total dose 2.85 mg/kg) were compared to untreated controls (n = 10). A validated neurobehavioral deficit score was obtained at 24, 48, and 72 hours (0 = no deficits/normal exam; higher score represents increasing deficits). Biomarkers of neuronal injury in the cerebrospinal fluid were examined at baseline and at 8, 24, 48, and 72 hours. Brain histopathologic injury was scored at 72 hours (higher score indicates more necrosis and apoptosis). Ketamine-treated canines had significantly improved, lower neurobehavioral deficit scores compared to controls (overall P = 0.003; 24 hours: median 72 vs 112, P = 0.030; 48 hours: 47 vs 90, P = 0.021; 72 hours: 30 vs 89, P = 0.069). Although the histopathologic injury scores of ketamine-treated canines (median 12) were lower than controls (16), there was no statistical difference (P = 0.10). Levels of phosphorylated neurofilament-H and neuron specific enolase, markers of neuronal injury, were significantly lower in ketamine-treated animals (P = 0.010 and = 0.039, respectively). Ketamine significantly reduced neurologic deficits and biomarkers of injury in canines after hypothermic circulatory arrest. Ketamine represents a safe and approved medication that may be useful as a pharmacologic neuroprotectant during cardiac surgery with circulatory arrest.

Hybrid Approach in Acute and Chronic Aortic Disease

The management of patients with aortic disease that involves the ascending aorta, the aortic arch, and the descending aorta represent a surgical challenge. Open surgical repair remains the gold standard for aortic arch pathologies. However, this operation requires a cardiopulmonary bypass and a period of profound hypothermia and circulatory arrest, which carries a substantial rate of mortality and morbidity. For these reasons, hybrid arch repair that involves a combination of open surgery with endovascular aortic stent graft placement has been introduced as a therapeutic alternative for those patients deemed unfit for open surgical procedures. Hybrid repair requires varying degrees of invasiveness and can be performed as a single-stage procedure or as a two-stage procedure. The choice of the technique is multifactorial, depending on the characteristics of the diseased arch with regard to position of the stent graft proximal landing zone, patient fitness and comorbid status, as well as surgical expertise and hospital facilities. Among the evolving hybrid procedures is the so-called “frozen” or stented elephant trunk technique. Adapted from the classical elephant trunk technique, this approach facilitates the repair of a concomitant aortic arch and proximal descending aortic aneurysms in a single stage under circulatory arrest. This technique is increasingly being used to treat extensive thoracic aortic disease and has shown promising results.

Current state of hybrid solutions for aortic arch aneurysms

Since its inception in the early 2000s, hybrid arch repair (HAR) has evolved from a novel approach to a well-established treatment modality for aortic arch pathology in appropriately selected patients. HAR procedures have been proposed as a means to circumvent the perioperative morbidity and mortality associated with open total arch replacement. These procedures, all of which remain off-label applications of approved endograft technology, combine more conventional open surgical techniques, to create endograft landing zones, with thoracic endovascular aortic repair to exclude the aortic pathology from the circulation. The current classification system for HAR was proposed in 2013 and consists of three types, designated by the Roman numerals I, II and III. The current system has become outdated, however, with the advent of newer technologies, and herein we propose a new, updated classification system that is more encompassing with regards to the broad array of options available to treat aortic arch disease. Likewise, an institutional algorithm to guide patient and operative selection for HAR is presented. Patients are considered for HAR if they have either high-risk comorbidities or high-risk anatomy, with an important feature of the algorithm being that any decisions about repair strategy should be made by a surgical team with expertise in both open and endovascular techniques. Despite being performed for nearly two decades, the evidence around HAR consists mainly of single center series (level B-C evidence) with no randomized controlled trials. The data suggest HAR to be a safe alternative to open repair with acceptable short and mid-term results. As we as aortic surgeons continue to move towards less invasive approaches, both conventional open and hybrid techniques will remain important tools in the toolbox for arch repair, although the advent of multi-branched arch endografts will almost certainly reduce the extent of open or hybrid repair in many patients and eliminate it altogether in others.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Safety and durability of single-stage type I hybrid total aortic arch repair for extensive aortic arch disease: early- and long-term clinical outcomes from a single center and our 10-year of experience

Background

Single-stage type I hybrid total aortic arch repair is a surgical treatment for extensive aortic arch disease, but the clinical outcomes were distinguishing. The purposes of this study were to share our experience and evaluate the perioperative safety and long-term durability.

Methods

Thirty-six patients who underwent single-stage type I hybrid total aortic arch repair in Fuwai Hospital between January 2010 and June 2020 were respectively reviewed. Early primary endpoint was defined as early composite adverse events, including mortality, multiple organ dysfunction syndrome (MODS), unplanned reoperation, stroke, paraplegia, acute renal failure (ARF) necessitating continuous renal replacement therapy (CRRT), respiratory failure and stents related complications. Long-term endpoints included late mortality, late aortic related reintervention and late adverse aortic events. When evaluating the early- and long-term outcomes, all patients were stratified into two subgroups by age (65 years).

Results

All patients acquired technical success. Early composite adverse events rate was 11.1% (4/36), in-hospital mortality was 8.3% (3/36). Average follow-up period was 48.0±35.3 months. Overall survival rate was 83.3% and 51.9% at 5 and 10 years respectively. Late aortic related reintervention occurred at one (3.0%, 1/33) patient and this patient died after reintervention. Overall freedom from adverse aortic events was 79.2% and 47.5% at 5 and 10 years respectively. Significant difference was not observed between the elderly and young subgroups, no matter in early- and long-term outcomes.

Conclusions

Single-stage type I hybrid total aortic arch repair has achieved desirable outcomes in our center, which does not increase perioperative risk in the elderly patients, meanwhile, also acquire acceptable durability in the young patients. In conclusion, this surgery is a practical mini-invasive treatment for extensive aortic arch disease with strict and limited indications.

[Ascending Aorta and Aortic Arch - Endovascular Therapy Today and in the Future]

Pathologies in the region of the aortic arch may occur in isolation, but adjacent segments of the thoracic aorta - the ascending or descending aorta - are much more commonly affected. The first surgical procedures to treat the aortic arch were performed nearly six decades ago. Despite numerous improvements and innovations in the 20th and early 21st centuries, these procedures are still associated with relevant operative mortality and neurological complication rates. Endovascular techniques and modern hybrid procedures are increasingly expanding the therapeutic spectrum in the aortic arch, although the open surgical approach is currently still the gold standard. Endovascular treatment of aortic aneurysm was first performed in the early 1990s in the infrarenal abdominal aorta. It was not long before the first attempts at endovascular therapy were made for the treatment of the aortic arch. In 1996, Inoue et al. reported the use of the first commonly used endoprosthesis to treat aneurysms in the aortic arch. Continuous improvements and refinements in implantation techniques and also implanted material have resulted in endovascular therapy now being an increasingly important option compared to open surgical procedures in the descending thoracic and abdominal aorta and has partially replaced them as the gold standard. This review article aims to provide an overview of the prerequisites, results, but also limitations of endovascular surgery of the aortic arch.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Early and long-term results of hypothermic circulatory arrest in aortic surgery: a 20-year single-centre experience

AIMS

The aim of this study was to document the postoperative outcomes of patients who underwent hypothermic circulatory arrest (HCA), the evolution of HCA management over time and to identify the risks factor for early mortality and postoperative stroke.

METHODS

Four hundred and twenty-four patients who underwent aortic surgery with HCA at our institution between January 1995 and June 2016 were consecutively included.

RESULTS

The main indications were degenerative aneurysm (254; 59.9%) and acute type A aortic dissection (146; 34.4%). Interventions were performed under deep (18.4 ± 0.9°C; n = 350; 82.5%) or moderate (23.9 ± 1.9°C; n = 74; 17.5%) hypothermia. Antegrade cerebral perfusion (ACP) was employed in 86 (20.3%) cases. The use of moderate hypothermia significantly increased from 2011, to become the preferred strategy in 2016. The in-hospital mortality was 12.5% and the postoperative stroke rate was 7.1%. Kaplan--Meier 5-year survival was 65.7%. Nonelective timing [odds ratio (OR) 4.05; P < 0.001], stroke (OR 3.77' P = 0.032), renal failure (OR 2.49; P = 0.023), redo surgery (2.42; P = 0.049) and CPB time (OR 1.05; P = 0.03) were independent risk factors for in-hospital mortality in multivariate analysis. Femoral cannulation was the only independent risk factor for stroke (OR 3.97; P = 0.002). The level of hypothermia and the use of ACP were not associated with either in-hospital mortality or postoperative stroke.

CONCLUSION

HCA might be widely considered to achieve a radical treatment of the aortic disease, provided that hypothermia is maintained below the 24°C safety threshold and ACP is used for HCA exceeding 30 min, to ensure optimal brain, spinal cord and visceral organs protection.

The role of diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy in monitoring cerebral hemodynamics during hypothermic circulatory arrests

OBJECTIVES

Real-time noninvasive monitoring of cerebral blood flow (CBF) during surgery is key to reducing mortality rates associated with adult cardiac surgeries requiring hypothermic circulatory arrest (HCA). We explored a method to monitor cerebral blood flow during different brain protection techniques using diffuse correlation spectroscopy (DCS), a noninvasive optical technique which, combined with frequency-domain near-infrared spectroscopy (FDNIRS), also provides a measure of oxygen metabolism.

METHODS

We used DCS in combination with FDNIRS to simultaneously measure hemoglobin oxygen saturation (SO2), an index of cerebral blood flow (CBFi), and an index of cerebral metabolic rate of oxygen (CMRO2i) in 12 patients undergoing cardiac surgery with HCA.

RESULTS

Our measurements revealed that a negligible amount of blood is delivered to the cerebral cortex during HCA with retrograde cerebral perfusion, indistinguishable from HCA-only cases (median CBFi drops of 93% and 95%, respectively) with consequent similar decreases in SO2 (mean decrease of 0.6 ± 0.1% and 0.9 ± 0.2% per minute, respectively); CBFi and SO2 are mostly maintained with antegrade cerebral perfusion; the relationship of CMRO2i to temperature is given by CMRO2i = 0.052e0.079T.

CONCLUSIONS

FDNIRS-DCS is able to detect changes in CBFi, SO2, and CMRO2i with intervention and can become a valuable tool for optimizing cerebral protection during HCA.

Review of frozen elephant trunk repair with the Thoraflex Hybrid device

The frozen elephant trunk technique has revolutionized aortic arch repair to enable more extensive arch and descending thoracic aortic treatment in a single setting. We review the current evidence supporting the use of the Thoraflex Hybrid (Terumo Aortic, FL, USA) device and discuss advantages, pitfalls and future design considerations.

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

BACKGROUND

The optimal strategy for cerebral protection during repair of type A acute aortic dissection has yet to be determined. We sought to determine the impact of differing degrees of hypothermia in patients undergoing acute dissection repair.

METHODS

All patients in the International Registry of Acute Aortic Dissection Interventional Cohort database who underwent type A acute aortic dissection repair between 2010 and 2018 were identified. Data for operative temperature were available for 1962 patients subsequently divided into 2 groups according to lowest temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). We then propensity matched 362 pairs of patients and analyzed operative data and short-term outcomes.

RESULTS

The median lowest temperature was 25.0°C in the matched MHCA group as compared with 18.0°C in the DHCA group. For the entire cohort of 1962 patients, in-hospital mortality was 14.2% (278 deaths) but was not significantly different between DHCA and MHCA. The perioperative stroke rate was comparable between groups, before and after propensity matching. Circulatory arrest times were significantly longer in the MHCA cohort, regardless of matching. Use of antegrade or retrograde cerebral perfusion was similar in matched groups. There were no differences in 30-day survival or in other major postoperative morbidity between the 2 matched cohorts.

CONCLUSIONS

A surgical strategy of MHCA + antegrade cerebral perfusion is at least as safe as DHCA during repair of acute type A aortic dissection.

Antegrade and Retrograde Cerebral Perfusion During Acute Type A Aortic Dissection Repair in 290 Patients

AIM

Hypothermia and selective brain perfusion is used for brain protection during an acute type A aortic dissection (ATAAD) correction. We compared the outcomes between antegrade and retrograde cerebral perfusion techniques after ATAAD surgery.

METHOD

Between January 1995 and August 2017, 290 patients underwent ATAAD repair under deep hypothermic circulatory arrest/retrograde cerebral perfusion (DHCA/RCP) in 173 patients and moderate hypothermic circulatory arrest/antegrade cerebral perfusion (MHCA/ACP) in 117 patients. Outcomes of interest were: 30-day mortality, new-onset postoperative neurological complications, and length of intensive care unit (ICU) and in-hospital stays.

RESULTS

No differences were observed between the preoperative details of both groups (p>0.05). Thirty-day (30-day) mortality did not differ between groups (RCP vs ACP, 22% vs 21.4%; p=0.90). New-onset postoperative permanent neurological dysfunctions and coma was similar in two group in 6.9% versus 10.3% of patients and 3.8% versus 6.8% patients of patients, respectively (p=0.69). The incidence of 30-day mortality and new postoperative neurological complications were similar in the RCP and ACP groups (odds ratio [OR], 1.0; 95% confidence interval [CI], 0.39-2.83 [p=0.91] and OR, 1.7; 95% CI, 0.87-3.23 [p=0.11], respectively). There was no difference between length of stay in the ICU and overall stay in hospital between the RCP and ACP groups (p=0.31 and p=0.14, respectively). No difference in survival rate was observed between the RCP and ACP groups (hazard ratio, 1.2; 95% CI, 0.76-2.01 [p=0.39]).

CONCLUSIONS

Thirty-day (30-day) mortality rate, new-onset postoperative neurological dysfunctions, ICU stay, and in-hospital stay did not differ between the MHCA/ACP and DHCA/RCP groups after ATAAD correction. Although the rates of 30-day mortality and postoperative neurological complications were high after ATAAD repair, ACP had no advantages over the RCP technique.

Changing of haemostatic system in a pig model during different types of hypothermic circulatory arrest

BACKGROUND

Hypothermic circulatory arrest is usually used in aortic surgery, congenital heart defect repairs and other complex surgeries. It is frequently associated with excessive postoperative bleeding and the transfusion of allogeneic blood products. The physiopathology of hypothermic circulatory arrest-induced coagulopathy has never been systematically studied. The aim of the study was to investigate this phenomenon in a pig model.

METHODS

Ten pigs were randomly assigned to 30 min of hypothermic circulatory arrest at either 15 °C (n = 5) or 25 °C (n = 5). Detection of apoptosis and haemostatic system assays were performed in this experiment. Enzyme-linked immunosorbent assays were performed at ten time points in each group to study the changes in the coagulation system in hypothermic circulatory arrest. All of the statistical analyses were performed in SPSS software, version 18.0, and as bilateral tests, and p < 0.05 was considered statistically significant.

RESULTS

There was no significant difference in the effect of different types of hypothermic circulatory arrest on routine laboratory tests and tissue sample analysis (p > 0.05, for all). Our results demonstrated that more severe systemic activation of the coagulation system (TAT and F1+2) was applied in the deep hypothermic circulatory arrest group but not in the moderate hypothermic circulatory arrest group (TAT/p = 0.01, F1+2/p = 0.03). However, this activation of the coagulation system (AT III and PC) was not associated with changes in the anticoagulation pathway (AT III/p = 0.24, PC/p = 0.33). In addition, analysis of biomarkers of the haemostatic system revealed that the consumption of coagulation is more concentrated on extrinsic coagulation factors (FVII/p = 0.01).

CONCLUSIONS

Moderate hypothermic circulatory arrest is more suitable for patients with coagulation dysfunction. We believe the application of deep hypothermic circulatory arrest should pay more attention to changes in coagulation rather than the anticoagulation pathway. Extrinsic coagulation factor supplementation is more effective after deep hypothermic circulatory arrest.

Bilateral antegrade cerebral perfusion may be the winner as an adjunct for brain protection

Brain protection during open distal aortic arch replacement surgery is of utmost importance. Hypothermia in combination with cerebral perfusion offers optimal results by maintaining the brain's metabolic supply. Both retrograde cerebral perfusion and antegrade cerebral perfusion, used in combination with hypothermia, produce comparable results when the hypothermic circulatory arrest times are short; in contrast, for longer perfusion times, most aortic surgery centers are trending toward the use of antegrade rather than retrograde cerebral perfusion. Our own preference has been to use a bilateral mode of delivering antegrade cerebral perfusion instead of a unilateral approach, as bilateral perfusion appears to be more protective. We maintain that there is no harm in perfusing both brain hemispheres, so long as an appropriate balloon-tipped catheter is used carefully and manipulation of the head vessels is avoided.

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.

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.