Antegrade cerebral perfusion with cold blood: a 13-year experience

Trilateral versus Bilateral Antegrade Cerebral Perfusion in Frozen Elephant Trunk: A Propensity Score Analysis

OBJECTIVE

 Spinal cord injury (SCI) with subsequent paraplegia and/or stroke after arch repair with frozen elephant trunk (FET) remain the most devastating complications. In this study, we aim to examine the impact of different cerebral perfusion strategies on the neurological outcome comparing bilateral antegrade cerebral perfusion (bACP) and trilateral antegrade cerebral perfusion (tACP).

METHODS

 Between 2009 and 2021, 88 patients underwent total arch replacement using a hybrid prosthesis in FET technique for acute (40.4%) and chronic (59.6%) aortic pathologies. After excluding 14 patients who underwent FET with unilateral ACP the remaining 74 patients were divided into two groups. Propensity score matching was performed based on pre- and perioperative patient characteristics resulting in 22 patients in each group. The primary endpoint was a combination of major cerebral event and SCI. Secondary end point was all-cause mortality.

RESULTS

 Major cerebral events occurred in 9% of the patients in bACP versus 13.6% in tACP group (p = 0.63). No postoperative SCI was observed in patients with bACP and only one patient suffered SCI with tACP (p = 0.31). There was no significant difference in 30-day mortality between the two groups (22.7% in bACP vs. 13.6% in tACP; p = 0.43).

CONCLUSION

 In patients undergoing total aortic arch repair using FET technique, both perfusion strategies (bilateral and trilateral ACP) are safe and effective. The rates of neurological complications as well as mortalities are acceptably low in both groups. Further studies with larger patient cohorts are warranted.

Optimal antegrade cerebral perfusion flow in patients undergoing surgery for acute type A aortic dissection: A retrospective single-center analysis

BACKGROUND

Systemic hypothermia with bilateral antegrade selective cerebral perfusion (ASCP) is the preferred cerebral protective strategy for type A aortic dissection surgery. The optimal ASCP flow rate remains uncertain and the target flow cannot always be reached due to pressure limitations. The aim of this study was to assess the correlation between ASCP flow and regional cerebral oxygen saturation (rSO2).

METHODS

A retrospective analysis was performed on 140 patients with acute type A aortic dissection who underwent surgery with moderate hypothermic circulatory arrest and bilateral ASCP between 2015 and 2021. Pearson correlation analysis was performed between ASCP flow and rSO2.

RESULTS

The median circulatory arrest duration was 46.5 (IQR:37.0-61.0) minutes. There was no significant correlation between ASCP flow and rSO2 for both the right (r = -.02, p = .851), and the left hemisphere (r = - .04, p = .618). The rSO2 values for ten patients who received > 10 mL/kg/min flow did not differ significantly from 130 patients who received 10 mL/kg/min or less for both the left hemisphere (p = .135), and the right hemisphere (p = .318). The ASCP flow was 5.1 (IQR:5.0- 6.5) mL/kg/min in five patients with, and 7.2 (IQR:5.8-8.3) mL/kg/min in 135 patients without a watershed infarction (p = .098).

CONCLUSIONS

There was no correlation between ASCP flow rate and rSO2 in patients with acute type A aortic dissection. Furthermore, ASCP flow below 10 mL/kg/min was not associated with a reduction in rSO2. Definitive associations between ASCP flow and neurological outcome after type A aortic dissection surgery need further investigation.

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.

Total arch replacement: When and how?

Acute type A aortic dissection (ATAAD) is a life-threatening disease, which often causes cardiac tamponade, rupture, and malperfusion. ATAAD is associated with a high hospital mortality rate. Open aortic surgery for ATAAD is always required to save the patient, particularly elderly patients. Tear-oriented surgery is recommended as the frontline treatment for ATAAD, and hemiarch replacement (HAR) is sufficient because the primary entry is often observed in the ascending aorta (60%-70%). However, HAR has some drawbacks, such as new creation of an anastomotic entry and unfavorable distal aortic remodeling during long-term follow-up. Although total arch replacement (TAR) is a demanding procedure, it is another useful option for ATAAD. Proper patient selection for TAR is controversial. Standardized procedure for TAR, including the optimal brain protection methods and the use of excellent sealed vascular prosthetic grafts, has been established over the past decades. Therefore, TAR is increasingly being selected for HAR in patients who are young or have enlarged aortic arch, severely dissected supra-aortic arch vessels, or hereditary thoracic aortic disorders. The emerging technology of commercially available frozen elephant trunk accelerated the application of TAR, facilitates distal anastomosis, and improves distal aortic remodeling. Although further evidence is required, TAR could be the best choice for HAR for selected patients. Currently, appropriate selection of the surgical technique is important to maximize the benefits of open surgery for ATAAD.

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.

A simplified isolation technique for atherosclerotic aortic arch aneurysms surgery

The isolation technique is a useful adjunct that prevents atherosclerotic embolism in the brain when the aneurysm is filled with a massive hematoma or 'shaggy aorta'. But the technique is not widespread because of the difficulty in performing the cannulation. We modified this technique by simplifying the cannulation procedure using a puncture method with aortic root cannulas.

Retrograde cerebral perfusion for surgery of type A aortic dissection

BACKGROUND

For type A aortic dissection (TAAD), antegrade cerebral perfusion (ACP) was proposed as a more physiological method than retrograde cerebral perfusion (RCP) for intra-operative brain protection, but it is still debatable whether antegrade cerebral perfusion (ACP) or retrograde cerebral perfusion (RCP) is related to the better clinical outcome. The present study was undertaken to compare the results in our patients receiving surgery for TAAD with ACP or RCP. The primary aim of this study was focused on the incidence of and the factors associated with surgical mortality, post-operative neurological outcomes and long-term survival.

METHODS

From February 2001 to March 2019, there were 223 consecutive patients with TAAD treated surgically at our hospital. The median age at presentation was 56 years (range 29-88 years) and 70 patients (31.4%) over 65 years of age. There were 168 patients treated with RCP and 55 patients treated with ACP. The primary endpoints were surgical mortality and neurological outcome. Propensity score matching was used to compare the treatment results of surgeries with RCP or ACP. The long-term survival was also analyzed.

RESULTS

The overall in-hospital mortality rate and the overall 30-day mortality rate were 15.6% and 14.3% respectively. For the patients without pre-operative shock (n = 184), the in-hospital mortality rate was 10.3% and the 30-day mortality rate was 8.7% and higher long-term survival rates (88.3% for 5 years, 86.5% for 10 years, 86.5% for 15 years) were documented for this patient group. There was no significant difference on the surgical mortality between the ACP group and the RCP group. In the entire cohort, there were 23 patients (10.3%) who suffered from post-operative neurological deficits (PND) and there were less PND for the patients with RCP than the patients with ACP (7.7% vs 18.1%, p = 0.027). After propensity score matching, there was still higher incidence of PND in the ACP group than in the RCP group but without statistical significance (18.5% vs 11.1%, p = 0.279).

CONCLUSIONS

Aortic surgery carries high risk for the patients with TAAD and PND is not an unusual post-operative morbidity. In our series, pre-operative shock, pre-operative CPR, CRI, past history with CAD are related to higher surgical mortality. The younger patients (<65 years old) without pre-operative shock got better surgical outcome and long-term survival. RCP could provide acceptable cerebral protection during aortic surgery for the TAAD patients. Old age, pre-operative shock, CRI and past history of CAD are independent risk factors for long-term survival.

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

Background

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

Methods

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

Results

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

Conclusions

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

A randomized trial comparing axillary versus innominate artery cannulation for aortic arch surgery

BACKGROUND

Cerebral protection remains the cornerstone of successful aortic surgery; however, there is no consensus as to the optimal strategy.

OBJECTIVE

To compare the safety and efficacy of innominate to axillary artery cannulation for delivering antegrade cerebral protection during proximal aortic arch surgery.

METHODS

This randomized controlled trial (The Aortic Surgery Cerebral Protection Evaluation CardioLink-3 Trial, ClinicalTrials.gov Identifier: NCT02554032), conducted across 6 Canadian centers between January 2015 and June 2018, allocated 111 individuals to innominate or axillary artery cannulation. The primary safety outcome was neuroprotection per the appearance of new severe ischemic lesions on the postoperative diffusion-weighted-magnetic resonance imaging. The primary efficacy outcome was the difference in total operative time. Secondary outcomes included 30-day all-cause mortality and postoperative stroke.

RESULTS

One hundred two individuals (mean age, 63 ± 11 years) were in the primary safety per-protocol analysis. Baseline characteristics between the groups were similar. New severe ischemic lesions occurred in 19 participants (38.8%) in the axillary versus 18 (34%) in the innominate group (P for noninferiority = .0009). Total operative times were comparable (median, 293 minutes; interquartile range, 222-411 minutes) for axillary versus (298 minutes; interquartile range, 231-368 minutes) for innominate (P for superiority = .47). Stroke/transient ischemic attack occurred in 4 (7.1%) participants in the axillary versus 2 (3.6%) in the innominate group (P = .43). Thirty-day mortality, seizures, delirium, and duration of mechanical ventilation were similar in both groups.

CONCLUSIONS

diffusion-weighted magnetic resonance imaging assessments indicate that antegrade cerebral protection with innominate cannulation is safe and affords similar neuroprotection to axillary cannulation during aortic surgery, although the burden of new neurological lesions is high in both groups.

A simple method to establish antegrade cerebral perfusion during hemiarch reconstruction

Objective

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

Methods

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

Results

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

Conclusions

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

Early and late outcomes of aortic surgery under hypothermic circulatory arrest in the elderly: a single center study

BACKGROUND

With the progressive aging of the population, aortic surgeons are caring for an increasing number of elderly patients. The objective of this study was to analyze early and late outcomes of aortic surgery with hypothermic circulatory arrest in patients aged 70 and above at our institution.

METHODS

We performed a retrospective cohort study including every patient aged 70 years or older who underwent aortic surgery with hypothermic circulatory arrest between January 1995 and June 2016 at our institution. Operative results were compared with the contemporary younger counterparts aged <70 years. In-hospital mortality and postoperative stroke were primary outcomes of interest. The main secondary outcomes included acute renal failure, reoperation for bleeding, and spinal cord injury.

RESULTS

In the study population, the in-hospital mortality was 16.8% (21/125). Ten (8.0%) patients presented postoperative stroke, and 6 had temporary neurologic disturbance (4.8%). Spinal cord injury occurred in 1 (0.8%) patient. For elective interventions and type A aortic dissections, the in-hospital mortality and stroke rates were 4.6% (3/65) and 7.7% (5/65), 26.8% (11/41) and 12.2% (5/41), respectively. The proportion of non-elective interventions, including type A aortic dissection, and the type of neuroprotective strategy were similar in septuagenarians and younger patients. Patients aged ≥70 had significant shorter cardiopulmonary bypass, myocardial ischemia, and circulatory arrest durations, compared to their younger counterparts. The in-hospital mortality of septuagenarians and younger patients were similar for elective surgery (4.6% vs. 4.7%, P=0.900) and aortic dissections (26.8% vs. 15.1%, P=0.107). There was no statistically significant difference between the two age groups regarding postoperative stroke, spinal cord injury, renal failure requiring dialysis or reintervention for bleeding. Estimated 1-, 3-, and 5-year survival was 78.0%, 70.6%, and 65.7%, respectively. The 5-year survival for elective surgery was 74.9% and 56.0% for non-elective procedures.

CONCLUSIONS

Aortic surgery with circulatory arrest in the elderly demonstrated favorable early and late results when compared with younger individuals, with an acceptable operative risk even under emergency conditions, and should not be denied only because of the chronological age of the patients.

Treatment outcomes for acute type A aortic dissection with patent false lumen in patients over the age of 80

OBJECTIVES

While reports which focus on the outcomes of conservative treatments for acute type A aortic dissection in patients over the age of 80 are worth considering, recently many studies have reported improved outcomes of surgical treatment. Accordingly, we analyzed the outcomes of surgical and conservative treatments for acute type A aortic dissection with patent false lumen in patients over the age of 80.

METHODS

We retrospectively investigated 70 patients over 80 years in age out of 248 consecutive patients with acute type A aortic dissection between January, 2010, and May, 2015. Of the 70 patients, 44 underwent surgical treatments (ascending replacement in 33 and total arch replacement in 11) and 23 patients underwent conservative medical treatments.

RESULTS

In the surgical treatment, the 30-day mortality rate was 14% (6/44) and the rate of morbidity was 34%. And 17 patients (39%) were discharged home without ambulatory assistance. The actuarial survival rates in the surgical treatment group were 83% and 60% at 1 and 3 years, respectively. The in-hospital death rate of conservative medical treatment was 43% (10/23). Only 26% of the patients having had conservative treatment were discharged home without ambulatory assistance. The actuarial survival rate in the conservative medical group was 8.7% at 1 year.

CONCLUSION

Surgical outcomes of acute type A aortic dissection with patent false lumen were satisfactory in patients aged over 80 in this study by meticulously determining operative indications, depending on the background of each patient.

Neuroprotective Strategies in Repair and Replacement of the Aortic Arch

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

Open repair techniques in the aortic arch are still superior

Conventional arch replacement can be carried out in a great majority of patients. Hybrid procedures are often as invasive and technically difficult as conventional ones. Moreover, their immediate results are, in many reported experiences, not better and their long-term results less favourable than the ones observed with conventional methods. So, yes, the open conventional arch replacement is still "the gold standard".

Early results of total arch replacement under partial sternotomy

OBJECTIVE

Partial sternotomy with limited skin incision has been utilized for cardiac surgery. We, therefore, started to apply the partial sternotomy for total arch replacement since 2013 in selected cases. The aim of this study reported the results of our early experiences.

METHODS

Between July 2013 and December 2015, we retrospectively reviewed 15 cases (median age 72, range 67-84, 15 male) who underwent total arch replacement thorough partial sternotomy. All procedures were performed under hypothermic circulatory arrest with selective cerebral perfusion.

RESULTS

Median skin incision was 9 cm (range 7-15 cm, 5.3% of height) and partial sternotomy consisted of 14 upper and 1 lower partial sternotomy (L shape 8 and T shape 7 cases). Median operation time, cardiopulmonary bypass time, ischemic heart time, selective cerebral perfusion time and hypothermic circulatory arrest time were 485 [360-770], 223 [1174-270], 146 [100-163], 154 [116-189], and 69 [45-90] minutes, respectively. Median duration of mechanical ventilator dependent time was 12 h [5-38]. Median length of ICU stay and hospital stay were 3 [1-7], and 18 [13-76] days, respectively. Thirty days and in-hospital mortality were 0% without any neurological complications. There are two aorta-related reoperation due to graft inducing hemolytic anemia and no aorta-related death during follow-up (median 954, range 702-1462 days).

CONCLUSION

The early results of total arch replacement through partial sternotomy were satisfactory. The partial sternotomy could be a good option for total arch replacement in selected patients.

Ascending aorta reinterventions

Ascending aorta reinterventions present a challenge for surgeons as the technical difficulties of the procedure and the complex strategic approach can complicate successful treatment. These patients should be treated by surgical teams with ample experience in aortic diseases as they can be at high risk of mortality. The number of interventions on the ascending aorta and aortic arch and the use of biological conducts (lung autograft, homograft, etc.) have increased in recent years; therefore, the number of reinterventions can also be expected to increase, representing 10% of aortic surgical procedures. This article reviews the current status of ascending aorta reinterventions, analyzing the principal aspects of indication and surgical strategy, as well as the results published in the largest studies.

Axillary versus innominate artery cannulation for antegrade cerebral perfusion in aortic surgery: design of the Aortic Surgery Cerebral Protection Evaluation (ACE) CardioLink-3 randomised trial

INTRODUCTION

Neurological injury remains the major cause of morbidity and mortality following open aortic arch repair. Systemic hypothermia along with antegrade cerebral perfusion (ACP) is the accepted cerebral protection approach, with axillary artery cannulation being the most common technique used to establish ACP. More recently, innominate artery cannulation has been shown to be a safe and efficacious method for establishing ACP. Inasmuch as there is a lack of high-quality data comparing axillary and innominate artery ACP, we have designed a randomised, multi-centre clinical trial to compare both cerebral perfusion strategies with regards to brain morphological injury using diffusion-weighted MRI (DW-MRI).

METHODS AND ANALYSIS

110 patients undergoing elective aortic surgery with repair of the proximal arch requiring an open distal anastamosis will be randomised to either the innominate artery or the axillary artery cannulation strategy for establishing unilateral ACP during systemic circulatory arrest with moderate levels of hypothermia. The primary safety endpoint of this trial is the proportion of patients with new radiologically significant ischaemic lesions found on postoperative DW-MRI compared with preoperative DW-MRI. The primary efficacy endpoint of this trial is the difference in total operative time between the innominate artery and the axillary artery cannulation group.

ETHICS AND DISSEMINATION

The study protocol and consent forms have been approved by the participating local research ethics boards. Publication of the study results is anticipated in 2018 or 2019. If this study shows that the innominate artery cannulation technique is non-inferior to the axillary artery cannulation technique with regards to brain morphological injury, it will establish the innominate artery cannulation technique as a safe and potentially more efficient method of antegrade cerebral perfusion in aortic surgery.

TRIAL REGISTRATION NUMBER

NCT02554032.

Safe Reentry for False Aneurysm Operations in High-Risk Patients

BACKGROUND

In the absence of a standardized safe surgical reentry strategy for high-risk patients with large or anterior postoperative aortic false aneurysm (PAFA), we aimed to describe an effective and safe approach for such patients.

METHODS

We prospectively analyzed patients treated for PAFA between 2006 and 2015. According to the preoperative computed tomography scan examination, patients were divided into two groups according to the anatomy and extension of PAFA: in group A, high-risk PAFA (diameter ≥3 cm) developed in the anterior mediastinum; in group B, low-risk PAFA (diameter <3 cm) was situated posteriorly. For group A, a safe surgical strategy, including continuous cerebral, visceral, and coronary perfusion was adopted before resternotomy; group B patients underwent conventional surgery.

RESULTS

We treated 27 patients (safe reentry, n = 13; standard approach, n = 14). Mean age was 60 years (range, 29 to 80); 17 patients were male. Mean interval between the first operation and the last procedure was 4.3 years. Overall 30-day mortality rate was 7.4% (1 patient in each group). No aorta-related mortality was observed at 1 and 5 years in either group. The Kaplan-Meier overall survival estimates at 1 and 5 years were, respectively, 92.3% ± 7.4% and 73.4% ± 13.4% in group A, and 92.9% ± 6.9% and 72.2% ± 13.9% in group B (log rank test, p = 0.830). Freedom from reoperation for recurrent aortic disease was 100% at 1 year and 88% at 5 years.

CONCLUSIONS

The safe reentry technique with continuous cerebral, visceral, and coronary perfusion for high-risk patients resulted in early and midterm outcomes similar to those observed for low-risk patients undergoing conventional surgery.

Neurophysiological Intraoperative Monitoring During Aortic Arch Surgery

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Optimal temperature management in aortic arch operations

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

Paediatric CPB: Bypass in a High Risk Group

Children and particularly neonates present unique challenges during CPB. Patient age, size, underlying anatomy and surgical strategy influence the perfusion techniques and the construction of the CPB circuit. The normal changes in physiology in the first weeks of life impact upon surgical technique and outcome of repair.

Limited surgical access necessitates alternative cannulation strategies. Deep hypothermia, low flow CPB and circulatory arrest are frequently used. An understanding of the related pathophysiology is therefore required to make the correct choices and to optimise patient outcome.

Rationale for Implementation of Warm Cardiac Surgery in Pediatrics

Cardiac surgery was developed thanks to the introduction of hypothermia and cardiopulmonary bypass in the early 1950s. The deep hypothermia protective effect has been essential to circulatory arrest complex cases repair. During the early times of open-heart surgery, a major concern was to decrease mortality and to improve short-term outcomes. Both mortality and morbidity dramatically decreased over a few decades. As a consequence, the drawbacks of deep hypothermia, with or without circulatory arrest, became more and more apparent. The limitation of hypothermia was particularly evident for the brain and regional perfusion was introduced as a response to this problem. Despite a gain in popularity, the results of regional perfusion were not fully convincing. In the 1990s, warm surgery was introduced in adults and proved to be safe and reliable. This option eliminates the deleterious effect of ischemia-reperfusion injuries through a continuous, systemic coronary perfusion with warm oxygenated blood. Intermittent warm blood cardioplegia was introduced later, with impressive results. We were convinced by the easiness, safety, and efficiency of warm surgery and shifted to warm pediatric surgery in a two-step program. This article outlines the limitations of hypothermic protection and the basic reasons that led us to implement pediatric warm surgery. After tens of thousands of cases performed across several centers, this reproducible technique proved a valuable alternative to hypothermic surgery.

How to Perfuse: Concepts of Cerebral Protection during Arch Replacement

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

Electroencephalography During Hemiarch Replacement With Moderate Hypothermic Circulatory Arrest

BACKGROUND

This study aimed to characterize intraoperative electroencephalography (EEG) during moderate hypothermic circulatory arrest (MHCA) with selective antegrade cerebral perfusion (SACP), which has not been described previously.

METHODS

This was a single-institution retrospective study of patients undergoing aortic hemiarch replacement using MHCA (temperatures <28°C at circulatory arrest [CA]) and unilateral SACP with EEG monitoring from July 1, 2013 to November 1, 2014. The EEG pattern was determined before and immediately after CA, as well as after establishment of SACP. Patient and procedural characteristics and outcomes were determined and compared after stratification by the presence of ischemic EEG changes.

RESULTS

The study included 71 patients. Before CA, 47 patients (66%) demonstrated a continuous EEG pattern, with or without periodic complexes, and 24 (34%) had a burst suppression EEG pattern. Immediately after CA, abrupt loss of electrocerebral activity occurred in 32 patients (45%), suggestive of cerebral ischemia. Establishment of unilateral SACP rapidly restored electrocerebral activity in all but 2 patients. One patient had persistent loss of left-sided activity, which resolved after transition to bilateral SACP. Another patient had persistent global loss of activity and was placed back on cardiopulmonary bypass for further cooling before reinitiation of CA. No significant differences in characteristics or outcomes were assessed between patients with and without loss of EEG activity.

CONCLUSIONS

Nearly half of patients undergoing hemiarch replacement with MHCA/SACP experience abrupt loss of electrocerebral activity after CA is initiated. Although unilateral SACP usually restores prearrest electrocerebral activity, intraoperative EEG may be particularly valuable for the identification of patients with persistent cerebral ischemia even after SACP.

The Bologna experience with the Thoraflex™ hybrid frozen elephant trunk device

ABSTRACT 

Background: We present our initial experience with the frozen elephant trunk using a Thoraflex™ hybrid device for the treatment of the complex thoracic aorta lesions. Materials & methods: Between March 2013 and March 2014, ten patients underwent thoracic aorta surgery using the frozen elephant trunk approach with the Thoraflex hybrid device. Indications for surgery were: residual type A chronic dissection (eight patients), degenerative aneurysm (one patient) and type B chronic aortic dissection (one patient). Selective antegrade cerebral perfusion and moderate hypothermia were used in all cases. Results: In-hospital mortality was 0% and no patients presented with paraplegia, paraparesis or major neurological events. One patient experienced transient ischemic attack. Two patients underwent reoperation for bleeding. All postoperative angiography CT scans confirmed the desired results. Conclusion: Our initial experience demonstrated excellent early results. The Thoraflex hybrid prosthesis with the four-branched arch graft increases the spectrum of techniques available for the surgeon in the treatment of complex diseases of the thoracic aorta.

Direct innominate artery cannulation for selective antegrade cerebral perfusion during deep hypothermic circulatory arrest in aortic surgery

OBJECTIVE

To demonstrate a novel, reproducible, and effective method of direct innominate artery cannulation using a 14 F pediatric venous cannula to establish antegrade cerebral protection (ACP) in patients undergoing aortic surgery that requires an open distal anastomosis or hemiarch replacement.

METHODS

We reviewed prospectively gathered data on all patients who had undergone replacement of the ascending aorta or hemiarch with an open distal anastomosis using deep hypothermic circulatory arrest and direct innominate artery cannulation with a 14 F pediatric venous cannula at our institution. After central cannulation and cooling to 25 °C to 28 °C, all patients had ACP initiated by way of a direct innominate cannula placed over a guidewire.

RESULTS

Fifty patients underwent direct innominate artery cannulation with our technique from 2010 to 2012. The operative mortality was 2% (n = 1), and the rates of neurologic morbidity were acceptable and similar to those with other methods of ACP delivery: stroke (2%, n = 1), seizure (0%, n = 0), and delirium (18%, n = 9). The mean operative time was 31 ± 9, 19 ± 5, 100 ± 39, 141 ± 39, and 259 ± 63 minutes for cooling, circulatory arrest, crossclamp, cardiopulmonary bypass, and total operative time, respectively. No local or arterial complications were observed.

CONCLUSIONS

Direct cannulation of the innominate artery using a 14 F pediatric venous cannula is a simple, reproducible, safe, and effective technique for establishing ACP in patients undergoing aortic surgery that requires an open distal anastomosis or hemiarch replacement. This technique avoids the additional time and potential local complications associated with other established methods for delivering ACP, such as axillary cannulation.

Successful repair of a syphilitic aortic arch aneurysm accompanied by serious cerebral infarction

We present a 52-year-old male with a syphilitic aortic arch aneurysm accompanied by relevant extensive cerebral infarction. He was admitted to a local hospital for sudden loss of consciousness, where he was diagnosed with serious cerebral infarction. During his treatment, a multilocular aortic arch aneurysm involving the arch vessels was found incidentally. He was transferred to our hospital for surgical treatment. A preoperative routine laboratory test for syphilis was highly positive, which suggested that the aneurysm was likely caused by syphilis and the cerebral infarction was also induced by the involvement of syphilitic aortitis or arteritis. After 2 weeks of antibiotic therapy for syphilis, total arch replacement was performed successfully using meticulous brain protection with antegrade selective cerebral perfusion and deep hypothermia. He recovered without any further cerebral deficits. The pathological examination of the surgical specimen showed some characteristic changes of syphilitic aortitis.

Hybrid procedure to treat aortic arch aneurysm combined with aortic arch coarctation and left internal carotid artery aneurysm (Case Report)

Aortic arch aneurysm is a rare condition but carries a high risk of rupture. We report one case of aortic arch aneurysm combined with aortic arch coarctation and left internal carotid artery aneurysm, which is extremely rare. Left internal carotid artery aneurysm resection and revascularization, carotid and carotid graft bypass combined with endovascular stent graft and embolization with coils were successfully performed. There were no any complaints and complications at 8 months follow-up. The follow-up CTA demonstrated thrombus formation in the aneurysm lumen, no endoleak and the aortic arch and bypass graft were all patent. We feel that hybrid procedure may be a valuable therapeutic alternative when treating this type of lesion. However, long-term clinical efficacy and safety have yet to be confirmed.