Intraoperative Electroencephalogram-Guided Deep Hypothermia Plus Antegrade and/or Retrograde Cerebral Perfusion During Aortic Arch Surgery

Perioperative electroencephalography in cardiac surgery with hypothermic circulatory arrest: a narrative review

OBJECTIVES

Cardiac surgery with hypothermic circulatory arrest (HCA) is associated with neurological morbidity of variable severity and electroencephalography (EEG) is a sensitive proxy measure of brain injury. We conducted a narrative review of the literature to evaluate the role of perioperative EEG monitoring in cardiac surgery involving HCA.

METHODS

Medline, Embase, Central and LILACS databases were searched to identify studies utilizing perioperative EEG during surgery with HCA in all age groups, published since 1985 in any language. We aimed to compare EEG use with no use but due to the lack of comparative studies, we performed a narrative review of its utility. Two or more reviewers independently screened studies for eligibility and extracted data.

RESULTS

Fourty single-centre studies with a total of 3287 patients undergoing surgery were identified. Most were observational cohort studies (34, 85%) with only 1 directly comparing EEG use with no use. EEG continuity (18, 45%), seizures (15, 38%) and electrocerebral inactivity prior to circulatory arrest (15, 38%) were used to detect, monitor, prevent and prognose neurological injury. Neurological dysfunction was reported in almost all studies and occurred in 0-21% of patients. However, the heterogeneity of reported clinical and EEG outcome measures prevented meta-analysis.

CONCLUSIONS

EEG is used to detect cortical ischaemia and seizures and predict neurological abnormalities and may guide intraoperative cerebral protection. However, there is a lack of comparative data demonstrating the benefit of perioperative EEG monitoring. Use of a standardized methodology for performing EEG and reporting outcome metrics would facilitate the conduct of high-quality clinical trials.

Aortic arch repair: lessons learned over three decades at Baylor College of Medicine

The treatment of complex aortic arch disease continues to be among the most demanding cardiovascular operations, with a considerable risk of death and stroke. Since January 1990, our single-practice service has performed over 3000 repairs of the aortic arch. Our aim was to describe the progression of our technical approach to open aortic arch repair. Our center's surgical technique has evolved considerably over the last three decades. When it comes to initial arterial cannulation, we have shifted away from femoral artery cannulation to innominate and axillary artery cannulation. During difficult repairs, this transition has made it easier to use antegrade cerebral perfusion rather than retrograde cerebral perfusion, which was commonly used in the early days. Brain protection tactics during open aortic arch procedures have evolved from profound (≤14 °C) hypothermia during circulatory arrest to moderate (22-24 °C) hypothermia. Aortic arch repair is performed through a median sternotomy and may treat acute aortic dissection, chronic aortic dissection, or degenerative aneurysm. Reoperative repair - that necessitating redo sternotomy - is common in patients undergoing aortic arch repair. The majority of repairs will include varying portions of the ascending aorta and may involve the aortic valve or the aortic root. In some patients, repair may extend into the proximal descending thoracic aorta; this includes elephant trunk, frozen elephant trunk, and antegrade hybrid approaches.

Monitoring cardiac and ascending aortic procedures

Although cardiac and aortic operations have been successfully performed for more than 60 years, the risk of neurologic complications remains high. In particular, the rate of stroke with cardiac operations continues to be significant in the 1%-5% range. Similarly, the risk of stroke with aortic operations remains in the range of 7%-10% despite many years of improving techniques. Because of this persistently high risk, the use of intra-operative neurophysiologic monitoring (IONM) has the potential of improving outcomes. This chapter provides an overview of cardiac/aortic arch procedures from the neurophysiologic standpoint and discusses the roles of different monitoring modalities in detecting injury.

Staged total arch replacement, followed by fenestrated-branched endovascular aortic repair, for patients with mega aortic syndrome

OBJECTIVE

The aim of the present study was to review the clinical outcomes of a staged approach using total arch replacement (TAR) with an elephant trunk or a frozen elephant trunk, followed by fenestrated-branched endovascular aortic repair (F-BEVAR) for patients with mega aortic syndrome.

METHODS

We reviewed the clinical data and outcomes of 11 consecutive patients (8 men; mean age, 71 ± 7 years) treated by staged TAR and F-BEVAR from January 2014 to December 2018. The F-BEVAR procedures were performed under a prospective, nonrandomized, physician-sponsored investigational device exemption protocol. All patients had had mega aortic syndrome, defined by an ascending aorta, arch, and extent I-II thoracoabdominal aortic aneurysm. The endpoints were 30-day mortality, major adverse events (MAE), patient survival, freedom from reintervention, and freedom from target vessel instability.

RESULTS

Of the 11 patients, 6 had developed chronic postdissection aneurysms after previous Stanford A (three A₁₁, two A₁₀, one A₉) dissection repair and 5 had had degenerative aneurysms with no suitable landing zone in the aortic arch. The thoracoabdominal aortic aneurysms were classified as extent I in four patients and extent II in seven. One patient had died within 30 days after TAR (9.0%). However, none of the remaining 10 patients who had undergone F-BEVAR had died. First-stage TAR resulted in MAE in three patients (27%), including one spinal cord injury. The mean length of stay was 12 ± 6 days. The mean interval between TAR and F-BEVAR was 245 ± 138 days with no aneurysm rupture during the interval. Second-stage F-BEVAR was associated with MAE in two patients (20%), including spinal cord injury in one patient from spinal hematoma due to placement of a cerebrospinal fluid drain. The mean follow-up period was 14 ± 10 months. At 2 years postoperatively, patient survival, primary patency, secondary patency, and freedom from renal-mesenteric target vessel instability was 80% ± 9%, 94% ± 6%, 100%, and 86% ± 8%, respectively. No aortic-related deaths occurred during the follow-up period. Four patients had required reintervention, all performed using an endovascular approach.

CONCLUSIONS

A staged approach to treatment of mega aortic syndrome using TAR and F-BEVAR is a feasible alternative for selected high-risk patients. Larger clinical experience and longer follow-up are needed.