Intraoperative care for aortic surgery using circulatory arrest

Cerebral Protection Strategies and Stroke in Surgery for Acute Type A Aortic Dissection

Background: Perioperative stroke remains a devastating complication in the operative treatment of acute type A aortic dissection. To reduce the risk of perioperative stroke, different perfusion techniques can be applied. A consensus on the preferred cerebral protection strategy does not exist. Methods: To provide an overview about the different cerebral protection strategies, literature research on Medline/PubMed was performed. All available original articles reporting on cerebral protection in surgery for acute type A aortic dissection and neurologic outcomes since 2010 were included. Results: Antegrade and retrograde cerebral perfusion may provide similar neurological outcomes while outperforming deep hypothermic circulatory arrest. The choice of arterial cannulation site and chosen level of hypothermia are influencing factors for perioperative stroke. Conclusions: Deep hypothermic circulatory arrest is not recommended as the sole cerebral protection technique. Antegrade and retrograde cerebral perfusion are today’s standard to provide cerebral protection during aortic surgery. Bilateral antegrade cerebral perfusion potentially leads to superior outcomes during prolonged circulatory arrest times between 30 and 50 min. Arterial cannulation sites with antegrade perfusion (axillary, central or carotid artery) in combination with moderate hypothermia seem to be advantageous. Every concept should be complemented by adequate intraoperative neuromonitoring.

Optimal brain protection in aortic arch surgery

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

Anaesthetic-surgical guide in the treatment of ascending aorta and surgery of the ascending aorta and aortic arch. Consensus document of the Spanish Society of Cardiovascular and Endovascular Surgery and the Sociedad of Anaesthesiology, Resuscitation and Pain Therapy

Aortic pathology is always a challenge for the clinician, and must be diagnosed and treated by a multidisciplinary team due to the technical and technological complexity of the resources used. Ongoing efforts to implement a systematic, protocolized approach involving "Aortic teams" made up of cardiologists, cardiac surgeons, vascular surgeons, anaesthesiologists and radiologists, among others are now leading to improved outcomes. The aim of this consensus document drawn up by the Aortic working groups of the Spanish Society of Anaesthesiology, Resuscitation and Pain Therapy (SEDAR) and the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) is to disseminate a set of working protocols. The latest consensus document of the European Association for Cardio-Thoracic Surgery (EACTS) and the European Society for Vascular Surgery (ESVS) define the concept of "AORTIC TEAM"(1). The aortic team should be closely involved from diagnosis to treatment and finally follow-up, and should be formed of cardiac and vascular surgeons working together with anaesthesiologists, cardiologists, radiologists and geneticists. Treatment of aortic pathologies should be centralised in large centres, because this is the only way to effectively understand the natural course of the disease, provide the entire range of treatment options under one umbrella and treat potential complications. A streamlined emergent care pathway (24/7 availability), adequate transportation and transfer capabilities, as well as rapid activation of the multidisciplinary team must be available. In light of the complexity and constant evolution of therapeutic options, we present this first version of the Anaesthesiology and surgical guidelines for surgery of the ascending aorta and aortic arch. Some questions will no doubt remain unanswered, and future versions will include new techniques that, though implemented in some centres, are still not widely recommended.

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.

Deep Hypothermic Circulatory Arrest for Emergency Repair of Type A Aortic Dissection in a Patient with Cold Agglutinins

Cold agglutinins (CA) are auto-antibodies that adhere to erythrocytes in cold temperatures, and can result in agglutination of red blood cells. This process can cause complement-mediated intravascular hemolysis, which can be catastrophic. We describe a patient who developed CA during initiation of deep hypothermic circulatory arrest for emergent repair of Type A aortic dissection. The patient was found to have anti-I and anti-C antibodies and a positive direct Coombs test. CA resolved with re-warming, and resulted in no adverse events.

Anaesthetic-surgical guide in the treatment of ascending aorta and surgery of the ascending aorta and aortic arch. Consensus document of the Spanish Society of Cardiovascular and Endovascular Surgery and the Sociedad of Anaesthesiology, Resuscitation and Pain Therapy

Aortic pathology is always a challenge for the clinician, and must be diagnosed and treated by a multidisciplinary team due to the technical and technological complexity of the resources used. Ongoing efforts to implement a systematic, protocolized approach involving "Aortic teams" made up of cardiologists, cardiac surgeons, vascular surgeons, anaesthesiologists and radiologists, among others are now leading to improved outcomes. The aim of this consensus document drawn up by the Aortic working groups of the Spanish Society of Anaesthesiology, Resuscitation and Pain Therapy (SEDAR) and the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) is to disseminate a set of working protocols. The latest consensus document of the European Association for Cardio-Thoracic Surgery (EACTS) and the European Society for Vascular Surgery (ESVS) define the concept of "AORTIC TEAM"(1). The aortic team should be closely involved from diagnosis to treatment and finally follow-up, and should be formed of cardiac and vascular surgeons working together with anaesthesiologists, cardiologists, radiologists and geneticists. Treatment of aortic pathologies should be centralised in large centres, because this is the only way to effectively understand the natural course of the disease, provide the entire range of treatment options under one umbrella and treat potential complications. A streamlined emergent care pathway (24/7 availability), adequate transportation and transfer capabilities, as well as rapid activation of the multidisciplinary team must be available. In light of the complexity and constant evolution of therapeutic options, we present this first version of the Anaesthesiology and surgical guidelines for surgery of the ascending aorta and aortic arch. Some questions will no doubt remain unanswered, and future versions will include new techniques that, though implemented in some centres, are still not widely recommended.

Hypothermic circulatory arrest time affects neurological outcomes of frozen elephant trunk for acute type A aortic dissection: A systematic review and meta-analysis

BACKGROUND

The treatment of complex thoracic aorta pathologies remains a challenge for cardiovascular surgeons. After introducing Frozen Elephant Trunk (FET), a significant evolution of surgical techniques has been achieved. The present meta-analysis aimed to assess the efficacy of FET in acute type A aortic dissection (ATAAD) and the effect of circulatory arrest time on post-operative neurologic outcomes.

METHODS

A standard Preferred Reporting Items for Systematic Reviews and Meta-Analyses search was conducted for all observational studies of patients diagnosed with ATAAD undergoing total arch replacement with FET reporting in-hospital mortality, bleeding, and neurological outcomes. A random-effect meta-analysis was performed using STATA software (StataCorp, TX, USA).

RESULTS

Thirty-five studies were eligible for the present meta-analysis, including 3211 patients with ATAAD who underwent total arch replacement with FET. The pooled estimate for in-hospital mortality, postoperative stroke, and spinal cord injury were 7% (95% CI 5 - 9; I²  = 68.65%), 5% (95% CI 4 - 7; I²  = 63.93%), and 3% (95% CI 2 - 4; I²  = 19.56%), respectively. Univariate meta-regression revealed that with increasing the duration of hypothermic circulatory arrest time, the effect sizes for postoperative stroke and SCI enhances.

CONCLUSIONS

It seems that employing the FET procedure for acute type A dissection is associated with acceptable neurologic outcomes and a similar mortality rate comparing with other aorta pathologies. Besides, increasing hypothermic circulation arrest time appears to be a significant predictor of adverse neurologic outcomes after FET.

Location of Superior Vena Cava Tears in Transvenous Lead Extraction

BACKGROUND

Superior vena cava (SVC) tears are rare but potentially lethal complications associated with transvenous lead extraction. When lacerations occur, surgeons need to be prepared for an emergent response. Nonetheless, little is known about the precise whereabouts of these lesions. Understanding the location and injury patterns enables a more anticipated and targeted surgical response.

METHODS

We collected data via physician interviews after an SVC laceration occurred. These physicians were identified through the US Food and Drug Administration's Manufacturer and User Facility Device Experience database and independent physician reports of adverse events. We identified 116 reports of SVC tears between July 1, 2016, and July 31, 2018. For an SVC tear to be included in our registry, a cardiothoracic surgeon had to be physically present to confirm the injury via emergent sternotomy. In each case, the surgeon recorded the SVC injury's exact location after a repair was attempted.

RESULTS

During the study period, 116 SVC tears were confirmed by sternotomy. Tears occurred in any combination of the following locations: SVC-innominate vein, body of the SVC, and SVC-right atrial junction. The majority of tears (n = 72; 62%) were located in the isolated body of the SVC, followed by the SVC-right atrial junction (n = 23;19.8%) and the SVC-innominate junction (n = 17;14.6%). Combined tears were rare, accounting for only 3.6% (n = 4) of the adverse events recorded.

CONCLUSIONS

Most SVC tears occurred in the isolated body of the SVC. The second most common location was the SVC-right atrial junction. The SVC-innominate junction was the third most common location for these injuries. Combined tears were uncommon.

Inflammatory profile in a canine model of hypothermic circulatory arrest

BACKGROUND

Hypothermic circulatory arrest (HCA) is a technique used for complex repair of the aorta, but it can be associated with neurologic morbidity. To better understand the molecular changes that underlie ischemic brain injury, we assessed gene expression and cytokine/chemokine polypeptide concentration in brain tissue and cerebrospinal fluid (CSF) of canines that underwent two hours of HCA.

MATERIALS AND METHODS

Adult male canines were cannulated peripherally for cardiopulmonary bypass, cooled to 18°C, and arrested for two hours. Animals were euthanized two, eight, or 24 hours post-HCA (n = 8 per group), and their brains were compared to brains from eight normal canines, using gene expression microarray analysis, cytokine assay, and histopathology.

RESULTS

Two to eight hours after HCA, pro-inflammatory cytokine mRNAs increased markedly, and gene expression was enriched within signaling pathways related to neuroinflammation or ischemic injury. Concentrations of pro-inflammatory cytokine polypeptides IL-6, IL-8, IL-1β, and CCL2 were very low in normal canine brain, whereas anti-inflammatory IL-10 and TGF-β1 were expressed at moderate levels. Pro-inflammatory cytokine concentrations rose robustly in cerebral tissue and CSF after HCA. IL-6 and IL-8 peaked at eight hours and declined at 24 hours, while IL-1β and CCL2 remained elevated. Concentrations of anti-inflammatory IL-10 and TGF-β1 were maintained after HCA, with a significant increase in TGF-β1 at 24 hours.

CONCLUSIONS

These cytokines represent potential diagnostic markers for ischemic neurologic injury that could be used to assess neurologic injury in patients undergoing HCA. The cellular mechanisms underlying this pro-inflammatory, ischemic-induced injury represent potential targets for neuroprotection in the future.

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.

Collateral Circulation in Spinal Cord Injury: A Comprehensive Review

Surgery is the most common cause of spinal cord ischemia; it is also caused by hemodynamic changes, which disrupt the blood flow. Direct ligation of the spinal arteries, especially the Adamkiewicz artery is involved as well. Other causes of spinal cord ischemia include arteriography procedures, thoracic surgery, epidural and rachianesthesia, foraminal infiltration, arterial dissection, systemic hypotension, emboligenic heart disease, thoracic disc herniation, and compression. Understanding the vascular anatomy of the spinal cord is essential to develop optimal strategies for preventing ischemic injuries to the spinal cord. During ischemia, a rich network of intra and paraspinal collaterals allow enough blood flow to compensate the intensity of spinal cord ischemia. In case of interruption of flow of a main artery, the collateral artery increases its flow to maintain perfusion to the tissues. Avoiding spinal cord ischemia by using collateral circulation is necessary to prevent the establishment of hypovolemia, hyperthermia and elevations in venous pressures. The objective of this narrative review is to present the current concepts of spinal collateral circulation and its role in the setting of ischemic events, affecting the vascular supply of the spinal cord.

Current Neurologic Assessment and Neuroprotective Strategies in Cardiac Anesthesia: A Survey to the Membership of the Society of Cardiovascular Anesthesiologists

BACKGROUND

Neurologic injury and cognitive disorder after cardiac surgery are associated with morbidity and mortality. Variability in the application of neuroprotective strategies likely exists during cardiac surgery. The Society of Cardiovascular Anesthesiologists (SCA) conducted a survey among its members on common perioperative neuroprotective strategies: assessment of aortic atheromatous burden, management of intraoperative blood pressure, and use of cerebral oximetry.

METHODS

A 15-item survey was developed by 3 members of the SCA Continuous Practice Improvement - Cerebral Protection Working Group. The questionnaire was then circulated among all working group members, adapted, and tested for face validity. On March 26, 2018, the survey was sent to members of the SCA via e-mail using the Research Electronic Data Capture system. Responses were recorded until April 16, 2018.

RESULTS

Of the 3645 surveys e-mailed, 526 members responded (14.4%). Most responders worked in academic institutions (58.3%), followed by private practices (38.7%). Epiaortic ultrasound for the assessment of aortic atheromatous burden was most commonly utilized at the surgeon's request (46.5%). Cerebral oximetry was most commonly used in patients with increased perioperative risk of cerebral injury (41.4%). Epiaortic ultrasound (1.9%) and cerebral oximetry (5.2%) were rarely part of a standardized monitoring approach. A majority of respondents (52.0%) reported no standardized management strategies for neuroprotection during cardiac surgery at their institution. A total of 55.3% stated that no standardized institutional guidelines were in place for managing a patient's blood pressure intraoperatively or during cardiopulmonary bypass. When asked about patients at risk for postoperative cerebral injury, 41.3% targeted a blood pressure goal >65 mmHg during cardiopulmonary bypass. The majority of responders (60.4%) who had access to institutional rates of postoperative stroke/cerebral injury had standard neuroprotective strategies in place.

CONCLUSIONS

Our data indicate that approximately half of the respondents to this SCA survey do not use standardized guidelines/standard operating procedures for perioperative cerebral protection. The lack of standardized neuroprotective strategies during cardiac surgery may impact postoperative neurologic outcomes. Further investigations are warranted and should assess the association of standardized neuroprotective approaches and postoperative neurological outcomes.

Early Onset of Postoperative Gastrointestinal Dysfunction Is Associated With Unfavorable Outcome in Cardiac Surgery: A Prospective Observational Study

Objective:

The distribution of postoperative gastrointestinal (GI) dysfunction and its association with outcome were investigated in cardiac surgery patients. Gastrointestinal function was evaluated using the Acute Gastrointestinal Injury (AGI) grade proposed by the European Society of Intensive Care Medicine.

Design:

Prospective observational study at a single center.

Setting:

University hospital.

Patients:

Consecutive patients presenting for elective cardiac surgery with extracorporeal circulation (ECC).

Interventions:

None.

Results:

Daily assessment using the AGI grade was performed on the first 3 postoperative days in addition to standard care. For analysis, 3 groups were formed based on the maximum AGI grade: AGI 0, AGI 1, and AGI ≥2. Five hundred and one patients completed the study; 32.7%, 65.1%, and 2.2% of the patients scored a maximum AGI 0, AGI 1, and AGI ≥2, respectively. Patients with AGI grade ≥2 had more frequently undergone thoracic aortic surgery and had longer surgery duration and time on ECC. Patients with AGI grade ≥2 had statistically significant higher frequency of GI complications within 30 days (63.6% vs 1.2% and 5.5% in patients with AGI 0 and AGI 1) and higher 30-day mortality (9.1% vs 0.0% and 1.8% in patients with AGI 0 and AGI 1).

Conclusions:

Early GI dysfunction following cardiac surgery was associated with an unfavorable outcome. Increased attention to GI dysfunction in cardiac surgery patients is warranted and the AGI grade could be a helpful adjunct to a structured approach.

Clinical and Technical Limitations of Cerebral and Somatic Near-Infrared Spectroscopy as an Oxygenation Monitor

Cerebral and somatic near-infrared spectroscopy monitors are commonly used to detect tissue oxygenation in various circumstances. This form of monitoring is based on tissue infrared absorption and can be influenced by several physiological and non-physiological factors that can induce error in the interpretation. This narrative review explores those clinical and technical limitations and proposes solutions and alternatives in order to avoid some of those pitfalls.