Seizures in Neonates Undergoing Cardiac Surgery Underappreciated and Dangerous

Summary: In 2011, the American Clinical Neurophysiology Society issued a guideline recommending that neonates undergoing cardiac surgery for repair of congenital heart disease be placed on continuous encephalographic (EEG) monitoring after surgery to detect seizures. These recommendations followed reports that seizures are common in this population, may not be detected clinically, and are associated with adverse neurocognitive outcomes. Yet, in a discussion at the 2014 Annual Meeting of The American Association for Thoracic Surgery, 80% to 90% of the audience was not following these recommendations. In this report from The Children’s Hospital of Philadelphia, investigators present the results of implementing these recommendations. They found that seizures were not uncommon, would not have been detected without EEG monitoring, and that neonates who had seizures faced a significantly higher risk of death.

Newswise — Beverly, MA, August 19, 2015 – With mounting concerns about postoperative seizures, doctors at The Children’s Hospital of Philadelphia placed 161 neonates who had undergone cardiac surgery on continuous EEG monitoring. They found that 8% of the neonates experienced EEG seizures and 85% of these were unrecognized clinically. Many of the seizures were severe, and the seizure group faced a higher risk of death, according to a report in The Journal of Thoracic and Cardiovascular Surgery, the official publication of the American Association for Thoracic Surgery (AATS).

“In their article, Naim and colleagues have clearly pointed out that if we don’t carefully assess for seizure activity with EEG monitoring, we will not identify these at-risk neonates,” stated Carl L. Backer, MD, Division of Cardiovascular-Thoracic Surgery, and Bradley S. Marino, MD, MPP, MSCE, Division of Cardiology, both at the Ann & Robert H. Lurie Children’s Hospital of Chicago, in an accompanying editorial. “It is clearly no longer adequate for investigators reporting outcomes after neonatal cardiac surgery to state that neonates did not have postoperative neurologic complications if they do not use continuous EEG monitoring.”

Conducting a quality improvement project, the team at The Children’s Hospital of Philadelphia implemented continuous EEG monitoring in neonates ( 30 days corrected gestational age) following cardiac surgery for repair of congenital heart disease. During an 18-month period from June 15, 2012 to December 31, 2013, records of continuous EEG (CEEG) were obtained from 94% (161) of 172 surgeries.

CEEG began within six hours of the patient returning to the cardiac intensive care unit after surgery. Monitoring continued for 48 hours if no seizures were detected and for 24 hours after the last seizure if a seizure occurred. EEG technologists were present for EEG monitoring and interpretation at all times.

The neonates had a range of cardiac defects, with 42% class I (two ventricles with no aortic arch obstruction), 22% class II (two ventricles with aortic arch obstruction), 9% class III (single ventricle with no aortic arch obstruction), and 27% class IV (single ventricle with aortic arch obstruction). A variety of repairs were performed, including stage I Norwood (27%) and arterial switch operations (16%).

Bedside clinicians identified events such as abnormal body movements, hypertension, or tachycardia in 32 neonates – but none of these events had associated abnormal EEG activity. However, 13 of the 161 neonates (8%) had EEG seizures. Of these, 85% (11) were not detected clinically. “This indicates that bedside clinical assessment for seizures without CEEG is unreliable,” explained lead investigator Maryam Y. Naim, MD, Division of Cardiac Critical Care, Departments of Anesthesiology and Critical Care Medicine and Pediatrics, The Children’s Hospital of Philadelphia, and Assistant Professor, Perelman School of Medicine at the University of Pennsylvania.

When seizures occurred, they were severe. Sixty-two percent of the neonates with seizures experienced status epilepticus, a dangerous condition in which either a single seizure lasts more than 30 minutes or recurrent seizures together last for more than 30 minutes within a one-hour block.

Dr. Naim and colleagues found that the occurrence of seizures in this patient group was “ominous because 38% (5/13) of neonates with postoperative seizures died” (compared to 3% of those who did not have seizures). Indeed, seizures appear to be a marker of brain injury, since many of those with seizures had diffuse or multifocal lesions apparent on MRI or ultrasound. In the editorial, Dr. Backer and Dr. Marino commented, “Although this may have been a result of increased severity of disease and comorbidities, the prevention of postoperative seizures is still an important goal, which can only be achieved if we monitor for seizures and then use assessment of various surgical and postoperative management strategies to eliminate the development of seizures.”

The investigators looked for predictors of seizure occurrence. They found that surgical factors such as delayed sternal closure and longer deep hypothermic circulatory arrest duration were associated with an increased seizure risk. Seizures were also more frequent in neonates who subsequently required extracorporeal membrane oxygenation or experienced cardiac arrest.

Dr. Naim believes that postoperative CEEG is warranted to identify seizures because they are associated with worse neurodevelopmental outcomes. Recognizing seizures opens treatment with medications or other therapies to reduce seizure occurrence. Dr. Naim acknowledged that there is a lack of high-level data demonstrating that seizure treatment can improve outcomes in high-risk children, such as those undergoing cardiac surgery. However she cited the findings of the Boston Circulatory Arrest Study that showed that postoperative seizure occurrence was the medical variable most consistently related to worse long term neuropsychologic outcomes.

Dr. Backer and Dr. Marino raise another pragmatic issue: the costs and manpower required for CEEG, such as EEG technologists 24/7 and use of comprehensive 12-scalp electrode monitoring. “This level of sophisticated monitoring, of course, is not available at all institutions. What we need is a screening tool that is not as labor intensive. This would remove the expense and staffing associated with full EEG monitoring for the 92% of patients who do not have seizures.”

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NOTES FOR EDITORS“Subclinical seizures identified by postoperative electroencephalographic monitoring are common after neonatal cardiac surgery,” by Maryam Y. Naim, MD, J. William Gaynor, MD, Jodi Chen, MD, Susan C. Nicolson, MD, Stephanie Fuller, MD, Thomas L. Spray, MD, Dennis J. Dlugos, MD, Robert R. Clancy, MD, Livia Vianez Costa, MD, Daniel J. Licht, MD, Rui Xiao, PhD, Heather Meldrum, RN, and Nicholas S. Abend, MD (DOI: http://dx.doi.org/10.1016/j.jtcvs.2015.03.045). Author contact: Joey McCool Ryan, The Children’s Hospital of Philadelphia at 267-426-6070 or [email protected]

ABOUT THE JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERYThe Journal presents original, exclusive articles on conditions of the chest, heart, lungs, and great vessels where surgical intervention is indicated. An official publication of the American Association for Thoracic Surgery and the Western Thoracic Surgical Association, the journal focuses on techniques and developments in cardiac surgery, lung and esophageal surgeries, heart and lung transplantation, and other procedures. Published by Elsevier, it has a current Impact Factor of 4.168 (2014 Journal Citation Reports, ©2015 Thomson Reuters). www.jtcvsonline.org

ABOUT THE AMERICAN ASSOCIATION FOR THORACIC SURGERY (AATS)The American Association for Thoracic Surgery (AATS) is an international organization of over 1,300 of the world’s foremost thoracic and cardiothoracic surgeons, representing 41 countries. AATS encourages and stimulates education and investigation into the areas of intrathoracic physiology, pathology and therapy. Founded in 1917 by a respected group of the last century’s earliest pioneers in the field of thoracic surgery, the AATS’ original mission was to “foster the evolution of an interest in surgery of the Thorax.”

One hundred years later, the AATS continues to be the premiere association among cardiothoracic surgeons. The purpose of the Association is the continual enhancement of the ability of cardiothoracic surgeons to provide the highest level of quality patient care. To this end, the AATS encourages, promotes, and stimulates the scientific investigation and study of cardiothoracic surgery. Visit www.aats.org.