Perioperative Electroencephalogram Predicts Neurodevelopmental Outcomes in Infants With Congenital Heart Disease

All infants who undergo congenital heart surgery at Cleveland Clinic receive pre- and post-surgical continuous electroencephalogram (CEEG) monitoring, regardless of baseline neurological status. New data suggest that universal adoption of this practice could help mitigate neurodevelopmental injury as these babies grow.

Mitigating long-term neurodevelopmental outcomes

Advances in surgical and perioperative care have significantly improved survival in infants with congenital heart disease. Yet, between 25% and 90% continue to sustain some degree of long-term adverse neurodevelopmental outcomes.

Many centers use magnetic resonance imaging (MRI) to detect neurological injury, but that modality only captures a single moment in time, is expensive, and requires general anesthesia in infants. In contrast, EEG is virtually risk-free. Current use of CEEG is typically limited to the postoperative period and only for infants exhibiting seizures or other neurological symptoms.

“Some babies may not manifest clinical seizures yet have significant abnormalities if you assess them. If you can identify them early and intervene, your chance of rescuing them is much, much higher than if you wait until the child is older and not meeting their milestones,” says Tara Karamlou, MD, MSc, Cleveland Clinic congenital and pediatric heart surgeon and the study’s senior author.

Study design and key findings

Data were examined retrospectively for 218 infants who underwent cardiac surgery at Cleveland Clinic between 2010 and 2021 and who had been assessed with CEEG for 72 hours preoperatively and again for 72 hours after the operation.

The three most common diagnoses in these infants were hypoplastic left heart syndrome, transposition of the great arteries, and arch abnormalities. Norwood procedures, arterial switch operation, and ascending/arch repair were the top three surgeries. In 76 of the infants, Bayley Scales of Infant and Toddler Development, 3rd edition, were collected longitudinally, most often within the first two years after surgery.

Compared to preoperative EEG, postoperative EEG showed significantly greater epileptiform discharges (5.6% vs. 0.49%), evidence of encephalopathy (57% vs. 37%), and any EEG abnormality (78% vs. 60%), all p < 0.05.

Presence of postoperative EEG wave discontinuity predicted lower Bayley cognitive scores. Presence of postoperative theta bursts also predicted lower cognitive scores within the first but not second year after surgery, and also lower Bayley receptive communication scores.

Presence of preoperative EEG wave discontinuity also predicted lower Bayley expressive communication scores, while evidence of dysmaturity on postoperative EEG predicted lower Bayley fine motor scores.

Establishing a baseline and next steps in the research

“The main reason this paper is so important is that we have baseline data, so a true denominator. This way, we’re not subject to ascertainment bias where we’re only doing EEGs when babies have clinical seizures. We know from this study and others that among babies with heart defects, clinical seizures are only the tip of the iceberg,” Dr. Karamlou notes.

No predictive EEG metrics were seen for the Bayley gross motor score. However, deep hypothermic circulatory arrest during surgery did predict lower scores at 1.5 years post-surgery.

The team is currently working to correlate such hemodynamic events throughout the infant’s course of care with later neurologic outcomes. Preliminary data suggest that cumulative time of adverse hemodynamic events may predict fine motor and receptive communication scores.

“We’re now planning to create a dose-response curve for adverse hemodynamic events to include that along with EEG metrics into our predictive model. So, for example, if you have one episode of hypotension or desaturation, that may not cause a neurodevelopmental problem. But if you have three or four, it might. We want to try to correlate those metrics,” Dr. Karamlou says.

Electroencephalogram strategies

The Cleveland Clinic team uses the CEEG data in several ways. One is to counsel parents. “If you know that a baby has a preoperative abnormality, you can counsel the parents that their infant is at higher risk.”

Moreover, “depending on the specific EEG abnormality, we may delay surgery, we may opt for a palliative surgery rather than a complete repair, or we may do a noncardiopulmonary bypass operation, if possible, rather than using cardiopulmonary bypass in order to reduce the risk of brain injury. So, you may modify your surgical plan,” Dr. Karamlou says.

In addition, if nonclinical seizure activity is detected, “you need to treat those aggressively with anti-epileptics, because having seizure activity that is untreated, whether clinical or not, is obviously damaging.”

Cardiac Neurodevelopmental Support Program

If CEEG data indicate an infant is at higher risk for neurologic impairment, families may be interested in utilizing the Cardiac Neurodevelopmental Support Program. The program is staffed with a multidisciplinary team of cardiologists, developmental pediatricians, neurologists, physical and occupational therapists, educational advocates, social workers and other specialists.

Bradley Marino, MD, MBA, study coauthor and Department Chair of Heart, Vascular & Thoracic and Division Chief of Cardiology and Cardiovascular Medicine, leads the program. He notes that data like these provide an opportunity to further personalize care in an intraoperative setting, the ICU, and in longer-term management.

“Our collective goal at Cleveland Clinic Children's is to create a predictive algorithm to identify those babies postoperatively at higher risk for neurological impairments and ensure that we follow these patients closely through the Cardiac Neurodevelopmental Support Program and treat them accordingly,” he says.

Future goals

A prospective study is also in the works. “Our hope is to provide data so that people can go to their hospital administrators and say, ‘Look, we really need to be doing this,’” she concludes.