(771) Low Incidence of Seizures in Neonates Following Cardiac Surgery With Cardiopulmonary Bypass

Introduction: Neonates with congenital heart disease (CHD) are at high risk for seizures following cardiopulmonary bypass (CPB). Given the predominance of subclinical seizures, high rate of status epilepticus, and risk of neurologic injury, the American Clinical Neurophysiology Society recommends continuous electroencephalogram (cEEG) monitoring. In 2019, cEEG monitoring was implemented as routine postoperative care in all neonates with CHD who undergo cardiac surgery with CPB at our institution. We aimed to identify the incidence of post-CPB seizures in this cohort.

Methods: We evaluated all neonates ( < 28 days) who underwent CPB at Boston Children's from November 2019-December 2022. cEEG data was collected prospectively. Perioperative characteristics related to cardiac anesthetic, cardiovascular surgical, and cardiac critical care management were retrospectively obtained to evaluate risk factors.

Results: 302 neonates were included. Median age, gestational age, and weight were 4.7 (3.6,7.8) days, 38.9 (37.3,39.3) weeks, and 3.2 (2.7,3.5) kg. 235 (77.3%) were prenatally diagnosed. The most common surgeries were aortic arch repair, Stage 1 palliation (S1P) and arterial switch operation (ASO). Median CPB, cross clamp, circulatory arrest (CA), and CPB times were 174 (140,218), 107 (78, 140;N=97.4%), 4 (2,9;N= 43.4%) and regional perfusion 62 (49,80;N=46.4%) minutes. 47 (15.5%) had a genetic disorder or syndrome. Mortality was 4% (N=12). 91% (N=275) underwent cEEG monitoring for a median of 40 (33,50) hours. 5 (N=1.82%) had seizures without clinical correlate at medians of 30.6 and 28.5 hours post-CPB and post-CICU arrival. Median CPB and CA times in neonates with seizures were 205 (190,232) and 2 (1.5,2.5;N=2) minutes. 4 had preoperative neuroimaging, one significant for right frontoparietal injury. All had postoperative imaging positive for neurologic injury.

Conclusions: To our knowledge, this is the largest study to date reporting post-CPB seizures in neonates with CHD and the lowest reported incidence. It is inadequately powered to evaluate associated perioperative risk factors. A future multicenter study should be performed to assess institutional differences in anesthetic, surgical, and critical care management that increase and decrease the risk of post-CPB seizures in this vulnerable population.