(473) Longitudinal Spectral Power and Heart Rate Variability Derived from EEG: Visualization of Complicated and Uncomplicated Recovery from Pediatric Cardiac Surgery

Rationale: Electrographic seizures occur in approximately 8% of children during the post-operative period following surgical correction of congenital heart disease (CHD). Quantitative EEG (qEEG) is a promising method to identify EEG patterns which may predict seizures or cerebrovascular injury in this population. We used a combination of qEEG and heart rate variability (HRV) to characterize uncomplicated post-surgical recovery in infants with CHD and compared these results to infants with suspected and confirmed neurologic injury including seizures.

Methods: Following surgery, children with high-risk complex CHD underwent up to 48 hours of cEEG recording by institutional protocol. Underlying pathologies included transposition of the great arteries, truncus arteriosus, total anomalous venous return, hypoplastic left ventricle and arch reconstruction.
Patients with confirmed or suspected post-operative neurologic injury were identified from a local pediatric neurocritical care database collected from November 2017 to April 2020. Spectral analysis was accomplished using the discrete Fourier transform (DFT) in clinical sub-bands for F3, F4, C3, Cz, C4, P3, P4 with Laplacian reference on 30-second windows sampled at 256hz with 50% overlap. Heart-rate variability analysis was performed on ECG channels. Estimated Cumulative Density Function (ECDF) density plots were calculated to visually describe the statistical distribution of these data. Poincare plots were produced to evaluate nonlinear characteristics of heart rate variability.

Results: Fifty-seven patients (37% female) were included in the analysis. Of these, 25 had neurocritical care (NCC) consultation for suspected neurologic injury including patients with electrographic seizures and severe abnormal EEG background such as severe suppression and/or asymmetry. 
For time-from-surgery and circadian EEG time series, patients without NCC consultation had higher-amplitude 24-hour cycling of alpha power (Figure 1A), and more focal regions of circadian variability in alpha (Figure 1B). In contrast, patients requiring NCC consultation demonstrated alpha-delta with lower amplitude, less circadian variability and alpha activity which was more scattered throughout the circadian cycle.
For most electrodes, patients requiring NCC consult demonstrated a lower alpha-delta between the 50th and 95th quantiles (Figure 1C). This difference was most evident in the first 0-24 hours following surgery and became less distinguishable in the following 24-48-hour window.
We performed a similar analysis of heart rate variability using Poincare plots (Figure 2). Patients requiring NCC consult (Figure 2 A,B) demonstrated longer inter-beat intervals and discontinuous regions in Poincare space in contrast to control patients with a more uniform ovoid Poincare map (Figure 2 C,D).

Conclusions: These pilot data identify changes in qEEG and HRV parameters during recovery from surgical correction of CHD. While the variability seen between children receiving NCC consult and those without needs to be investigated further, these noted differences may provide early and non-invasive indicators for those patients that may be at risk for neurologic complications, or who may require more targeted neuromonitoring.

Funding: Please list any funding that was received in support of this abstract.: No funding to disclose.