Abstracts

Rationale: Clinical observations in adult epileptic individuals and experimental studies demonstrate that epilepsy is associated with cardiac changes that may increase the arrhythmogenic potential. Seizures can acutely exert additional arrhythmogenic effects on the heart, manifested as peri-ictal alterations in the ventricular repolarization. Whether altered ventricular repolarization occurs following seizures and status epilepticus (SE) in children, and whether children with epilepsy exhibit more pronounced derangements remains to be fully explored. We hypothesized that altered ventricular repolarization occurs following seizures and SE in children and that altered ventricular repolarization will be more pronounced in children with epilepsy. Methods: We conducted a retrospective study of patients admitted to the pediatric intensive care unit (PICU) at Texas Children's Hospital with the primary diagnosis of seizures or SE between 2011-2013. 12-lead EKG were included in the analysis if: 1) obtained within 24h of PICU admission; 2) not on cardiac medications; 3) no history of heart disease; and 4) no history of ion channel defects. Patients were categorized into control, new onset seizure, and epileptic groups. A blinded cardiac electrophysiologist reviewed all EKG tracings. Corrected QT intervals of 10 consecutive beats were calculated. The stability of ventricular repolarization was assessed by the short-term variability (STV) of the QTc intervals. STV = (∑|QTc_n+1 - QTc_n|)/(N x √2), where |QTc_n+1 - QTc_n| is the absolute difference between the 2 successive beats and N is number of heartbeats. Continuous and categorical variables were analyzed using analysis of variance and Chi square test. Values were expressed as mean±SEM. Results: There were 4681 PICU admissions during the study period, 442 patients were admitted with the primary diagnosis of seizures and SE. From these patients 59 EKGs (28 new onset seizure, 31 epileptic) were included and compared to 28 EKGs from control children. Both seizure groups exhibited more ST segment changes (control: 14%, new onset seizure: 32%, epileptic: 58%, p<0.01) and QRS axis deviation (control: 0%, new onset seizure: 18%, epileptic: 23%, p<0.05). The epileptic group exhibited a higher STV compared to the new onset seizure and control groups (control: 6.5±0.8 ms, new onset seizure: 9.4±0.7 ms, epileptic: 10.1±1.2 ms, p<0.05). Conclusions: Our data suggest that seizures can acutely affect ventricular repolarization as reflected in ST segment changes, QRS axis deviation in the seizure groups. Further, the observation that the epileptic children exhibited more beat-to-beat QTc variability (more STV) compared to the new onset seizure group suggests instability in ventricular repolarization and possibly a propensity for arrhythmias. Our findings provide additional support for seizure-associated cardiac changes and suggest that cardiac alterations already may be present in children with epilepsy. Therefore, seizures and SE acutely may exacerbate the pre-existing ventricular repolarization instability in children with epilepsy leading to potentially lethal arrhythmias.