Abstracts

RATIONALE: Post-transplant seizures are common in infants undergoing cardiac transplant and are usually attributed to hyperperfusion. However, the number of variables potentially contributing to post-transplant seizures is multiple. Identification of these variables may allow for treatment to prevent or more effectively treat these seizures. The aim of this study was to determine specific variables associated with the occurrence and severity of post-transplant seizures in infants with hypoplastic left heart syndrome (HLHS).
METHODS: We reviewed medical records from the pediatric cardiac transplant database, spanning an 11 year period (Jan. 1989 to Dec. 2000). Of 127 HLHS infants, 27 (21%), ages 9 to 175 days, had post-transplant seizures. Patients with pre-transplant seizures were excluded. The control group consisted of 27 age-matched infants without seizures. We compared multiple pre-, intra-, and acute post-transplant variables including birth and growth parameters, time of HLHS diagnosis, maternal variables, circulatory and bypass parameters, laboratory data, neuroimaging, electroencephalographic (EEG) and neurological examination findings, and occurrence of infections or other peri-operative complications. We determined which variables were associated with the occurrence and severity of post-transplant seizures.
RESULTS: Occurrence of post-transplant seizures was associated with the total cardiopulmonary bypass time (CPB) (p=0.004), and to a lesser extent the duration of cooling (p=0.056). None of the other variables were significant. 40% of the patients with seizures required ongoing antiepileptic drug treatment (AED) after discharge. Of those patients with seizures, circulatory arrest time (p=0.04) inversely correlated with the continued need for post-discharge AED use. Pre-transplant EEG abnormalities, higher pre-ictal heart rates, and the presence of post-transplant arrhythmias were associated with the need for post-discharge AEDs (p=0.052, 0.078, and 0.072, respectively), but this did not reach statistical significance. Post-transplant EEGs were not associated with the need for continued AEDs (p=0.696).
CONCLUSIONS: Patients with longer CPB times, especially those with a longer duration of cooling, are at higher risk for the development of post-transplant seizures. Shorter circulatory arrest times are associated with the need for ongoing AEDs. Pre-transplant EEG abnormalities, higher pre-ictal heart rates, and the presence of post-transplant arrhythmias are likely to be predictive of the need for continued AEDs. Our data suggest that certain variables are associated with an increased risk for post-transplant seizures in HLHS infants. This may allow for early intervention to prevent seizures or suggest early aggressive AED treatments. Future studies on modification of transplant techniques to reduce risk variables and to minimize or decrease the severity of post-transplant seizures are also warranted.