Long QT Syndrome in a 10-year Old Boy Presenting with Seizure

Abstract

BACKGROUND: Arrhythmias in children may be benign or life threatening. Some may produce only mild, non-specific symptoms. Thus, specific documentations of arrhythmia, such as electrocardiogram and Holter monitoring, correlated with reported symptoms, are critical in establishing the diagnosis. Long QT syndrome (LQTS) is rare in pediatric patients compared with adults. It may either be inherited or acquired, and results in abnormalities in the ventricular repolarization leading to ventricular arrhythmia, which can be fatal. CASE: This is the case of a 10-year old male who presented for the first time with generalized seizure associated with appearance of arrhythmia during active seizure. Video electroencephalography showed no definite epileptiform discharges. However, there were episodes of ventricular tachycardia (VT) progressing to ventricular fibrillation, with sudden loss of body tone. Electrocardiography showed prolonged corrected QT interval of 0.68 s with T wave alternans. Lidocaine drip was started. Holter monitor showed frequent episodes of T wave alternans, fusion beats and non-sustained polymorphic VT and Torsade des Pointes. With this diagnostic tests pointing to LQTS, he was given propranolol at a dose of 0.5 mg/kg body weight every 6 hours, and phenytoin. There was no recurrence of VT, and seizure was controlled. He was sent home with propranolol and phenytoin as home medication. Genetic testing done on follow-up was consistent with a genetic form of LQTS at gene SCN5A (LQTS3). CONCLUSION: This is the first reported case of a diagnosed LQTS in a pediatric patient at Philippine Heart Center. LQTS is a cardiac electrical disorder. It is often difficult for the families of affected individuals to understand this rare cardiac disease. Seizure is one of the symptoms of LQTS, caused by ventricular arrhythmia and can be fatal. Thus, the importance of obtaining an electrocardiogram in patients with seizure is always emphasized. Genetic testing is recommended to determine the specific genotype as a guide to treatment. Once established, genetic counselling is also recommended to discuss to the family the implications of the disease, and the risk of recurrence.