The Classic ‘T on P’ Phenomenon

Congenital long QT syndrome (LQTS) is a genetic channelopathy with variable penetrance characterised by abnormally prolonged ventricular repolarisation with an increased propensity to syncope and polymorphous ventricular tachycardia, which may lead to ventricular fibrillation and sudden cardiac death. Electrocardiography is the primary important step in the diagnosis of LQTS but electrocardiogram (ECG) findings may be easily ignored. We present an asymptomatic two-month-old infant with peculiar ECG features with ‘T on P’ phenomenon caused by a homozygous mutation in the KCNQ1 gene. Implantable cardioverter-defibrillator implantation is an effective therapy and can apply to small children successfully