Copyright © 2008 Massachusetts Medical Society. After the sudden death of a 13-year-old girl while she was playing basketball, her family comes to the clinic for medical evaluation (Fig. 1). Her parents’ resting electrocardiograms (ECGs) are normal, but her 9-year-old sister’s ECG shows an abnormally long QT interval. There is a history of recurrent syncope in female relatives of the maternal g...

Long QT syndrome (LQTS) is caused by malfunction of cardiac ion channels impairing ventricular repolarization. This predisposes to the development of the polymorphic ventricular tachycardia torsade de pointes (‘twisting of the points’) (Fig. 1). This may either revert spontaneously back to sinus rhythm causing syncope or degenerate to ventricular fibrillation causing sudden death. LQTS can be c...

1272 CMAJ, August 9, 2011, 183(11) © 2011 Canadian Medical Association or its licensors In a First Nation community located northeast of Haida Gwaii in British Columbia, a 38-year-old woman required resuscitation from an apparent cardiac arrest that had occurred while she was coaching at a competitive sports event. She had a history of syncope and palpitations. Her family history included a bro...

P rolongation of the QT interval is a serious electrocardiogram finding because of its association with torsades de pointes and sudden cardiac death. Both congenital and acquired factors can lead to abnormal lengthening of the QT interval. Six types of congenital long QT syndrome (LQT1– LQT6) have been described, each involving mutations in genes encoding potassium or sodium transmembrane chann...