The basic science of membrane channels has set in motion striking clinical results, especially in cardiology. The clinical phenotype of cardiac channelopathies is conspicuous; sudden death or cardiac arrest may be the initial presentation. The last 2 decades have changed the face of diagnosis and treatment of inherited channelopathies for families who have a high, and often unrecognized, likeli...

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...

In the interesting article by Viskin et al., adenosine-induced bradycardia was found to produce a higher increase in QT and a lower decrease in QTc (calculated using the Bazett formula) in subjects with long-QT syndrome (LQTS) than in controls. However, a major issue in this study concerns the reliability of QT correction when large ranges of heart rates are analysed. The Bazett formula overcor...