Torsades de pointes following cardioversion: case history and literature review

Abstract

Torsades de pointes (TDP) is a relatively uncommon but potentially fatal cardiac arrhythmia which occurs in patients with long QT syndromes (LQTS). This literature review and case history investigate the causes, symptoms, presentation and treatment of torsades, focusing on drug induced torsades developing after successful cardioversion. In torsades, imbalanced positive ion flows result in early after-depolarisations (EADs) and increased variability in repolarisation rates. These combine to create an unstable re-entrant polymorphic ventricular tachycardia (VT) which can cause patients to suffer symptoms progressing from syncope to ventricular fibrillation (VF) arrest. Typically, torsades has a twisting morphological presentation on rhythm strips due to the irregularity of its re-entry pattern. The arrhythmia is more common in women. Intravenous magnesium is the initial emergency treatment in torsades. The case history illustrates the progressive acquisition of risk factors for drug induced torsades in a patient treated with sotalol following cardioversion. Typical progressive rhythm strip, electrocardiograph (ECG), and QT & corrected QT interval (QTc) interval changes occurring with the arrhythmia are presented.