Mechanism of sudden cardiac arrest while swimming in a child with the prolonged QT syndrome.

Abstract

We describe the abrupt sequence of events resulting in cardiac arrest while swimming in a 12-year-old with long QT syndrome. Diving into cold water resulted in an irregular cardiac rhythm and further prolongation of the QT interval, followed by a premature ventricular complex, which initiated pulseless ventricular tachycardia (rate >300/minute). The transition from sinus rhythm to ventricular tachycardia occurred in <5 seconds and was followed by a successful implantable cardioverter-defibrillator rescue shock.