From Atrial Fibrillation to Ventricular Fibrillation and Back

A 27-year-old man without any previously known health conditions was found unresponsive on the street after he had been exercising. Cardiopulmonary resuscitation was started by bystanders. On arrival of the emergency services, the rhythm strip in Figure 1A was recorded. It shows an irregular wide-complex tachycardia with different degrees of QRS widening, consistent with preexcited atrial fibrillation with very fast conduction to the ventricles. At the end of the strip, QRS complexes become smaller and erratic as atrial fibrillation turns into ventricular fibrillation. After 4 direct-current shocks (Figure 1B), the ventricles are defibrillated but preexcited atrial fibrillation persists. It is only after 17 shocks and amiodarone administration (Figure 1C) that sinus rhythm is restored. The patient …