Unusual fibrillation in the emergency department after fall.

47-year-old man with dilated cardiomyopathy, ambulatory left ventricular assist device (Heartmate II, Thoratec Corporation, Pleasanton, CA), and biventricular pacemaker/ implantable cardioverter-defibrillator (ICD) (St. Jude Medical, St Paul, MN) presented with syncope to a local hospital. He was hemodynamically stable and otherwise asymptomatic. His electrolyte panel was unremarkable. Initial ECG diagnosis (Figure 1) was unusual atrial fibrillation. On transfer to our hospital, ventricular fibrillation (VF) was suspected (asterisk in Figure 1), with likely undersensing by a defective ICD resulting in lack of defibrillation and lack of inhibition of atrial-biventricular pacing (arrows). There was pacing noncapture due to VF. The ICD interrogation (left half of Figure 2) revealed persistent VF (asterisk in Figure 2) for 15 hours in duration. There was alternation between polymorphic ventricular tachycardia and coarse VF throughout this period with no evidence of asystole. The patient only lost consciousness during the initial episode on the basis of his recollections and witness accounts. Command defibrillation through the ICD, with the use of the device programmer, could not be performed because of interference by the left ventricular assist device with this particular ICD model, a problem that has been reported previously. Successful external defibrillation resulted in sinus rhythm and biventricular pacing with appropriate capture (right half of Figure 2). During the hospitalization, a new sense/pace lead was implanted to correct the undersensing, and the patient was discharged in good condition.