Identical QRS complexes during atrial fibrillation with aberrant conduction and ventricular tachycardia. The value of a His bundle recording.

In a patient with chronic congestive heart failure, right bundle branch block-shaped QRS complexes occurred in salvos during atrial fibrillation. The site of origin of these complexes could not be determined from the 12-lead ECG alone. Recording of a His bundle electrogram showed that both intraventricular aberrant conduction and ventricular tachycardia were responsible for salvos having the same QRS complexes in the 12-lead ECG.