Mainardi MA, Cioppi F, Marconi M, Sermasi S. Cardiologia 1992 Apr;37(4):297-9. Transesophageal atrial overdrive stimulation is a widely used technique for the interruption of atrial flutter and supraventricular tachyarrhythmias. We describe a case of 60 year old man with a previous myocardial infarction, suffering from angina during effort after aortocoronary bypass who presented several episodes of atrial flutter treated with success by transesophageal atrial overdrive stimulation using swallowing electrodes. During the treatment of the last episode of atrial flutter, after a 5 s burst at 300 b/min ventricular fibrillation occurred and was promptly interrupted by DC shock. This is the first case in our experience and probably the first report of ventricular fibrillation induced by swallowing electrodes. Possible mechanisms as pharmacological interactions, accidental ventricular stimulation, etc, are discussed. In conclusion, even though the risk of dangerous arrhythmias is very low, transesophageal atrial overdrive stimulation should be performed by experts in an equipped room.