RADIOFREQUENCY CURRENT ABLATION OF A MAHA IM FIBER AT THE TRICUSPID ANNULUS

The Mahaim syndrome is a rare variant of accessory pathways. Typically , a normal surface ECG and paroxysmal tachycardias with left bundle br anch block morphology are found. The anatomic correlate is an atrioven tricular or atriofascicular fiber with decremental conduction properti es. Criteria for intracardiac mapping of the atrial insertion of such a fiber include: 1) maximal preexcitation and a short stimulus-QRS int erval with differential pacing from the atrial aspect of the tricuspid annulus, and 2) recording of an accessory pathway potential (''M'' po tential). We report a case of a patient that underwent successful radi ofrequency ablation of a Mahaim fiber at the tricuspid annulus.