Atypical AV junctional reentrant tachycardia following AV nodal modification.

The authors present a patient who initially underwent anterior approach atrioventricular (AV) nodal modification for treatment of typical AV junctional reentrant tachycardia (AVJRT) and subsequently developed clinical episodes of a previously undocumented type of supraventricular tachycardia. Findings during electrophysiologic studies suggest that this tachycardia is due to both anterograde and retrograde conduction in a slow AV nodal pathway. A "slow pathway" potential was identified and dissociated from the local atrial and ventricular depolarizations. Posterior approach AV nodal modification was successfully used to ablate this tachycardia. These findings suggest that atypical AVJRT occurring after AV nodal modification may be "slow-slow" AVJRT.