Successful radiofrequency catheter ablation for macroreentrant ventricular tachycardias in a patient with tetralogy of Fallot after corrective surgery.

Radiofrequency (RF) catheter ablation was applied to two macroreentrant ventricular tachycardias (VTs) documented after corrective operation for tetralogy of Fallot. The activation wavefront of VT with a right bundle branch block pattern was found to revolve in a clockwise manner around a presumed myotomy scar in the right ventricle, and VT with a left bundle branch block pattern revolved around the same anatomical obstacle in a counterclockwise manner. In both VTs, the biggest conduction delay was confirmed at the right ventricular outflow tract. RF applications to the slow conduction area terminated each VT within a few seconds but were insufficient to cure the VTs. RF lesions were then applied to the slow conduction area in a line to intersect the macroreentrant circuit, and both VTs became noninducible.