Unusual fascicular extrasystoles: where is the site of origin?

Radiofrequency ablation for symptomatic, drug refractory premature ventricular contractions has been well established as a treatment modality. Mapping of ventricular ectopy that arises near the native conduction system can be challenging. We report a case of fascicular ectopy arising from the proximal His (H)-Purkinje system that was successfully mapped and ablated. The use of surface and intracardiac electrograms and timing of the His bundle and/or Purkinje potentials is crucial in identifying the exact site of origin.