 The treatment of cardiac arrhythmias with endocardial catheter ablation has evolved rapidly over the past few decades. At the time of this writing, the ablation of almost all atrial and ventricular arrhythmias has been described in the literature. Multiple energy modalities e.g. radiofrequency, cryotherapy and approaches e.g. retrograde aortic, transseptal puncture have been described, yet ablation of some rhythms is not as successful as others. 