A 62-year-old presents with a ten year history of episodic fast palpitations, which he reports start and end suddenly, and are accompanied by neck pulsations and dyspnea. He reports the palpitations last one to two hours, and have previously needed to be terminated with the injection of IV adenosine. Recently, these episodes have been occuring more frequent (1-2 episodes per month), and so the patient was referred to the Arrhythmia Clinic. While in the waiting room, he develops one of his typical episodes of palpitations:

• Supraventricular tachycardia (AV Nodal Re-entrant Tachycardia)
• Notice the negative P waves “pseudo-S” in the inferior leads and the P waves in aVR, aVL, and V1 closely following the QRS

Vagal stimulation was unsuccessful, and the patient received an IV bolus dose of Adenosine, leading to the restoration of sinus rhythm. The therapeutic options were discussed with the patient, including risks and benefits of catheter ablation, to which he gave consent. The procedure was carried out one month later, and during programmed electrical stimulation, AVNRT was induced. Ablation of the slow pathway was successfully performed, and thereafter AVNRT could no longer be induced: