Advances in Arrhythmia and Electrophysiology Supravalvular Arrhythmia Identifying and Ablating the Substrate

Mapping and ablating arrhythmias in the great arteries were rarely in the realm of consideration to treat tachyarrhythmias for the first 2 decades of invasive electrophysiology,1 More recently, it has become clear that a variety of arrhythmias including ventricular tachycardia, atrial tachycardia, and accessory pathways can be ablated successfully in the great arteries and the cusps of the semilunar valve.2–5 This set of arrhythmias is associated with a unique set of challenges that need to be overcome to obtain high degrees of success and avoid complications. An understanding of substrate being mapped or ablated is important. Because of the complex relative anatomy of the cardiac valves and great arteries, the electrophysiologist must learn the exact relationship, which is not always intuitive. Equally important is for the operator to correlate the mapped electrograms with fluoroscopy and ultrasound and to repeatedly establish in his or her mind the neighboring structures where arrhythmia may originate and avoid potentially catastrophic complications that may arise from ablation at these locations. Important clues with regard to precise catheter location and the nature of the mapped substrate exist from the electrograms being seen at each site, as well as from details of activation mapping and pace mapping performed at each of these locations. In this article, we will review the regional anatomy of the great arteries and semilunar valves with special emphasis on the arrhythmogenic substrate that may be present at these sites and with regard to avoiding complications as a result of collateral damage. We will then discuss the characteristic electrograms and electrocardiography of the various arrhythmias that are today mapped and ablated above the semilunar valve. Finally, we will provide information on technical details and pitfalls while manipulating catheters and when mapping and delivering energy for ablation at these locations.