Electroanatomic mapping as a supportive tool to map complex postoperative atrial reentrant tachycardias in patients with congenital heart disease

The electrophysiologic approach to post-operative intra-atrial reenty tachycardia is especially challenging in patients with congenital heart disease because the mechanism of the tachycardia is often complex and because the underlying anatomical defect(s) may distort anatomy or support more than one mechanism of tachycardia. Electroanatomic mapping as an adjunct to traditional electrophysiologic study was evaluated in 14 post-operative patients (ages 5–47 years) with congenital heart disease. There were 8 females. All patients had at least one prior surgery for congenital heart disease. The underlying anatomic defects included: Transposition of the great arteries in 3, ASD and/or VSD repair in 3, Tetralogy of Fallot in 3, single ventricle physiology in 2, and other defects in 3 patient(s). Electrophysiologic study and mapping was complemented with electroanatomic mapping in all patients. At least 19 different tachycardias were mapped in 14 patients. Five tachycardias were noted to use the “traditional”, anatomic isthmus. Electroanatomic mapping revealed a different isthmus in the other tachycardias including some that were broad. Anatomic barriers such as the atriotomy site, patches and the site of the pulmonary conduit were identifed which aided in better understanding of the tachycardia and a more thoughtful approach for ablation. We conclude that electroanatomic mapping assisted in identifying an electrophysiologic isthmus, defining the anatomy of distorted atria, supporting delineation of anatomic barriers and areas of silent or no electrical activity and supporting a more strategic approach to ablation of complex post-operative arrhythmias.