Electroanatomic characterization of conduction barriers in sinus/atrially paced rhythm and association with intra-atrial reentrant tachycardia circuits following congenital heart disease surgery

Conduction Barriers in Sinus Rhythm and IART, Introduction: The electrophys iologic mechanism of intra-atrial reentrant tachycardia (IART) is generally thought to be a macroreentrant circuit revolving around a nonconductive or highly anisotropic barrier. However, the electrical and anatomic substrate that supports these circuits has been incompletely defined, Our objectives were to characterize the atria of patients with IART using electroanatomic mapping in sinus or atrially paced rhythm and to determine whether electri cal barriers identified in sinus/atrially paced rhythm are associated with IART circuits. Methods and Results: Eighteen patients with IART and a remote history of re paired or palliated congenital heart disease were studied [8 biventricular repair, 8 single ventricle palliation (7 Fontan), and 2 Mustard repair]. Th irteen patients had a right AV valve. In sinus/atrially paced rhythm, elect rical evidence of a crista terminalis was identified in 11 patients, an atr iotomy in 12, and greater than or equal to1 right atrial free-wall scar in 11. In 26 IART circuits characterized, 12 used the right AV valve as a cent ral obstacle, 6 used a right atrial free-wall scar, 3 used an atriotomy, 3 used the crista terminalis, and 2 circuits used an atrial septal scar. All central obstacles used by IART circuits were identified in sinus/atrially p aced rhythm, Conclusion: The crista terminalis, atriotomy, and right atrial scars can be identified in patients with repaired congenital heart disease by electroan atomic mapping in sinus/atrially paced rhythm. These conduction barriers fr equently function as the central obstacle for IART, Demonstration of such f eatures may help focus investigational mapping without reliance on spontane ous initiation of the tachycardia.