Mechanisms of right atrial tachycardia occurring late after surgical closure of atrial septal defects.
Postatriotomy atrial tachycardia ablation.


BACKGROUND
In patients without structural heart disease, the most frequently occurring AT is the common atrial flutter. In patients with repaired congenital heart disease other mechanisms of AT may occur, due to the presence of an atriotomy that can provide a substrate for reentry. The aim of the present study was to identify the mechanisms of atrial tachycardia (AT) occurring late after atrial septum defect (ASD) repair, with the help of a three-dimensional electroanatomical mapping system.


RESULTS
Twenty-two consecutive patients presenting with AT underwent complete electroanatomic mapping (CARTO, Biosense Webster, Diamond Bar, CA) of spontaneously occurring and inducible right ATs. Complete maps of 26 ATs were obtained. Three tachycardia mechanisms were identified: single-loop macroreentrant atrial tachycardia (MAT) (n=7), double-loop MAT (n=18), and focal AT (n=1). In all MATs, protected isthmuses were identified as the electrophysiological substrate of the arrhythmia, most frequently the cavotricuspid isthmus (CTI) (n=24), and a gap between the inferior vena cava and a line of double potentials (n=11). A mean number of 13.5+/-2.1 radiofrequency applications were delivered to transect these critical parts of the circuit. During a follow-up of 25+/-16 months the RF ablation was acutely successful in all patients. Thirteen patients (59%) had an early recurrence of MAT and needed an additional ablation procedure. One of those patients needed two additional ablation procedures.


CONCLUSIONS
Three-dimensional electroanatomic mapping is useful to identify postsurgical AT mechanisms; the CTI isthmus is involved in 92% MAT, and if the right atrial free wall (RAFW) abnormal tissue related to surgical scar is present this substrate contributes to the MAT circuit.
Magnin-Poull
Isabelle
I
Department of Cardiology, University Hospital Nancy, Nancy, France. i.magnin@chu-nancy.fr
De Chillou
Christian
C
Miljoen
Hielko
H
Andronache
Marius
M
Aliot
Etienne
E
D000328:Adult; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D017115:Catheter Ablation; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria; D006344:Heart Septal Defects, Atrial / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D019233:Retreatment; D013610:Tachycardia / Q000209:etiology* / Q000503:physiopathology* / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome