Ablation of focal atrial arrhythmia in patients with congenital heart defects after surgery: role of circumscribed areas with heterogeneous conduction.
BACKGROUND
In patients late after surgical repair of congenital heart disease (CHD), areas with abnormal electrophysiologic properties may serve as slow conducting pathways within a macroreentrant circuit or may be the source of focal atrial tachycardia.


OBJECTIVE
The purpose of this study was to evaluate the role of abnormal areas during focal atrial tachycardia prior to ablation.


METHODS
Electroanatomic activation mapping of 62 atrial tachycardias was performed in 43 consecutive patients (37 +/- 12 years) after surgical repair of CHD. The mechanism of atrial tachycardia was scar related intra-atrial reentry (n = 27), cavotricuspid-related atrial flutter (n = 21), atrial fibrillation (n = 2), or focal atrial tachycardia (n = 10). During intra-atrial reentry, channels of slow conduction could be identified in all patients. Subsequent ablation was directed toward connecting two nonconductive borders. The site of origin during focal atrial tachycardia showed fractionated potentials and/or continuous electrical activity.


RESULTS
Ablation directed at isolating the source area resulted in termination of focal atrial tachycardia in all cases. In two patients, ablation of an area showing continuous electrical activity giving rise to fibrillatory conduction resulted in termination of atrial fibrillation. Ablation of intra-atrial reentry was successful in 70%. Atrial flutter and focal atrial tachycardia were successfully ablated in all patients. No complications were observed.


CONCLUSIONS
In patients with surgically corrected CHD, atrial tachycardia most often is caused by a macroreentrant mechanism but in some is the result of a focal mechanism. Areas of abnormal conduction may serve not only as a zone of slow conduction within a macroreentrant circuit but also as the site of origin of a focal atrial arrhythmia. Catheter ablation directed at "source isolation" is effective in eliminating focal atrial tachycardia in patients with CHD.
de Groot
Natasja M S
NM
Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
Zeppenfeld
Katja
K
Wijffels
Maurits C
MC
Chan
Wing King
WK
Blom
Nico A
NA
Van der Wall
Ernst E
EE
Schalij
Martin J
MJ
D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000601:surgery; D001282:Atrial Flutter / Q000601:surgery; D018780:Body Surface Potential Mapping; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D017115:Catheter Ablation; D017097:Electric Impedance; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D006330:Heart Defects, Congenital / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012086:Reoperation; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery; D013612:Tachycardia, Ectopic Atrial / Q000601:surgery; D013617:Tachycardia, Supraventricular / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome