Twin AV node and induced supraventricular tachycardia in Fontan palliation patients.
BACKGROUND
The coexistence of two distinct atrioventricular (AV) nodes has been described in congenital heart disease requiring Fontan type palliation. The purpose of this study was to evaluate the occurrence of twin AV node according to anatomical subgroups, and to determine its relation to tachycardia.


METHODS
From 2001 to 2003, we performed an electrophysiologic (EP) study upon 52 consecutive patients who had undergone cardiac catheterization after Fontan completion. Atrial pacing was performed at three or more different atrial sites.


RESULTS
In 10/52 patients, two different QRS complexes were recorded at different pacing sites, suggesting twin AV node (9/20 in right isomerism, 1/8 discordance AV connections, 0/24 other complex anomalies). AV reciprocating tachycardia (AVRT), presumably involving two AV nodes and a connecting sling, was induced in 6 of 10 patients who had twin AV node (4/6 used posterior AV node as an antegrade limb, 2/6 used an anterior AV node as an antegrade limb). Heterotaxy syndrome (P < 0.001) and complete AV septal defect (P = 0.002) were found to be risk factors for twin AV node. Junctional tachycardia (JT; HR > 150/min) with either VA dissociation (7/9) or second degree VA block (2/9) were induced by pacing or isoproterenol infusion in 9/52 patients.


CONCLUSIONS
JT induction was associated with a twin AV node (P = 0.04), or a history of early postoperative junctional ectopic tachycardia (P = 0.02). A complicated AV node conduction system such as twin AV node was frequent in heterotaxy syndrome. Both AVRT and JT with VA block may be important causes of tachyarrhythmia in this patient group.
Bae
Eun-Jung
EJ
Department of Pediatrics, Seoul National University Children's Hospital, Seoul, South Korea. eunjbae@plaza.snu.ac.kr
Noh
Chung-Il
CI
Choi
Jung-Yun
JY
Yun
Yong-Soo
YS
Kim
Woong-Han
WH
Lee
Jeong-Ryul
JR
Kim
Yong-Jin
YJ
D000293:Adolescent; D000328:Adult; D001283:Atrioventricular Node / Q000002:abnormalities*; D006328:Cardiac Catheterization; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D018729:Fontan Procedure; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male; D010166:Palliative Care; D011183:Postoperative Complications / Q000503:physiopathology*; D012307:Risk Factors; D013617:Tachycardia, Supraventricular / Q000503:physiopathology*