Pericaval and periannular intra-atrial reentrant tachycardias in patients with congenital heart disease

Pericaval IART in CHD. Introduction: Intra-atrial reentrant tachycardia (IART) is a frequent late sequel of congenital heart surgery, often involving the cavotricuspid isthmus. In this report, we characterize pericaval reentry, a novel mechanism of isthmus-dependent IART in congenital heart patients, and compare its electrophysiologic characteristics with periannular atrial flutter. Methods and Results: Electrophysiologic and electroanatomic mapping data and acute outcomes were reviewed in postoperative patients with congenital heart disease who underwent electrophysiologic study/radiofrequency catheter ablation at The Children's Hospital, Boston between January 1999 and November 2000. The study included all congenital heart patients with IART and who had undergone (1) the Fontan procedure and (2) a biventricular surgical repair other than atrial switch procedures. Thirty-seven IARTs were mapped in 22 Fontan patients. Twelve of 37 IARTs (33%) that revolved about the inferior vena cava (IVC) and involved the isthmus between the IVC and the tricuspid dimple/right-sided AV valve were identified in 12 patients (48%). Mean pericaval IART cycle length was 332 ± 60 msec (range 240-410). An adjacent or surrounding area of scarring was observed in 10 of 12 IARTs. Slow zones (mean activation latency 39% ± 11% IART cycle length) were detected in 8 of 12 circuits. The boundaries of the zone of slow conduction were scar-low crista (6) and scar-IVC (2). Periannular IART with CL 289 ± 65 ms was observed in 14 of 20 patients with 4-chambered hearts. Slow zones (mean activation latency 28 ± 9% IART cycle length) were found in 8 of 14 circuits. In both forms of IART, the predominant direction of activation of the isthmus was lateral to septal; 83% in pericaval IART and 87% in periannular IART. Radiofrequency catheter ablation successfully terminated 11 of 11 pericaval and 13 of 14 periannular IARTs. Conclusion: Pericaval reentry is a novel and ablatable mechanism of IART in patients specific to the Fontan procedure. It is distinguished from periannular atrial reentry by its association with Fontan anatomy, longer cycle lengths, and occurrence of a prominent discrete zone(s) of slow conduction. Both pericaval and periannular reentry show a marked preference for utilization of the isthmus in a lateral-to-septal direction.