Preoperative atrial electrophysiology in pediatric tetralogy of Fallot compared with ventricular septal defect.

BACKGROUND

Atrial arrhythmias are common after tetralogy of Fallot (TOF) repair but are rare after ventricular septal defect (VSD) repair. Although postoperative factors may contribute, preoperative electrophysiological differences could also underlie this differing arrhythmia risk.

OBJECTIVE

The aim of this study was to compare preoperative atrial electrophysiology between pediatric patients with TOF and those with VSD.

METHODS

Intraoperative epicardial mapping was performed in the atria (right atrium, left atrium [LA], pulmonary vein [PV], and Bachmann bundle) of 26 children with TOF and 41 children with VSD. Potential voltage and morphology as well as conduction properties were analyzed.

RESULTS

Despite a lower prevalence of LA dilatation in patients with TOF than in patients with VSD (29% vs 81%, P = .004), TOF exhibited lower potential voltages in the LA and PV (LA: 3.4 ± 1.7 mV vs 5.3 ± 2.5 mV; PV: 1.8 [1.1-5.6] mV vs 4.7 [1.4-8.9] mV, both P < .01) with more low-voltage areas (LA: 12.9% [0.0%-53.7%] vs 4.4% [0.0%-29.0%]; PV: 23.9% [3.6%-47.0%] vs 7.0% [0.0%-35.9%], both P < .01), a higher prevalence of conduction block (LA: 0.6% [0.0%-6.5%] vs 0.0% [0.0%-1.2%], P < .001), and potentials containing 2 deflections (short double potentials: LA, 12.1% [0.5%-41.8%] vs 8.8% [1.3%-18.9%], P = .032; long double potentials: LA, 0.1% [0.0%-13.8%] vs 0.0% [0.0%-2.2%], P = .034).

CONCLUSION

Pediatric patients with TOF have more atrial electrophysiological abnormalities, particularly at the LA and PV, than patients with VSD, suggesting that atrial electrophysiological alterations at these sites are more pronounced in patients with TOF.