Transoesophageal electrophysiological evaluation of paediatric patients with Wolff-Parkinson-White syndrome.

Forty-one consecutive children with the Wolff-Parkinson-White (1-15 years: mean 8 years), 22 symptomatic [including 20 with supraventricular tachycardia (SVT) and one with ventricular fibrillation (VF) episode--Group A) and 19 asymptomatic (Group B)], underwent transoesophageal electrophysiological examination. The mean anterograde effective refractory period of the anomalous connection (AERPAC) was 249 +/- 34 ms with no significant difference between the two groups. However, values of less than 220 ms were more frequently observed in Group A than in Group B (23% vs 11% Pns). The effective atrial refractory period was significantly shorter in Group A (183 +/- 34 ms) than in Group B (220 +/- 24 ms) (P less than 0.02). The refractory period of the AV node was 205 +/- 41 ms in Group A and 244 +/- 63 ms in Group B. Orthodromic SVT was induced exclusively in 75% of Group A patients. Atrial fibrillation (AF) was induced in a total of 46% of patients (45% of Group A, 47% of Group B) and was considered easily induced in 37%. The minimum RR interval between pre-excited beats was significantly shorter in Group A (221 +/- 23 ms) than in Group B (321 +/- 143 ms) (P less than 0.04). Four of the patients in whom AF was easily inducible had an RR interval less than 250 ms; three were symptomatic (one with VF). While the AERPAC is generally short in children, and atrial vulnerability generally slight, 9% of children with a short AERPAC had high atrial vulnerability, thus placing them at risk for life-threatening arrhythmias.