Idiopathic left ventricular tachycardia with a QRS pattern of right bundle branch block and left axis deviation that is sensitive to verapamil is electrophysiologically distinct arrhythmia entity but descriptions in pediatric ages are infrequent. This study attempted to describe the clinical presentation and dignostic clues from the surface ECG in children with idiopathic left venteicular tachycardia.

We retrospectively reviewed the medical records, electrocardiograms, Holter recordings, echocardiographic reports of 10 children with idiopathic left ventricular tachycardia who have been managed at Sejong General Hospital and Asan Medical Center, Seoul, Korea from January 1991 to July 1996. Follow-up periods are 2 months to 5 years(mean=26 months).

1) Age of tachycardia onset was 8 months to 14 years(median=4.3 years). In 3 children tachycardia began from infancy. The main complaint in older children was palpitation and chest discomfort but young childen complained abdominal pain during tachycardia attack. Tachycardia was paroxysmal and sustained. Tachycardia responded to intravenous use of verapamil in 9 patients and was controlled by chronic verapamil medication in 6 patients. 2 patients were well without medication. Radiofrequency catheter ablation was done in an adolescent patient successfully. 2) In sinus rhythm, surface ECG showed normal QRS axis and normal QRS morphologies in all patients. During ventricular tachycardia, the heart rate was 183 to 270 beats/min. The taxhycardia of RBBB morphology was observed in all patients. The mean QRS duration was 109±12ms and the QRS axis was -50° to -90°. Themean RS interval was 60±12ms. AVdissociation was found on surface RCG in all patients and confirmed in 4 patients by transesophageal ECG. We tried rapid transesophageal atrial pacing in 3 patients and could induce and terminate the ventricular tachycardia.

Idiopathic left ventricular tachycaedia is rare in childhood and is seen from infancy. Idiopathic left ventricular tachycardia is generally benign but occasionally causesmyocardial dysfunction. Idiopathic ventricular tachycardia with a QRS pattern of right bundle branch block amd left axis deviation that is sensitive to verapamil in children should not be confused with supraventricular tachycardia with aberrancy and most helpful diagnostic clue is AV dissociation in surface ECG.