A very unusual wide QRS tachycardia: VT or SVT?

INTRODUCTION

A 13 old girl presented with recurrent wide QRS tachycardia since she was 4.

METHODS

An electrophysiologic study was performed.

RESULTS

The electrophysiologic study showed that QRS complexes identical to those of the tachycardia could be elicited with premature atrial extrastimuli but with a shorter atrioventricular (AV) delay when the QRS was wide compared with narrow QRS complexes. The tachycardia was ablated at 9 o'clock on the tricuspid annulus demonstrating the presence of an atriofascicular fiber.

CONCLUSION

We believe that this atypical behavior can be explained by AV nodal like longitudinal dissociation of a slowly conducting accessory pathway.