Classification of electrophysiological types of atrioventricular nodal re-entrant tachycardia: a reappraisal.

Sequence of retrograde atrial activation is not a reliable criterion for the classification of atrioventricular nodal re-entrant tachycardia (AVNRT) into typical and atypical types. The conventional concept of a lower common pathway is not supported by current evidence and does not represent a reliable or reproducible criterion. The distinction between 'fast-slow' and 'slow-slow' forms is not unanimously defined, and probably of no practical significance. We suggest that AVNRT should be classified as typical or atypical according to the His-atrial interval or, when a His bundle electrogram is not reliably recorded, the ventriculo-atrial interval measured on the His bundle recording electrode.

Lower common pathway location detected by cryoablation of atrioventricular nodal reentrant tachycardia of the common variety.

As different from radiofrequency current energy, cryofreezing energy is able to provide reversible effects on cardiac tissue, called "cryomapping," which enables us to predict the effects of a subsequent application of ablative energy. Cryomapping is able to delineate the anatomical location of the lower common pathway of atrioventricular nodal reentrant tachycardia.

Fast and slow narrow complex tachycardia in one patient: two of a kind?

A 35-year-old female was referred to our hospital. For more than ten years, she had had complaints of two types of paroxysmal palpitations, both with a sudden onset. The first type was rapid and often accompanied by light-headedness; the second she described as much less rapid, better tolerated, and often terminated by the Valsalva manoeuvre. The incidence and duration of both types of paroxysms were increasing. In the emergency room of the referring hospital, the tachycardia was terminated with intravenous verapamil. The electrophysiological study revealed normal conduction parameters. Premature atrial beats (due to catheter manipulation) or delivered atrial extra stimuli over a wide range easily induced two types of tachycardia. AV node modification by radiofrequency ablation using the posterior approach was performed. With this approach, RF ablation of the caudal extension of the AV node is performed, which modifies the slow pathway, so that the reentrant circuit is interrupted. After this intervention, no tachycardia whatsoever could be induced and during followup (8 months), no recurrent arrhythmia of any kind occurred.