[Ablation of supraventricular paroxysmal nodal reentrant tachycardia]

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most frequent supraventricular tachycardia. The reentry circuit had been said to be localized within the AV node for many years and the first non pharmacological therapy was the surgical or catheter ablation of the AV node. This was, however, too high a price for a generally well tolerated and non life-threatening arrhythmia. Only recently, the endocardial mapping and the results of surgical perinodal dissection showed that part of the reentry circuit was localized in the atrial myocardium near the AV node. The first approach was the ablation of the fast pathway as it is easier to map during AVNRT. However, this pathway is located very close to the AV node, so that its ablation is complicated by a percentage of AV block that is too high (6.2%) considering the good prognosis of this arrhythmia. In order to reduce this risk, the ablation of the slow pathway which is located more posteriorly and more distant from the AV node, was then proposed. Three different approaches have been suggested; one purely anatomic and the other two guided by electrophysiologic markers. If the posterior and middle part of the septum during sinus rhythm is mapped, more posteriorly, near the coronary sinus os, the sharp potential, described by Jackman, is recorded. It is a sharp spike with a high amplitude, associated with an atrial electrogram of very low amplitude. It cannot be modified by atrial pacing and may also be recorded during the uncommon form of AVNRT.(ABSTRACT TRUNCATED AT 250 WORDS)