[High frequency catheter ablation in AV-nodal reentry tachycardia: clinical significance of slow pathway potentials and junctional tachycardia].

During slow pathway-ablation of AV nodal reentrant tachycardia (AVNRT) with a mean cycle length of 355 +/- 70 ms the clinical significance of slow pathway electrograms (SP-EGM) and junctional tachycardias (JT) was evaluated in 39 patients (9 male, 30 female; mean age 57 +/- 15 years). After two patients were excluded from further investigation because of inadvertent procedural complete heart block, typical SP-EGM were recorded in 30/37 patients (81%) before successful RF administration in the posteroseptal portion of the right atrium. Signals were recorded 61 +/- 22 and 34 +/- 24 ms after atrial activation in the His bundle and proximal coronary sinus catheter, respectively. Additionally, timing was noted 15 +/- 10 ms before the His spike; the duration of SP-EGM was 27 +/- 7 ms, and the A/V relation of the SP-EGM was calculated as 0.59 +/- 0.51 in the ablation bipole. JT was observed in 24/37 patients (78%), with a mean cycle length of 511 +/- 92 ms. The first tachycardia beat appeared initially 4.1 +/- 3.8 s after delivery of the successful RF administration and lasted 18 +/- 8 s. In 14/37 patients (38%) either SP-EGM or JT was missing; in one patient neither of these two was recorded despite successful ablative therapy. The success rate, defined by noninducibility of AVNRT, was 95% (35/37). In 11% (4/37) AVNRT recurred during a mean follow-up of 5 +/- 4 months. In summary, SP-EGM and JT were recorded reproducibly and proved to be a useful tool as electrographic mapping approach of slow pathway ablation in AVNRT.