Background

Pulsed-field ablation (PFA) is a nonthermal energy source with high selectivity to myocardial tissue. So far it has been mainly used for pulmonary vein isolation using multipolar catheters. Recently, focal PFA technologies have been launched. No data have been released yet regarding the use of focal PFA for slow-pathway ablation in atrioventricular nodal reentry tachycardia (AVNRT).

Case presentation

We report on a 84-year-old man that presented to our hospital with weekly on-off tachycardia and an ECG documentation of a narrow QRS-complex tachycardia with short RP interval. The patient had no previous cardiac history and echocardiography showed a normal biventricular ejection fraction and absence of significant valvular defects.

Basic PQ interval and AH interval were 260 and 154 ms. A typical slow-fast AVNRT with a CL of 470 ms was easily and reproducibly induced. 3-D map of the tricuspid annulus and coronary sinus (CS) was initially performed using a 8F 3.5 mm-tip Thermocool Smart-Touch catheter and CS angiography was subsequently performed to visualize the CS roof. Later the His bundle and CS roof was tagged on the 3-D map. PFA was applied through a generator (Centauri, Galaxy) delivering a monopolar waveform of 22 Ampere and 2 consecutive cycles. The first application was applied at the anteroinferior CS roof. No junctional beats were observed during the application. AV interval was immediately prolonged after the first application (PR up to 400 ms), then developed to Wenckebach conduction block 2 minutes later and PQ interval returned to 270 ms after 10 minutes. During the application, catheter position was stable under continuously fluoroscopy. The clinical tachycardia was not inducible after a waiting period of 30 minutes. Only one AH-jump and one echo-beat were induced. At one month follow-up the patient had no tachycardia recurrence.

Conclusions

No junctional beats occur during PFA applications at the slow pathway region. However, energy application can result in transient PR prolongation and AV block. Further investigation of the underlying mechanism is warranted.