Concealed left pulmonary vein potentials unmasked by left atrial stimulation

Pulmonary vein potentials (PVPs), though obvious during ectopic activity, a re frequently invisible during sinus rhythm when they need to be distinguis hed from left atrial (LA) potentials to perform successful ablation procedu res. Thirty-six patients with paroxysmal atrial fibrillation underwent circ umferential PV mapping with a circular ten-electrode catheter during sinus rhythm, and during pacing from the right atrium, proximal and distal corona ry sinus (CS), and LA. Ablation was performed at the ostium of the PV, the procedural endpoint consisting of electrical disconnection of the PT from t he LA. A total of 93 PVs (excluding the right inferior PV) were mapped. Dur ing sinus rhythm, distinct right PVPs a were present in all instances, whil e they were concealed within the electrograms recorded from the left inferi or and superior PV in 23 (64%) patients. Distal CS or LA appendage pacing u nmasked and separated left PV from LA potentials by a mean of 19 +/- 14 ms; the LA-to-left-PV potential interval measured 36 +/- 14 ms. The number of deflections also increased from 2.1 +/- 0.7 during sinus rhythm to 3 +/- 1. 4 during LA stimulation. However, in the right superior PV, pacing caused o verlapping of atrial potentials with right superior PVPs. RF ablation of th e left PVPs was performed during distal or LA pacing in 23 patients, while in the right superior PV it was performed during sinus rhythm eliminating a ll, including unmasked, left PVPs, providing proof of their PV origin. Dist al CS or LA pacing is required to recognize left PVPs in approximately 2/3 of patients and facilitates RF ablation.