Electrophysiological breakthroughs from the left atrium to the pulmonary veins

Background-The extent of ostial ablation necessary to electrically disconne ct the pulmonary vein (PV) myocardial extensions that initiate atrial fibri llation from the left atrium has not been determined. Methods and Results-Seventy patients underwent PV mapping with a circumfere ntial 10-electrode catheter during sinus rhythm or left atrial pacing. Afte r assessment of perimetric distribution and activation sequence of PV poten tials, ostial ablation was performed at segments showing earliest activatio n, with the end point of PV disconnection. A total of 162 PVs (excluding ri ght inferior PVs) were ablated. PV potentials were present at 60% to 88% df their perimeter, but PV muscle activation was always sequential from a seg ment with earliest activation (breakthrough). Radiofrequency (RE) applicati on at this breakthrough eliminated all PV potentials in 34 PVs, whereas a s econdary breakthrough required RF applications at separate segments in 77; in others, >2 segments were ablated. A median of 5, 6, and 4 bipoles from t he circular catheter were targeted in the right superior, left superior, an d inferior PVs, respectively, to achieve PV disconnection. Early recurrence of arrhythmia was observed in 31 patients as a result of new venous or atr ial foci or recovery of previously targeted PVs, most related to a single r ecovered breakthrough that was reablated with local RF application. Conclusions-Although PV muscle covers a large extent of the PV perimeter, t here are specific breakthroughs from the left atrium that allow ostial PV d isconnection by use of partial perimetric ablation.