Author + information
- Received May 30, 2017
- Revision received July 17, 2017
- Accepted July 27, 2017
- Published online September 13, 2017.
- aDepartment of Cardiology, Maimonides Medical Center, Brooklyn, New York
- bBiosense Webster, Inc., Diamond Bar, California
- ↵∗Address for correspondence:
Dr. Felix Yang, Department of Cardiology, Maimonides Medical Center, 4802 Tenth Avenue, Cardiology, 4th Floor, Brooklyn, New York 11219.
Pulmonary vein (PV) isolation is the cornerstone of atrial fibrillation ablation. A critical component of the procedure is verification of the entrance and exit block. Commonly, a multielectrode circumferential or PentaRay catheter (Biosense Webster, Irvine, California) is deployed in a PV to verify the block. Pacing around the bipoles with resultant lack of left atrial capture helps confirm the exit block. When a single or pair of PVs are not isolated, the operator must identify the gap in the circumferential lesion set. Due to variations in vein anatomy and sizes, these multielectrode catheters frequently will not spread across the PV ostium symmetrically, resulting in difficulties in determining the precise location of 1 or more ablation gaps. Rapid assessment of pulmonary vein exit block and location of gap may be achieved by pacing in the PV and its ostia with the ablation catheter at 10 mV at a 2-ms pulse width. A reference signal such as the atrial signal at the mid–coronary sinus catheter is selected, and an activation map is created while pacing from the ablation catheter. In real time, the operator can rove around with the ablation catheter and hone in on the smallest local activation time (i.e., smallest negative local activation time) to find the exact location of the ablation gap (Figure 1, Online Video 1). Only areas where the ablation catheter captures PV or PV antral tissue and advances the coronary sinus signals to the pacing cycle length are acquired for the map. Purple denotes the area of ablation gap because it is the shortest time from the captured tissue to the reference signal. If additional gaps are present, this technique is repeated after ablation to identify the next gap. This technique may also be used for identifying gaps in a posterior box.
Escape mapping allows for more accurate assessment of the region of the ablation gap because measurements are taken to the clean reference signal. In the case of conventional mapping, where pacing is performed from the reference catheter (i.e., the coronary sinus), the system has to annotate signals within the PV and ostia that frequently are fractionated, small, or have double potentials. This results in variation in activation points and inaccuracies in identification of the ablation gap.
For Online Video 1, please see the online version of this paper.
Dr. Yang has received speaking honoraria and consulting fees from Biosense Webster. Mr. Murphy is an employee of Biosense Webster.
- Received May 30, 2017.
- Revision received July 17, 2017.
- Accepted July 27, 2017.
- 2017 American College of Cardiology Foundation