Decremental Pulmonary Venous Pulse Propagation: Impact for Catheter Ablation in Focal Atrial Fibrillation

Background: Electrical isolation of pulmonary veins (PV's) is crucial to achieve success in catheter ablation for trigger elimination in focal atrial fibrillation (AF). To guide ostial PV radiofrequency (RF) delivery, it is necessary to identify the electrical breakthrough (EBT) between PV and left atrium. For this purpose, coronary sinus (CS) fixed rate pacing is commonly used. This study evaluated, whether CS extrastimulus pacing is superior in identifying the EBT area as compared to fixed rate pacing. Methods: In 9 patients (51 ± 10 years) undergoing a left sided electrophysiological study for AF ablation, 25 PV's (10 right and 15 left-sided PV's) were mapped using a 4 French fixed-wire catheter with eight 6 mm coiled Platinum electrodes in a distal looped configuration (Revelation Helix, Cardima Inc.). For mapping and ablation the electrode loop was positioned in the PV ostium rectangular to the longitudinal PV axis. EBT area was identified as those electrodes indicating the earliest PV signals during CS pacing. We measured number of EBT electrodes and time between EBT and the latest activated bipoles at the electrode loop during fixed rate and extrastimulus pacing. The reduction of two or more EBT electrodes was defined as a significant benefit in EBT identification. Results: In 22 of 25 PV's mapped PV potentials could be observed. Performing fixed rate pacing the EBT area was identified in a mean of 4.2 ± 1 electrodes, whereas using extrastimulus pacing, EBT area could be significantly reduced to 2.3 ± 0.8 electrodes. The time between EBT and latest electrode activated increased from 14 ± 7 ms to 22 ± 10 ms indicating an intrapulmonary conduction delay during extrastimulus pacing. In 13 of 22 PV's mapped (59%), extrastimulus pacing was beneficial in the identification of the EBT, as the primary target for RF delivery. Conclusions: CS extrastimulus pacing induces intra-PV decremental conduction properties allowing one to identify a more localised and smaller EBT area as the primary target for RF delivery. Performing PV ablation to treat focal AF, extrastimulus maneouvers allow to unmask the true EBT and thus may help to limit intrapulmonary RF delivery.     

Case Report: Circumferential Pulmonary Vein Mapping and Ablation in Focal Atrial Fibrillation: Single Catheter Technique

Background: Atrial fibrillation (AF) can be cured in a subgroup of patients performing catheter ablation and eliminate trigger arrhythmias mainly originating in the pulmonary veins (PV's). Case Report: This case report describes the use of a novel catheter design combining both, circumferential mapping and radiofrequency delivery capabilities to perform pulmonary vein ablation in patients with focal AF. It could be demonstrated that this catheter was able to eliminate pulmonary vein potentials in a single left atrial catheter technique without acute evidence for PV stenosis. In two PV's of a second patient, where the Helix catheter was placed in a very ostial position, it was not possible to completely eliminate the PV signal component of the ostial electrogram. Long-term follow-up with AF recurrence documentation will clarify whether ostial PV signal amplitude reduction may serve as an acceptable procedural endpoint. Conclusion: PV potential elimination is feasible using this novel catheter design; safety and long-term efficacy of this single catheter approach will be evaluated in a multicenter study (BITMAP study: Breakthrough and Isolation Trial: Mapping and Ablation of Pulmonary Veins).     

High‐Resolution 3D Scar Imaging Using a Novel Late Iodine Enhancement Multidetector CT Protocol to Guide Ventricular Tachycardia Catheter Ablation

Scar delineation with late gadolinium‐enhanced MRI can direct VT substrate mapping and ablation, but imaging is poor and relatively contraindicated in the majority of patients with ICDs. We present a case of scar definition using late iodine‐enhanced multidetector CT in a patient with ischemic cardiomyopathy and multiple ICD shocks for VT. CT images were acquired using a novel intracoronary contrast delivery protocol which provided high‐resolution subendocardial scar visualization. The segmented scar images were subsequently imported into an electroanatomic mapping platform to guide successful VT ablation.     

Ultra High‐Density Multipolar Mapping With Double Ventricular Access: A Novel Technique for Ablation of Ventricular Tachycardia

Ultra High‐Density Multipolar Mapping With Double Ventricular Access . Background: Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. We describe a technique using double access into the left ventricle for multipolar electroanatomic mapping and ablation of scar‐mediated ventricular tachycardia (VT). Methods: Double access into the left ventricle was obtained via transseptal technique. Endocardial mapping was performed via the first transseptal sheath using a steerable duodecapolar catheter. Higher density mapping was performed in areas of dense scar (<0.5 mV) and border zone (0.5–1.5 mV). All late potentials (LPs) observed on the 20 poles were tagged and pacemapping was performed at these sites for comparison with the clinical or induced VT 12‐lead template. If VT was hemodynamically tolerated, entrainment mapping was attempted at sites demonstrating diastolic activity. Ablation was performed through the second transseptal sheath with an open‐irrigated catheter at target sites identified by LPs, pacemapping, and/or entrainment on the duodecapolar catheter. Results: Seventeen patients (88% ischemic cardiomyopathy) underwent electroanatomic mapping and ablation with double transseptal access. The mean number of endocardial mapping points was 819 ± 357 with an average mapping time of 31 ± 7 minutes. The mean number of VTs induced was 2.8 ± 1.6, mean cycle length 418 ms ± 101. LPs were seen in all patients during endocardial mapping with the duodecapolar catheter. Good (56%) and perfect (44%) pacemaps were seen in all patients when performed. Concealed entrainment, guided by the earliest diastolic activity seen on the duodecapolar catheter, was demonstrated in 4 patients (24%). Acute success was achieved in 94% of patients with complete success in 47% and partial success in 47%. The intermediate success rate (free of VT recurrence) was 69%, with an average follow‐up of 8 ± 3 months. Conclusion: Mapping and ablation of scar‐mediated VT using a multipolar catheter results in ultra high‐density delineation of the left ventricular substrate. A novel double ventricular access strategy has the potential to facilitate identification of LPs, pacemapping, and entrainment mapping. (J Cardiovasc Electrophysiol, Vol. 22, pp. 49‐56, January 2011)