Vein of Marshall chemical ablation decreases atrial fibrillation drivers detected by CARTOFINDER.

INTRODUCTION: This study sought to elucidate the impact of vein of Marshall (VOM) chemical ablation on atrial fibrillation (AF) drivers by investigating the changes in CARTOFINDER mappings before and after VOM chemical ablation in patients with persistent AF. METHODS: This study included 23 consecutive patients undergoing catheter ablation for long-persistent AF (>18 months). VOM chemical ablation was performed following pulmonary vein isolation. CARTOFINDER and AF cycle length (AFCL) maps were created in the left atrium (LA) before and after VOM chemical ablation. The LA was divided into 8 segments, and the number of focal activation points with 6 or more repetitions was counted in each segment. RESULTS: The number of focal activation points was largest in the LA appendage (LAA). After VOM chemical ablation, the number of focal activation points in the LA decreased significantly (37 [interquartile range, IQR: 19-55] vs. 15 [IQR: 7-21], p < .001), and median AFCL was significantly prolonged (159 [147-168] vs. 164 [150-173] ms, p < .001). In the assessment of each segment, significant decreases in focal activation points were observed in the inferior, lateral, and anterior segments and LAA. Among the focal activation points disappearing after chemical ablation, the number in the non-ethanol-affected area was significantly larger than that in the affected area (13 [8-25] vs. 4 [1-10], p < .001). CONCLUSIONS: VOM chemical ablation decreases AF drivers detected by CARTOFINDER. Mechanisms other than direct myocardial damage are considered to contribute the attenuation of AF drivers.

Impact of Interatrial Epicardial Connections on the Dominant Frequency of Atrial Fibrillation.

BACKGROUND: An epicardial connection (EC) between the right-sided pulmonary venous (RtPV) carina and right atrium (RA) may preclude PV isolation, but its electrophysiological role during atrial fibrillation (AF) remains unknown.Methods and Results: This prospective observational study included 98 consecutive patients undergoing catheter ablation for AF, subdivided into the EC group (n=17) and non-EC group (n=80) based on observation of RA posterior wall breakthrough during RtPV pacing. Mean left atrial (LA) dominant frequency (mean DFLA) was defined as the averaged DFs at the right and left PVs and LA appendage. The regional DF was higher in the EC group vs. the non-EC group except at the left PV antrum. The DF at the RA appendage (RAA) and mean DFLAwere equivocal (6.5±0.7 vs. 6.6±0.7 Hz) in the EC group, but the mean DFLAwas significantly higher than that at the RAA (5.8±0.6 vs. 6.1±0.5 Hz, P=0.001) in the non-EC group, suggesting an LA-to-RA DF gradient. A significant correlation of DF between the RtPV antrum and RAA was observed in the EC group (P<0.001, r=0.84) but not in the non-EC group. CONCLUSIONS: An electrophysiological link via interatrial ECs might attenuate the hierarchical nature of activation frequencies of AF, leading to advanced electrical remodeling of the atria.

A simple pacing maneuver to unmask an epicardial connection involving the right-sided pulmonary veins.

INTRODUCTION: An epicardial connection (EC) between the right-sided pulmonary venous (PV) carina and right atrium (RA) is one of the mechanisms for which carinal ablation is required for right-sided PV isolation. The purpose of the study was to devise a simple pacing maneuver to differentiate an EC from a residual conduction gap on the antral ablation line during radiofrequency catheter ablation. METHODS AND RESULTS: This study included 133 consecutive patients. After one round of ablation, electrograms at the posterior antrum outside the ablation line were recorded during sinus rhythm (SR) and coronary sinus (CS) pacing, and intervals between the antral and PV potentials were measured in each rhythm. The ΔintervalSR-CS was calculated as the difference between the interval during SR and that during CS pacing. Presence of an EC was confirmed by observation of a RA posterior wall breakthrough during right-sided PV pacing, which was then targeted for ablation. Patients with nonachievement of first-pass isolation (N = 35) and with PV reconnection during the procedure (N = 9) were classified into the EC-group (N = 20) and gap-group (N=24), respectively. The prevalence of carina breakthrough during SR was higher in the EC-group than the gap-group (18 [95%] vs. 1 [4%] patients, p < .0001). The ΔintervalSR-CS was larger in the EC-group versus gap-group (71 [interquartile range, 57-97] vs. 6 [2-9] ms, p < .0001). In all patients with an EC, RA ablation resulted in delay (32 [20-40] ms) (N = 15) or elimination of PV potentials (N = 5). CONCLUSION: An EC can be efficiently discriminated from a conduction gap by a simple pacing maneuver.

Oral caffeine intake amplifies the effect of isoproterenol in patients with frequent premature ventricular contractions.

AIMS: Infrequent appearance and failed induction of premature ventricular contractions (PVCs) at catheter ablation make their localization difficult and are associated with a poor procedural outcome. This study aimed to assess the effect of preprocedural oral caffeine intake on induction of PVCs during catheter ablation. METHODS AND RESULTS: Seventy patients (age: 54 ± 14 years, 37 men) undergoing catheter ablation for monofocal PVCs were randomized to receive oral caffeine (5 mg/kg) or placebo. Before ablation, PVC counts for 5 min were performed at baseline and during isoproterenol infusion and the isoproterenol washout period. PVC count fluctuation was defined as the difference between the highest and lowest 5-min count among the three-time periods. The 5-min PVC counts during baseline and isoproterenol infusion were equivalent between the groups. However, those during the isoproterenol washout period and PVC count fluctuation were significantly higher in the caffeine group than the control group (73.1 ± 73.2 vs. 38.9 ± 28.9 beats/5 min, P = 0.012 and 69.3 ± 61.3 vs. 37.7 ± 30.9 beats/5 min, P = 0.008, respectively). The procedure and ablation times were significantly shorter in the caffeine group than the control group (105.0 ± 23.4 vs. 136.9 ± 43.2 min, P < 0.01 and 219.1 ± 104.7 vs. 283.5 ± 136.0 sec, P < 0.01, respectively). CONCLUSION: Oral caffeine intake amplified the effect of isoproterenol infusion on PVC induction during catheter ablation. The combined use of oral caffeine intake and isoproterenol infusion can be an option to increase intraprocedural PVCs.

Conversion to partial isthmus-dependent flutter during cavotricuspid isthmus ablation: The utility of Advisor HD grid in identifying local fragment electrograms.

Complete block creation by radiofrequency (RF) ablation at the cavotricuspid isthmus (CTI) is a highly successful procedure for the treatment of typical atrial flutter (AFL). Occasionally, a rare type of AFL, such as lower or upper loop reentry, or partial isthmus-dependent flutter, can coexist with typical right AFL. A 73-year-old man underwent CTI ablation for a clockwise CTI-dependent typical atrial flutter. During the ablation procedure, the morphology of the flutter wave changed in the surface electrocardiogram and endocardial atrial activation sequence, suggesting that the typical AFL had converted to another AFL (AFL2). High-density mapping using the HD grid catheter could not reveal the reentrant circuit of AFL2 but detected a critical conduction gap at the boundary between the inferior vena cava and CTI. There was also an impulse collision in the remaining CTI. The RF application at the gap terminated the AFL2 and completed the block line of the CTI. Based on these findings, AFL2 was comparable with partial isthmus-dependent flutter. The present case demonstrates the utility of high-density mapping with a HD grid for the identification of small amplitude high-frequency electrograms at critical sites of the arrhythmia. Learning objective: A rare type of atrial flutter (AFL) can coexist with typical AFL. In such cases, a high-density mapping is useful to identify the critical portion of the reentrant circuit. The Advisor HD grid multipolar catheter (Abbott, St Paul, MN, USA) is unique in that it allows bipolar recording perpendicular and parallel to the splines via 16 electrodes. In this case report, high density mapping using HD grid catheter identified small amplitude high-frequency electrograms at critical sites of the arrhythmia.