Rikitake Kogawa

Relation Between Left Atrial Wall Thickness in Patients with Atrial Fibrillation and Intracardiac Electrogram Characteristics and ATP-Provoked Dormant Pulmonary Vein Conduction

Atrial remodeling plays a key role in development of the substrate for atrial fibrillation (AF). Whether the wall thicknesses of the left atrium (LA) and pulmonary vein (PV)–LA junction affect remodeling and AF ablation is unknown. We investigated the relationship between wall thicknesses, electrogram characteristics, and adenosine triphosphate (ATP)‐provoked dormant PV conduction as they pertain to AF.

Relations between contact force, bipolar voltage amplitude, and mapping point distance from the left atrial surfaces of 3D ultrasound- and merged 3D CT-derived images: Implication for atrial fibrillation mapping and ablation.

BACKGROUND Catheter tip-derived contact force (CF) and 3-dimensional (3D) maps are key to mapping and ablation of atrial fibrillation. OBJECTIVE This study sought to determine the relation between CF and 3D map surfaces. METHODS We conducted a validation study of Carto-based 3D ultrasound (3D-US) and 3D-US merged with computed tomography (3D-Merge-CT) left atrium/pulmonary vein images. Under fluoroscopic guidance, 1361 mapping points (20 patients) with CFs and electrogram information were randomly acquired around the PVs. RESULTS CF correlated weakly with the distance of mapping points from the 3D-Merge-CT (r = 0.27; P < .001) and 3D-US (r = 0.22; P < .001) surfaces but not with bipolar voltage (r = -0.01; P = .2400). Low CF (0-4 g) yielded points close to the 3D-US surface; moderate (5-9 g) and high CFs (10-20 g) generated points beyond the surface (0.1 ± 3.9, 1.4 ± 3.4, and 2.3 ± 3.4 mm; P < .05 for each). Low, moderate, and high CFs yielded points below, close to, and beyond the 3D-Merge-CT surface (-1.2 ± 3.7, 0.4 ± 3.0, and 1.0 ± 2.9 mm; P < .05 for each). CONCLUSION Poor correlation between CF and the distance of mapping points from the 3D map surfaces and electrogram information shows the limitation of 3D mapping and electrogram information for predicting good contact. In addition, mapping seems to require far less CF than ablation requires.

Epicardial adipose tissue-based defragmentation approach to persistent atrial fibrillation: Its impact on complex fractionated electrograms and ablation outcome

BACKGROUND Increased epicardial adipose tissue (EAT) volume is associated with atrial fibrillation (AF). However, the efficacy of EAT-based left atrial (LA) ablation for persistent AF (PsAF) is unclear. OBJECTIVE The purpose of this study was to assess whether EAT-based LA ablation is effective for PsAF. METHODS In 60 PsAF patients (group I), 3-dimensional reconstructed computed tomography images depicting EAT were merged with NavX-based dominant-frequency (DF) and complex fractionated electrogram (CFE) maps obtained during AF. Pulmonary vein antrum isolation (PVAI) was followed by map-guided EAT-based ablation. Results were compared to those in a historical control group (group II, case-matched patients who underwent generalized stepwise ablation including linear plus CFE-targeted ablation). RESULTS In 70% (n = 42) of group I patients, the LA-EAT was located at the pulmonary vein antra; anterior and inferior surfaces, roof, septum, and mitral annulus; and left atrial appendage. EAT was at or near (<3 mm) 71% (390/550) of high-DF (> -8 Hz) sites. In 41 patients with persistent AF despite EAT-targeted ablation, CFE burden decreased significantly (from 96% to 13%, P < .0001), and DF decreased within the coronary sinus (6.9 ± 0.7 Hz vs 5.9 ± 0.7 Hz, P < .0001). Radiofrequency energy duration was significantly less in group I than in group II (25 ± 6 minutes vs 31 ± 12 minutes, P < .05). During 16-month follow-up, freedom from AF on antiarrhythmic drugs was 78% vs 60% (P < .05). CONCLUSION PVAI plus EAT-based ablation efficiently eliminates high-frequency sources and yields relatively high success. EAT-based LA ablation is a simple, clinically feasible PsAF ablation strategy.

Spatial and temporal variability of the complex fractionated atrial electrogram activity and dominant frequency in human atrial fibrillation

The presence of complex fractionated atrial electrograms (CFAEs) and high dominant frequencies (DFs) during atrial fibrillation (AF) have been demonstrated to be related to AF maintenance. Therefore, sequential mapping of CFAEs and DFs have been used for target sites of AF ablation. However, such mapping strategies are valid only if the CFAEs and DFs are spatiotemporally stable during the mapping procedure. We obtained spatially stable multi‐electrode recordings to assess the spatiotemporal stability of CFAEs and DFs.

Effect of cryoballoon inflation at the right superior pulmonary vein orifice on phrenic nerve location

BACKGROUND Cryoballoon catheter ablation was developed to simplify ablation for atrial fibrillation (AF). Initial enthusiasm for its widespread use has been dampened by phrenic nerve (PN) injury (PNI). OBJECTIVE The purpose of this study was to assess the effect of cryoballoon inflation at the right superior pulmonary vein (RSPV) orifice on PN location and to elucidate the potential mechanism of PNI. METHODS Twenty patients with paroxysmal atrial fibrillation underwent ablation performed with a second-generation 28-mm cryoballoon catheter. Before ablation, the pacing-determined PN course was delineated along the right atrium. PN location and its relation to the RSPV as well as RSPV surface distortions after balloon inflation were established with a NavX mapping system. RESULTS During RSPV ablation, the inflated balloon surface extended anteriorly 6.3 ± 1.8 mm outside the RSPV. This narrowed the distance between the PN capture points in the RSPV vs PN location from 11.4 ± 5.0 mm to 7.5 ± 5.0 mm (P = .0002) and increased the PN capture area from 1.9 ± 1.3 cm(2) to 3.2 ± 1.8 cm(2) (P = .0004). Furthermore, the PN capture points shifted toward the orifice within the RSPV and after balloon inflation were located significantly closer to the orifice in the 3 patients with transient PNI than in those without PNI. CONCLUSION Cryoballoon inflation at the RSPV orifice alters PV/left atrial surface geometry, reducing the distance between the energy delivery source and the PN and increasing PN area, possibly explaining the mechanism of PNI. PN pacing within the RSPV after balloon inflation may be useful for preventing PNI.

Changes over time in echocardiographic variables and atrial electromechanical intervals after ablation for atrial fibrillation

Acute and mid‐term effects of ablation for atrial fibrillation (AF) on left atrial (LA) and left ventricular (LV) function and the atrial electromechanical interval are controversial.

Mechanistic Insights Into Durable Pulmonary Vein Isolation Achieved by Second-Generation Cryoballoon Ablation

Background The mechanism explaining the efficacy of cryoballoon ablation (CBA) for atrial fibrillation has not been clarified. Methods and Results We compared lesion characteristics between patients in whom pulmonary vein isolation (PVI) was performed by CBA (n=56) and those by contact force (CF)-based RF ablation (n=56). We evaluated the 3-dimensional PV morphology before and after cryoballoon inflation. After PVI, a 3D left atrial voltage map was created. Pacing (10 mA and 2 ms) was performed within the low voltage area from the ablation line, and electrically unexcitable ablated tissue was identified. ATP-provoked dormant conduction after PVI occurred in 9 of the 224 (4%) PVs in the CBA group and in 13 of the 224 (6%) PVs in the CF group (P=0.3935). The inflated balloon stretched the PV from the original PV ostial surface by 7.1±3.5 mm, but at sites with (vs, sites without) residual PV potential/dormant conduction, the extent of the PV distension was reduced (4.0±4.0 mm vs. 7.2±3.4 mm, P<0.0001). The unexcitable ablated tissue around the PVs was significantly wider in CB patients than in CF patients (16.7±5.1 mm vs. 5.3±2.3 mm, P<0.0001). Conclusions Use of the cryoballoon significantly distends the PV. Without this extensive distention, PVI may not be successful. CBA seems to yield wide unexcitable ablation zones. These factors seem to explain the durability of CBA lesions.

Frequency analysis of atrial fibrillation from the specific ECG leads V7-V9: A lower DF in lead V9 is a marker of potential atrial remodeling

INTRODUCTION High dominant frequency (DF) sites during atrial fibrillation (AF) play an important role in the perpetuation of AF. We investigated the relationship between the DFs from intracardiac electrograms (iEGM) and the surface electrocardiogram (ECG) during AF, and the relationship between the surface ECG DF and atrial remodeling. METHODS In 48 patients (57±11 years, 47 males, 20 paroxysmal), the V1-6 precordial leads and specific V7-9 ECG leads were recorded for 8s for an off-line analysis before AF ablation. The QRS-T complex was canceled by a template subtraction algorithm using the CEPAS™ system (Cuoretech Pty Ltd, Sydney, Australia). The iEGM DF maps, reconstructed using the Ensite NavX (St. Jude Medical, Inc., St. Paul, MN, USA) system, were simultaneously created for the right atrium and left atrium (LA) during AF. RESULTS The DF in leads V8 and V9 correlated well with the DF in the LA floor (R=0.55, p<0.01; R=0.68, p<0.01, respectively), and that in V1 with the right inferior pulmonary vein (R=0.45, p=0.01). Persistent AF patients had a significantly lower DF in lead V9 (5.7±1.0Hz vs. 6.7±1.5Hz, p=0.02) than paroxysmal AF patients. CONCLUSIONS A frequency analysis from lead V9 reflects the LA electrical activity.

Analysis of the spatial and transmural dispersion of repolarization and late potentials derived using signal-averaged vector-projected 187-channel high-resolution electrocardiogram in patients with early repolarization pattern

Electrophysiological characteristics of early repolarization syndrome (ERS), i.e., the spatial and transmural dispersion of ventricular repolarization and ventricular late potentials can be evaluated using a signal‐averaged vector‐projected 187‐channel high‐resolution electrocardiogram (187‐ch SAVP‐ECG). We investigated these characteristics as markers of ventricular fibrillation and sudden cardiac arrest in patients presenting with an ER pattern.

Termination of atrial fibrillation by ablation of high-dominant frequency sites adjacent to epicardial adipose tissue

We report an interesting case in which atrial fibrillation (AF) was terminated during ablation of high‐dominant frequency (DF) sites covered with epicardial adipose tissue (EAT). High‐DF sites are known to be related to the center of focal‐firing rotors or local reentry circuits. Therefore, this phenomenon suggests that EAT may be related to the development of dominant rotors maintaining AF.