Spatial Relation Between Left Atrial Anatomical Contact Areas and Circular Activation in Persistent Atrial Fibrillation.

INTRODUCTION: Atrial low-voltage zones (LVZs) may be related to maintenance of atrial fibrillation (AF). The influence of left atrial (LA) contact areas (CoAs) on reentrant or rotor-like sources maintaining AF has not been investigated. METHODS AND RESULTS: Forty patients with persistent AF (PsAF) were analyzed. Three representative CoA regions in the LA (ascending aorta: anterior wall; descending aorta: left inferior pulmonary vein; and vertebrae: posterior wall) were visualized by enhanced CT. Using circular catheters, the LVZs (<0.5 mV) were assessed after restoration of SR, and local activation mapping and frequency domain analyses were performed after induction of AF. Circular activation during AF was visually defined as sites with ≥2 rotations by serial electrograms encompassing >80% of the mean AF cycle length. A pivot was defined as the core of the localized circular activation. Anterior (39/40 patients, 98%), left pulmonary vein antrum (27/40, 68%), and posterior (19/40, 48%) CoAs were identified, and 80% (68/85) of those sites were overlapped by or close (<3 mm) to LVZs. Thirty-six (90%) patients demonstrated circular activation (3.1±1.7 sites/patients) along with significantly higher organized dominant frequencies (6.3 ± 0.5 Hz, regularity-index: 0.26 [0.23-0.41]) within the LA, and the average electrogram amplitude of those pivots was 0.30 mV (0.18-0.52). Of those sites, 55% (66/120) were located at or close to CoA regions. Catheter ablation including of LVZs neighboring CoAs terminated AF in 9 (23%) patients. CONCLUSIONS: External anatomical structures contacting the LA may be related to unique conduction properties in diseased myocardium necessary for PsAF maintenance.

Pathological autopsy of a patient that underwent a successful ablation of an electrical storm from the left ventricular summit.

A 65-year-old man with non-ischemic cardiomyopathy, underwent an autopsy 2 months after the successful ablation of a sustained left ventricular (LV) summit ventricular tachycardia (VT). The patient died due to interstitial pneumonia from amiodarone use. The earliest activation sites of the VT were documented from both inside the anterior interventricular vein (AIV) and epicardial surface. The diameter of the AIV was 3-4 mm, and the radiofrequency (RF) lesion inside the AIV was a slight lesion due to high impedance with a high temperature. The lesion from the epicardial surface was also superficial and insufficient due to neighboring coronary arteries and the existence of epicardial fat. A successful application was performed from the LV endocardium, and diffuse myocardial fibrosis was observed in the mid-myocardium including inside the RF lesions. The actual relationship between the myocardial fibrosis and LV summit VT remains unclear, but this case showed the difficulty of achieving a successful ablation from the epicardial side, when the focus exists in the mid-myocardium around the LV summit.

Integration of intracardiac echocardiography and computed tomography during atrial fibrillation ablation: Combining ultrasound contours obtained from the right atrium and ventricular outflow tract.

BACKGROUND: We aimed to optimize the acquisition of the left atrial (LA) and pulmonary vein (PV) ultrasound contours for more accurate integration of intracardiac echocardiography (ICE) and computed tomography (CT) using the CARTO® 3 system during atrial fibrillation (AF) ablation. METHODS: Eighty-five AF patients underwent integration of ICE and CT using (1) the LA roof and posterior wall contours acquired from the right atrium (RA), (2) all LA/PV contours from the RA (Whole-RA-integration), (3) the LA roof/posterior wall contours from the RA and right ventricular outflow tract (RVOT) (Posterior-RA/RV-integration), and (4) all LA/PV contours from the RA and RVOT (Whole-RA/RV-integration). The integration accuracy was compared using the (1) surface registration error, (2) distances between the three-dimensional CT and eight specific sites on the anterior, posterior, superior, and inferior aspects of the right and left circumferential PV isolation lines, and (3) registration score: a score of 0 or 1 was assigned for whether or not each specific site was visually aligned with the CT, and summed for each method (0 best, 8 worst). RESULTS: Posterior-RA/RV-integration revealed a significantly lower surface registration error (1.30±0.15mm) than Whole-RA- and Whole-RA/RV-integration (p<0.001). The mean distances of the eight specific sites and the registration score for Posterior-RA/RV-integration (median 1.26mm and 2, respectively) were significantly smaller than those for the other integration approaches (p<0.001). CONCLUSIONS: Image integration with the LA roof and posterior wall contours acquired from the RA and RVOT may provide greater accuracy for catheter navigation with three-dimensional CT during AF ablation.

Investigation of the atrial conduction time measured by tissue Doppler imaging at the left atrial appendage and the actual electrical conduction time: consideration of left atrial remodeling in atrial fibrillation patients.

PURPOSE: The atrial conduction time measured by echocardiography using tissue Doppler imaging (TDI) has been reported as a predictive factor of left atrial (LA) remodeling. We investigated the P wave to LA appendage (LAA) conduction time defined by transthoracic echocardiography using TDI (P-LAA TDI), and directly compared the actual LA electrical conduction time determined by the electrophysiological data. Additionally, we confirmed the clinical utility of the P-LAA TDI by examining the relationship to the electroanatomical LA remodeling data. METHODS: Sixty-three AF patients (22 paroxysmal AF, 41 persistent AF) underwent ablation and electroanatomical LA mapping. The P-LAA TDI was measured after the ablation and was compared with the electrophysiological data during sinus rhythm, including the actual electrical conduction time. RESULTS: A strong linear correlation (r = 0.776, p < 0.001, y = 1.28x + 49) was observed between the P-LAA TDI (161 ± 24 ms) and electrophysiological P-LAA time (87 ± 15 ms). The P-LAA TDI was also strongly correlated with the LA volume (173 ± 52 ml, r = 0.632, p < 0.001) and LA conduction velocity index (1.07 ± 0.19 mm/ms, r = -0.735, p < 0.001), but less to the focal anterior-LVA region surface area (2.2 [0.4-5.0] cm2, r = 0.380, p = 0.002). Additionally, a stepwise multiple linear regression demonstrated that both the LA volume and LA conduction velocity index were strongly associated with the value of the P-LAA TDI (p < 0.001). CONCLUSIONS: The P-LAA TDI was useful for estimating the actual electrophysiological conduction time and represented both electrical and anatomical LA remodeling.

Temporal sinus node modification by high-dose continuous intravenous administration of landiolol in a patient with persistent inappropriate sinus tachycardia.

A 20-year-old woman underwent an electrophysiological study for drug-resistant persistent inappropriate sinus tachycardia (IST). Use of a high-dose continuous intravenous administration of landiolol, a short-acting beta-adrenoreceptor blocker, made the patient׳s heart rate suddenly drop with a slight change in the P-wave morphology. Three-dimensional right atrial (RA) activation mapping revealed that the earliest activation site moved 8 mm to a lower anterior site around the high lateral RA. Radiofrequency energy applied to the earliest activation site during tachycardia was successful. A temporal sinus node modification with landiolol administration was useful for mapping and for safe catheter ablation of IST.

Impact of catheter tip-tissue contact on three-dimensional left atrial geometries: Relationship between the external structures and anatomic distortion of 3D fast anatomical mapping and high contact force guided images.

BACKGROUND: A high catheter tip-tissue contact force (CF) with the myocardium may cause 3-dimensional (3D) map distortion, however, the influence of external structures surrounding the left atrium (LA) on that distortion remains unknown. This study characterized the impact of high CF mapping on the local LA geometry distortion. METHODS: Thirty AF patients underwent 3D-ultrasound merged with CT images (3D-Merge-CT). The LA area in contact with external structures was identified by enhanced CT. Fast-electroanatomical-mapping (FAM) geometries were created by two methods, point-by-point mapping with high (>10g) CFs (high-CF guided-FAM), followed by that with multielectrode-mapping catheters (conventional-FAM). The resulting geometries were compared with the 3D-Merge-CT images. RESULTS: Three representative anatomical contact areas (ascending aorta-vs.-anterior wall, descending aorta-vs.-left pulmonary vein [PV], and vertebrae-vs.-posterior wall) were identified. The PV antrum distorted distance on the 3D-Merge-CT was significantly longer for high-CF guided-FAMs than conventional-FAMs (1.7[0-3.6] vs. 0[0-1.8]mm, P<0.0001). In high-CF maps, the distorted distance significantly differed between regions with and without contact areas in both the PV antrum (0[0-0.17] vs. 1.7[0-3.9]mm, P=0.0201) and LA body region (0[0-1.5] vs. 1.7[0.7-2.2]mm, P<0.005). The catheter tip-tissue CF did not correlate with the distorted distance (r=0.08, P=0.46), and a multivariate analysis revealed that the absence of anatomical contact areas was strongly associated with significant local distortion, independent of the CF. CONCLUSIONS: High-CF guided mapping yields greater 3D-image anatomical distortion than conventional-FAM methods. That distortion was attenuated by regions with anatomical contact areas, suggesting that regional anatomic distortion is involved in the existence of external structures surrounding the LA.