Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias.

INTRODUCTION: Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. METHODS: This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. RESULTS: Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. CONCLUSION: A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Impact of catheter ablation and subsequent recurrence of atrial fibrillation on glucose status in patients undergoing continuous glucose monitoring.

Although glucose metabolism and atrial fibrillation (AF) have complex interrelationships, the impact of catheter ablation of AF on glucose status has not been well evaluated. Continuous glucose monitoring (CGM) with a FreeStyle Libre Pro (Abbott) was performed for 48 h pre-procedure, during the procedure, and for 72 h post-procedure in 58 non-diabetes mellitus (DM) patients with symptomatic AF and 20 patients with supraventricular or ventricular arrhythmias as a control group. All ablation procedures including pulmonary vein isolation were performed successfully. Glucose levels during procedures consistently increased in the AF and control groups (83.1 ± 16.1 to 110.0 ± 20.5 mg/dL and 83.3 ± 14.7 to 98.6 ± 16.3 mg/dL, respectively, P < 0.001 for both), and Δ glucose levels (max minus min/procedure) were greater in the AF group than control group (P < 0.001). There was a trend toward higher mean glucose levels at 72 h after the procedures compared with those before the procedures in both the AF and control groups (from 103.4 ± 15.6 to 106.1 ± 13.0 mg/dL, P = 0.063 and from 100.2 ± 17.1 to 102.9 ± 16.9 mg/dL, P = 0.052). An acute increase in glucose level at the time of early AF recurrence (N = 9, 15.5%) could be detected by simultaneous CGM and ECG monitoring (89.7 ± 18.0 to 108.3 ± 30.5 mg/dL, P = 0.001). In conclusion, although AF ablation caused a statistically significant increase in the glucose levels during the procedures, it did not result in a pathologically significant change after ablation in non-DM patients. Simultaneous post-procedure CGM and ECG monitoring alerted us to possible acute increases in glucose levels at the onset of AF recurrence.

An Epicardial Connection With a Unidirectional Conduction Property From the Left Atrium to Pulmonary Vein.

The presence of an epicardial connection between the left-sided pulmonary vein and left atrium was suggested during catheter ablation of atrial fibrillation because of sustainable unidirectional entrance conduction after complete endocardial ablation, centrifugal breakout deep inside the pulmonary vein, and immediate elimination of the conduction by point ablation. (Level of Difficulty: Advanced.).

Epicardial Connections as Intra-Atrial Conduction Routes in a Patient With Advanced Atrial Remodeling.

In a patient with long-standing persistent atrial fibrillation, elimination of an epicardial connection between the right-sided pulmonary venous carina and the right atrium during catheter ablation resulted in intra-atrial conduction injuries in the presence of advanced atrial remodeling. (Level of Difficulty: Advanced.).

Features Suggesting Preferential Conduction in Pulmonary Artery Ventricular Arrhythmia for Identification of Successful Ablation Sites.

Radiofrequency catheter ablation (RFCA) for pulmonary artery ventricular arrhythmia (PAVA) can be difficult because of the occasional existence of PAVA with preferential conduction.This study described the characteristics of PAVA that demonstrate preferential conduction.We analyzed electrocardiographic and electrophysiological data from 8 patients found to have PAVAs with preferential conduction out of 183 patients (4.4%) with right ventricular outflow tract (RVOT) arrhythmias who underwent RFCA at our hospitals. The PAVA with preferential conduction were classified into two types. In type 1 PAVA, successful ablation sites (success-sites) exhibited discrete prepotentials with an isoelectric line, in which the activation time (AT) was ≥ 50 milliseconds. In type 2 PAVA, excellent pace mapping was achieved at two sites separated by ≥ 20 mm: one in the RVOT free wall and the other at the success-site in the pulmonary artery. Type 1 and 2 PAVA features were considered signs of a short and long preferential conduction pathway, respectively.There were four patients each with type 1 and 2 PAVA. Type 1 PAVA was distinguished by the isoelectric line at success-sites with the mean AT of 78 ± 25.1 milliseconds. In type 2 PAVAs, although the AT at RVOT sites was very short (18.5 ± 10.1 milliseconds), the AT at success-sites was longer than that at the RVOT by 42.3 ± 36.2 milliseconds. Type 2 PAVAs displayed distinct electrocardiogram (ECG) features (R wave in lead I, RR' in inferior leads, and transitional zone in V4) not found in typical PAVA ECGs.PAVA with preferential conduction can manifest in distinct ways on the ECG and intracardiac mapping. Knowledge of these features may facilitate successful RFCA of such PAVA cases.

Predictors of Recurrence after Catheter Ablation of Paroxysmal Atrial Fibrillation in Different Follow-Up Periods.

Background and objectives: Pulmonary vein (PV) reconnection is a major reason for recurrence after catheter ablation of paroxysmal atrial fibrillation (PAF). However, the timing of the recurrence varies between patients, and recurrence >1 year after ablation is not uncommon. We sought to elucidate the characteristics of atrial fibrillation (AF) that recurred in different follow-up periods. Materials and Methods: Study subjects comprised 151 consecutive patients undergoing initial catheter ablation of PAF. Left atrial volume index (LAVi) and atrial/brain natriuretic peptide (ANP/BNP) levels were systematically measured annually over 3 years until AF recurred. Results: Study subjects were classified into four groups: non-recurrence group (n = 84), and short-term- (within 1 year) (n = 30), mid-term- (1-3 years) (n = 26), and long-term-recurrence group (>3 years) (n = 11). The short-term-recurrence group was characterized by a higher prevalence of diabetes mellitus (hazard ratio 2.639 (95% confidence interval, 1.174-5.932), p = 0.019 by the Cox method), frequent AF episodes (≥1/week) before ablation (4.038 (1.545-10.557), p = 0.004), and higher BNP level at baseline (per 10 pg/mL) (1.054 (1.029-1.081), p < 0.0001). The mid-term-recurrence group was associated with higher BNP level (1.163 (1.070-1.265), p = 0.0004), larger LAVi (mL/m2) (1.033 (1.007-1.060), p = 0.013), and longer AF cycle length at baseline (per 10 ms) (1.194 (1.058-1.348), p = 0.004). In the long-term-recurrence group, the ANP and BNP levels were low throughout follow-up, as with those in the non-recurrence group, and AF cycle length was shorter (0.694 (0.522-0.924), p = 0.012) than those in the other recurrence groups. Conclusions: Distinct characteristics of AF were found according to the time to first recurrence after PAF ablation. The presence of secondary factors beyond PV reconnections could be considered as mechanisms for the recurrence of PAF in each follow-up period.

Perfect pace-mapping with different latencies from adjacent sites in bilateral outflow tract leading to successful sequential unipolar ablation.

A 77-year-old man with frequent monomorphic ventricular premature contractions (VPCs) was referred for catheter ablation. Detailed mapping just above the pulmonary valve (PV) revealed tiny fragmented potentials earlier than the VPC onset. Perfect pace-mapping was obtained using high voltage pacing just above the PV and the left aortic sinus of Valsalva, whose stimulus-to-VPC latencies differed by 20 ms. While the ablation at the pulmonary valve could not completely eliminate the VPCs, unipolar sequential ablation on both sides of the outflow tracts led to their successful abolition that was guided by perfect pace-mapping.

Noninvasive Mapping of Premature Ventricular Contractions by Merging Magnetocardiography and Computed Tomography.

OBJECTIVES: This study aimed to develop a novel premature ventricular contraction (PVC) mapping method to predict PVC origins in whole ventricles by merging a magnetocardiography (MCG) image with a cardiac computed tomography (CT) image. BACKGROUND: MCG can noninvasively discriminate PVCs originating from the aortic sinus cusp from those originating from the right ventricular outflow tract. METHODS: This study was composed of 22 candidates referred for catheter ablation of idiopathic PVCs. MCG and CT were performed the same day before ablation. Estimated origins by MCG-CT imaging using the recursive null steering spatial filter algorithm were compared with origins determined by electroanatomic mapping (CARTO, Biosense Webster, Inc., Diamond Bar, California) during the ablation procedure. Radiopaque acrylic markers for the CT scan and coil markers generating a weak magnetic field during MCG measurements were used as reference markers to merge the 2 images 3-dimensionally. RESULTS: PVC origins were determined by endocardial and epicardial mapping and ablation results in 18 (86%) patients (right ventricular outflow tract in 10 patients, aortic sinus cusp in 2 patients, interventricular septum in 1 patient, near His bundle in 1 patient, right ventricular free wall in 1 patient, and left ventricular free wall in 3 patients). Estimated origins by MCG-CT imaging matched the origins determined during the procedure in 94% (17 of 18) of patients, whereas the electrocardiography algorithms were accurate in only 56% (10 of 18). Discrimination of an epicardium versus an endocardium or right- versus left-sided septum was successful in 3 of 4 patients (75%). CONCLUSIONS: The diagnostic accuracy of noninvasive MCG-CT mapping was high enough to allow clinical use to predict the site of PVC origins in the whole ventricles.

Initial Result of Antrum Pulmonary Vein Isolation Using the Radiofrequency Hot-Balloon Catheter With Single-Shot Technique.

OBJECTIVES: This study sought to determine the feasibility of a novel simplified ablation protocol targeting only the pulmonary vein antrum using the radiofrequency hot-balloon catheter in patients with paroxysmal atrial fibrillation. BACKGROUND: Radiofrequency hot-balloon (RHB) catheter has been recently introduced into clinical practice for pulmonary vein isolation (PVI). The authors hypothesized that a novel simplified ablation protocol targeting only the PV antrum with energy application for a longer time (single-shot technique) could be an alternative approach to achieve PVI, while avoiding unnecessary energy application at the PV ostium. METHODS: A total of 61 consecutive paroxysmal atrial fibrillation patients (age 64.1 ± 10.9 years, 48 male) who underwent antrum RHB-PVI were enrolled. Energy applications were performed following the pre-specified protocol only targeting the PV antrum. If the PVI was not achieved after 2 energy applications using the RHB, a touch-up ablation was performed. RESULTS: Of 241 PV, including 3 left common PV, 194 (80%) were isolated exclusively using the RHB. The target PVI average per group of 15 consecutive procedures improved from 75% (initial 15) to 89% (last 16) of patients. The injected volume was greatest in the right superior PV (13.1 ± 2.0 ml) and the smallest in the left inferior PV (10.8 ± 1.1 ml), and 23 PV (9.5%) required over 15 ml (estimated balloon diameter of 30 mm). Periprocedural complications were noted in 3 patients (4.9%), but phrenic nerve injury was not observed. Sinus rhythm maintenance at 12-month follow-up was achieved in 57 patients (93%). CONCLUSIONS: A novel simplified antrum RHB-PVI appears to be a feasible technique for the treatment of paroxysmal atrial fibrillation.

Epicardial connection between the right-sided pulmonary venous carina and the right atrium in patients with atrial fibrillation: A possible mechanism for preclusion of pulmonary vein isolation without carina ablation.

BACKGROUND: Ablation of the pulmonary venous carina is occasionally required for pulmonary vein isolation (PVI) despite its nonessential role in ipsilateral PVI from the anatomical (endocardial) viewpoint. Although the Bachmann bundle (BB) is a common and main interatrial band, local variations in small tongues of muscular fibers were frequently found in autopsy studies. OBJECTIVE: We sought to clarify the effect of the electrical conduction pattern from the right atrium (RA) to the left atrium (LA) during sinus rhythm on the necessity of performing right-sided pulmonary venous carina ablation to achieve PVI. METHODS: Study subjects comprised 37 consecutive patients undergoing initial catheter ablation of lone atrial fibrillation. During sinus rhythm, RA and LA activation maps were acquired using an electroanatomical mapping system. LA breakthroughs were classified into 3 sites: BB, fossa ovalis (FO), and right-sided pulmonary venous carina. Patients were divided into the carina-ABL (ablation) or non-carina-ABL group on the basis of the necessity of pulmonary venous carina ablation to achieve PVI. RESULTS: Patients were classified in the non-carina-ABL group (n = 26 [70%]) and carina-ABL group (n = 8 [22%]) after excluding 3 patients (8%) because of their complex ablation lesion sets. Breakthrough occurred in the BB (n = 21 patients [62%]), FO (n = 7 [21%]), carina (n = 1 [3%]), carina and BB (n = 3 [9%]), and carina and FO (n = 2 [6%]). Carina breakthrough occurred in 6 patients (75%) in the carina-ABL group but in no patients in the non-carina-ABL group (P < .0001). CONCLUSION: PVI was not achievable without carina ablation in one-fifth of patients, probably because of epicardial connections present between the right-sided pulmonary venous carina and the RA.

Underrecognized entity of the transient rise in the atrial capture threshold early after dual-chamber pacemaker implantation.

BACKGROUND: Steroid-eluting pacemaker leads suppress acute rises in pacing threshold by preventing inflammatory processes. However, we occasionally encounter not persistent but transient rise in the atrial capture threshold (TRACT) early after pacemaker implantation. We believe that this phenomenon is underrecognized in clinical practice and may potentially lead to unnecessary reintervention. We aimed to clarify the prevalence, predictors, and possible mechanisms of TRACT. METHODS AND RESULTS: We reviewed clinical records from 239 consecutive patients who underwent dual-chamber pacemaker implantation for sick sinus syndrome (SSS) (N = 102) or atrioventricular block (AVB) (N = 137). Atrial capture threshold was measured at implantation and 7 days, 2 months, and 8 months postimplantation. TRACT was defined as a rise in the threshold at day 7 to ≥twice that at implantation, with an absolute value ≥1.0 V/0.4 ms, and full recovery by 8 months into follow-up. TRACT was observed in 15 patients (6%), of whom13 (87%) suffered from SSS but not AVB. Patients with TRACT had greater body mass index (BMI) (25 ± 5 kg/m2 vs 23 ± 4 kg/m2 , P = 0.01), larger left atrium (42 ± 5 mm vs 38 ± 7 mm, P = 0.03), and were more likely to suffer from paroxysmal atrial fibrillation (60% vs 31%, P = 0.02) than those without TRACT. In multivariable logistic regression analysis, BMI and SSS were the independent predictors of TRACT (odds ratio [OR], 1.172; 95% confidence interval [CI], 1.019-1.349; P = 0.03 and OR, 11.53; 95% CI, 2.010-66.21; P = 0.006, respectively). CONCLUSIONS: The distinct phenomenon of TRACT was not rare in clinical practice early after dual-chamber pacemaker implantation, and its occurrence was strongly associated with SSS.

Electrophysiological relation between the superior vena cava and right superior pulmonary vein in patients with paroxysmal atrial fibrillation.

INTRODUCTION: The superior vena cava (SVC) is a main source of nonpulmonary vein (PV) ectopies initiating atrial fibrillation (AF). Empiric SVC isolation may improve rhythm outcomes after catheter ablation of AF. Because the SVC passes immediately adjacent to the right superior PV (RSPV), an electrophysiological relation could be present between the two structures. The present study aimed to estimate the interrelation between the SVC and RSPV by evaluating arrhythmogenic activities observed during catheter ablation of AF. METHODS AND RESULTS: Study subjects comprised 121 consecutive patients referred for catheter ablation of paroxysmal AF. Isoproterenol infusion was used to induce ectopies and AF. Patients were divided into two groups depending on the presence of arrhythmogenic SVC: arrhythmogenic-SVC (A-SVC) and nonarrhythmogenic SVC (Non-A-SVC) groups. The prevalence of females was higher and body surface area was smaller in the A-SVC group (N = 22) than Non-A-SVC group (N = 99). Arrhythmogenic activities were observed in 60 (49%) RSPVs, 24 (20%) right inferior PVs, 72 (59%) left superior PVs, and 31 (25%) left inferior PVs. Arrhythmogenic RSPVs were more prevalent in the A-SVC group than Non-A-SVC group (86% vs. 41%, P = 0.0001), whereas these prevalences in the other three PVs were not different between groups (P >0.3). In multivariable analysis, arrhythmogenic RSPV was the only independent predictor of arrhythmogenicity of the SVC (OR, 8.53; 95% CI 2.31-31.46; P = 0.001). CONCLUSIONS: An electrophysiological interrelation may be present between the SVC and RSPV in patients with paroxysmal AF. Semiempiric SVC isolation limited to patients with an arrhythmogenic RSPV may be a more efficient treatment strategy.

Comparison of Pulmonary Venous and Left Atrial Remodeling in Patients With Atrial Fibrillation With Hypertrophic Cardiomyopathy Versus With Hypertensive Heart Disease.

Left ventricular diastolic dysfunction in hypertrophic cardiomyopathy (HC) increases susceptibility to atrial fibrillation. Although phenotypical characteristics of the hypertrophied left ventricle are clear, left atrial (LA) and pulmonary venous (PV) remodeling has rarely been investigated. This study aimed to identify differences in LA and PV remodeling between HC and hypertensive heart disease (HHD) using 3-dimensional computed tomography. Included were 33 consecutive patients with HC, 25 with HHD, and 29 without any co-morbidities who were referred for catheter ablation of atrial fibrillation. Pre-ablation plasma atrial and brain natriuretic peptide levels, post-ablation troponin T level, and LA pressure were measured, and LA and PV diameters were determined 3 dimensionally. LA transverse diameter in the control group was smaller than that in the HHD or HC group (55 ± 6 vs 63 ± 9 vs 65 ± 12 mm, p = 0.0003). PV diameter in all 4 PVs was greatest in the HC group and second greatest in the HHD group (21.0 ± 3.1 vs 23.8 ± 2.8 vs 26.8 ± 4.1 mm, p <0.0001 for left superior PV). Differences in PV size between the HHD and HC groups were enhanced by indexing to the body surface area (12.4 ± 1.9 vs 13.1 ± 1.4 vs 16.1 ± 3.3 mm/m2, p <0.0001). The PV/LA diameter ratio was greater in the HC than in the other groups (0.38 ± 0.06 vs 0.38 ± 0.05 vs 0.42 ± 0.07, p = 0.01). Atrial natriuretic peptide, brain natriuretic peptide, troponin T levels, and LA pressure were highest in the HC group (all p <0.05). In conclusion, the stiff LA caused from atrial hypertrophy may account for higher levels of biomarkers, higher LA pressure, and PV-dominant remodeling in HC.

[Acquired Left Ventricular-right Atrial Communication due to Infective Endocarditis;Report of a Case].

A 77-year-old woman presented with a 3-week history of low grade fever, appetite loss and dizziness. An electrocardiogram showed complete heart block. Echocardiography demonstrated severe aortic valve stenosis and a mass of probable vegetation 2 cm in diameter on the atrioventricular septum in the right atrium (RA), but no obvious intra-cardiac fistula. There was no growth of organism in blood cul tures. In the 4th week after admission, a harsh and continuous cardiac murmur was detected for the 1st time. Portable echocardiography revealed disappearance of the mass in the RA, and showed an intra-cardiac shunt from the left ventricle( LV) to RA. The shunt was closed by autologous pericardial patch form LV side and directly with mattress suture form RA side during the emergency operation. The aortic valve was replaced with bio-prosthetic valve (SJM Trifecta 19 mm). No organism was detected in the excised tissue, but antibiotics were continued for 2 months until a permanent pacemaker was inserted.