Left Atrial Roof Research Articles

Important factors in left atrial posterior wall isolation using 28-mm cryoballoon ablation for persistent atrial fibrillation-Block line or isolation area?

Left atrial (LA) roof ablation using the cryoballoon technique, combined with pulmonary vein isolation (PVI), has been reported to be beneficial for ablation therapy in patients with persistent atrial fibrillation (AF). Left posterior wall ablation also results in improved patient outcomes. However, the contribution of these techniques to the success of cryoballoon ablation (CBA) treatment of AF is not known. The present study examined the influence of the roofline block and isolation area on outcomes after CBA. We enrolled 78 patients with persistent AF. LA roof ablation was performed using a 28-mm cryoballoon with a single freezing of 3 minutes at each region (median number of freezes: 4) after PVI. After CBA, bipolar voltage amplitude mapping was performed during sinus rhythm using the NavX mapping system. Patients were divided into two subgroups according to the voltage and activation map: the roof-conduction (n = 46) and roofline-block groups (n = 32). Atrial tachyarrhythmia recurred in 20 patients of the conduction group and 4 patients of the roofline-block group. The rate of 12-month freedom from tachyarrhythmia after a single ablation procedure was 78% (95% confidence interval [CI], 60%-89%) in the roofline-block group and 45% (95% CI, 30%-60%) in the conduction group (P = .048). Cox proportional hazard analysis revealed that the isolated area was not a significant predictor of recurrence (hazard ratio, 0.94; 95% CI, 0.86-1.02; P = .15). Creating a complete roofline block is the major factor predicting the maintenance of sinus rhythm in patients with persistent AF.

Risk Factors and Predictors of Cardiac Erosion Discovered from 12 Japanese Patients Who Developed Erosion After Atrial Septal Defect Closure Using Amplatzer Septal Occluder.

Cardiac erosion is a rare serious complication following Amplatzer septal occluder (ASO) placement for atrial septal defect. Although multiple risk factors have been found, a useful predictor to prevent it has not been established yet. In 12 patients who developed erosion between 2005 and 2016 in Japan, we retrospectively observed patients' characteristics and transesophageal echocardiography findings immediately before and after ASO placement and at erosion onset. We compared risk factors of erosion, including absent aortic rim, device size/body weight ratio, device shape, or Valsalva sinus wall deformation pressed by either disk-edge, the maximum depth of which from the standard curve of the Valsalva wall was defined as Dent, between the 12 patients and 95 patients with Valsalva sinus wall deformation immediately after placement who did not develop erosion for 5 ± 3years. Of the 12 patients, nine developed pericardial effusion with eight cardiac tamponade and three aorta-atrium fistula; all were surgically rescued. Surgical findings revealed that erosion in all patients occurred at the right and/or left atrial roof beside the Valsalva in the non-coronary cusp on which the disk-edge seemed to be pressing. The mean Dent immediately after the placement in patients with erosion was significantly deeper than without (2.48 ± 0.32 vs. 1.28 ± 0.38; p < 0.001). There were no differences in the other risk factors between the two groups. Dent is believed to be a useful indicator of erosion development after ASO placement. If Dent is > 2.0mm, it is desirable to change the size or to replace the device.

Large left atrial cavernous hemangioma, a case report

BackgroundCardiac cavernous hemangiomas are extremely rare and usually difficult to be diagnosed for being asymptomatic.Case presentationAn asymptomatic 56-year-old woman was hospitalized due to a heart mass found by chest computed tomography (CT) during her annual physical examination. Coronary computed tomography angiography (CTA) disclosed a tumorous lesion, located in the left atrial roof and extended to the posterior wall of the aortic root and surrounding the left main coronary artery. However, there was no communicating branches between the hemangioma and coronary artery and no coronary artery stenosis. The tumor was excised with low-frequency electrocautery under cardiopulmonary bypass. The histopathological examination indicated the mass a cavernous hemangioma. The patient was discharged with an uneventful recovery.ConclusionsHere we presented a rare case of successfully excision of a cavernous hemangioma involving the left atrial roof and left coronary artery. We advocate adequate exposure and complete surgical excision with low-frequency electrocautery to avoid remnants and excessive resection.

Left atrial roof ablation in patients with persistent atrial fibrillation using the second-generation cryoballoon: benefit or wasted time?

It is unknown whether left atrial (LA) roof ablation combined with pulmonary vein isolation (PVI) using a second-generation cryoballoon provides additional benefit beyond that of PVI alone in patients with persistent atrial fibrillation (AF). The aim of this study was to compare arrhythmia recurrence rates after PVI alone versus PVI plus LA roof ablation. In this observational study, we analyzed 399 symptomatic patients with persistent AF treated with cryoballoon ablation. After univariate and multivariate analyses of the entire cohort, propensity score matching resulted in two groups of 86 patients each: (1) PVI plus LA roof ablation (PVI-plus group) and (2) PVI alone (PVI-only group). The primary endpoint was the first documented > 30-s arrhythmia recurrence after a 3-month blanking period. PVI was successful in all patients. A bidirectional conduction block across the LA roof was verified in 91.9% of patients in the PVI-plus group. During a median mid-term follow-up of 33months, 21 patients (24.4%) in the PVI-plus group and 37 patients (43.0%) in the PVI-only group (P = 0.01) reached the primary endpoint. Multivariate analysis revealed AF history > 2years (hazard ratio [HR] = 2.04, P < 0.01), LA area > 21cm2 (HR = 2.36, P < 0.01), female sex (HR = 1.92, P = 0.02), and LA roof ablation (HR = 0.47, P < 0.01) as significant predictors of outcome. We observed a significant difference in arrhythmia recurrence rates between the two groups. LA roof ablation is an effective adjuvant treatment option that shows improved outcome compared with PVI alone.

Clinical outcome and left atrial function after left atrial roof ablation using the cryoballoon technique in patients with symptomatic persistent atrial fibrillation

IntroductionThere are no data concerning clinical outcome and left atrial (LA) function after LA roof ablation using a second-generation cryoballoon (CB) for treatment of persistent atrial fibrillation (AF). Here, we report the first follow-up results after pulmonary vein isolation (PVI) plus LA roof ablation with the CB technique in patients with symptomatic persistent AF. Methods and resultsWe enrolled 107 consecutive patients who underwent CB ablation at our institution with the aim of PVI and bidirectional conduction block across the LA roof. Clinical success was defined as freedom from >30-s recurrence of AF, atrial flutter, or atrial tachycardia after a 3-month blanking period. Follow-up data were collected during outpatient clinic visits. LA volume, LA emptying fraction, and LA expansion index (parameters of LA function) were evaluated by echocardiography before and 3 months after ablation.PVI was achieved in all patients, and bidirectional conduction block was verified in 91.6%. Median follow-up duration was 31 (interquartile range 11/44) months. PVI plus LA roof ablation was sufficient to restore and maintain sinus rhythm in 72.9% (n = 78) of patients. The overall complication rate was 1.8%. LA volumes decreased significantly after ablation (P < 0.05), whereas total LA emptying fraction (P = 0.25) and LA expansion index (P = 0.32) were preserved within the 3-month follow-up. ConclusionsLA roof ablation combined with PVI using the CB technique is a safe and effective adjuvant treatment with a promising midterm outcome and preserved LA function 3 months after ablation.

Abstract 17376: Risk of Early Reablation Post Cryoballoon Ablation

Introduction: Post-ablation radiofrequency tissue friability has been described; however, tissue friability post cryoablation has not been well studied. We report a case of left atrial perforation with normal contact force radiofrequency ablation 22 days after initial cryoballoon ablation. Description: A 59-year-old male with persistent atrial fibrillation, severe biatrial enlargement, non-ischemic cardiomyopathy (EF of 20%), underwent initial cryoballoon pulmonary vein isolation with left atrial roof cryoablation with restoration of sinus rhythm and no complications. Patient presented 22 days later with sustained atrial flutter and heart rate over 130 bpm refractory to aggressive medical management, cardioversion, and acute on chronic congestive heart failure. Early re-ablation was performed with electrophysiology study and 3D activation map confirming ectopic atrial tachycardia foci arising from left atrial roof, anterior to the border of previously cryo-ablated region. St. Jude TactiCath™ contact force ablation catheter, was used to ablate this foci, and termination within 5 seconds of ablation was observed. Using the Force-Time Integral index to guide further ablation, the surrounding area was ablated for an additional 20 seconds at 30 W with a maximum recorded contact force throughout the procedure of 35 grams, and an average of 10-15 grams.A decrease in systolic blood pressure from 120 mmHg to 80 mmHg was noted, and intracardiac ultrasound confirmed 1.5 cm of pericardial effusion. Successful pericardiocentesis and reversal of anticoagulation was performed with ongoing bleeding, and eventual surgical intervention was required. On direct visualization during surgery, the left atrial roof perforation was confirmed, and was noted to be very friable and difficult to retain suture for repair. Patient did well post-operatively and was discharged with no recurrence of arrhythmias. Conclusions: Despite standard of care monitoring, including force-time integral index and contact-sensing catheters, atrial perforation occurred likely due to increased tissue friability post initial cryoablation. The optimal timing for repeat ablation is not completely understood, and extreme caution and avoidance of early re-ablation risk is prudent.

How to Control Subannular Hemorrhage during Aortic Root Enlarging Procedures.

We describe an effective suture technique to control the persistent subannular bleeding at the aortoventricular curtain in four patients with aortic stenosis and small annulus who underwent aortic root enlargement and patch reconstruction. This technique approximates the left atrial roof to the aortic root without the need for re-replacement of the aortic prosthesis or revision of the patch. Reintervention for aortic root, valve, or the residual aorta was not required.

PROCEDURE COMPLEXITY AND COMPLICATIONS IN PULMONARY VEIN ABLATIONS

Atrial Fibrillation a common arrhythmia with a high burden of disease. When medical management fails, pulmonary vein ablation (PVA) can be an effective therapy to treat AF. The most common target for ablation is isolation of the pulmonary veins. Depending on the nature of the AF, additional ablation lesion sets (eg. left atrial roof line, mitral isthmus line, fractionation ablation) may be necessary. Complications from a PVA can be serious, with a risk estimated at approximately 4%. To determine if ablation procedures that involve extra lesions sets in addition to pulmonary vein isolation result in increased complication rates. In this retrospective cohort study, we examined 1374 PVAs performed from 2009 to 2017. Of these, 984 were categorized as simple ablations (pulmonary vein isolation alone) and 390 were categorized as complex (left atrial roof line, mitral isthmus line, or fractionation ablation). Rates of serious complications (tamponade, congestive heart failure, stroke/TIA) and all complications (groin injury, bleed, and other in addition to serious complications) were assessed and compared between simple and complex procedures. Complex procedures had a significantly greater number of ablations (31 vs 21, p = 0.01), longer ablation duration (43 vs. 36 minutes, p < 0.01), longer total fluoroscopy time (20 vs 19 minutes, p = 0.04) and longer procedure time (244 vs 217 minutes, p < 0.01) than simple ablations. Serious complications rates were 1.93% and 2.31% for simple and complex procedures respectively, however the difference between them was not statistically significant (p = 0.67). There was also no statistically significant difference in total complication rates, which were 7.22% and 7.69% for simple and complex procedures respectively (p = 0.76). Complex ablations do require more ablations, more ablation time, increased fluoroscopy time, and increased procedure time. However, we detected no increased overall complication risk comparing complex ablations with simple ablations.

P5753How to create linear conduction block at left atrial roof by cyroballoon catheter

P5753How to create linear conduction block at left atrial roof by cyroballoon catheter

Impact of modified techniques of transcatheter closure in large atrial septal defects (⩾30 mm) with anatomic complexities.

The outcome of transcatheter closure in ostium secundum atrial septal defects is determined by the morphology of the defects. Modified techniques such as balloon assistance, pulmonary vein deployment, left atrial roof technique, and so on are used for circumventing the anatomic complexities and increasing the success rates. We planned a prospective study looking at the outcomes of transcatheter closure in secundum atrial septal defects with modified techniques in different anatomic complexities identified in transoesophageal echocardiography and their association with outcome of transcatheter closure. Transcatheter closure was successful in 295 out of 346 (82%) patients with modified techniques. Balloon-assisted technique offered a success rate of 87%. The mean defect size was 34.7±2.78 mm (95% confidence interval (CI) 30.67-43.1 mm) with success and 40.16±4.5 mm (95% CI 32.16-44.7) with failure (p = 0.02). The mean total septal length was 38.11±0.63 (95% CI 35.21-40.56 mm) with success and 42.54±0.34 (95% CI 38.79-43.21 mm) with failure. The defect to septal ratios were 0.82 and 0.94 in success and failure groups, respectively (p=0.02). However, the absence of a retro-aortic margin, septal aneurysm, and multiple defects did not affect the success rate. Deficient inferior vena caval margin, deficient posterior margin, and size⩾40 mm had a high risk of failure with transcatheter closure. The odds ratio for procedural failure was 25.3 (4.3-143.8) in patients with malaligned septum, 8.3(1.4-48.5) with deficient inferior vena caval margin, and 4.1(2.5-19) for size⩾40 mm. The modified techniques for device deployment offer substantial chances of success in transcatheter closure of secundum atrial septal defects with anatomical complexity (82%). Variants such as defect size of⩾40 mm and deficient inferior and posterior margins have high failure rates with a modified technique.

Left Atrial Roof Incision for Mitral Valve Interventions and Left Atrial Mass Resection: A Safe Alternative for Excellent Exposure. A Single Center Experience.

Proper visualization has always been the cornerstone for conducting proper cardiac interventions. Although many incisions have been described for mitral valve exposure, the feasibility of some comes at the expense of proper exposure. When it comes to a small left atrium, larger incisions may venture into critically situated structures, creating a heavy toll of increased morbidity and mortality. We aim to evaluate the safety and efficacy of a superior left atrium approach for mitral valve interventions and left atrial mass resection, particularly in a small left atrium. We present our experience and early results as a retrospective study conducted at Cardiothoracic Surgery Department, Ain-Shams University, Cairo, Egypt. A total of 85 patients underwent mitral valve interventions and left atrial mass resection through limited incision in the left atrial dome. The study included 29 female patients and 56 male patients with a mean age of 42.56 ± 7.39 years. Twenty-seven patients were NYHA class I-II and 58 patients were class III-IV. Mean ejection fraction was 55.47 ± 8.56. Three patients had mitral valve repair, 67 patients had mitral valve replacement, and 15 patients had resection of left atrial myxomas. Preoperative atrial fibrillation was present in 27% of the patients. Two patients had new incidence of atrial fibrillation, one patient had new atrial flutter, and one patient had complete heart block, requiring a permanent pacemaker. No mortality occurred in the series, and three patients needed re-exploration for bleeding. Limited left atrial roof incision provides a safe and feasible exposure for conducting mitral valve interventions and resection of left atrial masses, especially in cases with a small left atrium.

The impact of the CartoSound® image directly acquired from the left atrium for integration in atrial fibrillation ablation.

Intracardiac echocardiographic (ICE) imaging might be useful for integrating three-dimensional computed tomographic (CT) images for left atrial (LA) catheter navigation during atrial fibrillation (AF) ablation. However, the optimal CT image integration method using ICE has not been established. This study included 52 AF patients who underwent successful circumferential pulmonary vein isolation (CPVI). In all patients, CT image integration was performed after the CPVI with the following two methods: (1) using ICE images of the LA derived from the right atrium and right ventricular outflow tract (RA-merge) and (2) using ICE images of the LA directly derived from the LA added to the image for the RA-merge (LA-merge). The accuracy of these two methods was assessed by the distances between the integrated CT image and ICE image (ICE-to-CT distance), and between the CT image and actual ablated sites for the CPVI (CT-to-ABL distance). The mean ICE-to-CT distance was comparable between the two methods (RA-merge = 1.6 ± 0.5mm, LA-merge = 1.7 ± 0.4mm; p = 0.33). However, the mean CT-to-ABL distance was shorter for the LA-merge (2.1 ± 0.6mm) than RA-merge (2.5 ± 0.8mm; p < 0.01). The LA, especially the left-sided PVs and LA roof, was more sharply delineated by direct LA imaging, and whereas the greatest CT-to-ABL distance was observed at the roof portion of the left superior PV (3.7 ± 2.8mm) after the RA-merge, it improved to 2.6 ± 1.9mm after the LA-merge (p < 0.01). Additional ICE images of the LA directly acquired from the LA might lead to a greater accuracy of the CT image integration for the CVPI.

Optimalendpoint for catheter ablation of longstanding persistent atrial fibrillation: A randomized clinical trial.

In longstanding persistent atrial fibrillation (LPeAF), the ideal endpoint of ablation remains to be determined. This study was to explore the value of pursuing AF termination or no with the same strategy during ablation on the long-term outcomes in patients with LPeAF. Utilized "CCL" strategy is a fixed ablation approach consisting of circumferential pulmonary vein antrum isolation, ablation of complex fractionated atrial electrogram, and linear ablation between two anatomical structures (the mitral isthmus, left atrial roof). Note that 400 patients were randomized to group A (technical endpoint) and group B (pursuing AF termination). A group with technical endpoint had lower rate of acute AF termination (AF→sinus rhythm, 3.5%vs 18.1%; AF→atrial tachycardia, 23.7%vs 44.7%; P<0.01) and shorter duration of ablation (164.9 ± 20.8vs 223.4 ± 24.9, P<0.01), radiofrequency delivery time (69.8 ± 18.1vs 102.2 ± 26.3, P<0.01), and x-ray exposure time (18.2 ± 8.8vs 27.9 ± 12.4, P<0.01) than those in B group (pursuing AF termination). During follow-up, freedom from atrial arrhythmias didnotdifferbetweenthetwo groups after a single ablation procedure (46.5%vs 54.3%, P=0.12) and the final ablation procedure (60.1%vs 65.8%, P=0.24). In patients of LPeAF, pursuing AF termination during ablation was associated with similar long-term clinical outcome compared to that with technical endpoint. Ablation to termination is not the best strategy during ablation.

Revisiting anatomic macroreentrant tachycardia after atrial fibrillation ablation using ultrahigh-resolution mapping: Implications for ablation

Anatomic macroreentrant atrial tachycardias (MATs) are conventionally reported to depend on the cavotricuspid isthmus, the mitral isthmus, or the left atrial roof, and are commonly seen following catheter ablation for atrial fibrillation. To define the precise circuits of anatomic MAT with ultrahigh-resolution mapping. In 57 patients (mean age, 62 years; 10 female) who developed ≥1 anatomic MAT, we analyzed 88 MAT circuits including 16 peritricuspid, 42 perimitral, and 30 roof-dependent circuits, using high-density mapping and entrainment. Of 16 peritricuspid atrial tachycardias (ATs), 8 (50.0%) showed a circuit not limited to the tricuspid annulus. However, cavotricuspid isthmus ablation terminated the tachycardia in all patients. Similarly, 26 of 42 perimitral ATs (61.9%) showed a circuit not limited to the mitral annulus, and a low-voltage zone <0.1 mV around the mitral annulus was associated with nontypical perimitral ATs (P < .0001). The practical isthmus was not in the mitral isthmus in 13 of these 26 perimitral ATs (50%). Finally, 22 of 30 roof-dependent ATs (73.3%) had a circuit not rotating around both pairs of pulmonary veins. Brief assessment of the activation direction on the posterior wall in relation to that on the septal, anterior, and lateral wall helped deduce the circuit of roof-dependent AT in 27 of 30 (90.0%). Practical isthmus was not in the roof in 8 of 22 (36.4%). Practical isthmuses mapped with the system were significantly shorter than the usual anatomic isthmuses (16.1 ± 8.2 mm vs 33.7 ± 10.4 mm) (P < .0001). High-density mapping successfully identified the precise circuits and the practical isthmus of anatomic MATs in patients with prior atrial fibrillation ablation.

Left atrial remodeling: Regional differences between paroxysmal and persistent atrial fibrillation

BackgroundThe mechanisms underlying self-perpetuation of persistent atrial fibrillation (AF) are not well understood. To gain insight into these mechanisms, we conducted a study comparing left atrial (LA) electroanatomic maps obtained during sinus rhythm between patients with paroxysmal AF (PAF) and patients with persistent AF (PerAF). MethodsThe study included 23 men with PAF (age, 56.3±12.1 years) and 13 men with PerAF (age, 54.3±13.4 years). LA voltage mapping was performed during sinus rhythm. The clinical and electroanatomic characteristics of the two groups were evaluated and analyzed statistically. ResultsThe bipolar voltages at the LA septum, roof, and posterior wall, right superior pulmonary vein (PV) and its antrum, right superior PV carina, and right inferior PV antrum were significantly lower in patients with PerAF than in those with PAF. The bipolar voltages in other parts of the LA did not differ statistically between the two groups. ConclusionPAF and PerAF seem to be characterized by differences in the regional voltage in the LA and PVs. The LA structural remodeling of PerAF may initiate from the right PVs and their antra and LA septum, roof, and posterior wall.

Right atrial diameter and outcome of catheter ablation of atrial fibrillation.

While AF is considered more like a left atrial (LA) disease, to what extent the right atrium contributes to the pathogenesis and ablation outcome of AF remains unclear. This study aimed to identify if right atrial diameter (RAD) could predict arrhythmia recurrence after catheter ablation of atrial fibrillation (AF). Four hundred and seventy patients with drug-resistant AF [paroxysmal AF (PAF) 196; non-PAF 274] who underwent primary catheter ablation were enrolled. Ablation strategy included complete bilateral pulmonary vein isolation (PVI) in all patients and additional linear ablation across mitral isthmus, LA roof, and tricuspid isthmus in non-PAF cases. Risk factors associated with recurrence were determined by a Cox regression model, and the predictive power was evaluated by using receiver operating characteristic curve. After 24.3±18.0months, 284 patients (60.6%) experienced atrial tachyarrhythmia recurrence (111 in PAF, 173 in non-PAF). RAD was moderately associated with LA diameter (r=0.371, P<0.001), left ventricular ejection fraction (r=-0.205, P<0.001), and left ventricular end-diastolic diameter (r=0.319, P<0.001). Multivariate Cox regression analysis demonstrated that RAD was an independent predictor for recurrence only in PAF patients with LAD ≥35mm (HR 1.044, 95% CI 1.007-1.082, P=0.021). The RAD cutoff value of 35.5mm predicts atrial tachyarrhythmia recurrence with 85.4% sensitivity and 29.2% specificity. Kaplan-Meier analysis indicated that RAD over 35.5mm is associated with more recurrence after PAF ablation (log-rank P=0.034), comparing to those with RAD <35.5mm. RAD predicts outcome of ablation only in patients with PAF and concurrent LA enlargement. Under this condition, RAD <35.5mm is associated with a more favorable recurrence-free survival at over 2-year follow-up.

Atrial Tachycardias After Surgical AtrialFibrillation Ablation: Clinical Characteristics, Electrophysiological Mechanisms, and Ablation Outcomes From a Large, Multicenter Study.

The clinical characteristics, electrophysiological mechanisms, and ablation outcomes of post-surgical atrial fibrillation ablation (SAFA) atrial tachycardias (ATs) have not been studied in a large, multicenter cohort. ATs are often seen following SAFA. Analysis was performed on 137 patients (age, 62 ± 10 years; 74% male) who underwent catheter ablation for symptomatic post-SAFA AT from 2004 to 2013 at 3 high-volume institutions in the United States. A total of 137 patients had 149 ATs that were mapped; 103 (69%) had a left atrial (LA) origin and 46(31%) had a right atrial origin. Of the 149, a total of 44 (30%) had a focal mechanism, with 29 (66%) having an LA origin, with53% localized to LA posterior wall. Of the 105 re-entrant ATs, 74 (71%) were of LA origin. Thepredominant circuits were cavotricuspid isthmus (n= 25), perimitral (n= 19), LA roof (n= 17), left pulmonary veins(n= 13), right pulmonary vein/LA septum (n= 12), and LA appendage (n= 7). A total of 93% of patients had≥1 pulmonary vein reconnection requiring reisolation. Catheter ablation resulted in termination and noninducibility of 97% of right atrial and 93% of LAATs. Over a 12-month follow-up, 80% of patients were free ofany AT or AF. In this large multicenter cohort of post-SAFA ATs, most were of LA origin, with macro-re-entry being the most common arrhythmia mechanism. Wide variability in location of AT circuits was seen in both right atrialand LA andlikely reflects underlying arrhythmogenic substrate and differences in modified SAFA techniques. Catheterablation was highly successful in eliminating the culprit AT with favorable long-term outcomes.

Arrhythmogenic left atrial roof vein

A seventy year-old male was referred to our hospital to undergo radiofrequency catheter ablation (RFCA) for drug-refractory paroxysmal atrial fibrillation (AF). Pre-operative three-dimensional computed tomography revealed a unique left atrial (LA) roof vein. Electrophysiological findings showed expansion of the myocardial sleeve and local firing in the LA roof vein. We performed isolation of this arrhythmogenic abnormal vein concomitant with general pulmonary vein isolation in this case, and AF did not recur after the procedure.

Association Between Local Bipolar Voltage and Conduction Gap Along the Left Atrial Linear Ablation Lesion in Patients With Atrial Fibrillation

A bipolar voltage reflects a thick musculature where formation of a transmural lesion may be hard to achieve. The purpose of this study was to explore the association between local bipolar voltage and conduction gap in patients with persistent atrial fibrillation (AF) who underwent atrial roof or septal linear ablation. This prospective observational study included 42 and 36 consecutive patients with persistent AF who underwent roof or septal linear ablations, respectively. After pulmonary vein isolation, left atrial linear ablations were performed, and conduction gap sites were identified and ablated after first-touch radiofrequency application. Conduction gap(s) after the first-touch roof and septal linear ablation were observed in 13 (32%) and 19 patients (53%), respectively. Roof and septal area voltages were higher in patients with conduction gap(s) than in those without (roof, 1.23 ± 0.77 vs 0.73 ± 0.42mV, p= 0.010; septal, 0.96 ± 0.43 vs 0.54 ± 0.18mV, p= 0.001). Trisected regional analyses revealed that the voltage was higher at the region with a conduction gap than at the region without. Complete conduction block across the roof and septal lines was not achieved in 3 (7%) and 6 patients (17%), respectively. Patients in whom a linear conduction block could not be achieved demonstrated higher ablation area voltage than those with a successful conduction block (roof, 1.91 ± 0.74 vs 0.81 ± 0.51mV, p= 0.001; septal, 1.15 ± 0.56 vs 0.69 ± 0.31mV, p= 0.006). In conclusion, a high regional bipolar voltage predicts failure to achieve conduction block after left atrial roof or septal linear ablation. In addition, the conduction gap was located at the preserved voltage area.

Neural substrate of posterior left atrium: A novel modulation for inducibility and remodeling of atrial fibrillation in canine.

BackgroundThe neural mechanism of posterior left atrium (PLA) for genesis of atrial fibrillation has not been completely elucidated. We sought to assess the contribution of PLA denervation on atrial fibrillation (AF) inducibility and atrial remodeling.Methods and resultsAfter left thoracotomy in anesthetized dogs (n = 32), electrode catheters were attached to the PLA, left atrial roof, left pulmonary vein and left atrial appendage. Experiment 1 (n = 16): Vagal stimulation (VS group, n = 8) led to more pronounced ERP shortening in PLA than in other sites (CTL:71±7 ms vs VS: 52±6 ms, P<0.05;). Compared with control group (CTL group, n = 8), atropine alone or with propranolol applied to PLA greatly inhibited VS-induced ERP shortening, ERP dispersion increase, and AF inducibility in the left atrium (P<0.05); but ERP was not significantly different between atropine alone and DB conditions (Atro:85±8 ms vs DB:90±9ms, P>0.05). In addition, domain frequency (DF) of VS-induced AF waveform was not affected by atropine alone, while selective double autonomic blockade at PLA significantly decreased DF at all sites (P<0.05). Experiment 2 (n = 16): In group 1 (n = 8), ERP was markedly shortened in the first 2 hours (11–19% decrease) and then stabilized; however, WOV was progressively widened throughout the 6 hours rapid atrial pacing (BS: 51±9ms vs 6th hour: 161±30ms, P<0.05). After drug application, ERP was increased in all sites of atria, the ERP dispersion was significantly decreased (Atro: 2.36±0.02 vs 6th hour: 5.09±0.07, P<0.05) and AF could be induced in only 1 of 8 dogs. In group 2 (n = 8), 6 hours rapid atrial pacing failed to shorten the ERP and increased ERP dispersion, and only 2 episodes of AF could be induced (WOV = 0).ConclusionLocal denervation of PLA, as predominant atrial autonomic profile, greatly inhibits AF inducibility and atrial remodeling.