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Introduction: The mechanisms leading to the conversion of atrial fibrillation (AF) to sinus rhythm are poorly understood. This study describes the dynamic behavior of electrophysiological parameters and conduction patterns leading to spontaneous and pharmacological AF termination. Methods: Five independent groups of goats were investigated: (1) spontaneous termination of AF, and drug-induced terminations of AF by various potassium channel inhibitors: (2) AP14145, (3) PA-6, (4) XAF-1407, and (5) vernakalant. Biatrial contact mapping was performed during an open chest surgery and intervals with continuous and discrete atrial activity were determined. AF cycle length (AFCL), conduction velocity and path length were calculated for each interval, and the final conduction pattern preceding AF termination was evaluated. Results: AF termination was preceded by a sudden episode of discrete activity both in the presence and absence of an antiarrhythmic drug. This episode was accompanied by substantial increases in AFCL and conduction velocity, resulting in prolongation of path length. In 77% ± 4% of all terminations the conduction pattern preceding AF termination involved medial to lateral conduction along Bachmann's bundle into both atria, followed by anterior to posterior conduction. This finding suggests conduction block in the interatrial septum and/or pulmonary vein area as final step of AF termination. Conclusion: AF termination is preceded by an increased organization of fibrillatory conduction. The termination itself is a sudden process with a critical role for the interplay between spatiotemporal organization and anatomical structure. [ABSTRACT FROM AUTHOR]

Conventional right atrial appendage pacing (RAAp) is associated with adverse clinical outcomes mediated in part by electromechanical atrial delays. Bachmann's bundle pacing (BBp) offers more physiologic atrial activation; however, detailed analysis of pacing site on paced P wave parameters is lacking. Intraprocedural electrocardiograms of 21 consecutive patients undergoing atrial lead implantation were retrospectively analyzed and within-patient comparisons of 7 P wave parameters (P wave duration, P wave voltage, P wave area, PR interval, PR segment, PTFV1 and P wave axis) during sinus rhythm, RAAp and BBp performed. The median basal P wave duration was prolonged at 134.5 ms (Q1,Q3: 120.5, 150.5) and similarly prolonged during RAAp at 144.0 ms (127.0, 176.0) but was significantly reduced with BBp at 98.0 ms (93.0, 116.0; p = 0.005 and p < 0.001, respectively). The median basal P wave voltage in lead II was normal at 0.11 mV (0.08, 0.15) but significantly reduced during RAAp at 0.08 mV (0.04, 0.11) and greatest during BBp at 0.16 mV (0.09, 0.19; p < 0.001 and p = 0.003, respectively). The median basal PR interval was top normal at 185.0 ms (163.0, 213.0) and similarly prolonged during RAAp at 204.0 ms (166.5, 221.0) but was significantly shortened during BBp at 163.0 ms (142.0, 208.0; p = 0.03 and p = 0.001, respectively). BBp has favorable effects on the paced P wave parameters including marked shortening in P wave duration, increase in P wave voltage in lead II and increase in PR segment which may offer significant hemodynamic advantages over conventional RAAp. • Right atrial appendage pacing is associated with interatrial conduction delays. • Prolonged P wave duration is associated with risk of atrial fibrillation. • Bachmann's bundle pacing showed the most favorable effects on P wave indices. • Bachmann's bundle pacing shortened P wave duration and increased P wave voltage. • Bachmann's bundle pacing shortened PR interval while lengthening PR segment. [ABSTRACT FROM AUTHOR]

IntroductionThe mechanisms leading to the conversion of atrial fibrillation (AF) to sinus rhythm are poorly understood. This study describes the dynamic behavior of electrophysiological parameters and conduction patterns leading to spontaneous and pharmacological AF termination.MethodsFive independent groups of goats were investigated: (1) spontaneous termination of AF, and drug-induced terminations of AF by various potassium channel inhibitors: (2) AP14145, (3) PA-6, (4) XAF-1407, and (5) vernakalant. Bi-atrial contact mapping was performed during an open chest surgery and intervals with continuous and discrete atrial activity were determined. AF cycle length (AFCL), conduction velocity and path length were calculated for each interval, and the final conduction pattern preceding AF termination was evaluated.ResultsAF termination was preceded by a sudden episode of discrete activity both in the presence and absence of an antiarrhythmic drug. This episode was accompanied by substantial increases in AFCL and conduction velocity, resulting in prolongation of path length. In 77% ± 4% of all terminations the conduction pattern preceding AF termination involved medial to lateral conduction along Bachmann’s bundle into both atria, followed by anterior to posterior conduction. This finding suggests conduction block in the interatrial septum and/or pulmonary vein area as final step of AF termination.ConclusionAF termination is preceded by an increased organization of fibrillatory conduction. The termination itself is a sudden process with a critical role for the interplay between spatiotemporal organization and anatomical structure.

Background: Despite being increasingly observed in daily practice, epicardial atrial tachycardias (Epi AT) have not been extensively characterized. In the present study, we retrospectively characterize electrophysiological properties, electroanatomic ablation targeting, and outcomes of this ablation strategy. Methods: Patients who underwent scar-based macro-reentrant left atrial tachycardia mapping and ablation patients with at least one Epi AT, which had a complete endocardial map, were selected for the inclusion. Based on current electroanatomical knowledge, Epi ATs were classified based by utilization of following epicardial structures: Bachmann's bundle, septopulmonary bundle, vein of Marshall. Endocardial breakthrough (EB) sites were analyzed as well as entrainment parameters. EB site was targeted for initial ablation. Results: Among seventy-eight patients undergoing scar-based macro-reentrant left atrial tachycardia ablation, fourteen (17.8%) patients met the inclusion criteria for Epi AT and were included in the study. Sixteen Epi ATs were mapped, four utilizing Bachmann's bundle, five utilizing septopulmonary bundle, and seven utilizing vein of Marshall. Fractionated, low amplitude signals were present at EB sites. Rf terminated the tachycardia in ten patients; activation changed in five patients and in one patient atrial fibrillation ensued. During the follow-up, there were three recurrences. Conclusions: Epicardial left atrial tachycardias are a distinct type of macro-reentrant tachycardias that can be characterized by activation and entrainment mapping, without need for epicardial access. Endocardial breakthrough site ablation reliably terminates these tachycardias with good long-term success. [ABSTRACT FROM AUTHOR]

Background: Bachmann's bundle plays a crucial role in the physiology of interatrial signal conduction. In the 1970s, Bayes de Luna introduced the definition of interatrial blocks (IABs), which negatively influence atrioventricular (AV) synchrony and left atrial (LA) activation. We aimed to assess the potential of LA strain technology in evaluating the mechanics of LA in patients with correct conduction and IABs. Additionally, we measured the parameters of regurgitation in pulmonary veins (PV), which depend on the type of interatrial conduction. Material and methods: The study group comprised 51 patients (26 male, 25 female) with symptomatic COVID-19 and sinus rhythm. Our study analyzed their medical history, electrocardiography (ECG) and echocardiography, including the LA strain parameters. Results: Global peak atrial longitudinal strain (PALS) depended on P-wave duration, LA volume, left ventricular ejection fraction (LVEF) and inferior pulmonary veins (PV) regurgitation parameters. Global peak atrial contractile strain (PACS) statistically depends on the LVEF, LA volume and the P-wave morphology. Conclusions: The presence of IABs negatively influences PACS and PALS. Examining LA strain is complementary to accurate ECG, which may be helpful in everyday clinical practice, particularly in diagnosing heart failure with preserved ejection fraction (HFpEF) and as a predictor of new episodes of atrial fibrillation (AF). [ABSTRACT FROM AUTHOR]

An anatomical understanding of the atrial myocardium is crucial for surgeons and interventionists who treat atrial arrhythmias. We reviewed the anatomy of the inter-nodal and intra-atrial conduction systems. The anterior inter-nodal route (#1) arises from the sinus node and runs through the ventral wall of the atrial chambers. The major branch of route #1 approaches the atrioventricular node from the anterior aspect. Other branches of route #1 are Bachmann’s bundle and a vestibular branch around the tricuspid valve. The middle inter-nodal route (#2) begins with a broad span of fibers at the sinus venarum and extends to the superior limbus of the oval fossa. The major branch of route #2 joins with the branch of route #1 at the anterior part of the atrioventricular node. The posterior inter-nodal route (#3) is at the terminal crest and gives rise to many branches at the pectinate muscles of the right atrium and then approaches the posterior atrioventricular node after joining with the vestibular branch of route #1. The branches of the left part of Bachmann’s bundle and the branches of the second inter-nodal route form a thin myocardial network at the posterior wall of the left atrium. These anatomical structures could be categorized into major routes and side branches. There are 9 or more anatomical circles in the atrial chambers that could be structural sites for macro re-entry. The implications of normal and abnormal structures of the myocardium for the pathogenesis and treatment of atrial arrhythmias are discussed.

Abstract Background The hybrid approach has become the most effective treatment option for restoring sinus rhythm and reducing the risk of atrial fibrillation (AF) recurrence. However, several issues remain to be clearly defined, including the appropriate timing of the staged procedure and the most effective strategy. Methods Over a 12-year period of activity, we performed 609 AF ablation procedures via a right mini-thoracotomy. From this general population, 60 patients underwent a hybrid procedure with catheter ablation performed at least 4 weeks after the surgical procedure to confirm if effective complete electrical isolation of pulmonary veins was achieved. In 20 patients, the second stage procedure was performed during the same hospitalization due to patient’s electrical instability. The results obtained in immediate versus staged patients were compared. Results All patients were discharged after the first stage procedure in sinus rhythm. The 20 immediate patients had a shorter hospital stay compared with the staged patients, in whom the two hospitalizations resulted in a longer hospital stay (immediate 5.5 ± 1.6 days versus staged 8.7 ± 1.4, P

Introduction: Recent reports highlighted the role of epicardial connections in the development of biatrial tachycardia circuits. Methods: We reported a case of 60‐year‐old female patient who was admitted with recurrent atrial tachycardia (AT) after endocardial pulmonary vein isolation and anterior mitral line formation. Results: Epicardial activation map demonstrated fragmented continuous potentials at the Bachmann's bundle region with good entrainment response. Epicardial radiofrequency ablation terminated AT with complete block in the anterior mitral line. Conclusions: This case corroborates the data relevant to the role of interatrial connections—specifically Bachmann's bundle—in biatrial macroreentrant ATs and demonstrates that epicardial mapping is an effective method to identify the entire reentrant circuit. [ABSTRACT FROM AUTHOR]

Aims Conventional right atrial appendage (RAA) pacing is associated with increased atrial activation time resulting in higher incidences of atrial tachyarrhythmia. Optimal pacing sites ideally shorten inter-atrial conduction delay, thereby decreasing atrial excitation time. We therefore examined the impact of programmed electrical stimulation (PES) from the right atrium (RA) and left atrium (LA) on the electrophysiological properties of Bachmann's bundle (BB). Methods and results High-resolution epicardial mapping of BB was performed during sinus rhythm (SR) and PES in 34 patients undergoing cardiac surgery. Programmed electrical stimulation was performed from the RAA, junction of the RA with inferior caval vein (LRA), and left atrial appendage (LAA). Pacing from either the RAA or LAA resulted in, respectively, right- and left-sided conduction across BB. However, during LRA pacing in most patients (n = 15), activation started in the centre of BB. The total activation time (TAT) of BB during RAA pacing [63 (55–78) ms] was similar to that of SR [61 (52–68) ms, P = 0.464], while it decreased during LRA [45 (39–62) ms, P = 0.003] and increased during LAA pacing [67 (61–75) ms, P = 0.009]. Reduction of both conduction disorders and TAT was most often achieved during LRA pacing (N = 13), especially in patients who already had a higher amount of conduction disorders during SR [9.8 (7.3–12.3) vs. 4.5 (3.5–6.6)%, P < 0.001]. Conclusion Pacing from the LRA results in a remarkable decrease of TAT compared with pacing from the LAA or RAA. As the most optimal pacing site varies between patients, individualized positioning of the atrial pacing lead guided by mapping of BB may be one of the new frontiers for atrial pacing. [ABSTRACT FROM AUTHOR]

BackgroundImpairment of conduction across Bachmann’s Bundle (BB) may cause advanced interatrial block (a-IAB), which in turn is associated with development of atrial fibrillation. However, the exact relation between a complete transverse line of conduction block (CB) across BB and the presence of a-IAB has not been studied.ObjectiveThe aims of this study are to determine whether (1) a complete transversal line of CB across BB established by high resolution mapping correlates with a-IAB on the surface ECG, (2) conduction abnormalities at the right and left atria correlate with a-IAB, and (3) excitation patterns are associated with ECG characteristics of a-IAB.MethodsWe included 40 patients in whom epicardial mapping revealed a complete transverse line of CB across BB. Pre-operative ECGs and post-operative telemetry were assessed for the presence of (a) typical a-IAB and de novo early post-operative AF (EPOAF), respectively. Total atrial excitation time (TAET) and RA-LA delay were calculated. Entry site and trajectory of the main sinus rhythm wavefront at the pulmonary vein area (PVA) were assessed.ResultsThirteen patients were classified as a-IAB (32.5%). In the entire atria and BB there were no differences in conduction disorders, though, patients with a-IAB had an increased TAET and longer RA-LA delay compared to patients without a-IAB (90.0 ± 21.9 ms vs. 74.9 ± 13.0 ms, p = 0.017; 160.0 ± 27.0 ms vs. 136.0 ± 24.1 ms, p = 0.012, respectively). Patients with typical a-IAB solely had caudocranial activation of the PVA, without additional cranial entry sites. Prevalence of de novo EPOAF was 69.2% and was similar between patients with and without a-IAB.ConclusionA transverse line of CB across BB partly explains the ECG characteristics of a-IAB. We found atrial excitation patterns underlying the ECG characteristics of both atypical and typical a-IAB. Regardless of the presence of a-IAB, the clinical impact of a complete transverse line of CB across BB was reflected by a high incidence of de novo EPOAF.

Background: The hybrid approach has become the most effective treatment option for restoring sinus rhythm and reducing the risk of atrial fibrillation (AF) recurrence. However, several issues remain to be clearly defined, including the appropriate timing of the staged procedure and the most effective strategy.Methods: Over a 12-year period of activity, we performed 609 AF ablation procedures via a right mini-thoracotomy. From this general population, 60 patients underwent a hybrid procedure with catheter ablation performed at least 4 weeks after the surgical procedure to confirm if effective complete electrical isolation of pulmonary veins was achieved. In 20 patients, the second stage procedure was performed during the same hospitalization due to patient's electrical instability. The results obtained in immediate versus staged patients were compared.Results: All patients were discharged after the first stage procedure in sinus rhythm. The 20 immediate patients had a shorter hospital stay compared with the staged patients, in whom the two hospitalizations resulted in a longer hospital stay (immediate 5.5 ± 1.6 days versus staged 8.7 ± 1.4, P < 0.001). A significantly higher number of immediate patients had an associated ablation of the Bachmann's bundle (n = 16 in the immediate group [80%] versus n = 14 in the staged group [45%]; P = 0.001). After a mean follow-up of 74 months, there was no significant difference in the risk of AF relapse between groups (immediate 1/20 [5%] versus staged 7/40 [17.5%]; P = 0.18).Conclusion: The hybrid approach for the treatment of AF was safe and effective in immediate restoring sinus rhythm and in its maintenance at follow-up. Our preliminary results show that both immediate and staged procedures show similar efficacy but this result is strongly influenced by the concomitant ablation of the Bachmann's bundle, which appears to be the most important component of the treatment strategy in order to reduce the risk of recurrent AF. [ABSTRACT FROM AUTHOR]

Abstract Background The termination of bi‐atrial tachycardia (BiAT) via the ablation of the Bachmann's bundle (BB) and mitral isthmus (MI) has been previously reported; however, the strategy and long‐term results of catheter ablation for BiAT remain unclear. Methods The data of nine patients with BiAT who underwent low voltage zone (LVZ) ablation of the left atrial anterior wall (LAAW) after pulmonary vein isolation were reviewed. Patients with a P wave duration 100 ms underwent BB ablation. Results MI ablation was performed in three patients and six patients underwent BB ablation. The difference in the P wave duration before and after ablation was significantly different between the ablation sites (MI group: 5.0 ms difference; BB group; 38.5 ms difference; P = .024). The P wave duration was prolonged by >20 ms and was 120 ms or more after ablation in 5/6 patients who underwent BB ablation. The total recurrence rate was 11.0% (mean: 26.9 months). Conclusion The recurrence of BiAT after MI or BB ablation is low. When BB ablation was performed, the P wave duration was prolonged by >20 ms and was at least 120 ms after the ablation, which may be an endpoint that can be used to measure the success of the ablation.

This article reviews the structure of the atrial chambers to consider the anatomic bases for obstacles and barriers in atrial flutter. In particular, the complex myocardial arrangement and composition of the cavotricuspid isthmus could account for a slow zone of conduction. Prominent muscle bundles within the atria and interatrial, and myoarchitecture of the walls, could contribute to preferential conduction pathways. Alterations from tissue damage as part of aging, or from surgical interventions could lead to re-entry. [ABSTRACT FROM AUTHOR]

Background: Catheter-based or surgical procedures in patients with long-standing persistent atrial fibrillation (LSPAF) remain a challenge. As a result, different approaches including hybrid (surgical and endocardial) ablation have been developed. Bachmann's bundle (BB) is a mainly epicardial structure capable of sustaining arrhythmic reentry that could be involved in the development and perpetuation of atrial fibrillation. We investigated the efficacy and safety of an adjunctive BB ablation in LSPAF patients undergoing hybrid ablation. Methods: In a two-arm non-randomized study, consecutive LSPAF patients undergoing epicardial isolation of pulmonary veins with left atrial posterior wall (box lesion) with (n = 30, BB group) and without additional BB ablation (n = 30, CONV group) were enrolled in the study. All patients underwent an endocardial procedure within 6 weeks post-surgery to assess for potential lesion gaps and additional atrial substrate modification. The primary endpoint was freedom from AF through 12 months of follow-up. Results: The two-staged hybrid ablation was successfully completed in all patients. One-year freedom from atrial arrhythmias recurrence rates was 96.6% in the BB group vs 76.6% in the CONV group (p = 0.025). At procedure completion, 30 (100%) and 17 (56%) patients had a spontaneous cardioversion in BB and CONV group, respectively (p < 0.001). No significant differences in quality of life or complication rates were observed. Conclusions: This initial experience shows, for the first time, that adjunctive BB ablation in the setting of hybrid ablation for LSPAF is a feasible and effective approach in increasing maintenance of sinus rhythm without increasing complication rates. [ABSTRACT FROM AUTHOR]

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A 57-year-old man underwent his seventh ablation session for atrial tachycardia (AT). His previous ablations involved several regions of the right atrium (RA) and left atrium (LA). The AT was characterized as biatrial tachycardia with a circuit involving the mitral annulus and septal RA. The AT was terminated by ablation through the insertion site of Bachmann’s bundle (BB) in both atria. After 3 months, the patient underwent his eighth ablation session because of AT recurrence. Activation maps showed that the connection from the RA to LA and vice versa was maintained via BB and the coronary sinus, respectively. The ablation target to interrupt the AT circuit was the mitral isthmus (MI), not BB, because BB supplied the electrical activation of the left atrial appendage (LAA) via a unidirectional electrical connection from the RA to LA. Ablation attempts from within the coronary sinus were performed to target the epicardial connection in the MI and led to complete blockage of the connection from the LA to RA. Otherwise, the connection from the RA to LA was preserved via BB. The patient was free of symptoms and anti-arrhythmic drugs at the 4-month follow-up. However, he had a high risk of electrical isolation of the LAA because extensive ablations had been performed; the strategy of targeting the MI contributed to the balance between preserving the electrical activation of the LAA and treating the biatrial tachycardia. Verification of the connective pathway between the two atria might be helpful to determine the optimal target.

We present a case of advanced interatrial block induced by flecainide toxicity. We discuss the implications of this conduction abnormality. [ABSTRACT FROM AUTHOR]

Background: Outcomes of catheter ablation (CA) among patients with nonparoxysmal atrial fibrillation (AF) are largely disappointing. Objective: We sought to evaluate the feasibility, effectiveness, and safety of a single‐stage stepwise endo‐/epicardial approach in patients with persistent/longstanding‐persistent AF. Methods: We enrolled 25 consecutive patients with symptomatic persistent (n = 4) or longstanding‐persistent (n = 21) AF and at least one prior endocardial procedure, who underwent CA using an endo‐/epicardial approach. Our anatomical stepwise protocol included multiple endocardial as well as epicardial (Bachmann's bundle [BB] and ligament of Marshall ablations) components, and entailed ablation of atrial tachycardias emerging during the procedure. The primary outcome was freedom from any AF/atrial tachycardia episode after a 3‐month blanking period. The secondary outcome was patients' symptom status during follow‐up. Results: The stepwise endo‐/epicardial approach allowed sinus rhythm restoration in 72% of patients, either directly (n = 6, 24%) or after AF organization into atrial tachycardia (n = 12, 48%). BB's ablation was commonly implicated in arrhythmia termination. After a median follow‐up of 266 days (interquartile range, 96 days), survival free from AF/atrial tachycardia was 88%. Antiarrhythmic drugs could be discontinued in 22 patients (88%). As compared to baseline, more patients were asymptomatic at 9‐month follow‐up (0% vs. 56%, p =.02). Five patients (20%) developed mild medical complications, whereas one subject (4%) had severe kidney injury requiring dialysis. Conclusion: A single‐stage endo‐/epicardial CA resulted in favorable rhythm and symptom outcomes in a cohort of patients with symptomatic persistent/longstanding‐persistent AF and one or more prior endocardial procedures. Epicardial ablation of BB was commonly implicated in procedural success. [ABSTRACT FROM AUTHOR]

Background: The termination of bi‐atrial tachycardia (BiAT) via the ablation of the Bachmann's bundle (BB) and mitral isthmus (MI) has been previously reported; however, the strategy and long‐term results of catheter ablation for BiAT remain unclear. Methods: The data of nine patients with BiAT who underwent low voltage zone (LVZ) ablation of the left atrial anterior wall (LAAW) after pulmonary vein isolation were reviewed. Patients with a P wave duration <100 ms during sinus rhythm underwent MI ablation and those with a P wave duration >100 ms underwent BB ablation. Results: MI ablation was performed in three patients and six patients underwent BB ablation. The difference in the P wave duration before and after ablation was significantly different between the ablation sites (MI group: 5.0 ms difference; BB group; 38.5 ms difference; P =.024). The P wave duration was prolonged by >20 ms and was 120 ms or more after ablation in 5/6 patients who underwent BB ablation. The total recurrence rate was 11.0% (mean: 26.9 months). Conclusion: The recurrence of BiAT after MI or BB ablation is low. When BB ablation was performed, the P wave duration was prolonged by >20 ms and was at least 120 ms after the ablation, which may be an endpoint that can be used to measure the success of the ablation. [ABSTRACT FROM AUTHOR]

Aims: Evidences suggest that recurrent atrial fibrillation (AF) is associated with left atrial (LA) remodelling. The goal of this study is to establish a method for assessment of LA remodelling and find predictors for the development of AF.Methods and Results: This prospective study included patients without a history of AF who were evaluated using pulsed-wave tissue Doppler imaging (PW-TDI). P-wave onset to A'-wave (PA' interval) was measured at the septal, lateral, anterior, and inferior mitral annulus. Abnormal LA activation pattern was defined as an upward LA activation over the coronary sinus and delayed activation anterior. Left atrial asynchrony was measured as (i) the difference between the septal and lateral PA' interval (DLS) and (ii) the standard deviation of all four PA' intervals (SD4-PA'). The follow-up for AF recurrence (AF+) was based on symptoms and 7-day Holter electrocardiograms. Ninety-eight patients (mean age 58 ± 15 years, 47% female) were included. During a follow-up of 28 ± 9 months, AF was documented in 10%. More pronounced LA asynchrony was observed in AF+ group: DLS (AF+) 39 ± 16 vs. DLS (AF-) 20 ± 11 ms; P < 0.001, and SD4-PA' (AF+) 18.6 ± 6.4 vs. SD4-PA' (AF-) 11.7 ± 4.2 ms; P < 0.001. Abnormal LA activation was frequently observed in AF+ patients: 60% vs. 27%; P = 0.033. Electrocardiogram sign of Bachmann's bundle block (BBB) was associated with prolongation of SD4-PA': SD4-PA' (BBB+) vs. SD4-PA' (BBB-) = 18 ± 6 vs. 13 ± 4.5 ms; P = 0.007.Conclusions: More pronounced LA asynchrony and abnormal LA activation pattern were associated with new-onset AF. [ABSTRACT FROM AUTHOR]

This case describes a 74-year-old male who presented with rapid atrial flutter in association with large atrial lipoma along the interatrial septum. Conversion to sinus rhythm revealed the electrocardiographic criteria for advanced interatrial block. Interatrial block results from disruption of conduction through Bachmann's bundle, most commonly due to progressive atrial fibrosis. Bayés syndrome is recognized as the association of atrial arrhythmias with underlying interatrial block. This case supports the concept that localized disruption of atrial conduction via Bachmann's bundle from an atrial lipoma can produce the electrophysiologic substrate for atrial arrhythmias and the Bayés syndrome. [ABSTRACT FROM AUTHOR]

Background: Functional and structural atrial changes contribute to AF. It decreases conduction velocity and forms intra atrial blocks. In the ECG those changes are manifested by the duration and morphology of the P wave. Material and methods: The study group consisted of 50 patients with atrial fibrillation. There were 27 women and 23 men, aged 65.3 +/- 9.8 years. 22 patients had paroxysmal AF and 28 had persistent AF, in the latter direct current cardio version was performed. Results: In patients with a prolonged episodes of atrial fibrillation the P wave duration was longer in comparison to patients with sinus rhythm (187.1 +/- 31.5 vs 161.1 +/- 18.8 ms; p = 0.006). There were significant differences in P wave duration among the patients with normal and abnormal interatrial conduction, with the longest duration in complete Bachmann's bundle block group (152.7 +/- 17.5 vs 165.3 +/- 15.3 vs 207.9 +/- 27.5 ms; p < 0.001). Conclusions: In patients with persistent atrial fibrillation the duration of the P wave is prolonged in comparison to paroxysmal. In the majority of patients prolongation of the P wave duration is dependent on different forms of conduction block. The morphological changes of P waves are caused by the arrhythmia rather than left atrial hypertrophy. [ABSTRACT FROM AUTHOR]

Biatrial tachycardia (BiAT), involving Bachmann's bundle in the circuit, has sometimes been observed after mitral anterior line ablation. In this article, we present a case of BiAT, involving a long epicardial circuit, composed of Bachmann's bundle and the left atrial ridge (LAR). We discuss the optimal ablation technique for this tachycardia based on our experience in addition to the relationship between Bachmann's bundle and the LAR. Furthermore, the evaluation method for the mitral anterior block line is also discussed. [ABSTRACT FROM AUTHOR]

Atrial pacing is done for either symptomatic sinus node dysfunction (SND) or for maintenance of atrio-ventricular synchrony in a dual chamber pacemaker. Conventionally, atrial lead is placed in the right atrial appendage. Atrial conduction disorder in patients with permanent pacing results in higher incidence of atrial fibrillation. Atrial septal pacing has emerged as a solution to this problem. So, it is extremely important to understand the different features of paced P wave from various atrial pacing sites. Conventional right atrial appendage pacing in presence of atrial conduction disorder results in marked latency with prolonged P wave duration with reduced amplitude. The morphology is similar to sinus rhythm. Atrial septal pacing causes short and sharp P wave with negative polarity in inferior leads and positive polarity in lead V1 in lower septal pacing, whereas positive polarity in inferior leads and negative polarity in lead V1 during pacing from upper septum.

This study evaluated the correlation between interatrial block (IAB) and atrial fibrillation (AF) among patients admitted to our Internal Medicine Unit: 110 (group 1) were identified with electrocardiograms both in sinus rhythm and AF, and 123 (group 2) constantly in sinus rhythm. In both we analyzed: the presence of partial (P≥120 msec) or advanced (P>120 msec and biphasic in D2, D3, aVF) IAB, and the main electrocardiographic and clinical features. Age and gender between the two groups were similar. IAB was present in 89/110 (80.91%,) in group 1 and 26/123 (21.13%) in group 2 (P=0.1 mV (P0.1 mV.

The article presents a case study of a 72‐year‐old man was referred for atypical atrial flutter ablation (AFL). He had a previous history of mitral valve repair due to primary mitral regurgitation, left atrial appendage (LAA) occlusion, and end‐stage renal disease under dialysis. The transthoracic echocardiogram revealed a left ventricular ejection fraction, a dilated LA and no signs of significant mitral regurgitation.

With the publication of scholar Bayes's elaboration on interatrial block, and the subsequent series of studies on interatrial block and its clinical significance, more attention has been paid to conduction block at the level of the atrium in recent years. It has also promoted the further development of related researches, the most important of which is its influence and significance in the occurrence of atrial fibrillation. This paper first introduces the concept of interatrial block, and then focuses on its relativity with new onset and recurrence of atrial fibrillation in different conditions as well as the mechanisms. [ABSTRACT FROM AUTHOR]

This study evaluated the correlation between interatrial block (IAB) and atrial fibrillation (AF) among patients admitted to our Internal Medicine Unit: 110 (group 1) were identified with electrocardiograms both in sinus rhythm and AF, and 123 (group 2) constantly in sinus rhythm. In both groups we analyzed: the presence of partial (P=120 msec) or advanced (P>120 msec and biphasic in D2, D3, aVF) IAB, and the main electrocardiographic and clinical features. Age and gender between the two groups were similar. IAB was present in 89/110 (80.91%) in group 1 and 26/123 (21.13%) in group 2 (P=<0.01); partial in 50/110 (45.45%) and 19/123 (15.7%) in group 1 and 2 respectively (P<0.01), advanced in 39/110 (35.45%) and 7/123 (5.69%) (P<0.019). The correlation between IAB and AF was significant (P<0.001); 36 (65.4%) patients out of 55 with atrial echo dilatation had IAB and 14 (25.4%) had deep terminal negativity of P-wave in V1 (DTNPV1) >0.1 mV (P<0.01). IAB represents a reliable predictor of AF; moreover, the sensitivity of the IAB in detecting atrial dilatation is higher than the DTNPV1 >0.1 mV. [ABSTRACT FROM AUTHOR]

Introduction: A middle‐age woman underwent an electrophysiologic study due to recurrent atypical atrial flutter. Methods and Result: Radiofrequency ablation of cavotricuspid isthmus and anterior mitral line was performed. During energy delivery on the anterior left atrial wall, interatrial dissociation and complete block of the sinus impulse to the atrioventricular (AV) node was observed. AV node activation became dependent on a subsidiary left atrial rhythm. Conclusion: Anatomical location of intra and inter‐atrial connections must be taken into account when performing extensive ablation procedures, specially in cases with prior cardiac surgeries. [ABSTRACT FROM AUTHOR]

Background: Pacing in the Bachmann's bundle (BB) area (upper atrial septum) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation in patients with atrial conduction delay. However, insertion of active fixation lead in the upper atrial septal position is difficult and time consuming with conventional stylet, inhibiting application of this pacing method in routine practice. Methods: The technique of positioning the atrial lead in BB with hand-made stylet is presented with emphasis on electrocardiographic P-wave pattern and fluoroscopic landmarks. Results: The results demonstrate an acute implantation and short-term success of BB pacing of 14 patients out of 15 patients without major complications. Pacing parameters at implantation and 3 months postprocedure were noted which were within normal limits. Conclusion: These favorable initial results indicate that the positioning of active fixation atrial lead in BB with fluoroscopic landmarks is feasible and reproducible with a simple technique.

The author discusses a study by Does and colleagues, published within the issue, which assessed atrial electrophysiological properties of patients without a history of atrial fibrillation (AF) who were undergoing coronary artery bypass surgery. She talks about the procedures that promote the creation of an AF substrate, correlation between atrial electrophysiological properties and age, and aging as a major risk factor for AF.

We present the surface electrocardiogram of an open‐chest anesthetized healthy adult swine after direct application of ice at the transversus sinus of the pericardium where the Bachmann's region is located. Gradual and transient interatrial block (IAB) in the absence of structural atrial disease is described. This new experimental model demonstrated that IAB is an independent entity from left atrial enlargement. [ABSTRACT FROM AUTHOR]

Introduction: The past few years have given rise to extensive research on an interatrial block and its clinical relevance, mainly its association with supraventricular arrhythmias. In 2015, the authors of this article reviewed the Bayes syndrome for the first time and after three years there has been so much evidence accumulated that it seems reasonable to rewrite an update, based fundamentally on the new findings. Focused on its relationship with cardioembolic strokes, today efforts are being targeted at understanding its pathophysiology, its diagnosis, and its prognostic implications, in order to learn if it should be treated. Areas covered: A non-systematic review of the literature was developed using the Pubmed and Cochrane databases, focusing on randomized clinical trials and large observational studies that evaluated new physiopathological and epidemiological aspects, new clinical scenarios in which it has been assessed and its association with dementia. Finally, those studies that proposed new possible treatments were reviewed. Expert commentary: Interatrial block is not only a predictor of supraventricular arrhythmias, is a subclinical disease that might be considered as a marker of risk for adverse outcomes. Although there is some evidence to suggest that early treatment may be beneficial, potential therapies have yet to be investigated. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Box isolation of fibrotic areas (BIFA) is a promising ablation approach for atrial fibrillation (AF) patients. However, complete isolation of fibrotic anteroseptal left atrial area, where Bachmann's bundle is blending into the left atrial myocardium, is very specific and complex. Methods and results: In 34 AF patients with anteroseptal fibrosis, circumferential BIFA was performed in addition to pulmonary vein isolation. In 8 of 34 patients, complete isolation of the fibrotic area was achieved with BIFA alone. In 26 of 34 patients, a decrease in voltage amplitude with or without conduction delay was observed after box ablation but no complete isolation. Activation mapping and characteristic unipolar potentials revealed earliest activation inside the box from one (73%), two (15%), or three (12%) remaining inputs, in the region of Bachmann's bundle insertion. Focal ablation inside the box (mean radiofrequency impulses: 1.7 ± 0.4, mean radiofrequency time: 70 ± 19 seconds) led to complete isolation of the fibrotic area in 25 of 26 patients. Overall, 97% of anteroseptal boxes were completely isolated with additional focal ablation in the study group compared to 21% in the control group with BIFA alone (33/34 vs. 7/34, P < 0.001). Time of left atrial activation decreased significantly by 25% after complete box isolation (P < 0.001). After a single procedure, 12‐month arrhythmia‐free survival was 82% with additional focal ablation compared to 71% in the control group (P = 0.2). Conclusion: Targeted and focal ablation in the region of Bachmann's bundle is a novel and feasible technique to achieve complete isolation of the left atrial anteroseptal fibrotic area. [ABSTRACT FROM AUTHOR]

Pacing from the right atrial appendage (RAA) prolongs the P wave duration and can induce interatrial and especially left-sided atrio-ventricular dyssynchrony. Pacing from Bachmann's bundle closely reproduces normal physiology and has the potential to avoid the electromechanical dysfunction associated with conventional RAA pacing. Interatrial conduction delay is associated with an increased risk of stroke, heart failure, and death. In addition to a reduction in atrial fibrillation, Bachmann's bundle pacing has emerging applications as a hemodynamic pacing modality. This review outlines the pathophysiology of atrial conduction disturbances and their potential remedies and provides the reader with a practical guide to implementing Bachmann's bundle pacing with an emphasis on the recapitulation of normal electrical and mechanical function., Competing Interests: Conflict of interest: E.M.C.: speaking and teaching, Medtronic. C.W.I.: speaking and teaching, Abbott, Biotronik, Boston Scientific, Medtronic, Microport., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

The article presents the case of a 65-year-old male who was rushed to a hospital due to radiofrequency ablation of a redo postatrial fibrillation (AF) atrial tachycardia. His medical history included three endocardial ablation procedures due to persistent AF/atrial tachycardia (AT) including pulmonary vein (PV) isolation, cavotricuspid and mitral isthmus lines, and anterior wall. He was eventually diagnosed with AT showing centrifugal activation.

Recently, the Bachmann's bundle (BB) has been examined in connection with atrial fibrillation. However, the morphological properties of the BB remain to be clarified. In this study, the BB in hearts of monkeys and sheep was investigated by immunohistochemistry, scanning (SEM) and transmission (TEM) electron microscopy. Immuno-histochemically, BB myocytes showed a strong positive reaction for desmin antibody and that connexin (Cx) 40 and Cx43 were distributed at the intercalated disks. BB myocytes were characterized by a dense network of intermediate filaments which enveloped nucleus, myofibrils and mitochondria, respectively. The intercalated disks showed an irregular stair-like profile. Microprojections on the steps were smaller in number and larger in size than those in auricular myocytes. In conclusion, BB myocytes were different ultrastructurally from auricular myocytes, showing morphological properties of the conduction system.

Bradycardia, atrial stretch and dilatation, autonomic nervous system disorders, and the presence of triggers such as atrial premature contractions, are factors which predispose a person to paroxysmal AF. Atrial pacing not only eliminates bradycardia but also prevents atrial premature contractions and dispersion of refractoriness, which are a substrate for atrial fibrillation. As the prolonged duration of atrial activation during pacing, especially from locations changing the physiological pattern of this activation (right atrium lateral wall, right atrium appendage), negatively influences both a mechanical and an electrical function of the atria, the atrial pacing site affects an atrial arrhythmogenesis. A conventional atrial lead location in the right atrium appendage causes non-physiological activation propagation, resulting in a prolongation of the activation time of both atria. This location is optimal according to a passive fixation of the atrial lead but the available contemporary active fixation leads could potentially be located in any area of the atrium. There is growing evidence of the benefit of pacing, imitating the physiological propagation of impulses within the atria. It seems that the Bachmann's bundle pacing is the best pacing site within the atria, not only positively influencing the atrial mechanical function but also best fulfilling the so-called atrial resynchronization function, in particular in patients with interatrial conduction delay. It can be effectively achieved using only one atrial electrode, and the slight shortening of atrioventricular conduction provides an additional benefit of this atrial pacing site. [ABSTRACT FROM AUTHOR]

Background: The left atrial appendage (LAA) can be a source of atrial fibrillation (AF) triggering or a part of reentry. We sought to determine the characteristics and clinical outcomes of patients with LAA potential delay including electrical isolation (LAAEI) following LA anterior wall (LAAW) ablation for AF.Methods: LAAW ablation cases were collected from among 846 patients who underwent catheter ablation (CA). A total of 89 patients were enrolled; they were divided into three groups according to the extent of LAA potential injury. The ejection fractions (EFs) of the LAA and LA were measured by means of LA angiograms.Results: The mean age of all patients was 56.2 ± 10.7 years (74 males, 83 %). In 47 of the 89 patients, an LAA potential delay was identified after LAAW ablation (group 2). LAAEI was seen in 18 patients (group 3). In the remaining 24 patients, there was no LAA potential delay or LAAEI (group 1). The mean EF decreased significantly after CA in group 3 (P < 0.001). At 21-month follow-up, three patients (17 %) in group 3 had recurrence compared with 11 (42 %) in group 2 and 12 (46 %) in group 3 (P = 0.028). In multivariate analysis, diabetes mellitus and LAA potential delay were independent predictors of AF recurrence (P = 0.021, P = 0.008, respectively).Conclusion: Ablation of the LA anterior wall near the insertion of Bachmann's bundle and the neck of the LAA resulting in LAA potential delay or electrical isolation is effective in preventing recurrence of atrial fibrillation. [ABSTRACT FROM AUTHOR]