Case Report: A giant right atrial appendage aneurysm in a child.

Right atrial appendage aneurysm is an extremely rare cardiac anomaly. With unclear etiology, there is still no standard treatment method. Clinical symptoms and complications are important indicators for surgical resection. A 2-year-old boy without obvious cardiac symptoms was diagnosed with a giant right atrial outpouching arising from the right atrial appendage by computed tomography. The right atrial outpouching measured approximately 95 × 43 mm. Due to its large size and potential impact on function of right atrium and ventricle, the aneurysm was resected in surgery. During the surgery a 105 × 55 mm noncontractile cystic structure was found locating on the right anterior side of the right atrium. No other abnormalities like intracavity thrombus were detected. The patient was discharged five days after surgery. Postoperative recovery was uneventful.

Accumulated ß-catenin is associated with human atrial fibrosis and atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with increased risk of stroke and mortality. It has been reported that the process of atrial fibrosis was regulated by ß-catenin in rats with AF. However, pathophysiological mechanisms of this process in human with AF remain unclear. This study aims to investigate the possible mechanisms of ß-catenin in participating in the atrial fibrosis using human right atrial appendage (hRAA) tissues . METHODS: We compared the difference of ß-catenin expression in hRAA tissues between the patients with AF and sinus rhythm (SR). The possible function of ß-catenin in the development of AF was also explored in mice and primary cells. RESULTS: Firstly, the space between the membrane of the gap junctions of cardiomyocytes was wider in the AF group. Secondly, the expression of the gap junction function related proteins, Connexin40 and Connexin43, was decreased, while the expression of ß-catenin and its binding partner E-cadherin was increased in hRAA and cardiomyocytes of the AF group. Thirdly, ß-catenin colocalized with E-cadherin on the plasma membrane of cardiomyocytes in the SR group, while they were dissociated and accumulated intracellularly in the AF group. Furthermore, the expression of glycogen synthase kinase 3ß (GSK-3ß) and Adenomatous Polyposis Coli (APC), which participated in the degradation of ß-catenin, was decreased in hRAA tissues and cardiomyocytes of the AF group. Finally, the development of atrial fibrosis and AF were proved to be prevented after inhibiting ß-catenin expression in the AF model mice. CONCLUSIONS: Based on human atrial pathological and molecular analyses, our findings provided evidence that ß-catenin was associated with atrial fibrosis and AF progression.

Short-term safety and feasibility of a practical approach to combined atrial and ventricular physiological pacing: An initial single-center experience.

Background: Traditional right atrial appendage (RAA) pacing accentuates conduction disturbances as opposed to Bachmann bundle pacing (BBP). Objective: The purpose of this study was to evaluate the feasibility, efficacy, and safety of routine anatomically guided high right atrial septal (HRAS) pacing with activation of Bachmann bundle combined with routine left bundle branch area pacing (LBBAP). Methods: This retrospective single-center study included 96 consecutive patients who underwent 1 of 2 strategies: physiological pacing (PP) (n = 32) with HRAS and LBBAP leads and conventional pacing (CP) (n = 64) with traditional RAA and right ventricular apical leads. Baseline characteristics, sensing, pacing thresholds, and impedances were recorded at implantation and follow-up. Results: The PP and CP cohorts were of similar age (74.2 ± 13.8 years vs 73.9 ± 9.9 years) and sex (28.1% vs 40.6% female). There were no differences in procedural time (95.0 ± 31.4 minutes vs 86.5 ± 33.3 minutes; P = .19) or fluoroscopy time (12.1 ± 4.5 minutes vs 12.3 ± 13.5 minutes; P = .89) between cohorts. After excluding patients who received >2 leads, these parameters became significantly shorter in the CP cohort. The PP cohort exhibited higher atrial pacing thresholds (1.5 ± 1.1 mV vs 0.8 ± 0.3 mV; P <.001) and lower p waves (1.8 ± 0.8 mV vs 3.8 ± 2.3 mV; P <.001) at implantation and at follow-up. In the PP cohort, 72% of implants met criteria for BBP; of the ventricular leads, 94% demonstrated evidence of LBBAP. One lead-related complication occurred in each cohort. Conclusion: Routine placement of leads in the HRAS is a feasible and safe alternative to standard RAA pacing, allowing for BBP in 72% of patients. HRAS pacing can be combined with LBBAP as a routine strategy.

Leadless pacemaker implementation at the right atrial appendage apex: An initial preclinical assessment.

OBJECTIVE: This study evaluates the feasibility and efficacy of implanting a leadless pacemaker at the right atrial appendage (RAA) in a preclinical minipig model, aiming to address the limitations of atrial pacing with current leadless devices like the Medtronic Micra, which is typically used for right ventricular implantation. METHODS: Four minipigs, each with a median body weight of 45.8 ± 10.0 kg, underwent placement of the Micra transcatheter pacing system (TPS) via the right femoral vein into the RAA apex. The pacing performance was assessed over 1-week (short-term) and 3-month (long-term) periods. OUTCOMES: The initial findings indicated successful implantation, with satisfactory intrinsic R-wave amplitudes and pacing threshold. In the following period, the sensitivity, threshold, and impedance were stable with time. Notably, upon explanation at 3 months, a deep myocardial penetration by the device was observed, necessitating a redesign for safe long-term use in a growing subject's heart. CONCLUSION: While initial results suggest that RAA apex placement of the Micra TPS is promising for potential inclusion in a dual-chamber pacing system, the issue of myocardial penetration highlights the need for device redesign to ensure safety and effectiveness in long-term applications.

Successful management of fatal cardiac tamponade resulting from intravascular intervention for central vein occlusion in hemodialysis patients: A case report.

This case report highlights the successful management of fatal cardiac tamponade caused by intravascular intervention for central vein occlusion in hemodialysis patients. Prompt diagnosis and treatment are essential for patient prognosis in such cases. We present a case involving a challenging surgical procedure to address multiple complications, emphasizing the importance of early detection and appropriate interventions. The patient, who had a history of long-term central venous catheter use for hemodialysis, was diagnosed with central vein stenosis in addition to superior vena cava occlusion, hemodialysis catheter rupture, hypertension, and end-stage renal disease. Urgent ultrasound examination during surgery revealed pericardial effusion, prompting immediate pericardial drainage for stabilization. To overcome the complex challenges, we successfully performed an innominate vein-right atrial appendage bypass to restore vascular access and salvage the patient's life. The timely use of echocardiography for diagnosis and pericardial drainage contributed to stabilizing the patient's vital signs, providing an opportunity for subsequent surgical intervention. The innominate vein-right atrial appendage bypass procedure successfully relieved central vein stenosis and saved the patient's life. Although this surgical technique is not widely documented in hemodialysis patients with central venous involvement, it show cases the potential benefits for clinicians managing vascular access in this patient population. This case report underscores the need for awareness among clinicians regarding the risk of cardiac tamponade associated with intravascular intervention for central vein stenosis in hemodialysis patients. Minimizing central venous catheterization and prioritizing autogenous arteriovenous fistulas are crucial principles in preparing vascular access for hemodialysis patients. Early detection, timely interventions, and consideration of alternative surgical techniques can improve outcomes and prevent life-threatening complications.

A rare case of an unexpected trigger of paroxysmal atrial fibrillation in the right atrial appendage diverticulum.

INTRODUCTION: We described a rare case of an adolescent girl with paroxysmal atrial fibrillation originating from the right atrial appendage diverticulum and successfully converted to sinus rhythm after surgical intervention. METHODS: A 19-year-old girl was referred to the hospital for a catheter ablation of paroxysmal atrial fibrillation. conventional radiofrequency ablation using 3-D mapping were ineffective. Activation mapping showed the root of the free wall atrial appendage was first excited and catheter modeling (3D Carto map) showed a sac-like structure. RESULTS: We did selective angiography and further Computed tomography angiography (CTA) and Transesophageal echocardiography (TEE) which showed diverticulum originating from the right atrial appendage. Hence the patient was referred to cardiac surgery and had no recurrent atrial fibrillation at three months postoperative follow up. CONCLUSIONS: Right atrial appendage diverticulum was an extremely rare malformation that can coexist with atrial tachyarrhythmia. Surgical ligation or excision of the abnormal structure with local ablation can achieve excellent results.

Alternative atrial pacing site to improve cardiac function: focus on Bachmann's bundle pacing.

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.

Multivessel Coronary Artery Disease Complicated by Diabetes Mellitus Has a Relatively Small Effect on Endothelial and Lipoprotein Lipases Expression in the Human Atrial Myocardium and Coronary Perivascular Adipose Tissue.

Endothelial (EL) and lipoprotein (LPL) lipases are enzymes involved in lipoproteins metabolism and formation of atherosclerosis, a pathological feature of coronary artery disease (CAD). This paper examines the role of the lipases in the right atrial appendage (RAA) and coronary perivascular adipose tissue (PVAT) of patients with CAD alone or with accompanying diabetes. Additionally, correlation analysis for plasma concentration of the lipases, apolipoproteins (ApoA-ApoJ) and blood lipids (Chol, HDL-C, LDL-C, TAG) was performed. We observed that CAD had little effect on the lipases gene/protein levels in the RAA, while their transcript content was elevated in the PVAT of diabetic CAD patients. Interestingly, the RAA was characterized by higher expression of EL/LPL (EL: +1-fold for mRNA, +5-fold for protein; LPL: +2.8-fold for mRNA, +12-fold for protein) compared to PVAT. Furthermore, ApoA1 plasma concentration was decreased, whereas ApoC1 and ApoH were increased in the patients with CAD and/or diabetes. The concentrations of ApoC3 and ApoD were strongly positively correlated with TAG content in the blood, and the same was true for ApoB with respect to LDL-C and total cholesterol. Although plasma concentrations of EL/LPL were elevated in the patients with diabetes, CAD alone had little effect on blood, myocardial and perivascular fat expression of the lipases.

Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation.

BACKGROUND: Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known. OBJECTIVES: We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human. METHODS AND RESULTS: Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery. CONCLUSIONS: Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

Association of quantitative computed tomography-based right atrial appendage and right atrium parameters with postradiofrequency ablation recurrence of atrial fibrillation.

Background: The significance of the right atrial appendage (RAA) and right atrium (RA) in the recurrence of atrial fibrillation (AF) after radiofrequency ablation (RFA) remains uncertain. This retrospective case-control study aimed to quantitatively evaluate the role of morphological parameters of the RAA and RA in the recurrence of AF after RFA based on 256-slice spiral computed tomography (CT). Methods: A total of 297 patients with AF who underwent RFA for the first time between January 1 and October 31, 2020, were enrolled in the study, and they were divided into a nonrecurrence group (n=214) and a recurrence group (n=83). The volume of the RA, RAA and left atrium (LA); height of the RAA; long and short diameter, perimeter, and area of the RAA base; right atrial anteroposterior diameter; tricuspid annulus diameter; crista terminalis thickness; and cavotricuspid isthmus (CVTI) were measured, and the clinical data of patients were collected. Results: (I) Multivariable logistic regression analysis followed by univariable logistic regression analysis showed that the height of the RAA [odds ratio (OR) =1.124; 95% confidence interval (CI): 1.024-1.233; P=0.014], short diameter of the RAA base (OR =1.247; 95% CI: 1.118-1.391; P=0.001), crista terminalis thickness (OR =1.594; 95% CI: 1.052-2.415; P=0.028) and duration of AF (OR =1.009; 95% CI: 1.003-1.016; P=0.006) were independent predictors of postradiofrequency ablation AF recurrence. (II) Receiver operating characteristic (ROC) curve analysis showed that the prediction model constructed according to the multivariate logistic regression analysis presented good accuracy [area under the curve (AUC) =0.840; P=0.001]. A short diameter of the RAA base >26.95 mm had the highest predictive value for AF recurrence, with a sensitivity of 0.614 and a specificity of 0.822 (AUC =0.786, P=0.001). Pearson correlation analysis showed that there was a significant correlation between right atrial volume and left atrial volume (r=0.720, P<0.001). Conclusions: A significant increase in diameter and volume of the RAA and RA and tricuspid annulus diameter may correlate with postradiofrequency ablation AF recurrence. The height of the RAA, short diameter of the RAA base, crista terminalis thickness, and AF duration were independent predictors of recurrence. Among them, the short diameter of the RAA base had the highest predictive value for recurrence.

Regions of Highly Recurrent Electrogram Morphology With Low Cycle Length Reflect Substrate for Atrial Fibrillation.

Traditional anatomically guided ablation and attempts to perform electrogram-guided atrial fibrillation (AF) ablation (CFAE, DF, and FIRM) have not been shown to be sufficient treatment for persistent AF. Using biatrial high-density electrophysiologic mapping in a canine rapid atrial pacing model of AF, we systematically investigated the relationship of electrogram morphology recurrence (EMR) (Rec% and CLR) with established AF electrogram parameters and tissue characteristics. Rec% correlates with stability of rotational activity and with the spatial distribution of parasympathetic nerve fibers. These results have indicated that EMR may therefore be a viable therapeutic target in persistent AF.

Right Atrial Appendage Thrombus in a Patient Undergoing Thoracoscopic Left Atrial Appendectomy for Atrial Fibrillation.

Left atrial appendage (LAA) closure may prevent atrial fibrillation (AF)-induced thromboembolism. We describe a rare case of right atrial (RA) thrombus after thoracoscopic left atrial appendectomy and pulmonary vein isolation. Careful evaluation for the presence of RA thrombus in patients with persistent AF after LAA occlusion may be necessary. (Level of Difficulty: Intermediate.).

Right atrial appendage firing in atrial fibrillation.

Background: The role of atrial fibrillation (AF) drivers located at the left atrium, superior vena cava, crista terminalis and coronary sinus (CS) is well established. While these regions are classically targeted during catheter ablation, the role of right atrial appendage (RAA) drivers has been incompletely investigated. Objective: To determine the prevalence and electrophysiological characteristics of AF driver's arising from the RAA. Materials and methods: We conducted a retrospective analysis of clinical and procedural data of 317 consecutive patients who underwent an AF ablation procedure after bi-atrial mapping (multipolar catheter). We selected patients who presented with a per-procedural RAA firing (RAAF). RAAF was defined as the recording of a sustained RAA EGM with a cycle length shorter than 120 ms or 120 < RAAF CL ≤ 130 ms and ratio RAA CL/CS CL ≤ 0.75. Results: Right atrial/atrium appendage firing was found in 22 patients. The prevalence was estimated at 7% (95% CI, 4-10). These patients were mostly men (72%), median age: 66 yo ± 8 without structural heart disease (77%). RAAFs were predominantly found in paroxysmal AF patients (63%, 32%, and 5% for paroxysmal, short standing and long-standing AF, respectively, p > 0.05). RAAF median cycle length was 117 ms ± 7 while CS cycle length was 180 ms ± 10 (p < 0.01). Conclusion: In 317 consecutive AF ablation patients (22 patients, 7%) the presence of a high-voltage short-cycle-length right atrial appendage driver (RAAF) may conclusively be associated with AF termination. This case series exemplifies the not-so-uncommon role of the RAA in the perpetuation of AF.

A Gigantic Congenital Right Atrial Appendage Aneurysm in an Infant: Ten-Year Follow-Up.

A gigantic right atrial appendage aneurysm (RAAA) is a rare condition usually discovered during the third decade of life after being symptomatic. We present an asymptomatic RAAA discovered early during the basic screening of an infant and its natural history, and a ten-year follow-up due to its parents being against operation.

Atrial thrombosis: Not only left, think also about right!

Atrial fibrillation (AF) is the most common arrhythmia in the general population. Systemic thromboembolism from left atrial appendage (LAA) thrombosis is a well-known complication of AF, whereas thromboembolic complications from a right atrial (RA) thrombus are infrequent. Nevertheless, the prevalence of RA thrombosis is debated; despite having a low prevalence in echocardiographic studies, the higher prevalence found in autoptic studies rises the hypothesis of an under detection of RA clots, possibly related to the limited evaluation of right atrial appendage (RAA) with non-invasive imaging. Here we present a review of the current literature about RA thrombosis, regarding its diagnosis, differentials, and best treatment options.