Atrioventricular (AV) node ablation represents an established therapeutic option in the management of atrial fibrillation (AF) and other atrial tachyarrhythmias, particularly in patients with symptomatic tachycardia who remain unresponsive or intolerant to pharmacological therapy. The procedure is often considered in cases of refractory arrhythmias, antiarrhythmic drugs intolerance, or tachycardiomyopathy, and plays a key role in optimizing outcomes in patients undergoing cardiac resynchronization therapy, where achieving adequate biventricular pacing is otherwise compromised by rapid ventricular responses. Traditionally, AV node ablation is performed using radiofrequency energy delivered at the region of the His bundle, guided by the earliest His potential recordings. However, the anatomical complexity of the AV node and Koch’s triangle poses important challenges, including the risk of incomplete ablation, persistence of conduction, lack of reliable junctional escape rhythms, and increased risk of proarrhythmia. Recent advances in high-resolution mapping and electroanatomical guidance have enabled a more precise anatomical approach, selectively targeting the compact AV node while reducing collateral injury. These developments offer the potential for improved procedural safety, long-term efficacy, and a more standardized strategy for patient management. This review summarizes current evidence, techniques, and clinical implications of AV node ablation, highlighting its role in the evolving landscape of arrhythmia treatment.

Background:While sinus bradycardia and atrioventricular (AV) block in athletes have traditionally been viewed as benign consequences of enhanced vagal tone, recent evidence suggests that, in some individuals, nodal dysfunction may be intrinsic and potentially mediated by epigenetic mechanisms. Therefore, differentiating between these mechanisms is crucial for guiding appropriate clinical management.Methods:Among 550 elite athletes undergoing routine cardiovascular evaluation, 72 were referred for a transesophageal electrophysiological study (EPS): 58 with significant sinus bradycardia or suspected AV node dysfunction (cases) and 14 athletes with symptoms consistent with supraventricular tachyarrhythmias but no bradyarrhythmia (controls). All participants underwent an EPS to assess corrected sinus node recovery time (CSNRT) and AV nodal Wenckebach point. In the case group, 24 athletes exhibited abnormal parameters at baseline and underwent a repeat EPS following complete autonomic blockade with intravenous propranolol and atropine, aimed at suppressing extrinsic autonomic influences.Results:The corrected sinus node recovery time exceeded 550 ms in 18 (31%) cases, and the Wenckebach point was greater than 500 ms in 8 (14%) cases. In all eight athletes with baseline AV conduction abnormalities, they normalized after autonomic blockade, consistent with a functional vagal mechanism. In contrast, the mean sinus rate remained unchanged after autonomic blockade, and in 12/18 (67%) of the athletes with prolonged CSNRT, continued to exhibit abnormal values despite autonomic suppression, indicating a probable intrinsic origin. Control subjects showed normal EPS parameters.Conclusions:The EPS with a pharmacological autonomic blockade represents a useful approach for distinguishing extrinsic, functional bradycardia from intrinsic nodal disease in athletes. While AV node dysfunction appears exclusively vagally mediated and reversible, a subset of sinus node dysfunction cases may reflect early, possibly epigenetically driven, intrinsic alterations.

Significant lymphatic structural remodeling and dysfunction have been observed in preclinical models of cardiovascular disease. However, a detailed understanding of the normal structure and distribution of lymphatic vessels (LyVs) in the heart is still lacking. The goal of this study is to define the pattern of LyVs at various cardiac anatomical sites using Prox1-tdTomato lymphatic reporter mice. By light sheet microscopy, we first confirmed the presence of an extensive network of LyVs on the epicardial surface of the ventricles while minimal signal was detected on the atria. We then evaluated LyV distribution within the heart using cryo- and vibratome sections. To ensure accurate identification of Prox1-tdTomato+ LyVs, we performed immunostaining of common lymphatic markers (LYVE1, podoplanin and VEGFR3). In the ventricles, LyVs were enriched on the epicardium, subepicardial region and endocardium of the right ventricular septum. We also detected LyVs on the subepicardial surface of the left atrium, within the mitral valve and interatrial septum and near the valves and atrioventricular node (AVN). In addition to LyVs, LYVE1 and PROX1 were expressed by other cell types. LYVE1 was expressed by tissue resident macrophages and a subset of endocardial cells lining the trabeculated regions of the atria and ventricles, and PROX1 was mainly expressed by valvular endothelial cells, endocardial cells lining the interatrial septum and a subset of cells within the AVN. Lastly, scRNA-Seq analysis revealed six subtypes of cardiac lymphatic endothelial cells. Our study serves as a comprehensive resource to facilitate the proper identification of LyVs in the mouse heart.

Pulsed field ablation (PFA) is a novel, non-thermal technique for atrial fibrillation ablation that is currently under early investigation for paroxysmal supraventricular tachycardia (PSVT). We conducted a meta-analysis to evaluate the efficacy and safety of PFA in this setting. We systematically searched PubMed, Embase, Cochrane Central, and Web of Science for studies on PFA in PSVT, including atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) with concealed or manifest accessory pathways. Outcomes included acute ablation success, success at 1, 3, and 6months, and procedural/postoperative adverse events (AEs). Proportions were pooled using a random-effects model with arcsine transformation to account for extreme values. Analyses were conducted using R (v4.3.2). Five prospective single-arm studies involving 202 patients were included. The pooled acute success rate was 99.98% (95% CI: 99.29-100), with sustained success at 1, 3, and 6months. Procedural and postoperative AE rates were low: 0.92% (95% CI: 0.00-4.88) and 0.06% (95% CI: 0.00-0.87), respectively. Subgroup analysis showed 100% acute success in AVNRT and in AVRT with concealed pathways, with high sustained success at 6months. In AVRT with manifest pathways, acute success was 97.5% (95% CI: 84.74-100), maintained through follow-up. In this systematic review and meta-analysis, PFA demonstrated excellent safety and efficacy for the treatment of PSVT. Randomized controlled trials are warranted to establish the outcomes of PFA in this setting relative to thermal ablation.

Radiofrequency (RF) ablation has long been the standard treatment for atrioventricular nodal reentrant tachycardia (AVNRT) in children. However, cryoablation (CA) has gained popularity due to its safety profile and acceptable long-term success rates. Comparative data on different CA catheter tip sizes in pediatric AVNRT are limited. To compare the acute and long-term outcomes of 6-mm vs. 8-mm tip CA catheters in pediatric patients undergoing AVNRT ablation. This retrospective single-center study included 129 pediatric patients (76 female, mean age 13±3.0years, mean weight 51.7±15.7kg) who underwent CA for AVNRT between January 2016 and December 2022. A 6-mm tip catheter was used in 64 patients and an 8-mm tip catheter in 65 patients. All procedures were performed using a three-dimensional electroanatomical mapping system (EAMS) (EnSite, Abbott/St. Jude Medical Inc., St. Paul, MN, USA), with minimal or no fluoroscopy in most cases. Acute success, recurrence rates, procedural parameters, and complications were compared between groups. Of the 129 patients, 126 (97.7%) had typical AVNRT and 3 (2.3%) had atypical AVNRT. The mean procedure time was 151.9±43min, with no significant difference between groups. Acute success rates were 100% in the 6-mm group and 98.5% in the 8-mm group (p>0.05). The mean number of cryolesions was 8.5±2.3 (6-mm) and 9.0±2.5 (8-mm) (p>0.05). Over a mean follow-up of 31.4±26 months, recurrences occurred in six patients (4.6%), all successfully re-ablated. Long-term success rates were 94.4% overall, with no significant difference between groups. No permanent complications occurred; transient AV block was observed in one patient (0.7%). Both 6-mm and 8-mm CA catheters achieve high acute success and low recurrence rates in pediatric AVNRT with similar safety profiles. Catheter tip size can be tailored to patient age and weight without compromising efficacy. Minimal fluoroscopy approaches can be applied safely in the majority of cases.

Background: The atrioventricular node artery supplies the atrioventricular node (AVN) and exhibits variability in origin and course as it may originate from the right coronary artery, left coronary artery or both. While the AVN is typically located within Koch’s triangle, multiple studies have demonstrated significant variability in its precise location. These anatomical variations may have substantial implications for procedures that require accurate localization, such as atrioventricular nodal (AVN) ablation. Although right-sided AVN ablation is the standard approach, up to 18% of cases require conversion to a left-sided approach. This is often due to procedural challenges in achieving adequate AV nodal conduction block and may ultimately increase procedure duration and radiation exposure. The aim of this study is to investigate the role of coronary dominance in the procedural planning and approach of AVN ablation. Methods: In this retrospective study, we included 132 patients who underwent AV nodal ablation and had a coronary computed tomography angiography (CTA) at William Beaumont University Hospital (Royal Oak, MI) over a three year period. Coronary CTA was performed either prior to or following AVN ablation and reviewed to determine coronary dominance. Patients were grouped based on coronary dominance: Group 1 (right dominant, n=104) and Group 2 (left or co-dominant, n=28). Numeric values were presented as mean ± SD and a paired Student’s t -test was used to compare modalities; significance was set at p < 0.05. Results: Group 2 patients had significantly higher odds of requiring left-sided AVN ablation compared to those in Group 1(21.4% vs. 1.9%, p <0.001). Mean total procedure time was longer in Group 2 (50 vs. 34 minutes, p =0.044), with a non-significant trend toward increased fluoroscopy time (10.4 vs. 7.9 minutes, p =0.311) and radiation exposure (1980 vs. 1350 cGy*cm2, p =0.372). No procedural complications were recorded. Conclusion: Coronary dominance may influence the anatomical location of the AVN and subsequently, the access site and procedural approach for AVN ablation. To our knowledge, this is the first study to explore the relationship between coronary dominance and procedural approach for AVN ablation. While limited by retrospective design, small sample size and anatomical variations of the AV node, this study suggests pre-procedural imaging may have a role in procedural planning and approach, improving procedural efficiency and safety.

Background: Atrioventricular node (AVN) ablation combined with pacing is a well-established therapy for refractory atrial fibrillation. Traditional right ventricular pacing has been shown to cause ventricular dyssynchrony and may worsen atrial remodeling. Left bundle branch area pacing (LBBAP) provides a more physiological ventricular activation than non-conduction system pacing (non-CSP). However, the effects of LBBAP on left atrial (LA) remodeling and left ventricular (LV) function after AVN ablation in atrial fibrillation patients remain underexplored. We aimed to compare LA and LV functional outcomes between LBBAP and non-CSP in this population. Hypothesis: LBBAP preserves or improves LA and LV function compared to non-CSP in patients with atrial fibrillation following AVN ablation. Methods: We retrospectively identified patients with atrial fibrillation undergoing AVN ablation followed by either LBBAP or non-CSP (biventricular, leadless, or septal right ventricular pacing) between 2019 and 2023. Pre- and post-pacing echocardiograms were analyzed for LA volumes and emptying fraction, LA strain, LV global longitudinal strain (GLS), LV volumes and ejection fraction, and diastology parameters. Changes in these parameters were compared between groups using analysis of covariance, while accounting for baseline differences and clinical factors. Results: In the study group (n=73), 35 patients underwent LBBAP while 38 underwent non-CSP. Mean age was 79.3 years, and 74% were female. After a mean interval between pre- and post-pacing echocardiograms of 17.1 months, LBBAP was associated with greater adjusted improvement in LA reservoir strain (+3.9%, p=0.001), LA contractile strain (-2.1%, p=0.02), and LV GLS (-2.2%, p=0.02). LA volumes and volume indexes were also significantly lower in the LBBAP group compared to the non-CSP group, indicating improved LA unloading following LBBAP (Figure 1). Conclusion: LBBAP was associated with improved LA strain, LV GLS, and LA volumes compared to non-CSP in patients with atrial fibrillation undergoing AVN ablation and pacemaker implantation. These findings highlight the physiologic benefits of LBBP in improving both LA and LV function and further support LBBP as a preferred approach in patients undergoing AVN ablation.

Case Description: BRASH syndrome is characterized by the following: bradycardia, renal failure, atrioventricular blockade, shock, and hyperkalemia. Due to its overlapping features, it is often under-reported and misdiagnosed as isolated hyperkalemia. This case involves a 53-year-old male who presented with palpitations following a hemodialysis session. Upon arrival, the patient was tachycardic and found to be in atrial flutter (Figure 1). Initial treatment with diltiazem effectively controlled his heart rate. However, the following day, the patient received additional beta-blockers and developed hypotension (72/50 mmHg), bradycardia (39 bpm) (Figure 2), and hyperkalemia (K 7.3). Upon being upgraded to the cardiac care unit (CCU), his management included atropine, epinephrine, glucagon, and calcium gluconate. Ultimately, the patient was stabilized with urgent dialysis. Discussion: BRASH syndrome is a cyclical condition that includes the amalgamation of the following: bradycardia, renal failure, atrioventricular (AV) nodal blockade, shock, and hyperkalemia. Carries an in-hospital mortality of 5.7%. It is often underreported and mistaken for isolated hyperkalemia or AV blocker toxicity. One reason for this underreporting is the subtlety of its presentation, which can easily be confused with hyperkalemia alone, especially when patients present primarily with bradycardia and renal dysfunction. Unlike typical hyperkalemia, which generally needs to be severe to induce bradycardia, BRASH syndrome can cause significant bradycardia even with moderate potassium elevations due to the synergistic effect of AV nodal blockers and renal failure. This case of BRASH syndrome, triggered by both beta-blockers and calcium channel blockers, is rare. The combined use of both agents compounds the effects on AV node conduction and can severely depress heart rate, especially when renal impairment leads to reduced drug clearance. Management of BRASH syndrome requires addressing all components of the syndrome. Initial treatment often includes correction of hyperkalemia with calcium gluconate and insulin. Bradycardia may be managed with atropine, epinephrine, or pacing. Additionally, medications contributing to AV node blockade should be held, and hemodynamic support with vasopressors may be necessary if hypotension persists. In some cases, such as ours, dialysis may be required to manage hyperkalemia and improve renal clearance of medications.

Background: Persistent left superior vena cava (PLSVC) is a rare congenital venous anomaly that can complicate the anatomy of the right atrium and coronary sinus, posing technical challenges during catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT). Optimal ablation strategies in this subset remain poorly defined. Methods: We retrospectively analysed 11 patients with PLSVC who underwent typical AVNRT ablation at our centre between 2015 and 2024, identified from a cohort of 2,030 ablations (0.54%). PLSVC was suspected by dilated coronary sinus on transthoracic echocardiogram and confirmed by coronary sinus catheter manipulation or coronary sinus venography. All procedures were performed using the Claris EP Workmate system with right femoral vein access. Due to unstable His catheter positioning from distorted anatomy, fluoroscopic landmarks in the left anterior oblique (LAO 30°) view were used in review screen during radiofrequency ablation. Radiofrequency ablation (RFA) was delivered using a 4-mm non-irrigated Blazer™ catheter (max 40W, 60°C) targeting the slow pathway, guided either by low-amplitude electrograms or anatomical landmarks—primarily the anterior lip of the mid coronary sinus ostium (CSOS). A long sheath (SR0) was used in 5 patients for better catheter stability. Results: The mean age was 38 ± 11 years; 8 were female. Typical AVNRT was inducible in all 11 patients. Immediate procedural success was achieved in 100%, defined by non-inducibility of AVNRT post-ablation with and without isoproterenol. Junctional ectopy during energy delivery was used as a surrogate marker when slow pathway potentials were absent (8/11 patients). Long-term success at 24-month follow-up was 91%, with one recurrence. There were no major complications. In 3 patients, the slow pathway was localized to the posteroinferior septum; in the remainder, ablation was successful within the coronary sinus ostium. Conclusion: In patients with PLSVC, right-sided ablation of typical AVNRT remains effective, despite anatomical distortion. Atypical anterior ablation targets mostly within the Coronary sinus ostium, fluoroscopic guidance, and long sheath support facilitate successful outcomes. Awareness of these adaptations may reduce recurrence and procedural risk in this challenging subset.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common form of supraventricular tachycardia (SVT) in childhood resulting from dual AV nodal physiology (DAVNP) substrate. Children with AVNRT present with episodic chest discomfort or palpitations. The baseline electrocardiogram (ECG) in children with AVNRT appears normal. The ability to identify AVNRT risk from a baseline ECG may help during evaluation of children for palpitations with otherwise normal ECG. Hypothesis: We hypothesized that machine learning (ML) algorithms would be able to identify subtle ECG markers of DAVNP substrate on baseline ECG. Methods: Retrospective single center case-control study from 2020 to 2025, including 12 lead ECG data from children 5-18 years of age who had a confirmed diagnosis of AVNRT through electrophysiological study. Patients with congenital heart disease were excluded. The control group consisted of children 5-18 years presenting to clinic for chest pain or palpitations and had normal cardiac findings. ECGs were processed to extract 12×65 biomarkers. Preprocessing included normalization, handling categorical and missing values. SMOTE was used during training to prevent bias. The dataset was split into 70% train, 15% validation, and 15% test. Both 1D and 2D lead data were assessed during model building. The models included 1 dimensional and 2 dimensional convolutional neural networks (CNN), Support Vector Machines (SVM), K-Nearest Neighbors (KNN), Logistic Regression, and Boosting techniques. We implemented 10 ML models for 1D data: 9 traditional and a 1D CNN and used 2D CNNs for 2D data. Three ensemble models were also built using majority voting from the top performers. Optimal hyperparameters were determined using Bayesian optimization integrated with a grid search approach on the train/validation and evaluated on the test set. We used AUC, accuracy, sensitivity, and specificity to evaluate performance and compared the best models for statistical significance. Results: The case group included 170 children, control group included 93. Models using individual leads aVRL, V1, and V4 showed promising results with AUC as high as 0.85. Consistent improvement is observed by using ensemble models combining three leads in both traditional ML and CNN approaches, with AUC reaching 0.95 and maintaining balanced sensitivity and specificity of 0.85 each. Conclusion: ML algorithms can successfully identify subtle findings of DAVNP on baseline ECG that predict AVNRT risk.

Introduction: Management of tachyarrhythmias during pregnancy, particularly atrioventricular nodal reentrant tachycardia (AVNRT), presents unique challenges due to concerns regarding maternal and fetal safety. Electrical cardioversion poses risks such as fetal distress and preterm labor, while pharmacologic therapies must be cautiously administered to avoid potential fetal harm. Intravenous adenosine remains first-line therapy, however, experience with doses exceeding 12 mg during pregnancy is limited. We present a case demonstrating that administration of high-dose adenosine (24 mg) can safely and effectively enhance subsequent beta-blocker efficacy in termination of refractory AVNRT during late-term pregnancy. Case: A 29-year-old woman at 37 weeks of gestation presented with sustained narrow-complex tachycardia (~180 bpm) consistent with AVNRT, accompanied by palpitations and lightheadedness. Initial heart rate was ~187 bpm with blood pressure of 105/83 mmHg. Labs, including electrolytes and cardiac biomarkers, were normal. ECG confirmed AVNRT with retrograde P-waves. Methods: Initial management with vagal maneuvers and intravenous metoprolol (two doses of 2.5 mg) failed to convert the AVNRT and resulted in transient hypotension (BP ~85/60 mmHg). Intravenous adenosine was then administered in escalating doses (6, 12, 18, and 24 mg) under continuous maternal and fetal monitoring. While high-dose adenosine administration produced transient AV block and slowed the heart rate, sustained conversion was not achieved. A subsequent IV dose of metoprolol (5 mg) was given immediately thereafter. Results: Immediately following administration of metoprolol, the tachycardia terminated and sinus rhythm was immediately restored (HR ~103 bpm). Blood pressure promptly stabilized, fetal monitoring remained reassuring. Post-conversion echocardiogram revealed normal cardiac structure and function (EF 60–65%). Patient’s hospitalization and delivery were uncomplicated. Discussion: High-dose adenosine administration up to 24 mg was safely tolerated during late-term pregnancy and significantly enhanced the effectiveness of subsequent beta-blocker therapy in refractory AVNRT. Adenosine's transient AV nodal suppression likely conditioned the reentrant circuit, facilitating effective termination with beta-blocker therapy. This sequential pharmacologic strategy is a valuable pharmacologic alternative to terminate AVNRT in late-term pregnancy and avoid electrical cardioversion.

Introduction: Catheter ablation for atrioventricular nodal reentrant tachycardia (AVNRT) traditionally used a combination of anatomic and signal morphology mapping. Newer advanced mapping techniques (AMTs) for AVNRT include propagation mapping to identify the collision point of atrial wavefronts and voltage mapping to identify a low-voltage bridge. Due to very good outcomes of AVNRT ablation in general, assessment of the true value of AMTs is challenging. Hypothesis: AMTs improve procedural outcomes in pediatric patients and are viewed as valuable (both accurate and helpful). Aims: To describe outcomes for AVNRT ablations in pediatric patients with and without use of AMTs and to assess intraprocedural views on their value. Methods: Single-center retrospective study. Our center began almost exclusively using AMTs in AVNRT ablations in 2020, with both propagation and voltage mapping performed in these cases (AMT group: 2020-2024). A control group included the same number of the most-recent, consecutive, non-AMT procedures (2017-2022). Procedural outcomes were compared. In addition, the accuracy of AMT (whether combined pre-ablation AMTs correctly predicted the successful ablation location) and perceived helpfulness of AMT (as documented by the electrophysiologist at the time of the procedure) were assessed. Results: 99 AMT procedures and 99 controls were compared. Table 1 shows baseline characteristics while Table 2 shows procedural outcomes. There were no statistically significant differences in success rates or recurrences. Both the number and total time of RF and cryoablation lesions were greater in the AMT group. Median fluoroscopy time (9.9 v 13.8 min) and dose (1914 vs 4073 mGy-cm2) were lower in AMT procedures, but procedures lasted longer (133 v 109 min). AMTs were accurate in 52% of cases. When accurate, degree of helpfulness of AMT was categorized into three categories: 1.) helped identify the correct ablation location not suggested by traditional techniques in 23%; 2.) helpful but identified the same location as from traditional mapping in 17%, and 3.) unclear helpfulness in 11%. Conclusion: Only 52% of AMT localizations were viewed as accurate, but 23% were viewed as clearly helpful beyond traditional mapping techniques. AMTs correlated with reduced fluoroscopy but longer procedure times. The total number of ablation lesions and ablation times were higher in the AMT group and suggests that AMTs may adversely influence initial ablation locations.

Introduction: Sarcomatoid carcinoma is an aggressive, poorly differentiated malignancy with both epithelial and mesenchymal features. While previously described in the lungs, kidneys, and soft tissues, no cases have been documented with a primary origin in the pericardium. Its diagnostic ambiguity and aggressive course present significant challenges. We present the first reported case of primary sarcomatoid carcinoma of the pericardium. Case Description: An 81-year-old male with multiple comorbidities including hypertension, atrial fibrillation, bioprosthetic aortic valve replacement (2022), Crohn's disease, and HFmrEF presented with gastrointestinal symptoms. CT abdomen incidentally revealed a large pericardial mass (10×7 cm) compressing the left atrium and basal left ventricle, causing severe mitral stenosis (mean gradient 15 mmHg). Initial differential included mesothelioma and metastatic pulmonary sarcomatoid carcinoma. The patient underwent 10 sessions of palliative radiation. Post-radiation, he developed worsening nausea, vomiting, dysphagia, atrial fibrillation with RVR, and pleural effusions. Cardiac imaging (MRI [Figure 1] and PET [Figure 2]) confirmed the pericardial mass with compression effects and no distant metastases. Thoracentesis and supportive care provided temporary relief. Pericardial FNA pathology revealed a biphasic keratin-positive malignant neoplasm consistent with sarcomatoid carcinoma. Immunohistochemistry was positive for AE1/AE3, CK7, vimentin, and OSCAR. Negative markers ruled out mesothelioma, RCC, melanoma, and other sarcomas. Despite multidisciplinary input, the mass was inoperable. Planned AV nodal ablation and Micra pacemaker were deferred due to anesthetic risk. Inpatient chemotherapy (carboplatin + pemetrexed) was planned, but the patient decompensated before initiation. Discussion: Sarcomatoid carcinoma of pericardial origin is undocumented. PET/CT imaging and immunohistochemistry were key to diagnosis. Tumor compression mimicked valvular and heart failure symptoms, complicating management. Despite early multidisciplinary care, prognosis was poor due to rapid clinical decline. Conclusion: This case highlights the importance of early recognition, tissue diagnosis, and aggressive multidisciplinary planning in rare cardiac malignancies. Sarcomatoid carcinoma should be considered in the differential diagnosis of atypical pericardial masses. Further literature and registry data are needed to guide future management.

Introduction: Bradycardia, Renal failure, Atrioventricular (AV) nodal blockade, Shock, and Hyperkalemia (BRASH) syndrome is a rare reversible clinical condition that can be life-threatening through a vicious cycle of bradycardia, exacerbated by AV nodal blocking agent use, hyperkalemia and renal failure. We report a case that was refractory to vasopressor treatment, medical therapy and transvenous pacemaker for which a permanent pacemaker was needed. Case Presentation: We report a 64-year-old female patient with a medical history of Chronic Kidney Disease Stage IIIb, Diabetes Mellitus Type II, Hypertension and coronary artery disease with multiple coronary artery bypass grafts (CABG), who presented to the emergency department complaining of dizziness and lightheadedness for the past 12 hours. Upon presentation, patient was hypotensive, bradycardic, hyperkalemic and with acute kidney injury, raising suspicion of BRASH syndrome. Treatment resolved the patient’s condition except the bradycardia which eventually needed a permanent pacemaker insertion. Bradycardia in BRASH syndrome, an already rare condition, necessitating permanent pacemaker insertion, and not resolving by stopping amiodarone and metoprolol, is not commonly reported. Discussion: AVNB agent, amiodarone and metoprolol, caused bradycardia which decreased cardiac output and renal blood flow. The subsequent acute kidney injury led to decreased clearance of metoprolol, amiodarone and worsening hyperkalemia. This has resulted in a further decrease in cardiac output which has put the patient in a continuous vicious cycle until she reached cardiogenic shock. Hence, rapid diagnosis and correct management with medical therapy, vasopressors and temporary pacemaker is necessary to reverse and stop the cycle. Nevertheless, a non resolving bradycardia may need a permanent pacemaker insertion as in our case.

Intermittent high-grade atrioventricular (AV) block is a rare bradyarrhythmia in the young. In the absence of structural conduction system disease, it may result from heightened vagal tone. We present a unique case of a young adult with coexisting incessant atrial tachycardia (AT) and high-grade AV block, both of which resolved following catheter ablation targeting the AT arising in the left atrial appendage (LAA). Description of Case: A 25-year-old obese male with a 10-year history of exertional fatigue, palpitations, and presumed sinus tachycardia was referred for evaluation. Baseline ECG showed AT at 103 bpm with negative P waves in I and aVL. Ambulatory monitoring for 13 days revealed frequent tachycardia to a max of 181, average 99 bpm, but also 277 episodes of high-grade AV block up to 3 nonconducted P waves, including daytime pauses up to 2.5 seconds. An electrophysiology study for symptomatic “near incessant” AT demonstrated a focal AT arising from the base of the LAA with epinephrine infusion. Radiofrequency ablation at this site (6 lesions) rendered the AT non-inducible. AV nodal function and His-Purkinje conduction were normal. Follow-up ECGs and 2 week monitors immediately and at 6 months post-ablation revealed inappropriate sinus tachycardia (IST), and no AT nor AV block. Discussion: This case illustrates a rare co-occurrence of focal LAA AT, intermittent high-grade AV block, and IST, for which LAA ablation targeting AT also eliminated AV block. Whether all the findings are linked due to an autonomic mechanism or whether the AT was serendipitously located near ganglionated plexi that were responsible for the AV block is uncertain. These findings support the emerging role of autonomic modulation with ablation in the management of high-grade AV block in the young.

Progressive Conduction System Disease in Hydroxychloroquine Cardiotoxicity: A Call for Early Vigilance.

Long RP supraventricular tachycardia poses a significant diagnostic challenge because of overlapping electrophysiological features among differential diagnoses. Detailed evaluation with an electrophysiological study is essential for accurate diagnosis and effective management, particularly when initial ablation attempts fail to eliminate inducibility. A 40-year-old Southeast Asian male with a 5-year history of recurrent palpitations was referred for evaluation. Baseline echocardiography was normal. During symptomatic episodes, electrocardiography demonstrated long RP tachycardia. Electrophysiology study revealed eccentric atrial activation with decremental conduction, with the earliest A recorded at DD9-10 (coronary sinus ostium/left posteroseptal region). Tachycardia cycle length was 410 ms, with a VA interval of 215 ms, AH interval of 93 ms, HA interval of 332 ms (AH/HA < 1), a VAV response during ventricular entrainment, PPI-TCL of 225 ms, and SA-VA of 194 ms. Ventricular reset did not terminate the arrhythmia and showed no atrial delay or advancement. Ablation at the coronary sinus ostium terminated the tachycardia but did not prevent reinduction. A subsequent slow pathway ablation was performed, during which slow junctional rhythm was observed. Post-ablation testing demonstrated crossover at 320ms, while supraventricular tachycardia remained easily inducible with atrial S1 pacing at 400ms. Given persistent inducibility, medical therapy was optimized and the patient was scheduled for advanced three-dimensional mapping and ablation. The leading differential diagnoses were atypical atrioventricular nodal reentrant tachycardia (fast-slow variant) with a bystander accessory pathway and permanent junctional reciprocating tachycardia with coexisting dual AV nodal physiology. This case illustrates the diagnostic complexity and management challenges of long RP supraventricular tachycardia, particularly in distinguishing atypical atrioventricular nodal reentrant tachycardia from permanent junctional reciprocating tachycardia. When initial ablation does not achieve full arrhythmia control, a stepwise strategy involving detailed electrophysiological evaluation, cautious ablation, and advanced mapping may be required to guide definitive therapy.

The safety and tolerability of early invasive therapies for rapid atrial fibrillation in patients with cardiogenic shock is yet to be established. This retrospective study reviewed patients with diagnosis of atrial fibrillation and cardiogenic shock during the same hospital admission between 2019 and 2024. These patients were dependent on inotropes and/or mechanical circulatory support and received PVI or AVJ ablation with CRT implantation during the index hospitalization. Outcomes measured were procedural complications, post-procedural heart failure or Afib hospitalization, continued inotrope and/or mechanical circulatory dependence, mortality, and change in ejection fraction. Of 54 patients reviewed, 16 met the study criteria. At baseline, 94% (15/16) of patients were on inotropes for management of cardiogenic shock while 44% (7/16) were on mechanical circulatory support. There were minimal adverse events associated with invasive management of atrial fibrillation. There was a trend towards reduced dependence on inotropes and mechanical support post-procedure. There was a significant increase in ejection fraction from a baseline of 20% pre-procedure to an average of 36% post-procedure, with an increase in EF recorded in 80% of patients. There was one re-admission for heart failure and no re-admissions for atrial fibrillation at 6 months post-procedure. Our study shows that among patients with atrial fibrillation and cardiogenic shock, invasive therapy with pulmonary vein isolation or AV node ablation and CRT implantation is safe and may be associated with improved survival, reduced need for continued hemodynamic support, reduced hospital readmission, and improvement in left ventricular ejection fraction.

Background: Symptomatic bradyarrhythmias necessitating permanent pacemaker implantation (PPI) predominantly affect elderly individuals with multiple cardiovascular risk factors. Coronary artery disease (CAD) is a known cause of conduction disturbances, and ischemia affecting the atrioventricular (AV) node or His bundle may present as bradyarrhythmias. However, CAD can be clinically silent, and traditional risk factors often correlate with the presence of coexistent CAD. The prevalence of CAD among pacemaker recipients has been shown to vary widely. Our study aims to assess the incidence of CAD in patients undergoing PPI for conduction abnormalities and identify clinical predictors of CAD in this population.Aim: This study aims to determine the coronary angiographic profile of patients undergoing permanent pacemaker insertion for conduction abnormalities to assess the incidence and characterization of CAD.Methods: We conducted a prospective, observational, single-center study at a tertiary care institute, enrolling adult patients with symptomatic bradyarrhythmias (high-grade AV block or sinus node dysfunction) undergoing PPI. We excluded patients with acute coronary syndrome and those with conditions that would preclude invasive procedures. Clinical and demographic data were collected, including a detailed history of coronary risk factors. All patients underwent coronary angiography prior to or during PPI to assess the presence and severity of CAD. CAD was classified as non-obstructive (plaque <50% stenosis) or obstructive (≥50% stenosis). Statistical analysis was performed using chi-square and Student’s t-test, with p<0.05 considered significant.Results: Among 50 patients (mean age 67 ± 12.5 years), 25 (50%) had normal coronary findings, while 25 (50%) had CAD. Of those with CAD, 11 (22%) had non-obstructive plaques, and 14 (28%) had obstructive CAD. The most common coronary artery involved was the left anterior descending (LAD) artery. Seven patients with obstructive CAD underwent percutaneous coronary intervention (PCI), and seven received optimal medical therapy. Risk factors such as diabetes mellitus (p=0.015) and hypertension (p=0.005) were significantly associated with the presence of obstructive CAD. Echocardiographic findings such as left ventricular ejection fraction (LVEF) and regional wall motion abnormalities (RWMA) were not reliable predictors of CAD presence.Conclusions: Our study demonstrates that CAD is common among patients undergoing PPI, with a significant proportion having obstructive CAD despite being asymptomatic. Diabetes and hypertension were identified as key risk factors for CAD in this population. The findings suggest that coronary angiography should be considered routinely in high-risk patients undergoing PPI, as it can identify silent CAD and guide therapeutic decisions, ultimately improving prognosis.

Rationale:Atrial fibrillation (AF) is characterized by rapid and disordered atrial electrical activity. Rhythm and rate control are the primary strategies applied in AF management. In clinical practice, the patient’s symptoms, comorbidities, drug tolerance, cardioversion effectiveness, and risk of disease must be comprehensively evaluated to reasonably recommend strategies for rhythm and rate control.Patient concerns:A 65-year-old Asian man experienced persistent AF complicated by malignant arrhythmia. He was poorly treated with medications, which led to heart failure and repeated wide QRS complex tachycardia episodes.Diagnoses:Based on the patient’s overall presentation and electrocardiographic monitoring findings, a diagnosis of persistent AF complicated with malignant arrhythmia and heart failure was made.Interventions:To restore sinus rhythm, improve myocardial synchronization, and prevent malignant arrhythmia induced by AF, a one-stop treatment strategy of AF catheter ablation combined with atrioventricular nodal ablation and left bundle optimized cardiac resynchronization therapy was adopted for the patient.Outcomes:At follow-up after 1 year, his N-terminal pro-brain natriuretic peptide level decreased, cardiac shadow reduced, and left ventricular ejection fraction increased. Atrial high-rate episodes were detected without the occurrence of any malignant arrhythmia. Since then, the patient has not developed cardiac insufficiency or syncope.Lessons:When drug therapy alone is not satisfactorily effective, AF catheter ablation can optimally maintain sinus rhythm. However, considering that sinus rhythm may be difficult to maintain and secondary malignant arrhythmia may be fatal, atrioventricular nodal ablation may be performed to eliminate the effects of AF and rapid ventricular rate, whereas physiological pacing, including left bundle optimized cardiac resynchronization therapy, can be performed to restore the sequence of optimal cardiac contractions. The one-stop comprehensive treatment strategy described herein would be a good option under certain conditions.