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The article discusses the case of a 39-year-old woman with a history of atrial septal defect and sick sinus syndrome, who received a dual-chamber pacemaker. Initially, the pacemaker functioned well with a ventricular pacing rate of 1.3%, but this increased to 7.4% within three months. The device's Managed Ventricular Pacing (MVP) mode, which prioritizes native AV conduction to minimize unnecessary ventricular pacing, was effective but revealed complications with junctional rhythms.

Chronic atrial and intestinal dysrhythmia (CAID) syndrome is a rare disorder affecting the heart and digestive systems. It results in bradycardia and arrhythmia due to sinoatrial node involvement. Concurrently, intestinal pseudo-obstruction arises from anomalies in the Cajal cells, recognized as the pacemakers of the intestine. Patients may experience dizziness, drowsiness, syncope, and palpitations attributed to the arrhythmia, while abdominal pain, distension, vomiting, and constipation can occur due to intestinal pseudoobstruction. This report discusses the treatment management for two patients diagnosed with CAID syndrome. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most common arrhythmia in cardiovascular disease, and it often coexists and interacts with sick sinus syndrome. In the past, pacemaker implantation combined with antiarrhythmic drugs was preferred for symptomatic atrial fibrillation with long interval treatment. However, in recent years, more and more studies have shown that compared with pacemaker implantation, radiofrequency ablation can reduce the hospitalization rate related to tachycardia, effectively control atrial fibrillation, and improve patient prognosis and hospitalization rate of heart failure. However, some patients present intrinsic sinus node dysfunction (SND), and SND may progress and worsen in some patients with atrial fibrillation. Therefore, the first-line treatment strategy for patients with atrial fibrillation with long interval remains controversial. This article reviews the selection of long-term intermittent treatment strategies for atrial fibrillation.

Abstract Objective By employing network pharmacology alongside molecular docking techniques, we can delve into the intricate workings of Yixin-Fumai granules (YXFMs) and their impact on sick sinus syndrome (SSS) within wrinkles mice. Specifically, we aim to understand how YXFMs enhance autophagy through the PI3K/AKT/FOXO path. Methods The active ingredients and medicinal uses of Ginseng, ligusticum wallichii, Ophiopogon, Schisandra, salvia, and astragalus were compiled using the BATMAN-TCM database. We also used Genecards, OMIM, and Disgenet files to identify the disease goals. A hierarchical diagram of “disease-drug-key targets” was generated using the Cytoscape programs. In addition, we established a target protein interaction (PPI) network using the STRING database. Then, the Cluster Profiler R package was used to conduct GO functional enrichment evaluation and KEGG pathway enrichment analyses of the targets. Based on the PPI system, we chose the top communicating targets and substances over molecular docking. In vivo studies were performed to validate these selections further. The mouse model was induced to study the damaged sinoatrial node (SAN) in mice with lower heart rates due to age-related changes. Electrocardiogram and Masson staining assessments were performed to obtain the results. The transmission electron microscope was used to assess the autophagy level of SAN cells. Western blot was employed to analyze the impact of YXFMs on protein expression in the PI3K/AKT/FOXO signaling process throughout SSS therapy in aging mice. Results One hundred forty-two active ingredients, 1858 targets, 1226 disease targets, and 266 intersection targets were obtained. The key targets of the PPI network encompassed TP53, AKT1, CTNNB1, INS, and TNF, among others. According to GO functional analysis, the mechanism underlying YXFMs in SSS treatment may primarily be associated with the control of ion transport across membranes, cardiac contraction, regulation of blood circulation, and other biological processes. Based on the results of KEGG pathway enrichment analysis, it was determined that they were mainly enriched in multiple pathways of signaling such as the PI3K-Akt signaling route, MAPK signaling process, AGE-RAGE signaling path, FOXO signaling path, HIF-1 signaling process, and several other paths. Molecular docking demonstrated that five compounds had excellent binding to the key candidate target proteins AKT1 and INS. Through the in vivo studies, we noticed notable effects when administering YXFMs. These effects included the suppression of aging-induced SSS, a decrease in the R-R interval, a rise in heart rate, a reduction in fibrosis, a boost in the autophagy process level, and a spike in the levels of expression of key protein molecules in the PI3K/AKT/FOXO signaling path. Conclusion This research has made preliminary predictions about the potential of YXFMs in treating SSS. It suggests that YXFMs may have the ability to target key proteins and critical paths associated with the condition. Further testing has been conducted to discover new findings and evidence of ideas for tackling SSS triggered by aging.

Remdesivir (RDV) is the first drug approved by the FDA for clinical treatment of hospitalized patients infected with COVID-19 because it has been shown to have good antiviral activity against a variety of viruses, including Arenaviridae and Coronaviridae viral families. However, it has been reported that its clinical treatment leads to the symptoms of sick sinus syndrome such as sinus bradycardia, conduction block, and sinus arrest, but the electrophysiological mechanism of its specific cardiac adverse events is still unclear. We report complementary, experimental, studies of its electrophysiological effects. In wireless cardiac telemetry experiments in vivo and electrocardiographic studies in ex vivo cardiac preparations, RDV significantly caused sinus bradycardia, sinus atrial block, and prolongation of the QT interval in guinea pigs. Dose-dependent effects of RDV on the electrical activities of sinoatrial node (SA node) preparations of guinea pigs were characterised by multielectrode, optical RH237 voltage mapping. These revealed reversibly reduced sinoatrial conduction time (SACT), increased AP durations (APDs), and decreased the pacemaking rate of the SA node. Patch-clamp experiments showed that RDV significantly inhibited the If current of HCN4 channels, resulting in a significant decrease in the spontaneous firing rate of SA node cells, which may underlie the development of sick sinus node syndrome. In addition, RDV significantly inhibits IKr currents in hERG channels, leading to prolongation of the QT interval and playing a role in bradycardia. Therefore, these findings provide insights into the understanding the bradycardia effect of RDV, which may be used as basic theoretical guidance for the intervention of its adverse events, and prompt safety investigations of RDV's cardiac safety in the future. [ABSTRACT FROM AUTHOR]

Background: There is limited research on the intra‐individual efficacy of ventricular pacing minimization algorithms developed by Biotronik—the Ventricular Pace Suppression algorithm (VpS) and the Intrinsic Rhythm Support plus algorithm (IRSplus) (BIOTRONIK SE & Co. KG, Berlin, Germany). We performed a randomized pilot trial that evaluated the efficacy of two algorithms in patients with symptomatic sinus node dysfunction (SND) who received a dual‐chamber pacemaker. Methods: The trial was conducted in 11 tertiary hospitals in South Korea. The patients were randomized to either the VpS or IRSplus algorithm group after a 3‐month period of fixed atrioventricular (AV) delay. The primary outcome was the ventricular pacing percentage (Vp%) at each follow‐up visit. The secondary outcomes were the occurrence of heart failure (HF) and atrial fibrillation (AF) during the study period. Results: Data from 131 patients were analyzed. Initially, their average Vp% over 3 months with a fixed AV interval was 14.1 ± 19.4%. Patients were randomly assigned to VpS and IRSplus groups, with 66 and 65 in each. Algorithms reduced average Vp% to 4.0 ± 11.3% at 9 months and 6.7 ± 14.9% at 15 months. These algorithms were more effective for patients with paced AV delay (PAVD) ≤300 ms compared to those with PAVD >300 ms. Both algorithms were equally effective in reducing Vp%. Clinical AF or HF hospitalization was not observed during the study period. Conclusion: The VpS and IRSplus algorithms are effective and safe in minimizing unnecessary ventricular pacing in patients with SND. [ABSTRACT FROM AUTHOR]

Objective: By employing network pharmacology alongside molecular docking techniques, we can delve into the intricate workings of Yixin-Fumai granules (YXFMs) and their impact on sick sinus syndrome (SSS) within wrinkles mice. Specifically, we aim to understand how YXFMs enhance autophagy through the PI3K/AKT/FOXO path. Methods: The active ingredients and medicinal uses of Ginseng, ligusticum wallichii, Ophiopogon, Schisandra, salvia, and astragalus were compiled using the BATMAN-TCM database. We also used Genecards, OMIM, and Disgenet files to identify the disease goals. A hierarchical diagram of "disease-drug-key targets" was generated using the Cytoscape programs. In addition, we established a target protein interaction (PPI) network using the STRING database. Then, the Cluster Profiler R package was used to conduct GO functional enrichment evaluation and KEGG pathway enrichment analyses of the targets. Based on the PPI system, we chose the top communicating targets and substances over molecular docking. In vivo studies were performed to validate these selections further. The mouse model was induced to study the damaged sinoatrial node (SAN) in mice with lower heart rates due to age-related changes. Electrocardiogram and Masson staining assessments were performed to obtain the results. The transmission electron microscope was used to assess the autophagy level of SAN cells. Western blot was employed to analyze the impact of YXFMs on protein expression in the PI3K/AKT/FOXO signaling process throughout SSS therapy in aging mice. Results: One hundred forty-two active ingredients, 1858 targets, 1226 disease targets, and 266 intersection targets were obtained. The key targets of the PPI network encompassed TP53, AKT1, CTNNB1, INS, and TNF, among others. According to GO functional analysis, the mechanism underlying YXFMs in SSS treatment may primarily be associated with the control of ion transport across membranes, cardiac contraction, regulation of blood circulation, and other biological processes. Based on the results of KEGG pathway enrichment analysis, it was determined that they were mainly enriched in multiple pathways of signaling such as the PI3K-Akt signaling route, MAPK signaling process, AGE-RAGE signaling path, FOXO signaling path, HIF-1 signaling process, and several other paths. Molecular docking demonstrated that five compounds had excellent binding to the key candidate target proteins AKT1 and INS. Through the in vivo studies, we noticed notable effects when administering YXFMs. These effects included the suppression of aging-induced SSS, a decrease in the R-R interval, a rise in heart rate, a reduction in fibrosis, a boost in the autophagy process level, and a spike in the levels of expression of key protein molecules in the PI3K/AKT/FOXO signaling path. Conclusion: This research has made preliminary predictions about the potential of YXFMs in treating SSS. It suggests that YXFMs may have the ability to target key proteins and critical paths associated with the condition. Further testing has been conducted to discover new findings and evidence of ideas for tackling SSS triggered by aging. [ABSTRACT FROM AUTHOR]

The research utilized network pharmacology to explore how Yixin Fumai granules mitigate sinoatrial node fibrosis caused by D-galactose in older mice by altering inflammatory reactions. Effective ingredients and targets of Yixin Fumai granules (including ginsenoside, ophiopogonin, schisandrin, astragaloside, danshensu, and ligustilide) were screened from traditional Chinese medicine systems pharmacology and BATMANtraditional Chinese medicine databases. Targeted diseases were pinpointed using GeneCards, Online Mendelian Inheritance in Man, and Disgenet databases. By employing Cytoscape 3.7.2 software, a network targeting drug-effective ingredients-targets was created, accompanied by a protein-protein interaction network formed via the Search Tool for the Retrieval of Interacting Genes databases. To forecast the fundamental processes, analyses of Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway enrichment were conducted utilizing the R language. The expression levels of the Nucleotide oligomerization domain-like receptor protein 3, caspase-1, gasdermin D, interleukin-1 beta, and interleukin-18 genes were assessed through reverse transcription polymerase chain reaction. A total of 127 components were identified, with major components including quercetin, beta-sitosterol, kaempferol, naringenin, ginsenoside Rb1, and beta-eudesmol. There were 129 therapeutic targets identified, including key targets such as tumor necrosis factor, protein kinase B serine/threonine kinase 1, interleukin-6, tumor protein P53, interleukin-1 beta, and vascular endothelial growth factor A. The experimental findings revealed that the Yixin Fumai granules group mice, in contrast to the model group, showed enhanced mental health, a standard diet, notably better coat color, and zero fatalities. The echocardiographic results showed a rise in ejection fraction and fractional shortening, a faster heart rate, a reduction in left ventricular internal diameter end systole and left ventricular internal diameter end diastole, and an increase in left ventricular posterior wall end systole and left ventricular posterior wall end diastole in the Yixin Fumai granules group relative to the model group. This study preliminarily elucidated the active ingredients, targets, and pathways through which Yixin Fumai granules treat sick sinus syndrome using network pharmacology and further validated its mechanism through experimental verification. These findings provide new evidence and research directions for treating sick sinus syndrome induced by aging. [ABSTRACT FROM AUTHOR]

Introduction: Implantable permanent pacemaker function is supported by their energy sources for a mean period of 8.8–12.4 years. We previously published this case of a patient with a normally functioning VVI pacemaker, 31 years after implantation. Methods and Results: In this report, we state that the device is still functioning normally 40 years after implantation. The most recent device interrogation revealed pacing threshold of 0.9 V/0.5 ms. Holter monitoring for 24 hours recorded a total of 98.707 beats with 97.78% paced beats, without any indication of pacemaker malfunction and with stable heart rate at 70–71 bpm. Conclusion: Most patients with implantable devices have the appropriate follow‐up and settings of low energy consumption. Manufacturing companies should focus on prolonging device longevity, to produce future devices with higher energy capacity. [ABSTRACT FROM AUTHOR]

The Annual Report on Cardiovascular Health and Diseases in China (2022) intricate landscape of cardiovascular health in China. In connection with the previous section, this seventh section of the report offers a comprehensive analysis of disorders of heart rhythm in China. In 2021, China has achieved significant development and gratifying results in many aspects of the field of arrhythmia. Left bundle branch pacing (LBBP), as an emerging pacing technique originating from China, has received widespread attention. New research results have emerged on its indications, surgical procedures, clinical evaluation, and comparison with other pacing techniques. Its feasibility, effectiveness, and safety have been basically verified, but its long-term prognosis still needs further confirmation from larger samples and longer follow-up time research results. Leadless pacemakers have begun to be used in a wider range of clinical applications, and related large sample cohort studies have been reported. In addition, there are also noteworthy new achievements in the fields of pacemaker remote programming, anticoagulation and radiofrequency catheter ablation (RFCA) therapy for atrial fibrillation, and implantable cardioverter defibrillator prevention of sudden cardiac death. In terms of clinical practice, due to COVID-19 pandemic, the number of RFCA procedures and other device implantations in China has fluctuated, but it has gradually recovered since 2020. [ABSTRACT FROM AUTHOR]

Although ventricular capture during the atrial threshold test is possible, there are rare reports on the insulation defect and inactive leads thereof. In this case, we present a pacemaker‐dependent patient with a history of pacemaker generator replacements. The patient experienced ventricular capture induced by atrial pacing due to adhesion of the atrial and ventricular leads with an insulation defect. The atrial lead was abandoned and a new lead was implanted. However, there was a significant decrease in ventricular impedance detected shortly after the new lead was implanted. When observing the phenomenon of atrial pacing‐induced ventricular depolarization, one uncommon reason to consider is lead adhesive wear. It is important to pay attention to the contact and bending sites of the leads. [ABSTRACT FROM AUTHOR]

Abstract Background Clinical outcomes after catheter ablation (CA) or pacemaker (PM) implantation for the tachycardia–bradycardia syndrome (TBS) has not been evaluated adequately. We tried to compare the efficacy and safety outcomes of CA and PM implantation as an initial treatment option for TBS in paroxysmal atrial fibrillation (AF) patients. Methods Sixty-eight patients with paroxysmal AF and TBS (mean 63.7 years, 63.2% male) were randomized, and received CA (n = 35) or PM (n = 33) as initial treatments. The primary outcomes were unexpected emergency room visits or hospitalizations attributed to cardiovascular causes. Results In the intention-to-treatment analysis, the rates of primary outcomes were not significantly different between the two groups at the 2-year follow-up (19.8% vs. 25.9%; hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.25–2.20, P = 0.584), irrespective of whether the results were adjusted for age (HR 1.12, 95% CI 0.34–3.64, P = 0.852). The 2-year rate of recurrent AF was significantly lower in the CA group compared to the PM group (33.9% vs. 56.8%, P = 0.038). Four patients (11.4%) in the CA group finally received PMs after CA owing to recurrent syncope episodes. The rate of major or minor procedure related complications was not significantly different between the two groups. Conclusion CA had a similar efficacy and safety profile with that of PM and a higher sinus rhythm maintenance rate. CA could be considered as a preferable initial treatment option over PM implantation in patients with paroxysmal AF and TBS. Trial registration KCT0000155.

Background: Clinical outcomes after catheter ablation (CA) or pacemaker (PM) implantation for the tachycardia–bradycardia syndrome (TBS) has not been evaluated adequately. We tried to compare the efficacy and safety outcomes of CA and PM implantation as an initial treatment option for TBS in paroxysmal atrial fibrillation (AF) patients. Methods: Sixty-eight patients with paroxysmal AF and TBS (mean 63.7 years, 63.2% male) were randomized, and received CA (n = 35) or PM (n = 33) as initial treatments. The primary outcomes were unexpected emergency room visits or hospitalizations attributed to cardiovascular causes. Results: In the intention-to-treatment analysis, the rates of primary outcomes were not significantly different between the two groups at the 2-year follow-up (19.8% vs. 25.9%; hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.25–2.20, P = 0.584), irrespective of whether the results were adjusted for age (HR 1.12, 95% CI 0.34–3.64, P = 0.852). The 2-year rate of recurrent AF was significantly lower in the CA group compared to the PM group (33.9% vs. 56.8%, P = 0.038). Four patients (11.4%) in the CA group finally received PMs after CA owing to recurrent syncope episodes. The rate of major or minor procedure related complications was not significantly different between the two groups. Conclusion: CA had a similar efficacy and safety profile with that of PM and a higher sinus rhythm maintenance rate. CA could be considered as a preferable initial treatment option over PM implantation in patients with paroxysmal AF and TBS. Trial registration: KCT0000155. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is currently defined as symptomatic by asking patients if they are aware of when they are in AF and if they feel better in sinus rhythm. However, this approach of defining AF as symptomatic and asymptomatic fails to adequately consider the adverse effects of AF in patients who are unaware of their rhythm including progression from paroxysmal to persistent AF, and the development of dementia, stroke, sinus node dysfunction, valvular regurgitation, ventricular dysfunction, and heart failure. Labeling these patients as asymptomatic falsely suggests that their AF requires less intense therapy and puts into question the notion of truly asymptomatic AF. Because focusing on patient awareness ignores other important consequences of AF, clinical endpoints that are independent of symptoms are being developed. The concept of AF burden has more recently been used as a clinical endpoint in clinical trials as a more clinically relevant endpoint compared to AF‐related symptoms or time to first recurrence, but its correlation with symptoms and other clinical outcomes remains unclear. This review will explore the impact of AF on apparently asymptomatic patients, the use of AF burden as an endpoint for AF management, and potential refinements to the AF burden metric. The review is based on a presentation by the senior author during the 2023 16th annual European Cardiac Arrhythmia Society (ECAS) congress in Paris, France. [ABSTRACT FROM AUTHOR]

IntroductionLithium is a well-known agent to cause systemic toxicity with its narrow therapeutic window. Toxic cardiac effects are known but seldomly reported and can manifest as sinus node dysfunction (SND) ranging from delayed conduction to sinus arrest with the potential to induce asystole. Theophylline a positive chronotropic agent has been previously used for correction of sinus node dysfunction but never been utilized for the correction of lithium-induced SND. We report the first successful use of Theophylline for rate/rhythm correction of SND in a patient presenting with acute lithium toxicity along with a review summarizing the clinical features of all published literature regarding lithium-induced SND.MethodsCase report and systematic review of the literature are presented. Three independent scientific databases were queried for reports of lithium-induced SND. A clinical compendium was then generated detailing associated clinical data and descriptive statistics were performed.Results1,117 reports were initially retrieved with full-text review yielding a cohort of 49 unique, independent studies. (61.4%) of patients presented with a supratherapeutic lithium level, 12 (21.1%) were normotherapeutic, and 11 (19.3%) were subtherapeutic. EKG findings varied but most commonly described sinus node dysfunction with a variable degree of sinoatrial block with sinus bradycardia (54.39%) and sinus arrest (29.82%) predominating. Twelve patients (21.1%) required inotrope or vasopressor support. 10 (17.5%) of patient required temporary pacing while 7 (12.3%) required permanent pacemaker implantation. In the majority of cases no significant permanent sequelae were reported as 50 (87.7%) patients recovered, 2 (3.5%) patients had persistent sinus node dysfunction, and 2 (3.5%) patients expired as a result of acute lithium toxicity.Discussion & conclusionIn this review we report the most up-to-date and comprehensive clinical compendium of lithium-associated sinus node dysfunction along with describing a novel treatment methodology to rapidly correct lithium-induced cardiac toxicity in a patient with long-standing bipolar disorder on chronic lithium treatment. We have reviewed the available literature and provide a comprehensive summary detailing symptomatology of presentation, treatments utilized, electrocardiographic findings and patient prognoses. We have concluded that under the presumptive conditions that transient sinus node dysfunction will resolve with elimination of toxic concentrations of lithium, temporary chronotropic support provided by theophylline administration would be preferable to more invasive measures such as hemodialysis, temporary pacing, or implantation of a permanent pacemaker.

The sinoatrial node (SAN), the leading pacemaker region, generates electrical impulses that propagate throughout the heart. SAN dysfunction with bradyarrhythmia is well documented in heart failure (HF). However, the underlying mechanisms are not completely understood. Mitochondria are critical to cellular processes that determine the life or death of the cell. The release of Ca2+ from the ryanodine receptors 2 (RyR2) on the sarcoplasmic reticulum (SR) at mitochondria-SR microdomains serves as the critical communication to match energy production to meet metabolic demands. Therefore, we tested the hypothesis that alterations in the mitochondria-SR connectomics contribute to SAN dysfunction in HF. We took advantage of a mouse model of chronic pressure overload-induced HF by transverse aortic constriction (TAC) and a SAN-specific CRISPR-Cas9-mediated knockdown of mitofusin-2 (Mfn2), the mitochondria-SR tethering GTPase protein. TAC mice exhibited impaired cardiac function with HF, cardiac fibrosis, and profound SAN dysfunction. Ultrastructural imaging using electron microscope (EM) tomography revealed abnormal mitochondrial structure with increased mitochondria-SR distance. The expression of Mfn2 was significantly down-regulated and showed reduced colocalization with RyR2 in HF SAN cells. Indeed, SAN-specific Mfn2 knockdown led to alterations in the mitochondria-SR microdomains and SAN dysfunction. Finally, disruptions in the mitochondria-SR microdomains resulted in abnormal mitochondrial Ca2+ handling, alterations in localized protein kinase A (PKA) activity, and impaired mitochondrial function in HF SAN cells. The current study provides insights into the role of mitochondria-SR microdomains in SAN automaticity and possible therapeutic targets for SAN dysfunction in HF patients.

Introduction: Pacemaker implantation can be challenging in patients with congenital heart disease. Methods and Results: In a patient with Ebstein disease and symptomatic sinus node dysfunction, despite multiple attempts, the Micra® pacemaker could not be implanted in the severely dilated right ventricle. In that context, and after iodine injection to confirm the appropriate location, the Micra® pacemaker was successfully implanted in the right appendage at the first attempt. Conclusion: Despite the recent development of dedicated dual‐chamber leadless pacemaker, to the best of our knowledge, this case is the first off‐label Micra® implantation in a right appendage. [ABSTRACT FROM AUTHOR]

Introduction: Severe transitory episodes of bradycardia with subsequent syncope in children are common, and generally portend a benign prognosis. Rarely, patients may experience prolonged asystolic episodes secondary to significant sinus pauses (SP) or paroxysmal atrioventricular block (AVB). Cardioneuroablation (CNA) is a catheter‐based intervention, used to identify and ablate the epicardial ganglionated plexi (GP), which results in disruption of the vagal‐mediated parasympathetic input to the sinus and atrioventricular node. Objective: Describe the methodology and role of CNA for treatment of pediatric patients with functional AVB or SP. Methods: This is a single‐center, case series study. Patients with SP or AVB, 21 years of age or younger, who underwent CNA between 2015 and 2021 were included. CNA was performed via anatomically guided and high‐frequency stimulation methods. Results: Six patients were included. The median age was 18.9 years (range 12.3–20.9 years), 33% female. Two patients had prolonged SP, two had paroxysmal AVB, and two had both SP and AVB. Four patients had prior syncope. The median longest pause was 8.9 s (range 3.9–16.8) with 11 total documented pauses (range 2–231) during the 6 months pre‐CNA. Post‐CNA, the median longest pause was 1.3 s (range 0.8–2.2) with one documented SP after termination of atrial tachycardia at the 3‐month follow‐up. At 6 months, the median longest pause was 1.1 s (0.8–1.3) with 0 documented pauses. No patients had syncope post‐CNA. Conclusion: CNA may be an effective alternative to pacemaker implantation in pediatric patients with syncope or significant symptoms secondary to functional SP or AVB. [ABSTRACT FROM AUTHOR]

A seven-year-old female neutered Parson Russel terrier was referred for syncopal episodes. An electrocardiogram revealed paroxysmal atrial flutter followed by periods of sinus arrest, suggesting sick sinus syndrome. Echocardiography showed severe biventricular wall thickening (hypertrophic cardiomyopathy (HCM) phenotype) with no signs of fixed or dynamic left ventricular outflow tract obstruction. Blood pressure, abdominal ultrasound, serum total thyroxin and thyroid-stimulating hormone, and insulin-like growth factor-1 were all within normal limits. Cardiac troponin I was elevated (1.7 ng/mL, ref<0.07). Serological tests for common infectious diseases were negative. A 24-h Holter confirmed that the syncopal episodes were associated with asystolic pauses (sinus arrest after runs of atrial flutter) ranging between 8.5 and 9.6 s. Right ventricular endomyocardial biopsies (EMB) were performed at the time of pacemaker implantation to assess for storage or infiltrative diseases that mimic HCM in people. Histological analysis of the EMB revealed plurifocal inflammatory infiltrates with macrophages and lymphocytes (CD3+ > 7/mm2) associated with myocyte necrosis, but no evidence of myocyte vacuolisation or infiltrative myocardial disorders. These findings were compatible with myocardial ischaemic injury or acute lymphocytic myocarditis. Molecular analysis of canine cardiotropic viruses were negative. The dog developed refractory congestive heart failure and was euthanised 16 months later. Cardiac post-mortem examination revealed cardiomyocyte hypertrophy and disarray with diffuse interstitial and patchy replacement fibrosis, and small vessel disease, confirming HCM. We described a systemic diagnostic approach to an HCM phenotype in a dog, where a diagnosis of HCM was reached by excluding HCM phenocopies. [ABSTRACT FROM AUTHOR]

Transcatheter closure of superior vena cava (SVC) form of sinus venosus defects (SVDs) using covered stents is emerging as an alternative to surgery in the current decade. A covered stent placed in the cavoatrial junction creates a roof for the right upper pulmonary vein (RUPV) that stops the left-to-right shunt and redirects the vein to the left atrium. While surgical literature has clearly documented the incidence of stenosis of SVC and RUPV, sinus nodal dysfunction, and persistent residual shunts following surgical correction, it is imperative to have similar data after this new transcatheter intervention on the incidence of complications and follow-up outcomes. Since patients with pretricuspid shunts are often clinically asymptomatic, correction is primarily performed to prevent a persistent right heart volume overload and allow remodeling of the heart chambers. Any residual left-to-right shunt after a correction will result in persistent right heart dilatation. Residual flows can result from various mechanisms, including lack of apposition of the covered stent to the free edge of the SVD, fabric breach, and persistent anomalous drainage of additional right-sided pulmonary veins that drain very high in the SVC or can be due to a coexistent defect in the oval fossa. This review analyzes the different mechanisms, explains the transesophageal and angiographic images for each one, and offers solutions tailored for various reasons. Different mechanisms warrant different treatment principles. A solution for residual shunt from one mechanism may not be appropriate for residual flow through another mechanism. A thorough understanding would aid the operator in effective interventions for these SVDs. [ABSTRACT FROM AUTHOR]

Objectives: To determine the frequency of AF in patients after implantation of permanent pacemaker. Methodology: This longitudinal observational study was conducted in the department of cardiology Hayatabad Medical Complex from 1st September 2018 to 31st August 2019 through a descriptive cross sectional study design, total of 58 patients were included in this study. Results: Total of 58 patients were included in the study. Sample size calculated by WHO sample size calculator using 95%confidence interval and 5% error. 29 (50%) patients had no comorbidity, 5 (8.5%) patients were Diabetic, 17 (29.3%) patients were hypertensive, 7 (12.1%) patients were having CAD. 15 (25.9%) Patients had normal Echo Report with ejection fraction >55%, 34 (58.6%) Patients had Preserved LV Function, 9 (15.5%) Patients were recorded with impaired LV Function. 32 (55.2%) had VVIR Device implanted whereas in 26 (44.8%) patients DDDR Device was implanted. 58 (100%) patients had Sinus Rhythm during implantation. At one month follow up, 56 (96.6%) had Sinus Rhythm, 2 (3.4%) patients had Atrial Fibrillation. At one year, 50 (85.2%) patients had sinus Rhythm and 8 (13.8%) patients had AF. 13 (22.4%) patients had developed Heart Failure. Conclusions: Our study showed AF burden initially decreased significantly but over long-term AF significantly increased progressively. [ABSTRACT FROM AUTHOR]

Background: The temporary pacing lead routinely is placed into right ventricular (RV), which pose a risk of dislocation and cardiac perforation. Objective: We aim to evaluate the effectiveness and safety of temporary transvenous cardiac pacing (TTCP) leads placement into the coronary sinus vein (CSV) in patients with sick sinus syndrome (SSS). Methods: We investigated patients with SSS who underwent TTCP lead placement into the CSV under the guidance of X‐ray between January 2013 and May 2023. Patients were randomly divided into two groups: RV group (n = 33) and CSV group (n = 22). The ordinary passive bipolar electrodes were applied in both groups. In RV groups, electrodes were placed into RV. In CSV group, electrodes were placed into CSV. We evaluated the operation duration, fluoroscopic exposure, first‐attempt success rate of leads placement, pacing threshold, success rate of leads placement, rate of leads displacement, and complications. Results: Compared with that in RV group, the procedure time, fluoroscopic exposure was significantly prolonged, while the first‐attempt success rate of lead placement was obviously increased in CSV group (both p <.05). Compared with that in RV group, the rate of leads displacement is lower in CSV group (both p <.05). There were three patients occurred cardiac perforation in RV group, but no cardiac perforation was reported in CSV group (p >.05). Conclusion: TTCP leads placement into the CSV is an effective and safe strategy in patients with SSS. It indicates a high rate of pacing effectiveness with low device replacement and complication rates. [ABSTRACT FROM AUTHOR]

Background. Pacemakers are used to treat syncope in patients with bradyarrhythmia; however, the risk of recurrent syncope has only been investigated in few and smaller studies. Objective. The aim of this study was to investigate the risk of recurrent syncope after pacemaker implantation in patients with bradyarrhythmia and prior syncope. Methods. This retrospective, population-based cohort study included patients with a prior syncope and implantation of a pacemaker using data from the Danish nationwide registers from 1996 to 2017. Cumulative incidence and cox regression was used to estimate the 5-year incidence and the risk of recurrent syncope, respectively. Results. In total, 11,126 patients (median age: 78 years, interquartile range: 69-85, 56% male) were included and the 5-year cumulative incidence of recurrent syncope was 19.6% (95% confidence interval (CI): 18.8-20.3%). Sinus node dysfunction (hazard ratio [HR]: 1.29, 95%CI: 1.17-1.42) and unspecified type of bradyarrhythmia (HR: 1.32, 95%CI: 1.15-1.52) were associated with an increased risk of syncope compared to advanced atrioventricular (AV) block. Male sex (HR: 1.22, 95%CI: 1.22-1.34), cerebrovascular disease (HR: 1.17, 95%CI: 1.05-1.30), and prior number of syncopes were significantly associated with a higher HR of recurrent syncope. Conclusion. Almost one-in-five patients with bradyarrhythmia and prior syncope who had a pacemaker implanted had a recurrent syncope within five years. A higher risk of syncope was observed among patients with sinus node dysfunction and unspecified type of bradyarrhythmia compared to AV block. Male sex, cerebrovascular disease, and prior number of syncopes were associated risk factors of recurrent syncope. [ABSTRACT FROM AUTHOR]

Background: Permanent pacemaker (PPM) implantation is a well‐established treatment for symptomatic sinus node dysfunction (SND). The optimal timing of this intervention is unclear, with atrioventricular blocks often prioritized in resource stressed waiting lists due to mortality concerns. Methods: Mortality data was compared between patients receiving elective outpatient (OP) PPM implantation, and those presenting to hospital for urgent inpatient (IP) management for symptomatic SND. Survival analysis was conducted using Kaplan‐Meier plots and compared using the log‐rank test. Univariable and multivariable Cox regression, as well as propensity score matching analyses were performed to assess the prognostic effect on 30‐day and 1‐year all‐cause mortality of inpatient implant. Results: Of the 1269 patients identified with isolated SND, 740 (58%) had PPMs implanted on an OP and 529 (42%) on an IP basis. Mortality was significantly worse in patients where management was driven by hospital admission on an urgent basis (Log‐Rank χ2 = 21.6, p < 0.001) and remained an independent predictor of 1‐year all‐cause mortality (HR 3.40, 95% CI 1.97–5.86, p < 0.001) on multivariable analysis. Conclusions: SND is predominantly a disease associated with ageing and comorbid populations, where avoidance of deconditioning, hospitalization acquired infections, and polypharmacy is advantageous. Admission avoidance is therefore the preferable strategy. [ABSTRACT FROM AUTHOR]

Left bundle branch pacing (LBBP) has been subject to increasing interest over the last few years due to its capacity for physiological conduction and its advantages compared to His bundle pacing. His bundle pacing has certain limitations, such as a small pacing area for the His bundle, a high threshold that leads to battery depletion, a low R-wave amplitude that may result in atrial or His oversensing, and ventricular signal undersensing. In this case series, four patients (two female and two male) aged 62.2 ± 8.4 years old with symptomatic sick sinus disease and no scar tissue in the interventricular septum underwent LBBP. All LBBPs were done with standard LBBP using a lumenless SelectSecure 3830 lead (Medtronic®, Minneapolis, USA) with a fixed helix. The lead parameters showed a good R-wave amplitudes (13 ± 7.4 mV) and a low threshold (0.77 ± 0.17 V @ 0.4 ms). All patients were discharged on the next day. During follow-up period of 13.3 ± 12.9 months, all patients were well and no complications were noted. In conclusion, LBBP may be as an alternative of novel conduction pacing techniques and can be done relatively easy and safe, even with limited experience center.

Abstract Background Intraoperative sinus arrest is rarely seen during zygomatic fracture treatment. The patient was diagnosed with sick sinus syndrome based on repeated postoperative sinus arrest, which could have resulted in death if diagnosed late, making this case very significant to report. Case presentation Sick sinus syndrome is an arrhythmia associated with reduced automaticity of the sinoatrial node or impaired sinoatrial node conduction. We report the case of a 67-year-old man diagnosed with the syndrome after a sinus arrest that occurred during a zygomatic fracture treatment. The patient had cheek pain and mouth opening disorder, dizziness after fainting and sustaining a facial injury. Preoperative examination determined that the syncope was due to drug-induced arrhythmia, and surgery was authorized after drug withdrawal. During the operation, sinus arrest was observed due to trigeminal vagal reflex, and heart rate was restarted by stopping the operation and chest compressions. After the surgery, the patient showed symptoms of dizziness and palpitations, and sinus arrest following atrial fibrillation and supraventricular tachycardia, which was diagnosed as sick sinus syndrome, and a pacemaker was implanted. Currently, 8 years have passed since the surgery, and there are no symptoms of mouth opening disorder, dizziness, or palpitations. Conclusions In the case of maxillofacial injuries due to syncope, cardiogenic syncope is a possibility, and repeated syncope is a risk for death due to delayed diagnosis. There are no reports of maxillofacial trauma leading to a diagnosis of sick sinus syndrome. The purpose of this case report is to disseminate the importance of diagnosing the cause of syncope as well as injury treatment.

Previously we showed the generation of a protein trap library made with the gene-break transposon (GBT) in zebrafish (Danio rerio) that could be used to facilitate novel functional genome annotation towards understanding molecular underpinnings of human diseases (Ichino et al, 2020). Here, we report a significant application of this library for discovering essential genes for heart rhythm disorders such as sick sinus syndrome (SSS). SSS is a group of heart rhythm disorders caused by malfunction of the sinus node, the heart's primary pacemaker. Partially owing to its aging-associated phenotypic manifestation and low expressivity, molecular mechanisms of SSS remain difficult to decipher. From 609 GBT lines screened, we generated a collection of 35 zebrafish insertional cardiac (ZIC) mutants in which each mutant traps a gene with cardiac expression. We further employed electrocardiographic measurements to screen these 35 ZIC lines and identified three GBT mutants with SSS-like phenotypes. More detailed functional studies on one of the arrhythmogenic mutants, GBT411, in both zebrafish and mouse models unveiled Dnajb6 as a novel SSS causative gene with a unique expression pattern within the subpopulation of sinus node pacemaker cells that partially overlaps with the expression of hyperpolarization activated cyclic nucleotide gated channel 4 (HCN4), supporting heterogeneity of the cardiac pacemaker cells.

BackgroundCOVID-19 and Fontan physiology have each been associated with an elevated risk of venous thromboembolism (VTE), however little is known about the risks and potential consequences of having both.Case presentationA 51 year old male with tricuspid atresia status post Fontan and extracardiac Glenn shunt, atrial flutter, and sinus sick syndrome presented with phlegmasia cerulea dolens (PCD) of the left lower extremity in spite of supratherapeutic INR in the context of symptomatic COVID-10 pneumonia. He was treated with single session, catheter directed mechanical thrombectomy that was well-tolerated.ConclusionsThis report of acute PCD despite therapeutic anticoagulation with a Vitamin K antagonist, managed with emergent mechanical thrombectomy, calls to attention the importance of altered flow dynamics in COVID positive patients with Fontan circulation that may compound these independent risk factors for developing deep venous thrombosis with the potential for even higher morbidity.

The article describes a pacemaker-induced R-on-T phenomenon in a septuagenarian with situs inversus and dextrocardia, resulting from a dual-chamber pacemaker insertion for sick sinus syndrome. Topics include pacemaker settings and intervals, the mechanism behind the R-on-T phenomenon due to post-atrial ventricular blanking periods, and the clinical implications of these findings in pacemaker-induced arrhythmias.