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Atrial standstill is a rare arrhythmogenic condition characterized by the absence of electrical and mechanical activity in the atria. The therapeutic options for these patients described in the current literature, in which no reversible cause is detected, are permanent cardiac pacing, anticoagulant, and heart failure treatment when the latter exists. We present a case of a young male with no personal or family history of cardiovascular disease, diagnosed with atrial standstill after multiple syncopal episodes, in whom, because of the high expected ventricular pacing percentage, we opted for conduction system pacing with left bundle branch area pacing.

The following case series presents three different pediatric patients with SCN5A- related disease. In addition, family members are presented to demonstrate the variable penetrance that is commonly seen. Identifying features of this disease is important, because even in the very young, SCN5A disorders can cause lethal arrhythmias and sudden death. [ABSTRACT FROM AUTHOR]

Background Juvenile onset of extensive atrial electromechanical failure, including atrial standstill, is a rare disease entity that may precede ventricular cardiomyopathy. Genetic variants associated with early-onset atrioventricular (AV) cardiomyopathy are increasingly recognized. Case summary A 16-year-old patient presented with atrial brady- and tachyarrhythmias and concomitant impaired atrial electromechanical function (atrial standstill). The atrial phenotype preceded the development of a predominantly right-sided AV dilated cardiomyopathy with pronounced myocardial fibrosis. A His-bundle pacemaker was installed for high-degree AV conduction block and sinus arrest. Using familial-based whole-exome sequencing, a missense mutation and a copy number variant deletion (compound heterozygosity) of the TAF1A gene (involved in ribosomal RNA synthesis) were identified. Discussion Juvenile onset of severe atrial electromechanical failure with atrial arrhythmias should prompt deep pheno- and genotyping and calls for vigilance for downstream cardiomyopathic deterioration. [ABSTRACT FROM AUTHOR]

ObjectiveTo characterize the cardiac phenotype associated with the novel pathogenic variant (c.1526del) of LMNA gene, which we identified in a large, six-generation family.Methods and ResultsA family tree was constructed. The clinical data of living and deceased family members were collected. DNA samples from 7 family members were analyzed for LMNA mutations using whole-exome high-throughput sequencing technology. The clinical presentation of pathogenic variant carriers was evaluated. In this six-generation family (n = 67), one member experienced sudden death at the age of 40-years-old. Three pathogenic variant carriers were identified to possess a novel heterozygous deletion mutation in LMNA gene (HGVS: NM_170707.4, c.1526del) located at exon 9 of LMNA chr1:156137145, which creates a premature translational stop signal (p.Pro509Leufs*39) in the LMNA gene and results in an mutant lamin A protein product. The main symptoms of the pathogenic variant carriers were palpitation, fatigue, and syncope, which typically occurred around 20-years-old. AV-conduction block and non-sustained ventricular tachycardia were the first signs of disease and would rapidly progress to atrial standstill around 30-years-old. Significant right atrial enlargement and bicuspid aortic valve malformation was also commonly seen in patients who carried this pathogenic variant.ConclusionThe pathogenic variant of c.1526del p.P509Lfs*39 was a frameshift deletion located at exon 9 of LMNA chr1:156137145 and causes severe right atrial enlargement, sick sinus syndrome, atrial standstill, ventricular tachycardia, and bicuspid aortic valve malformation. Our findings expand the phenotypic spectrum of novel LMNA gene mutations.

We report a case of atrial functional tricuspid regurgitation with an atrial standstill in a 71-year-old woman with a history of chronic atrial fibrillation (AF). The ECG showed a flat baseline with no AF waves and regular, narrow QRS complexes, whereas the previous ECG demonstrated AF. Echocardiography revealed dilation of the right atrium and the tricuspid annulus with severe regurgitation, but mitral regurgitation was mild. No atrial contraction was detected. Bilateral ventricular function was preserved. Cardiac catheterization showed no pulmonary hypertension and an a-wave in atrial pressure tracings. During surgery, epicardial pacing was unable to capture both atria. The tricuspid valve was replaced and a pacemaker was implanted., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Hori et al.)

Abstract Giant cell myocarditis (GCM) is a rare condition. Its association with SARS‐CoV‐2 has not been described before. The 46‐year‐old female patient was admitted to the clinic on September 2020. She had 7 year adrenal insufficiency history and infarct‐like debut of myocardial disease in November 2019. After COVID‐19 in April 2020, cardiac disease progressed. The examination showed low QRS voltage, QS complexes in V1–V5 leads, atrial standstill, left ventricular systolic and restrictive dysfunction, elevated anti‐heart antibodies, and subepicardial late gadolinium enhancement by magnetic resonance imaging. Endomyocardial biopsy and pacemaker implantation were performed, but the patient died suddenly due to ventricular tachycardia or ventricular fibrillation (the resuscitation was ineffective). The autopsy revealed GCM, SARS‐CoV‐2, and Parvovirus B19 were detected in the myocardium. The role of SARS‐CoV‐2 in the pathogenesis of autoimmune myocarditis is discussed.

Atrial standstill (AS) is a rare condition defined by the lack of atrial electrical and mechanical activities. It is usually clinically manifested as symptomatic bradycardia, which requires permanent pacemaker (PPM) implantation. Traditional right ventricular apical pacing causes electrical and mechanical dyssynchrony resulting in left ventricular dysfunction, heart failure, and arrhythmias. As a novel physiological pacing strategy, left bundle branch area pacing (LBBaP) has demonstrated effectiveness and safety in recent years, but its application in exceptional conditions is rarely reported. We report the case of a 47-year-old female, who was diagnosed with AS complicated with a giant atrium, and successfully received a single-chamber PPM with LBBaP.

Giant cell myocarditis (GCM) is a rare condition. Its association with SARS-CoV-2 has not been described before. The 46-year-old female patient was admitted to the clinic on September 2020. She had 7 year adrenal insufficiency history and infarct-like debut of myocardial disease in November 2019. After COVID-19 in April 2020, cardiac disease progressed. The examination showed low QRS voltage, QS complexes in V1–V5 leads, atrial standstill, left ventricular systolic and restrictive dysfunction, elevated anti-heart antibodies, and subepicardial late gadolinium enhancement by magnetic resonance imaging. Endomyocardial biopsy and pacemaker implantation were performed, but the patient died suddenly due to ventricular tachycardia or ventricular fibrillation (the resuscitation was ineffective). The autopsy revealed GCM, SARS-CoV-2, and Parvovirus B19 were detected in the myocardium. The role of SARS-CoV-2 in the pathogenesis of autoimmune myocarditis is discussed. [ABSTRACT FROM AUTHOR]

Introduction. Persistent atrial standstill is a rare syndrome characterized by absence of mechanical and electrical atrial activity. The article presents a unique case of atrial standstill in the newborn patient with tachyarrhythmia.Brief description. The first manifestation of atrial standstill in the patient was heart failure (HF) manifestations and wide-complex tachycardia according to electrocardiography, which was identified as ventricular tachycardia. At the local outpatient clinic, the child was prescribed with antiarrhythmic therapy (AAT), which decreased heart rate. Three months later, a transesophageal electrophysiological study was carried out in our center in order to determine the arrhythmia origin. A multiform idioventricular rhythm with a heart rate of 46-119 beats per min was diagnosed, atrial pacing spike (A waves) was not recorded. Given bradyarrhythmia, hemodynamic abnormalities on echocardiography (significant atrial enlargement, decreased contractility), the patient, in order to prevent the risk of sudden cardiac death, underwent implantation of single chamber pacemaker in VVIR mode and bipolar ventricular lead. Anticoagulant therapy was prescribed. After 6-month follow-up, relief of HF symptoms and an increase in left ventricular contractile function was noted.Discussion. Timely diagnosis and implantation of pacemakers allowed avoiding AAT and minimizing the HF symptoms. Continuous ventricular pacing and anticoagulant therapy are important in HF prevention.

Sick sinus syndrome (SSS) is a group of disorders characterized by an abnormal cardiac impulse formation or propagation from the sinoatrial node. Mutated SCN5A has been reported in SSS, however, homozygosity of SCN5A is exceedingly rare. Here, we report a consanguineous family with four affected children with SSS. Symptomatic bradycardia necessitated implanting a pacemaker in all of them. Sequencing SCN5A revealed a novel homozygous variant (p.Cys1850Arg), which was predicted to interfere with protein folding. Our report describes the phenotype of a novel homozygous SCN5A variant and contributes to the compendium of molecular pathology of inherited arrhythmias in consanguineous populations. [ABSTRACT FROM AUTHOR]

Introduction: Atrial standstill is a rare cardiac arrhythmia, which may present with different clinical symptoms, including longstanding dyspnea, congestive heart failure, syncope, cerebrovascular accidents, and even sudden cardiac death. According to such various presentations, diagnosis of atrial standstill may be complicated despite a high level of suspicion. Case Presentation: The present report demonstrated a case of bilateral idiopathic atrial standstill in a young female patient. The initial presentation of the disorder was the prolonged history of dyspnea and reduced effort tolerance, which was complicated by an episode of ischemic stroke two years ago. The patient was discharged with oral anticoagulants and anti-convulsants, but she had discontinued medication arbitrarily and was diagnosed in an electrophysiological study prior to pacemaker placement because of the junctional rhythm and premature ventricular beats. She was finally diagnosed as a case of biatrial standstill, which was characterized by the absence of electrical and mechanical activity in both atrias. Single-chamber permanent pacemaker was successfully implanted and she was discharged with oral anticoagulants and was recommended for further evaluation for idiopathic or familial cardiomyopathy. Conclusions: Atrial standstill could present in a silent manner as longstanding dyspnea and reduced effort tolerance, and remain misdiagnosed even after the development of cerebral ischemia in the absence of a high level of suspicion. These patients are eligible to receive oral anticoagulants life-long, and implanting PPM is almost indicated. [ABSTRACT FROM AUTHOR]

A 15-year-old donkey gelding was referred to the Equine Clinic of the Freie Universität Berlin because of acute onset of anorexia, bradycardia and multiple syncopes. The clinical examination revealed an irregular heartbeat (11-18 bpm) and syncopes. A continuous ECG revealed absence of P-waves and an irregular ventricular escape rhythm. An echocardiography revealed a pericardial effusion with reduction of left and right ventricular function. Laboratory abnormalities revealed increased troponin I, alpha hydroxybutyrate dehydrogenase and symmetric as well as asymmetric dimethylarginine. Increased concentrations of the cardiac glycoside digitoxin was evident in serum. Clinical findings were consistent with myocarditis with pericardial effusion and atrial standstill. Because of increasing severity of symptoms and grave prognosis the donkey was humanely euthanized. Histopathological examination of the cardiac atria including the sinoatrial node revealed severe, subacute, diffuse, suppurative myocarditis. [ABSTRACT FROM AUTHOR]

Competing Interests: The authors report no conflicts of interest for the published content. No funding information was provided.

Abstract Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome. [ABSTRACT FROM AUTHOR]

Background: Atrial standstill is an arrhythmogenic condition characterized by the absence of spontaneous electrical and mechanical atrial activity or in response to stimulation. There are few reported familial cases which have been associated with SCN5A mutations cosegregating with GJA5 or RYR2; however, isolated SCN5Amutations are rare.Objective: The purpose of this study was to determine the clinical and biophysical consequence of a novel SCN5A mutation identified in a family with progressive atrial standstill and sudden death.Methods: The family of a sporadic case of congenital atrial standstill underwent genetic screening. Human Embryonic Kidney 293 cells were transfected with wild-type (WT) or mutant SCN5A cDNAs. Biophysical properties were studied using whole-cell using patch clamp methods.Results: A novel homozygous SCN5A mutation, p.V1340L, was identified in the proband and her sister. The proband had complete atrial standstill whereas the sister had partial atrial standstill. Heterozygous mutations were identified in the mother, father, and brother. All three had normalsinus rhythm and were asymptomatic. The mutant Nav1.5(V1340L) reduced Nav1.5 current density as well as showed a depolarizing shift in the voltage-dependent steady-state activation(WT:-35.3±1.62mV;V1340L:-22.4±2.59mV;P=0.001).Conclusions: A homozygous loss-of-function SCN5A mutation likely results in atrial standstill and sudden death due to suppression of initiation of action potential. [ABSTRACT FROM AUTHOR]

Objective: To characterize the cardiac phenotype associated with the novel pathogenic variant (c.1526del) of LMNA gene, which we identified in a large, six-generation family., Methods and Results: A family tree was constructed. The clinical data of living and deceased family members were collected. DNA samples from 7 family members were analyzed for LMNA mutations using whole-exome high-throughput sequencing technology. The clinical presentation of pathogenic variant carriers was evaluated. In this six-generation family ( n  = 67), one member experienced sudden death at the age of 40-years-old. Three pathogenic variant carriers were identified to possess a novel heterozygous deletion mutation in LMNA gene (HGVS: NM_170707.4, c.1526del) located at exon 9 of LMNA chr1:156137145, which creates a premature translational stop signal (p.Pro509Leufs*39) in the LMNA gene and results in an mutant lamin A protein product. The main symptoms of the pathogenic variant carriers were palpitation, fatigue, and syncope, which typically occurred around 20-years-old. AV-conduction block and non-sustained ventricular tachycardia were the first signs of disease and would rapidly progress to atrial standstill around 30-years-old. Significant right atrial enlargement and bicuspid aortic valve malformation was also commonly seen in patients who carried this pathogenic variant., Conclusion: The pathogenic variant of c.1526del p.P509Lfs*39 was a frameshift deletion located at exon 9 of LMNA chr1:156137145 and causes severe right atrial enlargement, sick sinus syndrome, atrial standstill, ventricular tachycardia, and bicuspid aortic valve malformation. Our findings expand the phenotypic spectrum of novel LMNA gene mutations., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Ning, Han, Qiu, Hong, Xia, Liu and Liu.)

Despite advances in device closure for atrial septal defect, post-closure heart failure remains a clinical problem in adult patients but is seen only rarely in children. An eight-year-old boy, who had been followed by a local pediatrician with the diagnosis of diabetes mellitus and congenital heart disease, was consulted to us for cardiac re-evaluation. Electrocardiography demonstrated absent P waves, and echocardiography revealed enlargement of the right ventricle and both atria and secundum atrial septal defect. With the diagnosis of atrial standstill, secundum atrial septal defect and thiamine-responsive megaloblastic anemia, acute heart failure developed after transvenous closure of the atrial septal defect, which improved dramatically with thiamine and supportive treatment.

Background: The arrhythmogenesis of ventricular myocardial ischemia has been extensively studied, but models of atrial ischemia in humans are lacking. This study aimed at describing the electrophysiological alterations induced by acute atrial ischemia secondary to atrial coronary branch occlusion during elective coronary angioplasty.Methods and Results: Clinical data, 12-lead ECG, 12-hour Holter recordings, coronary angiography, and serial plasma levels of high-sensitivity troponin T and midregional proatrial natriuretic peptide were prospectively analyzed in 109 patients undergoing elective angioplasty of right or circumflex coronary arteries. Atrial coronary branches were identified and after the procedure patients were allocated into two groups: atrial branch occlusion (ABO, n=17) and atrial branch patency (non-ABO, n=92). In comparison with the non-ABO, patients with ABO showed: (1) higher incidence of periprocedural myocardial infarction (20% versus 53%, P=0.01); (2) more frequent intra-atrial conduction delay (19% versus 46%, P=0.03); (3) more marked PR segment deviation in the Holter recordings; and (4) higher incidence of atrial tachycardia (15% versus 41%, P=0.02) and atrial fibrillation (0% versus 12%, P=0.03). After adjustment by a propensity score, ABO was an independent predictor of periprocedural infarction (odds ratio, 3.4; 95% confidence interval, 1.01-11.6, P<0.05) and atrial arrhythmias (odds ratio, 5.1; 95% confidence interval, 1.2-20.5, P=0.02).Conclusions: Selective atrial coronary artery occlusion during elective percutaneous transluminal coronary angioplasty is associated with myocardial ischemic damage, atrial arrhythmias, and intra-atrial conduction delay. Our data suggest that atrial ischemic episodes might be considered as a potential cause of atrial fibrillation in patients with chronic coronary artery disease. [ABSTRACT FROM AUTHOR]

Two young Labrador retriever dogs with bradycardia-induced syncope resulting from atrial myopathy underwent permanent transvenous pacemaker implantation. Both dogs developed heart failure 3–5 years after pacemaker implantation. Both were managed medically for approximately 7 years after pacemaker implantation and, ultimately, were humanely euthanized due to refractory heart failure signs and quality of life concerns. Long-term management of dogs with atrial myopathy and secondary atrial standstill with pacemaker implantation and medical therapy for heart failure is feasible and prognosis may be better than previously reported or speculated. [ABSTRACT FROM AUTHOR]

Although sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact, the putative mechanism linking the 2 remain unclear. Although SND is accompanied by atrial myocardial structural changes in the right atrium, atrial fibrillation (AF) is a disease of variable interactions between left atrial triggers and substrate most commonly of left atrial origin. Significant advances have been made in our understanding of the genetic and pathophysiologic mechanism underlying the development and progression of SND and AF. Although some patients manifest SND as a result of electric remodeling induced by periods of AF, others develop progressive atrial structural remodeling that gives rise to both conditions together. The treatment strategy will thus vary according to the predominant disease phenotype. Although catheter ablation will benefit patients with predominantly AF and secondary SND, cardiac pacing may be the mainstay of therapy for patients with predominant fibrotic atrial cardiomyopathy. This contemporary review summarizes current knowledge on sinus node pathophysiology with the broader goal of yielding insights into the complex relationship between sinus node disease and atrial arrhythmias. [ABSTRACT FROM AUTHOR]

Aims: Atrial standstill is characterized by the absence of atrial activity. We report about a series of cases, in which conventional atrial pacemaker lead implantation in patients with symptomatic sinus node disease failed due to lack of excitable right atrial tissue, thus, prompting the diagnosis of atrial standstill. We hypothesized that mapping of the atria with subsequent identification of myocardium still amenable to atrial pacing would allow dual chamber pacemaker implantation.Methods and Results: In four patients, atrial lead implantation failed. In these patients, spontaneous or fibrillatory electrical activity was absent but the atria could not be captured despite high stimulation voltages at conventional atrial sites. We suspected partial or complete atrial standstill and subsequently confirmed this hypothesis by conventional (n = 1) or electroanatomical mapping (n = 3). Areas of fibrotic tissue were present in all patients as identified by lack of spontaneous electrical activity and inability of local electrical capture via the mapping catheter. Surviving atrial tissue, which could be electrically captured with subsequent conduction of activity to the atrioventricular (AV) node, was present in three patients. Successful targeted atrial lead implantation at these sites was achieved in all these patients. Isolated sinus node activity without conduction to the atria was found in one patient.Conclusion: Partial atrial standstill may be present and prevent atrial lead implantation in patients with sinus node disease. In these patients, recognition of partial atrial standstill and identification of surviving muscular islets with connection to the AV node by mapping studies may still allow synchronous AV sequential pacing. [ABSTRACT FROM AUTHOR]

Background: Atrial standstill (AS) is a rare condition characterized by absence of electrical activity within the atria. Studies to date have been limited., Objectives: The authors sought to describe the clinical characteristics, genetics, and outcomes of patients with AS., Methods: This was a retrospective multicenter study of patients <18 years at AS diagnosis, defined as absence of atrial activity documented during an electrophysiology study, device placement, or noninvasive rhythm tracings and confirmed by echocardiogram. Patients with acquired disorders were excluded. Clinical details and genetic variants were recorded and analyzed., Results: Twenty patients were diagnosed at a median age of 6.6 years (IQR: 2.9-10.8 years). Arrhythmias included 16 (80%) with atrial/supraventricular arrhythmias and 8 (40%) with ventricular tachycardia, including 4 with cardiac arrests. A type 1 Brugada pattern was documented in 4. Pacemakers were implanted in 18 (90%). Although atrial leads were attempted in 15, only 4 achieved pacing at implantation. During a median follow-up of 6.9 years (IQR: 1.2-13.3 years), 7 (35%) had thromboembolic events. Of these, none had atrial pacing, 6 were not on anticoagulation, and 1 was on aspirin. Genetic testing identified SCN5A variants in 13 patients (65%). Analyses suggest SCN5A loss-of-function may be one mechanism driving AS. Ventricular arrhythmias and cardiac arrest were more commonly seen in patients with biallelic SCN5A variants., Conclusions: AS may be associated with loss-of-function SCN5A variants. Patients demonstrate atrial and ventricular arrhythmias, and may present challenges during device placement. Patients without the capacity for atrial pacing are at risk for thromboembolic events and warrant anticoagulation., Competing Interests: Funding Support and Author Disclosures Dr Miyake is supported by National Heart, Lung, and Blood Institute grant K23HL136932. Dr Chiang is supported by the Leducq Foundation and a National Institutes of Health T32 grant from the National Human Genome Research Institute (#1T32HG010464). The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Electrocardiographic changes (ECG) are a common complication of acute pancreatitis (AP), although their etiology and pathogenesis remain unclear. Commonly reported electrocardiographic changes in human beings with AP include non-specific changes of the ventricular repolarisation process, and various kinds of conduction and/or rhythm anomalies. The association between AP and ECG abnormalities has not been investigated in the veterinary literature. We report a case of a previously healthy Japanese Chin dog with acute pancreatitis demonstrating severe bradycardia, ST-segment depression, atrial standstill, 2nd and then 3rd degree atrioventricular block, all of which were resolved once the pancreatitis ameliorated. We conclude that due to the transient nature of such ECG findings in patients with AP, as long as haemodynamics remain or can be maintained stable, decisions regarding permanent pacemaker therapy or euthanasia should be made with caution. [ABSTRACT FROM AUTHOR]

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Atrial dilatation and atrial standstill are etiologically heterogeneous phenotypes with poorly defined nosology. In 1983, we described 8-years follow-up of atrial dilatation with standstill evolution in 8 patients from 3 families. We later identified 5 additional patients with identical phenotypes: 1 member of the largest original family and 4 unrelated to the 3 original families. All families are from the same geographic area in Northeast Italy.We followed up the 13 patients for up to 37 years, extended the clinical investigation and monitoring to living relatives, and investigated the genetic basis of the disease. The disease was characterized by: (1) clinical onset in adulthood; (2) biatrial dilatation up to giant size; (3) early supraventricular arrhythmias with progressive loss of atrial electric activity to atrial standstill; (4) thromboembolic complications; and (5) stable, normal left ventricular function and New York Heart Association functional class during the long-term course of the disease. By linkage analysis, we mapped a locus at 1p36.22 containing the Natriuretic Peptide Precursor A gene. By sequencing Natriuretic Peptide Precursor A, we identified a homozygous missense mutation (p.Arg150Gln) in all living affected individuals of the 6 families. All patients showed low serum levels of atrial natriuretic peptide. Heterozygous mutation carriers were healthy and demonstrated normal levels of atrial natriuretic peptide.Autosomal recessive atrial dilated cardiomyopathy is a rare disease associated with homozygous mutation of the Natriuretic Peptide Precursor A gene and characterized by extreme atrial dilatation with standstill evolution, thromboembolic risk, preserved left ventricular function, and severely decreased levels of atrial natriuretic peptide. [ABSTRACT FROM AUTHOR]

Atrial septal defects of the ostium secundum variety are typically asymptomatic in infancy and early childhood. Congestive heart failure (CHF) may occur in the presence of significant mitral valve disease, pulmonary artery hypertension, or other diseases that lead to elevated filling pressures of the ventricles. Atrial standstill, a rare disease, was the probable cause of CHF in the 3-year-old child discussed in this report. [ABSTRACT FROM AUTHOR]