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Journal of Comparative Pathology Oct 2020The hearts of three dogs, clinically diagnosed as having persistent atrial standstill syndrome (PAS), were studied post mortem. The most significant gross findings in...
The hearts of three dogs, clinically diagnosed as having persistent atrial standstill syndrome (PAS), were studied post mortem. The most significant gross findings in the hearts of all three dogs were dilatation and marked reduction in the thickness of both atrial walls. Histopathologically, all three had widespread progressive loss of the atrial myocardium with replacement by fatty or fibrofatty tissue, consistent with atrial myopathy. The lesion mainly affected the upper half of both atria and was more severe in the epimyocardium and midmyocardium than in the endomyocardium. On the basis of these observations, it is proposed that the atrial myopathy commences in the upper regions of both atria and progresses downwards, as has been demonstrated electrophysiologically in PAS in humans, and extends from the epicardium towards the endocardium.
Topics: Animals; Cardiomyopathies; Dog Diseases; Dogs; Genetic Diseases, Inborn; Heart Atria; Heart Block
PubMed: 33222880
DOI: 10.1016/j.jcpa.2020.08.005 -
Annals of Noninvasive Electrocardiology... Mar 2017Atrial standstill is a rare disorder of cardiac rhythm that is characterized by total absence of electrical activity in one or both atria. We report herein the case of a...
Atrial standstill is a rare disorder of cardiac rhythm that is characterized by total absence of electrical activity in one or both atria. We report herein the case of a patient with atrial fibrillation and symptomatic 4.0 s pauses who received a ventricular demand pacemaker. The patient later underwent mitral valve replacement with a pericardial tissue valve and the Cox-maze III procedure for symptomatic mitral stenosis and atrial fibrillation. Following surgery, he developed atrial standstill and became pacemaker dependent. The pacemaker was later revised to an atrioventricular sequential pacemaker. Twelve hours after revision, atrioventricular sequential pacing was noted and mechanical function of the atria was confirmed by Doppler echocardiography.
Topics: Atrial Fibrillation; Cardiomyopathies; Echocardiography, Doppler; Electrocardiography; Genetic Diseases, Inborn; Heart Atria; Heart Block; Heart Valve Prosthesis; Heart Valve Prosthesis Implantation; Humans; Male; Middle Aged; Mitral Valve Stenosis; Pacemaker, Artificial; Postoperative Complications
PubMed: 27558131
DOI: 10.1111/anec.12399 -
Japanese Circulation Journal Jun 1996Acute infectious myocarditis is primarily by viruses and bacteria, but sometimes by rickettsia. Tsutsugamushi disease is a febrile illness caused by Rickettsia...
Acute infectious myocarditis is primarily by viruses and bacteria, but sometimes by rickettsia. Tsutsugamushi disease is a febrile illness caused by Rickettsia tsutsugamushi, and has been prevalent in Korea since 1985. Characteristics of tsutsugamushi disease are fever, rash and eschar. Tsutsugamushi myocarditis is rare. Cardiac involvement may include ST-T changes, PR prolongation, mild mitral regurgitation, and perivascular inflammation with myocardial necrosis. We describe here a 50-year-old woman who complained of fever, orthopnea and chest pain. Work-up of the patient revealed abdominal scar, positive tsutsugamushi antibody, congestive heart failure with severe mitral and tricuspid regurgitation, persistent atrial standstill on electrophysiologic study, junctional rhythm and ST-T changes mimicking anterior myocardial infarction and myocardial inflammation with perivasculitis on endomyocardial biopsy. The patient's condition improved with doxycycline and inotropics. Persistent atrial standstill during was found at the one-year follow-up.
Topics: Arrhythmias, Cardiac; Atrial Function; Female; Heart Atria; Heart Conduction System; Heart Failure; Humans; Middle Aged; Myocarditis
PubMed: 8844306
DOI: 10.1253/jcj.60.382 -
Frontiers in Cell and Developmental... 2020Voltage-gated sodium (Na) channels are transmembrane proteins that initiate and propagate neuronal and cardiac action potentials. Na channel β subunits have been widely...
Voltage-gated sodium (Na) channels are transmembrane proteins that initiate and propagate neuronal and cardiac action potentials. Na channel β subunits have been widely studied due to their modulatory role. Mice null for , which encodes Na β1 and β1b subunits, have defects in neuronal development and excitability, spontaneous generalized seizures, cardiac arrhythmias, and early mortality. A mutation in exon 3 of , c.308A>T leading to β1_p.D103V and β1b_p.D103V, was previously found in a patient with a history of proarrhythmic conditions with progressive atrial standstill as well as cognitive and motor deficits accompanying structural brain abnormalities. We investigated whether β1 or β1b subunits carrying this mutation affect Na1.5 and/or Na1.1 currents using a whole cell patch-clamp technique in tsA201 cells. We observed a decrease in sodium current density in cells co-expressing Na1.5 or Na1.1 and β1 compared to β1. Interestingly, β1b did not affect Na1.1 sodium current density but induced a positive shift in the voltage dependence of inactivation and a faster recovery from inactivation compared to β1b. The β1b isoform did not affect Na1.5 current properties. Although the _c.308A>T mutation may not be the sole cause of the patient's symptoms, we observed a clear loss of function in both cardiac and brain sodium channels. Our results suggest that the mutant β1 and β1b subunits play a fundamental role in the observed electrical dysfunction.
PubMed: 33134290
DOI: 10.3389/fcell.2020.528742 -
HeartRhythm Case Reports May 2023
PubMed: 37324960
DOI: 10.1016/j.hrcr.2023.02.009 -
Journal of the American College of... Jul 2017Inherited cardiac conduction disease is a rare bradyarrhythmia associated with mutations in various genes that affect action potential propagation. It is often...
BACKGROUND
Inherited cardiac conduction disease is a rare bradyarrhythmia associated with mutations in various genes that affect action potential propagation. It is often characterized by isolated conduction disturbance of the His-Purkinje system, but it is rarely described as a syndromic form.
OBJECTIVES
The authors sought to identify the genetic defect in families with a novel bradyarrhythmia syndrome associated with bone malformation.
METHODS
The authors genetically screened 15 European cases with genotype-negative de novo atrioventricular (AV) block and their parents by trio whole-exome sequencing, plus 31 Japanese cases with genotype-negative familial AV block or sick sinus syndrome by targeted exon sequencing of 457 susceptibility genes. Functional consequences of the mutation were evaluated using an in vitro cell expression system and in vivo knockout mice.
RESULTS
The authors identified a connexin-45 (Cx45) mutation (p.R75H) in 2 unrelated families (a de novo French case and a 3-generation Japanese family) who presented with progressive AV block, which resulted in atrial standstill without ventricular conduction abnormalities. Affected individuals shared a common extracardiac phenotype: a brachyfacial pattern, finger deformity, and dental dysplasia. Mutant Cx45 expressed in Neuro-2a cells showed normal hemichannel assembly and plaque formation. However, Lucifer yellow dye transfer and gap junction conductance between cell pairs were severely impaired, which suggested that mutant Cx45 impedes gap junction communication in a dominant-negative manner. Tamoxifen-induced, cardiac-specific Cx45 knockout mice showed sinus node dysfunction and atrial arrhythmia, recapitulating the intra-atrial disturbance.
CONCLUSIONS
Altogether, the authors showed that Cx45 mutant p.R75H is responsible for a novel disease entity of progressive atrial conduction system defects associated with craniofacial and dentodigital malformation.
Topics: Adolescent; Adult; Animals; Atrioventricular Block; Child; Child, Preschool; Connexins; DNA; DNA Mutational Analysis; Dentofacial Deformities; Disease Models, Animal; Disease Progression; Electrocardiography; Female; Humans; Male; Mice; Mice, Transgenic; Middle Aged; Mutation; Pedigree; Phenotype; Young Adult
PubMed: 28705318
DOI: 10.1016/j.jacc.2017.05.039 -
The Journal of Tehran Heart Center 2011We introduce a 32-year-old man who was evaluated for a dizziness and headache of unknown origin for at least two months and was referred to our center after ECG...
We introduce a 32-year-old man who was evaluated for a dizziness and headache of unknown origin for at least two months and was referred to our center after ECG findings. He was finally diagnosed as a case of idiopathic, familial, diffuse, persistent atrial standstill, which is a rare arrhythmogenic condition characterized by the absence of electrical and mechanical activity in the atria. He successfully received a single-chamber permanent pacemaker.
PubMed: 23074623
DOI: No ID Found -
Frontiers in Physiology 2013Slowed myocardial conduction velocity (θ) is associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. θ is determined by the ion...
Slowed myocardial conduction velocity (θ) is associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. θ is determined by the ion channel and physical properties of cardiac myocytes and by their interconnections. Thus, θ is closely related to the maximum rate of action potential (AP) depolarization [(dV/dt)max], as determined by the fast Na(+) current (I Na); the axial resistance (r a) to local circuit current flow between cells; their membrane capacitances (c m); and to the geometrical relationship between successive myocytes within cardiac tissue. These determinants are altered by a wide range of pathophysiological conditions. Firstly, I Na is reduced by the impaired Na(+) channel function that arises clinically during heart failure, ischemia, tachycardia, and following treatment with class I antiarrhythmic drugs. Such reductions also arise as a consequence of mutations in SCN5A such as those occurring in Lenègre disease, Brugada syndrome (BrS), sick sinus syndrome, and atrial fibrillation (AF). Secondly, r a, may be increased due to gap junction decoupling following ischemia, ventricular hypertrophy, and heart failure, or as a result of mutations in CJA5 found in idiopathic AF and atrial standstill. Finally, either r a or c m could potentially be altered by fibrotic change through the resultant decoupling of myocyte-myocyte connections and coupling of myocytes with fibroblasts. Such changes are observed in myocardial infarction and cardiomyopathy or following mutations in MHC403 and SCN5A resulting in hypertrophic cardiomyopathy (HCM) or Lenègre disease, respectively. This review defines and quantifies the determinants of θ and summarizes experimental evidence that links changes in these determinants with reduced myocardial θ and arrhythmogenesis. It thereby identifies the diverse pathophysiological conditions in which abnormal θ may contribute to arrhythmia.
PubMed: 23825462
DOI: 10.3389/fphys.2013.00154 -
Turk Kardiyoloji Dernegi Arsivi : Turk... Oct 2013Despite 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....
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.
Topics: Anemia, Megaloblastic; Cardiomyopathies; Child; Genetic Diseases, Inborn; Heart Atria; Heart Block; Heart Failure; Heart Septal Defects, Atrial; Humans; Male; Thiamine
PubMed: 24164997
DOI: 10.5543/tkda.2013.63295 -
Journal of the American College of... Aug 1991Persistent atrial standstill is a very rare pathophysiologic condition whose diagnosis is established when both electrical and mechanical silence of the atria are... (Comparative Study)
Comparative Study
Persistent atrial standstill is a very rare pathophysiologic condition whose diagnosis is established when both electrical and mechanical silence of the atria are confirmed. To test the hypothesis that secretion of atrial natriuretic peptide is disturbed in patients with persistent atrial standstill, the response of atrial natriuretic peptide secretion and other neurohormonal factors during exercise was investigated in three patients with a rate-responsive ventricular demand (VVI) pacemaker implanted for confirmed persistent atrial standstill. The results were compared with those observed in eight normal subjects and patients with a rate-responsive VVI (Group A) or atrial demand (AAI) (Group B) pacemaker implanted for confirmed sick sinus syndrome. Patients in Group A displayed significant elevation of alpha-human atrial natriuretic peptide secretion both before and during exercise (122.5 +/- 14.8 and 207.5 +/- 8.3 pg/ml, respectively) compared with those in Group B (55 +/- 14.1 and 116.4 +/- 51.5 pg/ml, respectively) and the normal subjects (18.9 +/- 9.8 and 30.8 +/- 19.2 pg/ml, respectively). This indicated development of a nonphysiologic increase in atrial volume or pressure overload, or both, in rate-responsive VVI pacing because of lack of atrioventricular synchrony. However, patients with persistent atrial standstill had undetectable (less than 10 pg/ml) or almost undetectable secretion of atrial natriuretic peptide as well as lower levels of cyclic guanosine monophosphate in the circulation both before and during exercise. Changes in plasma catecholamines during exercise were similar in patients with persistent atrial standstill compared with the other groups. This study indicates that "endocrinologic silence" accompanies electrical and mechanical silence of the atria, which may constitute a third diagnostic clue to persistent atrial standstill.
Topics: Adult; Aged; Arrhythmias, Cardiac; Atrial Function; Atrial Natriuretic Factor; Cyclic AMP; Cyclic GMP; Electrocardiography; Epinephrine; Exercise; Exercise Test; Female; Heart Atria; Humans; Male; Middle Aged; Norepinephrine; Pacemaker, Artificial; Sick Sinus Syndrome
PubMed: 1649852
DOI: 10.1016/0735-1097(91)90601-5