RESUMEN
The first symptoms of catecholaminergic polymorphic ventricular tachycardia (CPVT) usually occur in childhood and adolescence. 60% of patients experience syncope before the age of 40. Sudden cardiac death (SCD) is the first symptom of the disease in 30-50% of patients with CPVT. Early diagnosis is therefore crucial for the patient's prognosis. The diagnosis of CPVT is confirmed by a normal resting ECG, exclusion of structural heart disease, detection of bidirectional or polymorphic ventricular tachycardia (VT) in the stress ECG and/or detection of a pathogenic mutant in a gene associated with CPVT. Up to 60% of CPVT patients carry changes in the RYR2 gene. This gene encodes the cardiac ryanodine receptor, the most important Ca2+-releasing channel of the sarcoplasmic reticulum, which plays a central role in the contraction and relaxation of the heart muscle. If the function of the ryanodine receptor is impaired, too much calcium enters the cells, which triggers life-threatening arrhythmias. The overactive ryanodine receptor is therefore the main target for gene therapy methods. Even though the development of gene therapy is progressing, there is still no causal therapy available and it is all the more important to make a diagnosis as early as possible, which enables appropriate behavior and adequate symptomatic therapy. The decisive factor here is the evaluation of the genetic analysis in the context of the clinical findings. Based on this, recommendations can be made for preventive measures and the avoidance of specific triggers that could lead to life-threatening arrhythmias.
Asunto(s)
Muerte Súbita Cardíaca , Canal Liberador de Calcio Receptor de Rianodina , Taquicardia Ventricular , Humanos , Taquicardia Ventricular/genética , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/terapia , Muerte Súbita Cardíaca/etiología , Muerte Súbita Cardíaca/prevención & control , Canal Liberador de Calcio Receptor de Rianodina/genética , Adolescente , Niño , Electrocardiografía , Adulto , Pronóstico , Adulto JovenRESUMEN
Calmodulin (CaM) is a ubiquitous, small cytosolic calcium (Ca2+)-binding sensor that plays a vital role in many cellular processes by binding and regulating the activity of over 300 protein targets. In cardiac muscle, CaM modulates directly or indirectly the activity of several proteins that play a key role in excitation-contraction coupling (ECC), such as ryanodine receptor type 2 (RyR2), l-type Ca2+ (Cav1.2), sodium (NaV1.5) and potassium (KV7.1) channels. Many recent clinical and genetic studies have reported a series of CaM mutations in patients with life-threatening arrhythmogenic syndromes, such as long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). We recently showed that four arrhythmogenic CaM mutations (N98I, D132E, D134H, and Q136P) significantly reduce the binding of CaM to RyR2. Herein, we investigate in vivo functional effects of these CaM mutations on the normal zebrafish embryonic heart function by microinjecting complementary RNA corresponding to CaMN98I, CaMD132E, CaMD134H, and CaMQ136P mutants. Expression of CaMD132E and CaMD134H mutants results in significant reduction of the zebrafish heart rate, mimicking a severe form of human bradycardia, whereas expression of CaMQ136P results in an increased heart rate mimicking human ventricular tachycardia. Moreover, analysis of cardiac ventricular rhythm revealed that the CaMD132E and CaMN98I zebrafish groups display an irregular pattern of heart beating and increased amplitude in comparison to the control groups. Furthermore, circular dichroism spectroscopy experiments using recombinant CaM proteins reveals a decreased structural stability of the four mutants compared to the wild-type CaM protein in the presence of Ca2+. Finally, Ca2+-binding studies indicates that all CaM mutations display reduced CaM Ca2+-binding affinities, with CaMD132E exhibiting the most prominent change. Our data suggest that CaM mutations can trigger different arrhythmogenic phenotypes through multiple and complex molecular mechanisms.
Asunto(s)
Arritmias Cardíacas , Calmodulina , Pez Cebra , Animales , Calmodulina/metabolismo , Calmodulina/genética , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Mutación , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismo , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Mutación Missense , Taquicardia Ventricular/genética , Taquicardia Ventricular/metabolismo , Calcio/metabolismoRESUMEN
BACKGROUND AND AIMS: Pathogenic desmoplakin (DSP) gene variants are associated with the development of a distinct form of arrhythmogenic cardiomyopathy known as DSP cardiomyopathy. Patients harbouring these variants are at high risk for sustained ventricular arrhythmia (VA), but existing tools for individualized arrhythmic risk assessment have proven unreliable in this population. METHODS: Patients from the multi-national DSP-ERADOS (Desmoplakin SPecific Effort for a RAre Disease Outcome Study) Network patient registry who had pathogenic or likely pathogenic DSP variants and no sustained VA prior to enrolment were followed longitudinally for the development of first sustained VA event. Clinically guided, step-wise Cox regression analysis was used to develop a novel clinical tool predicting the development of incident VA. Model performance was assessed by c-statistic in both the model development cohort (n = 385) and in an external validation cohort (n = 86). RESULTS: In total, 471 DSP patients [mean age 37.8 years, 65.6% women, 38.6% probands, 26% with left ventricular ejection fraction (LVEF) < 50%] were followed for a median of 4.0 (interquartile range: 1.6-7.3) years; 71 experienced first sustained VA events {2.6% [95% confidence interval (CI): 2.0, 3.5] events/year}. Within the development cohort, five readily available clinical parameters were identified as independent predictors of VA and included in a novel DSP risk score: female sex [hazard ratio (HR) 1.9 (95% CI: 1.1-3.4)], history of non-sustained ventricular tachycardia [HR 1.7 (95% CI: 1.1-2.8)], natural logarithm of 24-h premature ventricular contraction burden [HR 1.3 (95% CI: 1.1-1.4)], LVEF < 50% [HR 1.5 (95% CI: .95-2.5)], and presence of moderate to severe right ventricular systolic dysfunction [HR 6.0 (95% CI: 2.9-12.5)]. The model demonstrated good risk discrimination within both the development [c-statistic .782 (95% CI: .77-.80)] and external validation [c-statistic .791 (95% CI: .75-.83)] cohorts. The negative predictive value for DSP patients in the external validation cohort deemed to be at low risk for VA (<5% at 5 years; n = 26) was 100%. CONCLUSIONS: The DSP risk score is a novel model that leverages readily available clinical parameters to provide individualized VA risk assessment for DSP patients. This tool may help guide decision-making for primary prevention implantable cardioverter-defibrillator placement in this high-risk population and supports a gene-first risk stratification approach.
Asunto(s)
Desmoplaquinas , Humanos , Desmoplaquinas/genética , Femenino , Masculino , Medición de Riesgo/métodos , Adulto , Persona de Mediana Edad , Arritmias Cardíacas/genética , Heterocigoto , Taquicardia Ventricular/genéticaRESUMEN
Long QT Syndrome type 8 (LQT8) is a cardiac arrhythmic disorder associated with Timothy Syndrome, stemming from mutations in the CACNA1C gene, particularly the G406R mutation. While prior studies hint at CACNA1C mutations' role in ventricular arrhythmia genesis, the mechanisms, especially in G406R presence, are not fully understood. This computational study explores how the G406R mutation, causing increased transmural dispersion of repolarization, induces and sustains reentrant ventricular arrhythmias. Using three-dimensional numerical simulations on an idealized left-ventricular model, integrating the Bidomain equations with the ten Tusscher-Panfilov ionic model, we observe that G406R mutation with 11% and 50% heterozygosis significantly increases transmural dispersion of repolarization. During S1-S4 stimulation protocols, these gradients facilitate conduction blocks, triggering reentrant ventricular tachycardia. Sustained reentry pathways occur only with G406R mutation at 50% heterozygosis, while neglecting transmural heterogeneities of action potential duration prevents stable reentry, regardless of G406R mutation presence.
Asunto(s)
Potenciales de Acción , Canales de Calcio Tipo L , Simulación por Computador , Síndrome de QT Prolongado , Sindactilia , Humanos , Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/fisiopatología , Canales de Calcio Tipo L/genética , Sindactilia/genética , Sindactilia/fisiopatología , Mutación , Trastorno Autístico/genética , Trastorno Autístico/fisiopatología , Ventrículos Cardíacos/fisiopatología , Modelos Cardiovasculares , Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatología , Taquicardia Ventricular/genética , Taquicardia Ventricular/fisiopatologíaRESUMEN
Genetic arrhythmia disorders are rare diseases; however, they are a common cause of sudden cardiac death in children, adolescents, and young adults. In principle, a distinction can be made between channelopathies and cardiomyopathies in the context of genetic diseases. This paper focuses on the channelopathies long and short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT). Early diagnosis of these diseases is essential, as drug therapy, behavioral measures, and if necessary, implantation of a cardioverter defibrillator can significantly improve the prognosis and quality of life of patients. This paper highlights the pathophysiological and genetic basis of these channelopathies, describes their clinical manifestations, and comments on the principles of diagnosis, risk stratification and therapy.
Asunto(s)
Arritmias Cardíacas , Síndrome de Brugada , Canalopatías , Humanos , Arritmias Cardíacas/genética , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Arritmias Cardíacas/fisiopatología , Canalopatías/genética , Canalopatías/diagnóstico , Canalopatías/terapia , Síndrome de Brugada/genética , Síndrome de Brugada/diagnóstico , Síndrome de Brugada/fisiopatología , Síndrome de Brugada/terapia , Taquicardia Ventricular/genética , Taquicardia Ventricular/terapia , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatología , Adolescente , Niño , Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/diagnóstico , Síndrome de QT Prolongado/terapia , Síndrome de QT Prolongado/fisiopatología , Muerte Súbita Cardíaca/prevención & control , Muerte Súbita Cardíaca/etiología , Adulto , Desfibriladores Implantables , ElectrocardiografíaRESUMEN
Cardiac ryanodine receptor (RyR2) gain-of-function mutations cause catecholaminergic polymorphic ventricular tachycardia (CPVT). Conversely, RyR2 loss-of-function mutations cause a new disease entity, termed calcium release deficiency syndrome (CRDS), which may include RYR2-related long QT syndrome (LQTS). Importantly, unlike CPVT, patients with CRDS do not always exhibit exercise- or epinephrine-induced ventricular arrhythmias, which precludes a diagnosis of CRDS. Here we report a boy and his father, who both experienced exercise-induced cardiac events and harbor the same RYR2 E4107A variant. In the boy, an exercise stress test (EST) and epinephrine provocation test (EPT) did not induce any ventricular arrhythmias. QTc was slightly prolonged (QTc: 474 ms), and an EPT induced QTc prolongation (QTc-baseline: 466 ms, peak: 532 ms, steady-state: 527 ms). In contrast, in his father, QTc was not prolonged (QTc: 417 ms), and neither an EST nor EPT induced QTc prolongation. However, an EST induced multifocal premature ventricular contraction (PVC) bigeminy and bidirectional PVC couplets. Thus, they exhibited distinct clinical phenotypes: the boy exhibited LQTS (or CRDS) phenotype, whereas his father exhibited CPVT phenotype. These findings suggest that, in addition to the altered RyR2 function, other unidentified factors, such as other genetic, epigenetic, and environmental factors, and aging, may be involved in the diverse phenotypic manifestations. Considering that a single RYR2 variant can cause both CPVT and LQTS (or CRDS) phenotypes, in cascade screening of patients with CPVT and CRDS, an EST and EPT are not sufficient and genetic analysis is required to identify individuals who are at increased risk for life-threatening arrhythmias.
Asunto(s)
Síndrome de QT Prolongado , Fenotipo , Canal Liberador de Calcio Receptor de Rianodina , Taquicardia Ventricular , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Masculino , Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/diagnóstico , Taquicardia Ventricular/genética , Taquicardia Ventricular/diagnóstico , Electrocardiografía , Linaje , Adulto , Prueba de Esfuerzo , MutaciónRESUMEN
Pathogenic and likely pathogenic variants in the TECRL gene are known to be associated with recessive catecholaminergic polymorphic ventricular tachycardia 3, which can include prolonged QT intervals (MIM#614021). We report a case of cardiac arrest in a previously healthy adolescent male in the community. The patient was found to have a novel maternally inherited likely pathogenic variant in TECRL (c.915T>G [p.Tyr305Ter]) and an additional 19-kb duplication encompassing multiple exons of TECRL (chr4:65165944-65185287, dup [4q13.1]) not identified in the mother. Genetic results were revealed via rapid whole-genome sequencing, which allowed appropriate treatment and prognostication.
Asunto(s)
Taquicardia Ventricular , Humanos , Taquicardia Ventricular/genética , Masculino , Adolescente , Linaje , Mutación , Electrocardiografía , Predisposición Genética a la Enfermedad , Secuenciación Completa del GenomaRESUMEN
Bidirectional ventricular tachycardia is a unique arrhythmia that can herald lethal arrhythmia syndromes. Using cases based on real patient stories, this article examines 3 different presentations to help clinicians learn the differential diagnosis associated with this condition. Each associated genetic disorder will be briefly discussed, and valuable tips for distinguishing them from each other will be provided.
Asunto(s)
Taquicardia Ventricular , Niño , Humanos , Masculino , Arritmias Cardíacas/genética , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatología , Diagnóstico Diferencial , Electrocardiografía , Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/diagnóstico , Síndrome de QT Prolongado/fisiopatología , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/genética , Taquicardia Ventricular/fisiopatología , AdolescenteRESUMEN
BACKGROUND: Dexmedetomidine (DEX), a highly selective α2-adrenoceptor agonist, can decrease the incidence of arrhythmias, such as catecholaminergic polymorphic ventricular tachycardia (CPVT). However, the underlying mechanisms by which DEX affects cardiac electrophysiological function remain unclear. METHODS: Ryanodine receptor (RyR2) heterozygous R2474S mice were used as a model for CPVT. WT and RyR2R2474S/+ mice were treated with isoproterenol (ISO) and DEX, and electrocardiograms were continuously monitored during both in vivo and ex vivo experiments. Dual-dye optical mapping was used to explore the anti-arrhythmic mechanism of DEX. RESULTS: DEX significantly reduced the occurrence and duration of ISO-induced of VT/VF in RyR2R2474S/+ mice in vivo and ex vivo. DEX remarkably prolonged action potential duration (APD80) and calcium transient duration (CaTD80) in both RyR2R2474S/+ and WT hearts, whereas it reduced APD heterogeneity and CaT alternans in RyR2R2474S/+ hearts. DEX inhibited ectopy and reentry formation, and stabilized voltage-calcium latency. CONCLUSION: DEX exhibited an antiarrhythmic effect through stabilizing membrane voltage and intracellular Ca2+. DEX can be used as a beneficial perioperative anesthetic for patients with CPVT or other tachy-arrhythmias.
Asunto(s)
Arritmias Cardíacas , Calcio , Dexmedetomidina , Canal Liberador de Calcio Receptor de Rianodina , Animales , Dexmedetomidina/farmacología , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/genética , Calcio/metabolismo , Ratones , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/tratamiento farmacológico , Arritmias Cardíacas/genética , Potenciales de la Membrana/efectos de los fármacos , Isoproterenol/farmacología , Taquicardia Ventricular/metabolismo , Taquicardia Ventricular/genética , Taquicardia Ventricular/tratamiento farmacológico , Antiarrítmicos/farmacología , Masculino , Potenciales de Acción/efectos de los fármacos , Ratones Endogámicos C57BLAsunto(s)
Epilepsia Generalizada , Canal Liberador de Calcio Receptor de Rianodina , Taquicardia Ventricular , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Taquicardia Ventricular/genética , Taquicardia Ventricular/fisiopatología , Taquicardia Ventricular/diagnóstico , Epilepsia Generalizada/genética , Masculino , Femenino , MutaciónRESUMEN
Ryanodine receptor 2 (RyR2) is a large Ca2+-release channel in the sarcoplasmic reticulum (SR) of cardiac muscle cells. It serves to release Ca2+ from the SR into the cytosol to initiate muscle contraction. RyR2 overactivation is associated with arrhythmogenic cardiac disease, but few specific inhibitors have been reported so far. Here, we identified an RyR2-selective inhibitor 1 from the chemical compound library and synthesized it from glycolic acid. Synthesis of various derivatives to investigate the structure-activity relationship of each substructure afforded another two RyR2-selective inhibitors 6 and 7, among which 6 was the most potent. Notably, compound 6 also inhibited Ca2+ release in cells expressing the RyR2 mutants R2474S, R4497C and K4750Q, which are associated with cardiac arrhythmias such as catecholaminergic polymorphic ventricular tachycardia (CPVT). This inhibitor is expected to be a useful tool for research on the structure and dynamics of RyR2, as well as a lead compound for the development of drug candidates to treat RyR2-related cardiac disease.
Asunto(s)
Bloqueadores de los Canales de Calcio , Canal Liberador de Calcio Receptor de Rianodina , Humanos , Calcio/metabolismo , Relación Dosis-Respuesta a Droga , Descubrimiento de Drogas , Células HEK293 , Estructura Molecular , Canal Liberador de Calcio Receptor de Rianodina/efectos de los fármacos , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Relación Estructura-Actividad , Bloqueadores de los Canales de Calcio/química , Bloqueadores de los Canales de Calcio/farmacología , Antiarrítmicos/química , Antiarrítmicos/farmacología , Taquicardia Ventricular/tratamiento farmacológico , Taquicardia Ventricular/genéticaRESUMEN
In this case report, we describe a 14-year-old patient with a novel RyR2 gene mutation (c.6577G > T/p.Val2193Leu), identified through a comprehensive review of medical history, examination findings, and follow-up data. The pathogenic potential of this mutation, which results in the loss of some interatomic forces and compromises the closure of the RyR2 protein pore leading to calcium leakage, was analyzed using the I-TASSER Suite to predict the structural changes in the protein. This mutation manifested clinically as co-morbid catecholaminergic polymorphic ventricular tachycardia (CPVT) and benign epilepsy with centrotemporal spikes (BECTS), a combination not previously documented in the same patient. While seizures were successfully managed with levetiracetam, the patient's exercise-induced syncope episodes could not be controlled with metoprolol, highlighting the complexity and challenge in managing CPVT associated with this novel RyR2 variation.
Asunto(s)
Mutación , Canal Liberador de Calcio Receptor de Rianodina , Taquicardia Ventricular , Humanos , Canal Liberador de Calcio Receptor de Rianodina/genética , Taquicardia Ventricular/genética , Taquicardia Ventricular/tratamiento farmacológico , Adolescente , Masculino , Epilepsia Rolándica/genética , Epilepsia Rolándica/tratamiento farmacológico , ElectrocardiografíaRESUMEN
Arrhythmogenic cardiomyopathy is a non-ischaemic cardiomyopathy characterised by the presence of myocardial dysfunction and inherited conduction disease that predisposes patients to malignant ventricular arrhythmias and sudden cardiac death. There is a growing awareness of the diverse phenotypic presentation of arrhythmogenic cardiomyopathy, which may demonstrate preferential involvement of the left, right or both ventricles. A subset of arrhythmogenic cardiomyopathy may be due to mutations of desmosomes, intercellular junctions of the myocardium that promote structural and electrical integrity. Mutations of desmoplakin, encoded by the DSP gene and a critical constituent protein of desmosomes, have been implicated in the onset of arrhythmogenic cardiomyopathy. We present a structured case report of desmoplakin arrhythmogenic cardiomyopathy secondary to novel heterozygous DSP mutations (c.1061T>C and c.795G>C) manifesting as early onset non-ischaemic cardiomyopathy and recurrent ventricular tachycardia refractory to multiple modalities of therapy, including oral antiarrhythmics, cardiac ablation and bilateral sympathectomy, as well as frequent implantable cardioverter-defibrillator discharges.
Asunto(s)
Displasia Ventricular Derecha Arritmogénica , Cardiomiopatías , Taquicardia Ventricular , Humanos , Desmoplaquinas/genética , Displasia Ventricular Derecha Arritmogénica/complicaciones , Displasia Ventricular Derecha Arritmogénica/diagnóstico , Displasia Ventricular Derecha Arritmogénica/genética , Cardiomiopatías/complicaciones , Cardiomiopatías/genética , Cardiomiopatías/terapia , Miocardio/patología , Taquicardia Ventricular/genética , Taquicardia Ventricular/terapiaRESUMEN
AIMS: Dilated cardiomyopathy (DCM) with arrhythmic phenotype combines phenotypical aspects of DCM and predisposition to ventricular arrhythmias, typical of arrhythmogenic cardiomyopathy. The definition of DCM with arrhythmic phenotype is not universally accepted, leading to uncertainty in the identification of high-risk patients. This study aimed to assess the prognostic impact of arrhythmic phenotype in risk stratification and the correlation of arrhythmic markers with high-risk arrhythmogenic gene variants in DCM patients. METHODS AND RESULTS: In this multicentre study, DCM patients with available genetic testing were analysed. The following arrhythmic markers, present at baseline or within 1 year of enrolment, were tested: unexplained syncope, rapid non-sustained ventricular tachycardia (NSVT), ≥1000 premature ventricular contractions/24 h or ≥50 ventricular couplets/24 h. LMNA, FLNC, RBM20, and desmosomal pathogenic or likely pathogenic gene variants were considered high-risk arrhythmogenic genes. The study endpoint was a composite of sudden cardiac death and major ventricular arrhythmias (SCD/MVA). We studied 742 DCM patients (45 ± 14 years, 34% female, 410 [55%] with left ventricular ejection fraction [LVEF] <35%). During a median follow-up of 6 years (interquartile range 1.6-12.1), unexplained syncope and NSVT were the only arrhythmic markers associated with SCD/MVA, and the combination of the two markers carried a significant additive risk of SCD/MVA, incremental to LVEF and New York Heart Association class. The probability of identifying an arrhythmogenic genotype rose from 8% to 30% if both early syncope and NSVT were present. CONCLUSION: In DCM patients, the combination of early detected NSVT and unexplained syncope increases the risk of life-threatening arrhythmic outcomes and can aid the identification of carriers of malignant arrhythmogenic genotypes.
Asunto(s)
Cardiomiopatía Dilatada , Muerte Súbita Cardíaca , Fenotipo , Humanos , Femenino , Cardiomiopatía Dilatada/genética , Cardiomiopatía Dilatada/fisiopatología , Cardiomiopatía Dilatada/diagnóstico , Cardiomiopatía Dilatada/complicaciones , Masculino , Persona de Mediana Edad , Pronóstico , Muerte Súbita Cardíaca/epidemiología , Muerte Súbita Cardíaca/etiología , Adulto , Medición de Riesgo/métodos , Síncope/genética , Síncope/etiología , Síncope/fisiopatología , Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatología , Arritmias Cardíacas/diagnóstico , Volumen Sistólico/fisiología , Taquicardia Ventricular/genética , Taquicardia Ventricular/fisiopatología , Taquicardia Ventricular/diagnóstico , Pruebas Genéticas/métodosRESUMEN
INTRODUCTION: Arrhythmogenic cardiomyopathy (AC) is an inherited cardiomyopathy characterized by fibro-fatty replacement of cardiomyocytes, leading to life-threatening ventricular arrhythmia and heart failure. Pathogenic variants of desmoglein2 gene (DSG2) have been reported as genetic etiologies of AC. In contrast, many reported DSG2 variants are benign or variants of uncertain significance. Correct genetic variant classification is crucial for determining the best medical therapy for the patient and family members. METHODS: Pathogenicity of the DSG2 Ser194Leu variant that was identified by whole exome sequencing in a patient, who presented with ventricular tachycardia and was diagnosed with AC, was investigated by electron microscopy and immunohistochemical staining of endomyocardial biopsy sample. RESULTS: Electron microscopy demonstrated a widened gap in the adhering junction and a less well-organized intercalated disk region in the mutated cardiomyocytes compared to the control. Immunohistochemical staining in the proband diagnosed with AC showed reduced expression of desmoglein 2 and connexin 43 and intercalated disc distortion. Reduced expression of DSG2 and Connexin 43 were observed in cellular cytoplasm and gap junctions. Additionally, we detected perinuclear accumulation of DSG2 and Connexin 43 in the proband sample. CONCLUSION: Ser194Leu is a missense pathogenic mutation of DSG2 gene associated with arrhythmogenic left ventricular cardiomyopathy.
Asunto(s)
Displasia Ventricular Derecha Arritmogénica , Cardiomiopatías , Taquicardia Ventricular , Humanos , Conexina 43/genética , Conexina 43/metabolismo , Displasia Ventricular Derecha Arritmogénica/genética , Cardiomiopatías/complicaciones , Mutación/genética , Arritmias Cardíacas/complicaciones , Taquicardia Ventricular/genética , Taquicardia Ventricular/complicaciones , Miocitos Cardíacos/metabolismo , Desmogleína 2/genética , Desmogleína 2/metabolismoRESUMEN
FKBP12.6, a binding protein to the immunosuppressant FK506, which also binds the ryanodine receptor (RyR2) in the heart, has been proposed to regulate RyR2 function and to have antiarrhythmic properties. However, the level of FKBP12.6 expression in normal hearts remains elusive and some controversies still persist regarding its effects, both in basal conditions and during ß-adrenergic stimulation. We quantified FKBP12.6 in the left ventricles (LV) of WT (wild-type) mice and in two novel transgenic models expressing distinct levels of FKBP12.6, using a custom-made specific anti-FKBP12.6 antibody and a recombinant protein. FKBP12.6 level in WT LV was very low (0.16 ± 0.02 nmol/g of LV), indicating that <15% RyR2 monomers are bound to the protein. Mice with 14.1 ± 0.2 nmol of FKBP12.6 per g of LV (TG1) had mild cardiac hypertrophy and normal function and were protected against epinephrine/caffeine-evoked arrhythmias. The ventricular myocytes showed higher [Ca2+]i transient amplitudes than WT myocytes and normal SR-Ca2+ load, while fewer myocytes showed Ca2+ sparks. TG1 cardiomyocytes responded to 50 nM Isoproterenol increasing these [Ca2+]i parameters and producing RyR2-Ser2808 phosphorylation. Mice with more than twice the TG1 FKBP12.6 value (TG2) showed marked cardiac hypertrophy with calcineurin activation and more arrhythmias than WT mice during ß-adrenergic stimulation, challenging the protective potential of high FKBP12.6. RyR2R420Q CPVT mice overexpressing FKBP12.6 showed fewer proarrhythmic events and decreased incidence and duration of stress-induced bidirectional ventricular tachycardia. Our study, therefore, quantifies for the first time endogenous FKBP12.6 in the mouse heart, questioning its physiological relevance, at least at rest due its low level. By contrast, our work demonstrates that with caution FKBP12.6 remains an interesting target for the development of new antiarrhythmic therapies.
Asunto(s)
Canal Liberador de Calcio Receptor de Rianodina , Taquicardia Ventricular , Proteínas de Unión a Tacrolimus , Animales , Ratones , Adrenérgicos , Antiarrítmicos/farmacología , Cardiomegalia , Incidencia , Miocitos Cardíacos , Taquicardia Ventricular/genéticaRESUMEN
BACKGROUND: Although structural heart disease is frequently present among patients who experience sudden cardiac death (SCD), inherited arrhythmia syndromes can also play an important role in the occurrence of SCD. CPVT2, which is the second-most prevalent form of CPVT, arises from an abnormality in the CASQ2 gene. OBJECTIVE: We represent a novel CASQ2 variant that causes CPVT2 and conduct a comprehensive review on this topic. METHODS: The proband underwent Whole-exome sequencing (WES) in order to ascertain the etiology of CPVT. Subsequently, the process of segregating the available family members was carried out through the utilization of PCR and Sanger Sequencing. We searched the google scholar and PubMed/Medline for studies reporting CASQ2 variants, published up to May 10,2023. We used the following mesh term "Calsequestrin" and using free-text method with terms including "CASQ2","CASQ2 variants", and "CASQ2 mutation". RESULTS: The CASQ2 gene was found to contain an autosomal recessive nonsense variant c.268_269insTA:p.Gly90ValfsTer4, which was identified by WES. This variant was determined to be the most probable cause of CPVT in the pedigree under investigation. CONCLUSION: CASQ2 variants play an important role in pathogenesis of CPVT2. Notabely, based on results of our study and other findings in the literature the variant in this gene may cause an neurological signs in the patients with CPVT2. Further studies are needed for more details about the role of this gene in CPVT evaluation, diagnosis, and gene therapy.
Asunto(s)
Calsecuestrina , Taquicardia Ventricular , Niño , Femenino , Humanos , Masculino , Calsecuestrina/genética , Electrocardiografía , Secuenciación del Exoma , Corazón/fisiopatología , Linaje , Síncope/genética , Taquicardia Ventricular/genética , Codón sin Sentido/genética , MutaciónRESUMEN
Advances in the field of human genetics have led to an accumulating understanding of the genetic basis of distinct nonischemic cardiomyopathies associated with ventricular tachycardias (VTs) and sudden cardiac death. To date, there is an increasing proportion of patients with inherited cardiomyopathies requiring catheter ablation for VTs. This review provides an overview of disease-causing gene mutations frequently encountered and relevant for clinical electrophysiologists. Available data on VT ablation in patients with an inherited etiology and a phenotype of a nondilated left ventricular cardiomyopathy, dilated cardiomyopathy, or hypertrophic cardiomyopathy are summarized. VTs amenable to catheter ablation are related to nonischemic fibrosis. Recent insights into genotype-phenotype relations of subtype and location of fibrosis have important implications for treatment planning. Current strategies to delineate nonischemic fibrosis and related arrhythmogenic substrates using multimodal imaging, image integration, and electroanatomical mapping are provided. The ablation approach depends on substrate location and extension. Related procedural aspects including patient-tailored (enhanced) ablation strategies and outcomes are outlined. Challenging substrates for VT and the underlying inherited etiologies with a high risk for rapid progressive heart failure contribute to poor outcomes after catheter ablation. Electroanatomical data obtained during ablation may allow the identification of patients at particular risk who need to be considered for early work-up for left ventricular assist device implantation or heart transplantation.
Asunto(s)
Cardiomiopatías , Cardiomiopatía Dilatada , Ablación por Catéter , Taquicardia Ventricular , Humanos , Resultado del Tratamiento , Cardiomiopatías/complicaciones , Cardiomiopatías/genética , Taquicardia Ventricular/genética , Taquicardia Ventricular/cirugía , Cardiomiopatía Dilatada/complicaciones , Fibrosis , Ablación por Catéter/métodosRESUMEN
BACKGROUNDS: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare but lethal cardiac ion channelopathy. Delayed diagnosis and misdiagnosis remain a matter of concern due to its rarity and insufficient recognition of this disorder, particularly in developing countries like China. AIMS AND METHODS: We reported six catecholaminergic polymorphic ventricular tachycardia (CPVT) children diagnosed in our center along with a comprehensive review of Chinese pediatric CPVT patients reported in domestic and overseas literature between January 2013 and December 2021 to provide an essential reference for physicians to deepen their understanding of pediatric CPVT. RESULTS: A total of 95 children with CPVT, including our six patients from 21 medical centers were identified. The median age of symptom onset is 8.7 ± 3.0 years. Diagnosis occurred at a median age of 12.9 ± 6.8 years with a delay of 4.3 ± 6.6 years. Selective beta-blockers (Metoprolol and Bisoprolol) were prescribed for 38 patients (56.7%) and 29 (43.3%) patients received non-selective beta-blocker (Propranolol and Nadolol) treatment. Six patients accepted LCSD and seven received ICD implantation at the subsequent therapy. A total of 13 patients died during the disease course. Of the 67 patients with positive gene test results, variants in RYR2 were 47 (70.1%), CASQ2 were 11 (16.4%), and RYR2 accompanied SCN5A were 7 (10.4%). Patients with CASQ2 gene mutations presented with younger symptom onset age, higher positive family history rate and better prognosis than those with RYR2 mutations. CONCLUSION: Chinese pediatric patients with CPVT had a poorer prognosis than other cohorts, probably due to delayed/missed diagnosis, non-standard usage of beta-blockers, unavailability of flecainide, and a lower rate of LCSD and ICD implantation.