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1.
Methods Mol Biol ; 2320: 111-119, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34302653

RESUMO

Induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) have been shown to have great potential to play a key role in investigating cardiac diseases in vitro. Multielectrode array (MEA) system is sometimes preferable to patch-clamp in electrophysiological experiments in terms of several advantages. Here we show our protocol of electrophysiological examinations using MEA.


Assuntos
Bioensaio/métodos , Células-Tronco Pluripotentes Induzidas/citologia , Miócitos Cardíacos/citologia , Análise Serial de Tecidos/métodos , Células Cultivadas , Fenômenos Eletrofisiológicos/fisiologia , Humanos , Técnicas de Patch-Clamp/métodos
2.
Methods Mol Biol ; 2320: 121-133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34302654

RESUMO

Electrophysiological analysis of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) using a patch-clamp technique enables the most precise evaluation of electrophysiological properties in single cells. Compared to multielectrode array (MEA) and membrane voltage imaging, patch-clamp recordings offer quantitative measurements of action potentials, and the relevant ionic currents which are essential for the research of disease modeling of inherited arrhythmias, safety pharmacology, and drug discovery using hiPSC-CMs. In this chapter, we describe the detail flow of patch-clamp recordings in hiPSC-CMs.


Assuntos
Fenômenos Eletrofisiológicos/fisiologia , Células-Tronco Pluripotentes Induzidas/citologia , Miócitos Cardíacos/citologia , Técnicas de Patch-Clamp/métodos , Análise Serial de Tecidos/métodos , Potenciais de Ação/fisiologia , Arritmias Cardíacas/terapia , Células Cultivadas , Humanos
3.
Circ J ; 85(3): 323-329, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33518695

RESUMO

Due to the COVID-19 pandemic, the 84thAnnual Meeting of the Japanese Circulation Society (JCS) was held in a web-based format for the first time in its history as "The Week for JCS 2020" from Monday, July 27 to Sunday, August 2, 2020. All sessions, including general abstracts, were streamed live or on-demand. The main theme of the meeting was "Change Practice!" and the aim was to organize the latest findings in the field of cardiovascular medicine and discuss how to change practice. The total number of registered attendees was over 16,800, far exceeding our expectations, and many of the sessions were viewed by far more people than at conventional face-to-face scientific meetings. At this conference, the power of online information dissemination was fully demonstrated, and the evolution of online academic meetings will be a direction that cannot be reversed in the future. The meeting was completed with great success, and we express our heartfelt gratitude to all affiliates for their enormous amount of work, cooperation, and support.


Assuntos
Cardiologia/organização & administração , Congressos como Assunto/organização & administração , Sociedades Científicas/organização & administração , Telecomunicações/organização & administração , Cardiologia/tendências , Doenças Cardiovasculares/diagnóstico por imagem , Doenças Cardiovasculares/terapia , Congressos como Assunto/estatística & dados numéricos , Congressos como Assunto/tendências , Humanos , Japão , Pesquisa , Inquéritos e Questionários , Telecomunicações/estatística & dados numéricos , Telecomunicações/tendências
5.
J Thromb Thrombolysis ; 51(3): 779-788, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32728908

RESUMO

There are uncertainties on the influence of the days of diagnosis in a week (weekends versus weekdays) on clinical outcomes in patients with acute venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT). The COMMAND VTE registry is a multicenter cohort study enrolling 3027 consecutive patients with acute symptomatic VTE. The current study population consisted of 337 patients diagnosed on weekends and 2690 patients diagnosed on weekdays. We compared the clinical characteristics, management strategies and 30-day outcomes between the 2 groups. The patients diagnosed on weekends more often presented with PE (72% vs. 55%, P < 0.001), and with more severe hemodynamic condition for PE patients. The patients diagnosed on weekends more often received initial parenteral anticoagulation therapy and thrombolysis than those diagnosed on weekdays. The cumulative 30-day incidence of all-cause death was not significantly different between the two groups among PE patients (diagnosis on weekends: 6.2% vs. diagnosis on weekdays: 6.5%, P = 0.87), as well as among DVT patients (0.0% vs. 1.5%, P = 0.24). The most frequent cause of deaths was fatal PE in both groups among PE patients. The risks for recurrent VTE and major bleeding at 30-day were not significantly different between the 2 groups among PE patients, nor among DVT only patients. In conclusion, the VTE patients diagnosed on weekends presented more often with PE, and with more severe condition for PE patients. Nevertheless, the risk for 30-day mortality was not significantly different between patients diagnosed on weekends and on weekdays.

6.
Genet Med ; 23(1): 47-58, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32893267

RESUMO

PURPOSE: Stringent variant interpretation guidelines can lead to high rates of variants of uncertain significance (VUS) for genetically heterogeneous disease like long QT syndrome (LQTS) and Brugada syndrome (BrS). Quantitative and disease-specific customization of American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines can address this false negative rate. METHODS: We compared rare variant frequencies from 1847 LQTS (KCNQ1/KCNH2/SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data and developed disease-specific criteria for ACMG/AMP evidence classes-rarity (PM2/BS1 rules) and case enrichment of individual (PS4) and domain-specific (PM1) variants. RESULTS: Rare SCN5A variant prevalence differed between European (20.8%) and Japanese (8.9%) BrS patients (p = 5.7 × 10-18) and diagnosis with spontaneous (28.7%) versus induced (15.8%) Brugada type 1 electrocardiogram (ECG) (p = 1.3 × 10-13). Ion channel transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterized by high enrichment of case variants and >95% probability of pathogenicity. Applying the customized rules, 17.4% of European BrS and 74.8% of European LQTS cases had (likely) pathogenic variants, compared with estimated diagnostic yields (case excess over gnomAD) of 19.2%/82.1%, reducing VUS prevalence to close to background rare variant frequency. CONCLUSION: Large case-control data sets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.


Assuntos
Síndrome de Brugada , Síndrome do QT Longo , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/epidemiologia , Arritmias Cardíacas/genética , Síndrome de Brugada/genética , Testes Genéticos , Humanos , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/epidemiologia , Síndrome do QT Longo/genética , Mutação , Controle da População
7.
Int J Cardiol ; 323: 168-174, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-32877757

RESUMO

BACKGROUND: T-wave inversion (TWI) is not considered useful for diagnosing pediatric arrhythmogenic right ventricular cardiomyopathy (ARVC), because right precordial TWI in ARVC resembles a normal juvenile pattern. OBJECTIVES: The aims of this study were to clarify the electrocardiographic (ECG) characteristics of pediatric ARVC to distinguish those patients from healthy children. METHODS: Between 1979 and 2017, 11 ARVC patients under 18 years old were registered and compared with school screening ECGs from 48,401 healthy children. RESULTS: The mean age at the first arrhythmic event or diagnosis was 13.3 ± 4.7 years. Nine patients were asymptomatic initially and were found by ECG screening, but 6 developed severe symptoms during the follow-up. Healthy children had a normal juvenile pattern, while ARVC children, especially symptomatic patients, had a significant tendency to have inferior and anterior TWI. The phenomenon of T-wave discontinuity (TWD) in which the TWI became deeper from V1 to V3 and suddenly turned positive in V5 was significantly more frequent in ARVC (60%) than healthy children (0.55%). Anterior TWI and TWD were also significantly more frequent in those who developed severe symptoms. The sensitivity and specificity of TWD were 60% (95% CI, 31-83%), and 99% (95% CI, 99-99%) to distinguish ARVC from healthy children, as well as 100% (95% CI, 71-100%) and 80% (95% CI, 51-80%), respectively, to predict severe symptoms in the future. CONCLUSIONS: The ECG is useful to distinguish ARVC children, even in the early phase. Anterior TWI and TWD could detect ARVC children and to predict the possible serious conditions.


Assuntos
Displasia Arritmogênica Ventricular Direita , Adolescente , Arritmias Cardíacas , Displasia Arritmogênica Ventricular Direita/diagnóstico , Criança , Eletrocardiografia , Humanos , Sensibilidade e Especificidade
8.
J Cardiol ; 77(4): 395-403, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33218901

RESUMO

BACKGROUND: The majority of acute pulmonary embolism (PE) is caused by thrombus developed from leg veins. However, impact of concomitant deep venous thrombosis (DVT) on clinical outcomes has not been fully evaluated in patients with acute PE. METHODS: The COMMAND VTE Registry is a multicenter registry enrolling consecutive 3027 patients with acute symptomatic venous thromboembolism (VTE) in Japan. The current study population consisted of 655 acute PE patients who underwent lower extremities ultrasound examination at diagnosis for the assessment of concomitant DVT status. RESULTS: There were 424 patients with proximal DVT (64.7%), 162 patients with distal DVT (24.7%), and 69 patients with no DVT (10.5%). The cumulative 90-day incidence of all-cause death was higher in proximal DVT patients than in distal DVT and no DVT patients (7.9%, 2.5%, and 1.4%, p = 0.01). Regarding the causes of death, the cumulative 90-day incidence of PE-related death was low, and not significantly different across the 3 groups (1.4%, 0.6%, and 1.7%, p = 0.62). The most frequent cause of death was cancer in proximal and distal DVT patients. There were no significant differences in 90-day rates of recurrent VTE and major bleeding, regardless of the status of concomitant DVT (2.9%, 3.2%, and 2.2%, p = 0.79, and 1.5%, 4.4%, and 4.9%, p = 0.46, respectively). CONCLUSIONS: Acute PE with proximal DVT at diagnosis was associated with a higher risk for short-term mortality than in patients without DVT, while the risk for short-term mortality was not significantly different between distal DVT patients and patients without DVT.

9.
Circ J ; 84(11): 2006-2014, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33012736

RESUMO

BACKGROUND: Patients with cancer-associated venous thromboembolism (VTE) are at high risk for recurrent VTE and are recommended to receive prolonged anticoagulation therapy if they are at a low risk for bleeding. However, there are no established risk factors for bleeding during anticoagulation therapy.Methods and Results:The COMMAND VTE Registry is a multicenter retrospective registry enrolling 3,027 consecutive patients with acute symptomatic VTE among 29 Japanese centers. The present study population consisted of 592 cancer-associated VTE patients with anticoagulation therapy. We constructed a multivariable Cox proportional hazard model to estimate the hazard ratio (HR) and 95% confidence interval (CI) of the potential risk factors for major bleeding. During a median follow-up period of 199 days, major bleeding occurred in 72 patients. The cumulative incidence of major bleeding was 5.8% at 3 months, 13.8% at 1 year, 17.5% at 2 years, and 28.1% at 5 years. The most frequent major bleeding site was gastrointestinal tract (47%). Terminal cancer (adjusted HR, 4.17; 95% CI, 2.22-7.85, P<0.001), chronic kidney disease (adjusted HR, 1.89; 95% CI 1.06-3.37, P=0.031), and gastrointestinal cancer (adjusted HR, 1.78; 95% CI, 1.04-3.04, P=0.037) were independently associated with an increased risk of major bleeding. CONCLUSIONS: Major bleeding events were common during anticoagulation therapy in real-world cancer-associated VTE patients. Terminal cancer, chronic kidney disease, and gastrointestinal cancer were the independent risk factors for major bleeding.

12.
Artigo em Inglês | MEDLINE | ID: mdl-32936022

RESUMO

Background - Mutation/variant-site specific risk stratification in long-QT syndrome type 1 (LQT1) has been well investigated, but it is still challenging to adapt current enormous genomic information to clinical aspects caused by each mutation/variant. We assessed a novel variant-specific risk stratification in LQT1 patients. Methods - We classified a pathogenicity of 141 KCNQ1 variants among 927 LQT1 patients (536 probands) based on the American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP) guidelines and evaluated whether the ACMG/AMP-based classification was associated with arrhythmic risk in LQT1 patients. Results - Among 141 KCNQ1 variants, 61 (43.3%), 55 (39.0%), and 25 (17.7%) variants were classified into pathogenic (P), likely pathogenic (LP), and variant of unknown significance (VUS), respectively. Multivariable analysis showed that proband (HR = 2.53; 95%CI = 1.94-3.32; p <0.0001), longer QTc (≥500ms) (HR = 1.44; 95%CI = 1.13-1.83; p = 0.004), variants at membrane spanning (MS) (vs. those at N/C terminus) (HR = 1.42; 95%CI = 1.08-1.88; p = 0.01), C-loop (vs. N/C terminus) (HR = 1.52; 95%CI = 1.06-2.16; p = 0.02), and P variants [(vs. LP) (HR = 1.72; 95%CI = 1.32-2.26; p <0.0001), (vs. VUS) (HR = 1.81; 95%CI = 1.15-2.99; p = 0.009)] were significantly associated with syncopal events. The ACMG/AMP-based KCNQ1 evaluation was useful for risk stratification not only in family members but also in probands. A clinical score (0~4) based on proband, QTc (≥500ms), variant location (MS or C-loop) and P variant by ACMG/AMP guidelines allowed identification of patients more likely to have arrhythmic events. Conclusions - Comprehensive evaluation of clinical findings and pathogenicity of KCNQ1 variants based on the ACMG/AMP-based evaluation may stratify arrhythmic risk of congenital long-QT syndrome type 1.

13.
Front Cell Dev Biol ; 8: 761, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32903469

RESUMO

Background: Long QT syndrome type 3 (LQT3) is caused by gain-of-function mutations in the SCN5A gene, which encodes the α subunit of the cardiac voltage-gated sodium channel. LQT3 patients present bradycardia and lethal arrhythmias during rest or sleep. Further, the efficacy of ß-blockers, the drug used for their treatment, is uncertain. Recently, a large multicenter LQT3 cohort study demonstrated that ß-blocker therapy reduced the risk of life-threatening cardiac events in female patients; however, the detailed mechanism of action remains unclear. Objectives: This study aimed to establish LQT3-human induced pluripotent stem cells (hiPSCs) and to investigate the effect of propranolol in this model. Method: An hiPSCs cell line was established from peripheral blood mononuclear cells of a boy with LQT3 carrying the SCN5A-N1774D mutation. He had suffered from repetitive torsades de pointes (TdPs) with QT prolongation since birth (QTc 680 ms), which were effectively treated with propranolol, as it suppressed lethal arrhythmias. Furthermore, hiPSCs were differentiated into cardiomyocytes (CMs), on which electrophysiological functional assays were performed using the patch-clamp method. Results: N1774D-hiPSC-CMs exhibited significantly prolonged action potential durations (APDs) in comparison to those of the control cells (N1774D: 440 ± 37 ms vs. control: 272 ± 22 ms; at 1 Hz pacing; p < 0.01). Furthermore, N1774D-hiPSC-CMs presented gain-of-function features: a hyperpolarized shift of steady-state activation and increased late sodium current compared to those of the control cells. 5 µM propranolol shortened APDs and inhibited late sodium current in N1774D-hiPSC-CMs, but did not significantly affect in the control cells. In addition, even in the presence of intrapipette guanosine diphosphate ßs (GDPßs), an inhibitor of G proteins, propranolol reduced late sodium current in N1774D cells. Therefore, these results suggested a unique inhibitory effect of propranolol on late sodium current unrelated to ß-adrenergic receptor block in N1774D-hiPSC-CMs. Conclusion: We successfully recapitulated the clinical phenotype of LQT3 using patient-derived hiPSC-CMs and determined that the mechanism, by which propranolol inhibited the late sodium current, was independent of ß-adrenergic receptor signaling pathway.

14.
Circ Genom Precis Med ; 13(5): 435-443, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32818388

RESUMO

BACKGROUND: LMNA is a known causative gene of dilated cardiomyopathy and familial conduction disturbance. Nonsense-mediated mRNA decay, normally caused by nonsense mutations, is a safeguard process to protect cells from deleterious effects of inappropriate proteins from mutated genes. Nonsense-mediated mRNA decay induced by nonstop codon mutations is rare. We investigated the effect of an LMNA missense mutation identified in 2 families affected by cardiac laminopathy. METHODS: Genomic DNA and total RNA were isolated from patients' peripheral blood lymphocytes or cardiac tissue. LMNA-coding exons were screened by direct sequencing. Complementary DNAs were generated by a reverse transcription-polymerase chain reaction from total RNA. Quantitative polymerase chain reaction was performed to quantify the LMNA complementary DNA amount by using specific primers for lamins A and C. A minigene splicing reporter experiment was performed to assess the effect of detected variants on RNA splicing. The protein expressions of both isoforms were analyzed by Western blotting. RESULTS: We detected a missense variant c.936 G>C (p. Q312H) at the end of exon 5 of LMNA by genomic DNA sequencing in 2 unrelated families affected by dilated cardiomyopathy and cardiac conduction disturbance. This variant was previously reported in a French family suffering from muscular dystrophy and cardiac conduction disturbance. Sequencing of complementary DNA demonstrated that the mutated allele was absent. By quantitative polymerase chain reaction assay, we confirmed a 90% reduction in LMNA complementary DNA. The minigene splicing reporter assay demonstrated a splicing error by the variant. Western blot analysis revealed that lamin A and C expressions were reduced far >50%. CONCLUSIONS: We report an LMNA missense mutation found in 2 families, which disrupted a normal splicing site, led to nonsense-mediated mRNA decay, and resulted in severe cardiac laminopathy.

15.
J Hum Genet ; 65(12): 1083-1091, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32681117

RESUMO

Mutations in KCNQ1, KCNH2, and SCN5A are the major cause of long QT syndrome (LQTS). More than 90% of the genotyped patients have been reported to carry mutations in any of these three genes. Thanks to increasing popularity of next generation sequencer (NGS), novel CACNA1C mutations have been identified among LQTS patients without extra-cardiac phenotypes. We aimed to clarify the frequency of genotypes in LQTS patients in the era of NGS. The study comprised 160 congenital LQTS patients (71 males) registered from November 2015 to September 2018. Inclusion criteria was QTc > 460 ms and Schwartz score ≥ 3. We performed genetic analysis using target gene method by NGS and confirmed the mutations by Sanger method. The median age for genetic screening was 13 (0-68) years. Sixteen patients suffered cardiac arrest, 47 syncope, and 97 were asymptomatic. We identified genetic mutations in 111 (69.4%) patients including 6 CACNA1C (5.4% of the genotyped patients) with 4 asymptomatic patients. Five (3.1%) patients carried double mutations; three out of them with RYR2 and KCNQ1 or KCNH2. In conclusion, CACNA1C screening would be recommended even if the patient is asymptomatic to elucidate the genetic background of the LQTS patients.


Assuntos
Canais de Cálcio Tipo L/genética , Predisposição Genética para Doença , Canal de Potássio KCNQ1/genética , Síndrome do QT Longo/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Canal de Potássio ERG1/genética , Feminino , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Recém-Nascido , Síndrome do QT Longo/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Linhagem , Adulto Jovem
16.
Pacing Clin Electrophysiol ; 43(8): 838-846, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32588437

RESUMO

BACKGROUND: Telethonin (TCAP) is a Z-disk protein that maintains cytoskeletal integrity and various signaling pathways in cardiomyocytes. TCAP is shown to modulate α-subunit of the human cardiac sodium channel (hNav 1.5) by direct interactions. Several TCAP variants are found in cardiomyopathies. We sought to investigate whether TCAP variants are associated with arrhythmia syndromes. METHODS: Mutational analyses for TCAP were performed in 303 Japanese patients with Brugada syndrome, arrhythmogenic right ventricular cardiomyopathy, and J-wave pattern ECG. Using patch-clamp techniques, electrophysiological characteristics of hNav 1.5 were studied in HEK-293 cells stably expressing hNav 1.5 and transiently transfected with wild-type (WT) or variant TCAP. RESULTS: We identified two TCAP variants, c.145G>A:p.E49K and c.458G>A:p.R153H, in four individuals. p.E49K was found in two patients with ARVC or BrS. p.R153H was found in two patients with BrS or J-wave pattern ECG. No patient had variant hNav 1.5. Patch-clamp experiments demonstrated that peak sodium currents were significantly reduced in cells expressing p.R153H and p.E49K compared with WT-TCAP (66%, p.R153H; 72%, p.E49K). Voltage dependency of peak IV curve was rightward-shifted by 5 mV in cells expressing p.E49K compared with WT-TCAP. Voltage dependency of activation was not leftward-shifted by p.R153H, while voltage dependency of steady-state inactivation was leftward-shifted by p.E49K. CONCLUSIONS: We found two TCAP variants in the patients with BrS, J-wave pattern ECG, and ARVC that can cause loss-of-function of the hNav 1.5 in heterologous expression systems. Our observation suggests that these variants might impair INa and be associated with the patients' electrophysiological phenotypes. Further studies linking our experimental data to clinical phenotypes are warranted.

18.
Thromb Res ; 191: 66-75, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32402995

RESUMO

INTRODUCTION: The external validation of the modified Ottawa score to predict the risk of recurrence in patients with cancer-associated venous thromboembolism (VTE) has not yet been firmly established. The present study aimed to evaluate the utility and limitations of the modified Ottawa score in the risk stratification of recurrent VTE in patients with cancer-associated VTE. MATERIALS AND METHODS: The COMMAND VTE Registry is a multicenter retrospective registry enrolling 3027 consecutive patients with acute symptomatic VTE among 29 Japanese centers. The present study population consisted of 614 cancer-associated VTE patients, who were divided into 3 groups; High-risk group: 202 patients (33%) with a modified Ottawa score ≥ 1, Intermediate-risk group: 269 patients (44%) with a score = 0, and Low-risk group: 143 patients (23%) with a score ≤ -1. RESULTS: Recurrent VTE occurred in 39 patients on anticoagulation therapy within 6 months. The cumulative incidence of recurrent VTE substantially increased in the higher risk categories by the modified Ottawa score (high-risk group: 13.6% [95%CI, 8.9%-20.2%], intermediate-risk group: 5.9% [95%CI, 3.5%-9.8%], and low-risk group: 3.0% [95%CI, 1.1%-7.8%], P = .02). The discriminating power of the score was modest with a C-statistic of 0.63. Each score component of the score had a different impact on recurrent events with a variable effect size. CONCLUSIONS: The risks of recurrence in patients with cancer-associated VTE substantially increased in the higher risk categories by using the modified Ottawa score, but the discriminating power of the score for recurrence was modest with a variable impact of each score component on recurrent events.


Assuntos
Neoplasias , Tromboembolia Venosa , Anticoagulantes/uso terapêutico , Humanos , Neoplasias/complicações , Recidiva , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Tromboembolia Venosa/etiologia
19.
Pacing Clin Electrophysiol ; 43(5): 456-461, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32323320

RESUMO

BACKGROUND: Short-coupled variant of torsades de pointes (scTdP) is a disease characterized by TdP without QT prolongation, which is initiated by extremely short-coupled ventricular extra-systoles. Its genetic background remains rarely unveiled. OBJECTIVE: We aimed to identify genetic variations in patients with scTdP and to analyze the functional change of the mutant Na+ channel identified in a scTdP patient. METHODS AND RESULTS: We performed genetic analysis for inherited arrhythmia-related 45 genes using next-generation sequencer (MiSeq, Illumina) among seven consecutive scTdP patients. We identified an SCN5A mutation R800H in a 38-year-old male who suffered ventricular fibrillation during dinner and was resuscitated. Two months later, he lost his consciousness at work. His Holter electrocardiogram showed scTdP. He had no family history of sudden cardiac death or heart disease. Functional analysis of the SCN5A-R800H channels showed a significantly shortened recovery time from inactivation. Peak sodium current densities in SCN5A-R800H were larger than those in wild type but the difference was not statistically significant. CONCLUSIONS: We identified an SCN5A mutation in a scTdP patient and confirmed that the mutant channel caused the shortness of recovery time from inactivation. SCN5A might be a candidate gene for scTdP.


Assuntos
Canal de Sódio Disparado por Voltagem NAV1.5/genética , Torsades de Pointes/genética , Adulto , Eletrocardiografia Ambulatorial , Feminino , Humanos , Masculino , Mutação , Torsades de Pointes/fisiopatologia
20.
Circ J ; 84(4): 559-568, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32161207

RESUMO

BACKGROUND: Long QT syndrome type 8 (LQT8) is a rare genotype of long QT syndrome. Late-appearing T-waves (LaT) are often documented in patients with LQT8, as in long QT syndrome type 3 (LQT3); however, the frequency of LaT and its relevance to the clinical severity of LQT8 remains unclear. This study investigated T-wave morphology (TWM) in LQT3 and LQT8 patients and compared the phenotypes of different TWMs.Methods and Results:TWMs were classified into 3 types: early onset T-waves (EoT), LaT, and bifid T-waves (biT). Electrocardiogram (ECG) measurements, symptoms, and topology were compared among TWM types. The study cohort comprised 25 patients with LQT8 (14 mutations) and 25 patients with LQT3 (14 mutations). LaT was detected in 17 (68%) and 13 (52%) LQT8 and LQT3 patients, respectively. There were no significant differences in ECG measurements or the severity of symptoms between patients with LaT and those with other TWMs in either the LQT8 or LQT3 group. However, only patients with LaT experienced cardiopulmonary arrest. Compared with the LQT3 group, in the LQT8 group there was a tendency for mutations in patients with LaT to be located in domain-linking regions. CONCLUSIONS: In this study, two-thirds of patients with LQT8 exhibited LaT on ECG, and nearly one-third of those experienced cardiopulmonary arrest. Further investigations are warranted to differentiate between LQT3 and LQT8 in patients exhibiting LaT to optimize therapy.


Assuntos
Potenciais de Ação , Transtorno Autístico/diagnóstico , Eletrocardiografia , Sistema de Condução Cardíaco/fisiopatologia , Frequência Cardíaca , Síndrome do QT Longo/diagnóstico , Sindactilia/diagnóstico , Adolescente , Adulto , Transtorno Autístico/complicações , Transtorno Autístico/genética , Transtorno Autístico/fisiopatologia , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Parada Cardíaca/etiologia , Parada Cardíaca/fisiopatologia , Humanos , Lactente , Recém-Nascido , Japão , Síndrome do QT Longo/complicações , Síndrome do QT Longo/genética , Síndrome do QT Longo/fisiopatologia , Masculino , Fenótipo , Valor Preditivo dos Testes , Índice de Gravidade de Doença , Sindactilia/complicações , Sindactilia/genética , Sindactilia/fisiopatologia , Fatores de Tempo , Adulto Jovem
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