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Sodium voltage-gated channel α subunit 5 (SCN5A)-mutations may cause an array of arrhythmogenic syndromes most frequently as an autosomal dominant trait, with incomplete penetrance, variable expressivity and male predominance. In the present study, we retrospectively describe a group of Mexican patients with SCN5A-disease causing variants in whom the onset of symptoms occurred in the pediatric age range. The study included 17 patients with clinical diagnosis of primary electrical disease, at least one SCN5A pathogenic or likely pathogenic mutation and age of onset <18 years, and all available first- and second-degree relatives. Fifteen patients (88.2%) were male, and sixteen independent variants were found (twelve missense, three truncating and one complex inframe deletion/insertion). The frequency of compound heterozygosity was remarkably high (3/17, 17.6%), with early childhood onset and severe disease. Overall, 70.6% of pediatric patients presented with overlap syndrome, 11.8% with isolated sick sinus syndrome, 11.8% with isolated Brugada syndrome (BrS) and 5.9% with isolated type 3 long QT syndrome (LQTS). A total of 24/45 SCN5A mutation carriers were affected (overall penetrance 53.3%), and penetrance was higher in males (63.3%, 19 affected/30 mutation carriers) than in females (33.3%, 5 affected/15 carriers). In conclusion, pediatric patients with SCNA-disease causing variants presented mainly as overlap syndrome, with predominant loss-of-function phenotypes of sick sinus syndrome (SSS), progressive cardiac conduction disease (PCCD) and ventricular arrhythmias.

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The pandemic caused by the SARS-COV-2 or COVID-19 virus has been a global challenge given its high rate of transmission and lack of effective therapy or vaccine. This scenario has led to the use of various drugs that have demonstrated a potential effect against the virus in vitro. However, time has not been enough to properly evaluate their clinical effectiveness. The use of chloroquine/hydroxychloroquine, azithromycin and antiviral treatment and has been proposed by various groups, supported by in-vitro studies and limited patient series, without the adequate scientific rigor that precedes drug prescription. Although it may represent the only hope for many patients, it is important to know the main adverse effects associated with the use of these drugs and to better select patients who may benefit from them.

La pandemia por el virus SARS-COV-2 causante de la enfermedad COVID-19 representa un reto mundial dada su alta tasa de transmisión y ausencia de una terapia efectiva o vacuna. Este escenario ha propiciado el uso de diversos fármacos que in vitro han demostrado un potencial efecto contra el virus. Sin embargo, el tiempo no ha sido suficiente para evaluar su efectividad clínica con el adecuado rigor científico que precede a la prescripción de medicamentos. El uso de cloroquina/hidroxicloroquina, azitromicina y esquemas antivirales ha sido propuesto por diversos grupos, apoyado por series de pacientes limitada en número. Si bien puede representar la única esperanza para muchos enfermos, es importante conocer los principales efectos adversos asociados al uso de estas drogas y seleccionar mejor a los pacientes que puedan beneficiarse de ellas. El riesgo de arritmias ventriculares incrementa tanto por el uso de fármacos como por la gravedad de la propia enfermedad viral.

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Resumen La pandemia por el virus SARS-COV-2 causante de la enfermedad COVID-19 representa un reto mundial dada su alta tasa de transmisión y ausencia de una terapia efectiva o vacuna. Este escenario ha propiciado el uso de diversos fármacos que in vitro han demostrado un potencial efecto contra el virus. Sin embargo, el tiempo no ha sido suficiente para evaluar su efectividad clínica con el adecuado rigor científico que precede a la prescripción de medicamentos. El uso de cloroquina/hidroxicloroquina, azitromicina y esquemas antivirales ha sido propuesto por diversos grupos, apoyado por series de pacientes limitada en número. Si bien puede representar la única esperanza para muchos enfermos, es importante conocer los principales efectos adversos asociados al uso de estas drogas y seleccionar mejor a los pacientes que puedan beneficiarse de ellas. El riesgo de arritmias ventriculares incrementa tanto por el uso de fármacos como por la gravedad de la propia enfermedad viral.

Abstract The pandemic caused by the SARS-COV-2 or COVID-19 virus has been a global challenge given its high rate of transmission and lack of effective therapy or vaccine. This scenario has led to the use of various drugs that have demonstrated a potential effect against the virus in vitro. However, time has not been enough to properly evaluate their clinical effectiveness. The use of chloroquine/hydroxychloroquine, azithromycin and antiviral treatment and has been proposed by various groups, supported by in-vitro studies and limited patient series, without the adequate scientific rigor that precedes drug prescription. Although it may represent the only hope for many patients, it is important to know the main adverse effects associated with the use of these drugs and to better select patients who may benefit from them.

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La muerte súbita (MS) es un evento trágico que representa un grave problema de salud. Se estima que causa cerca de 4-5 millones de decesos por año en todo el mundo. La MS se define como la muerte ocurrida en el lapso de 1 h en una persona sin signos previos de fatalidad; puede denominarse «recuperada¼, cuando el paciente afectado sobrevive al episodio potencialmente fatal ya sea por reanimación cardiopulmonar o desfibrilación efectiva. Las canalopatías arritmogénicas son alteraciones funcionales de los canales iónicos del corazón, generalmente condicionados por mutaciones en los genes que los codifican y dan lugar a diversos tipos de arritmias que pueden culminar en MS, el deceso ocurre normalmente antes de los 40 años y el corazón en estudio de autopsia suele ser estructuralmente normal. En la presente revisión presentamos las principales causas de MS en el contexto del corazón estructuralmente normal y discutimos el abordaje que se debe dar a los pacientes y familiares de víctimas que han experimentado éste trágico evento.

Sudden death (SD) is a tragic event and a world-wide health problem. Every year, near 4-5 million people experience SD. SD is defined as the death occurred in 1 h after the onset of symptoms in a person without previous signs of fatality. It can be named «recovered SD¼ when the case received medical attention, cardiac reanimation effective defibrillation or both, surviving the fatal arrhythmia. Cardiac channelopathies are a group of diseases characterized by abnormal ion channel function due to genetic mutations in ion channel genes, providing increased susceptibility to develop cardiac arrhythmias and SD. Usually the death occurs before 40 years of age and in the autopsy the heart is normal. In this review we discuss the main cardiac channelopathies involved in sudden cardiac death along with current management of cases and family members that have experienced such tragic event.

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Sudden death (SD) is a tragic event and a world-wide health problem. Every year, near 4-5 million people experience SD. SD is defined as the death occurred in 1h after the onset of symptoms in a person without previous signs of fatality. It can be named "recovered SD" when the case received medical attention, cardiac reanimation effective defibrillation or both, surviving the fatal arrhythmia. Cardiac channelopathies are a group of diseases characterized by abnormal ion channel function due to genetic mutations in ion channel genes, providing increased susceptibility to develop cardiac arrhythmias and SD. Usually the death occurs before 40 years of age and in the autopsy the heart is normal. In this review we discuss the main cardiac channelopathies involved in sudden cardiac death along with current management of cases and family members that have experienced such tragic event.

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The long QT syndrome (LQTS) is a genetic disorder characterized by prolongation of the QT interval in the electrocardiogram (ECG) and a propensity to "torsades de pointes" ventricular tachycardia frequently leading to syncope, cardiac arrest, or sudden death usually in young otherwise healthy individuals. LQTS caused by mutations of predominantly potassium and sodium ion channel genes or channel-interacting proteins leading to positive overcharge of myocardial cell with consequent heterogeneous prolongation of repolarization in various layers and regions of myocardium. These conditions facilitate the early after-depolarization and reentry phenomena underlying development of polymorphic ventricular tachycardia observed in patients with LQTS. Obtaining detailed patient history regarding cardiac events in the patient and his/her family members combined with careful interpretation of standard 12-lead ECG (with precise measurement of QT interval in all available ECGs and evaluation of T-wave morphology) usually is sufficient to diagnose the syndrome. The LQTS show great genetic heterogeneity and has been identified more than 500 mutations distributed in 10 genes: KCNQ1, HERG, SCN5A, KCNE1, KCNE2, ANKB, KCNJ2, CACNA1A, CAV3 and SCN4B. Despite advances in the field, 25-30% of patients remain undiagnosed genetic. Genetic testing plays an important role and is particularly useful in cases with nondiagnostic or borderline ECG findings.

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Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a cardiac channelopathy characterized by altered intracellular calcium handling resulting in ventricular arrhythmias and high risk of cardiac sudden death in young cases with normal structural hearts. Patients present with exertional syncope and the trademark dysrhythmia is polymorphic and/or bidirectional ventricular tachycardia during exercise or adrenergic stimulation. Early detection of CPVT is crucial because opportune medical intervention prevents sudden cardiac death. Mutations in the ryanodine receptor RYR2 explain nearly 70% of the CPVT cases and cause the autosomic dominant form of the disease. Mutations in calsequestrin 2 causes a recessive form and explain less than 5% of all cases. Genetic screening in CPVT, besides providing early detection of asymptomatic carriers at risk, has provided important insights in the mechanism underlying the disease. Mutational analysis of RYR2 has been a challenge due to the large size of the gene, 105 exons encoded for 4,967 amino-acids. In this review we analyze general concepts of the disease, differential diagnosis and strategies for genetic screening.

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Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a cardiac channelopathy characterized by altered intracellular calcium handling resulting in ventricular arrhythmias and high risk of cardiac sudden death in young cases with normal structural hearts. Patients present with exertional syncope and the trademark dysrhythmia is polymorphic and/or bidirectional ventricular tachycardia during exercise or adrenergic stimulation. Early detection of CPVT is crucial because opportune medical intervention prevents sudden cardiac death. Mutations in the ryanodine receptor RYR2 explain nearly 70% of the CPVT cases and cause the autosomic dominant form of the disease. Mutations in calsequestrin 2 causes a recessive form and explain less than 5% of all cases. Genetic screening in CPVT, besides providing early detection of asymptomatic carriers at risk, has provided important insights in the mechanism underlying the disease. Mutational analysis of RYR2 has been a challenge due to the large size of the gene, 105 exons encoded for 4,967 amino-acids. In this review we analyze general concepts of the disease, differential diagnosis and strategies for genetic screening.

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The long QT syndrome (LQTS) is a genetic disorder characterized by prolongation of the QT interval in the electrocardiogram (ECG) and a propensity to "torsades de pointes" ventricular tachycardia frequently leading to syncope, cardiac arrest, or sudden death usually in young otherwise healthy individuals. LQTS caused by mutations of predominantly potassium and sodium ion channel genes or channel-interacting proteins leading to positive overcharge of myocardial cell with consequent heterogeneous prolongation of repolarization in various layers and regions of myocardium. These conditions facilitate the early after-depolarization and reentry phenomena underlying development of polymorphic ventricular tachycardia observed in patients with LQTS. Obtaining detailed patient history regarding cardiac events in the patient and his/her family members combined with careful interpretation of standard 12-lead ECG (with precise measurement of QT interval in all available ECGs and evaluation of T-wave morphology) usually is sufficient to diagnose the syndrome. The LQTS show great genetic heterogeneity and has been identified more than 500 mutations distributed in 10 genes: KCNQ1, HERG, SCN5A, KCNE1, KCNE2, ANKB, KCNJ2, CACNA1A, CAV3 and SCN4B. Despite advances in the field, 25-30% of patients remain undiagnosed genetic. Genetic testing plays an important role and is particularly useful in cases with nondiagnostic or borderline ECG findings.

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INTRODUCTION: Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS: The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS: In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION: Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.

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