Cardiac Biomarkers Aid in Differentiation of Kawasaki Disease from Multisystem Inflammatory Syndrome in Children Associated with COVID-19.

Kawasaki disease (KD) and Multisystem Inflammatory Syndrome in Children (MIS-C) associated with COVID-19 show clinical overlap and both lack definitive diagnostic testing, making differentiation challenging. We sought to determine how cardiac biomarkers might differentiate KD from MIS-C. The International Kawasaki Disease Registry enrolled contemporaneous KD and MIS-C pediatric patients from 42 sites from January 2020 through June 2022. The study population included 118 KD patients who met American Heart Association KD criteria and compared them to 946 MIS-C patients who met 2020 Centers for Disease Control and Prevention case definition. All included patients had at least one measurement of amino-terminal prohormone brain natriuretic peptide (NTproBNP) or cardiac troponin I (TnI), and echocardiography. Regression analyses were used to determine associations between cardiac biomarker levels, diagnosis, and cardiac involvement. Higher NTproBNP (≥ 1500 ng/L) and TnI (≥ 20 ng/L) at presentation were associated with MIS-C versus KD with specificity of 77 and 89%, respectively. Higher biomarker levels were associated with shock and intensive care unit admission; higher NTproBNP was associated with longer hospital length of stay. Lower left ventricular ejection fraction, more pronounced for MIS-C, was also associated with higher biomarker levels. Coronary artery involvement was not associated with either biomarker. Higher NTproBNP and TnI levels are suggestive of MIS-C versus KD and may be clinically useful in their differentiation. Consideration might be given to their inclusion in the routine evaluation of both conditions.

Emerging Insights Into the Pathophysiology of Multisystem Inflammatory Syndrome Associated With COVID-19 in Children.

Multisystem inflammatory syndrome in children (MIS-C) has emerged as a rare delayed hyperinflammatory response to SARS-CoV-2 infection and causes severe morbidity in the pediatric age group. Although MIS-C shares many clinical similarities to Kawasaki disease (KD), important differences in epidemiologic, clinical, immunologic, and potentially genetic factors exist and suggest potential differences in pathophysiology and points to be explored and explained. Epidemiologic features include male predominance, peak age of 6 to12 years, and specific racial or ethnicity predilections. MIS-C is characterized by fever, prominent gastrointestinal symptoms, mucocutaneous manifestations, respiratory symptoms, and neurologic complaints, and patients often present with shock. Cardiac complications are frequent and include ventricular dysfunction, valvular regurgitation, pericardial effusion, coronary artery dilation and aneurysms, conduction abnormalities, and arrhythmias. Emerging evidence regarding potential immunologic mechanisms suggest that an exaggerated T-cell response to a superantigen on the SARS-CoV-2 spike glycoprotein-as well as the formation of autoantibodies against cardiovascular, gastrointestinal, and endothelial antigens-are major contributors to the inflammatory milieu of MIS-C. Further studies are needed to determine both shared and distinct immunologic pathway(s) that underlie the pathogenesis of MIS-C vs both acute SARS-CoV-2 infection and KD. There is evidence to suggest that the rare risk of more benign mRNA vaccine-associated myopericarditis is outweighed by a reduced risk of more severe MIS-C. In the current review, we synthesize the published literature to describe associated factors and potential mechanisms regarding an increased risk of MIS-C and cardiac complications, provide insights into the underlying immunologic pathophysiology, and define similarities and differences with KD.

Use of Infliximab in the Treatment of Macrophage Activation Syndrome Complicating Kawasaki Disease.

Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology. KD can be complicated with macrophage activation syndrome. The optimal treatment for this KD complication has not been established, and a variety of treatments have been used. Infliximab, a chimeric monoclonal antibody that binds tumor necrosis factor, has proved to be efficacious in IV gammaglobulin resistant KD. We present 2 cases of KD complicated with macrophage activation syndrome, including 1 patient with DiGeorge syndrome successfully treated with a combined treatment of IV gammaglobulin, corticosteroids, cyclosporine, and infliximab.

Kawasaki disease mimickers.

BACKGROUND: Kawasaki disease (KD) is an acute systemic vasculitis that predominantly affects patients younger than 5 years. In the absence of an available, affordable diagnostic test, detailed clinical history and physical examination are still fundamental to make a diagnosis. METHODS: We present five representative cases with KD-like presentations: systemic onset juvenile idiopathic arthritis, mycoplasma-induced rash and mucositis, staphylococcal scalded skin syndrome, BCGosis, and the recently described multisystemic inflammatory syndrome in children (MIS-C) associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) virus. RESULTS: Rash, fever, and laboratory markers of inflammation can be present in several childhood diseases that may mimic KD. CONCLUSION: The term 'Kawasaki syndrome' instead of 'Kawasaki disease' may be more appropriate. Physicians should consider an alternative diagnosis that may mimic KD, particularly considering MIS-C during the present pandemic, as an aggressive diagnostic and therapeutic approach is needed.

Enfermedad de Kawasaki en lactantes bajo un año de edad: un reto para el diagnóstico y tratamiento de los pacientes. Experiencia en un centro hospitalario en México / Kawasaki disease in infants under one year of age: a challenge for the diagnosis and treatment of patients. Experience in a hospital center in Mexico

Resumen Antecedentes: La enfermedad de Kawasaki (EK) en lactantes bajo un año de edad es poco frecuente en la mayoría de los países. Este grupo de pacientes tienen mayor riesgo de desarrollar complicaciones cardiacas. Objetivo: Evaluar el comportamiento clínico, tratamiento empleado y pronóstico cardiaco en lactantes bajo un año de edad atendidos por EK en un hospital pediátrico de tercer nivel en la Ciudad de México. Pacientes y Métodos: Estudio retrospectivo, descriptivo, de pacientes con diagnóstico de EK desde agosto de 1995 a agosto de 2019. Se estudió la presentación clínica, los exámenes de laboratorio, el tratamiento administrado y el desarrollo de lesiones coronarias en pacientes bajo un año de edad y se comparó con pacientes mayores. Resultados: Se estudiaron 687 pacientes, 152 de ellos eran lactantes bajo un año de edad (22,1%). Hubo un mayor tiempo al diagnóstico de la EK en los lactantes menores, con un incremento de presentaciones clínicas incompletas; este grupo de pacientes desarrolló en forma más frecuente lesiones coronarias en comparación con los pacientes mayores y también tuvo un mayor porcentaje de aneurismas coronarios gigantes. Hubo dos fallecimientos en los lactantes menores, secundarios a infarto al miocardio. Conclusiones: El diagnóstico de EK en pacientes bajo un año de edad es un reto diagnóstico con presentaciones clínicas incompletas y mayor riesgo de desarrollar complicaciones cardiacas graves.

Abstract Background: Frequency of Kawasaki disease (KD) in infants is low in almost all countries. These patients are at higher risk of developing cardiac complications. Aim: To evaluate the clinical features, treatment used and cardiac outcome in infants under one year of age attending for KD in a third level pediatric hospital in Mexico City, Mexico. Methods: A cross-sectional study was conducted in our hospital from August 1995 to August 2019. We analyzed the clinical features, laboratory results, treatment used and cardiac outcomes in infants younger than one year of age and compared them with older patients. Results: We included 687 patients, 152 were younger than one year of age (22.1%). There was a delayed diagnosis in younger patients with an increased frequency of incomplete clinical presentations. Coronary artery abnormalities were most common in younger infants who also had an increased frequency of giant coronary artery aneurysms. Two patients in the younger group died in the acute phase of KD of myocardial infarction. Conclusions: Diagnosis of KD in infants younger than 1 year of age is a clinical challenge with an increased rate of incomplete clinical presentations and also an increased risk of development of severe cardiac complications.

Kawasaki Disease in Infants in the First 3 Months of Age in a Mexican Population: A Cautionary Tale.

Background: Kawasaki disease (KD) is an acute febrile illness that largely affects young children before 5 years of age. Younger children with KD are reported to have a higher prevalence of coronary artery abnormalities. Little is known about infants in the first 3 months of age diagnosed with KD. Methods: A retrospective study was conducted at the National Institute of Pediatrics in Mexico City from 1995 to 2019. Clinical features, laboratory results and cardiac outcomes were recorded. Infants in the first 3 months of age were compared with older patients. Wilcoxon-Mann-Whitney analysis was performed for continuous variables and Fisher's exact test for categorical variables. Results: Six hundred and eighty-eight cases of KD were included in this study. Fourteen cases were diagnosed in the first three months of age. Heart failure and KD shock-syndrome was found in five cases (35.7%). Giant coronary artery aneurysms were found in six cases in the younger group (42.9%). Conclusions: Diagnosis of KD in children younger than 3 months of age is rare. In most cases, an incomplete presentation contributed to a delay diagnosis, treatment, and complications. Younger patients with KD have an increased risk of presenting cardiac complications, including giant coronary artery aneurysms, shock, and death.

[Kawasaki disease in infants under one year of age. A challenge for the diagnosis and treatment of patients. Experience in a hospital center in Mexico]. / Enfermedad de Kawasaki en lactantes bajo un año de edad. Un reto para el diagnóstico y tratamiento de los pacientes. Experiencia en un centro hospitalario en México.

BACKGROUND: Frequency of Kawasaki disease (KD) in infants is low in almost all countries. These patients are at higher risk of developing cardiac complications. AIM: To evaluate the clinical features, treatment used and cardiac outcome in infants under one year of age attending for KD in a third level pediatric hospital in Mexico City, Mexico. METHODS: A cross-sectional study was conducted in our hospital from August 1995 to August 2019. We analyzed the clinical features, laboratory results, treatment used and cardiac outcomes in infants younger than one year of age and compared them with older patients. RESULTS: We included 687 patients, 152 were younger than one year of age (22.1%). There was a delayed diagnosis in younger patients with an increased frequency of incomplete clinical presentations. Coronary artery abnormalities were most common in younger infants who also had an increased frequency of giant coronary artery aneurysms. Two patients in the younger group died in the acute phase of KD of myocardial infarction. CONCLUSIONS: Diagnosis of KD in infants younger than 1 year of age is a clinical challenge with an increased rate of incomplete clinical presentations and also an increased risk of development of severe cardiac complications.

[Cardiac manifestations in the acute phase of Kawasaki disease in a third level children's hospital in Mexico City]. / Manifestaciones cardiacas en la etapa aguda de la enfermedad de Kawasaki en un hospital pediátrico de tercer nivel en la Ciudad de México.

OBJECTIVES: To describe the cardiac manifestations in the acute phase of patients with Kawasaki disease treated in a third level Children's hospital in Mexico City, Mexico. METHODS: A cross-sectional study was conducted in patients with a diagnosis of Kawasaki disease treated in this hospital from August 1995 to December 2016. Information included patient demographics, clinical features, treatment used, electrocardiographic findings, extra-coronary echocardiographic findings, and the development of coronary artery aneurysms in the acute phase of the disease. RESULTS: The study included 508 cases of Kawasaki disease, with a mean age at diagnosis of 37.64±35.56 months (range from 2 to 200 months). Almost two-thirds (65.4%) of the patients were male, with a male/female ratio of 1.88:1. Complete Kawasaki disease was diagnosed in 79.2% of cases. Almost all cases (92.4%) received intravenous immunoglobulin. Twenty-eight patients (5.5%) developed arrhythmias, ST changes developed in 29 patients (5.6%), and 5 patients presented with ischaemic changes. In the initial echocardiographic evaluation, 51 patients (9.9%) were diagnosed with myocarditis, 72 patients (14.0%) with pericarditis and 77 cases (15.0%) developed pericardial effusion. Coronary artery anomalies were detected in 169 cases (32.9%). 32 cases were diagnosed as giant coronary aneurysms. Four patients died from cardiac complications in the acute phase of the disease. CONCLUSIONS: There has been an increase in the diagnosis of Kawasaki disease in Mexico. They presented with more cardiac complications than reported in literature. An increased knowledge of Kawasaki disease is required in Mexico in order to establish the cardiac outcomes of this group of patients.

[QTc interval in the neonatal period in a Mexican population. A pilot study]. / Situación del intervalo QTc en el período neonatal en un hospital del occidente de México, estudio piloto.

INTRODUCTION: QT interval prolongation is associated with ventricular arrhythmias and sudden death syndrome. OBJECTIVE: To determine the value of QTc interval in healthy newborns in a general hospital in Jalisco, Mexico, and their outcome during their first months of life. METHODS: The study included healthy newborns from March to November 2016, in the Hospital General of Occidente in Jalisco, Mexico. A 12-lead electrocardiogram was performed at a speed of 25mm/s during the first 48h of life. The QT interval was measured in lead DII, and the QTc interval was calculated using the Bazett formula. Patients detected with QTc prolongation were assessed monthly with an ECG and echocardiogram. If they persisted with prolonged QTc interval, they were re-evaluated at 6 months with an ECG, 24h Holter, and electrocardiography study on parents and siblings. Those who persisted with prolonged QTc interval were evaluated with an ECG at 9 months. RESULTS: The study included 548 patients. The mean QTc interval at birth was 459 ms; during this period 33 patients has a QTc greated that 470 ms; which were evaluated monthly with a new electrocardiographic study, obtaining a mean QTc interal of 446 ms. At 6 months 16 patients were evaluated, with a mean QTc interval of 434ms. At 9 months, 6 patients were found to have a mean QTc interval of 438ms, and only 4 patients persisted with a prolonged QTc interval. CONCLUSIONS: The QTc interval in our population is prolonged compared to other populations and with a gradual return to normal.

Situación del intervalo QTc en el período neonatal en un hospital del occidente de México, estudio piloto / QTc interval in the neonatal period in a Mexican population. A pilot study

Resumen Introducción: La prolongación del intervalo QT se asocia con arritmias ventriculares y muerte súbita. Objetivo: Determinar el valor del intervalo QTc en recién nacidos sanos y evaluar su comportamiento durante los primeros meses de vida. Métodos: Recién nacidos sanos a término de marzo-noviembre 2016 en el Hospital General de Occidente del Estado de Jalisco, México. Se les practicó un electrocardiograma de 12 derivaciones a una velocidad de 25 mm/s durante las primeras 48 h. Se midió el intervalo QT en DII y se calculó el QTc mediante la fórmula de Bazett. Los pacientes a los que se detectó prolongación del QTc en sus primeras 48 h se valoraron al mes con ECG y ecocardiograma. Si persistieron con QTc alargado se revaloraron a los 6 meses con ECG, Holter de 24 h y estudio electrocardiográfico a padres y hermanos. Los que persistieron con QTc alargado se revaloraron a los 9 meses con ECG. Resultados: Se incluyeron 548 pacientes. La media del intervalo QTc al nacimiento fue de 459 ms; durante este período 33 pacientes presentaron un QTc mayor de 470 ms, los cuales fueron evaluados al mes mediante un nuevo estudio electrocardiográfico, obteniendo una media del intervalo QTc de 446 ms. A los 6 meses se evaluaron 16 pacientes, con una media del intervalo QTc de 434 ms. A los 9 meses se evaluaron 6 pacientes, con una media del intervalo QTc de 438 ms, y solo 4 pacientes persistieron con QTc prolongado. Conclusiones: El intervalo QTc en nuestros pacientes es más prolongado en comparación con otras poblaciones y muestra una normalización paulatina.

Abstract Introduction: QT interval prolongation is associated with ventricular arrhythmias and sudden death syndrome. Objective: To determine the value of QTc interval in healthy newborns in a general hospital in Jalisco, Mexico, and their outcome during their first months of life. Methods: The study included healthy newborns from March to November 2016, in the Hospital General of Occidente in Jalisco, Mexico. A 12-lead electrocardiogram was performed at a speed of 25 mm/s during the first 48 h of life. The QT interval was measured in lead DII, and the QTc interval was calculated using the Bazett formula. Patients detected with QTc prolongation were assessed monthly with an ECG and echocardiogram. If they persisted with prolonged QTc interval, they were re-evaluated at 6 months with an ECG, 24 h Holter, and electrocardiography study on parents and siblings. Those who persisted with prolonged QTc interval were evaluated with an ECG at 9 months. Results: The study included 548 patients. The mean QTc interval at birth was 459 ms; during this period 33 patients has a QTc greated that 470 ms; which were evaluated monthly with a new electrocardiographic study, obtaining a mean QTc interal of 446 ms. At 6 months 16 patients were evaluated, with a mean QTc interval of 434 ms. At 9 months, 6 patients were found to have a mean QTc interval of 438 ms, and only 4 patients persisted with a prolonged QTc interval. Conclusions: The QTc interval in our population is prolonged compared to other populations and with a gradual return to normal.

Manifestaciones cardiacas en la etapa aguda de la enfermedad de Kawasaki en un hospital pediátrico de tercer nivel en la Ciudad de México / Cardiac manifestations in the acute phase of Kawasaki disease in a third level children's hospital in Mexico City

Resumen Objetivo: Describir las manifestaciones cardiacas en la etapa aguda de la enfermedad de Kawasaki en pacientes atendidos en un hospital de tercer nivel de la Ciudad de México, México. Métodos: Estudio retrospectivo, descriptivo en pacientes con diagnóstico de enfermedad de Kawasaki de agosto de 1995 a diciembre del 2016 en el Instituto Nacional de Pediatría, México. Se estudio la demografía de los pacientes, características clínicas, tratamiento empleado y desarrollo de complicaciones cardiacas en la etapa aguda de la enfermedad. Resultados: Se estudiaron 508 casos de enfermedad de Kawasaki. La edad media al diagnóstico fue de 37.64 ± 35.56 meses. Predominio de pacientes masculinos del 65.4%, con una relación masculino/femenino de 1.88:1. La mayoría de los casos (79.2%) tuvo una presentación completa. La gammaglobulina intravenosa fue administrada en 92.4% de los casos. Veintiocho pacientes (5.5%) desarrollaron arritmias, se presentaron cambios en el segmento ST en 29 pacientes (5.6%) y 5 pacientes desarrollaron isquemia miocárdica. En el ecocardiograma inicial, 51 pacientes (9.9%) presentaron datos de miocarditis, 72 pacien- tes (14%) datos de pericarditis y 77 casos tuvieron derrame pericárdico (15%). Se detectaron alteraciones en las arterias coronarias en 169 casos (32.9%). Cuatro pacientes fallecieron en la etapa aguda de la enfermedad por complicaciones cardiacas de la enfermedad de Kawasaki. Conclusiones: En México cada vez existen más casos de enfermedad de Kawasaki con un alto porcentaje de manifestaciones cardiacas al diagnóstico. Se requiere de un mayor conocimiento de la enfermedad en México, para poder establecer cuál es la evolución cardiológica de los pacientes en el país.

Abstract Objectives: To describe the cardiac manifestations in the acute phase of patients with Kawasaki disease treated in a third level Children's hospital in Mexico City, Mexico. Methods: A cross-sectional study was conducted in patients with a diagnosis of Kawasaki disease treated in this hospital from August 1995 to December 2016. Information included patient demographics, clinical features, treatment used, electrocardiographic findings, extra-coronary echocardiographic findings, and the development of coronary artery aneurysms in the acute phase of the disease. Results: The study included 508 cases of Kawasaki disease, with a mean age at diagnosis of 37.64 ± 35.56 months (range from 2 to 200 months). Almost two-thirds (65.4%) of the patients were male, with a male/female ratio of 1.88:1. Complete Kawasaki disease was diagnosed in 79.2% of cases. Almost all cases (92.4%) received intravenous immunoglobulin. Twenty-eight patients (5.5%) developed arrhythmias, ST changes developed in 29 patients (5.6%), and 5 patients presented with ischaemic changes. In the initial echocardiographic evaluation, 51 patients (9.9%) were diagnosed with myocar- ditis, 72 patients (14.0%) with pericarditis and 77 cases (15.0%) developed pericardial effusion. Coronary artery anomalies were detected in 169 cases (32.9%). 32 cases were diagnosed as giant coronary aneurysms. Four patients died from cardiac complications in the acute phase of the disease. Conclusions: There has been an increase in the diagnosis of Kawasaki disease in Mexico. They presented with more cardiac complications than reported in literature. An increased knowledge of Kawasaki disease is required in Mexico in order to establish the cardiac outcomes of this group of patients.

Reaction of the BCG Scar in the Acute Phase of Kawasaki Disease in Mexican Children.

BACKGROUND: Kawasaki disease (KD) is an acute self-limited systemic vasculitis that primarily affects children <5 years old. There is no specific diagnostic test. A reaction at the Bacille Calmette-Guérin (BCG) inoculation site has been reported as a common finding in patients with KD where BCG vaccination is mandatory. The purpose of this study was to evaluate the frequency of reactivation of the BCG in Mexican children diagnosed with KD. METHODS: A retrospective study of all patients diagnosed with KD from August 1, 1995, to August 31, 2015, at our Institution was performed. The clinical profile, laboratory results, treatment used and coronary artery abnormalities in the BCG reactive and the BCG nonreactive groups were analyzed and compared. RESULTS: We included 399 patients with KD. Ninety-seven (24.3%) had BCG reaction at the inoculation site. The BCG(+) group was younger than the BCG(-) group (P < 0.000). There were 18 (18.55%) incomplete cases in the BCG(+) group compared with 65 (21.52%) in the BCG(-) group without statistical significance. The BCG+ group developed coronary artery aneurysms in 37 cases and the BCG(-) group developed coronary artery aneurysms in 111 cases without statistical significance. Multivariate analysis showed that younger age at diagnosis was the only variable associated with a reaction at the BCG inoculation site in patients with KD. CONCLUSIONS: In Mexico, a country with a National BCG Vaccination Program and a low incidence of KD, reaction at the BCG inoculation site could be a useful diagnostic sign of KD.

Screening of late-onset Pompe disease in a sample of Mexican patients with myopathies of unknown etiology: identification of a novel mutation in the acid alpha-glucosidase gene.

Pompe disease or glycogen-storage disease type 2 (GSD2, OMIM 232300) is an autosomal recessive disorder caused by mutations in the acid alpha-glucosidase gene. Late-onset GSD2 resembles some limb-girdle and Becker muscular dystrophies. The screening of GSD2 through the measurement of acid alpha-glucosidase activity in dried blood spots was applied to a selected sample of 5 Mexican patients with proximal myopathies of unknown etiology. Only 1 male patient showed a low level of acid alpha-glucosidase activity and a compound heterozygote genotype for the c.-32-13T>G splicing mutation present in most white late-onset Pompe disease cases and the novel mutation p.C558S. To our knowledge, this is the first report of a Mexican patient with late-onset GSD2. The identification of c.-32-13T>G in our patient could reflect the genetic contribution of European ancestry to the Mexican population. The enzymatic screening of GSD2 could be justified in patients with myopathies of unknown etiology.

[Kawasaki's disease: must fever be obligatory criteria?]. / Enfermedad de Kawasaki. La fiebre debe ser un criterio obligatorio?

Kawasaki disease (KD) is one of the most common vasculitic disorders in children. The diagnosis is made based on the presence of clinical criteria. We present an exceptional case that fulfilled the clinical criteria of KD except the presence of fever. We consider that the criteria should be revised, with fever not to be considered as an obligate criterion. The similarities of KD with recurrent toxin-mediated perineal erythema are discussed, the latter being a possible attenuated form of KD.

Ablación con radiofrecuencia en el tratamiento de las arritmias supraventriculares en pediatría. Experiencia en 203 pacientes consecytivos / Radiofrequency ablation in the treatment of supraventricular arbhythmias in pediatric patients. Experience with 203 consecutive patients

Informamos los resultados de la ablación con radiofrecuencia en 203 pacientes menores de 18 años con taquiarritmias supraventriculares tratadas en el Departamento de Electrofisiología del Instituto Nacional de Cardiología "Ignacio Chávez" entre abril de 1992 y junio de 1997. La taquicardia fue causada por una vía accesoria en 181 pacientes (89.1 por ciento) con un total de 187 vías accesorias, por reentrada intranodal en 18 casos (8.8 por ciento) y flutter atrial en 4 pacientes (1.9 por ciento). El procedimiento tuvo éxito en los pacientes con vías accesorias en 171 casos (91.4 por ciento), 23 pacientes tuvieron recurrencias (12.2 por ciento). La ablación de la reentrada intranodal tuvo éxito en 18 casos: con ablación selectiva de la vía lenta en 17 y de la vía rápida en un paciente; en 3 pacientes recurrió la arritmia (16.6 por ciento. En los casos de flutter atrial, la ablación tuvo éxito en los 4 pacientes en quienes se realizó con una sola recurrencia (25 por ciento). En el total de la serie, la ablación fue exitosa en 193 casos (95 por ciento) con recurrencias en 27 casos (13.3 por ciento). Hubo complicaciones sólo en 5 pacientes (2.4 por ciento). Se concluye que la ablación de vías accesorias con radiofrecuencia es un procedimiento eficaz y seguro para suprimir las arritmias supraventriculares en niños