Utilidad de la midodrina para controlar el síncope vasovagal: ¿la recomienda la evidencia? / Usefulness of Midodrine for the Control of Recurrent Vasovagal Syncope: Does the Evidence Recommend it? / Utilidade da midodrina no controle da síncope vasovagal: as evidencias a recomendam?

Introducción:El síncope vasovagal es la principal causa de pérdida transitoria de la conciencia, y es un motivo de consulta cada vez más frecuente en pediatría y medicina del adulto. La midodrina es un agonista de los recepto-res alfa, de acción periférica, empleada principalmente en el manejo de la hipotensión ortostática; sin embargo, también se ha evaluado en el síncope vasovagal, con resultados prometedores.Objetivo:Analizar la evidencia más reciente sobre la utilidad de la midodrina para el control y la prevención del síncope vasovagal.Materiales y métodos: Se realizó una búsqueda bibliográfica utilizando términos de búsqueda como Vasovagal Syncope y Midodrine, así como sinónimos, que se combinaron con operadores booleanos, en cinco bases de datos, hasta octubre del 2022. Se incluyeron estudios originales, revisiones sistemáticas y metanálisis, publicados tanto en inglés como en español.Resultados:Ensayos controlados aleatorizados y revisiones sistemáticas y metanálisis difieren ligeramente entre resultados, pero estos demuestran un efecto global protector. La evidencia más reciente y completa indica que utilizar este agente reduce significativamente la positividad al realizar la prueba de la mesa inclinada y que previene la aparición de episodios sincopales.Conclusiones:Aunque la evidencia actual sobre la eficacia de la midodrina respecto a la prevención y control del síncope vasovagal es limitada, se observa un efecto protector significativo, porque disminuye el riesgo de sufrir un episodio sincopal, aproximadamente hasta en un 50 %.Palabras clave: midodrina; síncope vasovagal; síncope; adrenérgicos; medicina basada en la evidencia

Introduction: Vasovagal syncope is the main cause of transient loss of consciousness, being an in-creasingly frequent reason for consultation in pediatrics and adult medicine. Midodrine, a periphe-rally acting alpha-receptor agonist, is mainly used in the management of orthostatic hypotension. However, it has also been evaluated in vasovagal syncope, with promising results. Objective: To analyze the most recent evidence on the usefulness of midodrine for the control and prevention of vasovagal syncope. Materials and Methods: A literature search was performed using search terms such as "Vasovagal Syncope" and "Midodrine," as well as synonyms, which were combined with Boolean operators, in 5 databases until October 2022. Original studies, systematic reviews and meta-analyses, published in both English and Spanish, were included. Results: Randomized controlled trials and systematic reviews and meta-analyses differ slightly between results, but these demonstrate an overall protective effect. The most recent and complete evidence shows that using this agent significantly reduces the probability of positivity when performing the tilt table test and prevents the occurrence of syncopal episodes. Conclusions: Although current evidence on the efficacy of midodrine with respect to the prevention and control of vasovagal syncope is limited, a significant protective effect is observed, reducing the risk of suffering syncopal episode by approximately up to 50%

Introdução: a síncope vasovagal é a principal causa de perda transitória de consciência e é um motivo cada vez mais comum de consulta em pediatria e medicina de adultos. A midodrina é um agonista do receptor alfa de ação periférica usado principalmente no tratamento da hipotensão ortostática; no entanto, ela também foi avaliada na síncope vasovagal, com resultados promissores. Objetivo: Revisar as evidências mais recentes sobre a utilidade da midodrina para o controle e a pre-venção da síncope vasovagal. Materiais e métodos: Foi realizada uma pesquisa na literatura usando termos de pesquisa como Va-sovagal, Syncope e Medodrine, bem como sinônimos, que foram combinados com operadores boo-leanos, em cinco bancos de dados, até outubro de 2022. Foram incluídos estudos originais, revisões sistemáticas e metanálises, publicados em inglês e espanhol. Resultados: Os ensaios clínicos randomizados, as revisões sistemáticas e as metanálises diferem ligei-ramente entre os resultados, mas demonstram um efeito protetor geral. As evidências mais recentes e abrangentes indicam que o uso desse agente reduz significativamente a positividade no teste de inclinação da mesa e evita a ocorrência de episódios de síncope. Conclusões: Embora as evidências atuais sobre a eficácia da midodrina em relação à prevenção e ao controle da síncope vasovagal sejam limitadas, observa-se um efeito protetor significativo, pois ela diminui o risco de sofrer um episódio sincopal em aproximadamente 50%

Reflex cardioinhibitory syncope potentially related to SARS-CoV-2 infection: a case report / Síncope cardioinibitória reflexa potencialmente relacionada à infecção por SARS-CoV-2: um relato de caso

Autonomic dysfunction related to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is increasingly described in the literature. We report the case of a 30-year-old male with a background of asthma and migraine who experienced a second episode of SARS-CoV-2 infection characterized by mild respiratory symptoms. Twenty-four days after the symptom onset, he developed acute syncope. A tilt test revealed a neuromediated cardioinhibitory response with asystole (Vasovagal Syncope International Study ­ VASIS type 2B). The temporal association between SARS-CoV-2 infection and syncope seems to indicate a probable causal relationship, which requires corroboration by future studies.

Disfunção autonômica relacionada à infecção por coronavírus-2 da síndrome respiratória aguda grave (SARS-CoV-2) vem sendo cada vez mais descrita na literatura. Relatamos o caso de um homem de 30 anos de idade, com histórico de asma e enxaqueca, que apresentou um segundo episódio de infecção por SARS-CoV-2 caracterizado por sintomas respiratórios leves. Vinte e quatro dias após o início dos sintomas, desenvolveu um quadro agudo de síncope. Um teste de inclinação revelou uma resposta cardioinibitória neuromediada com assistolia (Vasovagal Syncope International Study ­ VASIS tipo 2B). A associação temporal entre infecção por SARS-CoV-2 e síncope parece indicar uma provável relação causal, a qual requer corroboração por estudos futuros.

Crisis hipertensiva y bradicardia secundaria a intoxicación por midodrina / Hypertensive crisis and bradycardia secondary to midodrine intoxication

Resumen El síncope, definido como una pérdida transitoria de la conciencia que cursa con recuperación espontánea y completa, es secundario a un amplio grupo etiológico, incluido el de origen vasovagal desencadenado por una descarga adrenérgica u ortostatismo. El tratamiento de esta entidad incluye medidas no farmacológicas y farmacológicas, como la administración de midodrina, un agonista de los receptores a de acción periférica, usada en el control de la hipotensión ortostática y cuyo empleo ha demostrado mejoría en los síntomas de esta alteración. Se presenta el caso de una mujer de 18 años, con antecedente de síncope vasovagal en tratamiento con medidas no farmacológicas y midodrina desde seis meses antes, quien consultó al servicio de urgencias de un centro de atención de nivel IV por cuadro clínico consistente en ingestión intencionada de una sobredosis de midodrina. En el ingreso se documentaron crisis hipertensiva, bradicardia extrema y compromiso hepático y renal. Se indicó tratamiento sintomático con resolución de las alteraciones clínicas y paraclínicas e intervención del equipo de salud mental.

Abstract Syncope, defined as a transitory loss of consciousness characterised by its rapid onset, short duration, and spontaneous complete recovery, is secondary to a wide ethiological group, such as the vasovagal origin triggered by an adrenergic discharge or orthostatism. The management of this entity includes both non-pharmacological measures and pharmacological treatment such as the use of midodrine, a peripherally acting alpha receptor agonist, used in the management of orthostatic hypotension, whose use has shown improvement in the symptoms of this condition. We present a clinical case of an 18-year-old woman, with a history of vasovagal syncope under treatment with midodrine and non-pharmacological measures for 6 months, who was admitted to the emergency department of a level IV care center due to an intentional intake of midodrine overdose. Upon admission, a hypertensive crisis with extreme bradycardia, and liver and kidney involvement were documented. Symptom´s management was started with resolution of clinical and paraclinical alterations, and intervention by the mental health team.

Etiology and Age Distribution of Syncope in Delta Area Patients

Background: Syncope is a Total Loss of Consciousness (TLOC) due to cerebral hypo-perfusion, characterized by a rapid onset, short duration, and spontaneous complete recovery. It shares many clinical features with other disorders; it therefore presents in many differential diagnoses. This group of disorders is labelled TLOC. The aim of the present study was to determine the etiologies and the age distribution of patients with syncope in Delta area. Methods: This study included thirty patients who had at least one episode of syncope. All patients in this study were subjected to history taking, clinical examination, laboratory investigations, standard 12-lead Electrocardiogram (ECG), Resting Transthoracic Echocardiography (TTE). Some patients were subjected to Prolonged ECG monitoring (Holter, Event, ILR), Brain computed tomography (CT) and Magnetic resonance imaging (MRI), Tilt table test and Electrophysiology study (EP study). Results: Most common ECG rhythm was normal sinus rhythm, complete heart block, left ventricular hypertrophy, Slow Atrial fibrillation (AF), Left bundle branch block (LBBB), ventricular tachycardia. The most common diagnosis of syncope was vasovagal syncope, idiopathic syncope then cardiac syncope. Incidence of idiopathic syncope in populations under 40 years was significantly higher than in populations over 40 years, meanwhile regarding cardiac-related etiology for syncope in patients under age 40 was significantly lower than those patients over age 40. Conclusion: For age distribution, the incidence of idiopathic syncope in populations under 40 years was significantly higher than in populations over 40 years, meanwhile cardiac-related etiology for syncope in patients under age 40 was significantly lower than those patients over age 40.

Differential diagnosis of vasovagal syncope in children / 国际儿科学杂志

Vasovagal syncope(VVS) is a common clinical reflex syncope, which is easy to occur repeatedly.Although there is no direct life risk, it causes varying degrees of physical injury and psychological disorders to children, affects their daily life and study, and also causes anxiety of parents.At present, the diagnosis of VVS mainly depends on the vertical tilt table test.With the development of translational medicine, identifying VVS and other types of syncope by other methods has achieved important clinical value, which will be more convenient for primary hospital to carry out the related work of syncope diagnosis and treatment.This paper will review the related progress in the differential diagnosis of VVS.

Correlation of plasma prolactin and cortisol with vasovagal syncope in children / 中华实用儿科临床杂志

Objective:To investigate the changes of plasma prolactin (PRL) and cortisol (Cor) in the head up tilt test (HUT) in children with vasovagal syncope (VVS), and their correlation with VVS.Methods:From May 2019 to May 2020, 75 children diagnosed as VVS through positive HUT in the Children′s Hospital, Capital Institute of Pediatrics were retrospectively recruited as VVS group, while 29 healthy children with negative HUT during the same period were collected in healthy control group.Heart rate (HR) and blood pressure [systolic and diastolic blood pressure (SBP, DBP)] were monitored using a noninvasive continuous blood pressure monitor.The changes of HR, SBP and DBP were analyzed and their differences between the supine position and positive reaction of HUT were compared.The contents of PRL and Cor in the supine position and positive reaction of HUT were measured using the electrochemiluminescence, and their changes (ΔPRL and ΔCor) were calculated.Differences between groups were analyzed by the two-tailed Student′s t-test or the Mann- Whitney test.Receiver operating characteristic (ROC) curves were plotted to analyze the predictive value of ΔPRL on VVS. Results:There were no significant differences in the age, gender, body mass index, blood electrolyte, syncope frequency and syncope course between VVS group and healthy control group (all P>0.05). There was no significant difference in syncope frequency and course of syncope among subtypes of VVS group (vasodepressor syncope, mixed syncope, cardioinhibitory syncope)(all P>0.05). Compared with healthy control group, PRL after HUT was significantly higher in VVS group[36.23 (22.08, 61.97) μg/L vs.11.47 (8.00, 23.25 ) μg/L, Z=-5.40, P<0.01]. Both ΔPRL [25.36( 9.92, 48.93) μg/L vs.-0.10(- 2.67, 9.32) μg/L, Z=-5.39, P<0.01] and ΔCor [(84.4±43.6) μg/L vs.(57.6±64.6) μg/L, t=-2.44, P<0.05 ] were significantly higher in VVS group than those of healthy control group.PRL at HUT positive reaction was negatively correlated with SBP and DBP ( r=- 0.46, -0.45, all P<0.01). In VVS group, PRL at HUT positive reaction was negatively correlated with SBP ( r=-0.38, -0.24, all P<0.05). In VVS group, ΔCor after HUT was negatively correlated with SBP ( r=-0.25, P<0.05). ROC curves revealed that the cut-off value of ΔPRL in predicting HUT was 4.03 μg/L, with the sensitivity of 89.3% and specificity of 72.4%. Conclusions:Plasma PRL and Cor increase during syncope in VVS children, and plasma PRL is correlated with blood pressure drop.The increased plasma level of PRL in VVS children with positive HUT is correlated with blood pressure, and ΔCor is correlated with SBP.Plasma PRL and Cor may be involved in the pathogenesis of VVS and ΔPRL presents the diagnostic potential of VVS in children.

Evaluación de la frecuencia cardiaca durante la bipedestación activa inicial en pacientes que padecen síncope vasovagal / Evaluation of the heart rate during initial active standing in patients with vasovagal syncope

Introducción: El síncope vasovagal es la causa más frecuente de pérdida breve de la conciencia, en su etiopatogenia se reporta una disfunción autonómica que puede ponerse de manifiesto en la bipedestación activa inmediata. Objetivo: Comparar la dinámica de los cambios de la frecuencia cardíaca durante la bipedestación activa inmediata, de pacientes que padecen síncope vasovagal y sujetos controles. Métodos: Se evaluaron 132 sujetos supuestamente sanos (grupo A) entre 18 y 25 años y 156 pacientes con síncopes vasovagales; fueron divididos por su respuesta ante la bipedestación prolongada, negativa 111 (grupo B) y positiva 45 (grupo C). Se registró la actividad electrocardiográfica en decúbito supino y al inicio de la bipedestación activa, se obtuvo las secuencias de intervalos RR. Se comparó la frecuencia cardíaca en los 3 grupos, con 22 indicadores (posicionales, temporales, ordinales y relacionales, promedio y de la velocidad de los cambios). Resultados: No hubo diferencias en los indicadores promedio, sin embargo, algunos que evalúan la velocidad del cambio inicial, fueron significativamente menores en el grupo A comparado con B y C (p < 0,05), mientras que los que evalúan la velocidad de recuperación, fueron significativamente menores en el grupo C comparado con A y B. Conclusión: La dinámica de los cambios de frecuencia, permitió encontrar indicadores que pueden considerarse posibles predictores de una respuesta cardiovascular inadecuada en pacientes con síncope vasovagal(AU)

Introduction: Vasovagal syncope is the most frequent cause of brief loss of consciousness, in its etiopathogenesis an autonomic dysfunction is reported that can be manifested in immediate active standing. Objective: To compare the dynamics of heart rate changes during immediate active standing of patients suffering from vasovagal syncope with control subjects. Methods: 132 supposedly healthy subjects (group A) between 18 and 25 years old and 156 patients with vasovagal syncope were evaluated, which were divided by their response to prolonged standing, negative 111 (group B) and positive 45 (group C). Electrocardiographic activity was recorded in the supine position and at the beginning of active standing, the sequences of RR intervals were obtained. The heart rate was compared in the 3 groups, using 22 indicators (positional, temporal, ordinal and relational, average and of the speed of changes). Results: Differences were not found in the average indicators in the analyzed period, however, some that evaluate the speed of the initial change were significantly lower in group A compared to B and C (p < 0.05), while others that evaluate the speed recovery rates were significantly lower in group C compared to A and B. This allows to characterize, compare and differentiate the groups studied during the complex and rapid interactions that occur in the change of position. Conclusion: The dynamic of frequency changes, allowed to find indicators, which can be considered as possible predictors of an inadequate cardiovascular response in patients with vasovagal syncope(AU)

Detección de síncope vasovagal con adaptación de la Escala de Calgary en estudiantes universitarios colombianos / Using a Calgary Scale adaptation to detect vasovagal syncope in Colombian university students

Resumen Introducción: El síncope vasovagal tiene una incidencia entre 10% y 19% en la población general, el primer episodio suele aparecer en la juventud. Objetivo: Estimar la prevalencia de síncope vasovagal en una población universitaria del sur de Colombia, utilizando una adaptación de la Escala de Calgary como cuestionario diagnóstico. Materiales y métodos: Después de la firma voluntaria del consentimiento informado, los estudiantes fueron entrevistados y se les aplicó la Escala de Calgary. Posteriormente, se realizó un cuestionario de seguimiento a los participantes positivos. Resultados: Participaron 280 estudiantes, el 17% obtuvo un puntaje positivo para síncope vasovagal. La edad media fue 21,45±5,18; con mayor positividad para el género femenino. En el seguimiento, el 10% de los positivos, consultó a urgencias por pérdida de conciencia, 4% fue ingresado a hospitalización y 10% presentó lesiones secundarias. Conclusiones: Un número representativo de participantes fue positivo en la Escala de Calgary, ninguno de ellos había recibido diagnóstico de síncope neuralmente mediado, pese a haber consultado a urgencias y/o presentar lesiones secundarias por pérdida de conciencia. Incluir la Escala de Calgary en la evaluación inicial del paciente consultante por pérdida de conciencia, podría ayudar al diagnóstico temprano de síncope vasovagal.

Abstract Introduction: Vasovagal syncope has an incidence between 10% and 19% in the general population, whose first episodes appear in youth. Objective: To estimate the prevalence of vasovagal syncope in a university student population from the southern Colombia, using a diagnostic questionnaire adapted from the Calgary Scale. Materials and methods: After voluntary signing of the informed consent form, students were surveyed through the Calgary Scale, and a subsequent follow-up questionnaire was conducted on positive participants. Results: 280 students participated in the study and 17% of them obtained a positive score for vasovagal syncope, being positive female participants the largest group. The mean age of participants was 21.45±5.18 years. At the follow-up, 10% of the positive cases had sought out treatment in emergency rooms because of consciousness loss, 4% were hospitalized, and 10% had secondary injuries. Conclusions: Even though an important number of patients was positive on the Calgary Scale, none of them had been diagnosed with neutrally mediated syncope, despite being treated in emergency rooms and/or presenting secondary lesions due to consciousness loss. The use of the Calgary Scale during the assessment of patients being treated for consciousness loss could help to early diagnose vasovagal syncope.

The Role of Beta-1 Receptor Gene Polymorphism in Beta-Blocker Therapy for Vasovagal Syncope

Background: Vasovagal syncope (VVS) is a common clinical condition involving genetic background. The role of beta-blockers in the treatment is controversial. Objective: The aim of this study was to investigate the effect of beta-1 gene polymorphism on beta-blocker therapy in patients with VVS. Methods: We included 123 patients who were diagnosed with VVS after the tilt-table test. We searched for the polymorphism Arg389Gly (rs1801253) in the beta-1 adrenoceptor gene. Results: Overall, 64 patients (52%) had Arg389Arg genotype and 59 patients (48%) had Arg389Gly genotype. The syncopal episodes of patients with Arg389Arg genotype were more frequent compared with patients having Arg389Gly genotype (total syncopal episodes [TSE], 7.9 ± 3.7 vs. 6.4 ± 3.0; p = 0.012). TSE in patients with Arg389Arg genotype decreased significantly after 18 months of beta-blocker treatment (7.9 ± 3.7 vs. 3.0 ± 1.4, p < 0.001). After 18 months of beta-blocker treatment, patients with Arg389Arg genotype had significantly fewer syncopal episodes than patients with Arg389Gly genotype (3.0 ± 1.4 vs. 6.8 ± 3.2, p < 0.001). Conclusions: Results of beta-blocker therapy in patients with Arg389Arg genotype suggest that VVS pathophysiology is a multifactorial condition, with genetic, psychological, and environmental components, and therefore, treatment selection can be based on gene polymorphism. (REV INVEST CLIN. 2020;72(5):300-7)

Pathophysiology and Individualized Management of Vasovagal Syncope and Postural Tachycardia Syndrome in Children and Adolescents: An Update / 神经科学通报·英文版

Vasovagal syncope (VVS) and postural tachycardia syndrome (POTS) are the main forms of orthostatic intolerance in pediatrics and both are underlying causes of neurally-mediated syncope. In recent years, increasing attention has been paid to the management of VVS and POTS in children and adolescents. A number of potential mechanisms are involved in their pathophysiology, but the leading cause of symptoms varies among patients. A few studies thus have focused on the individualized treatment of VVS or POTS based on selected hemodynamic parameters or biomarkers that can predict the therapeutic effect of certain therapies and improve their effectiveness. This review summarizes the latest developments in individualized treatment of VVS and POTS in children and indicates directions for further research in this field.

Polymorphisms in ß-adrenergic receptors are associated with increased risk to have a positive head-up tilt table test in patients with vasovagal syncope

Abstract Background Vasovagal syncope (VVS) is a frequent clinical condition in which a genetic background seems to be implicated. Considering that the adrenergic receptors (ARs) may play a role in VVS, the present study has as principal aim to determine if the α- and β-AR (ADRA and ADRB) gene polymorphisms are associated with an increased risk to have a positive head-up tilt table (HUTT) test in patients with VVS. Methods: Nine polymorphisms in the ADRA1A (rs1048101, rs1383914, rs574584, and rs573542), ADRB1 (rs1801252 and rs1801253), ADRB2 (rs1042713 and rs1042714), and ADRB3 (rs4994) genes were analyzed using the 5’ exonuclease TaqMan genotyping assay in a group of 134 patients with VVS. Results Under different models, the rs1801252 (OR = 8.63, 95% CI: 0.95-78.72, Precessive = 0.02), rs1042713 (OR = 1.94, 95% CI: 1.02-3.66, Padditive = 0.04), and rs4994 (OR = 2.46, 95% CI: 1.01-6.01, Pdominant = 0.042 and OR = 2.62, 95% CI: 1.04-6.63, Pover-dominant = 0.03) polymorphisms were associated with increased risk for a positive HUTT. All models were adjusted for statistically significant covariates. Conclusion These results suggest that some polymorphisms of the β-AR genes could contribute to a positive tilt test in patients with VVS.

Advances in the role of vascular endothelial system in the pathogenesis of vasovagal syncope in children / 临床儿科杂志

Vasovagal syncope (VVS) is the most common cause of unexplained syncope in children. The etiology of VVS is complex, and its diagnosis is mainly based on clinical manifestations and head-up tilt test (HUT) . It has been pointed out that neuroendocrine system plays an important role in the pathogenesis of syncope. HUT-induced syncope is accompanied by abnormal neurohumoral activation. The changes of plasma concentration of endothelin-1 and nitric oxide secreted by endothelial system before and after VVS syncope in children suggest that endothelial system is involved in the occurrence of VVS in children. This article reviews the research on the involvement of vascular endothelial system in the pathogenesis of VVS in children.

Changes in heart rate deceleration capacity and variability in resting children with vasovagal syncope / 中华实用儿科临床杂志

Objective To investigate the changes in heart rate deceleration capacity( DC)and heart rate va-riability(HRV)parameters in children with vasovagal syncope(VVS),to assess the basic autonomic function of children with VVS,and to explore the reference value of DC for the diagnosis of VVS in children. Methods VVS group included 62 patients diagnosed with VVS in the Cardiovascular Department of Children＇s Hospital Affiliated to Capital Institute of Pediatrics from June 2015 to December 2017,56 outpatients undergoing physical examination were selected as the healthy control group,and the changes in DC and HRV matched to age and gender were analyzed respectively. Indexes of DC and HRV of both groups of children in health control group and children with VVS were compared among different age groups or different genders. Results (1)Analysis of DC and HRV based on age or gender:whether in healthy children or in children with VVS,DC and HRV parameters varied significantly in the range of different ages,while they were the same in children with different genders.(2)Comparison of DC and HRV in school-age and puberty children between VVS group and healthy control group:in school-aged children,DC of VVS group was significantly higher than that of healthy control group[(6. 8 ± 1. 0)ms υs.(6. 0 ± 0. 7)ms,t= -2. 412,P<0. 01]. Mean square root rates of succe-ssive normal sinus RR interval differences(rMSSD)increased,and the difference was significant( P<0. 05). In chil-dren at puberty,DC in children of VVS group was significantly higher than that in the healthy control group[(7. 4 ± 1. 2)ms υs.(6. 6 ± 1. 1)ms,t= -2. 742,P<0. 01],rMSSD,LF and HF value were significantly higher compared with those of the healthy control group(all P<0. 05).(3)Predictive value of DC on VVS:the binary Logistic regression analysis found that only DC was associated with VVS in different age groups. By using receiver operating characteristic curve to analyze the predictive value of DC on VVS,it was found that when making DC 6. 5 ms for school age and 7. 0 ms at puberty as the threshold,a better prediction of VVS could be achieved with good sensitivity and specificity. Conclusions Children＇s autonomic nervous function changes with age,and DC and HRV parameters change signifi-cantly during adolescence and at school age. Children with VVS may have abnormally increased vagal tone. When DC≥6. 5 ms at school age or DC≥7. 0 ms at puberty,it may have a reference value for the diagnosis of VVS.

Changes in heart rate deceleration capacity and variability in resting children with vasovagal syncope / 中华实用儿科临床杂志

Objective@#To investigate the changes in heart rate deceleration capacity(DC) and heart rate va-riability(HRV) parameters in children with vasovagal syncope(VVS), to assess the basic autonomic function of children with VVS, and to explore the reference value of DC for the diagnosis of VVS in children.@*Methods@#VVS group included 62 patients diagnosed with VVS in the Cardiovascular Department of Children′s Hospital Affiliated to Capital Institute of Pediatrics from June 2015 to December 2017, 56 outpatients undergoing physical examination were selected as the healthy control group, and the changes in DC and HRV matched to age and gender were analyzed respectively.Indexes of DC and HRV of both groups of children in health control group and children with VVS were compared among different age groups or different genders.@*Results@#(1)Analysis of DC and HRV based on age or gender: whether in healthy children or in children with VVS, DC and HRV parameters varied significantly in the range of different ages, while they were the same in children with different genders.(2)Comparison of DC and HRV in school-age and puberty children between VVS group and healthy control group: in school-aged children, DC of VVS group was significantly higher than that of healthy control group [(6.8±1.0) ms vs.(6.0±0.7) ms, t=-2.412, P<0.01]. Mean square root rates of succe-ssive normal sinus RR interval differences(rMSSD) increased, and the difference was significant (P<0.05). In children at puberty, DC in children of VVS group was significantly higher than that in the healthy control group [(7.4±1.2) ms vs.(6.6±1.1) ms, t=-2.742, P<0.01], rMSSD, LF and HF value were significantly higher compared with those of the healthy control group (all P<0.05). (3)Predictive value of DC on VVS: the binary Logistic regression analysis found that only DC was associated with VVS in different age groups.By using receiver operating characteristic curve to analyze the predictive value of DC on VVS, it was found that when making DC 6.5 ms for school age and 7.0 ms at puberty as the threshold, a better prediction of VVS could be achieved with good sensitivity and specificity.@*Conclusions@#Children′s autonomic nervous function changes with age, and DC and HRV parameters change significantly during adolescence and at school age.Children with VVS may have abnormally increased vagal tone.When DC ≥6.5 ms at school age or DC≥7.0 ms at puberty, it may have a reference value for the diagnosis of VVS.

Changes in creatine kinase and its isoenzymes in children and adolescents with vasovagal syncope / 中华实用儿科临床杂志

Objective To investigate the changes in creatine kinase (CK) and its isoenzymes (CK-MB) in children and adolescents with vasovagal syncope (VVS).Methods The VVS group included 150 patients with unexplained syncope or prodromata[69 males and 81 females,aged from 4 to 17 years old,with the average age (11.21 ±2.40) years old],who had been diagnosed as VVS by using head-up tilt table test(HUTT) in the Second Xiangya Hospital,Central South University from October 2015 to August 2017.The healthy control group included 99 healthy children [58 males and 41 females,aged from 4 to 17 years old,with the average age (10.78 ± 2.26)years old] with gender and age-matched.The differences in serum CK and CK-MB levels between 2 groups were compared,and receiver operating characteristic (ROC) curve was used to explore the predictive value of CK and CK-MB for diagnosing VVS.Results (1) Compared with the healthy control group,both CK [(93.77 ± 33.01) U/L vs.(125.02 ± 58.06) U/L] and CK-MB [(21.31 ± 6.99) U/L vs.(26.93 ± 8.78) U/L] levels decreased in the VVS group,and there were statistically significant differences(all P ＜0.05).When the value of CK was 89.22 U/L,the sensitivity to diagnostic VVS was 76.80％,and the specificity was 54.70％;while the value of CK-MB was 23.93 U/L,the sensitivity to diagnostic VVS was 66.70％,and the specificity was 71.30％.(2) In VVS group,the CK levels of the females were significantly lower than those of the males [(85.25 ± 29.43) U/L vs.(103.77 ± 34.36) U/L],and there was a statistical difference (P ＜ 0.05);while there was no significant difference in CK-MB between the males and the females in VVS group.(3) There were no significant differences between 3 types of VVS (all P＞0.05).Compared with the healthy control group,CK decreased in all the 3 types of VVS (all P ＜ 0.05),while CK-MB decreased only in the vasodepressor type and mixed type (all P ＜ 0.05).Conclusions Compared with the healthy children and adolescents,the serum CK and CK-MB levels will decrease in children with VVS,which indicates that CK and CK-MB may be involved in the pathogenesis of VVS.

Research progress of mechanisms for vasovagal syncope in children / 中华实用儿科临床杂志

Vasovagal syncope(VVS),with its relatively high morbidity,is one of the most common types of au-tonomic-mediated reflex syncope in children,which can seriously affect pediatric patients in their life and study.A se-ries of research have shown that the mechanism for VVS is closely related to autonomic nervous imbalance,neurohor-monal factor,and cerebral blood flow abnormality,and has a certain degree of genetic tendency.Now the progress in the mechanisms for VVS at home and abroad is reviewed,in order to provide certain help for further research.

Diagnostic value of head-up tilt test in patients with cough syncope / 重庆医学

Objective To investigate the diagnostic value of head-up tilt test (HUT) in cough syncope (CS).Methods Forty-seven outpatients or inpatients with CS and 79 patients with suspected vasovagal syncope(SVVS) due to syncope history in our hospital from January 2011 to May 2015 served as the observation group and control group respectively.HUT was performed in the two groups.The cough response during HUT,changes of systolic pressure and diastolic pressure caused by cough,HUT positive results and hemodynamic type were observed,Results In the observation group,4 cases(8.51％) were cough caused syncope,26 cases (55.32 ％) were presyncope and 17 cases (36.17 ％) had no symptoms,while 79 cases in the control group had no symptoms,the differences were statistically significant (P＜ 0.05).The total positive rate of cough response in the observation group was 63.83％,and the specificity was 100.00％.The systolic blood pressure had statistical difference between the two groups(.P＜0.05).The diastolic pressure had statistical difference between the cases of non-symptoms with the cases of syncope and cases of presyncope in the observation group (P＜0.05),but had no statistical difference compared with the cases of non-symptoms in the control group(P＞0.05).The heart rate(HR) had no statistical difference among various groups(P＞0.05).The HUT positive rate in the observation group was lower than that in the control group(P＜0.05).The hemodynamic type had no statistical difference between the two groups(P＞0.05).Conclusion Severe coughing during HUT may cause the blood pressure decrease,induces syncope or presyncope,can increase the diagnostic sensitivity of CS patients,which is very useful in the suspected diagnosis of CS patients,especially for CS patients with a unclear history.

Diagnostic value of head-up tilt test in patients with cough syncope / 重庆医学

Objective To investigate the diagnostic value of head-up tilt test (HUT) in cough syncope (CS).Methods Forty-seven outpatients or inpatients with CS and 79 patients with suspected vasovagal syncope(SVVS) due to syncope history in our hospital from January 2011 to May 2015 served as the observation group and control group respectively.HUT was performed in the two groups.The cough response during HUT,changes of systolic pressure and diastolic pressure caused by cough,HUT positive results and hemodynamic type were observed,Results In the observation group,4 cases(8.51％) were cough caused syncope,26 cases (55.32 ％) were presyncope and 17 cases (36.17 ％) had no symptoms,while 79 cases in the control group had no symptoms,the differences were statistically significant (P＜ 0.05).The total positive rate of cough response in the observation group was 63.83％,and the specificity was 100.00％.The systolic blood pressure had statistical difference between the two groups(.P＜0.05).The diastolic pressure had statistical difference between the cases of non-symptoms with the cases of syncope and cases of presyncope in the observation group (P＜0.05),but had no statistical difference compared with the cases of non-symptoms in the control group(P＞0.05).The heart rate(HR) had no statistical difference among various groups(P＞0.05).The HUT positive rate in the observation group was lower than that in the control group(P＜0.05).The hemodynamic type had no statistical difference between the two groups(P＞0.05).Conclusion Severe coughing during HUT may cause the blood pressure decrease,induces syncope or presyncope,can increase the diagnostic sensitivity of CS patients,which is very useful in the suspected diagnosis of CS patients,especially for CS patients with a unclear history.

Epicardial Fat Thickness is Correlated with Vagal Hyperactivity in Patients with Neurally-Mediated Syncope

BACKGROUND: Epicardial fat tissue has unique endocrine and paracrine functions that affect the cardiac autonomic system. The head-up tilt test (HUTT) is a simple non-invasive measurement that assesses autonomic nervous system dysfunction. We investigated the association between epicardial fat thickness (EFT) and autonomic neural tone, such as vagal tone. METHODS: A total of 797 consecutive patients (mean age 46.5 years, male: 45.7%) who underwent HUTT and echocardiography between March 2006 and June 2015 were enrolled. EFT was measured during the diastolic phase of the parasternal long axis view. We excluded patients with prior percutaneous coronary intervention, old age (* 70 years old), valvular heart disease, symptomatic arrhythmias and diabetes. We divided patients into two groups based on the HUTT (positive vs. negative). RESULTS: There were 329 patients (41.3%) with a negative HUTT result and 468 patients (58.7%) with a positive result. The HUTT-positive patients showed a significantly lower waist circumference, body mass index and systolic and diastolic blood pressure, although a significantly higher EFT as compared to the HUTT-negative patients (HUTT-positive, 5.69 ± 1.76 mm vs. HUTT-negative, 5.24 ± 1.60 mm; p 5.4 mm was associated with a positive HUTT result with 51.7% sensitivity and 63.8% specificity (p < 0.001) on receiving operator characteristic analysis. Multivariate Cox regression analysis revealed that EFT (hazard ratio: 1.02, 95% confidence interval: 1.01–1.30, p = 0.004) was an independent predictor of HUTT-positivity. CONCLSION: EFT was significantly correlated with positive HUTT, which suggests an association between EFT and autonomic dysregulation.

Deceleration Capacity—A Novel Measure for Autonomic Nervous System in Patients with Vasovagal Syncope on Tilt-table Testing / 华中科技大学学报（医学）（英德文版）

This study was to investigate the changes of autonomic nerve function and hemodynamics in patients with vasovagal syncope (VVS) during head-up tilt-table testing (HUT).HUT was performed in 68 patients with unexplained syncope and 18 healthy subjects served as control group.According to whether bradycardia,hypotension or both took place during the onset of syncope,the patients were divided during the test into three subgroups:vasodepressor syncope (VD),cardioinhibitory syncope (CI) and mixed syncope (MX) subgroups.Heart rate,blood pressure,heart rate variability (HRV),and deceleration capacity (DC) were continuously analyzed during HUT.For all the subjects with positive responses,the normalized low frequency (LFn) and the LF/HF ratio markedly decreased whereas normalized high frequency (HFn) increased when syncope occurred.Syncopal period also caused more significant increase in the power of the DC in positive groups.These changes were more exaggerated compared to controls.All the patients were indicative of a sympathetic surge in the presence of withdrawal vagal activity before syncope and a sympathetic inhibition with a vagal predominance at the syncopal stage by the frequency-domain analysis of HRV.With the measurements ofDC,a decreased vagal tone before syncope stage and a vagal activation at the syncopal stage were observed.The vagal tone was higher in subjects showing cardioinhibitory responses at the syncopal stage.DC may provide an alternative method to understand the autonomic profile of VVS patients.