Vasovagal Syncope In Children Research Articles

Efficacy of catheter ablation in ganglionated plexus for malignant vasovagal syncope children.

Malignant vasovagal syncope in children seriously affects their physical and mental health. Our study aimed to explore the efficacy of catheter ablation in ganglionated plexus with malignant vasovagal syncope children. Catheter ablation of ganglionated plexus was safe and effective in children with malignant vasovagal syncope and can be used as a treatment option for these children. A total of 20 children diagnosed with malignant vasovagal syncope were enrolled in Beijing Children's Hospital, affiliated with Capital Medical University. All underwent catheter ablation treatment of ganglionated plexus. Ganglionated plexuses of the left atrium were identified by high-frequency stimulation and/or anatomic landmarks being targeted by radiofrequency catheter ablation. The efficacy of the treatment was evaluated by comparing the remission rate of post-operative syncopal symptoms and the rate of negative head-up tilt results. Safety and adverse events were evaluated. After follow-up for 2.5 (0.6-5) years, the syncope symptom scores were decreased significantly compared with before treatment [3 (2-4) versus 5 (3-8) scores, P < 0.01]. Eighty-five per cent (17/20) children no longer experienced syncope, whilst 80% (16/20) children showed negative head-up tilt test after treatment. No adverse effects such as cardiac arrhythmia occurred in the children.

Serum uric acid predicts therapeutic response to midodrine hydrochloride in children with vasovagal syncope: a pilot study

Serum uric acid (UA) level has been proven to be related to several cardiovascular and metabolic diseases. In the present study, we examined if baseline serum UA level could predict the therapeutic efficacy of midodrine hydrochloride on vasovagal syncope (VVS) in children. The pediatric VVS patients who received midodrine hydrochloride from November 2008 to October 2022 were enrolled. After a median treatment duration of 3 months, the therapeutic effect was evaluated. According to the patients’ responses to midodrine hydrochloride, which was determined by the recurrence of syncope, they were divided into effective and ineffective groups. The baseline variables were explored using univariable and multivariate logistic analysis. The predictive efficacy was assessed by receiver operating characteristic curve (ROC), precision-recall curve (PR), Hosmer–Lemeshow test, calibration curve, and decision curve analysis (DCA). Totally, 53 participants were included in the study. Among the 51 patients who were successfully followed up, 29 (56.9%) responded to midodrine hydrochloride (effective group), and the other 22 (43.1%) failed to respond to midodrine hydrochloride (ineffective group). The participants in effective group had lower baseline serum UA level than those in ineffective group (276.5 ± 73 μmol/L vs. 332.7 ± 56 μmol/L, p = 0.004). Multivariable logistic analysis showed that serum UA was associated with the therapeutic response (odds ratio (OR): 0.985, 95% confidence interval (CI): 0.974–0.997, p = 0.01). ROC analysis indicated that using baseline serum UA < 299 μmol/L as a threshold value yielded a sensitivity of 77.3% and a specificity of 79.3% in predicting the treatment response to midodrine hydrochloride. The area under the PR curve was 0.833. Hosmer–Lemeshow test yielded a p value of 0.58, and calibration plot indicated that the model was well-fitted. DCA demonstrated that treatment decision depending on the baseline serum UA level resulted in a favorable net benefit. Conclusion: This pilot study suggested that the baseline serum UA level could be taken as a predictor of therapeutic effect of midodrine hydrochloride on VVS in children.What is Known:• Empirical and unselected use of midodrine hydrochloride has an unfavorable therapeutic effect on VVS in children. Serum uric acid (UA) is closely linked to cardiovascular events.What is New:• A low baseline serum UA level successfully predicts the therapeutic effectiveness of midodrine hydrochloride on VVS in children.

Markers for predicting the efficacy of beta-blockers in vasovagal syncope management in children: A mini-review.

Vasovagal syncope (VVS) is a common subtype of neurally mediated syncope. It is prevalent in children and adolescents, and critically affects the quality of life of patients. In recent years, the management of pediatric patients with VVS has received extensive attention, and β-blocker serves as an important choice of the drug therapy for children with VVS. However, the empirical use of β-blocker treatment has limited therapeutic efficacy in patients with VVS. Therefore, predicting the efficacy of β-blocker therapy based on biomarkers related to the pathophysiological mechanism is essential, and great progress has been made by applying these biomarkers in formulating individualized treatment plans for children with VVS. This review summarizes recent advances in predicting the effect of β-blockers in the management of VVS in children.

Risk factors associated with malignant vasovagal syncope in children

Objective: To analyze the clinical characteristics and risk factors of malignant vasovagal syncope (VVS) in children. Methods: This was a case-control study. The data of 368 VVS patients who were treated in the Department of Cardiology, Children's Hospital, Capital Institute of Pediatrics from June 2017 to December 2021 was collected and analyzed. They were divided into malignant VVS group and non-malignant VVS group according to the presence of sinus arrest, and then their demographic characteristics were compared. The children with malignant VVS and complete clinical information were recruited into the case group and were matched by age and sex (1∶4 ratio) with non-malignant VVS patients during the same period.Their clinical characteristics and lab tests were compared. Independent sample t test, Mann Whitney U or χ2 test was used for comparison between groups.Logistic regression was used to analyze the risk factors for malignant VVS in children. Results: Eleven malignant VVS and 342 non-malignant VVS met the inclusion and exclusion critera. Eleven malignant VVS and 44 non-malignant children were recruited in the case-control study. Ten patients of the 11 malignant VVS had a cardiac arrest occurring at 35 (28, 35) minutes of the head-up tilt test, and the duration of sinus arrest was (9±5) s. One patient had syncope occurring while waiting for drawing blood, and the duration of sinus arrest was 3.4 s. The children with malignant vasovagal syncope were younger than non-malignant VVS patients (9 (7, 10) vs. 12 (10, 14) years old, P<0.05), and had higher mean corpuscular hemoglobin concentration (MCHC) and standard deviation of the mean cardiac cycle over 5-minute period within 24 hours ((347±9) vs. (340±8) g/L, (124±9) vs. (113±28) ms, both P<0.05). Logistic regression analysis showed that MCHC was an independent risk factor for malignant VVS in pediatric patients (OR=1.13, 95%CI 1.02-1.26, P=0.024). Conclusions: The onset age of malignant VVS was younger, with no other special clinical manifestations. MCHC was an independent risk factor for malignant VVS.

Predictive value of blood cell parameters in the diagnosis of vasovagal syncope in children

Objective: To investigate the predictive value of blood cell parameters in children with vasovagal syncope (VVS). Methods: In this case-control study, the VVS group included 111 patients with unexplained syncope or prodromata who were diagnosed with VVS by head-up tilt test in the Second Xiangya Hospital, Central South University from January 2018 to October 2020, and 111 healthy children were enrolled as control. The differences in blood cell parameters between the 2 groups were compared by t test and Mann-Whitney U test. Multivariate binary Logistic regression was used to analyze the independent correlation factors of VVS, and receiver operating characteristic (ROC) curve to explore the predictive value of blood cell parameters for diagnosing VVS. Results: Sex composition ratios were consistent in the 2 groups (51 males vs. 60 females), while the age of the VVS group was higher than that of the control group (11.0 (8.0, 12.5) vs. 8.0 (7.0, 11.0) years, Z=4.39, P<0.001). Compared with the control group, VVS group had lower level of white blood cell (WBC) (6.0 (5.3, 7.1)×109 vs. 8.6 (6.7, 10.1)×109/L, Z=-7.96, P<0.001), lymphocyte (LY) (2.3 (1.9, 2.7)×109 vs. 4.0 (2.8, 6.3)×109/L, Z=-8.49, P<0.001), lymphocyte ratio (0.39 (0.33, 0.44) vs. 0.52 (0.37, 0.69), Z=-5.59, P<0.001), monocyte (0.3 (0.3, 0.4)×109 vs. 0.4 (0.3, 0.6)×109/L, Z=-6.19, P<0.001), eosinophil (0.1 (0.1, 0.2)×109 vs. 0.2 (0.2, 0.4)×109/L, Z=-5.75, P<0.001), mean corpuscular-hemoglobin concentration (MCHC) ((328±12) vs. (333±11) g/L, t=-3.27, P<0.001) and blood platelet (263 (235, 313)×109 vs. 341 (295, 409)×109/L, Z=-2.69, P<0.001), but higher neutrophil ratio (0.53 (0.48, 0.58) vs. 0.37 (0.22, 0.54), Z=5.86, P<0.001), hematocrit (0.39±0.04 vs. 0.37±0.04, t=2.75, P=0.006), mean corpuscular volume (MCV) (85 (82, 88) vs. 81 (78, 84) fl, Z=5.56, P<0.001), mean corpuscular hemoglobin (28 (27, 29) vs. 27 (26, 28) pg, Z=3.39, P=0.001), red cell distribution width (39 (37, 41) vs. 37 (36, 40) fl, Z=4.02, P<0.001) and mean platelet volume (11 (10, 11) vs. 10 (9, 11) fl, Z=2.81, P=0.005) levels. After adjusting for confounding factors such as sex and age, LY (OR=0.42, 95%CI 0.29-0.62, P<0.001), WBC (OR=0.75, 95%CI 0.59-0.95, P=0.015), MCHC (OR=0.94, 95%CI 0.91-0.97, P<0.001) were independent negative correlation factors of VVS, while MCV (OR=1.08, 95%CI 1.01-1.15, P=0.021) was independent positive correlation factor. ROC curve showed that the combination of LY, WBC, MCV and MCHC had acceptable predictive value for the diagnosis of VVS, with area under curve of 0.88, sensitivity of 0.80, specificity of 0.83, and Youden index of 0.63. Conclusions: Compared with healthy children, the blood cell parameters usually change in those with VVS. Combination of LY, WBC, MCHC and MCV can facilitate the diagnosis of VVS in children with unexplained syncope or prodromata.

Clinical Efficacy of Empirical Therapy in Children with Vasovagal Syncope.

(1) Background: This case-control study was designed to assess the efficacy of empiric treatment for vasovagal syncope in children; (2) Methods: We retrospectively enrolled 181 children with vasovagal syncope from the Department of Pediatrics of Peking University First Hospital. The participants were categorized into four groups, based on the empiric treatment received: conventional treatment, including health education and orthostatic training; conventional treatment plus oral rehydration salts; conventional treatment plus metoprolol; conventional treatment plus midodrine hydrochloride. Patients were followed up to evaluate the syncopal or presyncopal recurrence. Kaplan–Meier curves were drawn to explore the syncopal or presyncopal recurrence in children, and the differences were compared among the groups using a log-rank test; (3) Results: Among the 181 children with vasovagal syncope, 11 were lost to follow-up. The median time of follow-up was 20 (8, 42) months. The Kaplan–Meier survival curve showed no significant difference in syncopal or presyncopal recurrence in children treated with different empiric options according to a log-rank test (χ2 = 1.328, p = 0.723); (4) Conclusions: The efficacy of unselected empiric therapy of vasovagal syncope in children was limited, and the individualized therapies merit further studies.

The Diagnosis and Management of Vasovagal Syncope in Pediatric Patients

Vasovagal syncope is the most common cause of syncope in pediatric patients. The present study is aim to provide a comprehensive literature review of the latest advances in the diagnosis and treatment of vasovagal syncope in children. Diagnosis of vasovagal syncope is based on clinical history. For patients with suspected VVS but lack of confident diagnosis after initial assessment, head-up tilt test is helpful. There are four options for treatment of vasovagal syncope: conservative therapy, pharmacologic therapy, pacemaker therapy, and catheter ablation of ganglionated plexi. Conservative therapy (health education, avoidance of triggers, salts and water intake, physical countermeasures and orthostatic training) is recommended for patients with occasional syncope. Pharmacological therapy should be considered for patients with recurrent syncope or for whom conservative therapy has failed. Patients with the predominantly cardioinhibitory response, associated with repeated injury, limited prodromes, and documented asystole may benefit from cardiac pacing. Catheter ablation of ganglionated plexi is a new strategy, its efficacy and safety in pediatric patients should be verified by randomized controlled trials.

Differential Diagnosis Between Psychogenic Pseudosyncope and Vasovagal Syncope in Children: A Quantitative Scoring Model Based on Clinical Manifestations.

The study was designed to explore a clinical manifestation-based quantitative scoring model to assist the differentiation between psychogenic pseudosyncope (PPS) and vasovagal syncope (VVS) in children. In this retrospective case-control study, the training set included 233 pediatric patients aged 5–17 years (183 children with VVS and 50 with PPS) and the validation set consisted of another 138 patients aged 5–15 years (100 children with VVS and 38 with PPS). In the training set study, the demographic characteristics and clinical presentation of patients were compared between PPS and VVS. The independent variables were analyzed by binary logistic regression, and the score for each variable was given according to the approximate values of odds ratio (OR) to develop a scoring model for distinguishing PPS and VVS. The cut-off scores and area under the curve (AUC) for differentiating PPS and VVS cases were calculated using receiver operating characteristic (ROC) curve. Then, the ability of the scoring model to differentiate PPS from VVS was validated by the true clinical diagnosis of PPS and VVS in the validation set. In the training set, there were 7 variables with significant differences between the PPS and VVS groups, including duration of loss of consciousness (DLOC) (p < 0.01), daily frequency of attacks (p < 0.01), BMI (p < 0.01), 24-h average HR (p < 0.01), upright posture (p < 0.01), family history of syncope (p < 0.05) and precursors (p < 0.01). The binary regression analysis showed that upright posture, DLOC, daily frequency of attacks, and BMI were independent variables to distinguish between PPS and VVS. Based on the OR values of each independent variable, a score of 5 as the cut-off point for differentiating PPS from VVS yielded the sensitivity and specificity of 92.0% and 90.7%, respectively, and the AUC value was 0.965 (95% confidence interval: 0.945–0.986, p < 0.01). The sensitivity, specificity, and accuracy of this scoring model in the external validation set to distinguish PPS from VVS were 73.7%, 93.0%, and 87.7%, respectively. Therefore, the clinical manifestation-based scoring model is a simple and efficient measure to distinguish between PPS and VVS.

Diagnosis and treatment of malignant vasovagal syncope in children

恶性血管迷走性晕厥主要是指反复发作且伴有发作时持续3 s以上心脏停搏的血管迷走性晕厥，对儿童身心健康造成严重危害。然而，目前对其诊断与治疗认识不足。本文强调重视恶性血管迷走性晕厥的诱发因素与临床表现，正确识别儿童恶性血管迷走性晕厥，综述其治疗现状、争议以及今后的发展趋势。.

Тернопольский национальный медицинский университет имени И.Я. Горбачевского Министерства здравоохранения Украины, г. Тернополь, Украина

Актуальность. Результаты последних научных исследований позволяют предположить, что витамин D может оказывать косвенное, а в некоторых случаях и прямое действие в патогенезе вазовагальных синкопе у детей. Цель исследования: изучить уровни витамина D в сыворотке крови детей с вазовагальными синкопе. Материалы и методы. Основную группу составили 30 детей в возрасте 8–17 лет с как минимум одним эпизодом вазовагального синкопе в течение последнего месяца. В контрольную группу вошли 24 практически здоровых ребенка. 25(ОН)D в сыворотке крови определяли методом иммуноферментного анализа с использованием тест-системы Monobind (США). Оценку витамин-D-статуса осуществляли в соответствии с практическими рекомендациями по добавкам витамина D и лечению дефицита в Центральной Европе: дефицит — &lt; 20 нг/мл; субоптимальный уровень (недостаточность) — 20–30 нг/мл; оптимальный уровень — 30–50 нг/мл; высокое содержание — 50–100 нг/мл; опасный уровень — &gt; 100 нг/мл. Результаты. Дети обеих групп были сопоставимы по результатам демографических и клинических показателей, что позволило нивелировать влияние пола, возраста, дефицита и избыточной массы тела, ожирения или артериальной гипертензии на уровень 25(ОН)D. Показатель 25(ОН)D в группе вазовагальных синкопе составил 19,17 ± 1,33 нг/мл и был достоверно ниже по сравнению со здоровыми детьми — 30,91 ± 1,20 нг/мл (р = 0,000001). Оптимальный уровень витамина D регистрировали только у 6,7 % больных с вазовагальными синкопе, тогда как дефицит и недостаточность витамина D — у 33,3 и 60,0 %. Показатели кальция, фосфора и щелочной фосфатазы в сыворотке крови обследованных обеих групп не отличались (p &gt; 0,05). Выводы. У 93,3 % детей с вазовагальными синкопе наблюдается достоверное снижение уровня 25(OH)D в сыворотке крови. Распространенность дефицита витамина D составляет 60,0 %, субоптимального уровня 25(ОН)D — 33,3 %. Дефицит и недостаточность витамина D ассоциируются с сохранением традиционных показателей кальций-фосфорного гомеостаза в пределах референтных значений.

Analysis of risk factors for vasovagal syncope in children

Objective To analyze the related factors of the onset of vasovagal syncope (VVS) in children, and to provide basis for the early prevention, early diagnosis and early treatment of VVS. Methods A total of 126 children with syncope admitted to Department of Pediatric Cardiology, Second Hospital of Lanzhou University from October 2018 to September 2019 were invited in the study. Totally 73 cases of children diagnosed with VVS by HUTT were selected as VVS group, and 53 HUTT-negative children were selected as control group. Related factors were retrospectively investigated, and risk factors for VVS were analyzed by univariate and multivariate regression. Results The VVS group showed statistically significant difference in age distribution with the control group (χ 2 = 19.22, P<0.05). The VVS group showed statistically significant differences of proportion in family history, syncope history, prolonged standing, electrocardiogram abnormalities, and vitamin D deficiency (43.84%, 31. 51%, 47. 95%, 34. 25%, 30.14%) compared with the control group (15.09%, 13.21%, 20.75%, 15.09%, 9.43%) (χ 2 = 11.71, 5.67, 9.79, 5.83, 7.82, P<0.05). Multivariate Logistic regression analysis showed that age and family historywere risk factors for VVS (χ 2 = 3.13, 11.06, P<0.05). Conclusion Age and family history may be risk factors for the onset of VVS. Active attention should be paid to the high-risk factors of child patient, early identification and diagnosis can prevent the occurrence and development of VVS in children. 【摘要】 目的 分析儿童血管迷走性晕厥 (VVS) 发作的相关因素, 为 VVS 早期预防、早期诊断、早期治疗提供一定的依 据。 方法 收集 2018 年 10 月至 2019 年 9 月在兰州大学第二医院小儿心血管科住院的 126 例晕厥患儿为研究对象, 经直 立倾斜试验 (HUTT) 确诊为血管迷走性晕厥 73 例儿童为 VVS 组, 另外 53 例儿童为对照组, 回顾性调査其相关因素。 结果 VVS 组与比较组在年龄分布上差异有统计学意义 (χ 2 = 12.22, P<0.05), VVS 组有家族史、有晕厥史、有持久站立诱因、心电 图异常、维生素 D 缺乏构成比 (43.84%, 31.51%, 47.95%, 34.25%, 30.14%) 与对照组 (15.09%, 13.21%, 20.75%, 15.09%, 9.43%) 比较, 差异均有统计学意义 (χ 2 值分别为 11.71, 5.67, 9.79, 5.83, 7.82, P 值均<0.05)。多因素 Logistic 回归分析显 示, 年龄、家族史与患 VVS 呈正相关 ( OR 值分别为 3.13, 11.06, P 值均<0.05)。 结论 年龄、家族史与 VVS 的发作相关。应积极关注患儿髙危因素, 早识别、早诊断, 以预防儿童 VVS 的发生发展。

The predictive value of urine specific gravity in the diagnosis of vasovagal syncope in children and adolescents

BackgroundVasovagal syncope (VVS) is a kind of common neurally mediated syncope in children and adolescents. Decreased blood volume is one of the pathogenesis of VVS. The diagnosis of VVS is mainly based on head-up tilt test (HUTT), but some complications may easily occur when HUTT induces syncope. To find a simple and safe VVS diagnosis method can improve the VVS diagnosis efficiency.Aims of the studyThis was a prospective study. The study will explore the predictive value of urine specific gravity (USG) in the diagnosis of VVS in children and adolescents.Patients and methodsNinety-seven cases (43 males and 54 females, aged 4 to 16 years old, with an average age of 10.91 ± 2.18 years old) hospitalized due to unexplained premonitory syncope or syncope and diagnosed with VVS through HUTT from September 2014 to September 2018 were selected as VVS group. During the same period, 91 cases of children and adolescents, including 45 males and 46 females, aged from 5 to 15 years old, who underwent a healthy examination were matched as a control (control group). USG was measured in both groups.ResultsThe USG of VVS group was significantly lower than that of the control group (P < 0.01), and USG of females was lower than that of males in VVS group (P = 0.045). The sensitivity and specificity of USG in predicting VVS were evaluated by ROC curve. The area under the ROC curve was 0.751, standard error was 0.035, and 95% CI (0.683, 0.819) suggested that USG was of moderate predictive value in the diagnosis of VVS. As cut-off value of USG was 1.0185, the sensitivity and specificity and diagnostic coincidence rate of VVS were 74.39, 66.04 and 69.68%, respectively.ConclusionThere are less USG in children and adolescents with VVS, especially lower USG in females. Therefore, USG has predictive value in the diagnosis of VVS in children and adolescents.

Vitamin D Deficiency and Vasovagal Syncope in Children and Adolescents.

Aims: To investigate the association of vitamin D deficiency with cardiovascular autonomic nervous system function in children and adolescents with vasovagal syncope (VVS).Methods: This study recruited 76 pediatric patients with VVS and 15 healthy children. The 25-hydroxyvitamin D levels in serum among the participants were evaluated. Heart rate variability analysis including SDNN, rMSSD, and SDANN was tested in patients with VVS. The correlation between indices of time-domain analysis and serum vitamin D status of the children with VVS was investigated.Results: In this work, 25-hydroxyvitamin D levels in serum among VVS cases remarkably decreased compared with those among healthy controls (48.76 ± 19.25 vs. 67.62 ± 15.46 nmol/L, p < 0.01). The vitamin D deficient patients with VVS exhibited a lower rMSDD value compared to the non-deficient group with VVS (45.56 ± 16.87 vs. 61.90 ± 20.38 ms, p < 0.001, respectively). Pearson correlation analysis indicated that serum 25-hydroxyvitamin D levels had positive correlation with rMSDD values (r = 0.466, p < 0.001).Conclusions: As suggested by our data, VVS children and adolescents with vitamin D deficiency may have cardiac autonomic dysfunction and cardiac vagal tone decreases with the reduction in vitamin D level.

83 Electrocardiogram in Syncope: An old habit or clinically helpful?

Abstract Background Syncope affects up to 50% of individuals by age 21 years and accounts for 1% of presentations to the emergency department (ED). Cardiac causes of syncope, including structural heart defects and rhythm disorders, cannot always be ruled out by an electrocardiogram (ECG) as this test lacks sensitivity and specificity. Conflicting recommendations for the role of ECG in evaluation of pediatric syncope underscore the clinical equipoise of how ECG findings influence physicians’ clinical decisions. Objectives The primary objective of this study is to determine how ECG findings affect ED physicians’ management of children presenting with vasovagal syncope. Our secondary objective is to document the practice pattern variation among ED physicians regarding their decision to obtain an ECG for the evaluation of vasovagal syncope in children. Design/Methods We conducted a prospective cross-sectional survey study using the REDCap platform. Our sample frame consisted of practicing emergency physicians enrolled in the Pediatric Emergency Research Canada (PERC) network. Outcome measures included frequency investigations, specialist consultation, and disposition stratified by type of syncope presentation (low/high risk). We also evaluated which specific ECG findings were likely to change physicians’ management and explored factors influencing the decision to perform or not perform the ECG. Results We obtained data from 105/225 (47%) potential respondents. In a clinical scenario presenting a vasovagal syncope, 52% of respondents would order an ECG. Forty-five percent changed their management if the ECG interpretation was anything other than “Normal ECG”. In a high-risk syncope scenario, an ECG was performed by 96% of respondents. Cardiology referral was requested by 93% of respondents, despite normal ECG findings. Borderline ECG findings led to significant practice variation in management, for both low and high-risk presentations scenarios. Overall, 66% of respondents stated that performing an ECG is not important to rule out a cardiac etiology in a typical vasovagal syncope presentation, but 64% stated that performing an ECG is important to reassure the patient. Conclusion There is substantial practice pattern variation among emergency physicians with regards to the frequency and motivations to order ECGs, and how ECG findings impact the management of pediatric syncope in the ED. Information provided by an ECG can lead to unnecessary change to clinical management, additional testing, and referrals to specialists for typical vasovagal syncope. This reinforces the importance of better knowledge translation surrounding evidence-based management of vasovagal syncope among ED physicians.

Advance in the understanding of vasovagal syncope in children and adolescents.

Vasovagal syncope (VVS) accounts for 60-80% of cases of neurally mediated syncope. VVS results from acute orthostatic intolerance and recurrent syncopal attacks, which can seriously affect an individual's quality of life. In addition, some children even experience trauma during attacks. Therefore, it is particularly important to clarify the pathogenesis of VVS. The aim of our study is to reveal the latest research progress of VVS. Literature that involved the pathogenesis of VVS were selected from Cochrane Library (1990-2019), EMBASE (1991-2019) and PubMed (1968-2019) databases. Hypovolemia, autonomic dysfunction, vasomotor dysfunction, baroreceptor reflex abnormalities, endothelial dysfunction, serotonin surges, and gut microbiota were involved in the underlying mechanism of VVS. VVS is not always a benign prognosis. Various aspects were involved in its pathogenesis. Bezold-Jarish reflex, dysfunction of the autonomic nervous system, genetic factors and so on played important roles in VVS; however, the mechanism remains unclear.

Reduced 24-h Sodium Excretion Is Associated With a Disturbed Plasma Acylcarnitine Profile in Vasovagal Syncope Children: A Pilot Study.

Objective: To investigate if the low sodium intake is associated with the plasma carnitine and acylcarnitine profile in children with vasovagal syncope (VVS).Materials and Methods: Twenty-six children suffering from VVS were recruited in the present study and divided into a group of low urinary sodium excretion or a group of normal urinary sodium excretion according to the excretion of 24-h urinary sodium <3 or 3–6 g, respectively. The excretion of 24-h urinary sodium was detected with ion-selective electrode approach. Plasma carnitine and acylcarnitine concentrations were measured with tandem mass spectrometry. Each participant completed the head-up tilt test. The demographics, clinical characteristics, hemodynamic parameters and plasma carnitine and acylcarnitine concentrations were compared between the two groups. A bivariate correlation between plasma acylcarnitine profiles and the excretion of 24-h urinary sodium was conducted with Spearman's correlation coefficients.Results: Of the enrolled VVS patients, 14 patients were assigned to the group of low urinary sodium excretion and the remaining 12 patients were assigned to the group of normal urinary sodium excretion. Symptoms of fatigue were more prevalent in the group of low urinary sodium excretion than in the group of normal urinary sodium excretion (p = 0.009). Aside from fatigue, no other differences in the demographics, clinical characteristics or hemodynamic parameters during the head-up tilt test were found between the two groups (p > 0.05). Concentrations of plasma tiglylcarnitine (C5:1), hydroxyhexadecanoylcarnitine (C16OH), hydroxyoctadecanoylcarnitine (C18OH), and carnitine C22 were significantly higher in the group of low urinary sodium excretion than in the group of normal urinary sodium excretion (all p-values = 0.048); moreover, they were all negatively correlated with 24-h urinary sodium levels (all p-values = 0.016). There were no differences between the two groups in other acylcarnitines or free carnitine.Conclusions: Reduced excretion of 24-h urinary sodium is associated with a disturbed plasma acylcarnitine profile in children with VVS. The findings suggest that restricted sodium intake-induced disturbance of plasma acylcarnitines and related cellular energy metabolism might be involved in the pathogenesis of VVS in children.

Duration of treatment with oral rehydration salts for vasovagal syncope in children and adolescents.

Oral rehydration salt (ORS) is a first-line medication for vasovagal syncope (VVS) in children and adolescents. We retrospectively investigated the treatment with ORS-I (Na 90 mmol/L) for VVS in children and adolescents to define appropriate duration of treatment. All patients with a diagnosis of VVS, based on the first head-up tilt test (HUTT) response, and who accepted ORS-I treatment were enrolled. ORS was stopped when the HUTT response turned negative. Patients were followed for six months after cessation of ORS treatment. The study group included 129 patients (57 male, 72 female; mean age, 11.8 ± 2.0 years, age range, 7.0- 17.0 years). Median duration of VVS was 4 months (range, 1 week to > 10 years). The number of syncope ranged from 2 times to > 20 times. Mean follow-up time was 27.8 ± 6.9 weeks (range, 26-33 weeks). It took to 2~13 weeks for HUTT response to turn negative, with an average time of 8.4 weeks (95% confidence interval, 6.89~9.84 weeks). There was no statistical difference for the time to negative HUTT response according to age groups ( < 12-year-old vs. ≥12-year-old), syncope type (vasodepressor vs. mixed), and the syncope frequency. No patient experienced syncope after cessation of ORS treatment. Our findings suggest that ORS-I is an effective measure to treat children and adolescents with VVS. We recommend a treatment course of 2 months.

Changes in heart rate deceleration capacity and variability in resting children with vasovagal syncope

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. Key words: Vasovagal syncope; Deceleration capacity; Heart rate variability; Autonomic nervous function

Twenty-four-hour urine NE level as a predictor of the therapeutic response to metoprolol in children with recurrent vasovagal syncope.

Vasovagal syncope (VVS) is a heterogeneous disorder that creates challenges for treatment. Metoprolol is an important therapeutic option for children with VVS. The study examined the predictive value of 24-h urine norepinephrine (NE) levels in the assessment of the therapeutic efficacy of metoprolol for recurrent VVS in children. Thirty-eight children with recurrent VVS and 20 healthy children were enrolled in our study. Twenty-four-hour urine NE levels were measured by LC-MS-MS. VVS children were diagnosed by BHUTT and/or SNHUTT, and received metoprolol treatment for 3months. Symptom scoring was utilized to evaluate the therapeutic effect. A ROC curve was used to investigate the predictive value of 24-h urine norepinephrine levels. There exists significant correlation between 24-h urine NE levels and supine systolic and diastolic blood pressures. The 24-h urine NE levels of responders (40.75 ± 12.86μg/24h) were higher than those of nonresponders (21.48 ± 6.49μg/24h), and there was a significant difference between the two groups (P < 0.001). A ROC curve of the predictive value of 24h urine NE levels revealed that the area under the curve was 0.926. A cutoff value for 24-h urine NE level of 34.84μg/24h produced both high sensitivity (70%) and specificity (100%) in predicting the efficacy of metoprolol therapy for VVS. Patients with high 24-h urine NE levels have higher supine systolic and diastolic pressures and more effective responses to metoprolol. A 24-h urine norepinephrine level of > 34.84μg/24h was an indicator of the effectiveness of metoprolol therapy for VVS in children.

Gut microbiota analysis and its significance in vasovagal syncope in children.

Background:Vasovagal syncope (VVS) is common in children and greatly affect both physical and mental health. But the mechanisms have not been completely explained. This study was designed to analyze the gut microbiota in children with VVS and explore its clinical significance.Methods:Fecal samples from 20 VVS children and 20 matched controls were collected, and the microbiota were analyzed by 16S rRNA gene sequencing. The diversity and microbiota compositions of the VVS cases and controls were compared with the independent sample t test or Mann-Whitney U test. The correlation between the predominant bacteria and clinical symptoms was analyzed using Pearson or Spearman correlation test.Results:No significant differences in diversity were evident between VVS and controls (P > 0.05). At the family level, the relative abundance of Ruminococcaceae was significantly higher in VVS children than in controls (median [Q1, Q3]: 22.10% [16.89%, 27.36%] vs. 13.92% [10.31%, 20.18%], Z = −2.40, P < 0.05), and LEfSe analysis revealed Ruminococcaceae as a discriminative feature (linear discriminant analysis [LDA] score > 4, P < 0.05). The relative abundance of Ruminococcaceae in VVS patients was positively correlated with the frequency of syncope (r = 0.616, P < 0.01). In terms of its correlation with hemodynamics, we showed that relative abundance of Ruminococcaceae was negatively correlated with the systolic and diastolic pressure reduction at the positive response in head-up tilt test (HUTT; r = −0.489 and −0.448, all P < 0.05), but was positively correlated with the mean pressure drop and decline rate (r = 0.489 and 0.467, all P < 0.05) as well as diastolic pressure drop and decline rate at the HUTT positive response (r = 0.579 and 0.589, all P < 0.01) in VVS patients.Conclusion:Ruminococcaceae was the predominant gut bacteria and was associated with the clinical symptoms and hemodynamics of VVS, suggesting that gut microbiota might be involved in the development of VVS.