BACKGROUND: Functional syncope and vasovagal syncope (VVS) in children both present with transient loss of consciousness (TLOC) and are clinically challenging to differentiate. This study aims to delineate the distinguishing features among factors associated with TLOC induction in these two conditions. METHODS: A total of 31 children presenting with syncope and diagnosed as functional syncope were enrolled in the functional syncope group; concurrently, 40 children presenting with syncope and diagnosed with VVS were enrolled in the VVS group. Clinical manifestations— including demographic characteristics, precipitating factors, prodromal symptoms, syncope episode characteristics, family history, and psychosocial stressors—were systematically compared between the two groups. RESULTS: Body weight was significantly higher in the functional syncope group than in the VVS group (P < 0.05). No statistically significant differences were observed between the groups in terms of sex distribution, age, body height, or baseline resting heart rate (P > 0.05). Compared with the VVS group, the functional syncope group exhibited significantly fewer identifiable triggers, fewer presyncope symptoms, and a lower prevalence of familial syncope history (all P < 0.05). Conversely, the functional syncope group demonstrated significantly longer syncope duration, higher syncope frequency, and greater exposure to emotional stress events (all P < 0.05). Disease duration did not differ significantly between the two groups (P > 0.05). CONCLUSIONS: Children with functional syncope exhibit distinct clinical profiles relative to those with VVS, characterized by fewer precipitating factors and prodromal symptoms, longer duration and higher frequency of syncope episodes, reduced familial syncope history, and increased association with emotional stress events.

Objectives: Clinically feasible simple methods for prognostic assessment of cardioinhibitory vasovagal syncope (VVS) are rare. This study investigated the predictive utility of head-up tile test (HUTT) data among cardioinhibitory VVS children with non-pharmacological therapy. Methods: A retrospective analysis was conducted on the clinical data of 403 children with VVS who had cardioinhibitory responses induced by HUTT. The children were aged 4-18 years old, including 178 males and 225 females. After the non-pharmacological interventions and follow-up, they were divided into the good prognosis group (233 cases) and the poor prognosis group (170 cases). Results: (1) Comparison between groups: Compared with the good prognosis group, the baseline heart rate (HR0) in the poor prognosis group was lower, and the proportion of sublingual nitroglycerin-provoked HUTT (SNHUT) was higher (p < 0.05). (2) Univariate analysis: Univariate analysis showed that HR0 was a protective factor on the prognosis of VVS, while SNHUT was a risk factor for the prognosis of VVS. (3) Multivariate analysis: HR0 was an independent protective factor on the prognosis of VVS. That is, for every 1 bpm increase in HR0, the risk of poor prognosis of VVS decreased by 3%. SNHUT was an independent risk factor for the prognosis of VVS, and the risk of poor prognosis of VVS increased by 3.34 times compared with basic HUTT (BHUT). (4) Evaluation of diagnostic tests: The combination of HR0 and HUTT mode had a good prognostic prediction effect for VVS (AUC = 0.71, p < 0.001). Conclusions: The combination of HR0 and HUTT mode demonstrates robust prognostic predictive value for non-pharmacological interventions in pediatric patients with VVS exhibiting cardioinhibitory responses during HUTT.

INTRODUCTION:The ryanodine receptor 2 gene mutation associated with catecholaminergic polymorphic ventricular tachycardia is one of the aetiologies of cardiac syncope and has the risk of sudden cardiac death. This study reported two novel ryanodine receptor 2 gene variants. CASE DESCRIPTION:We described two 9-year-old girls with recurrent syncope during exercise or stress presenting two novel ryanodine receptor 2 gene variants (c.6938T>G/p. Val2313Gly and c.12263A>C/p. His4088Pro) associated with catecholaminergic polymorphic ventricular tachycardia through a comprehensive review of medical history, examination findings and genetic testing. Propranolol was used for treatment, and the two patients didn't experience episodes of syncope during follow-up for 6 months. Besides, literature associated with catecholaminergic polymorphic ventricular tachycardia and ryanodine receptor 2 mutations was reviewed. CONCLUSIONS:Recurrent syncope during exertion or stress should be focused on catecholaminergic polymorphic ventricular tachycardia caused by ryanodine receptor 2 gene mutations. The genetic testing is a crucial tool in confirming the mutation of catecholaminergic polymorphic ventricular tachycardia. Early recognition of this disease, timely diagnosis of ryanodine receptor 2 gene mutations, and administration of appropriate pharmacological agents or ICD implantation are critical to ensure favourable clinical outcomes.

Pediatric postural orthostatic tachycardia syndrome is one of the main haemodynamic types of neurally mediated syncope and is commonly seen in school-aged children. Heart rate and blood pressure are important physiological indicators in the human cardiovascular system. They are easily accessible in clinical practice and have the advantages of being non-invasive, simple and safe. This article will review the predictive value of heart rate and blood pressure in the diagnosis and prognosis of pediatric postural orthostatic tachycardia syndrome.

Objective: To investigate the changes in T-wave amplitude and Tp-Te interval on supine and standing electrocardiograms (ECGs) in pediatric postural orthostatic tachycardia syndrome (POTS), and to explore their predictive value for the therapeutic effect of metoprolol. Methods: A total of 59 children diagnosed with POTS who presented with syncope or pre-syncopal symptoms were enrolled as the POTS group, and 52 healthy children served as the control group. Supine and standing ECGs were recorded for all subjects, and T-wave amplitude and Tp-Te interval were measured. Children with POTS were followed-up after metoprolol treatment and divided into a therapeutic response group and a non-response group. Results: (1) Comparison of supine vs. standing ECGs: In the POTS group, standing posture (compared with supine posture) was associated with increased heart rate (HR), decreased T-wave amplitude in leads II, III, aVF, V4, V5, and V6, shortened Tp-Te interval in leads I, II, III, aVR, aVF, V1, V3, V4, V5, and V6, and elevated Tp-Te/QT ratio in leads aVL and V5 (all p < 0.05). (2) Comparison with the control group: The POTS group exhibited a greater HR difference (ΔHR), as well as larger differences in T-wave amplitude (ΔT-wave amplitude) between supine and standing positions in leads II, aVR, aVL, aVF, V3, and V5 (all p < 0.05). (3) Follow-up: Compared with the non-response group, the therapeutic response group showed larger ΔT-wave amplitude in leads III, aVF, V2, V3, V4, and V5, larger Tp-Te interval difference (ΔTp-Te interval) in lead V3, and larger Tp-Te/QT ratio difference (ΔTp-Te/QT ratio) in lead V3 (all p < 0.05). (4) Receiver operating characteristic curve: ΔT-wave amplitude in leads III, aVF, V2, V3, V4, and V5, ΔTp-Te interval in lead V3, and ΔTp-Te/QT ratio in lead V3 all had predictive value for the therapeutic effect of metoprolol in pediatric POTS (all p < 0.05). Conclusions: ΔHR and ΔT-wave amplitude in lead V5 between supine and standing positions are independent risk factors for pediatric POTS. A combination of five indicators-ΔT-wave amplitude in leads V2, V3, and V5, ΔTp-Te interval in lead V3, and ΔTp-Te/QT ratio in lead V3 between supine and standing ECGs-exerts a good predictive effect on the therapeutic response of pediatric POTS to metoprolol intervention.

BACKGROUND:Malignant vasovagal syncope (VVS) is characterized by cardiac arrest lasting more than 3 seconds during a syncope episode or head-up tilt test (HUTT). We aim to conduct a risk assessment for potential malignant VVS before the HUTT by using economic, simple and convenient demographic data, in order to prevent adverse outcomes for pediatric VVS. PURPOSE:To explore the correlation between demographic factors and pediatric malignant VVS, and verify the value of these factors in early risk assessment for malignant VVS before HUTT, so as to optimize test safety and reduce adverse events. METHODS:We conducted a retrospective analysis of the clinical data of 3,734 children who were initially diagnosed with VVS due to unexplained syncope and presyncope. Finally, 122 children who met the diagnostic criteria for malignant VVS were included in the malignant VVS group, and 661 children who did not meet the criteria during the same period were matched as the control group. By analyzing demographic data and other factors, we attempted to clarify the association between these factors and malignant VVS. RESULTS:Linear relationship: age and body mass index (BMI) have independent protective effects on malignant VVS. For every 1-year increase in age and every 1 kg/m2 increase in BMI, the risk of malignant VVS decreases by 12% and 9%, respectively. Nonlinear relationship: When the age is <12.9 years old, for every additional year of age, the risk of malignant VVS decreases by 20%. For ages 12.9 years and above, the efficacy is not significant. There is no significant nonlinear relationship between BMI and malignant VVS. CONCLUSION:Age and BMI are independent protective factors for pediatric malignant VVS. Before the age of 12.9 years, the incidence of malignant VVS gradually decreases with the increase in age, and thereafter there is no significant impact.

This research aimed to investigate the value of clinical data in preterm infants on admission for the early prediction of retinopathy of prematurity (ROP). 98 preterm infants (66 males and 32 females) with an average gestational age of 30.42 ± 1.20 weeks were included. Basic vital signs, clinical tests, and maternal information were collected at admission. Preterm infants were divided into a non-ROP group and a ROP group based on whether they eventually developed ROP. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the above indexes and the combined indexes in the ROP of preterm infants. (1) The differences in systolic blood pressure (SBP), red blood cell count (RBC), hemoglobin (HGB), direct bilirubin (DBIL), and total bilirubin (TBIL) were statistically significant between the non-ROP group and ROP group (all P < 0.05). (2) RBC, HGB, DBIL, and TBIL, all of which have diagnostic value for ROP [area under curve (AUC) 0.643, 0644, 0.887, and 0.744, respectively, all P < 0.05]. (3) The combined indicator possessed a good diagnostic value for ROP (AUC of 0.962, P < 0.05), with a sensitivity and specificity of 88.64% and 91.49%, respectively. (4) Combined indicator (body temperature, body weight, heart rate, SBP, diastolic blood pressure, mean arterial pressure, RBC, HGB, red blood cell distribution width, DBIL, TBIL) has better diagnostic value for ROP than each of RBC, HGB, DBIL, and TBIL alone (Z-value 5.386, 5.475, 2.410 and 4.420, respectively, all P < 0.05). Combined indicator has good predictive value for ROP in preterm infants.

To explore the impact of school periods and long holiday periods on the occurrence of neurally mediated syncope (NMS) in children. A retrospective analysis was conducted on 262 children with NMS. The children were aged 4–17 years, 119 males. 244 cases were diagnosed as vasovagal syncope, and 18 cases as postural orthostatic tachycardia syndrome. The data on the age, sex, syncope triggers, hemodynamic types, family history of syncope of children with syncope during long holiday periods group (n = 68) and school periods group (n = 194) were compared. (1) Incidence of syncope: The incidence of syncope during school periods (74.05

To investigate the correlation between prognostic nutritional index (PNI) and vasovagal syncope (VVS) in children, as well as its predictive value. 151 children (68 males, aged 4–18 years) diagnosed with VVS due to unexplained syncope and presyncope in our hospital from January 2022 to December 2023 were the study group, 152 healthy children (72 males, aged 7–14 years) who underwent physical examination in the same hospital during the same period of time were matched as the control group. Serum albumin (SA), serum globulin (SG), albumin/globulin (AGR), and peripheral blood lymphocyte absolute count (Lc) were measured, and PNI was calculated. ①PNI (51.35 vs. 55.28), SA (40.90 g/L vs. 43.05 g/L), AGR (1.65 vs. 1.75), and Lc (2.08 × 109/L vs. 2.49 × 109/L) were decreased in VVS group compared with control group (P < 0.05). ②Predictive analysis of VVS by PNI: The area under receiver operator characteristic curve of PNI prediction of VVS was 0.814, which indicated that PNI had moderate predictive value for VVS diagnosis. When PNI cutoff value was 55.00, the sensitivity, specificity, and Youden index of predicting VVS were 90.73

BACKGROUND:Both psychogenic pseudosyncope (PPS) and vasovagal syncope (VVS) in children and adolescents are diseases of transient loss of consciousness. It is difficult to distinguish them clinically. This paper will study the differential diagnostic value of P wave dispersion (Pd) and QT interval dispersion (QTd) between PPS and VVS. METHODS:The 31 children with PPS and 40 children with VVS from July 2014 to November 2023 were enrolled as the study group. Meanwhile, 30 healthy children who underwent a physical examination at the same hospital were matched to the control group. P wave duration and QT interval in the 12-lead electrocardiogram were measured at the baseline. RESULTS:(1) Comparison between groups: ① The Pd, corrected P wave dispersion (Pcd), QTd, and corrected QT interval dispersion (QTcd) in PPS group were significantly higher than those in control group (P < 0.05). The minimum P wave duration (Pmin) and corrected P wave duration (Pcmin) in PPS group were significantly lower than those in control group (P < 0.05). There were no significant differences in maximum P wave duration (Pmax), corrected maximum P-wave duration (Pcmax), maximum QT interval (QTmax), minimum QT interval (QTmin), corrected maximum QT interval (QTcmax), and corrected minimum QT interval (QTcmin) between PPS group and control group (P > 0.05). ② The Pd, Pcd, QTd, and QTcd in VVS group were significantly higher than those in control group (P < 0.05). The Pmin, Pcmin, and QTcmin in VVS group were significantly lower than those in control group (P < 0.05). There were no significant differences in Pmax, Pcmax, QTmax, QTmin, and QTcmax between VVS group and control group (P > 0.05). ③ The Pmax, Pd, QTmax, QTd, and QTcd in PPS group were significantly lower than those in VVS group (P < 0.05). There were no significant differences in Pmin, Pcmax, Pcmin, Pcd, QTmin, QTcmax, and QTcmin between PPS group and VVS group (P > 0.05). (2) ROC curve: Pmax, Pd, QTmax, QTd, and QTcd had a certain differential diagnostic value between PPS and VVS in children and adolescents (P < 0.05). QTd had the largest area under curve (0.735), with a sensitivity of 85.00% and a specificity of 53.30% at the cut off value of ≥ 28.11 ms for VVS diagnosis. CONCLUSIONS:In children and adolescents, electrocardiogram parameters such as Pmax, Pd, QTmax, QTd, and QTcd all possess predictive value in differentiating between PPS and VVS. Among them, QTd has the greatest differential diagnostic value.

Situational syncope refers to syncope that occurs in specific situations and is a special type of neurally mediated syncope. The etiologic composition of situational syncope varies between adults and children. In adults, it is more common during micturition and defecation, whereas in children, it is more frequently seen during flag-raising, micturition, and defecation. The clinical features and underlying mechanisms of various types of situational syncope also differ in terms of age and sex. The treatment of situational syncope mainly includes nonpharmacologic treatment, pharmacologic treatment, and surgical treatment. Adverse events related to situational syncope are rare, and the prognosis is generally good if there are no other systemic diseases. However, in patients with underlying cardiovascular diseases, situational syncope can lead to serious cardiovascular adverse events.

BACKGROUND:Headache and dizziness are common symptoms in children and adolescents, but the causes of headache/dizziness in most pediatric patients are not clearly defined. We intended to investigate the demographic and clinical features of pediatric patients with headache and/or dizziness and responses to head-up tilt test (HUTT). METHODS:The demographic data and medical records of children and adolescents, with a primary complaint of headache and/or dizziness and undergoing HUTT between January 2001 and June 2023, were retrospectively reviewed and analyzed. Children and adolescents with headache and/or dizziness secondary to fever, trauma, or other obvious etiology were excluded. For those with positive responses to HUTT, the symptom score and HUTT responses were collected after treatment at follow-up. RESULTS:Among 2709 patients with unexplained headache and/or dizziness, 1080 (39.87%) cases presented positive responses to HUTT, whereas 1629 (60.13%) cases had negative responses. Among patients with positive responses, 930 (34.33%) cases presented a response of vasovagal syncope, 143 (5.28%) cases of postural orthostatic tachycardia syndrome, and 7 (0.26%) cases of orthostatic hypertension. Multivariate Logistic regression analysis demonstrated that females, older age, and low body mass index percentile increased the risk of being positive responses. At follow-up, HUTT results of 236 patients were collected, among which 131 (55.51%) cases turned negative HUTT responses and had headache/dizziness symptoms improved after treatment targeted autonomic dysfunction. CONCLUSION:HUTT can be applied to evaluate the autonomic function of children and adolescents with headache and/or dizziness and assess the treatment responses in those patients with autonomic dysfunction.

Psychogenic pseudosyncope is one of the primary causes of transient loss of consciousness in children and adolescents, essentially classified as a conversion disorder that significantly impacts patients' quality of life. Clinically, psychogenic pseudosyncope shares certain similarities with vasovagal syncope in terms of pre-syncope symptoms and triggers, making it sometimes difficult to differentiate and easily misdiagnosed. Therefore, placing emphasis upon the characteristics of psychogenic pseudosyncope is crucial for early identification and treatment, which holds significant importance for the mental and psychological health of children and adolescents. In the present review, we aimed to address psychogenic pseudosyncope with clinical features, diagnosis, and treatment.

Vasovagal syncope (VVS) is the most common cause of neurally mediated syncope in children. Recurrent syncope severely affects physical and mental health and may lead to unintentional injury. Based on international and domestic guidelines and clinical practice experience, standardized recommendations for the diagnosis and treatment of pediatric VVS are proposed. Management of VVS should be individualized, and non-pharmacological interventions, including lifestyle modifications, are the cornerstone for both classic and malignant VVS. Pharmacological therapy is recommended for children with VVS who have recurrent syncopal episodes, are at risk of trauma, or respond poorly to non-pharmacological interventions. For children in whom the head-up tilt test induces asystole, pacemaker implantation is not recommended as first-line therapy. In malignant VVS with recurrent syncope despite conventional treatment, pacemaker implantation may be considered after specialist evaluation. Data on cardioneuroablation in children are limited, and long-term follow-up is required.

OBJECTIVE:To evaluate the prognostic value of electrocardiographic ventricular repolarisation parameters in children with dilated cardiomyopathy. METHODS:A retrospective study was conducted involving 89 children with dilated cardiomyopathy [age 5.24 (4.32, 6.15) years] as the research group, and a control group consisting of 80 healthy children matched for age and sex. Within the research group, there were 76 cases in the survival subgroup and 13 cases in the death subgroup. Ventricular repolarisation parameters were measured. RESULTS:(1) Compared to the control group, both QTcmax and QTcmin were significantly prolonged in the research group (P < 0.01). Additionally, Tp-Te /QT ratios for leads III, aVL, V1, V2, and V3 showed an increase (P < 0.05), while T-wave amplitudes for leads I, II, aVL, aVF, V4, V5, and V6 exhibited a decrease (P < 0.05). (2) In comparison to the survival subgroup, the diameters of the LV, RV, LA, and RA in the death subgroup were enlarged, while the left ventricular ejection fraction and eft ventricular fractional shortening were decreased (P < 0.05). The Tp-Te /QT ratios for leads aVR, V5, and V6 also increased notably (P < 0.05 or P < 0.01). The T-wave amplitude readings from leads II, aVF, and V6 demonstrated significant reductions (P < 0.05). CONCLUSION:Abnormal ventricular repolarisation parameters were found in dilated cardiomyopathy children. Increased Tp-Te /QT ratios in aVR, V5, and V6 leads and decreased T-wave amplitudes in II, aVF, and V6 leads were risk factors for predicting mortality in children with dilated cardiomyopathy.

The head-up tilt test (HUTT) is a fundamental tool for the clinical diagnosis of unexplained syncope. While HUTT has been extensively employed in adult populations for over three decades, its application in pediatric cases remains relatively limited. A comprehensive literature review was conducted to perform a multi-dimensional evaluation of HUTT in pediatric patients. This review focused on the differences in methodologies and diagnostic criteria for children versus adults, described diagnostic accuracy and safety of HUTT, and summarized risk factors of syncope events during the HUTT. Notable differences in HUTT between children and adults are evident across various parameters such as tilt angle, tilt duration, and the administration of pharmacological agents. In pediatric patients, HUTT not only helps in determining the subtype of orthostatic intolerance but also facilitates the identification of the etiology of unexplained symptoms such as syncope, sighing, palpitations, chest pain, and abdominal pain. Severe adverse events are uncommon; nevertheless, registered events include different types of arrhythmias or even cardiac arrest, temporary aphasia, convulsions, seizure-like activities, and psychological and psychiatric symptoms. Furthermore, the occurrence of syncope events during the HUTT is influenced by multiple factors including age, sex, height, weight, systolic blood pressure, diastolic blood pressure, hemodynamic type, average hemoglobin concentration levels of creatine kinase activity levels genetic predispositions, multivitamin status among others.

Background Metoprolol therapy for paediatric vasovagal syncope (VVS) has yielded inconsistent results, necessitating predictive markers. We aimed to develop and validate models to identify paediatric VVS patients likely to benefit from metoprolol. Methods 478 metoprolol-treated paediatric patients with VVS were enrolled from three syncope units and divided into retrospective training (March 2017-March 2023, n = 323) and prospective validation cohorts (April 2023-March 2024, n =155). Fourteen patients (2.9%) were excluded for lacking follow-up data. Patients were classified as responders or non-responders based on symptom improvement after 1-3 months of metoprolol therapy. Univariate analysis and logistic regression were used to select the candidate predictors. A nomogram and a scoring model were established to predict treatment efficacy. The model values were analysed using a receiver operating characteristic (ROC) curve. Consistency was evaluated using the Hosmer-Lemeshow (H-L) test, calibration curve, and concordance index (C-index). The clinical utility of model was assessed through the decision curve analysis (DCA). Internal validation was performed using the bootstrap approach. The predictive model derived from the training cohort was validated in the validation cohort to assess its accuracy and feasibility. Findings Increased heart rate during positive response in head-up tilt test (Delta HR), corrected QT interval dispersion (QTcd), and standard deviation of all normal-to-normal intervals (SDNN) were selected as independent predictors to develop a predictive model. A nomogram model was built (AUC: 0.900, 95% CI: 0.867-0.932); the H-L test and calibration curves showed a strong alignment between predicted and actual results. The scoring model was established in the training cohort (AUC: 0.941, 95% CI: 0.897-0.985), yielding a sensitivity of 82.8% and a specificity of 96.5%, with a cut-off value of 2.5 points. In the external validation cohort, the scoring model achieved a sensitivity, specificity, and accuracy of 93.6%, 80.9%, and 87.7%, respectively. Interpretation The nomogram and scoring model were constructed to predict the efficacy of metoprolol for children with VVS, which will greatly assist paediatricians in the individual management of VVS in children and adolescents. Copyright (c) 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Objective: Head-up tilt test (HUTT) is an important tool in the diagnosis of pediatric vasovagal syncope. This research will explore the relationship between syncopal symptoms and HUTT modes in pediatric vasovagal syncope. Methods: A retrospective analysis was performed on the clinical data of 2513 children aged 3-18 years, who were diagnosed with vasovagal syncope, from Jan. 2001 to Dec. 2021 due to unexplained syncope or pre-syncope. The average age was 11.76 +/- 2.83 years, including 1124 males and 1389 females. The patients were divided into the basic head-up tilt test (BHUT) group (596 patients) and the sublingual nitroglycerine head-up tilt test (SNHUT) group (1917 patients) according to the mode of positive HUTT at the time of confirmed pediatric vasovagal syncope. Results: (1) Baseline characteristics: Age, height, weight, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and composition ratio of syncope at baseline status were higher in the BHUT group than in the SNHUT group (all P < 0.05). (2) Univariate analysis: Age, height, weight, HR, SBP, DBP, and syncope were potential risk factors for BHUT positive (all P < 0.05). (3) Multivariate analysis: syncope was an independent risk factor for BHUT positive, with a probability increase of 121% compared to pre-syncope (P<0.001). Conclusion: The probability of BHUT positivity was significantly higher than SNHUT in pediatric vasovagal syncope with previous syncopal episodes.

Tpeak-Tend interval (Tp-Te) is an indicator of transmural dispersion of repolarization, which is often related to ventricular arrhythmias. The relationship between Tp-Te and vasovagal syncope (VVS) has been reported in previous studies, but very little is known about Tp-Te in differentiation between psychogenic pseudosyncope (PPS) and VVS in children. We aim to discuss the predictive value of Tp-Te of supine and orthostatic electrocardiogram (ECG) in the diagnosis between PPS and VVS in children. The 31 children with PPS and 40 children with VVS from July 2014 to November 2023 were enrolled as the study group. Meanwhile, 30 healthy children who underwent a physical examination in the same hospital were selected as the control group. Tp-Te and QT interval in 12-lead supine and orthostatic ECG were measured. (1) Supine ECG: ① The Tp-Te/QT in PPS group was significantly lower than that in control group in II lead (P < 0.05). The Tp-Te/QTc in PPS group was significantly lower than that in control group in II and aVR lead (P < 0.05). There was no significant difference in Tp-Te between PPS group and control group (P > 0.05). ② The Tp-Te in VVS group was significantly higher than that in control group in aVR, aVF, and V4 lead (P < 0.05). The Tp-Te/QT in VVS group was significantly higher than that in control group in aVF lead (P < 0.05). The Tp-Te/QTc in VVS group was significantly higher than that in control group in aVL, aVF and V1 lead (P < 0.05). ③ The Tp-Te, Tp-Te/QT in PPS group were significantly lower than those in VVS group in some leads (P < 0.05). The Tp-Te/QTc in PPS group was significantly lower than that in VVS group in some leads. (2) Orthostatic ECG: ① The Tp-Te in PPS group was significantly higher than that in control group in V1, V2 lead (P < 0.05). The Tp-Te/QT, Tp-Te/QTc in PPS group were significantly higher than those in control group in V2 lead (P < 0.05). ② The Tp-Te and Tp-Te/QTc in V4 lead, Tp-Te/QT in V1, V4 lead in VVS group were significantly higher than those in control group (P < 0.05). ③ The Tp-Te in PPS group was significantly lower than that in VVS group in some leads (P < 0.05). The Tp-Te/QT in PPS group was significantly lower than that in VVS group in some leads (P < 0.05). The Tp-Te/QTc in PPS group was significantly lower than that in VVS group in some leads. (3) The receiver-operating characteristic (ROC) curve analysis: Tp-Te of supine ECG and orthostatic ECG in some leads had a predictive value on diagnosis between PPS and VVS (P < 0.05). Tp-Te, Tp-Te/QT, and Tp-Te/QTc of supine and orthostatic ECG in some leads have a certain predictive value in the diagnosis between PPS and VVS in children.

This research proposed to retrospectively analyze 20 years of clinical data and investigate the relationship between demographic factors and syncopal symptom in pediatric vasovagal syncope. A total of 2513 children, 1124 males and 1389 females, age range 3–18 years, who presented to Department of Pediatric Cardiovasology, Children's Medical Center, The Second Xiangya Hospital, Central South University with unexplained syncope or pre-syncope and were diagnosed with vasovagal syncope were retrospectively collected and divided into syncope group (n = 1262) and pre-syncope group (n = 1251). (1) Females had a 36% increased risk of syncope compared to males, a 27% increased risk of syncope for every 1-year increase in age, and a 2% decreased risk of syncope for every 1 cm increase in height. (2) A non-linear relationship between age, height, weight and syncope was observed. When age > 10.67 years, the risk of syncope increases by 45% for each 1-year increase in age; when height < 146 cm, the risk of syncope decreases by 4% for each 1 cm increase in height; when weight < 28.5 kg, the risk of syncope decreases by 10% for each 1 kg increase in weight. Demographic factors are strongly associated with syncopal symptom in pediatric vasovagal syncope and can help to predict the risk.