Objective:To investigate the relationship between body mass index (BMI) and response time of cardioinhibitory type vasovagal syncope (VVS-CI) in children.Methods:The clinical data of 56 children with syncope or pre-syncope were retrospectively analyzed and they visited specialist clinic for syncope and were diagnosed as VVS-CI in the Second Xiangya Hospital, Central South University from December 2012 to September 2019.Based on height and weight, BMI was calculated, and divided into low BMI group (35 cases) and normal BMI group (21 cases). Between the 2 groups, baseline heart rate, head-up tilt test (HUTT) positive response heart rate, baseline head-up tilt test (BHUT) positive response time, and sublingual nitroglycerin-provocated HUTT (SNHUT) positive response time were compared.The correlation between BMI and positive response time was analyzed.SPSS 22.0 software was applied for statistical analysis.Results:There were no significant differences in age, sex, duration of disease and number of syncope between the 2 groups (all P>0.05). No significant differences were found in baseline heart rate and positive response heart rate between the 2 groups [(78.5±15.3) times/min vs.(72.8±8.7) times/min, t=1.223, P=0.230; (44.0±13.9) times/min vs.(47.0±10.0) times/min, t=-0.664, P=0.511]. Compared with normal BMI group, BHUT positive patients/SNHUT positive patients were higher in low BMI group (27/8 cases vs.9/12 cases, χ2=4.839, P=0.027), and the positive response time of BHUT was shorter [(13.1±4.6) min vs.(23.7±9.5) min, t=-2.691, P=0.023]. There were no significant differences in SNHUT positive response time between the 2 groups ( P>0.05). Low BMI was correlated with BHUT positive response time ( r=0.750, P=0.005). Normal BMI was not associated with BHUT positive response time ( r=0.316, P=0.217). There was no correlation between low BMI and normal BMI and SNHUT positive response time ( r=0.177, P=0.431; r=0.021, P=0.940). Conclusions:Low BMI is positively correlated with BHUT positive response time of children with VVS-CI.The time it takes for syncope occurrence was shorter in children with low BMI than that in normal BMI.

Objective:To investigate the circadian rhythm of blood pressure and morning blood pressure surge (MBPS) in children with neurally mediated syncope (NMS).Methods:From July 2018 to June 2019, 135 cases [aged 3-16 years old (10.12±2.53) years old, with 74 males and 61 females] with unexplained syncope, presyncope, and symptoms such as headache, dizziness, chest pain, and chest tightness were collected in the Second Xiangya Hospital, Central South University for the first time.The 24 hour ambulatory blood pressure monitoring (24 h ABPM) was completed on the same day of the head-up tilt test (HUTT). Patients were divided into HUTT negative and positive groups, and dippers and non-dippers groups. MBPS (sleep-trough surge) was calculated and compared respectively.Results:(1) There were 51 patients in the HUTT positive group, including 27 patients with vasovagal syncope, 23 patients with postural orthostatic tachycardia syndrome, and 1 patient with orthostatic hypotension. In HUTT positive group, there were 22 cases (43.14%) of dippers and 29 cases of non-dippers.There were 84 patients in the HUTT negative group, there were 32 cases (38.10%) of dippers and 52 cases of non-dippers. There were no statistical significances in the dipper proportion between HUTT positive and negative group ( χ2=1.305, P>0.05). (2) Sleep-trough systolic blood pressure (SBP) surge was 1-45 mmHg [(15.97±8.03) mmHg](1 mmHg=0.133 kPa), and sleep-trough diastolic blood pressure (DBP) surge was -6-43 mmHg[(14.05±7.97) mmHg]. There were no statistical significances in sleep-trough surge between the HUTT negative and positive group (all P>0.05). (3) The age in the dipper group was higher than that in the non-dipper group [(10.72±2.20) years old vs. (9.72±2.66) years old, t=2.288, P<0.05]. The daytime average SBP [(110.20±8.33) mmHg vs.(105.54±7.51) mmHg, t=3.381, P<0.01], and morning peak SBP [(109.99±10.19) mmHg vs.(106.63±8.71) mmHg, t=2.045, P<0.05] of the dipper group were higher than those of the non-dipper group.The nighttime average SBP[(95.41±7.50) mmHg vs.(98.59±6.88) mmHg, t=2.540, P<0.01], nighttime average DBP[(48.61±4.52) mmHg vs.(52.28±4.65) mmHg, t=4.547, P<0.01], nocturnal minimum SBP[(89.62±8.18) mmHg vs.(93.60±7.38) mmHg, t=2.940, P<0.01], and nocturnal minimum DBP[(44.99±5.32) mmHg vs.(49.01±5.54) mmHg, t=4.205, P<0.01] of the dipper group were lower than that of the non-dipper group.Nocturnal SBP reduction rate [(13.42±2.68)% vs.(6.48±2.49)%, t=15.384, P<0.01], nocturnal DBP reduction rate[(19.98±4.92)% vs.(12.46±5.05)%, t=8.561, P<0.01], sleep-trough SBP surge[(20.37±8.30) mmHg vs.(13.03±6.36) mmHg, t=5.800, P<0.01], and sleep-trough DBP surge[(16.91±8.06) mmHg vs.(12.13±7.36) mmHg, t=3.554, P<0.01] of the dipper group were higher than those of the non-dipper group. Conclusions:Nocturnal blood pressure reduction and sleep-trough surge decreased in NMS children, and there is a circadian rhythm disorder of blood pressure.

Objective:To analyze the association between the types of response to head-up tilt test (HUTT) and levels of various vitamins in children and adolescents with orthostatic intolerance.Methods:Sixty-five cases of children and adolescents 35 males and 30 females aged 5-14 (10.5±2.0) years old who complained orthostatic intolerance symptoms, including syncope, dizziness, headache, and chest tightness, in Children′s Medical Center, the Se-cond Xiangya Hospital, Central South University between November 2018 and April 2019, were enrolled.By comprehensive history, physical examination, and necessary laboratory testing, heart, cerebrovascular and other system diseases were excluded.According to HUTT result, these patients were divided into 2 groups, namely negative HUTT group and positive HUTT group.The serum levels of vitamin A 1, B 1, B 2, B 6, B 9, B 12, C, and E were compared between the 2 groups.Continuous data were analyzed by conducting t-test and categorical data were analyzed by performing χ2 test. Results:(1) There were 32 cases (18 males and 14 females) in negative HUTT group and 33 cases (17 males and 16 females) in positive HUTT groups, with 28 cases of vaso vagal syncope and 5 cases of postural tachycardia syndrome.There were no significant differences in age, gender ratio, and body mass index between the negative HUTT group and positive HUTT group.(2) The serum level of vitamin B 1 of positive HUTT group was lower than that of negative HUTT group [(77.43±16.70) nmol/L vs.(88.56±18.98) nmol/L, t=-2.513, P<0.05], while the levels of vitamin A 1, B 2, B 6, B 9, B 12, C, and E had no significant differences between the two groups (all P>0.05). Conclusions:Patients with positive responses to HUTT relatively lacked vitamin B 1, suggesting the role of vitamin B 1 in the pathophysiological process of neurally mediated syncope.

Objective:To discuss the relationship between heart rate (HR) and heart rate differences (HRD) at different time points in head-up tilt test (HUTT) and the occurrence of postural tachycardia syndrome(POTS) in children and adolescents.Methods:A total of 217 children and adolescents diagnosed as POTS, who complained of syncope or presyncope, were chosen as POTS group (aged 6 to 16 years). During the same period, 73 healthy children and adolescents with matching gender and age were selected as control group.All subjects underwent HUTT from October 2000 to November 2019.Get HR (HR0, HR5, HR10) in baseline, HUTT 5 min and 10 min, HRD (HRD5, HRD10) of HR in HUTT 5 min and 10 min minus HR in baseline.Results:(1) HR5, HR10, HRD5, and HRD10 were higher in the POTS group than those in the control group( P<0.05). (2) Univariate Logistic regression: There was a correlation between HR5, HR10, HRD5, HRD10 and the risk of POTS( P<0.01). (3) Multivariable Logistic regression: For each additional unit of HRD5 and HRD10, the risk of POTS increased by 27% ( OR=1.27, 95% CI1.16 to 1.36) and 28% ( OR=1.28, 95% CI1.20 to 1.38). Conclusion:HR and HRD are related with the occurrence of POTS in children and adolescents, but HR and HRD at different time points of HUTT play the little role on the effect size of the occurrence of POTS.

Objective:To study the diagnostic efficacy and prognostic evaluation value of QT interval dispersion (QTd) in children and adolescents with cardioinhibitory vasovagal syncope (VVS-CI).Methods:From July 2010 to January 2020, 80 children and adolescents who received their first visit or admission to the Pediatric Syncope Clinic of The Second Xiangya Hospital of Central South University and definite diagnosed of VVS-CI due to syncope or presyncope were selected as the VVS-CI group, meanwhile, 80 children and adolescents who had physical examination in the hospital were selected as the control group.QT interval were measured by 12-lead electrocardiogram at the baseline.Results:(1) Comparison between the two groups: Compared with the control group, the VVS-CI group had a significantly lower heart rate ( P<0.05) and significantly longer QT interval, such as the maximum QT interval (QTmax), minimum QT interval (QTmin), QTd, corrected maximum QT interval (QTcmax) and corrected QT interval dispersion (QTcd) ( P<0.05). After follow-up 84 (45, 127) days, compared with the responsive group, the non-responsive group had a significantly longer QT interval, such as QTmax, QTd, QTcmax, corrected minimum QT interval (QTcmin)and QTcd ( P<0.05). (2) Diagnostic efficiency: QTmax, QTmin, QTd, QTcmax and QTcd had a certain diagnostic value in children and adolescents with VVS-CI ( P<0.001). QTd had the largest area under the curve (AUC) (0.914), and had a sensitivity of 86.30% and a specificity of 84.95% at the optimal cut-off value of 28.50 ms for VVS-CI diagnosis.(3) Prognostic evaluation value: QTmax, QTd, QTcmax, QTcmin, QTcd had an estimated value for the prognosis of VVS-CI in children and adolescents ( P<0.05 or 0.01). QTd had the largest AUC (0.906) and the best cut-off value was 34.50 ms, the sensitivity to predict response to VVS-CI intervention was 90.00%, and the specificity was 82.35%. Conclusion:QTd of electrocardiogram has a good estimation value in the diagnosis and prognosis of VVS-CI in children and adolescents.

Objective:To investigate the difference of heart rate variability in cardioinhibitory type vasovagal syncope(VVS-CI) children with different body mass index(BMI).Methods:Clinical data of thirty-four children with syncope or pre-syncope were retrospectively analyzed, who visited specialist clinic for syncope and diagnosed as VVS-CI at the Second Xiangya Hospital of Central South University from January 2012 to December 2019.BMI was calculated based on height and weight, and divided into lean group(BMI≤18.4 kg/m 2, n=19) and normal group(BMI 18.5-23.9 kg/m 2, n=15). Heart rate variability(HRV) of 24 h dynamic electrocardiogram was analyzed using linear analysis method.Time domain index included SDNN, SDANN, rMSSD and pNN50.Frequency domain index included total power(TP), ultra low frequency power(ULF), very low frequency power(VLF), low frequency power(LF), high frequency power(HF) and LF/HF. Results:There was no significant difference in SDNN, SDANN and rMSSD between lean and normal group( P>0.05), but pNN50 increased in lean group( P<0.05). No significant differences were found in TP, ULF, LF, HF and LF/HF between two groups( P>0.05), while VLF was lower in lean group than that in normal group( P<0.05). There was no statistical difference in time domain index and frequency domain index between different gender between lean and normal group( P>0.05). SDNN, SDANN and LF were higher in<12 years old than those in≥12 years old in lean group( P<0.05). There was no statistical difference in rMSSD, pNN50, TP, ULF, VLF, HF and LF/HF( P>0.05). ULF increased and LF decreased in<12 years old compared to ≥12 years old in normal group( P<0.05). No statistical differences were found in SDNN, SDANN, rMSSD, pNN50, TP, VLF, HF and LF/HF( P>0.05). Conclusion:The autonomic nervous regulation function of VVS-CI children with low BMI and normal BMI is different, resulting in HRV difference.There were also differences in HRV between<12 years old and ≥12 years old with the same BMI.

Objective:To investigate the value of rate-pressure product (RPP) in predicating the prognosis of postural tachycardia syndrome (POTS) in children.Methods:Fifty-three children (26 males and 27 females) aged 5 to 15 who had syncope of unknown reasons or presyncope and were diagnosed with POTS by head-up tilt test (HUTT) at the Children′s Syncope Specialist Clinic, the Second Xiangya Hospital, Central South University from April 2012 to May 2019 were selected as the POTS group.Thirty-eight children aged 5 to 16 (19 males and 19 females) who underwent medical examinations at the Children′s Health Specialist Clinic of the Second Xiangya Hospital, Central South University over the same period were enrolled as controls (control group). POTS children were followed up after intervention and they were divided into the response group ( n=40) and the non-response group ( n=13) according to the follow-up results.The products (RPP0, RPP5, RPP10) of the heart rate (HR0, HR5, HR10) and systolic blood pressure (SBP0, SBP5, SBP10) at baseline (HUTT 0 min), HUTT 5 min and HUTT 10 min were calculated.Statistical analysis was performed using SPSS 22.0 software and EmpowerStats software. Results:(1) There was no statistical difference in age and gender between the POTS group and the control group (all P> 0.05). (2) HR5 [(115.45±14.50) times/min vs.(95.79±13.89) times/min], HR10 [(120.57±16.13) times/min vs.(96.05±12.43) times/min], RPP5 (12 814.55±2 304.56 vs.10 371.42±1 910.20), and RPP10 (13 449.17±2 360.40 vs.10 523.18±1 771.48) in the POTS group were significantly higher than those in the control group( t=0.799, 7.842, 5.747, 6.446, all P<0.01). No statistical difference of HR0 and RPP0 was observed between the 2 groups (all P>0.05). (3) In the POTS group: HR5 [(98.73±12.43) times/min vs.(113.77±17.65) times/min], HR10 [(96.90±13.96) times/min vs.(119.08±13.52) times/min], RPP5 (11 125.45±1 952.35 vs.12 914.69±3 192.12) and RPP10 (10 819.58± 2 144.26 vs.13 375.46±2 807.01) in the response group were significantly lower than those in the non-response group( t=3.406, 5.012, 2.432, 3.455, all P<0.01). HR0 and RPP0 were no significantly different between the 2 groups(all P>0.05). (4) When SBP10<114 mmHg(1 mmHg= 0.133 kPa), the probability of response after POTS intervention increased by 10% with every 1 mmHg increase in SBP10, and there was a non-linear relationship between the 2 group ( P<0.05). (5) The receiver operating characteristic curve suggested that when RPP5 was 11 548.50, the sensitivity and specificity to predict the response after POTS intervention were 81.82% and 61.70%, respectively.When RPP10 was 10 988.00, the sensitivity and specificity were 77.78% and 86.21%, respectively. Conclusions:RPP is closely related to the intervention effect of POTS in children.RPP5 and RPP10 can predict the prognosis of POTS in children.There is a non-linear relationship between SBP10 and the intervention effect of POTS in children.

Objective To discuss the relationship between body mass index(BMI)and flag_raising syncope ( PS)and micturition syncope(MS)in children and adolescents. Methods One hundred and six children and adoles_cents with PS or MS diagnosed at the Department of Dediatric Cardiovasology,Childrenˊs Medical Center,the Second Xiangya Hospital,Central South University from January 2003 to September 2017 were studied,including 51 males and 55 females,and their ages ranged from 5 to 18 years. There were 63 cases in the PS group(21 males and 42 females) and 43 cases in the MS group(30 males and 13 females). One hundred healthy children and adolescents including 50 males and 50 females who had routine healthy examinations at the hospital in the same period were selected as control subjects(healthy control group). Body length and body mass were measured,and BMI was calculated. Statistical inves_tigations were conducted with SDSS 22. 0 software. Results (1)The body mass and BMI in the PS group were lower than those in the MS group[(36. 33 ± 9. 85)kg vs.(42. 85 ± 12. 44)kg;(16. 56 ± 2. 41)kg∕m2 vs.(18. 48 ± 3. 04) kg∕m2],and the differences were statistically significant(F﹦7. 529,12. 411,all P〈0. 05). There was no difference in body length among the PS group,the MS group and the healthy control group[(146. 62 ± 12. 89)cm vs.(150. 79 ± 12. 78)cm vs.( 149. 75 ± 16. 02 )cm,F ﹦1. 314,P 〉0. 05 ]. No differences were found in age,frequency,body length,body mass and BMI between the PS syncope group and the MS group with different genders(all P〉0. 05).(2) The number of BMI_underweight children increased in the PS group(82. 53%,52∕63 cases)compared with that of the MS group(58. 14%,25∕43 cases)and that of the healthy control group( 52. 00%,52∕100 cases),and the difference was statistically significant(χ2 ﹦14. 556,P〈0. 01).(3)The positive rate by head_up tilt test(HUTT)was 72. 64%(77∕104 cases),and HUTT of the PS group was higher than that of the MS group[82. 53%(52∕63 cases)vs. 58. 14%(25∕43 cases)],and there was a significant difference statistically(χ2 ﹦7. 656,P〈0. 01). Conclusions Low BMI is prone to PS in children and adolescents.

Objective To retrospectively analyze the etiological distribution and clinical features of autonomic neuromediated syncope ( NMS) in children and adolescents in single center for 15 years. Methods There were 3182 cases of children and adolescents[aged from 2 to 18 years,the average age(10. 75 ± 3. 13) years] with unexplained syncope or symptoms of presyncope ( including unexplained dizziness,headache,chest tightness,chest pain,sigh,heart palpitations,etc),who came from children syncope outpatient department or inpatient department in the Second Xiangya Hospital,Central South University from September 2000 to October 2015. Of all 3182 cases,1649 cases were male,1533 cases were female. All subjects underwent detailed history collection,careful physical examination,12-lead electrocardiogram,Holter ECG,chest X-ray,echocardiography, EEG and head CT or MRI,blood biochemical examination (including fasting glucose,myocardial enzymes) and were eliminated organic disease of heart,lung,brain and so on,the cause of syncope was not still clear. The head-up tilt test ( HUTT ) was performed after the patient or / and the guardian written informed consent obtained. Results (1)HUTT positive rate was 47. 05％ (1497/3182). Causes for vasovagal syncope in turn was 42. 99％ ( 1368/3182 ) , postural orthostatic tachycardia syndrome was 2. 55％ ( 81/3182 ) , orthostatic hypertension was 0. 79％ (25/3182),orthostatic hypotension was 0. 06％ (2/3182). (2)The clinical symp-toms in NMS of different etiologies were mainly syncope,dizziness,chest tightness,chest pain,headache,heart pal-pitations. Conclusion The causes of NMS in children are vasovagal syncope and postural orthostatic tachycardia syndrome,and the clinical features are syncope,dizziness,chest tightness,chest pain,headache,heart palpitations.

Objective To investigate the changes of amplitude of T wave and ST segment between the supine and orthostatic electrocardiogram in children and adolescents with postural tachycardia syndrome (POTS). Methods A total of 74 children and adolescents diagnosed as POTS by head-up tilt test (HUTT),who complained of unexplained dizziness,headache,syncope or other symptoms,were chosen as POTS group. A total of 64 children and adolescents who did the health check in our child health clinic were selected as control group by age and sex in the same period. All the cases in this study came from the syncope specialized clinic or inpatient department of the Second Xiangya Hospital,Central South University,from August 2013 to January 2016. The heart rate and the 12-lead T-wave and ST-segment amplitude of the supine and orthostatic electrocardiogram were measured by software and manual intervention. Results (1) Com-pared with supine electrocardiogram,the heart rate of orthostatic electrocardiogram of POTS group increased [(105. 2 ± 16. 3) times/ min vs. (83. 8 ± 18. 0) times/ min,t = - 7. 598,P < 0. 01],the T-wave amplitude decreased in lead Ⅰ[(0. 28 ± 0. 14) mV vs. (0. 33 ± 0. 11) mV,t = 2. 598,P < 0. 05],Ⅱ[(0. 28 ± 0. 12) mV vs. (0. 39 ± 0. 13) mV,t = 5. 340,P < 0. 01],Ⅲ[(0. 00 ± 0. 19) mV vs. (0. 07 ± 0. 11) mV,t = 3. 041, P < 0. 01],aVF[(0. 14 ± 0. 13) mV vs. (0. 23 ± 0. 11) mV,t = 4. 505,P < 0. 01],V4 [(0. 33 ± 0. 21) mV vs. (0. 51 ± 0. 23) mV,t = 4. 938,P < 0. 01],V5 [(0. 37 ± 0. 10) mV vs. (0. 50 ± 0. 15) mV,t = 7. 764,P <0. 01] and V6 [(0. 25 ± 0. 10) mV vs. (0. 37 ± 0. 10) mV,t = 7. 538,P < 0. 01],the T-wave amplitude in-creased in lead aVR[( - 0. 27 ± 0. 11) mV vs. ( - 0. 36 ± 0. 10) mV,t = - 5. 023,P < 0. 01],and the ST-segment amplitude increased in lead V 5 [(0. 07 ± 0. 04) mV vs. (0. 06 ± 0. 04) mV,t = - 2. 309,P < 0. 05]. (2) Compared with control group,the difference of heart rate of POTS group increased [( - 21. 4 ± 14. 0) times/ min vs. ( - 10. 7 ± 11. 4)times/ min,t = 4. 875,P < 0. 01],and the difference of T-wave amplitude in-creased in lead Ⅰ[(0. 05 ± 0. 10) mV vs. ( - 0. 01 ± 0. 15) mV,t = - 3. 161,P < 0. 01],Ⅱ[(0. 11 ± 0. 12) mV vs. (0. 07 ± 0. 12) mV,t = - 2. 243,P < 0. 05],V4 [(0. 18 ± 0. 18) mV vs. (0. 07 ± 0. 20) mV,t =- 3. 282,P < 0. 01],V5 [(0. 18 ± 0. 11) mV vs. (0. 14 ± 0. 13) mV,t = - 2. 013,P < 0. 05] and V6 [(0. 13 ± 0. 08) mV vs. (0. 08 ± 0. 10) mV,t = - 3. 364,P < 0. 01],and the difference of T-wave amplitude in-creased significant in lead aVR[( - 0. 09 ± 0. 08) mV vs. ( - 0. 03 ± 0. 08) mV,t = 4. 109,P < 0. 01]. (3) Logistic regression analysis:the difference of heart rate and T-wave amplitude in lead V5 and V6 on supine and orthostatic electrocardiogram was statistically valuable for the diagnosis of POTS (P < 0. 05). (4) Diag-nostic test evaluation:when the difference of heart rate ≥15 times/ min,of T-wave amplitude in lead V5 and lead V 6≥ 0. 10 mV separately,on supine and orthostatic electrocardiogram at the same time,the sensitivity of the diagnosis of POTS was 37. 8％ and the specificity was 81. 3％ . (5)The follow-up of children and adoles-cents with POTS showed no significant difference of T-wave amplitude and ST-segment amplitude on ortho-static and supine ECG comparing to the initial diagnosis,regardless of the type of HUTT reaction remained or turned negative (P >0. 05). Conclusion The difference of heart rate and of T-wave amplitude in lead V5 and V6 are valuable for the diagnosis of POTS in children and adolescents.