Postural dysautonomia in response to head-up tilt in a military pilot aspirant: Aeromedical considerations

Intolerance to orthostasis encompasses a group of responses on assumption of upright posture. One such response is postural dysautonomia. One of the types of postural dysautonomia is postural orthostatic tachycardia syndrome, which is characterised by an increase in heart rate of more than 30 bpm without hypotension along with other features of dysautonomia on attaining an erect posture, either actively or passively. This paper brings out a case of postural dysautonomia in a pilot aspirant in response to Head-up tilt (HUT) test. A 23-year-old female military pilot aspirant reported for evaluation of Syncope and Air Sickness. She gave a history of solitary episode of loss of consciousness on ground while preparing for an early morning sortie. She was diagnosed with a case of neurocardiogenic syncope and was put back to flying training. Subsequently, after about 2 months, she developed features of air sickness while flying and also could not tolerate preliminary motion sickness desensitisation at her unit. A thorough medical evaluation failed to reveal any neurocardiological abnormality. Before commencing the air sickness desensitisation protocol at the Institute of Aerospace Medicine, she was subjected to HUT during which she developed signs and symptoms suggestive of postural dysautonomia. A test retest assessment with repeat HUT and passive standing test revealed similar responses.

Pediatric patients head-up-tilt-test with pharmacological challenge, it is safe? / Mesa inclinada en pacientes pediátricos con reto farmacológico, ¿es seguro?

Abstract Syncope in pediatrics represents an important cause of visits to the emergency units. For this reason, excluding a cardiac or malignant origin is essential at the time of the initial approach to determine what is the next step in management, or if they need to be referred to a pediatric cardiologist and/or electrophysiologist. Vasovagal syncope is the most frequent cause of syncope in pediatrics, in which a detailed clinical history is enough to make the diagnosis. If no diagnosis is concluded by the history, or if it is necessary to define the hemodynamic response of the patients, the head-up-tilt-test is indicated; this will trigger syncope due to an orthostatic stress caused by the angulated table (passive phase). If a negative response remains, it can be followed by a pharmacologic challenge to trigger the hemodynamic response, which is still controversial in pediatrics. The pharmacologic challenge increases the sensitivity with a slight reduction in test specificity. Although there is not a specific drug for the challenge in pediatric patients yet, the most commonly drugs used are nitrates and isoproterenol, the latter related to a great number of adverse effects. Sublingual administration of nitrates in the challenge has been proven to be ideal, effective, and safe in this specific age group. The aim of this article is to make a literature search to demonstrate the effectiveness and safety of the pharmacologic challenge during the head-up-tilt-test in pediatrics, emphasizing a study conducted at the National Institute of Cardiology with isosorbide dinitrate.

Resumen El síncope en edades pediátricas representa una causa importante en las visitas a unidades de urgencias, por lo que excluir un origen cardíaco o maligno es fundamental al momento del abordaje inicial para determinar la conducta a seguir o la necesidad de derivar al cardiólogo pediatra o electrofisiólogo. El síncope vasovagal (SVV) es la causa más frecuente de síncope en pediatría, para cuyo diagnóstico basta una historia clínica detallada. Cuando ésta no es suficiente para determinar el diagnóstico de síncope reflejo o es necesario definir el tipo de respuesta que lo origina, está indicada una prueba de mesa inclinada que produce un estrés ortostático por la angulación y ello desencadena un síncope (fase pasiva). En pruebas no concluyentes está indicado un reto farmacológico para precipitar la respuesta hemodinámica, pero aún es un tema de controversia en edades pediátricas. El reto farmacológico incrementa la sensibilidad de la prueba, con una ligera reducción de la especificidad. Si bien no existe todavía un medicamento específico para la población pediátrica, los más empleados son los nitratos y el isoproterenol, este último relacionado con un mayor número de efectos adversos. La administración sublingual de los nitratos utilizados ha demostrado ser ideal, efectiva y segura en los pacientes pediátricos. El objetivo del artículo es realizar una revisión de las publicaciones médicas que demuestran la efectividad y seguridad del reto farmacológico durante la prueba de mesa inclinada en pacientes pediátricos, con énfasis en un estudio conducido en el Instituto Nacional de Cardiología con dinitrato de isosorbida (DNIS).

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.

Changes in ventricular late potentials in children and adolescents with postural tachycardia syndrome / 中华实用儿科临床杂志

Objective@#To investigate the changes in ventricular late potentials (VLP) in children and adolescents with postural tachycardia syndrome (POTS).@*Methods@#One hundred and forty-four children and adolescents diagnosed as POTS by using the head-up tilt test (HUTT) in Second Xiangya Hospital of Central South University from January 2012 to March 2019 were selected as POTS group, their age ranged 4 to 16 years old[(11.03±2.34)years old], there were 65 boys and 79 girls.Ninety-one healthy children and adolescents matched by age and gender[aged 4-16 (11.22±1.68) years old, there were 50 boys and 41 girls]were selected as the healthy control group.VLP was measured by SR-1000A ECG automatic analyzer (Boai, Guangdong, China).@*Results@#Compared with the healthy control group, the prevalence of positive VLP in the POTS group increased [ 11.1%(16/144 cases)vs.1.1%(1/91cases)], and the difference was statistically significant(χ2= 6.904, P<0.01); the heart rate in the POTS group increased compared with that in the healthy control group[82.0 (74.0-95.0) times/min vs.78.0 (71.0-86.0) times/min], and the difference was statistically significant(Z=-2.265, P<0.05); the low-amplitude signal(LAS40) in the POTS group prolonged compared with that in the healthy control group[23.0 (17.0-31.0) μV vs.19.0 (13.0-25.0) μV], and the difference was statistically significant(Z=-4.114, P<0.01); root mean square amplitude(RMS40) increased compared with that in the healthy control group[61.3 (34.4-79.1) ms vs.52.0 (38.8-64.5) ms], and the difference was statistically significant (Z=-2.469, P<0.05). There was no statistically significant difference in total QRS time (TQRS) between 2 groups [86.0 (76.0-97.5) ms vs.87.0 (81.0-94.0) ms, Z=-0.007, P>0.05].@*Conclusions@#The positive rate of VLP is increased of children and adolescents with POTS.It suggests that there is an abnormal cardiac electrical activity in children and adolescents with POTS.

Changes in ventricular late potentials in children and adolescents with postural tachycardia syndrome / 中华实用儿科临床杂志

Objective To investigate the changes in ventricular late potentials (VLP) in children and adolescents with postural tachycardia syndrome (POTS).Methods One hundred and forty-four children and adolescents diagnosed as POTS by using the head-up tilt test (HUTT) in Second Xiangya Hospital of Central South University from January 2012 to March 2019 were selected as POTS group,their age ranged 4 to 16 years old [(11.03 ± 2.34) years old],there were 65 boys and 79 girls.Ninety-one healthy children and adolescents matched by age and gender [aged 4-16 (11.22 ± 1.68) years old,there were 50 boys and 41 girls] were selected as the healthy control group.VLP was measured by SR-1000A ECG automatic analyzer (Boai,Guangdong,China).Results Compared with the healthy control group,the prevalence of positive VLP in the POTS group increased [11.1％ (16/144 cases)vs.1.1％ (1/91 cases)],and the difference was statistically significant(x2=6.904,P ＜ 0.01);the heart rate in the POTS group increased compared with that in the healthy control group [82.0 (74.0-95.0) times/min vs.78.0 (71.0-86.0) times/min],and the difference was statistically significant (Z =-2.265,P ＜ 0.05);the low-amplitude signal (LAS40) in the POTS group prolonged compared with that in the healthy control group[23.0 (17.0-31.0) μV vs.19.0 (13.0-25.0) μV],and the difference was statistically significant (Z =-4.114,P ＜ 0.01);root mean square amplitude(RMS40) increased compared with that in the healthy control group [61.3 (34.4-79.1) ms vs.52.0 (38.8-64.5) ms],and the difference was statistically significant (Z =-2.469,P ＜ 0.05).There was no statistically significant difference in total QRS time (TQRS) between 2 groups [86.0 (76.0-97.5) ms vs.87.0 (81.0-94.0) ms,Z =-0.007,P ＞ 0.05].Conclusions The positive rate of VLP is increased of children and adolescents with POTS.It suggests that there is an abnormal cardiac electrical activity in children and adolescents with POTS.

The etiological distribution and clinical features of autonomic neuromediated syncope in children and adolescents:single center 15 years retrospective analysis / 中国小儿急救医学

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.

Etiology and prognosis of children and adolescents with situational syncope / 中华实用儿科临床杂志

Objective To retrospectively analyze the etiology and prognosis of the children and adolescents with situational syncope in a single center.Methods There were 4 274 cases of children and adolescents [aged from 2 to 18 years old,the average age being (10.82 ± 3.13)years old],male 2 208 cases,female 2 066 cases with ortho-static intolerance syndromes,such as unexplained syncope or symptoms of presyncope,etc,who were treated at Children's Syncope Outpatient Department or Inpatient Department in the Second Xiangya Hospital,Central South University from January 2000 to November 2017.All subjects underwent detailed history investigation,careful physical examinations, routine 12-lead electrocardiogram,Holter electrocardiogram(ECG),chest X-ray,echocardiography,electroencephalo-gram(EEG)and head computerized tomography(CT)or magnetic resonance imaging(MRI),blood biochemical exami-nation (including fasting glucose,myocardial enzymes)and organic diseases in the heart,brain,blood vessels were ex-cluded,but the cause of syncope was still not clear.The head-up tilt table test (HUTT)was performed after the pa-tients or/and the families wrote the informed consent agreement.Results A total of 177 (4.14%)patients with situa-tional syncope were diagnosed among 4 274 cases.Etiology included the abdominal musecle exercise (35.59%,63/177 cases),urination (24.29%,43/177 cases),bathing (9.60%,17/177 cases),defecation (7.34%,13/177 cases), singing (5. 08%,9/177 cases),rides (4.52%,8/177 cases),blood-injection-injury phobia (3.95%,7/177 ca-ses),swallowing (3.39%,6/177 cases),and hair-grooming (2. 82%,5/177 cases),syncope during acupuncture treatment (2. 26%,4/177 cases),and cough (1.13%,2/177 cases). The common positions were upright position (84.18%,149/177 cases),squatting to standing position (8.47%,15/177 cases),sitting position (5.08%,9/177 cases),and squatting position (2.26%,4/177 cases).HUTT positive rate was 69.49%(123/177 cases),common type of hemodynamic were the vasodepressive type of vasovagal syncope (45.20%,80/177 cases),mixed type of vaso-vagal syncope (19.77%,35/177 cases),postural orthostatic tachycardia syndrome (3.39%,6/177 cases)and the cardiac suppressive type of vasovagal syncope (1.13%,2/177 cases).In 35 cases of situational syncope,the number of children and adolescents with syncope was significantly reduced by health education and upstanding training.By the first follow-up review,the cases were reduced from (2.69 ± 1.81)times to (0.59 ± 0.96)times after healthy edu-cation of 2-16 weeks [(4.97 ± 3.16)weeks].By the second follow-up review,3 out of 8 cases did not faint,3 cases fainted 1 time,1 case fainted 2 times,and 1 case fainted 4 times.The outcomes of the first reexamination of HUTT in 16 cases were negative,and other 3 cases were negative by twice visit.Conclusions The etiology of children and adoles-cents are flag-raising(abdominal muscle exercise),urination,bathing,defecation,singing,riding,blood-injection-injury phobia,swallowing,hair -grooming,syncope during acupuncture treatment and coughing. Healthy education is good for situational syncope.

Comparison of curative effect and serum electrolytes between different oral rehydration salts in treatment of neurally mediated syncope children / 中南大学学报(医学版)

Objective:To compare the curative effect and the changes of serum electrolytes between oral rehydration salts (ORS) Ⅰ and ORS Ⅲ treatment in neurally mediated syncope children.Methods:The children with the symptom of unexplained syncope and pre-syncope were collected in Second Xiangya Hospital from May 2014 to May 2017.After head-up tilt test (HUTT),their serum electrolytes levels were examined.Children who were positive in the HUTT received ORS (ORS Ⅰ or ORS Ⅲ) and health education.Subjects were randomly divided into an ORS Ⅰ group (n=27) and an ORS Ⅲ group (n=49).Results:There was no statistical significance in sex,age,height,body mass,initial diagnosis and re-diagnosis interval between the 2 groups (P＞0.05);the total efficiency after ORS Ⅲ and ORS Ⅰ treatment were 79.59％ and 62.96％,respectively,with no statistical significance (x2=2.483,P＞0.05);the HUTT negative conversion rate after ORS Ⅲ and ORS Ⅰ treatment were 51.02％ and 48.16％,respectively,with no statistical significance (x2=0.058,P＞0.05);before treatment,the serum sodium [(140.20±2.26) mmol/L vs (138.39±2.72) mmol/L;t=2.856,P＜0.05] in the ORS Ⅲ group was higher than that in the ORS Ⅰ group,the serum phosphorus [(1.46±0.19) mmol/L vs (1.65±0.29) mmol/L;t=3.146,P＜0.05] in the ORS Ⅲ group was lower than that in the ORS Ⅰ group;after treatment,the serum sodium [(140.31±2.01) mmol/L vs (138.88±2.08) mmol/L;t=2.692,P＜0.05] and serum calcium [(2.31±0.09) mmol/L vs (2.24±0.11) mmol/L;t=2.696,P＜0.05] in the ORS Ⅲ group were higher than those in the ORS Ⅰ group,the serum phosphorus [(1.45±0.16) mmol/L vs (1.61±0.25) mmol/L;t=3.128,P＜0.05] in the ORS Ⅲ group was lower than that in the ORS Ⅰ group;after ORS Ⅲ treatment,there was no statistical significance in serum electrolytes between HUTT positive group and HUTT negative group (P＞0.05);after ORS Ⅰ treatment,the serum calcium [(2.29±0.10) mmol/L vs (2.19±0.10) mmol/L;t=2.501,P＜0.05]and serum phosphorus [(1.71±0.24) mmol/L vs (1.50±0.21) mmol/L;t=2.392,P＜0.05] in HUTT positive group were higher than those in HUTT negative group.There was no statistical significance in serum sodium,potassium,magnesium,and chloride (P＞0.05);there was no statistical significance in serum electrolytes between pre-treatment and post-treatment in the ORS Ⅰ group and the ORS Ⅲ group (P＞0.05);there was no statistical significance in serum electrolytes between vasovagal syncope and postural orthostatic tachycardia syndrome in the ORS Ⅰ group and the ORS Ⅲ group before ORS treatment (P＞0.05).Conclusion:The ORS Ⅲ and ORS Ⅰ have the similar efficacy in the treatment of children with neurally mediated syncope.ORS Ⅲ is easier to be accepted by children than ORS Ⅰ,with better compliance.

Relationship between unexplained palpitation in children and head-up tilt test / 中南大学学报(医学版)

Objective:To explore the relationship between unexplained palpitation in children and head-up tilt test (HUTT).Methods:A total of 142 children with the main symptom of unexplained palpitation were admitted to the Specialist Out-Patient Clinic of Children's Cardiovascular Disease from Sept.2008 to Feb.2017 in the Second Xiangya Hospital,Central South University.Among them,63 cases were male,79 cases were female,with the mean age of (10.12±2.88) years old.The detailed history,physical examinations,conventional 12 electrocardiogram,chest X-ray,echocardiography,myocardial enzymes and thyroid function were all examined.The disorders of heart disease,systemic disease and drug effect were ruled out.The HUTT inspection was then given to them.Results:Among the 142 palpitation cases,79 cases were HUTT positive (55.6％) and 63 cases were HUTT negative (44.4％).The age in HUTT positive patients was older than that in HUTT negative patients (P＜0.05),with no significant difference in gender (P＞0.05).There were three types of hemodynamic changes in HUTT positive patients.Among them,38 cases were postural orthostatic tachycardia syndrome (48.1％),36 cases were the vasovagal syncope vasodepressive type (45.6％) and 5 cases were the vasovagal syncope mixed type (6.3％).There were no hemodynamic types for vasovagal syncope cardioinhibitory type,orthostatic hypotension and orthostatic hypertension.Conclusion:Among the clinically unexplained palpitations children,more than half are caused by unbalanced autonomic nervous function.HUTT can help clear the cause of unexplained palpitations.

Several questions of head-up tilt test in the Children with neurally mediated syncope / 国际儿科学杂志

Neurally mediated syncope (NMS)is common in pediatric emergency and intensive care unit.Head-up tilt test(HUTT)has been widely used as an valuable diagnostic tools for NMS,while the results would be affected by multiple factors.Controversies still exist on issues such as the influence factors of positive rate,complication and clinical predictions of the HUTT.In this review,several problems in the application of HUTT in NMS of children are reviewed.

The predictive value of orthostatic intolerance symptoms in children and adolescents to the head-up tilt test results / 中国小儿急救医学

Objective To explore the predictive value of orthostatic intolerance( OI) symptoms in children and adolescents to the head-up tilt test( HUTT) results. Methods A total of 274 children or adoles-cents complaining with the following symptoms were chosen:unexplained syncope,dizziness,headache,chest tightness,chest pain,sigh,and so on. The 274 cases included 141 males and 133 females aging from 5 to 18 years old with a mean age of (11. 8 ± 2. 7) years. All the cases in this study came from the syncope special-ized clinic or inpatient department of the Second Xiangya Hospital,Central South University,from July 2016 to March 2017. All the patients had been asked in detail about the history, physical examination, routine 12-lead electrocardiogram,chest X-ray,echocardiogram,electroencephalogram,head computer tomography or magnetic resonance imaging,blood and a series of checks to exclude organic heart,brain,lung diseases. Each patient was asked to finish OI questionnaire and HUTT. Results All 274 patients were divided into HUTT negative group(n=151) and HUTT positive group(n=123). Dizziness(65. 3％) was the most common OI symptom,followed by syncope(50. 7％),blurred vision or amaurosis(45. 6％) and fatigue(43. 4％). There were significant differences in the prevalence of palpitation,headache,profuse perspiration,blurred vision or amaurosis,chest tightness,dizziness,gastrointestinal symptoms( nausea,vomiting,abdominal pain,abdominal distension) and syncope between HUTT positive and HUTT negative groups ( P<0. 05 ) . According to the multivariate Logistic regression analysis,these eight OI symptoms could affect the results of HUTT to some extent(odds ratio>1). Conclusion The symptoms of palpitation,headache,profuse perspiration,blurred vi-sion,chest discomfort,dizziness,gastrointestinal symptoms( nausea,vomiting,abdominal pain,abdominal dis-tension) and syncope can impact the positive results of HUTT.

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.

Electrocardiogram Characteristics of Suspected Vasovagal Syncope Patients With Positive Head-Up Tilt Test / 中国循环杂志

Objective: To investigate the dynamic electrocardiogram (ECG) changes of head-up tilt test in patients with suspected vasovagal syncope. Methods: A total of 502 outpatients of our hospital with suspicious vasovagal syncope from 2015-08 to 2016-12 were enrolled. All patients received head-up tilt test with synchronization of 12 lead ECG. Based on head-up tilt test result, the patients were divided into 2 groups: Positive group,n=244 and Negative group,n=258. The P wave duration, corrective QT (QTc) duration and P wave axis in ECG were compared between 2 groups. Results: Compared with Negative group, Positive group had the longer P wave duration (95.65±38.50) ms vs (88.61±17.09) ms,P<0.05; P wave axis was right shifted before syncope (69.87±18.18)° vs (66.82±16.51)° , while left shifted during syncope (62.87±25.39)° vs (68.47±15.30)° and after syncope (56.87±22.45)° vs (68.49±16.35)°, allP<0.05; the shorter QTc duration before syncope (418.69±92.35) ms vs (435.76±59.29) ms,P<0.05. Conclusion: The patients with vasovagal syncope had some speciifc ECG features during head-up tilt test including P wave duration, P wave axis and QTc duration, those may play certain forewarning function for vasovagal syncope onset.

Head-up tilt test induced shortened QT interval:a case report and literature review / 临床儿科杂志

Objective To explore the cause of secondary QT interval shortening. Method The data of a child with vasovagal syncope and cardiac depression in whom shortened QT interval was induced in head-up tilt test (HUTT) was analyzed retrospectively, and the related literatures were reviewed. Result A 12-year-old boy visited for fainting when brushing his teeth in the morning. ECG showed sinus bradycardia, heart rate at 55 times /min and normal QT and QTc interval. Dynamic electrocardiogram showed sinus rhythm, mean heart rate at 70 times/min, atrial anterior contraction 3 times, normal mean QT and mean QTc. UCG showed approximately normal heart structure and the left ventricular systolic function. There was no abnormality in EEG and cranial CT. His fasting blood glucose was 5.2 mmol/L. The basal tilt test was positive with vasovagal syncope and cardiac depression. During the tilt table test, Holter monitoring showed that sinus arrest occurred in the child when upright tilt for16 min, and then fainted. Time of sinus arrest was 2.9 s and 11.4 s, respectively, and artificial chest compressions were performed. The QT interval was shortened (QT=330 ms), and so was QTc interval (QTc=320 ms). The ratio of QT/QTp was 78% (the lower limit of normal QT interval was 88% of QTp) before sinus arrest occurred. Conclusion Increased vagal tone may induce QT interval shortening.

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.

Effect of 15°-head up tilt position on quality of respiratory system during anesthesia recovery period in obese patients / 临床麻醉学杂志

Objective To observe the effect of 15°-head up tilt position on quality of respiratory system during anesthesia recovery period in obese patients.Methods Eighty obese patients in ASA physical status Ⅰ or Ⅱ,aged 18-60 years,with BMI≥28 kg/m2,scheduled for elective otological surgery with microscopy,were randomly divided into 2 equal groups (n =40 each):the 15°-head up tilt position group (group H) and the supine position group (group C).With traditional induction,an esthesia was maintained by TCI of propofol 2-4 μg/ml and remifentanil 5-6ug/ml,not supplying muscle relaxant during operation.After operation,group H was in 15°-head up tilt position,while group C in supine position.The time spans from recovery of spontaneous breathing to meeting the extubation standard (X) and to meeting the standard for discharging form PACU (Y) were recorded.After extubation,we also recorded the time for SpO2decreased from 100％ to 92％ with fresh air (Z) and for SpO2 increased from 92％ to 100％ with pure oxygen (W).PaO2,PaCO2 and pH were monitored before oxygen inhalation,after 3 min of oxygen inhalation,at the end of surgery,before extubation and before discharging from PACU.Results Compared with group C [(19±6) min,(57±10) min,(51 ±9) s],the time of X (14±7) min,Y (45±7) min and W (39±11) s,was significantly shorter and the time of W was obviously longer in group H(P＜0.05).Compared with group C [(169.1± 29.4) mm Hg,(70.8±4.1) mm Hg],the PaO2was increased obviously before extubation and discharging from PACU in group H [(193.4±30.5) mm Hg,(82.2±3.4) mm Hg](P＜0.05).There was no significantly difference in PaO2 at other time points.There was no significantly difference in PaCO2and pH at all points.Conclusion 15°-head up tilt position during anesthesia recovery period in obese patients can effectively improve the quality of respiratory system.

Cardiovascular coupling during graded postural challenge: comparison between linear tools and joint symbolic analysis

ABSTRACT Background A joint symbolic analysis (JSA) is applied to assess the strength of the cardiovascular coupling from spontaneous beat-to-beat variability of the heart period (HP) and the systolic arterial pressure (SAP) during an experimental protocol inducing a gradual baroreflex unloading evoked by postural change (i.e. graded head-up tilt). Method: The adopted JSA can quantify the degree of association between the HP and SAP variabilities as a function of the time scale of the HP and SAP patterns. Traditional linear tools assessing the HP-SAP coupling strength, such as squared correlation coefficient, squared coherence function, and percentage of baroreflex sequences, were computed as well for comparison. Results: We found that: i) JSA indicated that the strength of the cardiovascular coupling at slow temporal scales gradually increased with the magnitude of the orthostatic challenge, while that at fast temporal scales gradually decreased; ii) the squared correlation coefficient and percentage of baroreflex sequences did not detect this behavior; iii) even though squared coherence function could measure the magnitude of the HP-SAP coupling as a function of the time scale, it was less powerful than JSA owing to the larger dispersion of the frequency domain indexes. Conclusion: Due to its peculiar features and high statistical power, JSA deserves applications to pathological groups in which the link between HP and SAP variabilities is lost or decreased due to the overall depression or impairment of the cardiovascular control.

Value of head-up tilt table test in the diagnosis of syncope in children / 中华实用儿科临床杂志

Syncope is a common emergency condition,which can cause harmful danger to the physical and mental health,quality of living and learning of children.Even,syncope -related body traumatic injuries and anxiety and depression often occur in these children,and some have a high risk of sudden death.So,early diagnosis is of great sig-nificance.Head -up tilt table test is considered the gold standard for the diagnosis of syncope,it plays a significant role in diagnosis,differential diagnosis,treatment and evaluation of therapeutic effects.