Animals ; Neurotransmitter Agents ; metabolism ; Rabbits ; Syncope, Vasovagal ; metabolism ; physiopathology

Arrhythmias, Cardiac ; complications ; physiopathology ; Atrioventricular Block ; complications ; physiopathology ; Coronary Circulation ; Humans ; Male ; Middle Aged ; Syncope ; complications ; physiopathology

OBJECTIVETo study the clinical characteristics of orthostatic hypertension (OHT) in children.

METHODA total of 96 children with OHT who met the diagnostic criteria and clinical manifestations were recruited in the Department of Pediatrics, Peking University First Hospital. Age and sex distributions were observed. The duration of disease, the frequencies of symptoms and the predisposing factors were recorded. The hemodynamic changes from supine to up-right positions were also analyzed.

RESULTThere were 50 boys and 46 girls in the study group. The mean age was (11.8 ± 2.7) years. Thirty-two children were from 6 to 10 years old, accounting for 33.3% of all subjects, while 64 patients were from 11 to 17 years old, accounting for 66.7%. Durations of symptoms of OHT were less than 1 month in 22.9% children, from 1 month to 1 year in 51.1% children and longer than 1 year in 26.0% children. The most common clinical manifestations were syncope and dizziness. The incidence of them was 70.8% and 46.9%, respectively. Other clinical manifestations included transitional amaurosis, nausea and/or vomiting, pallor and so on. These clinical manifestations often occurred on position change (24.0%) and long-time standing (57.3%) in children. Other predisposing factors included exercise, emotion changes and fuggy environment. The baseline systolic and diastolic blood pressures were (103 ± 8) mm Hg (1 mm Hg = 0.133 kPa) and (59 ± 6) mm Hg, respectively, the up-right systolic and diastolic blood pressure at 3 min were (113 ± 8) mm Hg and (73 ± 6) mm Hg and the differences were significant (t = 27.674, P < 0.01; t = 17.936, P < 0.01). The baseline heart rate in supine position was (81 ± 11) bpm and the maximum heart rate in up-right position was (113 ± 12) bpm (t = 33.092, P < 0.01).

CONCLUSIONOHT is commonly seen in puberty of children. The chief complaints are syncope and dizziness. They were mostly induced by position change and long-time standing. Blood pressure was significantly increased from supine to up-right position.

Adolescent ; Blood Pressure ; physiology ; Child ; Dizziness ; epidemiology ; physiopathology ; Female ; Heart Rate ; Humans ; Hypotension, Orthostatic ; epidemiology ; etiology ; physiopathology ; Male ; Multivariate Analysis ; Posture ; Risk Factors ; Syncope ; epidemiology ; physiopathology

Blood Pressure ; Drugs, Chinese Herbal ; therapeutic use ; Humans ; Hypertension ; complications ; drug therapy ; physiopathology ; Hypotension, Orthostatic ; complications ; drug therapy ; physiopathology ; Male ; Middle Aged ; Syncope ; complications ; drug therapy ; physiopathology

BACKGROUNDSyncope is common in children and adolescents, with 15% estimated to have had at least one syncopal episode by age 18. In recent years, an increasing number of children, especially girls at their school age, have developed unexplained syncope. The mechanism of an unexplained syncope exhibited by children is incompletely studied; the association between different hemodynamic patterns and clinical features is also not clear. The aim of the study was to investigate the hemodynamic patterns of children with unexplained syncope and to examine the clinical relevance.

METHODSTwo hundred and eight children [87 boys, 121 girls, aged 3 - 19 years, mean (11.66 +/- 2.72) years] were selectively recruited from May 2000 to April 2006 when they presented syncope as their main complaint at the Multi-center Network for Childhood Syncope in Beijing, Hunan Province, Hubei Province, and Shanghai of China. All of the patients underwent head-up tilt tests; data were analyzed using SPSS version 10.0 for Windows. Continuous variables were expressed as the mean +/- standard deviation. Dichotomous variables were compared through a chi(2) test. A value of P < 0.05 (two sided) was regarded as statistically significant.

RESULTSThe age distribution of children with syncope was approximately normal. Head-up tilt tests was positive in 155 children, and the incidence of positive response of the baseline head-up tilt test for diagnosing unexplained syncope was 50.48%. The sensitivity value and diagnostic value of sublingual nitroglycerin head-up tilt test were both 74.52%. The hemodynamic pattern was normal in 53 children. The 155 children, who were positive in head-up tilt tests, showed signs of postural orthostatic tachycardia syndrome (60, 28.8%), the vasoinhibitory pattern (72, 34.6%), the cardioinhibitory pattern (5, 2.4%), and the mixed pattern (18, 8.7%). The gender distribution between the two age groups (age < 12 years vs age > or = 12 years) was not different (P > 0.05). The distribution of hemodynamic patterns between the children of the two age groups (age < 12 years vs age > or = 12 years), and the children with different complaints (dizziness vs syncope) was significantly different (P < 0.05), while the distribution between the children of different sexes and different lasting time of syncope (< or = 5 minutes vs > 5 minutes) was not significantly different (P > 0.05). Different hemodynamic patterns were differentiated by differing syncope inducements, presymptoms, and complicated symptoms during and after syncope.

CONCLUSIONThe tested girls were more prone when compared with the boys to have unexplained syncope, and the peak age was around twelve years old. The incidence of positive response of head-up tilt tests was also relatively higher for the girls. The distribution of hemodynamic patterns for different ages was different. For children with unexplained syncope, we should use head-up tilttests to distinguish the hemodynamic patterns in order to adopt rational therapeutic measures.

Adolescent ; Adult ; Blood Pressure ; Child ; Child, Preschool ; Female ; Humans ; Male ; Reflex ; Sex Characteristics ; Syncope ; diagnosis ; physiopathology ; Tilt-Table Test

We investigated the effect of beta-adrenergic stimulation on the heart rate and QT interval in syncope children with or without coexisting ventricular arrhythmias (VA). Of the 24 children who presented with syncope or presyncope and showed negative tilt test, 13 were classified into a group with VA and the remaining 11 without VA. The provocative test was performed in bolus infusion and continuous infusion. RR, QT, and QTc intervals on routine 12-lead surface electrocardiogram were obtained during each stage of isoproterenol infusion. In all cases, malignant ventricular arrhythmia and syncope were not induced by isoproterenol provocative test. RR and QT intervals were shortened and QTc intervals were prolonged as the isoproterenol dose was increased in both groups and methods. The QTc interval reached its peak level after the bolus injection of 1.0 microgram and during the continuous infusion of 0.03 microgram/kg/min. The two groups showed no significant difference in the QTc interval change according to the infusion methods. This study indicates that changes in the heart rate and QT interval by beta-adrenergic stimulation were not different according to the coexisting ventricular arrhythmias in syncope children with negative head-up tilt test.
Adolescent ; Adrenergic beta-Agonists/pharmacology* ; Arrhythmia/physiopathology* ; Child ; Child, Preschool ; Comorbidity ; Electrocardiography ; Female ; Heart Rate/drug effects* ; Heart Rate/physiology* ; Human ; Isoproterenol/pharmacology* ; Male ; Syncope/physiopathology*

OBJECTIVETo study the clinical value and safety of the head-up tilt table test (HUTT) in children under 6 years old.

METHODSThe HUTT results between September 2000 and August 2011 of 144 2 to 6-year-old children (81 boys and 63 girls) with syncope and dizziness of unknown causes were retrospectively studied.

RESULTSEight children completed the based tilt table test and 136 cases completed the sublingual nitroglycerin tilt table test. No serious side effects were found in these children. Thirty-two (22.2%) of the 144 children had a positive result of HUTT, including 18 boys and 14 girls (P>0.05). When HUTT-induced syncope met positive standards, ECG record and blood pressure recovered to normal levels within 5 minutes by changing the position of the test bed, keeping the airway open, nasal oxygen inhalation and oral milk.

CONCLUSIONSThe HUTT is valuable, safe and compliant in children under 6 years old.

Age Factors ; Blood Pressure ; drug effects ; Child ; Child, Preschool ; Dizziness ; diagnosis ; physiopathology ; Electrocardiography ; drug effects ; Female ; Humans ; Male ; Nitroglycerin ; pharmacology ; Retrospective Studies ; Syncope ; diagnosis ; physiopathology ; Tilt-Table Test

Adolescent ; Autonomic Nervous System ; physiopathology ; Blood Pressure ; physiology ; Blood Pressure Monitoring, Ambulatory ; methods ; Child ; Child, Preschool ; Circadian Rhythm ; Female ; Heart Rate ; physiology ; Humans ; Male ; Posture ; physiology ; Syncope, Vasovagal ; diagnosis ; etiology ; physiopathology ; Tilt-Table Test ; Vagus Nerve ; physiopathology

PURPOSE: An association between baroreflex sensitivity (BRS) and the response to tilt training has not been reported in patients with neurally mediated syncope (NMS). This study sought to investigate the role of BRS in predicting the response to tilt training in patients with NMS. MATERIALS AND METHODS: We analyzed 57 patients who underwent tilt training at our hospital. A responder to tilt training was defined as a patient with three consecutive negative responses to the head-up tilt test (HUT) during tilt training. RESULTS: After tilt training, 52 patients (91.2%) achieved three consecutive negative responses to the HUT. In the supine position before upright posture during the first session of tilt training for responders and non-responders, the mean BRS was 18.17+/-10.09 ms/mm Hg and 7.99+/-5.84 ms/mm Hg (p=0.008), respectively, and the frequency of BRS > or =8.945 ms/mm Hg was 45 (86.5%) and 1 (20.0%; p=0.004), respectively. Age, male gender, frequency of syncopal events before HUT, type of NMS, phase of positive HUT, total number of tilt training sessions, and mean time of tilt training did not differ between the study groups. In the multivariate analysis, BRS <8.945 ms/mm Hg in the supine position (odds ratio 23.10; 95% CI 1.20-443.59; p=0.037) was significantly and independently associated with non-response to tilt training. CONCLUSION: The BRS value in the supine position could be a predictor for determining the response to tilt training in patients with NMS who are being considered for inpatient tilt training.
Adult ; Aged ; Baroreflex/*physiology ; Blood Pressure ; Female ; Humans ; Male ; Middle Aged ; Multivariate Analysis ; Posture ; Predictive Value of Tests ; Sensitivity and Specificity ; Syncope, Vasovagal/*diagnosis/*physiopathology ; Tilt-Table Test/*methods ; Triazoles

Carotid Artery, Internal ; physiology ; Carotid Body Tumor ; blood supply ; complications ; surgery ; Carotid Sinus ; physiopathology ; Female ; Humans ; Middle Aged ; Syncope ; etiology ; Syndrome