Clinical values of creatine kinase and its isoenzymes in children and adolescents with vasovagal syncope.

BACKGROUND AND AIM: Vasovagal syncope (VVS) in children and adolescents is a common disorder. There may be an internal relationship between creatine kinase (CK) and its isoenzymes (CKMB) and syncope. The aim of this study was to evaluate the changes of CK and CKMB in children and adolescents with VVS. METHODS AND RESULTS: The VVS group included 218 patients (93 male and 125 female). The control group included 129 healthy children (78 male and 51 female). Serum CK and CKMB levels were estimated. We founded ①Serum CK and CK-MB levels decreased in VVS group than that in control group (P < 0.05). ②The CK levels of female were significantly lower than those of male in VVS group (P < 0.05). ③Serum level of CK-MB were in negative correlation with age, height, weight, BMI whereas in positively correlation with HR. ④CK was effected by CK-MB (ß = 0.147, P = 0.037) while CK-MB was independently influenced by age (ß = -0.203, P = 0.002) and DBP (ß = 0.171, P = 0.011). ⑤Both CK and CK-MB significantly influenced on VVS occurrence after adjusting for the effects of gender, age, height, weight, BMI and HR. CONCLUSION: The serum CK and CKMB levels decrease in children and adolescents with VVS. CK and CK-MB are the independent protective factors with VVS.

Serum Asymmetric Dimethylarginine Levels in Patients with Vasovagal Syncope.

Background and Objectives: Vasovagal syncope (VVS) is the most common cause of syncope and has multiple pathophysiological mechanisms. Asymmetric dimethylarginine (ADMA) is the major inhibitor of nitric oxide (NO). In this study, we aimed to investigate the relationship between plasma ADMA levels and syncope during the head-up tilt (HUT) test. Materials and Methods: Overall, 97 patients were included in this study. They were above 18 years of age and were admitted to our clinic with the complaint of at least one episode of syncope consistent with VVS. The HUT test was performed in all patients. Patients were divided into the following two groups based on the HUT test results: group 1 included 57 patients with a positive HUT test and group 2 included 35 patients with a negative HUT test. Blood samples were taken before and immediately after the HUT test to measure ADMA levels. Results: No significant intergroup differences were observed concerning gender and age (female gender 68% vs 60%; mean age 24.85 ± 4.01 vs 25.62 ± 3.54 years, respectively, for groups 1 and 2). ADMA values were similar between groups 1 and 2 before the HUT test [ADMA of 958 (544-1418) vs 951 (519-1269); p = 0.794]. In the negative HUT group, no significant differences were observed in ADMA levels before and after the HUT test [ADMA of 951 (519-1269) vs 951 (519-1566); p = 0.764]. However, in the positive HUT group, ADMA levels were significantly decreased following the HUT test [pretest ADMA of 958 (544-1418) vs post-test ADMA of 115 (67-198); p < 0.001]. Conclusion: ADMA levels significantly decreased after the HUT test in patients with VVS.

Cardiovascular biomarkers and echocardiographic findings at rest and during graded hypovolemic stress in women with recurrent vasovagal syncope.

INTRODUCTION: Vasovagal reflex is the most common type of syncope but its etiology is not fully elucidated. Venous return and cardiac output are key in hemodynamic control. The aim of the study was to assess cardiovascular biomarkers and echocardiographic measures at rest and during hypovolemia in women with and without a history of vasovagal syncope. METHODS: Fourteen women (aged 18-30) suffering from recurrent vasovagal syncope and 15 age-matched healthy women were included. Graded lower body negative pressure (LBNP) was used to create central hypovolemic stress until signs of presyncope occurred. Echocardiography was applied at rest and throughout LBNP. Cardiovascular biomarkers: copeptin, mid-regional proadrenomedullin, mid-regional pro-ANP, C-terminal proendothelin-1, and plasma norepinephrine were measured both at rest and throughout graded hypovolemia to presyncope. RESULTS: Women prone to vasovagal syncope presented with a narrower right ventricle (RV) (29 ± 1 vs 32 ± 1 mm, P < .05), smaller left atrium (36 ± 2 vs 47 ± 3 cm3 , P < .01) and lower cardiac output at rest (3.1 ± 0.2 vs 3.7 ± 0.2 L/min, P < .05) and during graded hypovolemia (P < .05). Copeptin was elevated at rest (4.3 ± 0.8 vs 2.5 ± 0.2 pmol/L, P < .05) and increased more in women with vasovagal syncope during progression of LBNP (P < .01). At rest, lower C-terminal proendothelin-1 (35 ± 5 vs 46 ± 2 pmol/L, P < .05) and higher norepinephrine levels (1.1 ± 0.1 vs 0.8 ± 0.1 nmol/L, P < .01) were seen in women with vasovagal syncope. CONCLUSION: Women prone to vasovagal syncope demonstrate reduced cardiac preload, lower cardiac output, as well as increased release of vasopressin in rest and during hypovolemic challenge. The results emphasize the importance of venous return and cardiac output in the pathogenesis of vasovagal syncope.

Troponin release after exertional vasovagal syncope.

Troponin release following exertional vasovagal syncope has not previously been reported. A young man was investigated after being admitted twice with exertional syncope, each time followed by a 10-fold spike in troponin I over 24 h. Treadmill exercise tests reproduced his symptoms and demonstrated a vasovagal mechanism. During recovery, despite lying supine, he remained hypotensive for 5 min, with profound bradycardia and ST segment depression. We suspected that intense cardiovagal neural activity may have caused the troponin leak.

Increased expression of blood muscarinic receptors in patients with reflex syncope.

AIMS: Pathophysiology of reflex syncope is not fully understood but a vagal overactivity might be involved in this syncope. Previously, overexpression of muscarinic M2 receptors and acetylcholinesterase was found in particular in the heart and in lymphocytes of rabbits with vagal overactivity as well as in hearts of Sudden Infant Death Syndromes. The aim of this present study was to look at M2 receptor expression in blood of patients with reflex syncope. The second objective was to measure acetylcholinesterase expression in these patients. METHODS AND RESULTS: 136 subjects were enrolled. This monocenter study pooled 45 adults exhibiting recurrent reflex syncope compared with 32 healthy adult volunteers (18-50 years) and 38 children exhibiting reflex syncope requiring hospitalization compared with 21 controls (1-17 years). One blood sample was taken from each subject and blood mRNA expression of M2 receptors was assessed by qRT-PCR. Taking into account the non-symmetric distributions of values in both groups, statistical interferences were assessed using bayesian techniques. A M2 receptor overexpression was observed in adult and pediatric patients compared to controls. The medians [q1;q3] were 0.9 [0.3;1.9] in patients versus 0.2 [0.1;1.0] in controls; the probability that M2 receptor expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.99. Acetylcholinesterase expression was also increased 0.7 [0.4;1.6] in patients versus 0.4 [0.2;1.1] in controls; the probability that acetylcholinesterase expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.97. Both in adults and children, the expression ratio of M2 receptors over acetylcholinesterase was greater in the patient group compared with the control group. CONCLUSION: M2 receptor overexpression has been detected in the blood of both, adults and children, exhibiting reflex syncope. As in our experimental model, i.e. rabbits with vagal overactivity, acetylcholinesterase overexpression was associated with M2 receptor overexpression. For the first time, biological abnormalities are identified in vagal syncope in which only clinical signs are, so far, taken into account for differential diagnosis and therapeutic management. Further work will be needed to validate potential biomarkers of risk or severity associated with the cholinergic system.

Impact of Cardiovascular Neurohormones on Onset of Vasovagal Syncope Induced by Head-up Tilt.

Background Vasovagal reflex is the most common form of syncope, but the pathophysiological mechanisms that initiate the reflex are not well understood. We aimed to study supine and early orthostatic levels of the neurohormones involved in control of circulatory homeostasis in relation to the onset of tilt-induced vasovagal syncope (VVS). Methods and Results A total of 827 patients who were investigated for unexplained syncope with head-up tilt test (HUT) and optional nitroglycerin provocation (Italian protocol) had blood samples collected while supine and after 3-minutes of HUT. Of these, 173 (20.9%) patients developed VVS during drug-free HUT, 161 of whom (males 44.7%; age 45±21 years) had complete data. We analyzed levels of epinephrine, norepinephrine, C-terminal pro-arginine vasopressin, C-terminal endothelin-1, and midregional fragments of pro-atrial natriuretic peptide and pro-adrenomedullin in relation to time from tilt-up to onset of VVS. We applied a linear regression model adjusted for age and sex. The mean time to syncope was 11±7 minutes. Older age (ß=0.13; SE=0.03, P<0.001), higher supine systolic blood pressure (ß=0.06; SE=0.03, P=0.02), and higher supine midregional fragment of pro-adrenomedullin predicted longer time to syncope (ß=2.31; SE=0.77, P=0.003), whereas supine levels of other neurohormones were not associated with time to syncope. Among 151 patients who developed VVS later than 3 minutes of HUT, increase in epinephrine (ß=-3.24; SE=0.78, P<0.001) and C-terminal pro-arginine vasopressin (ß=-2.07; SE=0.61, P=0.001) at 3 minutes of HUT were related to shorter time to syncope. Conclusions Older age, higher blood pressure, and higher level of pro-adrenomedullin are associated with later onset of VVS during tilt testing, whereas greater increase of tilt-induced epinephrine and vasopressin release correlate with shorter time to syncope.

Greater early epinephrine rise with head-up posture: A marker of increased syncope susceptibility in vasovagal fainters.

BACKGROUND: Head-up tilt (HUT) is widely used for diagnostic evaluation of patients with suspected vasovagal syncope (VVS), but also offers an opportunity to study VVS pathophysiology. In this regard, it is known that plasma epinephrine (Epi) levels and Epi/norepinephrine (NE) ratio are markedly increased from baseline at the time of HUT-induced VVS. However, whether these changes contribute to VVS susceptibility remains uncertain. OBJECTIVE: We hypothesized that if catecholamines contributed to VVS directly, then a greater increase of plasma Epi and Epi/NE ratio early during HUT would be associated with shorter time to syncope. METHODS: The patient population comprised 33 individuals (14 men, 43 ± 2 years) with suspected VVS in whom 70° HUT reproduced symptoms. Arterial Epi and NE concentrations were collected at baseline (supine) and 2 minutes of HUT. Linear, exponential, and multiple regression were used to access the association between changing catecholamine levels and time to syncope. RESULTS: Mean ± SD time to positive HUT was 11 (7.6) minutes. Higher plasma Epi levels (pg/mL) both at baseline and at 2 minutes upright correlated with shorter time to syncope (baseline, R = -0.35, P = 0.048; and 2 minutes, R = -0.58, P = 0.001). Similarly, a greater Epi/NE ratio at 2 minutes head-up correlated with earlier time to syncope (R = -0.49, P = 0.007). These relationships remained significant after adjusting for age and sex (P = 0.006 and 0.02, respectively). CONCLUSION: Greater Epi levels and Epi/NE ratio early during HUT were associated with shorter time to VVS, suggesting a possible contribution to VVS susceptibility.

[Comparison of curative effect and serum electrolytes between different oral rehydration salts in treatment of neurally mediated syncope children].

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 (χ2=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 (χ2=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.

Serum vitamin B-12 in children presenting with vasovagal syncope.

BACKGROUND AND OBJECTIVES: The present study aims to determine the serum vitamin B-12 in children presenting with vasovagal syncope. METHODS AND STUDY DESIGN: This is a prospective review of 160 children presenting with vasovagal syncope. Subgroup analysis was done based on the results of head up tilt test. RESULTS: Head up tilt test gave positive results in 80 children and yielded negative results in the remaining 80 children. The tilt test positive children had significantly lower thyroid stimulating hormone concentrations (p=0.06), total iron binding capacity (p=0.04) and serum vitamin B-12 (p=0.01). The prevalence of vitamin B-12 deficiency was significantly higher in the tilt positive group (80% vs 52.5%, p=0.001). Out of 80 children with positive tilt test, 8 children (10%) showed cardioinhibitory response, 22 children (27.5%) demonstrated a vasodepressor response, 24 children (30%) displayed mixed response and 26 children (32.5%) had the postural orthostatic tachycardia syndrome. Erythrocyte sedimentation rate was significantly lower in the mixed response group than in the vasodepressor group (6.2±0.8 mm/h vs 14.3±2.5 mm/h, p=0.001). Serum vitamin B-12 was significantly lower in the postural orthostatic tachycardia syndrome (POTS) group than in the vasodepressor group (240.8±38.2 pg/mL vs 392.7±27.1 pg/mL, p=0.001). The prevalence of vitamin B-12 deficiency was significantly higher in the POTS group than in the vasodepressor group (92.3% vs 45.5%, p=0.001). CONCLUSIONS: Vitamin B-12 deficiency causes reduction in myelinization, deceleration in nerve conduction and elevation in serum concentrations of noradrenaline. These factors may contribute to the impairment of autonomic functions which are involved in the pathogenesis of vasovagal syncope.

Plasma Neuropeptide Y Levels in Vasovagal Syncope in Children.

BACKGROUND: Vasovagal syncope (VVS) is the most common cause of syncope in children. Neuropeptide Y (NPY) plays an important role in the regulation of blood pressure (BP), as well as myocardial contractility. This study aimed to explore the role of plasma NPY in VVS in children. METHODS: Fifty-six children who were diagnosed with VVS (VVS group) using head-up tilt test (HUT) and 31 healthy children who were selected as controls (control group) were enrolled. Plasma NPY concentrations were detected. The independent t-test was used to compare the data of the VVS group with those of the control group. The changes in plasma NPY levels in the VVS group during the HUT, as well as hemodynamic parameters, such as heart rate (HR), BP, total peripheral vascular resistance (TPVR), and cardiac output (CO), were evaluated using the paired t-test. Furthermore, the correlations between plasma NPY levels and hemodynamic parameters were analyzed using bivariate correlation analysis. RESULTS: The BP, HR, and plasma NPY (0.34 ± 0.12 pg/ml vs. 0.46 ± 0.13 pg/ml) levels in the supine position were statistically low in the VVS group compared to levels in the control group (all P < 0.05). Plasma NPY levels were positively correlated with the HR (Pearson, R = 0.395, P < 0.001) and diastolic BP (Pearson, R = 0.311, P = 0.003) when patients were in the supine position. When patients in the VVS group were in the supine position, elevated TPVR (4.6 ± 3.7 mmHg·min-1·L-1 vs. 2.5 ± 1.0 mmHg·min-1·L-1, respectively, P < 0.001; 1 mmHg = 0.133 kPa) and reduced CO (1.0 ± 0.7 L/min vs. 2.4 ± 1.3 L/min, respectively, P < 0.001) were observed in the positive-response period compared with baseline values. The plasma NPY levels were positively correlated with TPVR (Spearman, R = 0.294, P = 0.028) but negatively correlated with CO in the positive-response period during HUT (Spearman, R = -0.318, P = 0.017). CONCLUSIONS: Plasma NPY may contribute to the pathogenesis of VVS by increasing the TPVR and decreasing the CO during orthostatic regulation.

Copeptin levels in patients with vasovagal syncope.

BACKGROUND AND PURPOSE: Vasovagal syncope (VVS) is linked to more than one pathophysiologic mechanisms. Copeptin, an emerging cardiovascular marker, is a surrogate for arginine-vasopressin, which increases following VVS. We aimed to assess the dynamic pattern of copeptin levels in typical VVS, categorized by the degree of vasoconstriction during orthostasis, and healthy controls. METHODS: The following groups were studied: Group A (n=21), with adequate limb vasoconstriction during the first min. of tilt, assessed by limb plethysmography (at least 30% flow reduction); Group B (n=15), showing impaired vasoconstriction during orthostasis (<10% reduction); Group C (n=18), history of VVS and negative tilt test result; Group D (n=18), healthy controls. Copeptin plasma levels were assessed before and 5min following tilt test positivity or termination. RESULTS: Baseline copeptin values were similar in all groups (8.3±6.4 in Group A, 5.7±2.3pmol/l in B, 6.0±1.9 in C, and 6.9±2.6 in D, p: 0.41). Significant increases in copeptin during tilt were observed in all Groups of VVS patients (A, B, C), including those with negative tilt (Group C: from 6.0±1.9 to 27.7±12.6pmol/l, p: 0.001), but not in controls. Following tilt termination, a greater increase was observed in copeptin values in Group B vs all other Groups A, C, and D (111.6±63.5 vs 29.5±51.3, 27.7±12.6, and 8.3±2.9, respectively). CONCLUSIONS: Copeptin increases following tilt not only in VVS with a positive response, but also in typical history patients with a negative test. Increased copeptin levels following orthostasis may be useful for diagnosing VVS.

Significance of red cell distribution width in the differential diagnosis between neurally mediated syncope and arrhythmic syncope in children.

OBJECTIVES: The aim of the present study was to explore the predictive value of red cell distribution width as a means to differentiate between neurally mediated syncope and arrhythmic syncope in children. METHOD: Patients were divided into a neurally mediated syncope group (n=72) and an arrhythmic syncope group (n=21) on the basis of clinical history, results of the head-up tilt test, electrocardiography, and 24-hour ambulatory electrocardiography. As controls, we recruited 55 healthy children. Red cell distribution width was determined for children in all groups. A receiver operating characteristic curve was drawn to study the predictive effect of red cell distribution width to differentiate between neurally mediated syncope and arrhythmic syncope. RESULTS: Red cell distribution width was significantly higher in children with neurally mediated syncope than in children with arrhythmic syncope and the control group. A receiver operating characteristic curve on the predictive value of red cell distribution width in differentiating neurally mediated syncope from arrhythmic syncope showed that the area under the curve was 0.841 (95% confidence interval: 0.737-0.945, p<0.05). A red cell distribution width value of 12.8% as the cut-off value yielded a sensitivity of 80.6% and a specificity of 76.2% in discriminating between patients with neurally mediated syncope and arrhythmic syncope. CONCLUSION: Red cell distribution width value of ⩾12.8% might be a useful adjunct for primary-care physicians to differentiate neurally mediated syncope from arrhythmic syncope in children.

Impact of Elevated Hemoglobin and Serum Protein on Vasovagal Reaction from Blood Donation.

We conducted a cross-sectional study to elucidate factors contributing to vasovagal reaction (VVR), the most frequent side effect following whole blood and apheresis donations. Complications recorded at the collection sites after voluntary donations by the Japanese Red Cross Tokyo Blood Center (JRC), in the 2006 and 2007 fiscal years, were analyzed by both univariate analysis and the multivariate conditional logistic regression model. Of 1,119,716 blood donations over the full two years, complications were recorded for 13,320 donations (1.18%), among which 67% were VVR. There were 4,303 VVR cases which had sufficient information and could be used for this study. For each VVR case, two sex- and age-matched controls (n = 8,606) were randomly selected from the donors without complications. Age, sex, body mass index (BMI), predonation blood pressure, pulse and blood test results, including total protein, albumin, and hemoglobin, were compared between the VVR group and the control group. In univariate analysis, the VVR group was significantly younger, with a lower BMI, higher blood pressure and higher blood protein and hemoglobin levels than the control group (p<0.001). Furthermore, blood protein and hemoglobin levels showed dose-dependent relationships with VVR incidences by the Cochran-Armitage trend test (p<0.01). For both sexes, after adjusting for confounders with the multivariate conditional logistic regression model, the higher than median groups for total protein (male: OR 1.97; 95%CI 1.76,-2.21; female: OR 2.29; 95%CI 2.05-2.56), albumin (male: 1.75; 1.55-1.96; female: 1.76; 1.57-1.97) and hemoglobin (male: 1.98; 1.76-2.22; female: 1.62; 1.45-1.81) had statistically significant higher risk of VVR compared to the lower than median groups. These elevated serum protein and hemoglobin levels might offer new indicators to help understand VVR occurrence.

Assessment of endothelin and copeptin as biomarkers for vasovagal syncope.

BACKGROUND: The diagnosis of vasovagal syncope continues to be difficult despite the use of accurate histories, tilt testing and implantable loop recorders. A circulating biomarker might be useful to facilitate diagnoses. Both endothelin-1 and vasopressin are increased during positive tilt tests resulting in syncope. Copeptin is a stable cleavage product of vasopressin formation. We conducted a pilot study to assess the utility of endothelin-1 and copeptin as circulating biomarkers of vasovagal syncope. METHODS: Three populations were studied: syncope patients, epilepsy patients and controls. Vasovagal syncope diagnosis was ascertained with the Calgary Syncope Score and epilepsy diagnosis was confirmed with EEG. Plasma levels of endothelin-1 were measured using by ELISA and copeptin levels were determined using an EIA kit. RESULTS: Asymptomatic control subjects had mean age 35 ± 11 years (7/22 male); epileptic subjects had mean age 32 ± 7 years (4/15 male); and syncope subjects had mean age 33 ± 16 years (4 of 21 male). Circulating plasma levels of endothelin-1 and copeptin were no different among the three groups. Mean concentrations of endothelin-1 were as follows: syncope, 23 ± 32 pg/mL; controls, 21 ± 17 pg/mL; and epileptics, 18 ± 12 pg/mL. Mean concentrations of copeptin were as follows: syncope, 1·29 ± 0·79 ng/mL; controls, 1·25 ± 0·79 ng/mL; and seizures, 1·23 ± 0·45 ng/mL. There were no significant correlations between syncope frequency and copeptin or endothelin-1 levels. CONCLUSION: Circulating plasma endothelin-1 and copeptin levels are not significantly different among populations of controls, syncope patients and seizure patients.

Autonomic activity and biomarker behavior in supine position and after passive postural stress in different orthostatic intolerance syndromes.

INTRODUCTION AND OBJECTIVES: Orthostatic intolerance (OI) syndromes are a confusing topic and determining a specific diagnosis to achieve optimal treatment can be troublesome. We sought to assess biomarker, hemodynamic and autonomic variables in OI patients (autonomic dysfunction [AD], postural orthostatic tachycardia syndrome [POTS] and neurally mediated syncope [NMS]) and healthy controls during supine and head-up tilt position in order to achieve a better diagnosis. RESULTS: In response to head-up tilt, patients with AD presented a marked decrease in systolic blood pressure (SBP) (p=0.002), and a blunted increase in heart rate (HR) (p=0.04). Baroreceptor gain was almost absent in supine position and did not change in response to tilt. Patients with POTS had lower values of atrial natriuretic peptide (p=0.03) but similar neurohormonal biomarkers and hemodynamic and baroreceptor function in supine position compared to healthy subjects. However, in response to head-up tilting greater reductions in stroke volume (p=0.008) and baroreceptor gain (p=0.002) and greater rises in HR (p=0.001), total peripheral resistance (p=0.008), low frequency component of SBP variability (LF-SBP) (p=0.003) and plasma noradrenaline (p=0.03) were observed. Patients with NCS had similar biomarkers and autonomic indices to healthy subjects in supine position, but a larger decrease in baroreceptor gain (p=0.007) and a greater rise in LF-SBP (p=0.004) and plasma adrenaline (p=0.003) response to head-up tilting. CONCLUSION: Although different OI syndromes share similar symptoms, including blurred vision, syncope and dizziness particularly during orthostatism, they differ markedly regarding biochemical, autonomic and hemodynamic parameters. Assessment of these differences may be helpful for better diagnosis and management.

Clinical Indications and Adverse Reactions of Platelet Apheresis.

OBJECTIVE: To determine the clinical indications and adverse reactions of platelet apheresis procedure. STUDY DESIGN: Cross-sectional, observational study. PLACE AND DURATION OF STUDY: Blood Bank of Pakistan Atomic Energy Commission General Hospital, Islamabad, from January 2010 to December 2014. METHODOLOGY: Indications and adverse reaction verified for 200 consecutive platelet apheresis donations performed for 125 patients was included in this study. Data was analysed for descriptive variables using SPSS version 16. RESULTS: Donor deferral rate in the study was 63.83%. All the donors were males (100%) and replacement donors. Most prevalent blood type was B-positive (n=63, 31.5%), followed by O-positive (n=59, 29.5%). Rh negative groups constituted 13.5% (n=27) of all the donors. Average age of platelet apheresis donors was 28.56 ± 5.77 years. Maximum numbers of donors were in age range 20 - 30 years. Average weight of the donors was 73.96 ± 11.96 kg. Mean pre-procedure platelet count of donors was 268,000/µL. The postprocedure average platelet count was approximately 200,000/µL. The mean duration of a platelet apheresis session was 78.27 ± 26.07 minutes. Average volume of the final product was 412.53 ± 45.33 ml. Average volume of anti-coagulant acid citrate dextrose used per procedure was 300 ± 40 ml, 245 ml returned to donor along with returned blood while 55 ml used as anticoagulant in final concentrate. Of total 200, two (1%) final products were contaminated with red cells. Three (1.5%) products were not issued and finally expired. Of the 125 patients for which plateletpheresis procedures were performed, 54 (43.2%) patients were males and 71 (56.8%) were females (M: F=0.76:1). Six donors (3%) had adverse events: three donors (1.5%) had mild reactions, two (1%) moderate reaction, and one donor (0.5%) developing hematoma. None had severe or life-threatening reactions. CONCLUSION: Plateletpheresis procedure is relatively safe and forms an important adjuvant to blood bank inventory.

Erythrocytic hydrogen sulfide production is increased in children with vasovagal syncope.

OBJECTIVES: To explore the differences in erythrocyte hydrogen sulfide (H2S) production in children with vasovagal syncope (VVS). STUDY DESIGN: A total of 54 children including 27 with VVS, aged 6-16 years (mean age 11.3 ± 3.3 years), and 27 healthy children, aged 3-17 years (mean age 10.4 ± 1.8 years) were included in the study. Children with VVS had symptoms of dizziness, pallor, blurred vision, nausea, and some had syncope. Erythrocyte H2S production was measured by a sulphur-sensitive electrode. Flow-mediated dilation (FMD) of brachial artery was measured for each patient by vascular ultrasound. RESULTS: H2S production from erythrocytes was significantly increased in the children with VVS compared with controls (P < .01). The erythrocytic H2S production in the VVS-vasoinhibitory subgroup was obviously higher than that in VVS-cardioinhibitory (P < .05) and VVS-mixed inhibitory subgroups (P < .05). FMD in the VVS-vasoinhibitory subgroup was greater than that in the VVS-cardioinhibitory (P < .05) and the VVS-mixed subgroups (P < .05). The erythrocytic H2S production had a positive linear correlation with FMD in children with VVS (P < .05). CONCLUSIONS: Increased erythrocyte H2S production may be involved in the pathogenesis of VVS in children.

Near-infrared Spectroscopy to Assess Cerebral Perfusion during Head-up Tilt-table Test in Patients with Syncope.

OBJECTIVE: Neurocardiogenic syncope (NCS) is the most common cause of syncope in children and adolescents. Neurocardiogenic syncope occurs secondary to cerebral hypotension because of bradycardia, hypotension, or both. Head-up tilt-table test (HUTT) is the primary diagnostic test. Near-infrared spectroscopy (NIRS) is a noninvasive technology that directly monitors trends in regional tissue oxygen saturations over a specific body region. Placing an NIRS probe over the temporal region allows an indirect measurement of cerebral perfusion. Our hypothesis is that regional tissue oxygen saturation will decrease during an NCS episode and will remain stable in patients without syncope. PATIENTS AND DESIGN: The investigators conducted a retrospective review of all HUTT utilizing cephalic NIRS performed at our institution from August 2012 to January 2013. Tests were classified as positive, negative, or psychogenic reactions. Paired t-test was used to determine statistical significance of NIRS changes and one-way analysis of variance was used to analyze baseline characteristics among the three groups. RESULTS: Twelve patients were included in the study (female = 10). The average age was 14.4 years (range: 12-17). Five tests were positive for NCS, four were negative, and three demonstrated psychogenic reactions. Patients with a positive test had a sudden, significant decrease in regional tissue oxygen saturations (P = .009) by an average of 11.3 ± 5.2% compared with baseline. The decrease in regional tissue oxygen saturation preceded symptoms, hypotension, and bradycardia in all patients. Regional tissue oxygen saturation levels remained stable in patients with a negative test or psychogenic syncope. CONCLUSIONS: NIRS monitoring during HUTT produces a reliable, positive result that precedes clinical signs and symptoms. Further, it helps distinguish NCS from psychogenic syncope.

[Signification of NT-proBNP in the differential diagnosis of syncope in adults]. / Znaczenie NT-proBNP w diagnostyce róznicowej omdlen u osób doroslych.

Syncope is a transient loss of consciousness, which is the result of global brain hypoperfusion, characterized by rapid onset, short duration, and spontaneous complete resolution. Syncope is a common clinical problem due to its complex, multi-causal etiology, not completely understood pathogenesis and potential complications. Diagnosis of syncope is often associated with the implementation of many medical tests. In the recent years, the role of determining the concentration of NT-proBNP in the differential diagnosis of syncope has been highlighted. Aims of the study was analysis of NT-proBNP concentrations in patients with cardiogenic syncope in comparison to patients with neurogenic syncope and determination of the threshold value of NT-proBNP to differentiate cardiac and neurogenic syncope and to determine its sensitivity and specificity. The study included 160 pts (64 man, 96 women), aged 18 - 77 yrs (mean age 50,6) with a reflex syncope (group I) or cardiac syncope (group II). To determine the etiology of syncope, collected were: medical history for symptoms and circumstances of the syncope, measurements of blood pressure, resting ECG recording, cardiac echocardiography, and the concentration of NT-proBNP levels. Results: the group I included 80 pts (29 men, 51 women), aged 18 - 72 yrs (mean age 41.2). Group II included 80 pts (35 man, 45 women), aged 38 - 77 yrs (mean age 62.1). The assessment of concentrations of NT-proBNP showed significantly higher levels in group II than group I (467.6 +/- 227.4 vs 64.1 +/- 59.1; p <0.0001). In patients with arrhythmias and conduction abnormalities, the levels of NT-proBNP were higher in comparison to those without such disorders (364 +/- 249 vs. 171 +/- 209 pg/ml, p < 0.001). It was found that the concentration of NT-proBNP at 230.6 pg/ml might be a cut-off point that allows the prediction of cardiogenic cause of syncope with 96% specificity, 92% sensitivity and 93% negative predictive value. Conclusions: 1. The concentration of peptide NT-proBNP patients with reflex syncope. 2. It was shown that the cut off concentration of the NT-proBNP equal 230.6 pg/ml is characterized by the high sensitivity, specificity, and negative predictive value in determining the etiology of syncope.