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The effect of the rapid redistribution of blood during head-up tilt tests in 21-day Dry Immersion suddenly became relevant in connection with the occurrence of mild hemorrhagic syndrome in the study participants. It became necessary to analyze the processes of occurrence of hemorrhagic syndrome as orthostatic and congestive purpura. The aim of this work was to study the features of the proteomic response of the human body to the rapid redistribution of blood during head-up tilt tests during 21-day immersion, which led to stagnant and orthostatic purpura. According to the results of examination of 10 healthy male volunteers aged 23–34 years after head-up tilt tests, pitting edema and local petechial hemorrhages in the soft tissues of the legs and feet were observed. Proteomic analysis of the samples was carried out by high performance liquid chromatography with tandem mass spectrometry. For bioinformatic analysis, the software packages Perseus, ANDSystem were used. From reliably different (p-value

Autonomic disorders are common in patients with systemic lupus erythematosus (SLE), but the therapeutic strategy and methods for evaluating the effects of therapy have not been established. We describe the three cases of SLE patients who developed severe autonomic disorders as demonstrated by the head-up tilt table test (HUT). All three patients were treated by intensive immunosuppressive treatments including intravenous cyclophosphamide (IVCY); their HUT results all became negative. Our cases suggest that IVCY treatment can be a good therapeutic option for severe autonomic disorders in SLE patients. The HUT is a useful objective method for the diagnosis of and the evaluation of longitudinal therapeutic effects on autonomic disorders in SLE patients with orthostatic intolerance., Modern Rheumatology Case Reports, 6 (1), pp. 47-51; 2022

Previous studies have demonstrated that sympathetic baroreflex sensitivity (BRS) increases during orthostatic stress in humans. We recently showed that dietary salt intake affects sympathetic neural control in healthy premenopausal women. This study aimed to determine whether salt loading versus salt reduction would impact sympathetic BRS during orthostasis in premenopausal women with a history of normal pregnancy. Nine healthy women [42 ± 3 (SD) yr] were given a standardized isocaloric high-salt (250 mEq sodium/day) or low-salt (50 mEq sodium/day) diet for 1 wk each (∼2 mo apart with the order randomized), whereas water intake was ad libitum. Laboratory testing was performed following each high- and low-salt period in the midluteal phase of the menstrual cycle. Hemodynamics and muscle sympathetic nerve activity (MSNA) were measured at baseline (supine; 2 min) and during a graded head-up tilt (30° for 5 min and 60° for 20 min). Sympathetic BRS was assessed during baseline and head-up tilt. Hemodynamics were not different between salt conditions during baseline or tilt. Both supine and upright MSNA indices were lower in high salt than low salt (all P < 0.05), however, there was no interaction effect ( P = 0.507–0.996). On moving from supine to upright, sympathetic BRS remained unchanged in high salt but increased in low salt ( P = 0.028 for interaction). Thus, salt loading diminishes the responsiveness of sympathetic BRS during orthostasis compared with salt reduction in healthy premenopausal women with prior normal pregnancy. Whether this is one underlying mechanism for salt-induced development of hypertension during ambulation remains to be determined.

Previous research suggests individuals with intellectual disabilities (ID) may experience autonomic dysfunction, however, this has not been thoroughly investigated. The aim of this study was to compare the autonomic response to standing up (active orthostasis) and head-up tilt (passive orthostasis) in individuals with ID to a control group without ID. Eighteen individuals with and 18 individuals without ID were instrumented with an ECG-lead and finger-photoplethysmography for continuous heart rate and blood pressure recordings. The active and passive orthostasis protocol consisted of 10-min supine rest, 10-min standing, 10-min supine recovery, 5-min head-up tilt at 70, followed by 10-min supine recovery. The last 5 min of each position was used to calculate hemodynamic and autonomic function (time- and frequency-domain heart rate and blood pressure variability measures and baroreflex sensitivity). Individuals with ID had higher heart rate during baseline and recovery (P < 0.05), and an attenuated hemodynamic (stroke volume, heart rate) and heart rate variability response to active and passive orthostasis (interaction effect P < 0.05) compared with individuals without ID. Mean arterial pressure (MAP) was higher in individuals with ID at all timepoints. Individuals with ID demonstrated altered hemodynamic and autonomic regulation compared with a sex- and age-matched control group, evidenced by a higher mean arterial pressure and a reduced response in parasympathetic modulation to active and passive orthostasis. NEW & NOTEWORTHY Individuals with ID demonstrated altered hemodynamic and autonomic regulation to the clinical autonomic function tasks standing up and head-up tilt (active and passive orthostasis). Higher resting heart rate and higher MAP throughout the protocol suggest a higher arousal level, and individuals with ID showed a blunted response in parasympathetic modulation. Further research should investigate the relationship of these findings with clinical outcomes.

Increased pulse wave velocity (PWV), a marker of cardiovascular disease (CVD), has been reported in otherwise healthy individuals with spinal cord injury (SCI) compared with age-matched uninjured controls. Due to decentralized descending sympathetic vascular control, individuals with injuries above T6 are prone to orthostatic hypotension and, as a result, depend on the renin-angiotensin-aldosterone system (RAAS) to maintain orthostatic blood pressure (BP). The purpose of this study was to determine resting PWV, a noninvasive surrogate of central arterial stiffness, in individuals with cervical (C4-T1

[Background] The European Syncope Guidelines (ESG) recommend the use of Head-up tilt test (HUT) in case of suspicion of vasovagal syncope (VVS) or orthostatic hypotensive syncope (OHS) after an adequate initial inconclusive evaluation. We report a single center experience in the scenario of suspected VVS or OHS, who underwent HUT in patients referred to a Syncope Clinic after ruling out high-risk causes., [Methods] We prospectively and consecutively included all syncopal patients that were referred for HUT, by their attending physician after performing a series of diagnostic tests to rule out cardiac etiology. The clinical history and diagnostic tests performed were reviewed prior to HUT. Patients were pre-classified according to the recommendations from the ESG as; VVS, OHS or Syncope of Unknown Etiology (SUE)., [Results] We studied 1058 patients, 558 (52.7%) males, mean age 46.5 ± 20.1 yr. There were no gender differences in age, risk factors, previous heart diseases, ECG findings or number of previous tests. Based on the ESG criteria a significant number of diagnostic tests were probably unnecessarily performed. HUT was positive in 609 patients (57.5%). The rate of positive HUT according to pre-classification was significantly different among groups: 60% VVS, 46.1% OHS and 54.3% SUE (p = 0.037). Combining ESG recommendations and HUT results of the 1058 resulted in 762 (72%) diagnosed as VVS, 89 (8.4%) as OHS and 207 (19.5%) as SUE., [Conclusions] Appropriate application of ESG recommendations combined with HUT, identified 81% of patients with non-cardiogenic syncope, potentially avoiding a significant number of unnecessary diagnostic tests.

Fainting and loss of consciousness (including syncope) are one of the most common causes of medical consultations. A detailed history is of particular importance in their diagnosis. It allows to select a group of patients with a high risk of life-threatening condition and to direct further interdisciplinary process with the participation of a cardiologist, neurologist, psychiatrist and psychologist. The head-up tilt test (HUTT) has a special place in the diagnosis of neurocardiogenic syncope. The main purpose of this review is to highlight the indications for HUTT and indicate situations in which it should be avoided due to the lack of added value of the applied therapy.

Objective: This systematic review analysed the evidence for the effect of head-up tilt (passive-standing) on consciousness among persons in prolonged disorders of consciousness. Data sources: Articles were identified through primary database searching (Medline, CINAHL, AMED, The Cochrane Library) and post-citation searching (Scopus). Review methods: This review followed the PRISMA statement. The search strategy was created to find articles that combined any conceivable passive standing device, any measure of consciousness and disorders of consciousness of any origin. Inclusion criteria were any papers that evaluated the use of head-up tilt in adults in defined disorders of consciousness. Exclusion criteria included active stand studies, paediatric studies and animal studies. The search was completed independently by two researchers. Data collection and risk of bias assessment was completed using the Downs and Black tool. Results: 6867 titles were retrieved (last search completed 21/6/20). Ten papers met the inclusion criteria: five examined the effects of a single head-up tilt treatment, and five the effects of head-up tilt regimes. Eighty-seven participants were randomised in three randomised controlled trials. In the remaining preliminary studies or case series, 233 participants were analysed. Quality was low, with only two high-quality studies available. Four studies were suitable for effect size analysis, where medium to large effect sizes were found. The two high-quality studies found head-up tilt had a large effect on consciousness. Conclusion: Overall there is some evidence that repeated passive standing on a tilt-table can improve consciousness, but the relevant studies provoke further questions.

Background: Tilt table test is used for the last few decades to detect cause in unexplained syncope. The response to tilting may vary physiologically with obesity. Objective: To assess the relationship of BMI to cardiovascular response to tilting. Methods: This experimental study was conducted from March 2019 to Feb 2020 on 90 healthy subjects with different BMI. Fifty one subjects of both gender with BMI 18.5-24.9 kg/m2 were included in the non-obese group and 39 subjects of both gender with BMI of 25-29.9 kg/m2 were included in overweight group and they were further subdivided into male and female. Head up tilting was done for 10 minutes at 600 by using a motorized tilt table. Systolic blood pressure (SBP), diastolic blood pressure (DBP) were recorded by an automatic sphygmomanometer. Heart rate (HR) and peripheral capillary oxygen saturation (SpO2) were measured by a pulse oximeter. For statistical analysis, Independent sample ‘t’ test, Pearson’s correlation test and Chi square tests were applied. Results: Significantly smaller rise of heart rate was observed in overweight males and greater fall of systolic blood pressure was observed in overweight females. Conclusion: This study concluded that over weight is associated with reduced orthostatic tolerance to head up tilt test in both genders. J Bangladesh Soc Physiol. 2020, June; 15(1): 6-10

Objective: To develop an orthostatic intolerance symptom scoring system to assess orthostatic intolerance and then to compare the symptom score among different head-up tilt test responses. Methods: 272 subjects (5-18 years) presenting with orthostatic intolerance symptoms finished questionnaire and head-up tilt test. According to head-up tilt test hemodynamic responses, the subjects were divided into head-up tilt test negative, vasovagal syncope, and postural tachycardia syndrome groups. Results: We built up a symptom score according to the frequency of dizziness, headache, blurred vision, palpitations, chest discomfort, gastrointestinal symptoms, profuse perspiration, and syncope. The median score in postural tachycardia syndrome subjects was highest. A score of 2.5 for predicting vasovagal syncope yielded a sensitivity of 75.0% and specificity of 50.3%, a score of 5.5 for predicting postural tachycardia syndrome yielded a sensitivity of 69.7% and specificity of 72.0%. Furthermore, the median score in postural tachycardia syndrome subjects was significantly higher than that in head-up tilt test negative subjects with heart rate increment of 30-39 beats/min ( P < .01). Conclusions: This suggests that the symptom score has some predictive value in head-up tilt test results, which can be served as a preliminary assessment instrument.

Background: A tilt table test is a useful, non-invasive technique that has been used for the last few decades to detect autonomic failure. The response to tilting may vary physiologically between sexes. Aim of the study: To assess the gender-specific changes in cardiovascular response to a tilt test in healthy subjects. Materials and Methods: This experimental study was conducted on 90 healthy males and females aged 18 - 60 years, from 2019 to 2020. Forty- five male subjects and 45 female subjects were included. Using a motorized tilt table, a tilt table test was performed at 60 degrees for 10 minutes. An automatic sphygmomanometer was used to measure blood pressure (BP), and heart rate (HR) and a pulse oximeter was used for the measurement of peripheral capillary oxygen saturation (SpO2). An independent sample t test, a multiple regression analysis and a chi squared test were conducted for statistical analyses. Results: A significantly greater drop in systolic blood pressure (SBP) was observed in females, compared to males after tilting. In 5.5% of the subjects, orthostatic intolerance occurred, but there were no significant age or gender- specific differences in subjects with orthostatic intolerance. Conclusion: This study concluded that in response to tilting, cardiovascular response was less pronounced in females.

Head-up tilt test (HUTT) is a reasonable diagnostic evaluation for patients with suspected vasovagal syncope; however, its lengthy duration is a remarkable limitation. Although adenosine (AD), as an alternative provocative agent, is a promising option for tackling this shortcoming, it received little appreciation in the literature. We aimed to compare the efficacy and the time to elicit a positive response to HUTT for sublingual trinitroglycerin (TNG) and intravenous AD. Furthermore, we evaluated patients’ outcomes in the follow-up. Patients with a chief complaint of transient loss of consciousness (TLOC) were evaluated. We randomized patients with the diagnosis of unexplained syncope after diagnostic evaluations, to undergo TNG-augmented HUTT or AD-augmented HUTT. They were crossed over to receive the other medication in case of negative response to the test. In the follow-up, we evaluated traumatic and non-traumatic TLOCs, hospitalization due to syncope, and death in patients. We randomized 132 patients (41.70 ± 19.37 years, 52.3% female) to receive TNG (n = 66) or AD (n = 66). Respectively, the positivity rate of TNG and AD for the first and the crossover-HUTT was 31.1% and 26.7%, and 20.5% and 26.2% with no statistically significant differences in both tests (P ˃ 0.50). The time to positive response was significantly shorter for AD than TNG (P < 0.001). In the follow-up, re-admission was significantly more prevalent in HUTT-negative patients compared to HUTT-positive patients (P = 0.04). We found that diagnostic yield of TNG and AD in HUTT is comparable, while AD acts 4 times faster than TNG in evoking a vasovagal response.

Objectives: To compare the levels of cortisol in patients of vasovagal syncope (VVS) and postural tachycardia syndrome (POTS). Methods: A cross-sectional analytical study was conducted at Islamic International Medical College, Rawalpindi and Electrophysiology Department at (AFIC). This study included 80 subjects, comprising of 35 patients in each group of vasovagal syncope and postural tachycardia syndrome and 10 healthy subjects. Patients with complaint of syncope was evaluated for vasovagal syncope and postural tachycardia syndrome using Head Up Tilt Test (HUTT). Blood samples of all the participants were taken and serum cortisol was analyzed using ELISA method. Results were analyzed on SPSS Statistics 21 using ANOVA with a p-value of ≤0.05 regarded as significant. Results: Hormonal analysis shows that cortisol levels in the vasovagal, postural tachycardia syndrome and in control group was 153±16.7pg/ml, 160.17±pg/ml, and 69.65±5.8pg/ml respectively. Cortisol levels were significantly higher in both vasovagal and POTS groups as compared to controls with a p-value of 0.04 and 0.023 respectively. However, there was no significant difference between vasovagal and POTS patients with p value 0.570. Conclusion: It is concluded from the study that cortisol responses of VVS and POTS were positive. doi: https://doi.org/10.12669/pjms.38.1.4122 How to cite this:Khan HF, Ambreen S, Raziq H, Hayat A. Comparison of cortisol levels in patients with vasovagal syncope and postural tachycardia syndrome. Pak J Med Sci. 2022;38(1):185-189. doi: https://doi.org/10.12669/pjms.38.1.4122 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

OBJECTIVE The sit-up test is used to assess orthostatic hypotension, without the use of a tilt table, in populations who are unable to stand. The primary objective of this study was to determine the differences in blood pressure and hemodynamic responses between the sit-up and head-up tilt tests. The secondary objective was to determine the hemodynamic responses related to changes in blood pressure during each test. METHODS Nineteen healthy volunteers (nine males, aged 24.3 ± 2.4 years) underwent the sit-up and head-up tilt tests. Systolic and diastolic blood pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance were measured. RESULTS The increase in systolic blood pressure (15 ± 9 vs. 8 ± 8 mmHg) was greater, while the increase in heart rate (8 ± 5 vs. 12 ± 8 bpm) and reduction in stroke volume (-17 ± 10 vs. -21 ± 10 ml) were smaller during the sit-up test than during the head-up tilt test (P < 0.05). Additionally, the increases in blood pressure variables were significantly associated with the increase in total peripheral resistance (P < 0.05), but not with changes in other hemodynamic variables in both tests. CONCLUSION Although the magnitudes of changes in systolic blood pressure, heart rate, and stroke volume differed between the tests, the hemodynamic variable related to changes in blood pressure was the same for both tests. These results may contribute to the clinical application of the sit-up test for identifying the presence and hemodynamic mechanisms of orthostatic hypotension.

Background/Introduction The neurohumoral profile underlying the manifestation of reflex syncope remains incompletely understood. Adenosine plasma (ADP) and adenosine receptor (ADR) levels may differentiate the outcomes of head-up tilt table test (HUTT) and adenosine test (ADT) but their role in the diagnostic evaluation of patients with syncope has yet to be determined. Purpose We sought to assess the ADP and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences in the outcomes of the HUTT and ADT tests as well as to the ADP levels during HUTT. Methods HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine 0.15 mg/kg administration in the supine position. ADP levels were assessed at three timepoints during the HUTT: at baseline (supine), immediately after bed tilt and, in cases of a positive HUTT, at the time of syncope. Patients were categorized in quintiles of very low, low, intermediate, high and very high baseline ADP levels. We also assessed the A2A ADR levels of monocytes. Results We prospectively analyzed 124 patients (71 women, age 46.78±21.01 years). ADT was positive in 12.9% of patients and HUTT in 44.4% of patients. Patients with very low baseline ADP levels (lowest quintile) more frequently presented with a positive ADT (odds ratio [OR] 4.08, 95% Confidence Interval [CI] 1.40 to 13.13, p20 min) had lower ADR levels (80.88±238.98 vs 89.43±96.08 MFI, p Conclusion(s) Baseline ADP levels are related to the outcome of ADT while an ADP increase immediately after bed tilt and in syncope is evident in vasodepressor response to HUTT. Higher ADR levels are related to positive ADT and negative HUTT. Lower ADR levels are associated with more delayed onset of syncope during HUTT. ADP and ADR levels warrant further investigation as they may characterize a subset of patients with specific responses to ADT and HUTT and may be implicated in the pathophysiology of reflex syncope. Funding Acknowledgement Type of funding sources: None.

The tilt table test was performed on 20 healthy individuals, who voluntarily participated in this study, out of which the data of 19 volunteers has been used to determine the gender related differences occurring in HRV because 1 volunteer was making movements and was continuously talking. The selected subjects were in the age ranging from 20 to 30 years and had a mean age of 23.894 ± 2.183 years. The subjects considered for this study were B.Tech and M.Tech students of NIT Jalandhar. The individuals considered in this study are all Indians belonging from different states. The tilt table test was performed at different angles of tilt which were 0°, 20°, 40°, 60°, 40°R, 20°R, and 0°R. The data was recorded in the biomedical instrumentation lab, NIT Jalandhar, which was later analyzed and assessments were drawn out between males and females. The study aimed to investigate the effect of gender on HRV using tilt table testing particularly head-up tilt and head-reverse tilt. The frequency-domain indices were calculated and comparison graphs were made to illustrate the changes occurring in HRV of men and women at different tilt angles. Frequency-domain analysis conveys how the energy of a signal is distributed over a range of frequencies. The tilt table was not brought back to 0° after every recording session at every angle, which means the angles were continuously increased after acquiring data for 7 min per specified degree tilt. The results convey that the sympathetic activity increases during head-up tilt and the parasympathetic activity takes over during head-reverse tilt. The outcome of this study demonstrates that healthy females in the age group of 20–30 years have sympathetic dominance at different angles of tilt, whereas healthy males of the same age group illustrate parasympathetic dominance at different tilt angles.

It was hypothesized that faster cardiorespiratory kinetics during exercise are associated with higher orthostatic tolerance. Cardiorespiratory kinetics of 14 healthy male subjects (30 ± 4 years, 179 ± 8 cm, 79 ± 8 kg) were tested on a cycle ergometer during exercise with changing work rates of 30 and 80 W. Pulmonary oxygen uptake ([Formula: see text]) was measured breath-by-breath and heart rate (HR), mean arterial blood pressure (MAP), and total peripheral resistance (TPR) were measured beat-to-beat. Muscular oxygen uptake ([Formula: see text]) was estimated from HR and [Formula: see text]. Kinetic parameters were determined by time-series analysis, using cross-correlation functions (CCFmax(x)) between the parameter and the work rate. Cardiovascular regulations of MAP, HR, and TPR during orthostatic stress were measured beat-to-beat on a tilt seat. Changes between the minima and maxima during the 6° head-down tilt and the 90° head-up tilt positions were calculated for each parameter (Δtilt-up). [Formula: see text] correlated significantly with ΔTPRtilt-up (r = 0.790, p ≤ 0.001). CCFmax(HR) was significantly correlated with ΔHRtilt-up (r = –0.705, p = 0.002) and the amplitude in HR from 30 to 80 W (rSP = –0.574, p = 0.016). The observed correlations between cardiorespiratory regulation in response to exercise and orthostatic stress during rest might allow for a more differential analysis of the underlying mechanisms of orthostatic intolerance in, for example, patient groups.

Conflicting results have been published considering the role of head-up tilt test (HUTT) positivity as a prognostic factor in patients with hypertrophic cardiomyopathy (HCM). The relationship between HCM patients' genotype and their HUTT results has not been previously reported.The aim of this study was to evaluate patients with HCM and their HUTT results in regard to its value for outcome prediction and to investigate the relation of patients' genotype and their HUTT results.Seventy-four (51 ± 15 years; 42% women; median follow-up 72 months) HCM patients were divided into two groups based on their HUTT results and were retrospectively analyzed. In 67 (90.5%) subjects included in the analysis, next-generation sequencing-based genomic testing was performed. A composite end point of unexplained syncope, heart failure hospitalization, and death was defined.A total of 14 patients (18.9%) had positive HUTT (HUTT+), whereas 60 (81.1%) had negative HUTT (HUTT–). Except for the New York Heart Association functional class (p = 0.01), both groups had similar characteristics. Positive genotype was evenly distributed between the two groups. Composite end point occurred in 5 patients (35.7%) in HUTT+ group versus 14 (23.3%) patients in HUTT– group (p = 0.33).We did not find a relationship between HUTT results and long-term outcome. We found no association between HUTT results and genotype.

Background Atrial fibrillation (AF) often progresses to more sustained forms and increases the risk of ischemic stroke or sinus node dysfunction. However, there have been no data on the clinical outcomes of patients who developed AF during head-up tilt testing (HUT). Objective The purpose of this study was to evaluate the clinical significance of AF detected during HUT performed for syncope evaluation. Methods We analyzed incidence, short- and long-term prognosis, and predictors of adverse outcomes of AF detected during HUT, which was performed in 6780 consecutive patients without AF history. Results Of the 6780 patients, 52 (0.8%) developed AF during passive tilting (n = 5), isoproterenol infusion (n = 32), and recovery phase (n = 15) of HUT, respectively. There was no short-term adverse event: spontaneous sinus conversion occurred in 43 patients (83%) within 48 hours. Over a median follow-up of 34.8 months, 24 patients (46%) had AF recurrence with initial presentation as ischemic stroke (n = 2), sinus node dysfunction requiring pacemaker (n = 10), and AF alone (n = 12). In addition, 19 of 24 recurred AF cases (79.2%) progressed to persistent/permanent forms. The index AF duration was identified as an independent predictor of AF recurrence. Patients with longer AF duration (≥1.0 hour) showed worse prognosis than did those with shorter AF duration ( Conclusion The incidence of AF during HUT was ∼0.8%, and short-term prognosis was favorable. However, about half of the cases were complicated by long-term adverse outcomes. Therefore, regular follow-up might be warranted for patients with HUT-induced AF, particularly when AF duration is long.

Baroreceptor function in children and adolescents has not been well studied in the current literature, with a lack of agreed upon normal values. The authors hypothesize that there is a significant increase in the baroreceptor activity with a decrease in the sensitivity during the upright phase in comparison to the supine phases of the head upright tilt test (HUTT) protocol. Baroreceptor evaluation was performed using the sequence method in 49 subjects ages 8–21 years, during the 3 phases of HUTT: supine, head up, and post-tilt supine positions. Baroreceptor Effectiveness Index (BEI) and the number and slope of baroreceptor events were recorded. On study of the events and slope values, there was a significant difference between the three phases of the HUTT with regard to the baroreceptor activity and sensitivity. No significant difference was found in BEI. Our study presents normal values of baroreceptor activity, sensitivity, and BEI in pediatric patients under controlled supine and head up position. We also present new data regarding delayed heart rate responses to pressure changes in the Lag 1 and Lag 2 parameters, which may be beneficial in diagnosis and management of pediatric patients with orthostatic intolerance.

Background Head Up Tilt-table Test (HUTT) is a practical examination of the most common type of pediatrics syncope. The electrocardiographic (ECG) changes during this test, show the autonomic defects that cause neuraly-mediated syncope in response to tilting process. Methods All pediatric syncope patients referred to our center in a one-year period, were included in the study. HUTT was performed and patients were classified into two groups of Negative and Positive HUTT results, and the latter group was subclassified as three subgroups of "vasodepressor", "cardioinhibitory" and "mixed type" responses to HUTT. QT and corrected QT (QTc) dispersion was measured by the baseline standard 12-lead ECG obtained before HUTT. Results Eighty-six patients with a mean age of 12.19±5.34 were included. Patients with positive HUTT were significantly younger and male gender was more prevalent in this group. Mean QT dispersion was significantly higher in patients with positive HUTT result and also in patients with mixed response to HUTT compared to isolated vasodepressor response. Duration of QTc interval did not change between different study groups. Reciever-Operating-Characteristic (ROC) analysis showed that QT dispersion higher than 32ms is a significant predictor of positive HUTT result (with 92% sensitivity and 98% specificity) and values higher than 40ms can predict the mixed type of response to HUTT (with 84% sensitivity and 63% specificity). Conclusions Baseline myocardial repolarization disparity significantly correlates with susceptibility to symptomatic vasovagal syncope. This pathology seems to play its role mainly via excessive vagotonic response to sympathetic activation during HUTT process (known as cardioinhibitory response). This article is protected by copyright. All rights reserved.

Background: Failure to activate autonomic neural and hormonal reflex mechanisms could result in orthostatic hypotension. Patients with orthostatic hypotension often experience symptoms of cerebral hypoperfusion, including syncope. The purpose of this study was to investigate the haemodynamic characteristics of patients with orthostatic hypotension and the factors affecting blood pressure regulation.Methods: This retrospective study enrolled 45 patients who were diagnosed with typical orthostatic hypotension by the head-up tilt test at Beijing Tiantan Hospital, Capital Medical University from June 2019 to December 2020. Changes in haemodynamic parameters in these patients were compared in the supine and tilted upright positions.Results: For all patients, haemodynamic parameters in the supine and tilted upright positions were compared, and systolic blood pressure, diastolic blood pressure, mean blood pressure, cardiac output and stroke volume were all significantly decreased per minute. Heart rate significantly increased per minute, but systemic vascular resistance did not significantly change. The absolute value, percentage and rate of increases in heart rate and the absolute value, percentage and rate of decreases in stroke volume from the supine to the titled upright position were significantly lower in patients 60 years and older than in patients under 60 years old. Linear regression analyses found that the changes in heart rate, stroke volume and systemic vascular resistance were related to changes in systolic blood pressure, while the changes in stroke volume and systemic vascular resistance had more important effects on systolic blood pressure.Conclusions: In patients with orthostatic hypotension, we observed no significant increase in systemic vascular resistance from the supine position to the tilted upright position. Nevertheless, an increase in systemic vascular resistance had a significant impact on the maintenance of systolic blood pressure. In addition, in orthostatic hypotension patients younger than 60 years of age, heart rate increased while stroke volume decreased significantly after tilting upright compared with orthostatic hypotension patients older than 60 years of age and older.

The purpose of this study is to assess the cardiovascular system response to orthostatic stress in a group of 133 healthy men using heart rate asymmetry (HRA) methods. HRA is a feature of variability in human heart rate which is dependent upon external and internal body conditions. The initial phases of head-up tilt test (HUTT), namely, supine and tilt, were chosen as the external body affecting factors. Various calculation methods of HRA, such as Porta’s index (PI), Guzik’s index (GI), and its variance based components, were used to assess the heart rate variability (HRV) and its asymmetry. We compared 5-min ECG recordings from both supine and tilt phases of HUT test. Short-term HRA was observed in 54.1% of men in supine phase and 65.4% of men in tilt phase. The study revealed significant increase of GI (from 0.50 to 0.52, p < 0.001) in the tilt phase as well as significant changes in HRV descriptors between HUTT phases. Our results showed that the variability of human heart rate and its asymmetry are sensitive to orthostatic stress. The study of short-term HRA is a potential additional tool to increase sensitivity in conditions where HUTT is a diagnostic tool, such as vasovagal syncope.

Background Kinocardiography (KCG) is a promising new technique used to monitor cardiac mechanical function remotely. KCG is based on ballistocardiography (BCG) and seismocardiography (SCG), and measures 12 degrees-of-freedom (DOF) of body motion produced by myocardial contraction and blood flow through the cardiac chambers and major vessels. Results The integral of kinetic energy ($$ iK$$ iK ) obtained from the linear and rotational SCG/BCG signals was computed over each dimension over the cardiac cycle, and used as a marker of cardiac mechanical function. We tested the hypotheses that KCG metrics can be acquired using different sensors, and at 50 Hz. We also tested the effect of record length on the ensemble average on which the metrics were computed. Twelve healthy males were tested in the supine, head-down tilt, and head-up tilt positions to expand the haemodynamic states on which the validation was performed. Conclusions KCG metrics computed on 50 Hz and 1 kHz SCG/BCG signals were very similar. Most of the metrics were highly similar when computed on different sensors, and with less than 5% of error when computed on record length longer than 60 s. These results suggest that KCG may be a robust and non-invasive method to monitor cardiac inotropic activity. Trial registration Clinicaltrials.gov, NCT03107351. Registered 11 April 2017, https://clinicaltrials.gov/ct2/show/NCT03107351?term=NCT03107351&draw=2&rank=1.

Background Orthostatic hypotension (OH) occurring almost immediately (i.e., immediate OH, iOH) after movement to standing position is common, and may cause collapse due to instability or syncope. However, while “classic” OH (cOH) which typically occurs later is well-studied, iOH has received less attention. Objectives This study was designed to better understand blood pressure (BP) alterations associated with iOH in normal subjects and in symptomatic patients (pts) and to compare findings with both Active standing and Head-up tilt (HUT). Methods We studied 118 patients comprising 4 groups: 1) Normals (n=38), 2) Vasovagal syncope (VVS: n=27), 3) cOH (n=37), and 4) Primary Autonomic Failure (PAF, n=16). We compared timing and magnitude of BP fall and recovery during both drug-free “active standing” (≤10 min) and HUT (70°, ≤20 min). Continuous ECG and beat-to-beat BP were recorded. Statistical significance was tested using paired-t test and ANOVA as appropriate (significance: p≤0.05). Results Sex and BMI were similar among groups, but PAF pts tended to be older (62±17 yrs) vs Normals (44±16 yrs), VVS (32±12) and OH (45±21 yrs) pts. Time from upright posture to BP nadir was shorter with active standing vs HUT [p Conclusion Active standing and HUT differ in evaluation of symptomatic pts. “Active standing” is associated with lesser time to BP nadir, greater BP fall, and faster BP recovery than with HUT. Additionally, iOH BP nadir typically occurs ≤15–20s after upright posture with rapid recovery necessitating beat-to-beat recordings to assess accurately. Funding Acknowledgement Type of funding source: None

Background/Introduction Head-up tilt table test (HUTT) and Adenosine test (ADT) can be useful in the diagnostic evaluation of syncope. Adenosine plasma (ADP) and Adenosine receptor (ADR) levels may differentiate the outcomes of HUTT and ADT but their precise role in the risk stratification of patients with syncope remains elusive. Purpose We sought to assess the ADP and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences in the outcomes of the HUTT and ADT tests as well as to the ADP levels during HUTT according to the baseline ADP levels. Methods HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine 0.15 mg/kg administration in the supine position. ADP levels (ppm/Um/L) were assessed at three timepoints during the HUTT: at baseline (supine), immediately after bed tilt and, in cases of a positive HUTT, at the time of syncope. Patients were categorized in terciles of low, intermediate and high baseline ADP levels. We also assessed the A2A ADR levels of monocytes. Results We prospectively analyzed 106 patients (62 women, age 46.87±20.63 years). ADT was positive in 14.2% of patients and HUTT in 47.2% of patients. Females were more likely to have low ADP levels (odds ratio [OR] 2.70, 95% Confidence Interval [CI] 1.04 to 6.94, p Conclusion(s) Baseline ADP levels may be related to the outcome of ADT and HUTT. ADP increases during HUTT except for patients with high baseline ADP. ADP and ADR levels warrant further investigation as they may characterize a subset of patients with specific responses to HUTT and may be implicated in the pathophysiology of reflex syncope. Funding Acknowledgement Type of funding source: None

A critical step in the clinical evaluation of postural tachycardia syndrome (PoTS) is the assessment of orthostatic tachycardia. Active stand testing (AST) and head up tilt table testing (HUT) can both be used to evaluate the presence of this tachycardia. Drugs that affect heart rate (HR), sympathetic nervous system activity, or blood volume should be withheld prior to the orthostatic test. There are several important methodological and physiological differences with HUT versus AST. Orthostatic heart rate is typically higher during HUT than with AST, and requires specialized equipment that is not available to all clinicians. Conversely, AST is convenient, cost-effective and can be performed in the primary care physician office. Reflex tachycardia specific to initial orthostatic hypotension may be greater in the initial minutes of AST, compared to HUT, and this should be considered in the evaluation of early AST HR responses. The AST has similar sensitivity and greater specificity than HUT. Overall, AST should be used as the first line diagnostic tool during assessment of orthostatic tachycardia in PoTS.

PPG can provide information on cardiovascular responses to fluid shifts from upper to lower part of body under the condition of orthostatic stress. The current study investigated ability of PPG derived LVET and other PPG derived features to identify progressive central hypovolemia induced by head up tilt (HUT) and evaluated potential use of LVET as early noninvasive indicator of blood loss. Continuous finger PPG, blood pressure, and electrocardiography were recorded simultaneously during 5-minutes of baseline and HUT of 20°, 40°, and 60° from 15 participants (age: 26.5 ± 3 years; height: 177 ± 8 cm; weight: 72 ± 10 kg, mean ± SD). Beat-by-beat pulse rate (PR), systolic amplitude (SA), systolic time (ST), diastolic time (DT), and PP Interval (PPI) and Ratio of pulse rate over systolic amplitude (PR/SA) were derived for each stage. LVET was derived from each stage. Friedman test followed by post-hoc analysis using Tukey-HSD was conducted to highlight the significance of changes induced by HUT. Application of 60° HUT (i.e. moderate category simulated hypovolemia) resulted in a significant change in PR (80±3 bpm vs 68±3 bpm, p=0.0008), DT (264±7 ms vs 303±4 ms, p=0.0008), ST (110±6 ms vs 117±7 ms, p=0.02), PP interval (764±39 ms vs 869±25 ms, p=0.0045), PR/SA (112±16 vs 82±21, p=0.012) , SA (0.875± 0.2 vs 1.69±0.6, p=0.012) and LVET(292 vs 351ms,p=0.0008) compared to baseline. LVET has a strong association with the change in central blood volume and may be used as a sensitive early marker of progressive hypovolemia. The findings of the study support the hypothesis of differentiating simulated hypovolemia based on PPG alone. Keywords: Hypovolemia, HUT, LVET.

Significance: Cerebral oxygenation changes in the superior, middle, and medial gyri were used to elucidate spatial impairments of autonomic hemodynamic recovery during the head-up tilt table test (HUTT) in Parkinson’s disease (PD) patients with orthostatic intolerance (OI) symptoms. Aim: To analyze dynamic oxygenation changes during the HUTT and classify PD patients with OI symptoms using clinical and oxygenation features. Approach: Thirty-nine PD patients with OI symptoms [10: orthostatic hypotension (PD-OH); 29: normal HUTT results (PD-NOR)] and seven healthy controls (HCs) were recruited. Prefrontal oxyhemoglobin (HbO) changes during the HUTT were reconstructed with diffuse optical tomography and segmented using the automated anatomical labeling system. Decision trees were used for classification. Results: HCs and PD-NOR patients with positive rates of HbO change (PD-POS) showed the greatest HbO recovery in the superior frontal gyrus (SFG) during tilt. PD-OH and PD-NOR patients with negative rates of HbO change (PD-NEG) showed asymmetric reoxygenation. The classification accuracy was 89.4% for PD-POS versus PD-NEG, 71% for PD-NOR versus PD-OH, and 55.8% for PD-POS versus PD-NEG versus PD-OH. The oxygenation features were more discriminative than the clinical features. Conclusions: PD-OH showed decreased right SFG function, which may be associated with impaired compensatory autonomic responses to orthostatic stress.

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.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).

Background: We have previously shown in a group of adolescents who are suffering from orthostatic intolerance (OI) and syncope that they exhibited impairment in autonomic function in supine position and greater loss of baroreflex sensitivity (BRS) and heart rate variability (HRV) measures upon head up tilt (HUT). They also had low vitamin D level that correlated with the severity of symptoms on tilt. In this pilot study we hypothesized that vitamin D supplementation to normal levels will improve the autonomic response to change in position. Methods: In a pilot group of eight female adolescents (mean age= 16.0 years) who are vitamin D deficient, head up tilt was done at baseline and after two months of vitamin D supplementation (2000-5000 IU daily based on baseline level). Heart rate, blood pressure, BRS measured as Sequence Up (parasympathetic) and Sequence down (sympathetic), HRV measured as SDNN and rMSSD, and sympathovagal balance (LF/HF ratio) were assessed both in supine and HUT positions. Results: As shown in the table, compared to baseline, vitamin D supplementation improved vitamin D level, minutes standing on tilt, BRS, HRV and sympathovagal balance measures at baseline and reduced the loss in BRS and HRV measures upon standing. There were no changes in blood pressure measures between pre and post treatment. Conclusions: Vitamin D supplementation for two months restored vitamin D to normal levels and was associated with improvement in the hemodynamic response to standing. These data provide evidence of potential therapeutic benefit of vitamin D supplementation for patients suffering from orthostatic intolerance who are vitamin D deficient

We sought to determine whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation. Accordingly, nine young healthy men were studied while supine (0°) and during mild changes in hydrostatic pressure induced by head-up tilt at +20° and +10° (HUT+20 and HUT+10) and head-down tilt at -20° and -10° (HDT-20, HDT-10). Blood flows were measured in the internal and external carotid and vertebral arteries (ICA, ECA, and VA). Intraocular pressure (IOP) was measured as an indicator of hydrostatic changes in intracranial pressure. A posture change from HUT+20 to HDT-20 increased IOP by +5.1 ± 1.9 mmHg (

A 65-year-old woman, during an elective head up tilt test, after the sublingual nitrate administration, experienced electrocardiogram alteration with ST elevation in the inferior leads, that returned normal when the patient was laid supine after few minutes. Serial cardiac markers were not elevated and coronary angiography revealed normal epicardial coronary arteries. Paradoxical vasospastic response to nitrates in vasospastic angina patients represents a rare but very challenging condition and the best therapeutic approach in this subgroup of patients remains unclear.

(1) Background: The features characterizing vasovagal syncope (VVS) are an important factor in the correct evaluation of diagnostic risk stratification in children and adolescents. The aim of the study was to determine the value of identifying the clinical characteristics in children with VVS. (2) Methods: We made a retrospective analysis of the medical records of 109 children with diagnosed VVS. We investigated the specific characteristics of syncope in children with VVS including the positive VVS (+) and negative VVS (&minus, ) result of the Head-Up Tilt Table Test (HUTT). (3) Results: We did not observe significant differences in the prodromal symptoms of VVS with HUTT response. In addition to typical prodromal symptoms, no difference in statistically reported palpitations (35/109 or 32.1%) and chest discomfort (27/109 or 27.7%) were recorded. Fear&ndash, pain&ndash, stress emotions as circumstances of syncope were more often reported by children with a negative HUTT (p = 0.02). Cramps&ndash, contractures (p = 0.016) and speech disorders (p = 0.038) were significantly higher in the group with negative HUTT. (4) Conclusions: There is a close relationship in the diagnostic profile between the negative and positive results of head-up tilt table test in children with vasovagal syncope.

Introduction:Postural tachycardia syndrome (POTS) is a suspected dysautonomia with symptoms of orthostatic intolerance and abnormally increased heart rate while standing. We aimed to study cardiac autonomic nervous system functioning in head-up tilt (HUT) in adolescents with POTS to find out if parasympathetic tone is attenuated in the upright position. Methods:We compared characteristics of a group of 25 (females 14/25; 56%) adolescents with POTS and 12 (females 4/12; 34%) without POTS aged 9-17 years. We compared heart rate variability with high- and low-frequency oscillations, and their temporal changes in HUT. Results:The high-frequency oscillations, i.e., HF, attenuated in both groups during HUT (p

Nonhuman primates are often used in biomedical research and to investigate physiologic processes that occur in man. Impedance plethysmography was used to measure calf, thigh, pelvic, abdominal, and thoracic volume changes in ten Rhesus and eight squirrel monkeys during five-minute exposures to HUT and HDT at angles of 5, 10, and 20 degrees. Calf, rump and tail measurements were made in three squirrel monkeys at 10 and 20 degrees of HUT and HDT. Fluid volume changes in all segments of the Rhesus monkeys were found to change during HUT an HDT in direct relation to the angle of tilt used. However, the volume changes that occurred in the squirrel monkeys were found to be quite different. Their calf, thigh, and pelvic segments lost volume during both HUT and HDT while their abdominal and thoracic segments responded similarly to those of the Rhesus monkeys. These results and those of the calf/tail measurements of the squirrel monkeys suggest that they may utilize their tails as a compensatory reservoir during postural changes and therefore, may not be an appropriate animal model for man under some orthostatic test conditions.

Phenylephrine is an α-adrenergic agent and yet seems to increase near-infrared spectroscopy determined muscle oxygenation (SmO2) that reflects the ratio between oxygenated (O2Hb) and deoxygenated (...

Simple Summary Syncope is a medical condition triggered by short-lived interruption of the oxygen supply to the brain, which may result in free fall or accidents. The diagnosis of syncope is a challenging task, as various other states of altered consciousness present with the same symptoms as syncope. This work uses historical medical data for the diagnosis of syncope using sophisticated computing solutions. The experimental results prove the effectiveness of the approach, leading to the proactive prediction of syncope. Abstract Syncope is the medical condition of loss of consciousness triggered by the momentary cessation of blood flow to the brain. Machine learning techniques have been established to be very effective way to address such problems, where a class label is predicted for given input data. This work presents a Support Vector Machine (SVM) based classification of neuro-mediated syncope evaluated using train–test–split and K-fold cross-validation methods using the patient’s physiological data collected through the Head-up Tilt Test in pure clinical settings. The performance of the model has been analyzed over standard statistical performance indices. The experimental results prove the effectiveness of using SVM-based classification for the proactive diagnosis of syncope.

Broad complex tachycardia (BCT) during head up tilt test (HUTT) is infrequent. Electrophysiology Study (EPS) plays an important part in further differentiation of BCT. We present a case of BCT during HUTT in a patient presenting with presyncope which later on EPS with 3D mapping was diagnosed as ventricular tachycardia. This case highlights the unusual occurrence of BCT during HUTT, the differential diagnosis of BCT and the utility of EPS to reliably identify the type and origin of BCT.