Orthostatic intolerance in adults with long COVID was not associated with postural orthostatic tachycardia syndrome

In this observational cross-sectional study, we investigated predictors of orthostatic intolerance (OI) in adults with long COVID. Participants underwent a 3-minute active stand (AS) with Finapres NOVA, followed by a 10-minute unmedicated 70-degree head-up tilt test. 85 participants were included (mean age 46 years, range 25-78; 74% women), of which 56 (66%) reported OI during AS (OIAS). OIAS seemed associated with female sex, more fatigue and depressive symptoms, and greater inability to perform activities of daily living (ADL), as well as a higher heart rate (HR) at the lowest systolic blood pressure (SBP) point before the 1st minute post-stand (mean HRnadir: 88 vs 75 bpm, P=0.004). In a regression model also including age, sex, fatigue, depression, ADL inability, and peak HR after the nadir SBP, HRnadir was the only OIAS predictor (OR=1.09, 95% CI: 1.01-1.18, P=0.027). 22 participants had initial (iOH) and 5 classical (cOH) orthostatic hypotension, but neither correlated with OIAS. 71 participants proceeded to tilt, of which 28 had OI during tilt (OItilt). Of the 53 who had a 10-minute tilt, 7 (13%) fulfilled hemodynamic postural orthostatic tachycardia syndrome (POTS) criteria, but 6 did not report OItilt. OIAS was associated with a higher initial HR on AS, which after 1 minute equalized with the non-OIAS group. Despite these initial orthostatic HR differences, POTS was infrequent and largely asymptomatic. ClinicalTrials.gov Identifier: NCT05027724 (retrospectively registered on August 30, 2021).

Prognostic Value of Biomarkers in Children and Adolescents With Orthostatic Intolerance

Orthostatic intolerance (OI) refers to a series of symptoms that occur during upright standing, which can be relieved when returned to the supine position. OI is a common cause of syncope in children and adolescents. In recent years, more and more studies have been carried out to assess the prognosis of OI by using biomarkers, among which, flow-mediated vasodilation, left ventricular ejection fraction and fractional shortening, hemodynamic change during head-up tilt test, detection of 24-h urinary sodium excretion, body mass index, midregional pro-adrenomedullin, and erythrocytic H2S producing rate are relatively stable, inexpensive, and easy to obtain. With the help of biomarkers, individualized treatment can be carried out to improve the long-term prognosis of children and adolescents with OI. This article reviews the prognostic value of biomarkers in children and adolescents with OI.

Support Vector Machine-Based Classification of Vasovagal Syncope Using Head-Up Tilt Test

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.

Interesting presentation of a broad complex tachycardia during the head up tilt table test

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.

Comparison of the Active Sitting Test and Head-Up Tilt Test for Diagnosis of Postural Tachycardia Syndrome in Children and Adolescents

Objectives: We aimed to compare the hemodynamic responses to the active sitting test with the passive head-up tilt test (HUTT) in children and adolescents with postural tachycardia syndrome (POTS). We hypothesized that sitting tachycardia was also present in POTS patients during sitting.Materials and methods: We tested 30 POTS patients and 31 control subjects (mean age = 12 years, range = 9–16 years) who underwent both active sitting test and HUTT successively. We measured the heart rate (HR) and blood pressure (BP) during each test.Results: For both POTS patients and control subjects, the HUTT produced significantly larger HR and BP increases from 3 to 10 min of postural change than did the sitting test. Moreover, POTS patients with excessive orthostatic tachycardia during the HUTT also had significantly larger increases in HR at all test intervals during the sitting test than did the control subjects. A maximum increase in HR ≥ 22 bpm within 10 min of the sitting test was likely suggested to predict orthostatic tachycardia, yielding a sensitivity and specificity of 83.3 and 83.9%, respectively. Only six of 30 POTS patients (20%) reached the 40-bpm criterion during the sitting test, and no one complained of sitting intolerance symptoms.Conclusions: We have shown that POTS patients also have sitting tachycardia when changing from a supine position to a sitting position. We believe that the active sitting test is a reasonable alternative maneuver in assessing POTS in population groups that cannot tolerate the standing test or HUTT.

Clinical Significance of the Head-Up Tilt Test in Improving Prognosis in Patients with Possible Neurally Mediated Syncope

Syncope is commonly encountered in daily clinical practice. Depending on its etiology (benign or life-threatening conditions or environmental triggers), syncope can be neurally mediated (reflex), cardiac, or orthostatic. Furthermore, neurologic disease can cause symptoms that mimic syncope. However, there is limited research on neurally mediated syncope (NMS), which is considered a benign disorder, and close follow-ups are rarely performed. NMS can cause serious clinical events, including severe trauma and car accidents. The head-up tilt test (HUTT) is the gold standard for diagnosing NMS; however, its clinical significance remains unknown, and its relevance to NMS prognosis requires further research. This retrospective study aimed to assess the clinical significance of the HUTT for NMS. We reviewed the charts of 101 patients who underwent HUTT at Tokai University Hospital in Japan between January 2016 and March 2019. During the HUTT, 72 patients (69.2%) experienced syncope. Patients were followed up for 886.1 ± 457.7 days (interquartile range: 518–1293 days). The syncope recurrence rate was 16.9%; however, no significant difference was observed between the two groups (HUTT positive vs. negative) (13.8% vs. 18.1%, p = 0.772). Four of 29 (13.9%) and two of 72 (2.8%) patients in the negative and positive HUTT groups, respectively, experienced cardiac events (p = 0.019). Negative HUTT results may assist in anticipating unexpected clinical events within a few years. A negative HUTT result may allow us to reconsider the NMS diagnosis based on clinical information. Close outpatient follow-up of patients with negative HUTT results is warranted.

Personalized Simulated HUT as an At-home Prediction Model for Heart Rate Changes in Syncope Patients and At-home, Orthostatic Self-training Efficacy

Head-up tilt (HUT) testing supports the diagnosis of syncope by detecting abnormalities in heart rate and blood pressure changes. Home-based self-training can be of benefit to neurocardiogenic patients if during clinical HUT, heart rate decreases in the early stage of being in an upright position. However, HUT testing is not always possible in the hospital as it is inconvenient and sometimes even risky for patients with cardiac abnormalities as it may trigger a loss of consciousness and arrhythmia. To address this, the current paper introduces a personalized HUT simulation to determine the efficacy of at-home training. To develop the model, Holter ECG recordings were obtained from 28 syncope patients and the simulated output was compared to clinical findings. The model aims to predict heart rate changes associated with the simulated HUT that can indicate efficacy of an at-home program. Heart rate represents a variable of velocity in the model measured in liters per second against gravity. The results show that a decrease in heart rate in early simulated HUT as determined by the model shows a greater than 84% efficiency for syncope patients to benefit from at-home training and allows physicians to recommend home training during an online or telemedicine consultation. Keywords— head-up tilt test, syncope, blood flow, heart rate prediction Clinical Relevance— The cardiovascular model predicts the patient-specific efficacy of at home tilt-training for patients diagnosed with syncope.