Low iron storage and mild anemia in postural tachycardia syndrome in adolescents

Effect of lower body negative pressure on cardiac and cerebral function in postural orthostatic tachycardia syndrome: A pilot MRI assessment

Postural orthostatic tachycardia syndrome (POTS) is characterized by an excessive heart rate (HR) response upon standing and symptoms indicative of inadequate cerebral perfusion. We tested the hypothesis that during lower body negative pressure (LBNP), individuals with POTS would have larger decreases in cardiac and cerebrovascular function measured using magnetic resonance (MR) imaging. Eleven patients with POTS and 10 healthy controls were studied at rest and during 20 min of -25 mmHg LBNP. Biventricular volumes, stroke volume (SV), cardiac output (Qc), and HR were determined by cardiac MR. Cerebral oxygen uptake (VO2 ) in the superior sagittal sinus was calculated from cerebral blood flow (CBF; MR phase contrast), venous O2 saturation (SvO2 ; susceptometry-based oximetry), and arterial O2 saturation (pulse oximeter). Regional cerebral perfusion was determined using arterial spin labelling. HR increased in response to LBNP (p < 0.001) with no group differences (HC: +9 ± 8 bpm; POTS: +13 ± 11 bpm; p = 0.35). Biventricular volumes, SV, and Qc decreased during LBNP (p < 0.001). CBF and SvO2 decreased with LBNP (p = 0.01 and 0.03, respectively) but not cerebral VO2 (effect of LBNP: p = 0.28; HC: -0.2 ± 3.7 mL/min; POTS: +1.1 ± 2.0 mL/min; p = 0.33 between groups). Regional cerebral perfusion decreased during LBNP (p < 0.001) but was not different between groups. These data suggest patients with POTS have preserved cardiac and cerebrovascular function.

Novel pharmacotherapeutic options for the treatment of postural orthostatic tachycardia syndrome

INTRODUCTION

Postural tachycardia syndrome (POTS) is a disorder characterized by a constellation of symptoms including lightheadedness, fatigue, and palpitations when upright, associated with an increase in the heart rate (HR) of > 30 beats per minute when changing from a lying down to standing position or head-up tilt position and not associated with orthostatic hypotension. The causes as well as the management of POTS are not quite fully understood.

AREAS COVERED

We performed a literature review on the diagnosis and management of POTS, and this article includes an overview of novel pharmacotherapeutic options for the treatment of (POTS), although an effective treatment has not been established.

EXPERT OPINION

POTS is a clinical syndrome characterized by a constellation of symptoms that are nonspecific. No single etiology or unified hypothesis could be identified. In fact, multiple pathophysiological mechanisms have been proposed, and none of the suggested medications have been approved by the FDA for this indication. Further understanding of the autonomic nervous system and its adjustment to standing position is needed to provide better management strategies.

Neurocognitive Profiles in Adolescents With Postural Tachycardia Syndrome and Perceived Brain Fog: A Preliminary Report

BACKGROUND

Postural tachycardia syndrome (POTS) is associated with complaints of cognitive and emotional difficulties that may contribute to severe functional disability. For high-achieving adolescents, these symptoms can result in decreased participation in school and extracurricular activities. There are very limited data comparing subjective symptom reports to neurocognitive profiles in adolescents presenting with POTS, "brain fog," and cognitive difficulties.

METHODS

A review of medical records and neuropsychological data was conducted for six adolescents diagnosed with POTS at a pediatric neurology clinic. All patients had frequent symptoms of orthostatic intolerance for more than three months. There was heart rate increase of ≥40 beats per minute (bpm) within 10 minutes of active standing or head-up tilt test in five patients and 36 bpm in one patient, who was diagnosed with probable POTS. All were referred for neuropsychological evaluations due to reported debilitating cognitive problems and an inability to function in a regular academic setting. Patients underwent a six-hour neuropsychological evaluation utilizing standardized measures of cognitive and emotional functioning. Clinically reported symptoms included fatigue, poor concentration, and memory impairment as well as "brain fog."

RESULTS

Subjective complaints differed from patients' performance on standardized neuropsychological measures. Patients performed in the average to superior range across measures of general intelligence, verbal and working memory, processing speed, and sustained attention.

CONCLUSIONS

Further research is needed to elucidate the basis for perceived "brain fog" and cognitive impairment in POTS, such as better understanding of patient and parental perceptions of initial medical symptoms and diagnosis as well as symptom amplification due to biopsychosocial processes.

Postural orthostatic tachycardia syndrome-like symptoms following COVID-19 vaccination: An overview of clinical literature

BACKGROUND

Postural Orthostatic Tachycardia Syndrome (POTS) is a common condition affecting more than 170 people per 100,000 population. However, POTS following COVID-19 vaccination remains a rare reporting in the medical literature.

OBJECTIVE

We, herein, summarize and highlight the evidence that has been reported regarding POTS-like symptoms following COVID-19 vaccination.

METHODS

We conducted a literature search and summarized the findings in the form of a narrative commentary. All types of publications (case reports/series, original articles, letters to editors, brief communications etc.) in English language were included.

RESULTS

Whilst the exact pathogenetic mechanism behind POTS is yet to elucidated, there has been increasing evidence pointing towards an autoimmune dysfunction. Females were found to be predominantly affected (72%) with age range from 17 years to 52 years. Additionally, it seems that POTS-like symptoms could be triggered after immunization with Pfizer- BioNTech, Moderna, and Oxford-AstraZeneca COVID-19 vaccines. The symptoms typically appear within the first week, depending upon previous exposure to the virus and presence of other systemic conditions. In some patients, the condition is self-resolving. However, in others, non-pharmacological interventions coupled with negative ionotropic medications can be used for symptomatic management of the patients.

CONCLUSIONS

Timely diagnosis and proper treatment are quintessential for ensuring early alleviation (and in some cases complete resolution) of symptoms. Furthermore, there may be episodes of relapse. Overall prognosis of the new-onset POTS-like symptoms is difficult to predict based on current literature.

Biomarkers and Hemodynamic Parameters in the Diagnosis and Treatment of Children with Postural Tachycardia Syndrome and Vasovagal Syncope

In children, vasovagal syncope and postural tachycardia syndrome constitute the major types of orthostatic intolerance. The clinical characteristics of postural tachycardia syndrome and vasovagal syncope are similar but their treatments differ. Therefore, their differential diagnosis is important to guide the correct treatment. Therapeutic methods vary in patients with the same diagnosis because of different pathomechanisms. Hence, in patients with vasovagal syncope or postural tachycardia syndrome, routine treatments have an unsatisfactory efficacy. However, biomarkers could increase the therapeutic efficacy significantly, allowing for an accurate and detailed assessment of patients and leading to improved therapeutic effects. In the present review, we aimed to summarize the current state of research into biomarkers for distinguishing the diagnosis of pediatric vasovagal syncope from that of postural tachycardia syndrome. We also discuss the biomarkers that predict treatment outcomes during personalized therapy for each subtype.

Restless legs syndrome is increased in postural orthostatic tachycardia syndrome

STUDY OBJECTIVES

Postural orthostatic tachycardia syndrome (POTS) and restless legs syndrome (RLS) are both characterized by sleep disturbance along with autoimmune/inflammatory features and autonomic dysfunction. However, to our knowledge, there has been no direct study looking at the prevalence of RLS in patients with POTS patients compared with healthy participants (controls).

METHODS

Ninety-six physician-diagnosed patients with POTS (89 female and 7 male) and 130 controls (99 female and 31 male) were administered the Cambridge Hopkins questionnaire. Participants who were diagnosed with probable or definite RLS on the Cambridge Hopkins questionnaire were then contacted to determine the severity of RLS with the International Restless Legs Scale.

RESULTS

More patients with POTS (15 of 96; 15.6%) than controls (6 of 130; 4.6%) were diagnosed with probable or definite RLS on the Cambridge Hopkins questionnaire (P = .0048). A sensitivity analysis with only female respondents yielded similar results. RLS severity was in the moderate range (12.23 ± 9.22).

CONCLUSIONS

There is a higher prevalence of RLS in patients with POTS patients compared with controls. This association may have to do with shared increased inflammatory/autoimmune load and autonomic dysfunction.

Risk Factors for Orthostatic Hypertension in Children

OBJECTIVE

To investigate the risk factors for orthostatic hypertension in children.

STUDY DESIGN

Eighty children with orthostatic hypertension were enrolled in the group with orthostatic hypertension, and 51 healthy children served as the control group. Demographic characteristics, clinical history, daily water intake, nightly sleep duration, the results of the standing test, and complete blood count were recorded and compared between the 2 groups. The risk factors for pediatric orthostatic hypertension were determined by logistic regression analysis.

RESULTS

Body mass index and red blood cell distribution width were higher in the group with orthostatic hypertension than in healthy children, whereas daily water intake and sleep duration were lower. Logistic regression analyses showed that, if a child suffered from overweight, suffered from obesity, had a daily water intake of less than 800 mL, or had a red blood cell distribution width that was increased by 1%, the risk of orthostatic hypertension would be increased by 6.069 times (95% CI, 1.375-26.783; P < .05), 7.482 times (95% CI, 1.835-30.515; P < .01), 4.027 times (95% CI, 1.443-11.241; P < .01), or 4.008 times (95% CI, 1.698-9.461; P < .01), respectively. However, if the sleep duration was increased by 1 hour, the risk of developing orthostatic hypertension would be decreased by 74.3% (95% CI, 54.6%-85.4%, P < .01).

CONCLUSIONS

Increased body mass index, inadequate water intake and sleep duration, and elevated red blood cell distribution width were identified as risk factors for pediatric orthostatic hypertension.

Postural Tachycardia Syndrome in Children and Adolescents: Pathophysiology and Clinical Management

Postural tachycardia syndrome (POTS), characterized by chronic (≥6 months) orthostatic intolerance symptoms with a sustained and excessive heart rate increase while standing without postural hypotension, is common in children and adolescents. Despite the unclear pathogenesis of POTS, the present opinion is that POTS is a heterogeneous and multifactorial disorder that includes altered central blood volume, abnormal autonomic reflexes, "hyperadrenergic" status, damaged skeletal muscle pump activity, abnormal local vascular tension and vasoactive factor release, mast cell activation, iron insufficiency, and autoimmune dysfunction. A number of pediatric POTS patients are affected by more than one of these pathophysiological mechanisms. Therefore, individualized treatment strategies are initiated in the management of POTS, including basal non-pharmacological approaches (e.g., health education, the avoidance of triggers, exercise, or supplementation with water and salt) and special pharmacological therapies (e.g., oral rehydration salts, midodrine hydrochloride, and metoprolol). As such, the recent progress in the pathogenesis, management strategies, and therapeutic response predictors of pediatric POTS are reviewed here.

Pediatric-Onset Postural Orthostatic Tachycardia Syndrome in a Single Tertiary Care Center

AIM

We characterize the pediatric postural orthostatic tachycardia syndrome (POTS) population seen at a single tertiary care referral center.

METHOD

Retrospective chart review of all pediatric POTS patients seen in our center between 2015 and 2017. Pediatric POTS was defined as chronic, at least 3 months, symptoms of orthostatic intolerance associated with excessive orthostatic tachycardia as determined by tilt table testing with orthostatic heart rate increment of ≥40 bpm within 5 minutes of head-up tilt or absolute orthostatic heart rate ≥130 bpm for patients 13 years old and younger and ≥120 bpm for those 14 years and older. We looked at demographics, presenting symptoms, comorbidities, examination findings, investigation findings, treatment, and patient reported outcomes. Outcome measures were separated by patient report and group comparisons were made using 2-sample t tests or Mann-Whitney U tests for continuous variables and Fisher exact tests for categorical variables.

RESULTS

One hundred thirty-four patients with pediatric onset POTS were identified. The mean age was 15 years. Seventy-nine percent of patients were female and 90% were white. The most common presenting symptoms included dizziness/lightheadedness (88%), syncope (54%), and palpitations (40%). Many patients had significant comorbidities attributable to numerous bodily systems, most commonly headache syndromes (migraine 43%, nonspecific headache 22%, chronic daily headache 14%, and new daily persistent headache 5%) and chronic fatigue (60%). Low vitamin D and insufficient iron stores were commonly seen. The majority of patients improved or had resolution of symptoms following treatment (70%). When separated by outcome, statistically significant differences were found for glucose (patients whose symptoms resolved had higher median glucose), palpitations (patients whose symptoms resolved were less likely to have palpitations), constipation (patients whose symptoms were stable/worsened were more likely to have constipation), and unexplained pain (patients whose symptoms were stable/worsened were more likely to have unexplained pain).

CONCLUSIONS

Pediatric POTS is a chronic condition with a fairly good prognosis following appropriate treatment. It is associated with numerous comorbidities that necessitate multidisciplinary expert care.

Update of Individualized Treatment Strategies for Postural Orthostatic Tachycardia Syndrome in Children

Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous disease that predominantly affects children and adolescents. There is a great difference between children and adults in the diagnosis and treatment of POTS patients. POTS in children and adolescents is marked by chronic symptoms of orthostatic intolerance with a heart rate (HR) rise of ≥40 bpm, or heart rate exceeding 130 bpm for 6-12-years-old children and exceeding 125 bpm for those 13-18 years old without orthostatic hypotension, which is different from adult patients. The three major clinical forms of POTS include hypovolemic POTS, neuropathic POTS, and hyperadrenergic POTS; these are distinguished by their major mechanisms. The different subtypes of POTS in children and adolescents each have their own clinical characteristics and biomarkers. Based on these, we propose individualized treatment strategies. Individualized management strategies based on different subtypes of POTS would largely improve the curative effects of drugs for children with POTS. However, a further clinical investigation is still required to better understand the pathophysiology and treatment options.

Proteomic analysis reveals sex-specific biomarker signature in postural orthostatic tachycardia syndrome

Background

Postural orthostatic tachycardia syndrome (POTS) is a variant of cardiovascular (CV) autonomic disorder of unknown etiology characterized by an excessive heart rate increase on standing and orthostatic intolerance. In this study we sought to identify novel CV biomarkers potentially implicated in POTS pathophysiology.

Methods

We conducted a nested case-control study within the Syncope Study of Unselected Population in Malmö (SYSTEMA) cohort including 396 patients (age range, 15–50 years) with either POTS (n = 113) or normal hemodynamic response during passive head-up-tilt test (n = 283). We used a targeted approach to explore changes in cardiovascular proteomics associated with POTS through a sequential two-stage process including supervised principal component analysis and univariate ANOVA with Bonferroni correction.

Results

POTS patients were younger (26 vs. 31 years; p < 0.001) and had lower BMI than controls. The discovery algorithm identified growth hormone (GH) and myoglobin (MB) as the most specific biomarker fingerprint for POTS. Plasma level of GH was higher (9.37 vs 8.37 of normalised protein expression units (NPX); p = 0.002), whereas MB was lower (4.86 vs 5.14 NPX; p = 0.002) in POTS compared with controls. In multivariate regression analysis, adjusted for age and BMI, and stratified by sex, lower MB level in men and higher GH level in women remained independently associated with POTS.

Conclusions

Cardiovascular proteomics analysis revealed sex-specific biomarker signature in POTS featured by higher plasma level of GH in women and lower plasma level of MB in men. These findings point to sex-specific immune-neuroendocrine dysregulation and deconditioning as potentially key pathophysiological traits underlying POTS.

Pubertal Hormonal Changes and the Autonomic Nervous System: Potential Role in Pediatric Orthostatic Intolerance

Puberty is initiated by hormonal changes in the adolescent body that trigger physical and behavioral changes to reach adult maturation. As these changes occur, some adolescents experience concerning pubertal symptoms that are associated with dysfunction of the autonomic nervous system (ANS). Vasovagal syncope (VVS) and Postural Orthostatic Tachycardia Syndrome (POTS) are common disorders of the ANS associated with puberty that are related to orthostatic intolerance and share similar symptoms. Compared to young males, young females have decreased orthostatic tolerance and a higher incidence of VVS and POTS. As puberty is linked to changes in specific sex and non-sex hormones, and hormonal therapy sometimes improves orthostatic symptoms in female VVS patients, it is possible that pubertal hormones play a role in the increased susceptibility of young females to autonomic dysfunction. The purpose of this paper is to review the key hormonal changes associated with female puberty, their effects on the ANS, and their potential role in predisposing some adolescent females to cardiovascular autonomic dysfunctions such as VVS and POTS. Increases in pubertal hormones such as estrogen, thyroid hormones, growth hormone, insulin, and insulin-like growth factor-1 promote vasodilatation and decrease blood volume. This may be exacerbated by higher levels of progesterone, which suppresses catecholamine secretion and sympathetic outflow. Abnormal heart rate increases in POTS patients may be exacerbated by pubertal increases in leptin, insulin, and thyroid hormones acting to increase sympathetic nervous system activity and/or catecholamine levels. Given the coincidental timing of female pubertal hormone surges and adolescent onset of VVS and POTS in young women, coupled with the known roles of these hormones in modulating cardiovascular homeostasis, it is likely that female pubertal hormones play a role in predisposing females to VVS and POTS during puberty. Further research is necessary to confirm the effects of female pubertal hormones on autonomic function, and their role in pubertal autonomic disorders such as VVS and POTS, in order to inform the treatment and management of these debilitating disorders.

How I approach iron deficiency with and without anemia

Iron deficiency anemia remains a common referral to the pediatric hematology-oncology subspecialist. Improved understanding of iron homeostasis, including the effects of the regulatory hormone hepcidin, recent adult and pediatric clinical trial data, as well as the availability of safer formulations of intravenous iron, have resulted in additional considerations when making treatment recommendations in such patients. Young children and adolescent females remain the most commonly affected groups, but children with complex medical or chronic inflammatory conditions including comorbid gastrointestinal disorders also require special consideration.

Hemocytometric Measures Predict the Efficacy of Oral Rehydration for Children with Postural Tachycardia Syndrome

OBJECTIVE

To explore whether hemocytometric measures could be qualified predictors for the effect of oral rehydration salts (ORS) in children with postural tachycardia syndrome (POTS).

STUDY DESIGN

Thirty-five children with POTS and 29 healthy children were enrolled. General information, hemodynamic status, and baseline hemocytometric variables were collected. Children with POTS received ORS therapy and were followed up for 3 months. The independent risk factors of developing POTS were explored. A receiver-operating characteristic curve was used to evaluate predictive value of hemocytometric variables for therapeutic effectiveness of ORS therapy.

RESULTS

Children with POTS had larger mean corpuscular volume (MCV) and lower mean corpuscular hemoglobin concentration (MCHC) values than controls (P < .05). The baseline MCV values positively correlated with heart rate elevation from supine to upright (r = 0.294, P < .05). Both larger MCV and lower MCHC values were independent risk factors of developing POTS (for MCV, P < .05, OR 1.222; for MCHC, P < .05, OR 0.936). In children with POTS, responders to ORS had baseline lower MCV and higher MCHC than nonresponders (P < .05). The receiver-operating characteristic curve for the predictive value of MCHC showed that area under the curve was 0.73.

CONCLUSIONS

MCHC values could be used to predict the effectiveness of ORS for treating POTS in children.

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.