Evaluation of postural tachycardia syndrome (POTS)

The use and effectiveness of exercise for managing postural orthostatic tachycardia syndrome in young adults with joint hypermobility and related conditions: A scoping review

PURPOSE

Postural Orthostatic Tachycardia Syndrome (POTS) is a form of dysautonomia. It may occur in isolation, but frequently co-exists in individuals with hypermobile variants of Ehlers-Danlos Syndrome (EDS) and related conditions (chronic fatigue syndrome [CFS] and fibromyalgia). Exercise is recommended for non-pharmacological POTS management but needs to be individualised. This scoping review explores the current literature on use and effectiveness of exercise-based management for POTS, with specific focus on individuals with joint hypermobility and related conditions who experience hypermobility, and/or pain, and/or fatigue.

METHODS

A systematic search, to January 2023, of Medline, EMBASE, AMED, CINAHL and the Cochrane library was conducted. Studies that reported on adolescents and adults who had been diagnosed with POTS using standard criteria and underwent an exercise-based training intervention were included.

RESULTS

Following full-text screening, 10 articles were identified (2 randomised control trials, 4 comparative studies and 4 case reports). One comparative study reported a small subset of participants with EDS and one case report included an individual diagnosed with CFS; the remainder investigated a wider POTS population. Overall, 3 months of endurance followed by resistance exercise, graduating from the horizontal-to-upright position reduced POTS symptoms and improved quality-of-life.

CONCLUSION

The findings highlight a paucity of higher-level studies documenting exercise for POTS management in people with joint hypermobility and related conditions. Results from the wider POTS population demonstrate exercise is safe and effective. Large, well-designed clinical studies exploring exercise for POTS management adapting to meet the complex musculoskeletal and non-musculoskeletal features of symptomatic joint hypermobility are needed.

Dysautonomia, Hypermobility Spectrum Disorders and Mast Cell Activation Syndrome as Migraine Comorbidities

PURPOSE OF REVIEW

Dysautonomia refers to the dysfunction of the autonomic nervous system and encompasses a wide variety of autonomic symptoms and disorders. The most common autonomic disorders are postural orthostatic tachycardia syndrome (POTS), neurocardiogenic syncope (NCS), and orthostatic hypotension (OH), which may be encountered in clinical practice as part of a triad of dysautonomia, hypermobility spectrum disorders (HSD), and mast cell activation syndrome (MCAS). Migraine is one of the most common comorbidities of POTS, HSD, and MCAS; conversely, these conditions are also prevalent in patients with migraine, especially in those with multiple systemic symptoms, such as chronic dizziness, lightheadedness, orthostatic intolerance, joint pain, and allergic symptoms. Diagnostic criteria, pathophysiologic mechanisms, and therapeutic considerations in patients with migraine and comorbid dysautonomia, HSD, and MCAS are reviewed.

RECENT FINDINGS

Numerous studies indicate a significant overlap and shared pathophysiology in migraine, dysautonomia, HSD, and MCAS. In clinical setting, dysautonomia, HSD, and MCAS may present a diagnostic and therapeutic challenge in patients with migraine and require a high index of suspicion on the part of the neurologist. Diagnosis and treatment of these complex disorders in patients with migraine is essential to comprehensive patient-centric care, reduced symptom burden, and improved functional impairment secondary to both migraine and comorbidities.

The neuromuscular evaluation of postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS) is a diagnosis with a wide spectrum of symptomatology and a variety of clinicopathological associations, including hereditary, autoimmune, and infectious associations. There is little consensus regarding the appropriate diagnostic approach to the condition. The aim of this work was to provide guidance on the initial diagnosis and when and how to expand diagnostic testing. We define the "typical" POTS patient as younger, female, and with a normal examination apart from joint hyperextensibility. Red flags for "atypical" POTS would be older age at onset, male, prominent syncope, review of systems suggestive of specific alternative diagnoses, examination abnormalities other than joint hyperextensibility, or disease refractory to nonpharmacological and other first-line treatments. Although a limited evaluation is appropriate in POTS with typical features, we recommend an expanded and individualized workup in atypical cases, including additional cardiac testing, autonomic testing, neuropathy workup, and/or autoimmune workup (including consideration of Guillain-Barré syndrome), depending on clinical presentation. We emphasize the importance of shared decision-making in this condition for which treatment remains primarily symptomatic regardless of etiology.

Predicting Therapeutic Efficacy of Pharmacological Treatments in Children with Postural Orthostatic Tachycardia Syndrome: A Mini-Review

Postural orthostatic tachycardia syndrome (POTS) is common in children, with an excessive increment in heart rate when moving from the supine to upright position. It has significant negative impacts on the daily life of pediatric patients. The pathogenesis of POTS includes peripheral vascular dysfunction, central hypovolemia, abnormal autonomic function, a high-adrenergic state, impaired skeletal-muscle pump function, the abnormal release of vasoactive factors, and autoimmune abnormalities. Therefore, the empirical use of pharmacological treatments has limited therapeutic efficacy due to the diversity of its mechanisms. A crucial aspect of managing POTS is the selection of appropriate treatment targeting the specific pathogenesis. This review summarizes the commonly used pharmacological interventions, with a focus on their predictive indicators for treatment response. Factors such as heart rate variability, plasma biomarkers, and cardiac-function parameters are discussed as potential predictors of therapeutic efficacy, enabling the implementation of individualized treatment to improve therapeutic effectiveness. This review consolidates the current knowledge on POTS, encompassing its clinical characteristics, epidemiological patterns, underlying pathogenic mechanisms, and predictive indicators for treatment response. Further research is warranted to enhance the understanding of POTS and facilitate the development of more effective therapeutic approaches for this challenging syndrome.

Cardiovascular Considerations in the Management of People With Suspected Long COVID

Approximately 15% of adult Canadians with SARS-CoV-2 infection develop lingering symptoms beyond 12 weeks after acute infection, known as post-COVID condition or long COVID. Some of the commonly reported long COVID cardiovascular symptoms include fatigue, shortness of breath, chest pain, and palpitations. Suspected long-term cardiovascular complications of SARS-CoV-2 infection might present as a constellation of symptoms that can be challenging for clinicians to diagnose and treat. When assessing patients with these symptoms, clinicians need to keep in mind myalgic encephalomyelitis/chronic fatigue syndrome, postexertional malaise and postexertional symptom exacerbation, dysautonomia with cardiac manifestations such as inappropriate sinus tachycardia, and postural orthostatic tachycardia syndrome, and occasionally mast cell activation syndrome. In this review we summarize the globally evolving evidence around management of cardiac sequelae of long COVID. In addition, we include a Canadian perspective, consisting of a panel of expert opinions from people with lived experience and experienced clinicians across Canada who have been involved in management of long COVID. The objective of this review is to offer some practical guidance to cardiologists and generalist clinicians regarding diagnostic and treatment approaches for adult patients with suspected long COVID who continue to experience unexplained cardiac symptoms.

Resting heart rate variability as a diagnostic marker of cardiovascular dysautonomia in postural tachycardia syndrome

OBJECTIVES

Postural orthostatic tachycardia syndrome (POTS) is a disorder of the autonomic nervous system characterised by orthostatic intolerance and orthostatic tachycardia without hypotension. Heart rate variability (HRV) is the most reliable and objective tool for assessing autonomic dysfunction severity. In the present study, we aimed to investigate HRV changes in resting supine position, predicting severity and cardiovascular risk in patients with POTS.

METHODS

We compared 100 POTS patients with 160 healthy controls matched for age and gender in a case-control design. Along with clinical characterization, heart rate variability was evaluated using ambulatory 5 min ECG in lead II and expressed in frequency and time-domain measures.

RESULTS

The resting heart rate of patients with POTS was significantly higher than that of healthy controls. In HRV measures, root mean square successive difference of RR intervals (RMSSD), total and high frequency (HF) powers were statistically lower with an increased low frequency (LF) to high-frequency ratio in patients with POTS compared to healthy controls. Further, stepwise logistic regression analysis showed increased basal HR and LF/HF as significant predictors of POTS and its severity.

CONCLUSIONS

This is the first study on a large cohort of patients with POTS from India wherein HRV was assessed. The study showed reduced parasympathetic activity and increased sympathetic activity in patients with POTS compared to healthy controls. These findings of increased resting heart rate and LF/HF were found to be potential predictors of POTS and future cardiovascular risks, which need to be replicated in a larger and more homogenized cohort.

Awareness of postural orthostatic tachycardia syndrome is required in adolescent syncope

We investigated head-up tilt test (HUTT) results across age-groups in syncope/presyncope patients to establish pediatric postural orthostatic tachycardia syndrome (POTS) characteristics. We retrospectively reviewed syncope patients' medical records. Adolescents were defined as 10 to 19 years old, adults as 20 to 59 years old, and older individuals as ≥60 years old. From HUTT results, we determined POTS prevalence and differences among the age-groups. We included 147 adolescents, 269 adults, and 123 older patients. Seventy (13.0%) patients (61.4% females; median age: 20 [17-25] years) were diagnosed with POTS. The syndrome was more prevalent among adolescents (33 [22.4%]) than adults (37 [13.8%]), and was absent among older individuals. Affected adolescents had significantly lower resting diastolic blood pressure (DBP) and heart rate (HR), and converted to maximum HR more rapidly than adolescents without the syndrome during the passive phase. Adolescents with POTS demonstrated several unique characteristics compared to adults with and adolescents without this syndrome. POTS may be underrecognized among syncope and presyncope patients, among which 22.4% of adolescents were diagnosed with the syndrome. POTS should be considered when evaluating syncope patients.

Skin Biopsy and Quantitative Sudomotor Axon Reflex Testing in Patients With Postural Orthostatic Tachycardia Syndrome

PURPOSE

No formal diagnostic criteria exist for the neuropathic subtype of postural orthostatic tachycardia syndrome (POTS). Skin biopsy and quantitative sudomotor axon reflex testing (QSORT) are preferred methods of assessment for autonomic small fiber neuropathy (SFN). This study characterizes the utility of these testing methods at a tertiary center and identifies clinical features associated with abnormal testing.

METHODS

Medical records of 2658 patients undergoing tilt table testing at a single institution between June 2018 and December 2020 were reviewed. Patients with postural orthostatic tachycardia syndrome were included for analysis of intraepidermal nerve fiber density (IENFD), sweat output, comorbidities, symptoms, measures of cardiovascular autonomic function, and serum antibody levels.

RESULTS

356 patients (90% female, mean age 31 ± 10) met the diagnostic criteria for postural orthostatic tachycardia syndrome. Of 211 patients who underwent quantitative sudomotor axon reflex testing, 70 (33%) demonstrated reduced sweat output. These patients were more likely to demonstrate sympathetic impairment during the Valsalva maneuver. Of 80 patients who underwent skin biopsies, 19 (24%) demonstrated reduced intraepidermal nerve fiber density. These patients tended to be older and have reduced heart rate variability during deep breathing. Neither test was associated with specific serum antibodies, symptoms, or comorbidities, though there was a trend toward higher rates of comorbid autoimmune disease in patients with abnormal testing.

CONCLUSION

A subset of patients with postural orthostatic tachycardia syndrome have evidence of small fiber neuropathy. These patients tend to have impaired cardiovascular autonomic function but are otherwise similar to patients with no evidence of small fiber neuropathy.

Headache and Autonomic Dysfunction: a Review

PURPOSE OF REVIEW

We explore the anatomy of the central and peripheral autonomic pathways involved in primary headache as well as the mechanisms for secondary headache associated with disorders of the autonomic nervous system. The prevalence and clinical presentation of cranial and systemic autonomic symptoms in these conditions will be discussed, with a focus on recent studies.

RECENT FINDINGS

Several small studies have utilized the relationship between headache and the autonomic nervous system to identify potential biomarkers to aid in diagnosis of migraine and cluster headache. Headache in postural orthostatic tachycardia syndrome (POTS) has also been further characterized, particularly in its association with orthostatic headache and spontaneous intracranial hypotension (SIH). This review examines the pathophysiology of primary and secondary headache disorders in the context of the autonomic nervous system. Mechanisms of headache associated with systemic autonomic disorders are also reviewed.

Postural orthostatic tachycardia syndrome and post-acute COVID-19

While the acute illness of COVID-19 was the initial focus of concern, there are increasing reports of patients with chronic symptoms, known as long-COVID. Dysautonomia may be a possible post-acute neurological complication explaining the persistent symptoms observed in long COVID. Postural tachycardia syndrome (POTS), a form of dysautonomia characterized by sustained tachycardia and orthostatic intolerance, has been increasingly reported in patients after SARS-CoV-2 infection. In this context, this review aimed to report and discuss the available literature pertaining to post COVID-19 POTS.

Tolerability of COVID-19 mRNA vaccines in patients with postural tachycardia syndrome: a cross-sectional study

Background: Postural tachycardia syndrome (POTS) is a form of autonomic dysregulation. There is increasing evidence that the etiology may be immune-mediated in a subgroup of patients. Patients with POTS often experience an exacerbation of their symptoms associated with (viral) infections and often fear the same symptom aggravation after vaccination. In this report we describe the tolerability of messenger ribonucleic acid (mRNA) vaccines against coronavirus disease 19 (COVID-19) and the consequences of a COVID-19 infection on POTS symptoms in our cohort of patients with neuropathic POTS. Methods: We conducted a standardized, checklist-based interview with 23 patients and recorded the acute side effects of mRNA vaccination, acute symptoms of COVID-19 infection as well as the effects of vaccination and COVID-19 infection on POTS symptoms. Results: Of all included patients, 20 patients received two mRNA vaccines without having had a previous COVID-19 infection, and five patients in total had suffered a COVID-19 infection. Of these, three had COVID-19 without and two after being vaccinated. No increased frequency of side effects after both doses of mRNA vaccines was observed. Six patients reported a mild and short-term aggravation of their POTS symptoms beyond the duration of acute vaccine side effects. All five patients who suffered a COVID-19 infection subsequently reported a pronounced and persistent exacerbation of POTS symptoms. Conclusions: Our observations suggest that mRNA vaccines are not associated with a higher frequency of acute side effects in patients with POTS. Symptom exacerbation as a consequence of mRNA vaccination seems to be less frequent and of shorter duration compared to patients who suffered a COVID-19 infection.

Vestibular-autonomic interactions: beyond orthostatic dizziness

PURPOSE OF REVIEW

This review aims to summarize the current literature describing vestibular-autonomic interactions and to describe their putative role in various disorders' clinical presentations, including orthostatic dizziness and motion sensitivity.

RECENT FINDINGS

The vestibular-autonomic reflexes have long been described as they relate to cardiovascular and respiratory function. Although orthostatic dizziness may be in part related to impaired vestibulo-sympathetic reflex (orthostatic hypotension), there are various conditions that may present similarly. A recent clinical classification aims to improve identification of individuals with hemodynamic orthostatic dizziness so that appropriate recommendations and management can be efficiently addressed. Researchers continue to improve understanding of the underlying vestibular-autonomic reflexes with recent studies noting the insular cortex as a cortical site for vestibular sensation and autonomic integration and modulation. Work has further expanded our understanding of the clinical presentation of abnormal vestibular-autonomic interactions that may occur in various conditions, such as aging, peripheral vestibular hypofunction, traumatic brain injury, and motion sensitivity.

SUMMARY

The vestibular-autonomic reflexes affect various sympathetic and parasympathetic functions. Understanding these relationships will provide improved identification of underlying etiology and drive improved patient management.

Postural tachycardia syndrome (POTS) and antiphospholipid syndrome (APS): What do we know so far?

As part of the non-criteria clinical manifestations, postural orthostatic tachycardia syndrome (POTS), a multisystem autonomic dysfunction, can co-exist with antiphospholipid syndrome (APS). Several pieces of evidence hint on the autoimmune basis of POTS, and its possible association with several autoimmune diseases, including APS. Indeed, the evidence exists in the etiologies, symptomatology, and treatment options. Although infections, viral ones in particular, stress, and pregnancy are etiologies to both POTS and APS, the exact pathophysiological connection is still to be studied taking into consideration the activity of cytokines in both diseases. Nevertheless, certain immunomodulatory treatments used for the catastrophic or obstetrical forms of APS, such as intravenous immunoglobulins (IVIG) and steroids, have been also used for the treatment of POTS resistant to classical treatments. Therefore, our review aims to highlight the association between POTS and APS, shedding light on the common etiologies explaining the pathophysiology of the two disorders, the diagnostic approach to POTS as a possible clinical criterion of APS, and the treatment of APS in the context of treating POTS.

Daily Functionality in Adults with POTS: Predictive Factors

Symptoms associated with postural orthostatic tachycardia syndrome (POTS) hinder overall functionality. This study examined factors that impacted daily life and contributed to overall daily functionality in adults with POTS (n = 958, ages 18-60). Descriptive and multiple linear regression analyses indicated that participants with fewer challenges in ADLs, IADLs, work, school, leisure, and socializing had overall better functionality. Furthermore, 'younger age with exercise tolerance', 'having a job', and 'no falls in the last year' were predictors of better functionality. A comprehensive approach to addressing physical, environmental, and psychological factors could help improve overall functionality and enhance quality of life in individuals with POTS.

[Tachycardia and syncope in a 15-year-old teenager]

Patients with highly symptomatic tachycardia may suffer significantly; in addition to a standardized rule-out of structural heart disease, secondary causes need to be excluded. Disorders such as inappropriate sinus tachycardia and postural tachycardia syndrome are caused by cardiac autonomic dysregulation which may be part of a rare underlying noncardiac disease.

Functional status in postural tachycardia syndrome

Introduction

Postural tachycardia syndrome is a form of orthostatic intolerance that often leads to functional impairment.

Methods

This survey explored functional status and impact of symptoms in adults ( n = 958) ages 18 to 60 (M = 32.63 ± 10.52 years, 96.7% female) with postural tachycardia syndrome.

Results

Individuals reported an average of 11 daily life activities impacted by postural tachycardia syndrome with high levels of self-perceived disability. Additionally, 93.4% reported some degree of cognitive impairment and falls occurred in 55.3% of participants annually. Despite frequent falls and functional impairment, participants infrequently (26.9%) utilized therapy services.

Conclusion

Individuals with postural tachycardia syndrome are at an increased risk of experiencing disability and often require assistance with daily activities. Further research is necessary to understand the potential role of therapy in improving function and quality of life.

Ablation therapy of postural orthostatic tachycardia syndrome, inappropriate sinus tachycardia and primary electrical diseases: new insights in invasive treatment options in severely symptomatic patients

Achieving the goal management of some arrhythmic syndromes can be challenging; medical treatment for inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia syndrome (POTS) may be ineffective, necessitating multidisciplinary team treatment. Implantable defibrillator devices (ICDs), along with anti-arrhythmic drugs (AADs), remain the first-line treatment for primary electrical diseases that pose a risk of sudden cardiac death (SCD). Ablation of the arrhythmogenic substrate is not always suggested in patients with these pathologies, but it may be a valuable support for reducing arrhythmic burden, improving quality of life, and treating pathologies that are resistant to pharmacological treatment; however, this option is not often considered due to the potential risks associated with an invasive approach. Minimally invasive hybrid ablation in these syndromes, such as a hybrid thoracoscopic approach and the use of non-invasive mapping systems, reduces post-surgery complications and ensures the best possible outcome for the patient.

Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting - Part 1

Postural orthostatic tachycardia syndrome (POTS) is a chronic and often disabling disorder characterized by orthostatic intolerance with excessive heart rate increase without hypotension during upright posture. Patients often experience a constellation of other typical symptoms including fatigue, exercise intolerance and gastrointestinal distress. A typical patient with POTS is a female of child-bearing age, who often first displays symptoms in adolescence. The onset of POTS may be precipitated by immunological stressors such as a viral infection. A variety of pathophysiologies are involved in the abnormal postural tachycardia response; however, the pathophysiology of the syndrome is incompletely understood and undoubtedly multifaceted. Clinicians and researchers focused on POTS convened at the National Institutes of Health in July 2019 to discuss the current state of understanding of the pathophysiology of POTS and to identify priorities for POTS research. This article, the first of two articles summarizing the information discussed at this meeting, summarizes the current understanding of this disorder and best practices for clinical care. The evaluation of a patient with suspected POTS should seek to establish the diagnosis, identify co-morbid conditions, and exclude conditions that could cause or mimic the syndrome. Once diagnosed, management typically begins with patient education and non-pharmacologic treatment options. Various medications are often used to address specific symptoms, but there are currently no FDA-approved medications for the treatment of POTS, and evidence for many of the medications used to treat POTS is not robust.

COVID-19 Dysautonomia

Objective: To report a case series of dysautonomia associated with COVID-19 infection.

Methods: This is a retrospective review of patients evaluated in the autonomic clinic at our institution with suspected signs and symptoms of dysautonomia who underwent formal evaluation, including autonomic testing.

Results: Six patients were identified with signs and symptoms suggestive of dysautonomia who underwent autonomic testing. All patients had symptoms typical of COVID-19 infection, though none were hospitalized for these or other symptoms. All patients reported symptoms of postural lightheadedness and near-syncope, fatigue, and activity intolerance. Five patients reported the onset of autonomic symptoms concomitant with other COVID-19 symptoms, with the other patient reporting symptom onset 6 weeks following initial COVID-19 symptoms. Autonomic testing demonstrated an excessive postural tachycardia in 4 patients, a hypertensive response with head-up tilt in 3 patients, orthostatic hypotension in 1 patient, and sudomotor impairment in 1 of the patients with excessive postural tachycardia.

Conclusions: We present clinical features and results of autonomic testing in 6 patients with a history COVID-19 infection. While all patients reported typical features of orthostatic intolerance, fatigue, and activity intolerance, the results of autonomic testing were heterogenous, with orthostatic hypotension in 1 patient, excessive postural tachycardia typical of postural tachycardia syndrome in 4 patients, and postural hypertension in 3 patients.

Cutaneous alpha-synuclein deposition in postural tachycardia patients

Objective

To report a case series of patients with neuropathic POTS and cutaneous phosphorylated alpha‐synuclein (P‐SYN) deposition on skin biopsy and compare these to neuropathic POTS patients without P‐SYN deposition.

Methods

The medical history, physical examination findings, autonomic function testing, and skin biopsy neuropathology of patients under the age of 50 with a postural tachycardia and a diagnosis of POTS were retrospectively reviewed. Included patients completed the composite autonomic severity score (COMPASS 31), the Wood Mental Fatigue Inventory, the Epworth Sleepiness scale, the REM Behavior Disorder Questionnaire, the Patient‐Reported Outcomes Measurement Information System (PROMIS‐10), and the Gastroparesis Cardinal Symptom Index.

Results

Of 296 patients seen with POTS, 22 patients with suspected neuropathic POTS had skin biopsies performed during their evaluation. Seven of 22 patients had P‐SYN present on skin biopsy, while 15 individuals did not. Those with P‐SYN on biopsy: (1) were more likely to be male; (2) had features of REM sleep behavioral disorder; (3) reported less sleepiness and cognitive impairment; and (4) noted greater symptoms of gastroparesis. On autonomic testing, the group with P‐SYN deposition was more likely to have a hypertensive response to tilt‐table testing and abnormal QSART responses.

Interpretation

Phosphorylated alpha‐synuclein deposition is present in some postural tachycardia patients with neuropathic features. Individuals with a postural tachycardia and cutaneous phosphorylated alpha‐synuclein deposition may be distinguished from other patients with neuropathic POTS.

When POTS is the tip of the iceberg: Rare cases of dysautonomia as a possible manifestation of another disorder

BACKGROUND

Postural tachycardia syndrome (POTS) is a heterogenous disorder of the autonomic nervous system that is commonly associated with small fiber neuropathy, Ehlers-Danlos Syndrome and autoimmune disorders, but association with rare conditions may also occur.

METHODS

Reported here are clinical features, diagnostic tests and treatment outcomes of 6 unique patients who presented with POTS and were subsequently diagnosed with Fabry disease, McArdle disease, Complex V mitochondrial disease, carcinoid tumor, Hodgkin's lymphoma and chemotherapy-induced neuropathy.

RESULTS

All patients (age range 15-57 years, 3 females, 3 males) presented with orthostatic intolerance of at least 6 months duration, and all patients had co-morbid small fiber neuropathy. Five patients presented with symptoms of POTS months to years before the underlying or associated medical condition was discovered, and three out of six patients experienced either complete resolution or significant improvement of POTS after treatment of the underlying or associated medical condition.

CONCLUSION

In rare cases, POTS can present as a possible manifestation of genetic, neoplastic or neurotoxic disorders. Unusual clinical features that fall outside of the typical spectrum of dysautonomia can point toward the presence of another disorder and help guide further diagnostic investigation.

Non-Pharmacological and Pharmacological Management of Cardiac Dysautonomia Syndromes

Vasovagal syncope, postural orthostatic tachycardia syndrome, and inappropriate sinus tachycardia comprise a heterogenous group of common autonomic disorders that are associated with significant symptoms that impair quality of life. Clinical management of these disorders should prioritize conservative non-pharmacological therapies and consider incorporating pharmacological agents for recurrences. The selection and titration of medications may be complicated by the occurrence of potentially overlapping pathophysiological variants, differences in specific clinical presentations, and commonly associated comorbidities. However, with appropriate long-term management and specialist input, most patients note both symptomatic improvement and functional restoration over time.

Daily Life Experiences: Challenges, Strategies, and Implications for Therapy in Postural Tachycardia Syndrome (POTS)

Postural tachycardia syndrome (POTS) is a condition of orthostatic intolerance which often leads to significant functional deficits. This study explores narrative responses from a large cohort (n = 958) of individuals with POTS in describing daily life challenges and the use of strategies to manage these difficulties. Data was coded and emergent themes provided insight into daily life experiences including successful interventions and a wealth of gaps in treatment that remain unaddressed. This led to the development of clinical recommendations for occupational therapy treatment of individuals with POTS. Further research is indicated including clinical trials to demonstrate the efficacy of occupational therapy intervention.

Autonomic neuropathies

Autonomic neuropathies represent a complex group of disorders that preferentially target autonomic fibers and can be classified as either acute/subacute or chronic in onset. Acute-onset autonomic neuropathies manifest with such conditions as paraneoplastic syndromes, Guillain-Barre syndrome, Sjögren syndrome, infection, or toxins/chemotherapy. When the presentation is acute, immune-mediated, and without a secondary cause, autoimmune autonomic ganglionopathy is likely, and should be considered for immunotherapy. Of the chronic-onset forms, diabetes is the most widespread and disabling, with autonomic impairment portending increased mortality and cardiac wall remodeling risk. Acquired light chain (AL) and transthyretin (TTR) amyloidosis represent two other key etiologies, with TTR amyloidosis now amenable to newly-approved gene-modifying therapies. The COMPASS-31 questionnaire is a validated outcome measure that can be used to monitor autonomic severity and track treatment response. Symptomatic treatments targeting orthostatic hypotension, among other symptoms, should be individualized and complement disease-modifying therapy, when possible.

[Syncopes]

Syncopes are defined as sudden and short unconsciousness with loss of muscular tonus which are reversible without further intervention. Differentiation from other short-lasting changes of consciousness as in seizures, blood flow abnormalities of brainstem, metabolic disorders, intoxication or traumatic loss of consciousness is important for further diagnostic and adequate treatment.

Functional capacity and quality of life in the postural tachycardia syndrome: A retrospective cross-sectional study

Background

Postural tachycardia syndrome (POTS) is a complex syndrome of orthostatic intolerance that significantly affects quality of life. The relationship between functional capacity, quality of life, and age remains poorly understood in this patient population. The purpose of this cross-sectional study was to assess the clinical and exercise characteristics of patients with POTS who underwent exercise stress testing as part of cardiac rehabilitation, and to evaluate the relationships between functional capacity with age and sex, as well as the relationship between functional capacity and quality of life.

Methods

We included 255 consecutive adult patients with the diagnosis of POTS, by tilt table testing, who underwent exercise stress testing between 2012 and 2017. Clinical and stress test data were obtained from electronic medical records.

Results

Of the 255 patients, 232 (91%) were women, with median age 33.5 years. Prevalence of traditional CAD risk factors was low (2% diabetes, 13% hypertension, 7% hyperlipidemia, and 26% smoking history). Mean resting BP was 114 ± 13 mmHg systolic, resting HR was 76 ± 13 bpm, METs achieved 9.2 ± 2.2, and 1 min HR recovery 32 ± 17 bpm. 113 patients (44%) had abnormal functional capacity for age and sex. When analyzed by age groups, younger POTS patients had increasingly lower than expected functional capacity (compared to predicted normals) than did older patients (ANOVA P = 0.0017). The SF-36 physical component of patients with abnormal functional capacity was significantly lower than those with normal functional capacity. (p = 0.006).

Conclusions

In this large cohort, patients with POTS were predominantly female (91%) and relatively young. The novel findings are that younger patients with POTS were more likely to have lower-than-average functional capacity for their age and sex compared to older patients, and that abnormal functional capacity was associated with lower quality of life by SF-36 physical component.

Defining Cardiac Dysautonomia - Different Types, Overlap Syndromes; Case-based Presentations

The cardiovascular branch of autonomic nervous system (ANS) is responsible for the regulation of heart rate, blood pressure, and maintaining homeostasis during physiological stress such as exercise and standing upright. ANS constantly controls the rate and force of heart contractions and the vascular tone with the aim to maintain the sufficient tissue perfusion with oxygenated blood and secure venous return to the heart. Dysautonomias, result of ANS malfunction, are often found in patients with cardiovascular symptoms. Apart from the most prevalent one, arterial hypertension, the cardiovascular dysautonomic continuum encompasses other important although less known conditions: postural orthostatic tachycardia syndrome, inappropriate sinus tachycardia, orthostatic hypotension and reflex syncope. Moreover, heart diseases may evoke autonomic imbalance by themselves; cardiac pump failure is usually associated with sympathetic hyperactivity, neuroendocrine vasopressor activation, higher heart rate, reduced heart rate variability and baroreflex hyposensitivity, all of which are predictors of adverse outcomes. Cardiologists and electrophysiologist frequently see patients for the evaluation and management of unexplained syncope, orthostatic intolerance, heart rhythm abnormalities and symptoms of palpitations. Recognizing the presence of cardiac dysautonomia is an important skill which is necessary for the appropriate evaluation and treatment of these patients. Clinical presentations may overlap, and the importance of a thorough history cannot be over-emphasized. In this review we will present a cases of a patients with cardiac dysautonomia which is illustrative of a typical patient experience, followed by a review of the autonomic nervous system and discussion of prevalence, clinical presentation, and pathophysiology of common cardiac dysautonomias.

Reduced 24-h Sodium Excretion Is Associated With a Disturbed Plasma Acylcarnitine Profile in Vasovagal Syncope Children: A Pilot Study

Objective: To investigate if the low sodium intake is associated with the plasma carnitine and acylcarnitine profile in children with vasovagal syncope (VVS). Materials and Methods: Twenty-six children suffering from VVS were recruited in the present study and divided into a group of low urinary sodium excretion or a group of normal urinary sodium excretion according to the excretion of 24-h urinary sodium <3 or 3-6 g, respectively. The excretion of 24-h urinary sodium was detected with ion-selective electrode approach. Plasma carnitine and acylcarnitine concentrations were measured with tandem mass spectrometry. Each participant completed the head-up tilt test. The demographics, clinical characteristics, hemodynamic parameters and plasma carnitine and acylcarnitine concentrations were compared between the two groups. A bivariate correlation between plasma acylcarnitine profiles and the excretion of 24-h urinary sodium was conducted with Spearman's correlation coefficients. Results: Of the enrolled VVS patients, 14 patients were assigned to the group of low urinary sodium excretion and the remaining 12 patients were assigned to the group of normal urinary sodium excretion. Symptoms of fatigue were more prevalent in the group of low urinary sodium excretion than in the group of normal urinary sodium excretion (p = 0.009). Aside from fatigue, no other differences in the demographics, clinical characteristics or hemodynamic parameters during the head-up tilt test were found between the two groups (p > 0.05). Concentrations of plasma tiglylcarnitine (C5:1), hydroxyhexadecanoylcarnitine (C16OH), hydroxyoctadecanoylcarnitine (C18OH), and carnitine C22 were significantly higher in the group of low urinary sodium excretion than in the group of normal urinary sodium excretion (all p-values = 0.048); moreover, they were all negatively correlated with 24-h urinary sodium levels (all p-values = 0.016). There were no differences between the two groups in other acylcarnitines or free carnitine. Conclusions: Reduced excretion of 24-h urinary sodium is associated with a disturbed plasma acylcarnitine profile in children with VVS. The findings suggest that restricted sodium intake-induced disturbance of plasma acylcarnitines and related cellular energy metabolism might be involved in the pathogenesis of VVS in children.

Autonomic and peripheral neuropathy with reduced intraepidermal nerve fiber density can be observed in patients with gastrointestinal dysmotility

Neuropathy should be considered as a possible etiological factor in patients with severe gastrointestinal symptoms, without signs of disease on routine investigations. Examinations of the autonomic and peripheral nervous systems may be helpful to select the patients who should be investigated with full-thickness intestinal biopsy, and to give appropriate care.

Susceptibility to diarrhea is related to hemodynamic markers of sympathetic activation in the general population

Objectives: Functional gastrointestinal (GI) symptoms, such as IBS (irritable bowel syndrome), have been suggested to be associated with autonomic neuropathy. We therefore examined associations between hemodynamic indices of autonomic control, functional GI symptoms and stress in a population-based cohort.Methods and materials: The study included 2094 participants of the Malmö Offspring Study (mean age 40.6 ± 13.8 years, 53.9% women). 509 (24.3%) reported having GI symptoms the last 2 weeks, without having organic GI disease, and 347 subjects (16.6%) reported IBS. Office and ambulatory 24-h systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were measured. Associations between hemodynamic parameters and abdominal pain, diarrhea, constipation, bloating and flatulence, vomiting and nausea and psychological well-being according to the visual analog scale for IBS (VAS-IBS), and stress, were performed by Spearman's correlation test and linear regression models.Results: Subjects who reported GI symptoms had lower office supine and standing DBP and lower 24 h SBP and DBP compared with those without GI symptoms. Regarding specific symptoms, diarrhea was correlated with 24-h measurements of SBP (rs = 0.197), DBP (rs = 0.173) and heart rate (rs = 0.134). Subjects with the most severe diarrhea had higher 24-h SBP (125.2 vs. 119.0 mmHg; p = .038), DBP (74.0 vs. 69.0 mmHg; p = .033) and heart rate (74.5 vs 71.1 beats/minute; p = .048), after adjustments for confounders, compared to the other. There were no associations between other GI symptoms, IBS, stress and hemodynamic alterations.Conclusion: Functional diarrhea was associated with hemodynamic indices of sympathetic activation, supporting a possible role of the autonomic nervous system in diarrhea.

Adrenergic Autoantibody-Induced Postural Tachycardia Syndrome in Rabbits

Background Previous studies have demonstrated that functional autoantibodies to adrenergic receptors may be involved in the pathogenesis of postural tachycardia syndrome. The objective of this study was to examine the impact of these autoantibodies on cardiovascular responses to postural changes and adrenergic orthosteric ligand infusions in immunized rabbits. Methods and Results Eight New Zealand white rabbits were coimmunized with peptides from the α1-adrenergic receptor and β1-adrenergic receptor (β1AR). Tilt test and separate adrenergic agonist infusion studies were performed on conscious animals before and after immunization and subsequent treatment with epitope-mimetic peptide inhibitors. At 6 weeks after immunization, there was a greater percent increase in heart rate upon tilting compared with preimmune baseline. No significant difference in blood pressure response to tilting was observed. The heart rate response to infusion of the β-adrenoceptor agonist isoproterenol was significantly enhanced in immunized animals, suggesting a positive allosteric effect of β1AR antibodies. In contrast, the blood pressure response to infusion of the α1-adrenergic receptor agonist phenylephrine was attenuated in immunized animals, indicating a negative allosteric effect of α1-adrenergic receptor antibodies. Injections of antibody-neutralizing peptides suppressed the postural tachycardia and reversed the altered heart rate and blood pressure responses to orthosteric ligand infusions in immunized animals at 6 and 30 weeks. Antibody production and suppression were confirmed with in vitro bioassays. Conclusions The differential allosteric effect of α1-adrenergic receptor and β1AR autoantibodies would lead to a hyperadrenergic state and overstimulation of cardiac β1AR. These data support evidence for an autoimmune basis for postural tachycardia syndrome.

[Hemodynamic changes in standing-up test of children and adolescents with postural tachycardia syndrome]

OBJECTIVE

To explore the hemodynamic changes in standing-up test of children and adolescents with postural tachycardia syndrome (POTS) and to compare hemodynamic parameters of POTS patients with decreased cardiac index (CI) and those with not-decreased CI.

METHODS

A retrospective study was conducted to show the trends of CI, total peripheral vascular resistance index (TPVRI), heart rate and blood pressure in standing-up test of 26 POTS patients and 12 healthy controls, and to compare them between the two groups. The POTS patients were divided into two groups based on CI decreasing or not in standing-up test, namely decreased CI group (14 cases) and not-decreased CI group (12 cases). The trends of the above mentioned hemodynamic parameters in standing-up test were observed and compared between decreased CI group and not-decreased CI group.

RESULTS

In standing-up test for all the POTS patients, CI (F=6.936, P=0.001) and systolic blood pressure (F=6.049, P<0.001) both decreased significantly, and heart rate increased obviously (F=113.926, P<0.001). However, TPVRI (F=2.031, P=0.138) and diastolic blood pressure (F=2.018, P=0.113) had no significant changes. For healthy controls, CI (F=3.646, P=0.016), heart rate (F=43.970, P<0.001), systolic blood pressure (F=4.043, P=0.020) and diastolic blood pressure (F=8.627, P<0.001) all increased significantly in standing-up test. TPVRI (F=1.688, P=0.190) did not change obviously. The changing trends of CI (F=6.221, P=0.001), heart rate (F=6.203, P<0.001) and systolic blood pressure (F=7.946, P<0.001) over time were significantly different between the patients and healthy controls, however, no difference was found in TPVRI and diastolic blood pressure (P > 0.05). Among the POTS patients, CI was significantly different between decreased CI group and not-decreased CI group (F=14.723, P<0.001). Systolic blood pressure of the former decreased obviously (F=8.010, P<0.001), but it did not change obviously in the latter (F=0.612, P=0.639). Furthermore, none of the changes of TPVRI, heart rate and diastolic blood pressure in standing-up test were significantly different between the two groups (P > 0.05). Age was an independent factor for decreased CI patients (P=0.013, OR=2.233; 95% CI, 1.183 to 4.216).

CONCLUSION

POTS patients experience vital hemodynamic changes in standing-up test, part of them suffering from decreased CI, but others from not-decreased CI. Age is an independent factor for patients suffering from decreased CI.

Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management

Postural orthostatic tachycardia syndrome (POTS) is a variant of cardiovascular autonomic disorder characterized by an excessive heart rate increase on standing and orthostatic intolerance. POTS affects younger individuals 15-45 years old with a distinct female predominance (≈80%). The prevalence ranges between 0.2% and 1.0% in developed countries. The onset of POTS is typically precipitated by immunological stressors such as viral infection, vaccination, trauma, pregnancy, surgery or psychosocial stress. The most common complaints are dizziness, weakness, rapid heartbeat and palpitation on standing. Moreover, patients often report physical deconditioning and reduced exercise capacity as well as headache, 'brain fog', dyspnoea, gastrointestinal disorders and musculoskeletal pain. The aetiology of POTS is largely unknown and three main hypotheses include an autoimmune disorder, abnormally increased sympathetic activity and catecholamine excess, and sympathetic denervation leading to central hypovolaemia and reflex tachycardia. The golden standard for POTS diagnosis is head-up tilt test with a non-invasive beat-to-beat haemodynamic monitoring. Although long-term prognosis of POTS is poorly explored, around 50% of patients spontaneously recover within 1-3 years. After the diagnosis has been established, patient should be thoroughly educated about non-pharmacological measures alleviating the symptoms. Exercise training may be very effective and counteract deconditioning. In more symptomatic patients, different drugs directed at controlling heart rate, increasing peripheral vasoconstriction and intravascular volume can be tested. However, the overall effects of pharmacological therapy are modest and the most affected patients remain handicapped. Future efforts should focus on better understanding of POTS pathophysiology and designing randomized controlled trials for selection of more effective therapy.

Proconvertase Furin Is Downregulated in Postural Orthostatic Tachycardia Syndrome

Background: Postural Orthostatic Tachycardia Syndrome (POTS) is a cardiovascular autonomic disorder characterized by orthostatic intolerance and high prevalence among young women. The etiology of POTS is uncertain, though autoimmunity and inflammation may play an important role. We aimed to identify novel inflammatory biomarkers associated with POTS.

Methods and Results: In the Syncope Study of Unselected Population in Malmö (SYSTEMA) cohort, we identified 396 patients (age range, 15–50 years) with either POTS (n = 113) or normal haemodynamic response during passive head-up-tilt test (n = 283). Blood samples were analyzed using antibody-based Proximity Extension Assay technique simultaneously measuring 57 inflammatory protein biomarkers. The discovery algorithm was a sequential two-step process of biomarker signature identification by supervised, multivariate, principal component analysis and verification by univariate ANOVA with Bonferroni correction. POTS patients were younger (26 vs. 31 years; p < 0.001) and there was no significant difference in sex distribution (74% vs. 67% females, p = 0.24). PCA and Bonferroni-adjusted ANOVA identified proconvertase furin as the most robust biomarker signature for POTS. Plasma level of proconvertase furin was lower (6.38 vs. 6.58 of normalized protein expression units (NPX); p < 0.001 in POTS, compared with the reference group. Proconvertase furin met Bonferroni-adjusted significance criteria in both uni- and multivariable regression analyses.

Conclusion: Patients with POTS have lower plasma level of proconvertase furin compared with individuals with normal postural hemodynamic response. This finding suggests the presence of a specific autoimmune trait with disruption of immune peripheral tolerance in this hitherto unexplained condition. Further studies are needed for external validation of our results.

Value of Immediate Heart Rate Alteration From Supine to Upright in Differential Diagnosis Between Vasovagal Syncope and Postural Tachycardia Syndrome in Children

Objectives: To explore the predictive value of immediate heart rate alteration from supine to upright in the differential diagnosis between vasovagal syncope (VVS) and postural tachycardia syndrome (POTS) in children. Materials and Methods: A total of 76 pediatric outpatients or inpatients who visited the Peking University First Hospital from July 2016 to November 2017 were recruited in the study. Among them, 52 patients were diagnosed with VVS and 24 patients were diagnosed with POTS. The differential diagnostic value of acceleration index (AI) and 30/15 ratio was evaluated by the receiver operating characteristic (ROC) curve. An external validation test was performed in another 46 patients. Results: Compared with the cases in the VVS group, patients in the POTS group had a significantly increased AI but a decreased 30/15 ratio (33.495 ± 8.472 vs. 23.440 ± 8.693, p < 0.001; 0.962 ± 0.067 vs. 1.025 ± 0.084, p = 0.002; respectively). The ROC curves showed that AI and 30/15 ratio were useful for differentiating POTS from VVS. A cut-off value of AI set at 28.180 yielded a sensitivity of 79.2% and a specificity of 73.1%. A cut-off value of 30/15 ratio set at 1.025 yielded a sensitivity of 87.5% and a specificity of 61.5%. A combined use of these two indices improved the sensitivity to 95.8% when either AI or 30/15 was used, and specificity to 80.8% with the use of both AI and 30/15 at the same diagnosis. The external validation test showed that the positive and negative predictive values of the AI and 30/15 ratio were 77.3 and 79.2%, and 72.0 and 81.0%, respectively. The positive predictive value increased to 87.5% when both the AI and 30/15 ratio cut-off values were used together. Conclusions: The AI and 30/15 ratio, which are easy to perform and non-invasive, have proper sensitivity and specificity to differentiate patients with POTS from those with VVS. The combination of these two indices significantly improves the predictive value.

Autonomic regulation during sleep and wakefulness: a review with implications for defining the pathophysiology of neurological disorders

Cardiovascular and respiratory parameters change during sleep and wakefulness. This observation underscores an important, albeit incompletely understood, role for the central nervous system in the differential regulation of autonomic functions. Understanding sleep/wake-dependent sympathetic modulations provides insights into diseases involving autonomic dysfunction. The purpose of this review was to define the central nervous system nuclei regulating sleep and cardiovascular function and to identify reciprocal networks that may underlie autonomic symptoms of disorders such as insomnia, sleep apnea, restless leg syndrome, rapid eye movement sleep behavior disorder, and narcolepsy/cataplexy. In this review, we examine the functional and anatomical significance of hypothalamic, pontine, and medullary networks on sleep, cardiovascular function, and breathing.