Systematic literature review of pathophysiology of postural orthostatic tachycardia syndrome (angiotensin II receptor subtype imbalance theory)

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.

COVID-19-Induced Postural Orthostatic Tachycardia Syndrome and Dysautonomia

Postural orthostatic tachycardia syndrome (POTS) is a disorder characterized by orthostatic intolerance and, by definition, includes clinical symptoms of lightheadedness, palpitations, and tremulousness among others. It is considered a relatively rare condition that affects approximately 0.2% of the general population, and it is estimated that between 500,000 to 1,000,000 individuals in the United States have the condition and recently has been linked to post-infectious (viral) etiologies. We present a case of a 53-year-old woman who was diagnosed with POTS following extensive autoimmune workup, who was also status post-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The post-coronavirus disease 2019 (COVID-19) cardiovascular autonomic dysfunction can affect global circulatory control, which describes increased heart rate even at resting states, and local circulatory disorders, such as coronary microvascular disease leading to vasospasm, as described by the patient's chest pain, and venous retention leading to pooling and reduced venous return after standing. Along with tachycardia with orthostatic intolerance, other symptoms can also accompany the syndrome. In the majority of patients, intravascular volume is reduced, leading to decreased venous return to the heart and causing reflex tachycardia and orthostatic intolerance. Management varies from lifestyle modifications to pharmacologic therapy, to which patients generally show a good response. POTS should be a differential on the cards, especially in patients post-COVID-19 infection, as these symptoms can be misdiagnosed as having psychological etiologies.

Inducible Laryngeal Obstruction Differential Diagnosis in Adolescents and Adults: A Tutorial

Inducible laryngeal obstruction (ILO), formerly referred to as paradoxical vocal fold motion and vocal cord dysfunction, is a complex disorder of the upper airway that requires skillful differential diagnosis. There are several medical conditions that may mimic ILO (or which ILO may mimic) that should be considered in the differential diagnosis before evidence-supported behavioral intervention is initiated to mitigate or eliminate this upper airway condition. A key in treatment planning is determination of an isolated presentation of ILO or ILO concurrent with other conditions that affect the upper airway. Accurate, timely differential diagnosis in the clinical assessment of this condition mitigates delay of targeted symptom relief and/or insufficient intervention. Accurate assessment and nuanced clinical counseling are necessary to untangle concurrent, competing conditions in a single patient. This tutorial describes the common and rare mimics that may be encountered by medical professionals who evaluate and treat ILO, with particular attention to the role of the speech-language pathologist. Speech-language pathologists receive referrals for ILO from several different medical specialists (allergy, pulmonology, and sports medicine), sometimes without a comprehensive team assessment. It is paramount that speech-language pathologists who assess and treat this disorder have a solid understanding of the conditions that may mimic ILO. Summary tables that delineate differential diagnosis considerations for airway noise, origin of noise, symptoms, triggers, role of the speech-language pathologist, and β-agonist response are included for clinician reference. A clinical checklist is also provided to aid clinicians in the critical assessment process.

The Relationship Between Hypermobile Ehlers-Danlos Syndrome (hEDS), Postural Orthostatic Tachycardia Syndrome (POTS), and Mast Cell Activation Syndrome (MCAS)

In recent years, an association between hypermobile Ehlers-Danlos syndrome (hEDS), mast cell activation syndrome (MCAS), and postural orthostatic tachycardia syndrome (POTS) has garnered attention and patients are increasingly presenting with this triad. However, a real relationship between these entities is unclear due to a lack of scientific validity. We conducted an extensive review of the literature using two different search strategies. A narrower strategy included 88 searches of various combinations of terms for each of the three conditions, yielding 19 unique papers. A broader search included 136 searches of various combinations of terms but included all forms of EDS and yielded 40 unique papers. Of these, only four and nine papers from the narrower and broader search strategies were original research articles. None of these papers resulted from a combination of the search terms for the three conditions. All three clinical entities are controversial in either existence or pathogenesis. MCAS is a poorly defined clinical entity, and many studies do not adhere to the proposed criteria when establishing the diagnosis. Patients previously diagnosed with EDS hypermobility type may not meet the new, stricter criteria for hEDS but may for a less severe hypermobility spectrum disorder (HSD). The pathophysiology of POTS is still unclear. An evidence-based, common pathophysiologic mechanism between any of the two, much less all three conditions, has yet to be described. Our review of the literature shows that current evidence is lacking on the existence of MCAS or hEDS as separate or significant clinical entities. Studies proposing a relationship between the three clinical entities are either biased or based on outdated criteria. The reason behind the purported association of these entities stems from an overlapping pool of vague, subjective symptoms, which is inadequate evidence to conclude that any such relationship exists.