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

Abstract

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.

A Nationwide Epidemiological Survey of Adolescent Patients With Diverse Symptoms Similar to Those Following Human Papillomavirus Vaccination: Background Prevalence and Incidence for Considering Vaccine Safety in Japan

“…Regarding frequently reported diagnoses in the present survey, pathogenesis for orthostatic dysregulation or POTS may have included impairment of circulatory adjustment against gravitational stress, altered central blood volume, abnormal autonomic reflexes and elevated sympathetic tone, damaged skeletal muscle pump activity, local vascular tension regulation dysfunction, iron insufficiency, mast cell activation, and autoimmune dysfunction. 43 , 44 In patients with somatoform disorders, morphological alterations that encompass motor, limbic, and somatosensory circuits were observed in neuroimaging research. 45 Although not a frequently reported diagnosis in this study, fibromyalgia can present symptoms similar to diverse symptoms after HPV vaccination because the clinical features of fibromyalgia and persistent somatoform pain disorder or somatization disorder overlap in patients with chronic widespread pain without specific somatic disease factors.…”

Predictive Value of Heart Rate and Blood Pressure on the Prognosis of Postural Tachycardia Syndrome in Children

“…Children with POTS have increased blood volume and electrolytes, increased venous filling, increased venous return and ventricular filling, and increased cardiac output and BP after increased water and salt intake (e.g., take oral rehydration salts) ( 25 ). Meanwhile, because of the increase of venous return, the sympathetic excitability decreased compared with that before treatment, the peripheral vascular resistance decreased, the positive inotropic effect of the heart was relatively weakened, and the mechanism of HR increase before treatment to compensate for the insufficient cardiac output was released, and the tachycardia symptoms were relieved in children with POTS after uprightness ( 26 , 27 ). The treatment of the POTS children with metoprolol directly antagonizes catecholamines at the cellular level, inhibits adrenaline-dependent triggering activity, relatively prolongs ventricular diastole, increases cardiac output per beat, and improves blood volume and muscle sympathetic activity, resulting in a relative improvement in the occurrence of transient ischemia in the brain and a certain degree of relief of POTS symptoms ( 14 , 26 , 28 ).…”

The Application of Head-Up Tilt Test to Diagnose Hemodynamic Type of Orthostatic Intolerance in Children Aged Between 3 and 5 Years

“…For general patients with orthostatic intolerance, non-pharmacologic interventions including health education of avoiding prolonged standing, tilt training, and intake of water and salt were utilized to alleviate the orthostatic intolerant symptom. For patients with positive responses to HUTT, pharmacologic interventions such as midodrine hydrochloride or metoprolol should be used when appropriate ( 21 ). HUTT can not only diagnose the hemodynamic type but can also help with the selection of treatment strategies for orthostatic intolerance.…”