Pediatric Autonomic-Mediated Orthostatic Intolerance
Syncope or near-syncope spells are a relatively common occurrence in older children and adolescents. It has been estimated that 15–30% of adolescents will have at least one episode of syncope before reaching adulthood, with approximately half having multiple episodes. Orthostatic intolerance, recurrent syncope or near-syncope when rising from a seated or lying position, may have an autonomic, cardiac, neurologic, psychiatric, or metabolic cause, or may be idiopathic. Approximately 70–75% of patients are diagnosed with autonomic-mediated orthostatic intolerance. This category includes common vasovagal syncope, as well as postural orthostatic tachycardia syndrome and orthostatic hypotension.
Postural orthostatic tachycardia syndrome (POTS) is defined as syncope or near-syncope associated with dizziness, weakness, and tachycardia (an increase in heart rate of 30 bpm or more in the absence of hypotension) upon standing. In some patients, it has been associated with chronic fatigue after a triggering illness such as Epstein-Barr virus. The incidence of POTS in children and adolescents is much greater than that of orthostatic hypotension. In a recent analysis of 142 children diagnosed with orthostatic intolerance, autonomic testing identified POTS in 71% and orthostatic hypotension in only 5%.
Most children and adolescents diagnosed with autonomic-mediated orthostatic intolerance need only education on maintaining adequate hydration, increasing dietary sodium intake, and removing known triggers. Counter maneuvers (sitting or lying down when symptomatic) and conditioning exercises are also beneficial. Patients with recurrent syncope or orthostatic hypotension, however, may require additional treatment. Traditional therapies for syncope have included fludrocortisone and sodium chloride supplementation, alpha1-adrenergic agonists, and beta-adrenergic blocking agents.
Abstract and Introduction
Introduction
Syncope or near-syncope spells are a relatively common occurrence in older children and adolescents. It has been estimated that 15–30% of adolescents will have at least one episode of syncope before reaching adulthood, with approximately half having multiple episodes. Orthostatic intolerance, recurrent syncope or near-syncope when rising from a seated or lying position, may have an autonomic, cardiac, neurologic, psychiatric, or metabolic cause, or may be idiopathic. Approximately 70–75% of patients are diagnosed with autonomic-mediated orthostatic intolerance. This category includes common vasovagal syncope, as well as postural orthostatic tachycardia syndrome and orthostatic hypotension.
Postural orthostatic tachycardia syndrome (POTS) is defined as syncope or near-syncope associated with dizziness, weakness, and tachycardia (an increase in heart rate of 30 bpm or more in the absence of hypotension) upon standing. In some patients, it has been associated with chronic fatigue after a triggering illness such as Epstein-Barr virus. The incidence of POTS in children and adolescents is much greater than that of orthostatic hypotension. In a recent analysis of 142 children diagnosed with orthostatic intolerance, autonomic testing identified POTS in 71% and orthostatic hypotension in only 5%.
Most children and adolescents diagnosed with autonomic-mediated orthostatic intolerance need only education on maintaining adequate hydration, increasing dietary sodium intake, and removing known triggers. Counter maneuvers (sitting or lying down when symptomatic) and conditioning exercises are also beneficial. Patients with recurrent syncope or orthostatic hypotension, however, may require additional treatment. Traditional therapies for syncope have included fludrocortisone and sodium chloride supplementation, alpha1-adrenergic agonists, and beta-adrenergic blocking agents.