Inappropriate Early Hypotension in Adolescents: A Form of Chronic Orthostatic Intolerance with Defective Dependent Vasoconstriction

Abstract

Instantaneous orthostatic hypotension (INOH) has been reported in children and adolescents as a new entity of orthostatic intolerance in children who underwent rapid standing as an orthostatic stress test. Children with INOH were discovered among patients presenting with symptoms of chronic orthostatic intolerance, which is often related to orthostatic tachycardia. We used head-up tilt table testing at 70°to investigate children presenting with symptoms of chronic orthostatic intolerance. We compared 24 patients aged 12-17 y, with chronic orthostatic intolerance and symptoms for Ն3 mo, with 13 healthy normal control patients. We recorded continuous heart rate, blood pressure, and respiratory rate and used venous occlusion strain gauge plethysmography to measure calf and forearm blood flow while supine and calf blood flow during head-up tilt. Patients with chronic orthostatic intolerance fulfilled criteria for the postural orthostatic tachycardia syndrome. Postural orthostatic tachycardia syndrome patients were divided into two groups by the occurrence of INOH. Supine forearm and calf arterial resistance was decreased in patients with INOH (n ϭ 8) compared with postural orthostatic tachycardia syndrome patients without INOH (n ϭ 16) and compared with control (n ϭ 13). Resting calf venous pressure was elevated, suggesting excess venous filling because of vasodilation. During early head-up tilt, calf blood flow increased markedly in INOH, less in No-INOH, postural orthostatic tachycardia syndrome patients and least in control patients. Flow was temporally related to calf swelling and negatively correlated to hypotension. The data suggest that INOH occurs in patients with chronic orthostatic intolerance and orthostatic tachycardia and is related to rapid caudal blood flow when upright because of a vasoconstrictor defect. INOH has recently been reported as a new entity of orthostatic intolerance in children and adolescents who underwent rapid standing as an orthostatic stress test (1, 2). Data from that original study suggested that some patients developed systolic hypotension whereas others did not. Upright tachycardia was a common feature of all patients. Orthostatic tachycardia with COI has been described at least since 1940 (3) and more recently by investigators designating the syndrome POTS (for postural orthostatic tachycardia syndrome) (4 -6) or COI (7,8) in adults. We and others have described the syndrome in children and adolescents (6, 9 -12), often in the context of the chronic fatigue syndrome (12). We suspect that vascular resistance is lower than healthy control subjects in many COI-POTS patients. We hypothesized that abnormally increased blood flow to the lower extremities in COI-POTS patients during orthostatic challenge related to reduced lower limb resistance causes a precipitous early fall in blood pressureergo INOH. To investigate this hypothesis we used venous occlusion plethysmography to study blood flow supine and during HUT, comparing 24 patients with COI-POTS with 13 healthy control patients....

Taquicardia postural ortostática en 15 pacientes: disautonomía compleja

“…Las diferentes respuestas al tratamiento en los distintos pacientes, puede representar la existencia de distintos subtipos de POTS, hecho que ya han planteado algunos autores [21][22][23][24][25][26] y que debe aclararse.…”

Does non-pharmacological treatment affect outcomes in dysautonomic syndromes?

“…This condition leads to an inefficient venous return and abnormal central blood distribution. The level of vasoconstriction deficiency is associated with different degrees of orthostatic intolerance, being worse in those patients who faint early during tilt table test [9,10].…”