Patterns of orthostatic intolerance: the orthostatic tachycardia syndrome and adolescent chronic fatigue.

OBJECTIVES: To describe the orthostatic tachycardia syndrome (OTS) in adolescents, similarities to and differences from chronic fatigue syndrome (CFS), and patterns of orthostatic intolerance during head-up tilt (HUT). STUDY
DESIGN: Using electrocardiography and arterial tonometry, we investigated the heart rate and blood pressure responses during HUT in 20 adolescents with OTS compared with 25 adolescents with CFS, 13 healthy control subjects, and 20 patients with simple faint.
RESULTS: Of the control subjects, 4 of 13 experienced typical vasovagal faints with an abrupt fall in blood pressure and heart rate, and 14 of 20 patients with simple faint experienced similar HUT responses. All patients with CFS (25/25) experienced severe orthostatic symptoms with syncope in 2 of 25, early orthostatic tachycardia during HUT in 16 of 23 (13/16 hypotensive), and delayed orthostatic tachycardia in 7 of 23 (6/7 hypotensive). Acrocyanosis and edema occurred in 18 of 25. Early orthostatic tachycardia occurred in 10 of 20 patients with OTS. Of these, 9 of 10 were hypotensive, but hypotension was delayed in 4 of 9. Delayed tachycardia occurred in 10 of 20 (all hypotensive). Acrocyanosis and edema occurred in most patients with CFS, fewer patients with OTS, and in one patient with simple faint. Orthostatic symptoms were similar but more severe in patients with CFS compared with patients with OTS.
CONCLUSIONS: Symptoms and patterns of orthostatic heart rate and blood pressure change in OTS overlap strongly with those of CFS. Orthostatic intolerance in OTS may represent an attenuated form of chronic fatigue pathophysiology.