Physiologic neurocirculatory patterns in the head-up tilt test in children with orthostatic intolerance

Background: Orthostatic intolerance (OI) is a common clinical manifestation in clinical pediatrics. The head‐up tilt (HUT) table test is considered the standard of orthostatic assessment, but the physiologic neurocirculatory profile during HUT has not been fully realized in children with OI. The present study, therefore, was designed to investigate the physiologic patterns that occur during HUT in children with OI. Methods: Ninety children (56 girls; mean age, 11.6 ± 2.3 years) with OI underwent HUT under quiet circumstances. Blood pressure and heart rate were monitored simultaneously. Results: Forty‐nine children with OI (54.4%) had vasovagal response with HUT testing; 33 (36.7%), vasodepressor response; six (6.7%), cardioinhibitory response; and 10 (11.1%), mixed response. Twenty‐eight children (31.1%) had postural orthostatic tachycardia; one (1.1%), orthostatic hypotension (OH); and 12 (13.3%), normal physiologic response. Patterns of cerebral syncope response and chronotropic incompetence were not observed. Conclusions: Classical vasovagal response was the major physiologic pattern seen in children with OI during HUT testing, and postural orthostatic tachycardia response ranked second.