Abstract 304: Elevated Supine Arterial Pressure in Children with Postural Orthostatic Tachycardia
Elevated supine mean arterial pressure (MAP) is often present in adults with dysautonomia. Children 15.1 ± 0.4 yrs of age (n = 22) with chronic unexplained nausea underwent continuous measures of supine blood pressure (BP) and heart rate (HR) pre- and post-tilt (0-70 degrees upright) and spectral analysis of their autonomic profile. Diagnostic workup revealed ∼77% have postural orthostatic tachycardia syndrome (POTS). The controls in this cohort had chronic nausea but were identified as normal upon tilt. Resting supine MAP and HR prior to tilt were higher in POTS subjects compared with controls, while most indices of autonomic function were similar (Table 1). Those diagnosed with POTS maintained MAP during tilt accompanied by a >5-fold increase in cardiac sympathetic drive (LFrri/HFrri) and >80% suppression of the baroreceptor reflex sensitivity (high frequency alpha index;HFα) in comparison to 2-fold and ∼60% responses in controls. BP variability (SDMAP) measured as the standard deviation of mean arterial presuure and HRV measured as the root of mean square of successive differences (rMSSD) were impaired to a greater extent in the POTS subjects. Exaggerated suppression of HRV during upright posture in POTS subjects is known. However, our studies reveal elevated supine MAP even at this young age. In adults, both impaired HRV and elevated supine MAP are risk factors for cardiovascular problems such hypertension and cardiac hypertrophy. Future studies are necessary to determine whether young adults with POTS are at greater risk of early onset cardiovascular disease, especially given the the potential impact of treatments aimed at increasing MAP. Support: AHA12CRP9420029
- © 2012 by American Heart Association, Inc.