Abstract P396: Vitamin D Supplementation Improves Cardiovascular Response to Head Up Tilt in Adolescents Suffering from Syncope

Abstract

Background: In previous work we identified a group of adolescents whose diagnostic workup for chronic unexplained nausea revealed underlying cardiovascular instability manifesting as orthostatic intolerance (OI) and syncope. These patients exhibited impairment in autonomic function and excessive release of catecholamines (Epi / NE) and vasopressin (AVP) upon head up tilt compared to pre tilt. They also had low vitamin D level that correlated with the severity of symptoms on tilt. In this pilot study we hypothesized that vitamin D supplementation to normal levels will improve the cardiovascular response to tilt and reduce NE/Epi and AVP release. Methods: A cohort of seven Adolescents (mean age= 16.2 years) who are vitamin D deficient had a head up tilt at baseline and after two months of vitamin D supplementation (2000-5000 IU daily based on baseline level). Heart rate, blood pressure, NE/Epi and AVP were measured in supine and standing position. Total time on tilt was also recorded. Results: As see in the table. Compared to baseline, vitamin D supplementation reduced the HR elevation post HUT and reduced NE/Epi baseline levels and ameliorated the elevation in AVP after HUT. Conclusions: Vitamin D supplementation for two months restored vitamin D to normal levels and was associated with less nausea symptoms during tilt and lower level of baseline catecholamines. It was also associated with less release of NE/Epi and vasopressin post head up tilt and longer duration of standing on tilt table. These data provides evidence of potential therapeutic benefit of vitamin D supplementation for patients suffering from syncope who are vitamin D deficient