Abstract Details

Title The Role of Cardiovagal Sensitivity in Adolescent Orthostatic Intolerance

Topic Autonomic Disorders

Presentation(s) P03 - (-)

Poster/Presentation
Number 021

Objective

Background BACKGROUND: OI is increasingly recognized among adolescents but pathophysiologic mechanisms remain poorly understood. Patients typically have normal autonomic function based on standardized testing, but we frequently see unusually high values for cardiovagal indices such as HR responses to deep breathing (HRDB) and Valsalva ratio (VR), and hypothesized that there may be an association with the orthostatic HR response. Such relationship would be intriguing in terms of our understanding of mechanisms underlying OI.

Design/Methods DESIGN/METHODS: 100 adolescent patients were randomly selected from a large cohort of patients referred to our laboratory for evaluation of OI. HRDB and VR were quantified using standard techniques. Vagal baroreflex sensitivity (BRS) was defined as slope between systolic blood pressure (BP) decline during phase II and resulting change in RR interval. HR and BP responses to tilt were assessed using 30 second data averages. Correlations analysis was performed between parameters of interest.

Results RESULTS: HRDB and BRS were not correlated with orthostatic ?HR or ?BP. VR was weakly but significantly correlated with ?HR (r=0.37, p=0.001). While VR was strongly correlated with the BP changes during early phase II and phase IV of the VM, only one of these BP indices (phase IV) was weakly correlated with ?HR during tilt. No correlation was seen between BP and HR responses to tilt.

Conclusions CONCLUSIONS: These findings argue against excessive cardiac vagal modulation or excessive BRS underlying the excessive orthostatic HR rise in adolescents with OI. The pattern of findings would rather suggest that the mechanism underlying the excessive orthostatic HR rise also results in excessive BP responses to the VM and consequently excessive VR. This putative mechanism remains subject to further study.

Authors/Disclosures
Wolfgang Singer, MD, FAAN (Mayo Clinic) PRESENTER	Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biohaven. The institution of Dr. Singer has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Lundbeck. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Ionis. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Yoda. Dr. Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Theravance. Dr. Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Ferrer. The institution of Dr. Singer has received research support from NIH. The institution of Dr. Singer has received research support from FDA. The institution of Dr. Singer has received research support from Michael J. Fox Foundation. Dr. Singer has received intellectual property interests from a discovery or technology relating to health care.
	No disclosure on file
Eduardo E. Benarroch, MD, FAAN (Mayo Clinic)	Dr. Benarroch has nothing to disclose.
Paola Sandroni, MD, PhD, FAAN (Mayo Clinic)	Dr. Sandroni has nothing to disclose.
Phillip A. Low, MD, FAAN (Mayo Clinic)	Dr. Low has nothing to disclose.
Bianca Weinstock-Guttman, MD (Department of Neurology, University At Buffalo)	Dr. Weinstock-Guttman has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Biogen. Dr. Weinstock-Guttman has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. Dr. Weinstock-Guttman has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Novartis . Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD Serono. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Abbvie. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Genzyme &Sanofi. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Janssen . Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bayer. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Horizon. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Weinstock-Guttman has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Weinstock-Guttman has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Biogen. Dr. Weinstock-Guttman has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Janssen. Dr. Weinstock-Guttman has received personal compensation in the range of $0-$499 for serving as a Reviewer with NIH.

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