Mechanisms of Vasovagal Syncope
Last updated on July 2021Recruitment
- Recruitment Status
- Active, not recruiting
- Estimated Enrollment
- Same as current
Summary
- Conditions
- Postural Tachycardia Syndrome
- Vasovagal Syncope
- Type
- Interventional
- Phase
- Early Phase 1
- Design
- Allocation: N/AIntervention Model: Single Group AssignmentMasking: None (Open Label)Primary Purpose: Diagnostic
Participation Requirements
- Age
- Between 14 years and 29 years
- Gender
- Both males and females
Description
Vasovagal Syncope (VVS,simple faint) is the most common cause of transient loss of consciousness and is the acute episodic form of orthostatic intolerance(OI). Postural tachycardia syndrome (POTS) is the common chronic form of OI. Both are defined by debilitating symptoms and signs while upright rel...
Vasovagal Syncope (VVS,simple faint) is the most common cause of transient loss of consciousness and is the acute episodic form of orthostatic intolerance(OI). Postural tachycardia syndrome (POTS) is the common chronic form of OI. Both are defined by debilitating symptoms and signs while upright relieved by recumbency. Pathophysiological mechanisms have remained elusive although our past work shows that excessive upright central hypovolemia results from splanchnic pooling due to defective splanchnic arterial and venous constriction. Preliminary data support the hypothesis that production of nitric oxide (NO) is enhanced in these patients resulting in reduced sympathetic noradrenergic neurotransmission at pre-junctional and post-junctional sites. Our approach is two-fold: 1) We will use intradermal microdialysis and laser Doppler flowmetry (LDF) to delineate the microvascular mechanisms of NO modulation of noradrenergic neurotransmission free of confounding systemic reflex changes. 2) We will systemically apply this mechanism to a model of orthostatic stress, lower body negative pressure(LBNP), while measuring cardiac output by inert gas rebreathing, regional blood volume, and regional blood flow using plethysmographic techniques focusing on splanchnic changes, and muscle sympathetic nerve activity by peroneal microneurography. We will study synaptic peripheral neurotransmission of Norepinephrine and how it is affected by supplemental NO and by nitric oxide synthase inhibitor.
Tracking Information
- NCT #
- NCT01791816
- Collaborators
- Not Provided
- Investigators
- Principal Investigator: Julian M. Stewart, M.D., Ph.D. New York Medical College