Key result
Orthostatic intolerance in young female patients was associated with increased mechanical modulation and neural baroreflex, and decreased respiratory sinus arrhythmia during a head-up tilt test.
Why the study?
Extended partial directed coherence was applied to establish the temporal dynamic behavior of cardiovascular and cardiorespiratory interactions during orthostatic stress during a 70° head-up tilt test.
Does extended partial directed coherence (ePDC) analysis during a 70° head-up tilt test reveal altered cardiovascular and cardiorespiratory interactions in patients with orthostatic intolerance compared to healthy controls?
Observational
Does extended partial directed coherence (ePDC) analysis during a 70° head-up tilt test reveal altered cardiovascular and cardiorespiratory interactions in patients with orthostatic intolerance compared to healthy controls?
Extended partial directed coherence analysis during head-up tilt testing reveals impaired cardiovascular and cardiorespiratory interactions in patients with orthostatic intolerance.
May inform autonomic phenotyping in OI; leaves open standardization before clinical adoption.
In this study, the linear method of extended partial directed coherence (ePDC) was applied to establish the temporal dynamic behavior of cardiovascular and cardiorespiratory interactions during orthostatic stress at a 70° head-up tilt (HUT) test on young age-matched healthy subjects and patients with orthostatic intolerance (OI), both male and female. Twenty 5-min windows were used to analyze the minute-wise progression of interactions from 5 min in a supine position (baseline, BL) until 18 min of the orthostatic phase (OP) without including pre-syncopal phases. Gender differences in controls were present in cardiorespiratory interactions during OP without compromised autonomic regulation. However in patients, analysis by ePDC revealed considerable dynamic alterations within cardiovascular and cardiorespiratory interactions over the temporal course during the HUT test. Considering the young female patients with OI, the information flow from heart rate to systolic blood pressure (mechanical modulation) was already increased before the tilt-up, the information flow from systolic blood pressure to heart rate (neural baroreflex) increased during OP, while the information flow from respiration to heart rate (respiratory sinus arrhythmia) decreased during the complete HUT test. Findings revealed impaired cardiovascular interactions in patients with orthostatic intolerance and confirmed the usefulness of ePDC for causality analysis.
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Charleston-Villalobos et al. (2019) conducted an observational in Orthostatic intolerance. Orthostatic intolerance vs. Healthy subjects was evaluated on Temporal dynamic behavior of cardiovascular and cardiorespiratory interactions. Orthostatic intolerance in young female patients was associated with increased mechanical modulation and neural baroreflex, and decreased respiratory sinus arrhythmia during a head-up tilt test.
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