Key result
Head-down tilt reduced the involvement of the baroreflex in governing heart period and systolic arterial pressure dynamic interactions in the low frequency band.
Why the study?
The study was conducted to typify directional dynamic interactions between heart period and systolic arterial pressure during baroreflex loading induced by head-down tilt using frequency domain causality analysis.
Does head-down tilt alter the directional dynamic interactions between heart period and systolic arterial pressure in healthy men?
Observational (n=12)
Does head-down tilt alter the directional dynamic interactions between heart period and systolic arterial pressure in healthy men?
Head-down tilt reduces the relevance of baroreflex control in governing heart period and systolic arterial pressure interactions in the low frequency band, allowing investigation of other cardiovascular regulatory mechanisms.
Enables probing of non-baroreflex cardiovascular regulation; leaves open relevance beyond healthy subjects.
Frequency domain causality analysis based on multivariate autoregressive (MAR) and multivariate dynamic adjustment (MDA) models were applied to typify directional dynamic interactions between heart period (HP) and systolic arterial pressure (SAP) during the baroreflex loading induced by head-down tilt (HDT). We studied 12 healthy men (age: from 41 to 71 yrs, median: 57 yrs) at rest in supine condition and during HDT with a tilt table inclination equal to −25°. We observed a reduction of the involvement of the baroreflex in governing HP-SAP dynamic interactions during HDT. This finding was evident only in the low frequency (LF, from 0.04 to 0.15 Hz) band. We suggest that frequency domain causality analysis allows the investigation of cardiovascular control mechanisms and HDT can be fruitfully utilized to reduce the relevance of baroreflex control, thus raising the chance of observing different cardiovascular regulatory mechanisms.
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Porta et al. (2022) conducted an observational in Healthy (n=12). Head-down tilt (HDT) vs. Rest in supine condition was evaluated on Directional dynamic interactions between heart period (HP) and systolic arterial pressure (SAP). Head-down tilt reduced the involvement of the baroreflex in governing heart period and systolic arterial pressure dynamic interactions in the low frequency band.
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