What is the clinical evidence from this study?

Study design: Other. Population: healthy (n=15). Intervention: Graded head-up tilt. Primary outcome: Ventricular repolarization duration (VRD) variability.

What question did this study set out to answer?

To characterize ventricular repolarization duration variability across graded head-up tilt angles and decouple heart period and respiratory influences from intrinsic autonomic modulation.

February 12, 2010AJP Heart and Circulatory Physiology

RT variability unrelated to heart period and respiration progressively increases during graded head-up tilt

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Key result

Graded head-up tilt progressively increased RT variance, characterized by a gradual rise in RR-R-unrelated RT variability while RR-related RT variability remained unchanged.

Why the study?

Does graded head-up tilt alter ventricular repolarization duration variability in healthy humans?

Population

15 healthy humans, median age 28 years (range 24-54), 6 women and 9 men.

Comparison

Graded head-up tilt vs Different angles of tilt

Design

Other, Random order of tilt steps

Authors

APAlberto PortaElectrophysiology ETEleonora TobaldiniGeneral Cardiology TGTomaso Gnecchi‐RusconeImperial College Healthcare NHS Trust

Discussion

Member takes

Implication

May index ventricular sympathetic tone during orthostasis; hypothesis-generating for autonomic monitoring pending validation.

Key Points

To characterize ventricular repolarization duration variability across graded head-up tilt angles and decouple heart period and respiratory influences from intrinsic autonomic modulation.
Surface ECG and chest movements were recorded in 15 healthy adults (aged 24–54 years, median 28; 6 women, 9 men) during randomized head-up tilt angles from 15° to 90° in 15° increments.
Open-loop linear parametric models separated RT variability into heart period-related, respiration-related, and unrelated components using RT apex and RT end intervals.
Total RT variance progressively increased with tilt inclination, driven specifically by a rise in variability unrelated to heart period and respiration while rate-dependent variability remained unchanged.
Predictability of RT intervals decreased as tilt angle steepened, with RT end variability displaying greater complexity and a higher proportion of unrelated variability than RT apex.

Structured PICO

Does graded head-up tilt alter ventricular repolarization duration variability in healthy humans?

Population

15 healthy humans (median age 28 years, 40% female) undergoing graded head-up tilt testing.

Exposure

Graded head-up tilt (15 to 90 degrees in 15-degree steps, random order)

Comparator

Different angles of tilt (within-subject comparison)

Outcome

Ventricular repolarization duration (VRD) variability (RT variability)surrogate

RR-R-unrelated RT variability increases with sympathetic drive during head-up tilt and may serve as an indirect measure of autonomic regulation directed to the ventricles.

Cite This Study

Porta et al. (2010) studied healthy (n=15). Graded head-up tilt was evaluated on Ventricular repolarization duration (VRD) variability. Graded head-up tilt progressively increased RT variance, characterized by a gradual rise in RR-R-unrelated RT variability while RR-related RT variability remained unchanged.

synapsesocial.com/papers/6a7dad5be5379bb2b27d881a https://doi.org/10.1152/ajpheart.01206.2009

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RT variability unrelated to heart period and respiration progressively increases during graded head-up tilt

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

RT variability unrelated to heart period and respiration progressively increases during graded head-up tilt

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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