Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability

Alberto Porta, Eleonora Tobaldini, Stefano Guzzetti, Raffaello Furlan, Nicola Montano, Tomaso Gnecchi-Ruscone

Research output: Contribution to journalArticle

Abstract

Two symbolic indexes, the percentage of sequences characterized by three heart periods with no significant variations (0V%) and that with two significant unlike variations (2UV%), have been found to reflect changes in sympathetic and vagal modulations, respectively. We tested the hypothesis that symbolic indexes may track the gradual shift of the cardiac autonomic modulation during an incremental head-up tilt test. Symbolic analysis was carried out over heart period variability series (250 cardiac beats) derived from ECG recordings during a graded head-up tilt test (0, 15, 30, 45, 60, 75, and 90° ) in 17 healthy subjects. The percentage of subjects showing a significant linear correlation (Spearman rank-order correlation) with tilt angles was utilized to evaluate the performance of symbolic analysis. Spectral analysis was carried out for comparison over the same series. 0V% progressively increased with tilt angles, whereas 2UV% gradually decreased. The decline of 2UV% was greater than the increase of 0V% at low tilt angles. Linear correlation with tilt angles was exhibited in a greater percentage of subjects for 0V% and 2UV% than for any spectral index. Our findings suggest that symbolic analysis performed better than spectral analysis and, thus, is a suitable methodology for assessment of the subtle changes of cardiac autonomic modulation induced by a graded head-up tilt test. Moreover, symbolic analysis indicates that the changes of cardiac sympathetic and vagal modulations observed during this protocol were reciprocal but characterized by different absolute magnitudes.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume293
Issue number1
DOIs
Publication statusPublished - Jul 2007

Fingerprint

Heart Rate
Head
Healthy Volunteers
Electrocardiography

Keywords

  • Autonomic nervous system
  • Power spectral density

ASJC Scopus subject areas

  • Physiology

Cite this

@article{51c78b311adc4bb79fb318ad15d03696,
title = "Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability",
abstract = "Two symbolic indexes, the percentage of sequences characterized by three heart periods with no significant variations (0V{\%}) and that with two significant unlike variations (2UV{\%}), have been found to reflect changes in sympathetic and vagal modulations, respectively. We tested the hypothesis that symbolic indexes may track the gradual shift of the cardiac autonomic modulation during an incremental head-up tilt test. Symbolic analysis was carried out over heart period variability series (250 cardiac beats) derived from ECG recordings during a graded head-up tilt test (0, 15, 30, 45, 60, 75, and 90° ) in 17 healthy subjects. The percentage of subjects showing a significant linear correlation (Spearman rank-order correlation) with tilt angles was utilized to evaluate the performance of symbolic analysis. Spectral analysis was carried out for comparison over the same series. 0V{\%} progressively increased with tilt angles, whereas 2UV{\%} gradually decreased. The decline of 2UV{\%} was greater than the increase of 0V{\%} at low tilt angles. Linear correlation with tilt angles was exhibited in a greater percentage of subjects for 0V{\%} and 2UV{\%} than for any spectral index. Our findings suggest that symbolic analysis performed better than spectral analysis and, thus, is a suitable methodology for assessment of the subtle changes of cardiac autonomic modulation induced by a graded head-up tilt test. Moreover, symbolic analysis indicates that the changes of cardiac sympathetic and vagal modulations observed during this protocol were reciprocal but characterized by different absolute magnitudes.",
keywords = "Autonomic nervous system, Power spectral density",
author = "Alberto Porta and Eleonora Tobaldini and Stefano Guzzetti and Raffaello Furlan and Nicola Montano and Tomaso Gnecchi-Ruscone",
year = "2007",
month = "7",
doi = "10.1152/ajpheart.00006.2007",
language = "English",
volume = "293",
journal = "American Journal of Physiology",
issn = "0363-6119",
publisher = "American Physiological Society",
number = "1",

}

TY - JOUR

T1 - Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability

AU - Porta, Alberto

AU - Tobaldini, Eleonora

AU - Guzzetti, Stefano

AU - Furlan, Raffaello

AU - Montano, Nicola

AU - Gnecchi-Ruscone, Tomaso

PY - 2007/7

Y1 - 2007/7

N2 - Two symbolic indexes, the percentage of sequences characterized by three heart periods with no significant variations (0V%) and that with two significant unlike variations (2UV%), have been found to reflect changes in sympathetic and vagal modulations, respectively. We tested the hypothesis that symbolic indexes may track the gradual shift of the cardiac autonomic modulation during an incremental head-up tilt test. Symbolic analysis was carried out over heart period variability series (250 cardiac beats) derived from ECG recordings during a graded head-up tilt test (0, 15, 30, 45, 60, 75, and 90° ) in 17 healthy subjects. The percentage of subjects showing a significant linear correlation (Spearman rank-order correlation) with tilt angles was utilized to evaluate the performance of symbolic analysis. Spectral analysis was carried out for comparison over the same series. 0V% progressively increased with tilt angles, whereas 2UV% gradually decreased. The decline of 2UV% was greater than the increase of 0V% at low tilt angles. Linear correlation with tilt angles was exhibited in a greater percentage of subjects for 0V% and 2UV% than for any spectral index. Our findings suggest that symbolic analysis performed better than spectral analysis and, thus, is a suitable methodology for assessment of the subtle changes of cardiac autonomic modulation induced by a graded head-up tilt test. Moreover, symbolic analysis indicates that the changes of cardiac sympathetic and vagal modulations observed during this protocol were reciprocal but characterized by different absolute magnitudes.

AB - Two symbolic indexes, the percentage of sequences characterized by three heart periods with no significant variations (0V%) and that with two significant unlike variations (2UV%), have been found to reflect changes in sympathetic and vagal modulations, respectively. We tested the hypothesis that symbolic indexes may track the gradual shift of the cardiac autonomic modulation during an incremental head-up tilt test. Symbolic analysis was carried out over heart period variability series (250 cardiac beats) derived from ECG recordings during a graded head-up tilt test (0, 15, 30, 45, 60, 75, and 90° ) in 17 healthy subjects. The percentage of subjects showing a significant linear correlation (Spearman rank-order correlation) with tilt angles was utilized to evaluate the performance of symbolic analysis. Spectral analysis was carried out for comparison over the same series. 0V% progressively increased with tilt angles, whereas 2UV% gradually decreased. The decline of 2UV% was greater than the increase of 0V% at low tilt angles. Linear correlation with tilt angles was exhibited in a greater percentage of subjects for 0V% and 2UV% than for any spectral index. Our findings suggest that symbolic analysis performed better than spectral analysis and, thus, is a suitable methodology for assessment of the subtle changes of cardiac autonomic modulation induced by a graded head-up tilt test. Moreover, symbolic analysis indicates that the changes of cardiac sympathetic and vagal modulations observed during this protocol were reciprocal but characterized by different absolute magnitudes.

KW - Autonomic nervous system

KW - Power spectral density

UR - http://www.scopus.com/inward/record.url?scp=34547100763&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547100763&partnerID=8YFLogxK

U2 - 10.1152/ajpheart.00006.2007

DO - 10.1152/ajpheart.00006.2007

M3 - Article

C2 - 17308016

AN - SCOPUS:34547100763

VL - 293

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6119

IS - 1

ER -