Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt

Farah A. Ramirez-Marrero, Nisha Charkoudian, Emma C. Hart, Darrell Schroeder, Liu Zhong, John H. Eisenach, Michael Joseph Joyner

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Orthostatic stress such as head-up tilt (HUT) elicits a wide range of heart rate (HR) and arterial pressure (AP) responses among healthy individuals. In this study, we evaluated cardiovascular dynamics in healthy subjects with different HR responses to HUT, but without autonomic dysfunction. We measured AP (brachial artery) and HR (ECG) during 5 min of 60° HUT in 76 healthy normotensive individuals. We then chose individuals on the basis of the extremes of HR responses to HUT (high = ΔHR ≥ 20 beats/min, and low = ΔHR ≤ 10 beats/min; n = 15 per group). Peak HR during HUT was 87 ± 10 beats/min in the high and 69 ± 14 beats/min in the low group (P < 0.05). High HR responders had lower systolic pressure at baseline (121 ± 9 vs. 129 ± 11 mmHg, P < 0.05) and during HUT (120 ± 10 vs. 131 ± 13 mmHg, P < 0.05), and higher plasma norepinephrine (NE) response to HUT (ΔNE: 156.9 ± 17.8 vs. 89.0 ± 17.2 pg/ml; P < 0.05). ΔNE during HUT was also significantly correlated with ΔHR when all 76 subjects were included in a regression analysis (r = 0.39; P < 0.001). Pulse pressure was lower during HUT in high HR responders compared with low HR responders (45 ± 1 vs. 55 ± 2 mmHg, P < 0.05). High HR responders also had larger fluctuations in systolic and pulse pressure during HUT (coefficient of variation = 10.7 ± 0.7 vs. 5.7 ± 0.3%; 7.9 ± 0.5 vs. 4.1 ± 0.4%, respectively, P < 0.05). Sex distribution was different between groups (high: 5 women, 10 men; low: 10 women, 5 men). Higher HR with lower AP during HUT is consistent with normal baroreflex mechanisms of integration. Although interindividual variability appears to be a fundamental part of cardiovascular regulation, the mechanisms of these differences and the sex discrepancy requires further investigation.

Original languageEnglish (US)
Pages (from-to)1448-1453
Number of pages6
JournalJournal of Applied Physiology
Volume105
Issue number5
DOIs
StatePublished - Nov 2008

Fingerprint

Healthy Volunteers
Heart Rate
Head
Blood Pressure
Norepinephrine
Arterial Pressure
Sex Distribution
Brachial Artery
Baroreflex
Sex Characteristics
Electrocardiography
Regression Analysis

Keywords

  • Arterial pressure
  • Baroreflex
  • Norepinephrine
  • Orthostasis
  • Sympathetic nervous system

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Ramirez-Marrero, F. A., Charkoudian, N., Hart, E. C., Schroeder, D., Zhong, L., Eisenach, J. H., & Joyner, M. J. (2008). Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt. Journal of Applied Physiology, 105(5), 1448-1453. https://doi.org/10.1152/japplphysiol.90796.2008

Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt. / Ramirez-Marrero, Farah A.; Charkoudian, Nisha; Hart, Emma C.; Schroeder, Darrell; Zhong, Liu; Eisenach, John H.; Joyner, Michael Joseph.

In: Journal of Applied Physiology, Vol. 105, No. 5, 11.2008, p. 1448-1453.

Research output: Contribution to journalArticle

Ramirez-Marrero, FA, Charkoudian, N, Hart, EC, Schroeder, D, Zhong, L, Eisenach, JH & Joyner, MJ 2008, 'Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt', Journal of Applied Physiology, vol. 105, no. 5, pp. 1448-1453. https://doi.org/10.1152/japplphysiol.90796.2008
Ramirez-Marrero FA, Charkoudian N, Hart EC, Schroeder D, Zhong L, Eisenach JH et al. Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt. Journal of Applied Physiology. 2008 Nov;105(5):1448-1453. https://doi.org/10.1152/japplphysiol.90796.2008
Ramirez-Marrero, Farah A. ; Charkoudian, Nisha ; Hart, Emma C. ; Schroeder, Darrell ; Zhong, Liu ; Eisenach, John H. ; Joyner, Michael Joseph. / Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt. In: Journal of Applied Physiology. 2008 ; Vol. 105, No. 5. pp. 1448-1453.
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N2 - Orthostatic stress such as head-up tilt (HUT) elicits a wide range of heart rate (HR) and arterial pressure (AP) responses among healthy individuals. In this study, we evaluated cardiovascular dynamics in healthy subjects with different HR responses to HUT, but without autonomic dysfunction. We measured AP (brachial artery) and HR (ECG) during 5 min of 60° HUT in 76 healthy normotensive individuals. We then chose individuals on the basis of the extremes of HR responses to HUT (high = ΔHR ≥ 20 beats/min, and low = ΔHR ≤ 10 beats/min; n = 15 per group). Peak HR during HUT was 87 ± 10 beats/min in the high and 69 ± 14 beats/min in the low group (P < 0.05). High HR responders had lower systolic pressure at baseline (121 ± 9 vs. 129 ± 11 mmHg, P < 0.05) and during HUT (120 ± 10 vs. 131 ± 13 mmHg, P < 0.05), and higher plasma norepinephrine (NE) response to HUT (ΔNE: 156.9 ± 17.8 vs. 89.0 ± 17.2 pg/ml; P < 0.05). ΔNE during HUT was also significantly correlated with ΔHR when all 76 subjects were included in a regression analysis (r = 0.39; P < 0.001). Pulse pressure was lower during HUT in high HR responders compared with low HR responders (45 ± 1 vs. 55 ± 2 mmHg, P < 0.05). High HR responders also had larger fluctuations in systolic and pulse pressure during HUT (coefficient of variation = 10.7 ± 0.7 vs. 5.7 ± 0.3%; 7.9 ± 0.5 vs. 4.1 ± 0.4%, respectively, P < 0.05). Sex distribution was different between groups (high: 5 women, 10 men; low: 10 women, 5 men). Higher HR with lower AP during HUT is consistent with normal baroreflex mechanisms of integration. Although interindividual variability appears to be a fundamental part of cardiovascular regulation, the mechanisms of these differences and the sex discrepancy requires further investigation.

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