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A novel heart rate control model provides insights linking LF-HRV behavior to the open-loop gain.
MedLine Citation:
PMID:  23063210     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
BACKGROUND: Low-frequency heart rate variability (LF-HRV) at rest has already been successfully modeled as self-sustained oscillations in a nonlinear control loop, but these models fail to simulate LF-HRV decreases either during aerobic exercise or in heart failure patients. Following control engineering practices, we assume the existence of a biological excitation (dither) within the heart rate control loop that softens the nonlinearity and studied LF-HRV behavior in a dither-embedded model. METHODS: We adopted the Ottesen model with some revisions and induced a dither of high-frequency stochastic perturbations. We simulated scenarios of a healthy subject at rest and during aerobic exercise (by decreasing peripheral vascular resistance) and a heart failure patient (by decreasing stroke volume). RESULTS: The simulations resembled physiological LF-HRV behavior, i.e., LF-HRV decreased during aerobic exercise and in the heart failure patient. The simulations exhibited LF-HRV dependency on the open-loop gain, which is related to the product of the feedback gain and the feed forward gain. CONCLUSIONS: We are the first to demonstrate that LF-HRV may be dependent on the open-loop gain. Accordingly, reduced open-loop gain results in decreased LF-HRV, and vice versa. Our findings explain a well-known but unexplained observed phenomenon of reduced LF-HRV both in heart failure patients and in healthy subjects performing aerobic exercise. These findings have implications on how changes in LF-HRV can be interpreted physiologically, a necessary step towards the clinical utilization of LF-HRV.
Authors:
Hila Dvir; Ben Zion Bobrovsky; Uri Gabbay
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-10
Journal Detail:
Title:  International journal of cardiology     Volume:  -     ISSN:  1874-1754     ISO Abbreviation:  Int. J. Cardiol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8200291     Medline TA:  Int J Cardiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Affiliation:
School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel.
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