Table of Contents Author Guidelines Submit a Manuscript
Modelling and Simulation in Engineering
Volume 2012 (2012), Article ID 931943, 8 pages
Research Article

SDNN/RMSSD as a Surrogate for LF/HF: A Revised Investigation

Department of Electrical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

Received 6 April 2012; Accepted 13 June 2012

Academic Editor: Laurent Mevel

Copyright © 2012 Hui-Min Wang and Sheng-Chieh Huang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Thousands of papers involved in heart rate variability (HRV). However, little was known about one important measure of HRV, the root mean square of successive heartbeat interval differences (RMSSDs). Another fundamental measure SDNN indicates standard deviation of normal to normal R-R intervals, where R is the peak of a QRS complex (heartbeat). Compared with SDNN, RMSSD is a short-term variation of heart rate. Through a time-frequency transformation, the ratio of low- and high-frequency power LF/HF represents the sympatho-vagal balance of the autonomic nervous system (ANS). Some research claimed that SDNN/RMSSD was a good surrogate for LF/HF. However, only two special cases supported this hypothesis in the literature survey. The first happened in resting supine state and the other was a group of prefrontal cortex patients. Both of their Pearson correlation coefficients reached 0.90, a reasonable criterion. In our study, a 6-week experiment was performed with 32 healthy young Asian males. The Pearson correlation coefficients had a normal distribution with average values smaller than 0.6 for 3 and 5-minute epochs, respectively. Our findings suggest this surrogate aspect could remain as a hypothesis.