Healthc Inform Res.  2018 Jul;24(3):198-206. 10.4258/hir.2018.24.3.198.

Electrocardiogram Sampling Frequency Range Acceptable for Heart Rate Variability Analysis

• Kwon O
• Jeong J
• Kim HB
• Kwon IH
• Park SY
• Kim JE
• Choi Y

• KMID: 2418170
• DOI: http://doi.org/10.4258/hir.2018.24.3.198

Abstract

OBJECTIVES
Heart rate variability (HRV) has gained recognition as a noninvasive marker of autonomic activity. HRV is considered a promising tool in various clinical scenarios. The optimal electrocardiogram (ECG) sampling frequency required to ensure sufficient precision of R-R intervals for HRV analysis has not yet been determined. Here, we aimed to determine the acceptable ECG sampling frequency range by analyzing ECG signals from patients who visited an emergency department with the chief complaint of acute intoxication or overdose.
METHODS
The study included 83 adult patients who visited an emergency department with the chief complaint of acute poisoning. The original 1,000-Hz ECG signals were down-sampled to 500-, 250-, 100-, and 50-Hz sampling frequencies with linear interpolation. R-R interval data were analyzed for time-domain, frequency-domain, and nonlinear HRV parameters. Parameters derived from the data on down-sampled frequencies were compared with those derived from the data on 1,000-Hz signals, and Lin's concordance correlation coefficients were calculated.
RESULTS
Down-sampling to 500 or 250 Hz resulted in excellent concordance. Signals down-sampled to 100 Hz produced acceptable results for time-domain analysis and Poincaré plots, but not for frequency-domain analysis. Down-sampling to 50 Hz proved to be unacceptable for both time- and frequency-domain analyses. At 50 Hz, the root-mean-squared successive differences and the power of high frequency tended to have high values and random errors.
CONCLUSIONS
A 250-Hz sampling frequency would be acceptable for HRV analysis. When frequency-domain analysis is not required, a 100-Hz sampling frequency would also be acceptable.

Keyword

Electrocardiography; Heart Rate; Computer-Assisted Signal Processing; Poisoning; Emergencies

MeSH Terms

Adult
Electrocardiography*
Emergencies
Emergency Service, Hospital
Heart Rate*
Heart*
Humans
Poisoning
Signal Processing, Computer-Assisted

Figure

• 

  Figure 1 Scatterplot of the root-mean-squared successive differences (RMSSD) derived from down-sampled electrocardiography recordings in comparison with those from 1,000-Hz signals: (A) 500 Hz, (B) 250 Hz, (C) 100 Hz, and (D) 50 Hz. Lines of equity and regression lines are also displayed.

• 

  Figure 2 Scatterplot of the low-frequency (LF) power spectral density derived from down-sampled electrocardiography recordings in comparison with those from 1,000-Hz signals: (A) 500 Hz, (B) 250 Hz, (C) 100 Hz, and (D) 50 Hz. Lines of equity and regression lines are also displayed.

• 

  Figure 3 Scatterplot of the high-frequency (HF) power spectral density derived from down-sampled electrocardiography recordings in comparison with those from 1,000-Hz signals: (A) 500 Hz, (B) 250 Hz, (C) 100 Hz, and (D) 50 Hz. Lines of equity and regression lines are also displayed.

• 

  Figure 4 Bland-Altman plots of agreement between heart rate variability parameters from 100-Hz down-sampled signals and those from 1,000-Hz signals: (A) root-mean-squared successive differences (RMSSD), (B) proportion of NN50 to total number of R–R intervals (pNN50), (C) power of very low frequency (VLF), (D) power of low frequency (LF), (E) power of high frequency (HF), (F) Poincaré plot width, and (G) Poincaré plot length. Lines and values indicating 95% limits of agreement are presented.

• 

  Figure 5 Electrocardiograms of single cardiac cycle and onset of QRS complexes detected by the gqrs command in Physio-Toolkit from various sampling frequencies. (A) 1,000 Hz, (B) 250 Hz, (C) 100 Hz, and (D) 50 Hz.

• 

  Figure 6 R–R interval series graph from electrocardiography recordings sampled at frequencies of (A) 1,000 Hz and (B) 50 Hz. Loss of detailed information of R–R intervals is noted.

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