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RMSSD for HRV Analysis

ECG Data

Root Mean Square of the Successive Differences (RMSSD) is one of a few time-domain tools used to assess heart rate variability, the successive differences being neighboring RR intervals. The automated analysis routine in AcqKnowledge® will perform the analysis within fixed time intervals, between event boundaries (user defined event marks), and focus areas within the data. The software will either paste the data into a journal file or a spreadsheet for further analysis.

Use AcqKnowledge‘s Multi-epoch HRV – Statistical analysis routine to automate RMSSD, SDSD, and pNN50 HRV calculations. There is also an additional script option to perform the same analysis – Script 056: Compute HRV Statistics.

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Figure 1 R-R interval

Figure 1 shows the R-R intervals labeled A = (R-R)1, B = (R-R)2, C = (R-R)3, …. (R-R)i represents the interval between two neighboring QRS peaks.
The RMSSD is looking for the successive difference between the intervals meaning:

A-B à(R-R)1 – (R-R)2
B-C à(R-R)2 – (R-R)3…and so forth

The RMSSD calculates to:

RMSSD = RMSSD formula

where N = number of RR interval terms

HRV Statistical

Using the option to export the HRV tachogram to Excel, the calculation of the RMSSD is structured in Excel to appear as shown in Figure 2:HRV Statistics

Figure 2 Excel sheet for RMSSD calculation



BIOPAC Research Solutions | ECG


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