Heart rate variability: for real doctors. Translation from the Russian version of the book, published at Kharkiv, 2010, 131 p.
The basics and practice of the clinical use of the technology of heart rate variability are outlined for doctors of all specialties and students of medical faculties of universities.
Methods and indicators of the HRV of the time domain (Time Domain Methods)
The following indicators are determined for a rhythmogram (a segment (a dedicated part) of a rhythmogram):
MHR — average heart rate,
SDNN — standard deviation of the average duration of regular RR intervals (NN-intervals),
SDANN — standard deviation of SDNN values from 5 (10) -minute segments for the average period, hours-long or 24-hour records,
RMSSD is the square root of the sum of squares of the difference in the values of consecutive pairs of NN-intervals,
NN5O is the number of pairs of successive NN-intervals for the entire period of B differing by more than 50 milliseconds,
PNN5O – the percentage of total NN50 number successive pairs of NN-intervals which differ by more than 50 milliseconds, obtained for the entire recording period, VAR – variation coefficient NN-intervals.
Indicators of heart rate variability of the time domain are summarized in Table. 2.1.
Most of the indicators of the HRV of the time domain strongly correlate with each other, and for practical purposes, it suffices to limit oneself to two of them.
Our recommendations – use the indicators VAR and PNN5O. Only these two indicators are normalized to the duration of RR – intervals (HR), and therefore do not depend on their magnitude (invariants relative to their significance) and can be compared in the same subject at different stages and different research conditions.