LifeWatch ECG Mini, User Manual, Page: 42 / 59

Page 42
8 HEART RATE CALCULATION METHOD
8.1 Introduction
This section describes the Heart Rate (HR) calculation within the ECG
Mini. HR is defined as the number of heart beats during a GIVEN TIME
INTERVAL (usually one minute). It is reported by the algorithm each time a
QRS complex is detected.
8.2 Method of Calculation
The momentary HR is the inverse of the time lasting between two
consecutive heart beats. As the momentary HR fluctuates due to
inaccuracies in detecting the exact R wave timing eight momentary HR
values are averaged to generate the displayed HR. Therefore the reported
HR is the mean of the last momentary HR values WHICH CORRESPOND
TO THE DETECTED R COMPLEXES FOR THE LAST 8 SECONDS.
OCCASIONS IN WHICH THE HR IS NOT REPORTED: If during a specific
QRS complex the signal is considered as too low to be considered
accurate or is considered as noise, the displayed HR will be 0.
9 PAUSE CALCULATION
Pause is considered a lack of Ventricular activity for more than 3 seconds.
In order to detect a pause one of two conditions needs to be detected:
1. Lack of QRS detection for more than 3 seconds
2. A flat signal (P complexes can occur) for slightly less than 3
seconds.
Once one of the above conditions is detected a pause event is called.