Mindray ePM 10M, Operator'S Manual

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F - 1
F
A ECG Wave Recognition Method for Mindray
Resting 12-lead ECG Analysis Algorithm
F.1 Preprocessing
Initially, a 50Hz or 60Hz notch filter should have been applied within the acquiring device. The ECG data is then
filtered to minimize the effects of noise. The next step is to calculate a difference of each lead. And then choose
the best 3 leads based on the amplitude of ECG. Combining the ECG data and the difference in these best 3
leads, the QRS locations are derived.
F.2 QRS typing
For each lead, the QRS complexes is compared each other, if the QRS width, RR Interval, and the morphology of
QRS complex are similar, the QRS complexes are classified to the same class. Synthesizing QRS class of all the 12
leads, the beats are classified to different classes.
F.3 Selection of required QRS class
If more than one class of beat is present, then a decision has to be made as to which morphology will be used for
the averaging procedure. A complex logic is used and the required QRS class is regarded as being conducted in
the normal sequence through the ventricles.
F.4 Averaging
All beats in the selected class are averaged. First the alignment points are detected, and then all corresponding
aligned points are straight averaged.
F.5 Wave measurement
From the 12 average beats, first the peak of QRS is determined, and then considering the amplitude and the
slope, the QRS onset and termination are determined.
In each individual lead, the QRS onset is taken as the baseline and hence Q, R, S, R’ waves are measured with
respect to the QRS onset.
A sorting algorithm is then applied to all 12 onsets to determine the global QRS onset as follows. The two earliest
onsets are excluded and the next onset that also lies within 10ms of two before that is then selected as the
overall onset. The reverse process is used to find the overall QRS termination but the interval limit is changed
from 10ms to 16ms. The isoelectric segment at the beginning of a QRS complex which is a flat segment between
the globe QRS onset and individual lead QRS onset are exclude from the first component of the QRS, the same
process is used for the isoelectric segment at the end of a QRS complex.
F.6 QRS components
Within the QRS complex, the amplitude and duration of the various Q, R, S, R’ waves are then measured. In
keeping with the CSE recommendations, the minimum wave acceptable has to have a duration >8 ms and an
amplitude >20 ?V. The global QRS duration is from global QRS onset to the global QRS termination.
F.7 ST segment
The ST segment measurements are made at J point, and at equal intervals throughout the ST segment.