Biomedical Engineering Reference
In-Depth Information
Table 5.3 Compression results with mit-db data
Patient file ID in PhysioNet with lead number
CR
PRD
QS
100-v5
22.68
3.225
7.032
101-v1
17.85
1.685
10.59
102-v2
18.02
0.782
23.04
103-v2
22.68
5.626
4.031
104-v2
21.73
3.601
6.034
To assess the preservation of clinical features in the decompressed data, a new
set of clinical signatures, named diagnostic distortion factors (DDF), are intro-
duced [ 37 ]. These clinical signatures, listed below, are specified from the ECG
wave which is essential to be preserved before compression and after recon-
struction. These are as follows:
RR i
RR interval;
QRS dur
QRS duration;
QT int
QT interval;
P dur
P width;
R amp
R amplitude;
P amp
P amplitude;
T amp
T amplitude;
S amp
S amplitude
The DDF parameter provides a beat-to-beat variation of the feature being
investigated, averaged over all cardiac cycles in the dataset. It is estimated with the
following formula:
DDF f ¼ P i ¼ 1 f i f r
n
100
ð 5 : 15 Þ
where
n
Total number of complete beats transmitted
f i
Value of signature before compression
f r
Value of signature after reconstruction
For a number of the ptb-db and mit-db data files, the DDF parameters are
estimated by both manually and using separate algorithms. Table 5.4 provides an
estimate of these DDF parameters, computed over all beats, over the 90 normal
and 10 abnormal leads from ptb-db data.
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