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294 Appendix A. CD Datasets

DP prolonged decelerations DR repetitive decelerations
WIDTH histogram width (histogram of foetal heart rate values)
MIN low freq. of the histogram MAX high freq. of the histogram
NMAX number of histogram peaks NZER number of histogram zeros
MODE histogram mode MEAN histogram mean
MEDIAN histogram median VAR histogram variance
TEND histogram tendency: -l=left assym.; O=symm.; l=right assym.

The data is classified into ten classes:

A calm sleep
B rapid eye movement sleep
C calm vigilance
D active vigilance
SH shift pattern (A or SUSP with shifts)
AD accelerativeldecelerative pattern (stress situation)
DE decelerative pattern (vagal stimulation)
LD largely decelerative pattern
FS flat-sinusoidal pattern (pathological state)
SUSP suspect pattern

A column containing the codes of Normal (I), Suspect (2) and Pathologic (3)
classification is also included.

Source: J Bernardes, Faculty of Medicine, Oporto University.
Reference: D Ayres de Campos et al. (2000) SisPorto 2.0 A Program for
Automated Analysis of Cardiotocograms. J Matem Fetal Med 5:3 11-318.

A.6 Electrocardiograms

The ECG Signals.xls file contains seven electrocardiographic signals (ECG)
acquired at S. Jo5o Hospital, Oporto. An ECG records the electrical activity of the
heart. Its amplitude is measured in microvolts and is represented along a column of
the Microsoft Excel file, sampled at f,=250Hz (250 signal rows represent 1
second).
All seven ECG tracings have 5 second durations and basically consist of the
repetition of wave packets in correspondence with the atrial and ventricular
activities as mentioned in section 1.3 (Figure 1.9):

- P wave: reflects the atrial activity. P waves can be unipolar, positive or negative,
or bipolar (positive followed by negative or vice-versa).
- Q, R, S waves: a sequence of high slope negative, positive, negative waves,
reflecting the ventricular polarisation. Some of these waves can be absent: an
ECG can contain only QR, QS, RS, R or Q sequences.