between S and T (ST), segment T which presents from the beginning of wave T until
its end (T), and finally the segment between T and P from the next heartbeat (TP).
In addition, it is considered a set of intervals with clinical relevance. The intervals
considered are the PR interval, which is the combination of the P and PQ segments.
The PQ interval is similar to the former is the addition of the segments QS, ST and T.
Finally, the QRS interval coincides with QS segment, which is calculated for the
reconstruction. You can distinguish these intervals in the Fig. 1.
Thereby, this analysis can be carried out directly over the reconstruction parame-
ters, and consequently this does not require a more complex analysis. The described
intervals, theirs respective amplitudes and polarities are evaluated following the next
rules, which determine the possibility of that patient suffers of some arrhythmia or
cardiological diseases [10]:
• interval QRS > 0.12 secs Ventricular hypertrophy, necrosis, BCRD,
BCRI, pacemakers, cardiomyopathies, electrolyte abnormalities.
• Sign U <> Sign T Ischemic heart disease, hypokalaemia.
• interval PR > 0.20 secs First-degree AV block.
• interval PR < 0.12 secs Tachycardia, WPW, manners or headphones low rates.
• interval QT > 0.45 secs Antiarrhythmic medicines, ischemic heart
disease, cardiomyopathies, hypocalcemia, mixedema, long QT syndrome.
• interval QT < 0.35 secs hypercalcemia, hyperkalemia, early
repolarization, digoxin.
5 Communication Model Optimized for NFC
The data collected from the ECG module presented in Section IV can be transmitted
directly, where approximately 250 to 300 bytes are required to transmit every beat.
This direct transmission means a high overload and impact in the quality of service
(delay and latency) and lifetime of the personal device. For that reason, it is defined
an optimized communication model for NFC, in order to increase the lifetime of the
system and considering the requirements of a personal system of this kind should
reach a duration greater than hours, even days. The communication model considered
to perform the pre-processed is the YOAPY module [6]. YOAPY has been already
used with 6LoWPAN technology and offer a suitable solution to reduce dramatically
the number of bytes required to transmit for each heartbeat.
The pre-processing and compression of an ECG trace are methods and techniques
investigated throughout the literature. Some of the most relevant studies are based on
methods based on “wavelet”, which achieves compression of about 18:1 [11]. These
methods are focused on the complex formed by the QRS, which is the group of waves
that are marked on the signal from the wave of the electrocardiogram. The QRS com-
plex contains more clinically relevant data from the cardiology point of view. This
will determine whether the patient´s condition is normal, or is occurring abnormality
(arrhythmia) in the patient´s heart. Fig. 1 has shown the identification of the QRS
complex and the other significant points in the captured waveform from the module
shown in Fig. 2. The problem encountered is that wavelet-based methods are not
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