| Abstract: | Background: New technologies like echocardiography, color Doppler, CT, and MRI provide
more direct and accurate evidence of heart disease than heart auscultation. However, these
modalities are costly, large in size and operationally complex and therefore are not suitable for use
in rural areas, in homecare and generally in primary healthcare set-ups. Furthermore the majority
of internal medicine and cardiology training programs underestimate the value of cardiac
auscultation and junior clinicians are not adequately trained in this field. Therefore efficient decision
support systems would be very useful for supporting clinicians to make better heart sound
diagnosis. In this study a rule-based method, based on decision trees, has been developed for
differential diagnosis between "clear" Aortic Stenosis (AS) and "clear" Mitral Regurgitation (MR)
using heart sounds.
Methods: For the purposes of our experiment we used a collection of 84 heart sound signals
including 41 heart sound signals with "clear" AS systolic murmur and 43 with "clear" MR systolic
murmur. Signals were initially preprocessed to detect 1st and 2nd heart sounds. Next a total of
100 features were determined for every heart sound signal and relevance to the differentiation
between AS and MR was estimated. The performance of fully expanded decision tree classifiers and
Pruned decision tree classifiers were studied based on various training and test datasets. Similarly,
pruned decision tree classifiers were used to examine their differentiation capabilities. In order to
build a generalized decision support system for heart sound diagnosis, we have divided the problem
into sub problems, dealing with either one morphological characteristic of the heart-sound
waveform or with difficult to distinguish cases.
Results: Relevance analysis on the different heart sound features demonstrated that the most
relevant features are the frequency features and the morphological features that describe S1, S2
and the systolic murmur. The results are compatible with the physical understanding of the
problem since AS and MR systolic murmurs have different frequency contents and different
waveform shapes. On the contrary, in the diastolic phase there is no murmur in both diseases which results in the fact that the diastolic phase signals cannot contribute to the differentiation between AS and MR. |
|---|
Greek