Screening for heart murmurs in children is an area of healthcare in which significant gains can be made in terms of efficiency. Due to diagnostic uncertainties in primary healthcare, heart murmurs, most of which are innocent, are the most common reason for referrals to a paediatric cardiologist. The phonocardiographic system, updated with current technology, could provide the additional information necessary to screen for heart murmurs in children reliably. In this thesis a prototype of a phonocardiographic system for non-cardiologist use was developed and its applicability to screening for heart murmurs in children was evaluated. A special feature of the system was the combined phonospectrographic view that could be used to analyse the features of the heart sounds and murmurs. The system was used to collect two independent heart sound databases in cooperation with Helsinki University Hospital and Lund University Hospital. Experienced paediatric cardiologists examined the children and analysed their heart sounds. The timing, duration, and frequency contents of heart sounds and murmurs were extracted from the sound signals. Statistical analysis was used to find the most significant features for screening between pathological and physiological cases. The system was capable of recording, displaying and replaying common heart murmurs in children. The characteristics of the heart murmurs in children were illustrated in phonospectrograms. The timing and quality of the cardiovascular sound events were measured from the graphical presentations. With the use of time interval and spectral analysis as well as a stepwise regression analysis model, all significant cardiac defects were correctly classified as pathological. In phonospectrographic analysis of heart murmurs in children, a sensitivity of 90% and specificity of 92% in screening for pathological heart murmurs were achieved. The digital phonocardiographic system for screening for heart murmurs in children can be implemented rather simply using an electronic stethoscope and a personal computer. The enhanced phonospectrographic presentation of the heart sounds and murmurs provides more information than traditional auscultation or phonocardiography alone. Simple features extracted from the phonospectrogram may significantly improve the diagnostic quality of primary healthcare in screening for heart murmurs in children and thus lead to more efficient use of personnel and technical resources in the whole healthcare system.
|Translated title of the contribution||Fonokardiografiajärjestelmän kehittäminen ja soveltaminen lasten sydänäänien tunnistamiseen|
|Publication status||Published - 2012|
|MoE publication type||G5 Doctoral dissertation (article)|
- digital signal processing
- heart sounds
- heart murmurs
- paediatric cardiology