Paediatric heart sound signal analysis towards classification using multifractal spectra.

Healthy versus unhealthy heart sound computer-aided classification tools are very popular for supporting clinical decisions. In this paper a new method is proposed for the classification of heart sound recordings from a statistical standpoint without detection and localization of fundamental heart sounds (S1, S2). This study analyzes the possibility of detecting healthy heart sound signal from a large set of measurements, corresponding to different pathologies, such as aortic regurgitation, mitral regurgitation, aortic stenosis and ventricular septal defects. The proposed method employs singularity spectra analysis and long-term dependency of irregular structures. Healthy signals are firstly separated from the rest of the recordings. In the second step, the signals with a click syndrome, used here as a reference, are detected in the unhealthy group. Innocent murmurs have not been considered in this paper. Each auscultatory recording is classified into one of the following classes: healthy; click syndrome; and other heart dysfunctions. The results of the proposed method provided high recall and precision values for each of the three classes. Since the presence of additive noise may affect the classification, we also analyzed the possibility of classifying signals in such circumstances. The method was tested, verified and showed high accuracy.

Automatic heart sound detection in pediatric patients without electrocardiogram reference via pseudo-affine Wigner-Ville distribution and Haar wavelet lifting.

Having in mind the availability of electronic stethoscopes, phonocardiograms (PCGs) have become popular for cardiovascular functionality monitoring and signal processing applications. Detection of fundamental heart sounds (HSs), S1s and S2s, is considered to be a crucial step in PCG analysis. Electrocardiogram (ECG), noted as a reference signal, is often synchronously recorded in order to simplify the S1/S2 detection process. Nevertheless, electronic stethoscopes are frequently used without additional ECG equipment. We propose a new algorithm for automatic fundamental HSs detection via: joint time-frequency representation based on pseudo affine Wigner-Ville distribution (PAWVD), Haar wavelet lifting scheme (Haar-LS), normalized average Shannon energy (NASE) and autocorrelation. The performance of the proposed algorithm was calculated on both normal (50) and pathological (75) PCG recordings, eight seconds long each, contributed by 125 different pediatric patients. The algorithm showed relatively high recall (90.41%) and precision (96.39%) rates of S1/S2 detection procedure in a variety of PCG signals, without ECG as a reference. Furthermore, it indicated the ability to overcome splitting within the S1/S2 heart sounds.

Carotid artery intima-media thickness and brachial artery flow-mediated vasodilatation in patients with rheumatoid arthritis.

BACKGROUND: Cardiovascular (CV) morbidity and mortality are increased in patients with rheumatoid arthritis (RA). Our study aim was to determine the relationship between carotid artery intima-media wall thickness (IMT) and flow-mediated endothelium-dependent vasodilatation (FMD) in a patients with RA, in context with clinical and laboratory measurements. PATIENTS AND METHODS: Fifty-two patients with RA and 30 matched healthy controls without clinically evident CV disease were studied. Brachial and carotid ultrasonography was performed to determine FMD and IMT, respectively. We also assayed immunological, inflammatory and metabolic laboratory markers. RESULTS: IMT was significantly higher in RA patients (1.00 ± 0.16 mm) patients than in controls (0.89 ± 0.13 mm) (P = 0.001). FMD was significantly lower in RA (9.16 ± 7.03) as compared to controls (12.60 ± 5.49) (p = 0.005). RA patients had significant positive correlations between erythrocyte sedimentation rate (ESR) (r=0.395 p = 0.021) and IMT and negative correlation between visual analog scale (VAS) (r= -0.311, p= 0.025) and IMT. RA patients who used low doses of corticosteroids have, statistically, significantly better FMD, than those who do not use corticosteroids. Linear regression analysis revealed that IMT was related to tender joint count (p = 0.008), VAS (p < 0.001), ESR (p = 0.048) and total cholesterol/high density lipoprotein cholesterol ratio (p = 0.039). CONCLUSIONS: In patients with RA, FMD was impaired and IMT was increased, indicating early endothelial dysfunction and accelerated atherosclerosis. Early treatment of disease may reduce the risk of atherosclerosis in RA.