Efficiency evaluation of autonomic heart control by using the principal component analysis of ECG P-wave.

BACKGROUND: Cardiac output is controlled by the autonomic nervous system by changing the heart rate and/or the contractions of the heart muscle in response to the hemodynamic needs of the whole body. Malfunction of these mechanisms causes the postural orthostatic tachycardia syndrome and/or the chronic fatigue syndrome. Evaluation of functionality and efficiency of the control mechanisms could give valuable diagnostic information in the early stages of dysfunction of the heart control systems and help to monitor the healing process in rehabilitation period after interventions. OBJECTIVES: In this study we demonstrate how P-wave changes evoked by an orthostatic test could be quantitatively evaluated by using the method based on the principal component analysis. METHODS: ECG signals were recorded during an orthostatic test performed according to the typical protocol in three groups of volunteer subjects representing healthy young and older persons, part of which had transient periods of supraventricular arrhythmias. Quantitative evaluation of P-wave morphology changes was performed by means of principal component analysis-based method. RESULTS: Principal component-based estimates showed certain variety of P-wave shape during orthostatic test, what revealed a possibility to evaluate the properties of parasympathetic heart control. CONCLUSIONS: Quantitative evaluation of ECG P-wave changes evoked by an orthostatic test by using a newly developed method provides a quantitative estimate for functionality and efficiency of the heart rate control mechanisms. The method could be used in eHealth systems.

[Automatic analysis of cardiological signals for diagnosis of ischemic heart disease]. / Avtomaticheskii analiz kardiosignalov dlia diagnostiki ishemicheskoi bolezni serdtsa.

A new noninvasive method for early detection of ischemic heart disease based on singular value decomposition is introduced. The method automatically explores waveforms of an ECG by making projections of individual ECG leads onto axes formed by the first three components of the singular value decomposition performed for the whole group of ECGs, including cases with and without coronary artery lesions (460 ECGs). Detection of the presence of lesions is performed with 73% sensitivity and 83% specificity. Sensitivity and specificity become lower when specifying which coronary artery contains lesions: 69% and 77%, respectively, for the right coronary artery, 66% and 82%, respectively, for left anterior descending artery. 74% and 71%, respectively, for the left circumflex artery. The method is being developed so that it might be included into the programs of automatic ECG analysis, particularly for population studies.

[Testing experience with an automatic ECG analysis system in the cardiology clinic]. / Okyt ispytaniia sistemy avtomatizirovannogo analiza EKG v kardiologicheskoi klinike.

An original system of automated analysis of electrocardiosignals has been developed on the basis of computer EC-1022. The system consists of an appliance for the collection and recording of the electrocardiosignals (ECS), an arrangement for the input and output of ECS into the computer and the basic programs input, identification, measurement, rhythm, contour, formation, search, dispatcher. The system has been tested in a cardiological clinic. The computer and the medical conclusions coincided in 82% of cases.

[Accuracy and variability of medical interpretation of the electrocardiogram]. / O tochnosti i variabel'nosti vrachebnoi onterpretatsii EKG

The accuracy of medical interpretation of the ECG, the variability of electrocardiographic conclusions drawn by different physicians and by a specialist when re-analyzing the same ECG were considered. Three experienced physicians analyzed 700 ECG independently from one another. The electrocardiographic inferences were contrasted against the autopsy, roentgenographic and clinical findings. A paired comparison of electrocardiographic conclusions made by the physicians with respect to the principal groups of these conclusions was undertaken. The mean frequency of complete concurrence of the conclusions varied from 26 to 89 per cent, depending upon the type of the electrocardiographic conclusion. Subject to comparison were also conclusions drawn by a single physician with a two-fold analysis of the same ECG. In this case the frequency of divergent inferences amounted to 43 per cent.

Diagnosis of rheumatism by means of universal criteria, obtained by the cybernetic method.

With a view to establishing standardized criteria for the diagnosis of rheumatism suitable for widespread use in polyclinics and in large-scale epidemiological investigations, 3000 adults and children with rheumatism or one of seven similar diseases were subjected to multiple screening in eight centres in the USSR using a specially prepared standard card and standard methods. The information obtained was processed by cybernetic methods. Following determination of the sensitivity, specificity, and informational value of 486 signs of rheumatism, 68 of the most indicative signs were selected as criteria of rheumatism. These were included in the final table and weighted according to their indicational value both individually and in groups as syndromes. Using the table it is possible by simple calculation, without using a computer, to arrive at an objective evaluation of the reliability of the clinical diagnosis of rheumatism in patients with one of a group of eight similar diseases. The final diagnostic table was tested on 562 patients selected epidemiologically or from polyclinics or clinics and was shown to result in a high degree of diagnostic precision (higher than 95%).