Summary
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 ortho-static 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 para-sympathetic
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.
Keywords
Principal component analysis - autonomic heart control - ECG P-wave
