Análise da variância da frequência cardíaca no domínio do tempo dos intervalos R-R através de índices estatísticos e geométrico: um estudo comparativo entre indivíduos com batimentos cardíacos normais, portadores de insuficiência cardíaca congestiva e que sofreram infarto agudo miocárdio

Abstract

The autonomic nervous system (ANS) is responsible for controlling the cardiovascular system. This neural control is related to the heart rate (HR) where, through the afferent information of stimulus and inhibition interaction, responses of the sympathetic and parasympathetic pathways modify the HR, adapting it to the needs of each situation. The heart is a complex organ, does not have the regularity of a clock, and HR changes defined through heart rate variability (HRV) are normal and indicate the heart's ability to respond to multiple physiological and environmental stimuli such as breathing, physical stress, mental stress, hemodynamic and metabolic changes, sleep and etc., as well as compensate for disease-induced disorders. The SNA influences on the sinus node are related to HRV, which describes the consecutive oscillations of the intervals between consecutive heart beats (RR intervals). Since VFC is a noninvasive measure, time series can be used to identify characteristics and patterns in healthy individuals, athletes and patients with diverse pathologies. For HRV analysis in the time domain, each normal R-R interval (sinus beats) is measured over a period of time and based on statistical methods the translational indices of fluctuations in cardiac cycle duration (linear method) are calculated. In this study, we performed a comparative intra-group analysis and between groups of statistical indices (CV, mean RR intervals, SDNN, RMSSD and pNN50) and the triangular index of the RR intervals of individuals with normal heart beats with heart failure congestive heart failure and of individuals who suffered myocardial infarction. The database was obtained through the biomedical signal platform www.physionet.com and the MINITAB © and MATLAB © computational packages were used for calculations and index analyzes.