Validity of the Polar V800 heart rate monitor to measure RR intervals at rest

Purpose To assess the validity of RR intervals and short-term heart rate variability (HRV) data obtained from the Polar V800 heart rate monitor, in comparison to an electrocardiograph (ECG). Method Twenty participants completed an active orthostatic test using the V800 and ECG. An improved method for the identification and correction of RR intervals was employed prior to HRV analysis. Agreement of the data was assessed using intra-class correlation coefficients (ICC), Bland–Altman limits of agreement (LoA), and effect size (ES). Results A small number of errors were detected between ECG and Polar RR signal, with a combined error rate of 0.086 %. The RR intervals from ECG to V800 were significantly different, but with small ES for both supine corrected and standing corrected data (ES 0.999 for both supine and standing corrected intervals. When analysed with the same HRV software no significant differences were observed in any HRV parameters, for either supine or standing; the data displayed small bias and tight LoA, strong ICC (>0.99) and small ES (≤0.029). Conclusions The V800 improves over previous Polar models, with narrower LoA, stronger ICC and smaller ES for both the RR intervals and HRV parameters. The findings support the validity of the Polar V800 and its ability to produce RR interval recordings consistent with an ECG. In addition, HRV parameters derived from these recordings are also highly comparable

Effects of exercise on cardiac autonomic modulation in children: literature update

AbstractIntroduction It is known that physical exercise is beneficial and precipitates adjustments to the autonomic nervous system. However, the effect of exercise on cardiac autonomic modulation in children, despite its importance, is poorly investigated.Objective To bring together current information about the effects of exercise on heart rate variability in healthy and obese children.Methods The literature update was performed through a search for articles in the following databases; PubMed, PEDro, SciELO and Lilacs, using the descriptors “exercise” and “child” in conjunction with the descriptors “autonomic nervous system”, “sympathetic nervous system”, “parasympathetic nervous system” and also with no descriptor, but the key word of this study, “heart rate variability”, from January 2005 to December 2012.Results After removal of items that did not fit the subject of the study, a total of 9 articles were selected, 5 with healthy and 4 with obese children.Conclusion The findings suggest that exercise can act in the normalization of existing alterations in the autonomic nervous system of obese children, as well as serve as a preventative factor in healthy children, enabling healthy development of the autonomic nervous system until the child reaches adulthood

MODULAÇÃO AUTONÔMICA DA FREQUÊNCIA CARDÍACA E CAPACIDADE FUNCIONAL AERÓBICA EM HEMIPARÉTICOS

RESUMO Introdução: Tem sido observado que indivíduos acometidos por acidente vascular encefálico (AVE) apresentam, além dos danos físicos, diminuição da capacidade aeróbica e alteração da modulação autonômica da frequência cardíaca, sendo estes importantes fatores para o aparecimento de doenças cardíacas e arritmias. Objetivo: Investigar os efeitos crônicos do AVE sobre a capacidade aeróbica (VO2pico) e os índices de variabilidade da frequência cardíaca (VFC), e se existe correlação entre essas duas variáveis. Métodos: Foram avaliados 11 indivíduos do sexo masculino, com idade entre 55 e 65 anos, acometidos por lesão cerebrovascular há pelo menos seis meses, e todos com hemiparesia. Foram realizadas as seguintes avaliações: teste de capacidade aeróbica máxima; registro dos intervalos R-R e cálculo dos índices da VFC (RMSSD, pNN50, AF, BF e a razão BF/AF). Para comparação entre VO2pico previsto e obtido utilizou-se o teste t de Student não pareado. Para testar a hipótese de correlação entre os índices de VFC e o VO2pico utilizou-se o teste de correlação de Pearson. Resultados: VO2pico (mL.kg-1.min-1) previsto e obtido, respectivamente = 32,15 ± 1,87 e 16,12 ± 5,51; índices da VFC: RMSSD (ms) = 28,69 ± 26,78; pNN50 (%) = 8,76 ± 12,62; AF (u.n.) = 51,96 ± 22,4; BF (u.n.) = 48,04 ± 22,49. O VO2pico correlacionou-se negativamente com os índices RMSSD, pNN50 e AF e positivamente com o índice BF (p < 0,05). Conclusão: Na fase crônica do AVE, variabilidade da frequência cardíaca encontra-se normal e os indivíduos com menor capacidade aeróbica apresentam maior modulação parassimpática e menor simpática, provavelmente em consequência da maior exigência física nas atividades de vida diária

Measurements of Cardiovascular Signal Complexity for Advanced Clinical Applications

Over the last decades, there has been an increasing interest in the analysis of Heart Rate Variability (HRV). Many parameters were proposed to properly describe the complex systems controlling the heart rate, while involving neural mechanisms (through the Autonomic Nervous System), as well as mechanical and humoral factors. After a first effort to rationalize all these parameters in 1996 (the \u201cHRV Task Force\u201d), a second paper in 2015, reported the consensus reached on the critical review of the new methods. The latter tried in particular to address the clinical impact of the nonlinear techniques, considering only studies with sufficiently sized populations. In this chapter, we relax the constrain on the number of patients and try to identify all those techniques which resonated in the scientific community and were applied and studied more than others. To guide our analysis, we considered a different set of objective criteria, based mainly on the number of citations received. Our analysis show that all the parameters which were clinically relevant in the 2015 paper, proved also to have a significant impact in the methodological literature. However, other parameters received much more methodological interest than the clinical results they were capable to provide. Among these: several entropy measures and the metrics derived from nonlinear dynamical systems, multifractality and wavelets. The reasons of this lack of clinical results might be many, but the complexity of these techniques and the disconnection, which frequently happens between bioscientists/biomedical engineers and medical centers, are likely possible explanations