Heart rate variability: Highlights from hidden signals

MGM Journal of Medical Sciences, 2016

Heart rate variability (HRV) came into existence by observations of Hon and Lee in 1965 and since then has been a subject of prime importance in medical research. It is derived from changes in RR intervals in a continuous recording of electrocardiogram. Different types of measurements are carried out on these RR intervals in time and frequency domain. Among others, variance, total power, low-frequency (LF) power, high-frequency (HF) power, and LF/HF ratio are frequently used HRV parameters for objective assessment of autonomic function and assessment of several clinical conditions. Poincare plot gives a quick visual impression of HRV. This article describes measurement of all these parameters and their clinical applications.

Scandinavian Journal of Work, Environment & Health, 1995

Folia Medica, 2015

The autonomic nervous system controls the smooth muscles of the internal organs, the cardiovascular system and the secretory function of the glands and plays a major role in the processes of adaptation. Heart rate variability is a non-invasive and easily applicable method for the assessment of its activity. The following review describes the origin, parameters and characteristics of this method and its potential for evaluation of the changes of the autonomic nervous system activity in different physiological and pathological conditions such as exogenous hypoxia, physical exercise and sleep. The application of heart rate variability in daily clinical practice would be beneficial for the diagnostics, the outcome prognosis and the assessment of the effect of treatment in various diseases.

2009

Among the techniques used in its evaluation, the heart rate variability (HRV) has arising as a simple and non-invasive measure of the autonomic impulses, representing one of the most promising quantitative markers of the autonomic balance. The HRV describes the oscillations in the interval between consecutive heart beats (RR interval), as well as the oscillations between consecutive instantaneous heart rates. It is a measure that can be used to assess the ANS modulation under physiological conditions, such as wakefulness and sleep conditions, different body positions, physical training and also pathological conditions. Changes in the HRV patterns provide a sensible and advanced indicator of health involvements. Higher HRV is a signal of good adaptation and characterizes a health person with efficient autonomic mechanisms, while lower HRV is frequently an indicator of abnormal and insufficient adaptation of the ANS, provoking poor patient's physiological function. Because of its importance as a marker that reflects the autonomic nervous system activity on the sinus node and as a clinical instrument to assess and identify health involvements, this study reviews conceptual aspects of the HRV, measurement devices, filtering methods, indexes used in the HRV analyses, limitations in the use and clinical applications of the HRV.

Clinical Cardiology, 1997

Heart rate variability (HRV) has recently become a popular noninvasive research tool in cardiology. Clinical assessment of HRV is frequently based on standard long-term ambulatory electrocardiograms, whereas physiologic studies employ spectral analysis of short-term recordings under controlled conditions. From a general point of view, HRV can be used in clinical practice to estimate (1) the integrity of cardiac autonomic innervation, (2) the physiologic status of cardiac autonomic activity, and (3) the vulnerability to various cardiac arrhythmias resulting from autonomic imbalance. Clinical relevance of HRV has been clearly demonstrated in only two clinical conditions: (1) impaired HRV can be used alone or in a combination with other factors to predict risk of arrhythmic events after acute myocardial infarction, and (2) decrease in HRV is a useful clinical marker for evolving diabetic neuropathy. Substantial advances of our knowledge are required to establish and promote clinical applications in other areas of clinical medicine. To accomplish this task, proper hypotheses should be studied and appropriate techniques selected.

Cardiovascular Research, 2001

Progress in Cardiovascular Diseases, 2012

Heart rate variability (HRV) non-invasively assesses the activity of the autonomic nervous system. During the past 30 years, an increasing number of studies have related the imbalance of the autonomic nervous system (as assessed by HRV) to several pathophysiogical conditions, particularly in the setting of cardiovascular disease. Sudden death, coronary artery disease, heart failure, or merely cardiovascular risk factors (smoking, diabetes, hyperlipidemia, and hypertension) are the best-known clinical circumstances that can affect and/or be affected by the autonomic nervous system. Analyses of HRV variables have been proposed as a component of the clinical evaluation for patient risk stratification due to its independent prognostic information. Yet the potential for HRV to be used widely in clinical practice remains to be established.

Journal of The American College of Cardiology, 1999

The objectives of this review are to discuss the diversity of mechanisms that may explain the association between heart rate (HR) variability and mortality, to appraise the clinical applicability of traditional and new measures of HR variability and to propose future directions in this field of research.

Computers in Cardiology 1995, 1995

Pathologic conditions are flequently associated with ntarked changes in heart rate (HR), which itself influences ifs variability (HR v). Accordingly, some researchers consider the HR and the HR V to he equivalent measures. Question: Does the HRV afford dvferent information than the HR itself7 Method: The HRV were investigated in ten patients during a normal autonomic tone and a pharmacological autonomic b lockade, respectively. The results were analysed by calculation of the product-nroment correlation coeflcient and by means of linear regression of he HRV and the HR. Results: Signrficant correldion were found between the IIR and all of the HRV bands. The regression coeflcients of the HR and HRI' increased mnrkedy qper a .ympathetic blockade. The extent of the rqression decreased to nearly zero dtrring a total ve,qetnti\*e blockade. C'onclusions: ( I ) ll?ere is a signijicant negative correlation between the HR and the HRV.