Heart Rate and Blood Pressure Variability as Predictors for the Attacks in Patients with Neurocardiogenic Syncope (original) (raw)
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Investigation of the correlation between heart rate and heart rate variability
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.
Basic notions of heart rate variability and its clinical applicability
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.
HEART RATE VARIABILITY (HRV) -ANALYSIS AND CLINICAL SIGNIFICANCE
Heart rate variability (HRV) is a significant measure indicating how much variation exists in one's heartbeats within a specific timeframe. Two important models-the polyvagal theory and neurovisceral integration models and correlation among vagally assessed high-frequency heart-rate variability (HF-HRV) with neurovisceral integration describe the heart rate variability. The neurovisceral integration model explains the role of prefrontal cortex in regulating the limbic structures suppressing parasympathetic and activating sympathetic activities leading to HRV and modulation of HRV. Major methods for analyzing HRV are: a): Time-domain measurement; b): Geometric-measurement methods; c): Frequency-domain methods; and d): Non-linear measurement methods. Increase in vagal functional activity has indeed quite potential involvement. However, there is no clear clue indicating the extent of increase that might be beneficial. There are various cardiac diseases and non-cardiological diseases where decrease in HRV occurs. However, increase in HRV for well-being and normal health can be produced by several factors/ conditions for protective measures. Conclusively, the factors increasing the HRV may provide protection against cardiac disease, mortality and sudden death. However, it seems also important to keep in mind that there might not be always true to assume that too much high modification of HRV may bring cardiac protection.
Physiological Background Underlying Short-Term Heart Rate Variability
Annals of Noninvasive Electrocardiology, 1998
ABSTRACT A large number of papers has been published on heart rate variability (HRV) based on the assumption that the specific components of HRV provide specific information about cardiac parasympathetic or sympathetic efferent nerve activity. However, neural control of the cardiorespiratory system is very complex, and the physiological phenomenon underlying HRV in different conditions are far from being fully understood. This review summarizes, in the light of current literature, a series of studies focused on the mechanisms by which fluctuations in neural outflows are transferred into HRV. In the interpretation of HRV analyses, it should be taken into account that: (1) HRV seems to be strongly influenced by the parasympathetic nervous system at all the frequency components; (2) due to sympathovagal interactions, sympathetic outflow is able to reduce the variations generated by vagal modulation also in the high frequency band; and (3) the variations in heart rate reflect fluctuations in the neural activity rather than the mean level of sympathetic or parasympathetic neural activity. Thus, we should be cautious in interpreting a specific component of HRV as a specific marker of sympathetic or parasympathetic cardiac control. Furthermore, due to the complexity of the cardiorespiratory control system, the analysis of short-term HRV should be performed in well-controlled conditions, in which the behavior of the autonomic nervous system is well documented.
Heart Rate Variability: A Neuroscientific Perspective for Further Studies
Cardiac Electrophysiology Review, 1999
Heart rate variability (HRV) has proven to be a useful tool for studies of autonomic control and its central integration. Technical and analytical developments continue to advance the available methods for extract- ing accurate estimates of the components of heart rate variability, and two international committees of scien- tists have now recognized the potential utility of these measures for both research and clinical applications (1,2). Additional research is necessary, however, to more fully elucidate the mechanisms of HRV and to re~ne approaches to the interpretation of these meas- ures.
Journal of Cardiovascular and Thoracic Research
Introduction: Autonomic changes play an essential role in the genesis of neurally mediated syncope (NMS). The aim of this study was to compare the changes of the autonomic nervous system (ANS) by measuring spectral indices of beat-to-beat systolic blood pressure and heart rate variability (SBPV and HRV) in ranges of low frequency (LF), high frequency (HF), and the LF/HF ratio during head-up tilt test (HUTT) in patients with and without a syncope response. Methods: In this case-control study of 46 patients with a suspected history of unexplained syncope, data were recorded separately during the typical three phases of HUTT. Patients who developed syncope were designated as the case group and the rest as the control group. Results: Thirty one patients experienced syncope during HUTT. Resting HRV and SBPV indices were significantly lower in cases than controls. After tilting in the syncope group, both HF and LF powers of SBPV showed a significant and gradual decrease. LF/HF in HRV incr...
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.