Horizon 2030 Innovative Applications Of Heart Rate Variability

Over the last decades, assessment of heart rate variability (HRV) has increased in various fields of research. HRV describes changes in heartbeat intervals, which are caused by autonomic neural regulation, i.e. by the interplay of the sympathetic and the parasympathetic nervous systems. The most frequent application of HRV is connected to cardiological issues, most importantly to the monitoring of post-myocardial infarction patients and the prediction of sudden cardiac death. Analysis of HRV is also frequently applied in relation to diabetes, renal failure, neurological and psychiatric conditions, sleep disorders, psychological phenomena such as stress, as well as drug and addiction research including alcohol and smoking. The widespread application of HRV measurements is based on the fact that they are noninvasive, easy to perform, and in general reproducible – if carried out under standardized conditions. However, the amount of parameters to be analysed is still rising. Well-established time domain and frequency domain parameters are discussed controversially when it comes to their physiological interpretation and their psychometric properties like reliability and validity, and the sensitivity to cardiovascular properties of the variety of parameters seems to be a topic for further research. Recently introduced parameters like pNNxx and new dynamic methods such as approximate entropy and detrended fluctuation analysis offer new potentials and warrant standardization. However, HRV is significantly associated with average heart rate (HR) and one can conclude that HRV actually provides information on two quantities, i.e. on HR and its variability. It is hard to determine which of these two plays a principal role in the clinical value of HRV. The association between HRV and HR is not only a physiological phenomenon but also a mathematical one which is due to non-linear (mathematical) relationship between RR interval and HR. If one normalizes HRV to its average RR interval, one may get ‘pure’ variability free from the mathematical bias. Recently, a new modification method of the association between HRV and HR has been developed which enables us to completely remove the HRV dependence on HR (even the physiological one), or conversely enhance this dependence. Such an approach allows us to explore the HR contribution to the clinical significance of HRV, i.e. whether HR or its variability plays a main role in the HRV clinical value. This Research Topic covers recent advances in the application of HRV, methodological issues, basic underlying mechanisms as well as all aspects of the interaction between HRV and HR.

The vagus nerve is responsible for the regulation of all our internal organ functions. When it is damaged, the wide-ranging impact on our nervous system can manifest in a multitude of ways, including anxiety, hormonal imbalances, gastrointestinal distress, and vertigo. Based on current research into the vagus nerve and vagus nerve stimulation, this practical guide addresses a crucial missing link in healthcare and functional medicine by providing an innovative protocol on the management of anxiety and vagus nerve dysfunction through nutrition, exercise, and lifestyle. With a holistic, whole-person approach, this protocol bridges the divide between the physical and the psychological, providing a holistic approach that can be applied widely across various disciplines within healthcare, bodywork, and mental health. It provides detailed theory and is supplemented with an abundance of practical guidance including various recipes whilst also helping practitioners understand how clients may transition to a more sustainable, long-term protocol.

Over the last decades, assessment of heart rate variability (HRV) has increased in various fields of research. HRV describes changes in heartbeat intervals, which are caused by autonomic neural regulation, i.e. by the interplay of the sympathetic and the parasympathetic nervous systems. The most frequent application of HRV is connected to cardiological issues, most importantly to the monitoring of post-myocardial infarction patients and the prediction of sudden cardiac death. Analysis of HRV is also frequently applied in relation to diabetes, renal failure, neurological and psychiatric conditions, sleep disorders, psychological phenomena such as stress, as well as drug and addiction research including alcohol and smoking. The widespread application of HRV measurements is based on the fact that they are noninvasive, easy to perform, and in general reproducible - if carried out under standardized conditions. However, the amount of parameters to be analysed is still rising. Well-established time domain and frequency domain parameters are discussed controversially when it comes to their physiological interpretation and their psychometric properties like reliability and validity, and the sensitivity to cardiovascular properties of the variety of parameters seems to be a topic for further research. Recently introduced parameters like pNNxx and new dynamic methods such as approximate entropy and detrended fluctuation analysis offer new potentials and warrant standardization. However, HRV is significantly associated with average heart rate (HR) and one can conclude that HRV actually provides information on two quantities, i.e. on HR and its variability. It is hard to determine which of these two plays a principal role in the clinical value of HRV. The association between HRV and HR is not only a physiological phenomenon but also a mathematical one which is due to non-linear (mathematical) relationship between RR interval and HR. If one normalizes HRV to its average RR interval, one may get 'pure' variability free from the mathematical bias. Recently, a new modification method of the association between HRV and HR has been developed which enables us to completely remove the HRV dependence on HR (even the physiological one), or conversely enhance this dependence. Such an approach allows us to explore the HR contribution to the clinical significance of HRV, i.e. whether HR or its variability plays a main role in the HRV clinical value. This Research Topic covers recent advances in the application of HRV, methodological issues, basic underlying mechanisms as well as all aspects of the interaction between HRV and HR.

Heart rate variability (HRV) has become a popular method to study autonomic modulation of the cardiovascular system. Cardiovascular health depends on the proper functioning of several physiological systems, including the autonomic nervous system, which exerts its function via a complex interaction between its two branches: sympathetic and parasympathetic. Additionally, heart rate variability has been widely applied in basic and clinical research studies for describing the extent of sinus arrhythmia, and for assessing the function of cardiac autonomic regulation quantitatively. In other words, it is a mirror of the balance of sympathetic and vagal activity. This book discusses the prognostic significance, risk factors and clinical applications of heart rate variability.

Based upon the hypothesis that prognosis in childhood heart failure depends on autonomic dysfunction, the author introduced a new heart failure model and a medical therapy with beta-blockers in 1996. The author used the analysis of heart rate variability (HRV) in 24 hours Holter ECG's for the understanding of the pathophysiology of childhood heart failure and for objective control of medical therapy. The success of this clinical model was the inspiration of a new approach to mental disease in childhood. In the last decades, an increase of new paediatric problems requiring medical care like eating disorders, behavioural and attention problems has been observed. All these diseases are related to autonomic dysfunction and have a high impact on cardiovascular prognosis. Based upon the hypothesis that behavioural problems are accompanied by changes in the autonomic nervous system, the author performed analysis of HRV in 24 hours Holter ECG's in these patient groups: healthy children with respect to school affiliation; a historical control group from literature published in 1997; attention deficit disorder with and without hyperactivity; anorexia nervosa and obesity. This data was compared to children with an increased cardiovascular risk due to congenital heart disease. In order to analyse the effect of autonomic function on human growth, we measured HRV in children with growth failure. A new HRV Score was established for the comparison of autonomic function in different age groups. The author could demonstrate a decrease of vagal activity in healthy children in children of today and speculate that insufficient vagal maturation may be a reason for an increasing prevalence of mental and cardiovascular disease. Looking for the reason of this vagal shift, caloric over nutrition, omega-3-fatty acid deficiency, high intensity of information and communication technology usage and some environmental toxins reduce HRV in childhood.

This book introduces readers to the basic concepts of Heart Rate Variability (HRV) and its most important analysis algorithms using a hands-on approach based on the open-source RHRV software. HRV refers to the variation over time of the intervals between consecutive heartbeats. Despite its apparent simplicity, HRV is one of the most important markers of the autonomic nervous system activity and it has been recognized as a useful predictor of several pathologies. The book discusses all the basic HRV topics, including the physiological contributions to HRV, clinical applications, HRV data acquisition, HRV data manipulation and HRV analysis using time-domain, frequency-domain, time-frequency, nonlinear and fractal techniques. Detailed examples based on real data sets are provided throughout the book to illustrate the algorithms and discuss the physiological implications of the results. Offering a comprehensive guide to analyzing beat information with RHRV, the book is intended for masters and Ph.D. students in various disciplines such as biomedical engineering, human and veterinary medicine, biology, and pharmacy, as well as researchers conducting heart rate variability analyses on both human and animal data.