Stefan Sammito

Reference values for time- and frequency-domain heart rate variability measures

BACKGROUND The analysis of heart rate variability (HRV) has become an established procedure in recent decades. Because there are no appropriate reference values available, HRV findings can still only be compared within a group or in individuals in longitudinal studies. OBJECTIVE The objectives of the present study were to examine a group of healthy subjects of different ages and sexes and to identify reference values for common HRV parameters. METHODS Long-term 24-hour electrocardiograms of 695 voluntary subjects were recorded by using a 2-channel Holter system over a period of 24 hours during daily activities. RESULTS Reference values for men and women in 10-year age groups were calculated for standard deviation of NN intervals, root mean square of successive differences of NN intervals, standard deviation of the average of all consecutive 5-minute NN intervals, percentage of consecutive NN intervals that deviate from one another by more than 50 ms, low-frequency power normalized unit, high-frequency power normalized unit, low frequency/high frequency ratio, SD1, and SD2. The 5th and 95th percentiles were given for each sex and for the age groups 20-30, 30-40, 40-50, and 50-60 years. We observed a consistent decrease in HRV measures with increasing age as well as a sex dependency of HRV findings. CONCLUSION We studied a large group of healthy subjects and identified reference values for commonly used HRV measures for 24-hour ECG measurements. The reference values differed considerably from the values published in 1996 in the Guidelines of the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. In the future, steps should be taken to expand the database and define reference values for the age groups under 20 and over 60 years. It would be desirable to obtain reference values for short-term recordings (eg, 5-minute recordings) as well.

The circadian rhythm of heart rate variability

Abstract Purpose: In recent years, the measurement of heart rate variability (HRV) has gained ground even outside research settings in everyday clinical and outpatient practice and in health promotion. Methods: Using the search terms “heart rate variability”, “hrv” and “circadian”, a systematic review was carried out in the PubMed database to find original work that analysed the course of HRV parameters over a 24-h period. Results: A total of 26 original studies were found. Almost all the studies detected a circadian rhythm for the HRV parameters analysed. HRV increased during the night in particular and a nighttime peak during the second half of the night was identified. Conclusions: HRV follows a circadian rhythm. But until today, there isn′t any possibility to make quantitative statements about changes over the course of the day for planning short-term measurements. More qualitative studies must be carried in order to close this knowledge gaps.

Möglichkeiten und Einschränkungen der Herzfrequenzmessung und der Analyse der Herzfrequenzvariabilität mittels mobiler Messgeräte

BACKGROUND Heart rate (HR) and heart rate variability (HRV) have been established in the last few years as a non-invasive method for recording the demands on the cardiovascular system. The development enables us today to measure the interbeat intervals with different technologies for calculating HR and HRV. MATERIALS AND METHODS This review is based on a systematic literature search in PubMed for validity of different measurement techniques and their pros and cons for the measurement of HR and the analysis of HRV. RESULTS Measurement equipment for recording of interbeat intervals should have a high storage capacity and a sampling rate of 1000 Hz ideally. The quality criteria of freedom of feedback (small, little disruptive), robustness and a non-invasive measurement (e. g. freeze-electrodes or sensors) have to be fulfilled. In addition to the Holter ECG, several portable heart rate watch and chest belt systems provide adequate validity and good applicability. DISCUSSION The Holter ECG is still the gold standard for the measurement of NN intervals and for the analysis of HRV. Modern heart rate watches show a good correlation with the conformance of freedom from discomfort, robustness and non-invasive measurement and are a good alternative due to the lower disturbance of test persons.

Analyse der Herzfrequenzvariabilität

The analysis of heart rate variability (HRV) has recently become established as a non-invasive measurement for estimation of demands on the cardiovascular system. The HRV reflects the interaction of the sympathetic and parasympathetic nervous systems and allows the influence of the autonomic nervous system on the regulation of the cardiovascular system to be mathematically described. This review explicates the analysis method of HRV for time, frequency and non-linear methods as well as the range of parameters and the demand on acquisition time. The necessity and possibilities of artefact correction and advice for the selection of a reasonable acquisition period are discussed and standard values for selected HRV parameters are presented.ZusammenfassungDie Analyse der Herzfrequenzvariabilität (HRV) hat sich in den letzten Jahren zu einer etablierten nicht-invasiven Erfassung des Beanspruchungsgrades des Herz-Kreislauf-Systems entwickelt. Hierbei spiegelt die HRV das Zusammenspiel zwischen Sympathikus und Parasympathikus, die die Aktivität des Herzens steuern, wider und ermöglicht es dem Untersucher, den Einfluss des autonomen Nervensystems auf die Regulierung des Herz-Kreislauf-Systems mathematisch zu beschreiben. Diese Übersichtsarbeit befasst sich mit den Analyseverfahren der HRV in den zeitbezogenen, frequenzbezogenen und nichtlinearen Methoden. Hinweise zur Auswahl des sinnvollen Erfassungszeitraums werden diskutiert sowie die Richtwerte für ausgewählte HRV-Parameter präsentiert.AbstractThe analysis of heart rate variability (HRV) has recently become established as a non-invasive measurement for estimation of demands on the cardiovascular system. The HRV reflects the interaction of the sympathetic and parasympathetic nervous systems and allows the influence of the autonomic nervous system on the regulation of the cardiovascular system to be mathematically described. This review explicates the analysis method of HRV for time, frequency and non-linear methods as well as the range of parameters and the demand on acquisition time. The necessity and possibilities of artefact correction and advice for the selection of a reasonable acquisition period are discussed and standard values for selected HRV parameters are presented.

Prevalence of Cardiac Arrhythmia Under Stress Conditions in Occupational Health Assessments of Young Military Servicemen and Servicewomen

OBJECTIVES In health assessments of young temporary-career volunteers who are up for re-enlistment, cardiac stress tests are mandatory to detect cardiac diseases and to confirm physical fitness. So far, there is no information available regarding the extent to which this time-consuming examination contributes to the diagnosis of pathological cardiac arrhythmia in this young, preselected patient collective. METHODS In a retrospective data analysis, health assessments of 1919 temporary-career volunteers conducted between 2007 and 2012 were examined with regard to pathological findings provided by resting electrocardiograms (ECGs) and exercise ECGs. RESULTS Only five subjects showed signs of heart disease during the resting ECG; none of the exercise ECGs revealed any abnormalities, even after further cardiological examinations. CONCLUSIONS In health assessments of young temporary-career volunteers, the exercise ECG as a mandatory examination should be replaced by the resting ECG. In addition to avoiding unnecessary examinations and associated risks, quite a large number of working years could be saved both for medical personnel and the persons examined.

Möglichkeiten und Einschränkungen der Herzfrequenzmessung und der Analyse der Herzfrequenzvariabilität mittels mobiler MessgeräteOptions and limitations of heart rate measurement and analysis of heart rate variability by mobile devices

BACKGROUND Heart rate (HR) and heart rate variability (HRV) have been established in the last few years as a non-invasive method for recording the demands on the cardiovascular system. The development enables us today to measure the interbeat intervals with different technologies for calculating HR and HRV. MATERIALS AND METHODS This review is based on a systematic literature search in PubMed for validity of different measurement techniques and their pros and cons for the measurement of HR and the analysis of HRV. RESULTS Measurement equipment for recording of interbeat intervals should have a high storage capacity and a sampling rate of 1000 Hz ideally. The quality criteria of freedom of feedback (small, little disruptive), robustness and a non-invasive measurement (e. g. freeze-electrodes or sensors) have to be fulfilled. In addition to the Holter ECG, several portable heart rate watch and chest belt systems provide adequate validity and good applicability. DISCUSSION The Holter ECG is still the gold standard for the measurement of NN intervals and for the analysis of HRV. Modern heart rate watches show a good correlation with the conformance of freedom from discomfort, robustness and non-invasive measurement and are a good alternative due to the lower disturbance of test persons.

Möglichkeiten und Einschränkungen der Herzfrequenzmessung und der Analyse der Herzfrequenzvariabilität mittels mobiler Messgeräte@@@Options and limitations of heart rate measurement and analysis of heart rate variability by mobile devices: Eine systematische Literaturübersicht@@@A systematic review

BACKGROUND Heart rate (HR) and heart rate variability (HRV) have been established in the last few years as a non-invasive method for recording the demands on the cardiovascular system. The development enables us today to measure the interbeat intervals with different technologies for calculating HR and HRV. MATERIALS AND METHODS This review is based on a systematic literature search in PubMed for validity of different measurement techniques and their pros and cons for the measurement of HR and the analysis of HRV. RESULTS Measurement equipment for recording of interbeat intervals should have a high storage capacity and a sampling rate of 1000 Hz ideally. The quality criteria of freedom of feedback (small, little disruptive), robustness and a non-invasive measurement (e. g. freeze-electrodes or sensors) have to be fulfilled. In addition to the Holter ECG, several portable heart rate watch and chest belt systems provide adequate validity and good applicability. DISCUSSION The Holter ECG is still the gold standard for the measurement of NN intervals and for the analysis of HRV. Modern heart rate watches show a good correlation with the conformance of freedom from discomfort, robustness and non-invasive measurement and are a good alternative due to the lower disturbance of test persons.

Relevant Errors Relating to the Measuring Method

Warth et al. (1) have contributed an important addition relating to the higher evidence of music therapy in palliative care and have shown the benefits of music therapy compared with a control arm in a randomized controlled trial using the intention-to-treat principle for its data analysis in 84 patients. However, in measuring and explaining the endpoint “Triggering of a physiological relaxation response” by means of heart rate variability (HRV) they made two crucial methodological errors. On the one hand, they used photoplethysmography to measure the intervals between successive heartbeats. In contrast to an ECG-based measurement of the RR intervals, the measurement of the pulse rate is affected by further factors—vascular stiffness, among others. A systematic review (2) found that pulse oximeters are suitable for measuring RR intervals to a very limited degree only. Formally, the correct term to be used should not be HRV but, in this case, pulse rate variability (PRV). Especially the high frequency band is subject to overestimates in PRV compared with HRV, as has also been shown elsewhere (3). For this reason, national guidelines on HRV do not recommend this measuring method (4). On the other hand, only the HF band was considered. This may wrongly be interpreted as raised if the analysis does not include the total power (TP) as the reference value. An increase in the HF in a setting of a simultaneous stronger increase in the other frequency bands (for example, LF) is imaginable, which would mean that the relative proportion of the purely parasympathetic HF band even decreases. Preferably the HF that uses the total power as the reference value could be used (4) or, additionally, the changes of other frequency bands, including the parameter LF/HF ratio, might also be considered.