Heart rate variability good cardiovascular risk indicator



Heart rate measured over period of time is the heart rate variability (HRV), which is expressed in beats per minute (bpm). HRV is the change of consecutive heart beats over the time. Heart rate and its rhythm controlled by sinoatrial (SA) node, which is controlled by autonomic nervous system [9]. HRV could be valuable to evaluate sympathetic and parasympathetic system function. Stress, physical exercises, causes of heart diseases stimulates sympathetic nervous system by increasing heart rate. Allergic reactions, traumas result to parasympathetic nervous system, which is a consequence to reduction of heart rate [9].
Age and gender impacts HRV. It was proved that a higher HRV in physically active young people. At the ages between 20 to 70 years and it decreases with age and greater variation remain in a woman than in man [9]. Several studies showed that smoking, alcohol intake, medications are factors, which reduce HRV.

Heart rate variability frequency distribution

Wolf et al. in 1977 was the first who showed that reduced HRV after myocardial infarction has greater risk of death. And after 1980, HRV became a strong and independent predictor in patients after post-myocardial infarction [13]. Many present studies showed that reduced HRV is the indicator of increased mortality risk. Nowadays, HRV becoming relevant cardiovascular risk indicator, and there exist several methods for the risk evaluation. Most popular methods are time domain, frequency domain and geometrical analysis [12, 13].
Heart rate variability (HRV)
Heart rate variability (HRV)
Time domain analysis is the most valuable method for the prediction of mortality risk in patients after postmyocardial infarction, or patients with congestive heart failure. Standard deviation of all NN intervals (SDNN) in long-term 24h or short-term 5-minutes measurements is the indicator of increased mortality risk after post18 myocardial infarction if SDNN...



2015 Heart Risk Warner
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