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 . 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 .
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 . Several studies showed that smoking, alcohol intake, medications are factors, which reduce HRV.
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 . 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].
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...