engleski

Low to high frequency ratio of heart rate variability spectra fails to describe sympatho-vagal balance in cardiac patients

Heart rate variability (HRV) reflects an influence of autonomic nervous system on heart work. In healthy subjects, ratio between low and high frequency components (LF/HF ratio) of HRV spectra represents a measure of sympatho-vagal balance. The ratio was defined by authorities as a useful clinical tool, but it seems that it fails to summarise sympatho-vagal balance in a clinical setting. Value of the method was re-evaluated in several categories of cardiac patients. HRV was analysed from 24-hour Holter ECGs in 132 healthy subjects and 2159 cardiac patients, divided by gender, median of age, diagnosis of myocardial infarction or coronary artery surgery, left ventricular systolic function and by several categories of overall HRV. In healthy subjects, LF/HF ratio correlated with overall HRV negatively, as expected. The paradoxical finding was obtained in cardiac patients ; the lower the overall HRV and the time-domain indices of vagal modulation activity, the lower the LF/HF ratio. If used as a measure of sympatho-vagal balance, long-term recordings of LF/HF ratio contradict to clinical finding and time-domain HRV indices in cardiac patients. The ratio cannot therefore be used as a reliable marker of autonomic activity in a clinical setting.

heart rate; nervous system; autonomic; heart disease

nije evidentirano