CARDIAC SPECTRAL POWER REFLECTS PARASYMPATHETIC BUT NOT SYMPATHETIC NERVOUS-SYSTEM ACTIVITY IN A CLINICAL POPULATION

The purpose of this short communication is to report our clinical find ings regarding the use of the low frequency (LF, 0.02-0.15 Hz) and hig h frequency (HF, > 0.15 Hz) components of the spectral decomposition o f heart-rate as indices of sympathetic (SNS) and parasympathetic nervo us system (PNS) activity, respectively. Thirty-two females with histol ogically confirmed ovarian cancer, ranging in age from 46-72 years, pa rticipated in an autonomic assessment protocol consisting of a resting heart rate recording and several ANS function tests. The LF, HF and t otal power measures from the spectral decomposition were highly correl ated with one another. In addition, the spectral components were most highly correlated with measures of PNS activity, i.e. standard deviati on of heart rate at rest and the ratio of the six longest to the six s hortest R-R intervals during deep breathing (E:I ratio). It is conclud ed, as other researchers have stated, that the use of the HF component of the HR spectrum as a measure of PNS activity is warranted, but cau tion must be used when interpreting the LF component.