The effect of swallowing on heart rate variability analysis

Heart rate variability (HRV) analysis which was accepted as a noninvasive indicator of autonomous nervous system (ANS), has found a wide usage area in clinic and scientific researches. In this study firstly, the swallowing effect on standard HRV parameters, which was also first in literature, was investigated. For this purpose, regions with and without swallowing in HRV signals obtained from the experiment were compared with statistical methods. Some statistically meaningfull differences were observed in some HRV parameters for with swallowing region according to without swallowing region. Therefore, it was concluded that HRV analysis must be done with a method which determines swallowing for the purpose not to involve swallowing induced parts or a method must be improved for removing the swallowing effect on HRV. A method which was used previously to remove the effect of missing data on power spectrum density was applied to this problem for removing the swallowing effect on HRV analysis. In this method, the PSD was calculated with accepting swallowing induced regions as missing data. The efficiency of this method was tested with simulations and real HRV signals and the usefullness for removing the swallowing effect on HRV analysis was shown. Finally, as a result of the experimental and model based studies done for the investigation of the reason of swallowing induced changes seen on HRV, it was introduced that these changes are not occured only by respiration changes during swallowing. It was concluded that changes seen on HRV can be occured by the effect of pressure changes on baroreceptors or vagus nevre during swallowing.KEYWORDS: heart rate variability, swallowing, ECG, PSD, statistical test