Evaluation of the effects of mediastinal radiation therapy on autonomic nervous system

In this study, the effects of mediastinal radiation therapy on autonomic nervous system (ANS) was investigated by heart rate variability (HRV) analysis which is accepted as a noninvasive indicator of ANS. For this purpose, an experiment was designed and applied to 19 voluntary patients who came to Hacettepe University Medicine Faculty, Radiation Oncology Clinic. For the 1st and 15th fractions, electrocardiograms of the patients were recorded for 5 minutes just before irradiation (I. region), during irradiation (II. region) and for 5 minutes shortly after irradiation (III. region). Mean of RR intervals (ortRR) and standard deviation of RR intervals (ssRR), LF, HF powers of HRV and LF/HF ratio were calculated. Short-term effect of radiation on ANS was investigated by comparing the three regions selected for both the 1st and 15th fractions. For the 1st fraction, VLF, LF and LF/HF ratio increased during irradiation significantly. Calculated parameters for both the first and 15th fractions were compared to find out long-term effects of mediastinal radiation therapy on ANS activities. When the third region of the 1st and 15th fractions were compared, was seen ssRR, VLF, LF and HF decreased significantly. ortRR was significant for the first region. So, in conclusion; mediastinal radiotherapy can cause to decrease in ANS activities according to the prescribed radiation dose.