Investigation of the Chronic Effects of Radiotherapy on the Electrical Activity of the Heart Using an Experimental Rat Model

Abstract

Radiotherapy is widely used in the treatment of lymphoma, lung cancer, mediastinal, and breast cancers. It is known that radiation adversely affects healthy cells as well as cancer cells. Today, data obtained from cancer patients undergoing radiotherapy also indicate an increase in cardiovascular-related mortality rates. In this study, it was aimed to investigate the chronic effect of radiotherapy on the electrical activity of the heart using an experimental rat model. Twelve female Wistar albino rats weighing between 200-250 g on average were used in the study. The rats were divided into two groups as control and radiotherapy with 6 animals in each group. A total radiation dose of 20 Gy was administered to the radiotherapy group. Three months after the irradiation, electrocardiography (ECG) recordings were taken from the rats under anesthesia. The amplitudes and durations of the P wave, QRS complex, and T waves in the electrocardiogram were evaluated. Additionally, P-R and Q-T intervals and heart rate were measured. Statistical analysis showed that the amplitude of the QRS complex was significantly reduced in the radiotherapy group compared to the control, while the amplitude of the T wave increased. The P-R interval and T wave duration were prolonged and the heart rate decreased. As a result, it was observed that a single dose of 20 Gy therapeutic radiation applied to the intrathoracic region impaired the conduction of electrical impulses in the hearts of healthy rats. However, more comprehensive research is needed on this subject.