Catheter Ablation -> Ventricular Arrhythmias -> Experimental methods D-PO06 - Poster Session VI (ID 26) Poster

D-PO06-087 - Impact Of Non-invasive Middle-dose External Particle Beam Radiation On The Electrophysiological And Pathological Changes In The Animal Heart (ID 1358)

Abstract

Background: Non-invasive radiotherapy using 25-Gy X-ray for hearts of patients with refractory ventricular tachycardia (VT) has shown a significant effect on VT suppression.
Objective: The aim of this study was to investigate the impact of radiotherapy using 25-GyE charged particle beams (carbon and proton beams) on hearts.
Methods: A total of 25 normal rabbits was used. External particle beam radiation for the hearts based on treatment planning CT was performed in 16 rabbits (25-GyE carbon beam: n=8, proton beam: n=8). The 9 rabbits were not irradiated (control). At the 3-6 month post-radiation follow up, all animals underwent open-heart electrophysiological studies (EPSs) and were euthanized for histological analyses.
Results: After the 3-6 month follow up, the left ventricle (LV) ejection fraction did not significantly differ between the control and radiation rabbits, however, the QRS wave voltage on the body surface ECG was significantly lower in the radiation rabbits (control: 0.5±0.3 mV, carbon beam 0.2±0.1 mV, proton beam 0.2±0.1 mV, p<0.001). Open-heart EPSs revealed that the LV voltage was significantly lower (control: 6.3±2.1 mV, carbon beam 5.0±1.6 mV, proton beam 4.6±1.6 mV, p=0.02) and LV anterior conduction time was significantly slower (control: 10±1 ms, carbon beam 15±5 ms, proton beam 14±1 ms, p<0.04) in the radiation rabbits. Histological analyses revealed apoptosis and fibrotic changes in the LV in the radiation group.
Conclusion: External middle-dose particle beam radiation had a significant electophysiological and histological impact on the beating heart, which could potentially develop a non-invasive ablation of the arrhythmogenic substrate in the heart.
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