Presentation A Potential Modality of Heavy Ion Beams for Intractable Ventricular Arrhythmia

古澤, 佳也  ,  網野, 真理  ,  吉岡, 公一郎

Most cause of death of ischemic heart disease or cardiomyopathy is a lethal ventricular arrhythmia. In recent years, catheter ablation is established for treatment of tachyarrhythmia. Drug therapy is focused on arrhythmia therapy under consideration of the patient characteristics. However, there is no curative treatment in lethal ventricular arrhythmias. Many ventricular tachycardia or ventricular fibrillation (VT/VF) associated with myocardial infarction (MI) is caused by disfunction of myocardium or nerves just below the epicardium in many cases. HIMAC1) (Heavy Ion Medical Accelerator in Chiba) have constructed for cancer treatment in NIRS (National Institute of Radiological Sciences) and shows an excellent achievement. We started a research to apply carbon ion beams for ablation treatment of arrhythmia using HIMAC 20 years ago. In the middle of the research, we have found2) that exposure of carbon beam can improve conductivity of electronic signals through induction of connexin43 (CX43) and reduce VT/VT. We expose heavy ion beams (290 MeV/u 5mm SOBP beam in 20 x20 mm2 area with maximum 30 mm depth, 5-15 Gy single exposure) to healthy and microsphere injected MI New Zealand white rabbits (n=2x24, 3.5-4.0 kg BW) heart partially at antero-lateral left ventricular from through the anterior breast. MI and fibrosis region were observed HE azan staining, and CX43 was determined by anti-CX43 immunostaining. Unipolar electrodes were employed for epicardial potential mapping. By the irradiation of heavy ion beam increased conductivity of and year-long induced CX43 whole the heart was observed 2 weeks after the irradiation in both mRNA and protein. In-vivo epicardial potential mapping on the free wall in MI hearts revealed reduced conduction velocity, whereas dispersion of the activation-recovery interval (ARI) was increased compared with controls, and these changes were reversed by irradiation.1) Kamada at al. Lancet Oncol 2015; 16: e93-1002) Amino et al. Am J Physiol Heart Circ Physiol 2010; 298: H1014-21
15th International Congress of Radiation Research

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