Basic/Translational Science -> Whole Animal Electrophysiology and Pharmacology (includes Neurohumoral Modulation) D-PO05 - Poster Session V (ID 39) Poster

D-PO05-055 - BiologicalEffect Of Carbon-radiotherapy For Vt Suppression In Non-ischemic Rabbit Heart (ID 524)

Abstract

Background: Radio-ablation for VT is an analogy from catheter ablation and is based on the idea of ​​causing fibrosis of the arrhythmic substrate and blocking abnormal conduction pathways, aiming for “cell-ablation” by radiation (Phllip et al. NEJM 2017). However, the onset of the antiarrhythmic effect is clearly faster than the time when fibrosis occurs, and has a certain effect immediately after the treatment and cannot be explained by the above-mentioned idea.
Objective: The aim of this study is to investigate the Connexin 43 upregulation and sympathetic nerve suppression by heavy-ion beam using a non-ischemic diseased heart without regional fibrosis.
Methods: Three-year-old rabbits were fed high fat and cholesterol chow(HC model) for 14 weeks(n=8). Targeted single irradiation of 15Gy heavy-ion beam (THIR) was applied on the left ventricle at 12 weeks(HC+THIR group, n=4). Rabbits without THIR were used as control(HC group, n=4). In-vivo electrophysiological study and immunostaining analysis were performed.
Results: Serum cholesterol levels(mg/dL) were 1569 +/- 327 in the HC+THIR group and 1545 +/- 386 in the HC group. UCG findings such as EF, E/A, EDT parameters were not significant in both groups. Ventricular late potentials detected by QRS-wave signal-averaged electrocardiography showed significant large root mean square voltages in the last 20 ms(microV) in the HC+THIR group compared with the HC group(122.3 +/- 19.5 vs 13.6 +/- 9.3\7), which means less conduction delay in the HC+THIR group. VT vulnerability was lower in the HC+THIR group(1/4 vs 4/4). Immunoreactive Cx43-signals in the ventricle were significantly increased by 78.2% and nerve density of neural growth factor, growth-associated protein 43(NGF-GAP43) was significantly decreased by 58.9% in the HC+THIR group.
Conclusion: Heavy-ion beam reduced VT vulnerability in aged-rabbits with hypercholesterolemia, which might be related to the ventricular conduction recovery due to connexin upregulation and inhibiting the sympathetic hyperinnervation.
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