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Inducibility of Ventricular Arrhythmia 1 Year Following Treatment with Heavy Ion Irradiation in Dogs with Myocardial Infarction
Author(s) -
AMINO MARI,
YOSHIOKA KOICHIRO,
FURUSAWA YOSHIYA,
TANAKA SACHIE,
KAWABE NOBORU,
HASHIDA TADASHI,
TSUKADA TERUYO,
IZUMI MASAKO,
INOKUCHI SADAKI,
TANABE TERUHISA,
IKARI YUJI
Publication year - 2017
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/pace.13031
Subject(s) - medicine , myocardial infarction , cardiology , qrs complex , electrocardiography , ejection fraction , signal averaged electrocardiogram , heart failure
Background Targeted external heavy ion irradiation (THIR) of rabbit hearts 2 weeks after myocardial infarction (MI) reduced the vulnerability of fatal ventricular tachyarrhythmias (VT/VF) in association with the increased connexin43 (Cx43). Increased Cx43 was maintained for at least 1 year in normal rabbits, but the long‐term antiarrhythmic effects in the MI model are unknown. We investigated the propensity for late potentials and VT/VF inducibility. Methods Intracoronary injection of microspheres was performed to induce nontransmural MI in anesthetized eight beagles. Four beagles were treated with THIR ( 12 C 6+ , 15 Gy) 2 weeks later (MI + THIR group), and four without THIR served as controls (MI group). Signal‐averaged electrocardiography, programmed electrical stimulation, immunohistochemical analysis, and echocardiograms were performed at 1 year. Results Filtered QRS duration was exacerbated after MI and remained unchanged for 1 year in the MI group (118 ± 1.4 ms), but significantly returned toward baseline in the MI + THIR group (109 ± 6.9 ms). Similarly, root mean square voltage of the last 40 ms was exacerbated after MI, but recovered after THIR. VT/VF inducibility decreased to 25% in the MI + THIR group compared with 100% in the MI group. Immunostaining Cx43 expression in cardiac tissues significantly increased by 24–45% in the MI + THIR group. Left ventricular ejection fractions remained within the normal range in both groups. Conclusion A single exposure of the dog heart to 12 C irradiation attenuated vulnerability to ventricular arrhythmia after the induction of MI for at least 1 year through the modulation of Cx43 expression.