EN
A case of a dog with symptoms of weakness and cough caused by very rapid atrial tachycardia (270 bpm) was presented. Electrocardiography showed P wave preceded, narrow QRS complex incessant tachycardia. Echocardiography showed enlargement of both atria and ventricles. Tachycardia-induced cardiomyopathy resulting from permanent atrial tachycardia was diagnosed. The dog was ineffectively treated with metoprolol, digoxin, and amiodarone. The electrophysiological study revealed atrial tachycardia from the coronary sinus ostium. Radiofrequency catheter ablation was performed inferiorly to the coronary sinus ostium and tachycardia was successfully interrupted. After 5 d, electrocardiography showed a recurrence of sustained atrial tachycardia with a rate of 220 bpm (beats per minute) but of different P wave morphology. The electrophysiological study revealed atrial tachycardia from the same region of right atrium. Once again radiofrequency catheter ablation was successfully performed in the roof of coronary sinus ostium and tachycardia was not inducible in electrophysiological study. In the 3 month follow-up, Holter monitoring confirmed sinus rhythm in this dog. Echocardiography showed normal size atria and ventricles, normal shortening faction, and normal left ventricular ejection fraction.