A CASE OF TACHYCARDIA-INDUCED CARDIOMYOPATHYCAUSED BY AN ECTOPIC ATRIAL TACHYCARDIA ORIGINATING FROM THE RIGHT ATRIAL APPENDAGE

摘要

A 29-year-old man was referred to our hospital because of palpitation and dyspnea. An electrocardiogram revealed regular tachycardia at the rate of 180 bpm with an ectopic P wave. This tachycardia was resistant to several drugs and DC shock, and was diagnosed as an ectopic atrial tachycardia (EAT) with an abnormal automaticity. The chest X-ray showed mild pulmonary congestion and an echocardiography found a marked decrease of the left ventricular ejection fraction. Therefore, the rate control by verapamil and propranorol was initially chosen. However, EAT could not be fully controlled and the patient was getting worse day by day. Therefore, ablation using an electro-anatomical mapping system was performed. The isochronal mapping indicated a focus of EAT originating from the right atrial appendage. Thus the earliest activation sites were ablated by radio-frequency (RF) energy. However, EAT only repeated a transient acceleration of the rate during RF application and could not be completely eliminated. Fortunately, the rate control became easier after ablation and the patient was gradually improved. Finally, his cardiac function was restored, though ectopic pacemaker still remained. This case might have required AVN ablation and pacemaker implantation or surgical cryoablation if the rate control had been impossible.