Isopotential mapが起源予測に有用であった左房起源異所性心房頻拍に対し，経心房中隔アプローチにてカテーテル・アブレーションに成功した1例

A Case of Successful Ablation of Ectopic Atrial Tachycardia whose Origin was Detected by Isopotential Mapping

　症例は20歳，男性．17歳時，心房頻拍にて心不全の既往があり薬物治療を受けていた．しかし，心房頻拍は薬剤抵抗性でありカテーテル・アブレーション目的にて入院となった．アブレーション前の頻拍中の体表面電位図によるisopotential mapにて，左房起源の頻拍が予測された．電気生理検査にて自動能亢進を機序とする左房起源異所性心房頻拍と診断し，ロングシースを介し経心房中隔的に左房内のマッピング後，右上肺静脈流入部への通電にてアブレーションに成功した．左房起源の心房頻拍に対するアブレーションでは，brock—enbrough法を含めた経心房中隔アプローチが必要となる．このため，アブレーション前の頻拍起源の予測は重要となるが，本症例ではisopotential mapにて左房起源の予測が可能であった．また，左房右上肺静脈流入部への通電も合併症なく安全に施行することができた．

A 20-year-old man with ectopic atrial tachycardia, the origin of which was detected by isopotential map-ping underwent radiofrequency ablation of the origin via a transseptal approach. At the age of 17, tachycardia -induced congestive heart failure developed and medical treatment was begun. However. the tachycardia was refractory to medical therapy. Before the ablation pro-cedure, a body surface map was recorded during atrial tachycardia from 87 points. An isopotential map was constructed from the points, and the site of the earliest atrial activation was found to be in the left atrial region. On electrophysiological study. tachycardia appeared to be due to atrial automaticity. The transseptal mapping showed that the site of the earliest atrial activation was in the right superior pulmonary vein region of the left atrium. Radiofrequency energy was delivered to the region, with termination of the tachycardia. The isopotential map was useful for determinating the origin of atrial tachycardia. Transseptal catheter ablation of the right superior pulmonary vein region of the left atrium was safe and effective in treating this patient with drug -refractory ectopic atrial tachycardia of left atrial origin.