心房細動から心房頻拍への移行など多彩な上室性頻拍を伴ったATP感受性リエントリー性心房頻拍の1例—心房局所的焼灼による心房頻拍，心房細動の根治

A Case of ATP Sensitive Intra-atrial Reentrant Tachycardia with Various Supraventricular Tachycardias Including a Transition from Atrial Fibrillation to Atrial Tachycardia

　症例は70歳，女性．心房細動から心房頻拍への移行を含む多彩な上室性不整脈を認めた．心房頻拍の停止には，ATP5mgの静注が有効であった．電気生理学的検査では，心房早期刺激にて心房頻拍が再現性をもって誘発された．心房刺激に対する反応から発生機序とたてリエントリーを考えた．最早期興奮部位を右房前壁中央部に認め，同部位にて心房波の分裂が記録された．高周波カテーテルアブレーションを行い心房頻拍のみならず心房細動も誘発されなくなった．心房の局所的焼灼が心房細動の根治につながったと考えられた．非発作時に認めていた心電図ST・T変化はアブレーション1週間後には改善された．本例は約8カ月間，臨床的に頻脈発作を認めていない．

　A 70-year-old woman was admitted to our hospitalfor the management of palpitation due to various supraventricular tachycardias. These tachycardias were able to be terminated by intravenous administration of ATP.

　The tachycadias were initiated and reproduced by atrial extrastimulation, and there was an inverse relationship between the coupling interval of an extrastimulus and the postextrastimulus interval.

　According to the results of electrophysiologic study, we diagnosed these tachycardias as intra-atrial reentrant tachycardia (IART). The induced atrial fibrillation frequently changed to atrial tachycardia.

　The earliest atrial activity during IART was recorded at the mid portion of the anterior right atrium and split potentials were observed at this site, where the IARTwas succesfully ablated. The electrophysiological study after ablation revealed neither induction of IART nor atrial fibrillation. It seems that radiofrequency catheter ablation at a focal site was effective in terminating not only IART but also atrial fibrillation.

　The electrocardiogram showed ST depression in sinus rhythm before ablation but this was normalized a week after ablation. Follow-up observation for 8 months shows no recurrence of atrial tachycardia and atrial fibrillation.