title: Atrial tachycardia originating from the upper left atrial septum: demonstration of transseptal interatrial conduction using the infolded atrial walls.
abstract: We report a rare case of atrial tachycardia (AT) originating from the upper left atrial septum. Electroanatomic mapping of both atria demonstrated that the earliest atrial activation during AT occurred at the upper left atrial septum 26 msec before the onset of the P wave, followed by the mid-right atrial septum (10 msec before the onset of the P wave) and then the upper right atrial septum just adjacent to the left septal AT site (1 msec before the onset of the P wave), indicating detour pathway conduction from the upper left to the upper right atrium. Embryologically, it was suggested that the superior components of the secondary atrial septum are made by the infolded atrial walls and could develop a transseptal detour pathway involving the left-side atrial septal musculature, the superior rim of the oval fossa and the right-side atrial septal musculature. A single radiofrequency application targeting the upper left atrial septum successfully abolished the AT.
authors.affiliation: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. kkumagai@cardio.med.tohoku.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Kumagai
authors.forename: Fumio
authors.initials: F
authors.lastname: Suzuki
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aonuma
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimokawa
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation; D005260:Female; D006325:Heart Atria; D006329:Heart Conduction System / Q000503:physiopathology*; D006346:Heart Septum / Q000503:physiopathology*; D006801:Humans; D013612:Tachycardia, Ectopic Atrial / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery