title: Characteristics and catheter ablation of focal atrial tachycardia originating from the interatrial septum.
abstract: BACKGROUND
  Ablation of focal atrial tachycardia (AT) originating from the interatrial septum (IAS) is challenging because of its complex anatomy.
  
  
  METHODS
  We studied the electrocardiographic and electrophysiologic characteristics of focal, septal AT in seven patients who underwent successful ablation.
  
  
  RESULTS
  The site of successful ablation was at the site of earliest activation on the right side of the IAS in three patients and on the left side in four patients, >1cm away from the centre of the fossa ovalis in the septum secundum. A negative or +/- versus a positive or -/+ P wave in lead V1 during AT accurately predicted a right- versus left-sided origin of the AT, respectively. In the four left septal AT cases, right atrial activation mapping opposite the site of successful ablation revealed the presence of a small, low-frequency potential followed by a larger, high-frequency potential. In contrast, a high-frequency potential was not preceded by a low-frequency potential in the three right septal AT cases.
  
  
  CONCLUSIONS
  Septal AT may originate from either side of the septum secundum. The P wave polarity in lead V1 accurately predicted the side of the IAS that the AT originated from. Left septal AT is characterised by the recording of double potentials reflecting far-field activation of the left-sided IAS, followed by near-field activation of the right-sided IAS, when recording from its right side, opposite the AT origin. These observations are particularly relevant when mapping an apparent right septal AT.
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan. Electronic address: kanekoy@gunma-u.ac.jp.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kaneko
authors.affiliation: Division of Cardiology, International Medical Center, Saitama Medical University, Hidaka, Saitama, Japan.
authors.forename: 'Ritsushi
authors.initials: '
authors.lastname: Kato
authors.affiliation: Department of Cardiology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Saitama, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Nakahara
authors.affiliation: Department of Cardiology, Tokushima University, Tokushima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tobiume
authors.affiliation: Department of Cardiology, Ogaki Municipal Hospital, Ogaki, Gifu, Japan.
authors.forename: Itsuro
authors.initials: I
authors.lastname: Morishima
authors.affiliation: Heart Center Arrhythmia Unit, Kasukabe Chuo General Hospital, Kazukabe, Saitama, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Tadanobu
authors.initials: T
authors.lastname: Irie
authors.affiliation: Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Kengo Fukushima
authors.initials: KF
authors.lastname: Kusano
authors.affiliation: Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Kamakura
authors.affiliation: Division of Cardiology, International Medical Center, Saitama Medical University, Hidaka, Saitama, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Nagase
authors.affiliation: Department of Cardiology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Saitama, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Takayanagi
authors.affiliation: Division of Cardiology, International Medical Center, Saitama Medical University, Hidaka, Saitama, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kurabayashi
mesh_terms: D000328:Adult; D000368:Aged; D054087:Atrial Septum / Q000503:physiopathology* / Q000601:surgery*; D054849:Cardiac Electrophysiology; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013612:Tachycardia, Ectopic Atrial / Q000503:physiopathology* / Q000601:surgery*
keywords: Atrial septum; Cardiac electrophysiology; Ectopic atrial tachycardia; Electrical catheter ablation; Electrocardiogram