title: Left septal atrial tachycardia after open-heart surgery: relevance to surgical approach, anatomical and electrophysiological characteristics associated with catheter ablation, and procedural outcomes.
abstract: BACKGROUND
  Septal atrial tachycardia (AT) can occur in patients without structural heart disease and in patients with previous catheter ablation of atrial fibrillation. We aimed to assess septal AT that occurs after open-heart surgery.
  
  
  RESULTS
  This study comprised 20 consecutive patients undergoing catheter ablation of macroreentrant AT after open-heart surgery. Relevance to surgical approach, mechanisms, anatomic and electrophysiological characteristics, and outcomes were assessed. Septal AT was identified in 7 patients who had all undergone mitral valve surgery. All septal ATs were localized in the left atrial septum, whereas 10 of 13 nonseptal ATs originated from the right atrium. Patients with left septal AT had a thicker fossa ovalis (median, 4.0; 25th-75th percentile, 3.6-4.2 versus 2.3; 1.6-2.6 mm; P=0.006) and broader area of low voltage (<0.3 mV) in the septum than patients with nonseptal AT (82; 76-89 versus 31; 28%-36%; P=0.02). Repeated gradual prolongations of the tachycardia cycle length without change of the septal circuit were observed in all patients with septal AT (70; 63-100 versus 15; 10-40 ms; P=0.0008). Although ablation terminated all ATs, recurrence of targeted ATs was more frequent in patients with left septal AT during 30-month follow-up (71 versus 0%; P=0.001).
  
  
  CONCLUSIONS
  Left septal AT after open-heart surgery was characterized by a thicker septum, more scar burden in the septum, and repeated prolongations of the tachycardia cycle length during ablation. Such an arrhythmogenic substrate may interfere with transmural lesion formation by ablation and may account for higher likelihood of recurrence of left septal AT.
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Toru
authors.initials: T
authors.lastname: Adachi
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.). kentaroyo@nifty.com.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Takeyasu
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Keita
authors.initials: K
authors.lastname: Masuda
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Yukio
authors.initials: Y
authors.lastname: Sekiguchi
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Akira
authors.initials: A
authors.lastname: Sato
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tada
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nogami
authors.affiliation: From the Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan (T.A., K.Y., N.T., K.M., Y.S., A.S., A.N., K.A.); and Division of Cardiovascular Medicine, University of Fukui, Yoshida-gun, Japan (H.T.).
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aonuma
mesh_terms: D000328:Adult; D000368:Aged; D054087:Atrial Septum / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D017115:Catheter Ablation / Q000009:adverse effects; D018572:Disease-Free Survival; D018618:Echocardiography, Doppler, Color; D017548:Echocardiography, Transesophageal; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012008:Recurrence; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
keywords: atrial flutter; atrial septum; catheter ablation; heart surgery