title: Focal atrial tachycardia arising from the mitral annulus: electrocardiographic and electrophysiologic characterization.
abstract: OBJECTIVE
  The study was done to characterize the electrocardiographic and electrophysiologic features of focal atrial tachycardia originating at the mitral annulus (MA).
  
  
  BACKGROUND
  Though the majority of left atrial tachycardias originate around the ostia of the pulmonary veins, only isolated reports have described focal tachycardia originating from the MA.
  
  
  METHODS
  Seven patients of a consecutive series of 172 patients undergoing radiofrequency ablation for focal atrial tachycardia are reported. Electrophysiologic study involved catheters positioned along the coronary sinus (CS), crista terminalis (CT), His bundle, and a mapping/ablation catheter.
  
  
  RESULTS
  All seven patients had tachycardia foci originating from the superior region of the MA in close proximity to the left fibrous trigone and mitral-aortic continuity. These foci demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P-wave morphology in the precordial leads typically showed a biphasic pattern, with an inverted component followed by an upright component. The P-wave was consistently of low amplitude in the limb leads. Earliest endocardial activity occurred at the His bundle region in all seven patients. In general, CS activation was proximal to distal, and mid-CT activation was earlier than high or low CT. Ablation was successful at the superior aspect of the MA in all patients.
  
  
  CONCLUSIONS
  The MA is an unusual but important site of origin for focal atrial tachycardia, with a propensity to be localized to the superior aspect. It can be suspected as a potential anatomic site of tachycardia origin from analysis of P-wave morphology and the atrial endocardial activation sequence map. Using mapping targeted to anatomic structures achieved a high success rate for ablation.
authors.affiliation: Department of Cardiology, Royal Melbourne Hospital, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kistler
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.forename: Azlan
authors.initials: A
authors.lastname: Hussin
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Morton
authors.forename: Jitendra K
authors.initials: JK
authors.lastname: Vohra
authors.forename: Paul B
authors.initials: PB
authors.lastname: Sparks
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kalman
mesh_terms: D000328:Adult; D000368:Aged; D017115:Catheter Ablation; D004452:Echocardiography; D004594:Electrophysiology; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D017063:Outcome Assessment, Health Care; D012720:Severity of Illness Index; D013612:Tachycardia, Ectopic Atrial / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D013997:Time Factors