title: Electrophysiologic characteristics of ventricular arrhythmias arising from the aortic mitral continuity-potential role of the conduction system.
abstract: BACKGROUND
  Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown.
  
  
  METHODS
  Procedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate.
  
  
  RESULTS
  Of the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs; 26.1 ± 10.9% vs. 14.9 ± 10.1%, P = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 milliseconds vs. 33.1 ± 8.8 milliseconds, P = 0.03), lower pace map scores (8.7 ± 1.6 vs. 11.4 ± 0.8, P = 0.001), and a trend toward shorter V-H intervals during VA (32.1 ± 38.6 milliseconds vs. 76.3 ± 11.1 milliseconds, P = 0.06) as compared to those without PP. A strong and positive correlation was found between V-H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R(2) = 0.97, t = 13.7, P < 0.001) but not in those without PPs.
  
  
  CONCLUSIONS
  Local EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success.
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, Hong Kong.
authors.forename: Jo Jo
authors.initials: JJ
authors.lastname: Hai
authors.forename: Anwar A
authors.initials: AA
authors.lastname: Chahal
authors.forename: Paul A
authors.initials: PA
authors.lastname: Friedman
authors.forename: Vaibhav R
authors.initials: VR
authors.lastname: Vaidya
authors.forename: Faisal F
authors.initials: FF
authors.lastname: Syed
authors.forename: Christopher V
authors.initials: CV
authors.lastname: DeSimone
authors.forename: Sudip
authors.initials: S
authors.lastname: Nanda
authors.forename: Peter A
authors.initials: PA
authors.lastname: Brady
authors.forename: Malini
authors.initials: M
authors.lastname: Madhavan
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Cha
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: McLeod
authors.forename: Siva
authors.initials: S
authors.lastname: Mulpuru
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Munger
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Packer
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Asirvatham
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000503:physiopathology* / Q000601:surgery; D002036:Bundle of His / Q000503:physiopathology; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006352:Heart Ventricles / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D008943:Mitral Valve / Q000503:physiopathology* / Q000601:surgery; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000601:surgery
keywords: aortomitral continuity; arrhythmogenic substrate; conduction system; ventricular arrhythmias