title: Electrocardiographic and electrophysiological characteristics in idiopathic ventricular arrhythmias originating from the papillary muscles in the left ventricle: relevance for catheter ablation.
abstract: BACKGROUND
  Idiopathic ventricular arrhythmias (VAs) can originate from the left ventricular papillary muscles (PAMs). This study investigated the electrophysiological characteristics of these VAs and their relevance for the results of catheter ablation.
  
  
  RESULTS
  We studied 19 patients who underwent successful catheter ablation of idiopathic VAs originating from the anterior (n=7) and posterior PAMs (n=12). Although an excellent pace map was obtained at the first ablation site in 17 patients, radiofrequency ablation at that site failed to eliminate the VAs, and radiofrequency lesions in a relatively wide area around that site were required to completely eliminate the VAs in all patients. Radiofrequency current with an irrigated or nonirrigated 8-mm-tip ablation catheter was required to achieve a lasting ablation of the PAM VA origins. During 42% of the PAM VAs, a sharp ventricular prepotential was recorded at the successful ablation site. In 9 (47%) patients, PAM VAs exhibited multiple QRS morphologies, with subtle, but distinguishable differences occurring spontaneously and after the ablation. In 7 (78%) of those patients, radiofrequency lesions on both sides of the PAMs where pacing could reproduce an excellent match to the 2 different QRS morphologies of the VAs were required to completely eliminate the VAs.
  
  
  CONCLUSIONS
  Radiofrequency catheter ablation of idiopathic PAM VAs is challenging probably because the VA origin is located relatively deep beneath the endocardium of the PAMs. PAM VAs often exhibit multiple QRS morphologies, which may be caused by a single origin with preferential conduction resulting from the complex structure of the PAMs.
authors.affiliation: Division of Cardiovascular Disease and Department of Pathology, University of Alabama at Birmingham, 1670 University Blvd., 1530 3rd Ave. S., Birmingham, AL 35294-0019, USA. takumi-y@fb4.so-net.ne.jp
authors.forename: Takumi
authors.initials: T
authors.lastname: Yamada
authors.forename: Harish
authors.initials: H
authors.lastname: Doppalapudi
authors.forename: H Thomas
authors.initials: HT
authors.lastname: McElderry
authors.forename: Taro
authors.initials: T
authors.lastname: Okada
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Murakami
authors.forename: Yasuya
authors.initials: Y
authors.lastname: Inden
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshida
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Murohara
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Epstein
authors.forename: Vance J
authors.initials: VJ
authors.lastname: Plumb
authors.forename: Silvio H
authors.initials: SH
authors.lastname: Litovsky
authors.forename: G Neal
authors.initials: GN
authors.lastname: Kay
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000295:instrumentation; D004452:Echocardiography; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D010210:Papillary Muscles / Q000503:physiopathology* / Q000601:surgery; D011237:Predictive Value of Tests; D015641:Radiography, Interventional; D012008:Recurrence; D012086:Reoperation; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional