title: A quantitative and qualitative analysis of the virtual unipolar electrograms from non-contact mapping of right or left-sided outflow tract premature ventricular contractions/ventricular tachycardia origins.
abstract: OBJECTIVE
  This study was conducted to examine the virtual unipolar electrogram configuration of right/left outflow tract (OT) premature ventricular contraction (PVC)/ventricular tachycardia (VT) origins obtained from a non-contact mapping system (NCMS).
  
  
  METHODS
  The subjects consisted of 30 patients with OT-PVCs/VT who underwent NCMS-guided ablation. We evaluated the virtual unipolar electrograms of the origin on 3D right ventricular (RV)-OT isochronal maps.
  
  
  RESULTS
  Successful ablation was achieved from the RV in 20 patients (RVOT group), and it failed in 10 (non-RVOT group: including left-sided/pulmonary artery/deep RVOT foci). On the virtual unipolar electrograms, the earliest activation (EA) preceded the QRS onset by 11.2 ± 2.6 ms in the RVOT group and by 7.4 ± 10.5 ms in the non-RVOT group (P = 0.138). The negative slope of the electrogram at the EA site (EA slope(5)), quantified by the virtual unipolar voltage amplitude 5 ms after the EA onset, was significantly steeper in the RVOT group than in the non-RVOT group (0.66 ± 0.52 mV vs. 0.14 ± 0.17 mV, P = 0.005). Cutoff values for the EA-to-QRS onset time and EA slope(5) of ≥ 8 ms and >0.3 mV, respectively, completely differentiated the RVOT group from the non-RVOT group. A lesser EA slope(5) was associated with a greater radiofrequency energy delivery required to terminate RVOT-PVCs/VT.
  
  
  CONCLUSIONS
  These demonstrate the importance of the virtual unipolar electrograms from OT-PVC/VT origins obtained with the NCMS. The virtual EA predicts both successful and potentially difficult ablation sites from the RV side.
authors.affiliation: Division of Cardiology, Department of Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kami machi, Itabashi-ku, Tokyo 173-8610, Japan. yasuwo128@yahoo.co.jp
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okumura
authors.forename: Ichiro
authors.initials: I
authors.lastname: Watanabe
authors.forename: Toshiko
authors.initials: T
authors.lastname: Nakai
authors.forename: Kimie
authors.initials: K
authors.lastname: Ohkubo
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kofune
authors.forename: Sonoko
authors.initials: S
authors.lastname: Ashino
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kofune
authors.forename: Koichi
authors.initials: K
authors.lastname: Nagashima
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hiro
authors.forename: Akio
authors.initials: A
authors.lastname: Hirata
authors.forename: Mizuki
authors.initials: M
authors.lastname: Nikaido
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirayama
mesh_terms: D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006352:Heart Ventricles / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000150:complications* / Q000175:diagnosis* / Q000601:surgery*; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*