title: The effects of pulmonary vein isolation on the morphology of p waves: the contribution of pulmonary vein muscle excitation to the formation of p waves.
abstract: BACKGROUND
  Although the pulmonary veins have been demonstrated to play an important role in initiating and perpetuating atrial fibrillation, the role that cardiac muscle tissue in the pulmonary veins plays regarding the formation of P wave remains to be elucidated. We sought to clarify the contribution of pulmonary vein cardiac muscles to the formation of P waves by analyzing the P loops/waves in patients with atrial fibrillation.
  
  
  METHODS
  The subjects in this study consisted of 21 patients (mean age, 57 +/- 10 years) with drug-refractory, paroxysmal atrial fibrillation who had undergone a segmental ostial isolation of all four pulmonary veins from the left atrium. Vectorcardiograms, intracardiac electrograms, and electrocardiograms (ECGs) were recorded before and after pulmonary vein isolation.
  
  
  RESULTS
  The morphology of P waves changed after pulmonary vein isolation procedures with a significant increase in the maximal amplitude of both the leftward force in lead x and the anterior force in lead z (P < 0.05). The middle part (second one of three parts) of P loop on the horizontal plane shifted anteriorly and leftward after pulmonary vein isolation. Intracardiac electrograms in the pulmonary veins demonstrated the averaged activation times of all four pulmonary veins to range from 40% to 84% of the P duration.
  
  
  CONCLUSIONS
  The excitation of cardiac muscle tissue, which has migrated to the pulmonary veins, was thus found to play an important role in the formation of the middle part of the P wave/loop.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo 105-8461, Japan. datet@jikei.ac.jp
authors.forename: Taro
authors.initials: T
authors.lastname: Date
authors.forename: Teiichi
authors.initials: T
authors.lastname: Yamane
authors.forename: Keiichi
authors.initials: K
authors.lastname: Inada
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Matsuo
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kanzaki
authors.forename: Satoru
authors.initials: S
authors.lastname: Miyanaga
authors.forename: Kenri
authors.initials: K
authors.lastname: Shibayama
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Ikuo
authors.initials: I
authors.lastname: Taniguchi
authors.forename: Seibu
authors.initials: S
authors.lastname: Mochizuki
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000601:surgery*; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins / Q000503:physiopathology* / Q000601:surgery*