title: P wave polarity during pacing in pulmonary veins.
abstract: BACKGROUND
  Recent studies have demonstrated that premature depolarizations that trigger atrial fibrillation often arise in pulmonary veins. The purpose of this study was to evaluate whether P wave polarity is helpful in distinguishing which of the 4 pulmonary veins is the site of origin of a premature depolarization.
  
  
  RESULTS
  In 28 patients without structural heart disease who underwent focal ablation of paroxysmal atrial fibrillation, P wave polarity on a 12-lead electrocardiogram (ECG) was analyzed during sinus rhythm, and during pacing at a cycle length of 500--600 ms in the high right atrium and within each of the 4 pulmonary veins. P waves were categorized as positive, negative, biphasic or isoelectric. A negative or biphasic P wave in lead I (sensitivity 85 %, specificity 71 %) or a positive P wave in V1 (sensitivity 85 %, specificity 89 %) were helpful in predicting a pulmonary venous site of origin as opposed to a right atrial site of origin. A positive P wave in lead II and III distinguished superior from inferior pulmonary veins (sensitivity 90 %, specificity 84 %). The sensitivity and specificity of negative or biphasic P waves in lead aVL in distinguishing a left from right pulmonary vein site of origin were 94 % and 42 %, respectively.
  
  
  CONCLUSIONS
  Analysis of P waves polarity may be helpful in localizing the pulmonary vein that is the site of origin of a premature depolarization. Among the 12 ECG leads, I, II, III, aVL, and V1 are the most helpful in regionalizing premature depolarizations arising in the pulmonary veins.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Hong Kong, Queen Mary Hospital.
authors.forename: H F
authors.initials: HF
authors.lastname: Tse
authors.forename: C P
authors.initials: CP
authors.lastname: Lau
authors.forename: K L
authors.initials: KL
authors.lastname: Lee
authors.forename: F
authors.initials: F
authors.lastname: Pelosi
authors.forename: H
authors.initials: H
authors.lastname: Oral
authors.forename: B P
authors.initials: BP
authors.lastname: Knight
authors.forename: S A
authors.initials: SA
authors.lastname: Strickberger
authors.forename: F
authors.initials: F
authors.lastname: Morady
mesh_terms: D000328:Adult; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011667:Pulmonary Veins / Q000502:physiology*; D012680:Sensitivity and Specificity