P wave polarity during pacing in pulmonary veins.

Abstract

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. 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. 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.