title: Electrophysiologic characteristics in initiation of paroxysmal atrial fibrillation from a focal area.
abstract: OBJECTIVE
  We investigated the electrophysiologic characteristics in the initiation of paroxysmal atrial fibrillation (PAF) from a focal area.
  
  
  BACKGROUND
  The electrophysiologic characteristics in the initiation of PAF are still not clear.
  
  
  METHODS
  The study group consisted of 77 patients (M/F = 65/12, age 66 +/- 12 years) with frequent episodes of PAF; we analyzed: 1) 15 cycle lengths of electrical activity before the onset of atrial fibrillation (AF); 2) coupling interval (CI) of the first ectopic beat just before the initiation of AF; and 3) the prematurity of an ectopic beat (prematurity index [PI] = CI/mean of preceding 15 cycle lengths).
  
  
  RESULTS
  A total of 111 episodes of sustained AF were identified. Two patterns of AF initiation were observed: group I (59/111, 53%) included the episodes preceded by cycle length oscillation, and group II (52/111, 47%) included the episodes initiated by a single ectopic beat with preceding cycle length relatively constant. The PI of group I episodes was significantly greater than that of group II (0.41 +/- 0.12 vs. 0.34 +/- 0.10, p < 0.01). The CI (267 +/- 54 ms vs. 217 +/- 55 ms, p < 0.05), AF1 (194 +/- 36 ms vs. 153 +/- 37 ms, p < 0.05) and PI (0.49 +/- 0.13 vs. 0.37 +/- 0.11, p < 0.01) of the AF episodes from the superior vena cava (SVC) were significantly longer and greater than those of AF episodes from pulmonary veins (PVs).
  
  
  CONCLUSIONS
  In patients with PAF originating from PVs or the SVC, two major initiating patterns were found. Moreover, the electrophysiologic characteristics in the initiation of AF originating from the SVC were also different from those of AF initiating from the PVs.
authors.affiliation: Department of Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan, Republic of China.
authors.forename: T M
authors.initials: TM
authors.lastname: Lu
authors.forename: C T
authors.initials: CT
authors.lastname: Tai
authors.forename: M H
authors.initials: MH
authors.lastname: Hsieh
authors.forename: C F
authors.initials: CF
authors.lastname: Tsai
authors.forename: Y K
authors.initials: YK
authors.lastname: Lin
authors.forename: W C
authors.initials: WC
authors.lastname: Yu
authors.forename: H M
authors.initials: HM
authors.lastname: Tsao
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: Y A
authors.initials: YA
authors.lastname: Ding
authors.forename: M S
authors.initials: MS
authors.lastname: Chang
authors.forename: S A
authors.initials: SA
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D018880:Atrial Premature Complexes / Q000145:classification / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D006332:Cardiomegaly / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology; D017115:Catheter Ablation; D016009:Chi-Square Distribution; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation / Q000379:methods; D005260:Female; D006325:Heart Atria; D006801:Humans; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins; D012720:Severity of Illness Index; D013997:Time Factors; D014683:Vena Cava, Superior