title: [Acute effects of propafenone in patients with ventricular pre-excitation].
abstract: OBJECTIVE
  To evaluate the electrophysiological effects of intravenous propafenone in the anterograde and retrograde effective refractory period of the accessory pathways (AP), in patients with Wolff-Parkinson-White syndrome.
  
  
  METHODS
  Forty symptomatic patients were studied. All patients were undergone to electrophysiologic study at baseline and after IV propafenone (2.0mg/kg). Drug effects were analysed according to the basal state of the anterograde and retrograde effective refractory periods of the AP > < 270ms.
  
  
  RESULTS
  The mean anterograde and retrograde effective refractory periods of the AP were 275 +/- 76ms and 264 +/- 44ms at the control and 462 +/- 190ms and 438 +/- 184ms after drug respectively (p < 0.01 in both situations). The mean anterograde effective refractory period of the AV node was 236 +/- 40ms (control) and 276 +/- 57ms (post-drug)- p < 0.05. The mean atrial and right ventricular effective refractory period in the control were 210 +/- 23ms and 240 +/- 34ms passing to 215 +/- 24ms and 250 +/- 40 ms after drug respectively (p = ns). After drug, complete anterograde and retrograde block of the AP, occurred in 15 (42%) and 12 (35%) patients respectively. Out of 15 patients with complete anterograde block of the AP, 11 had anterograde effective refractory period of the AP > 270ms and 4, < 270ms (p < 0.02). Out of 12 patients with complete retrograde block of the AP after drug, 4 had retrograde effective refractory period > 270ms and 8, < 270ms (p: ns).
  
  
  CONCLUSIONS
  Propafenone caused significant increase in the anterograde and retrograde effective refractory periods of the AP. There was a tendency of the drug to show better effectiveness in patients with anterograde effective refractory period of the AP > 270ms. This results were not seen in relation to the retrograde effective refractory period of the AP.
authors.affiliation: Hospital de Cardiologia de Laranjeiras, Rio de Janeiro.
authors.forename: I G
authors.initials: IG
authors.lastname: Maia
authors.forename: F
authors.initials: F
authors.lastname: Cruz Filho
authors.forename: M L
authors.initials: ML
authors.lastname: Fagundes
authors.forename: L H
authors.initials: LH
authors.lastname: Loyola
authors.forename: J
authors.initials: J
authors.lastname: Pimenta
authors.forename: A M
authors.initials: AM
authors.lastname: Lorga
mesh_terms: D000293:Adolescent; D000328:Adult; D001283:Atrioventricular Node / Q000002:abnormalities / Q000187:drug effects; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000139:chemically induced; D006801:Humans; D008297:Male; D008875:Middle Aged; D011405:Propafenone / Q000008:administration & dosage / Q000494:pharmacology*; D013614:Tachycardia, Paroxysmal / Q000139:chemically induced; D014927:Wolff-Parkinson-White Syndrome / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D011405:Propafenone
vernacular_title: Efeitos agudos da propafenona em pacientes com pré-excitação ventricular.