title: Electrophysiologic and clinical effects of oral encainide in paroxysmal atrioventricular node reentrant tachycardia.
abstract: The electrophysiologic effects of oral encainide (75 to 150 mg daily) were evaluated in 14 patients (6 male and 8 female, aged 49 +/- 9 years) with atrioventricular (AV) node reentrant tachycardia of the slow-fast type. The patients were studied in control conditions and after 2 to 12 days of treatment. Encainide increased the AH interval from 67 +/- 10 to 82 +/- 23 ms (p less than 0.02). Anterograde Wenckebach cycle length was increased in three patients, reduced in four, unchanged in one; it was not measurable in the remaining patients because tachycardia was induced. Retrograde Wenckebach periodicity increased from 307 +/- 71 to 401 +/- 92 ms (p less than 0.005) in all nine patients in whom it was measurable; complete retrograde block was observed in one patient. At the control study, tachycardia was induced in all patients, with a mean cycle length of 341 +/- 50 ms; after encainide, tachycardia was inducible in only 1 patient, with an increase in cycle length from 270 to 320 ms; in the other patients, tachycardia was not inducible because of a lack of retrograde (11 patients) or anterograde (2 patients) conduction. The mean plasma concentrations of encainide and its metabolites O-demethyl-encainide and 3-methoxy-O-demethyl-encainide measured in 13 patients during the repeat study were 161 +/- 304, 128 +/- 100 and 95 +/- 85 ng/ml, respectively; three poor metabolizers who presented a high concentration of the parent compound were observed in this series. All patients were discharged on encainide at a mean daily dose of 112 +/- 39 mg.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, University of Pavia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Chimienti
authors.forename: M
authors.initials: M
authors.lastname: Li Bergolis
authors.forename: M
authors.initials: M
authors.lastname: Moizi
authors.forename: J A
authors.initials: JA
authors.lastname: Salerno
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000813:Anilides / Q000008:administration & dosage / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D004594:Electrophysiology; D016700:Encainide; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000188:drug therapy*; D013617:Tachycardia, Supraventricular; D013997:Time Factors
chemical_list: D000813:Anilides; D000889:Anti-Arrhythmia Agents; D016700:Encainide