title: [Clinical observation on pause-dependent long QT syndrome and torsade de pointes ventricular tachycardia].
abstract: Ten patients with long QT syndromes (LQTs) and torsade de pointes (Tdp) were evaluated. The following features were noticed: (1) Serum potassium concentration was reduced in 5 of 10 patients (50.0%, mean value 3.0 mmol/L); (2) The QT interval (mean value 0.50s) was significantly prolonged in all patients; (3) A flat and wide T wave, an abnormal increase in U wave amplitude close to the end or the peak of the T wave and these changes were accentuated by pause or a sudden deceleration in ventricular rhythm; (4) The critical beat of Tdp inevitably started after the peak of the T wave of a markedly prolonged QT interval. Cycle lengths preceding torsade de pointes were shown in a pattern of short cycle-long QT-"late premature ventricular contraction" initiating sequence changes.
authors.affiliation: Fu Wai Hospital, Chinese Academy of Medical Sciences, Beijing.
authors.forename: Y C
authors.initials: YC
authors.lastname: Song
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006801:Humans; D008133:Long QT Syndrome / Q000503:physiopathology* / Q000628:therapy; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D016171:Torsades de Pointes / Q000503:physiopathology* / Q000628:therapy
chemical_list: D011188:Potassium