title: [Torsades de Pointes: analysis of 105 episodes].
abstract: OBJECTIVE
  To analyze episodes of Torsades de Pointes (TP), in search of its electrocardiographic characteristics.
  
  
  METHODS
  We analyzed 105 episodes of TP, in 4 patients using quinidine and diuretics, recorded by 24-hour Holter monitoring. The following parameters were studied; ventricular repolarization out of TP, rhythm disturbances before TP; EKG characteristics of the onset, the bouts and the end of the TP.
  
  
  RESULTS
  Ventricular repolarization, out of the TP, was abnormal, with the presence of U-waves at the end of the T-waves, resulting in prolongation of the QT (QU) interval. The U-wave voltage was noted to be cycle-length dependent. Ventricular bigeminy preceded TP in 100 episodes (95%) and the mean interval between both parameters was 18 +/- 16 min. The onset of the TP episodes showed the "short/long/short cycle rule", hereby called "pre-pause cycle", "preparing cycle" and "trigger cycle" respectively. The rotatory QRS-T morphology around the baseline, was seen in 75% of episodes, at the beginning or throughout the bout. Monomorphic ventricular tachycardia pattern was seen in the other 25% of episodes. Termination of bouts was sudden in all cases, and persistent ventricular bigeminy led to another bout in 90 episodes (85%).
  
  
  CONCLUSIONS
  In TP patients, there is enlargement of QT intervals mostly due to U-waves appearance. The U-waves seen in these cases, probably have an important role in the genesis of TP and are probably related to ventricular after-potentials (triggered activity). Ventricular bigeminy is a premonitory sign of TP in patients using class 1A antiarrhythmic drugs. Persistent ventricular bigeminy post-TP episodes is a strong indicator of another bout of TP. The onset of TP is more important than its morphology for the correct diagnosis of this arrhythmia.
authors.affiliation: Hospital Procardíaco/Pró-Ritmo, Rio de Janeiro.
authors.forename: I G
authors.initials: IG
authors.lastname: Maia
authors.forename: R
authors.initials: R
authors.lastname: Sá
authors.forename: P A
authors.initials: PA
authors.lastname: Alves
authors.forename: J C
authors.initials: JC
authors.lastname: Ribeiro
authors.forename: P H
authors.initials: PH
authors.lastname: Fernandes
authors.forename: O
authors.initials: O
authors.lastname: Guarçoni
authors.forename: R
authors.initials: R
authors.lastname: Bassan
authors.forename: H F
authors.initials: HF
authors.lastname: Dohmann
mesh_terms: D000368:Aged; D004232:Diuretics / Q000627:therapeutic use; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011802:Quinidine / Q000627:therapeutic use; D012189:Retrospective Studies; D016171:Torsades de Pointes / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology
chemical_list: D004232:Diuretics; D011802:Quinidine
vernacular_title: Torsades de Pointes: análise de 105 episódios.