title: [Spontaneous variability of ventricular extrasystole in chronic Chagas cardiopathy].
abstract: OBJECTIVE
  To study the spontaneous variability of single (VPCs) and coupled (CVPCs) in patients with chronic Chagas' disease (CCD).
  
  
  METHODS
  Twenty patients with CCD, 14 male, in class I and II NYHA, with frequent VPCs and VCPCs, free of drug therapy were studied. 21 hour Holter monitoring was done for 4 subsequent days. The data analysis assessed the variation in the frequency of VPCs and CVPCs between patients, seven hour periods one hour periods in a hierarchical model by a Poisson process.
  
  
  RESULTS
  a) the frequency of VPCs follows a circadian rhythm, closely related to the hourly variations of the mean heart rate; b) disregarding the heart rate influence on the variability of the ventricular arrhythmia, its behavior was at random and unpredictable; c) the minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous variability was 121.86% for seven-hour, 58.42% for 21-hour and 38.45% for 42-hour electrocardiographic monitoring periods; d) the same approach for the VCPCs revealed values of 133.6%, 63.21% and 41.3% respectively.
  
  
  CONCLUSIONS
  The large variability of ventricular arrhythmia in CCD during a 24 hour period makes necessary observations always longer. The minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous variability might be 58.42% for two 21-hour electrocardiography monitoring periods.
authors.affiliation: Instituto do Coração, Hospital das Clínicas-FMUSP.
authors.forename: C J
authors.initials: CJ
authors.lastname: Grupi
authors.forename: E A
authors.initials: EA
authors.lastname: Sosa
authors.forename: J F
authors.initials: JF
authors.lastname: De Carvalho
authors.forename: R H
authors.initials: RH
authors.lastname: Antonelli
authors.forename: G
authors.initials: G
authors.lastname: Bellotti
authors.forename: F
authors.initials: F
authors.lastname: Pileggi
mesh_terms: D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D005117:Cardiac Complexes, Premature / Q000188:drug therapy / Q000503:physiopathology*; D002598:Chagas Cardiomyopathy / Q000188:drug therapy / Q000503:physiopathology*; D002908:Chronic Disease; D002940:Circadian Rhythm; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep; D014851:Wakefulness
chemical_list: D000889:Anti-Arrhythmia Agents
vernacular_title: Variabilidade espontânea da extra-sistolia ventricular na cardiopatia chagásica crônica.