title: [The circadian profile of ventricular extrasystole].
abstract: OBJECTIVE
  to determine the existence of circadian variability (CV) of single ventricular premature beats (VPBs) and study its relationship with the heart rate variation; to compare sub-groups of patients (Pts) with and without antiarrhythmic therapy and with ischemic cardiopathy versus a free structural cardiopathy group.
  
  
  METHODS
  retrospective study.
  
  
  METHODS
  the CV of VPBs was analyzed by Holter monitoring in 147 Pts, 93 male and 54 female with a mean age of 59 +/- 14.6. Seventy seven Pts were not taking antiarrhythmic drugs while 70 were doing it: Amiodarone 23, Propafenone 30, B-Blockers 9, Quinidine and Disopyramide 7, Flecainide 1. Sixty five Pts had ischemic cardiopathy and 37 were free of any structural abnormality. The selection criteria consisted in: 1--more than 100 VPBs/24h; 2--distribution over more than 12 hours; 3--absence of any hour with more than 35% of the total VPBs in the recording. Data were presented in a percentage form and the results evaluation was made by using single and two-harmonic regression models.
  
  
  RESULTS
  a CV was found to the single VPBs, with minimum values during the nocturnal period and maximum values in the morning, with a significant adjustment to the two-harmonic regression model, defined by the equation y = 4.2 - Q,559 sen (2 pi T/24) - 0.604 cos (2 pi T/24) - 0.417 sen (4 pi T/24) + 0,272 cos (4 pi T/24) (p < 0.001). A strong positive correlation was observed between VPBs and heart rate variability (r = 0.95; p < 0.001). The sub-groups of Pts, whether taking antiarrhythmic drugs or not, also showed a CV with a statistically significant two-harmonic regression pattern, with a major morning increase of VPBs in the antiarrhythmic group. The free structural cardiopathy sub-group displayed a best adjustment to the single harmonic regression model while the ischemic group exhibited a two-harmonic regression pattern.
  
  
  CONCLUSIONS
  a significant circadian variability of VPBs with a bi-modality expression was determined. The majority of the analyzed sub-groups showed the same kind of variation. A strong positive correlation with the heart rate variability was observed.
authors.affiliation: Serviço de Cardiologia, Hospital Distrital de Angra do Heroismo.
authors.forename: J P
authors.initials: JP
authors.lastname: Paisana
authors.forename: F
authors.initials: F
authors.lastname: Gomes
authors.forename: J
authors.initials: J
authors.lastname: Cruz
authors.forename: D
authors.initials: D
authors.lastname: Bonhorst
authors.forename: D
authors.initials: D
authors.lastname: Lopes
authors.forename: V
authors.initials: V
authors.lastname: Schneider
authors.forename: G
authors.initials: G
authors.lastname: Bruges
authors.forename: C
authors.initials: C
authors.lastname: Gil
mesh_terms: D000367:Age Factors; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D005117:Cardiac Complexes, Premature / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D016009:Chi-Square Distribution; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D016018:Least-Squares Analysis; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012189:Retrospective Studies; D012737:Sex Factors
chemical_list: D000889:Anti-Arrhythmia Agents