title: Ventilatory response during exercise among chronic Chagas cardiopathy patients.
abstract: OBJECTIVE
  The change in slope of the .VE/.VCO2 curve with time during exercise (.VE/.VCO2 slope) has been recommended as a parameter for analyzing the ventilatory response during exercise among patients with heart failure of different etiologies. The aim of this work was to evaluate the ventilatory response among patients with chronic Chagas cardiopathy.
  
  
  METHODS
  Forty-eight patients, divided into four groups according to the Los Andes clinical/hemodynamic classification, were studied. They were also classified according to peak oxygen uptake (peak .VO2) for a second analysis. The results from the patients were compared with results from a control group consisting of 21 healthy male volunteers (no Chagas disease). Exercise was performed on a cycle ergometer with loads increasing at the rate of 12.5 watts/min, and exercise duration was symptom-limited. Gas concentration and flow rate data were fed into a computer, which produced a real-time report on ventilatory and gas exchange parameters (breath-by-breath). The ventilatory parameters of .VE/.VCO2 slope and .VE/.VCO2 ratio computed at different times of the test were adopted.
  
  
  RESULTS
  Although there were no significant differences in .VE/.VCO2 ratio and .VE/.VCO2 slope when patients were grouped using the Los Andes clinical/hemodynamic classification, these parameters varied significantly when peak .VO2 was used to define patient groups.
  
  
  CONCLUSIONS
  Our results indicate that progressive deterioration in ventilatory response among chronic Chagas cardiopathy patients during exercise is more evident when the functional capacity (peak .VO2) is reduced, than when changes are related to the Los Andes classification.
authors.affiliation: Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rua das Laranjeiras 136/203, CEP 22240-000, Rio de Janeiro(RJ), Brazil. palha@ufrj.br
authors.forename: Fátima Palha de
authors.initials: FP
authors.lastname: Oliveira
authors.forename: Roberto Coury
authors.initials: RC
authors.lastname: Pedrosa
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology; D000704:Analysis of Variance; D016022:Case-Control Studies; D002598:Chagas Cardiomyopathy / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology*; D013997:Time Factors; D014463:Ultrasonography