title: Chronotropic incompetence in Chagas disease: effectiveness of blended sensor (volume/minute and accelerometer).
abstract: BACKGROUND
  Technological progress of pacemakers has allowed the association of two or more sensors in one heart rate system response. The accelerometer sensor measures the intensity of the activity; it has a relatively rapid response to the beginning of it, however, it may present insufficient response to less strenuous or of less impact exercise. The minute ventilation sensor changes the pacing rate in response to changes in respiratory frequency in relation to tidal volume, allowing responses to situations of emotional stress and low impact exercises.
  
  
  OBJECTIVE
  To evaluate the cardiorespiratory response of the accelerometer with respect to the blended sensor (BS=accelerometer sensor+minute ventilation sensor) to exercise in chagasic patients undergoing cardiopulmonary exercise test.
  
  
  METHODS
  This was a prospective, observational, randomized, cross-sectional study. Patients who met the inclusion criteria were selected. The maximum heart rate of the sensor was programmed by age (220-age). The results were analyzed through t test with paired samples (P<0.05).
  
  
  RESULTS
  Sample was comprised of 44 patients, with a mean age of 66±10.4 years, 58% were female, 54% as first implant, in 74% were functional class I and 26% were functional class II, left ventricular ejection fraction was 58±7. As for the cardiopulmonary test, maximum expected heart rate and VO2 were not achieved in both the accelerometer sensor and the blended sensor, however, metabolic equivalent in the blended sensor was higher than the expected, all data with P<0.001.
  
  
  CONCLUSIONS
  Even though the maximal heart rate was not reached, the blended sensor provided a physiological electrical sequence when compared to the accelerometer sensor, providing better physical fitness test in cardiopulmonary hemodynamics and greater efficiency.
authors: Pontifícia Universidade Católica de Goiás, Goiânia, GO, BR.
authors: Antonio da Silva
authors: Ada S
authors: Menezes Junior
authors: Pontifícia Universidade Católica de Goiás, Goiânia, GO, BR.
authors: Aline Pereira da
authors: AP
authors: Silva
authors: Pontifícia Universidade Católica de Goiás, Goiânia, GO, BR.
authors: Giovana Gurian Batista
authors: GG
authors: Profahl
authors: Pontifícia Universidade Católica de Goiás, Goiânia, GO, BR.
authors: Catarine
authors: C
authors: Ottobeli
authors: Pontifícia Universidade Católica de Goiás, Goiânia, GO, BR.
authors: Jutay Fernando Silva
authors: JF
authors: Louzeiro
mesh_terms: D061725:Accelerometry / Q000295:instrumentation; D000368:Aged; D002304:Cardiac Pacing, Artificial; D014355:Chagas Disease / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D011897:Random Allocation; D012016:Reference Values; D056152:Respiratory Rate / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology; D013997:Time Factors