Chronotropic incompetence in Chagas disease: effectiveness of blended sensor (volume/minute and accelerometer)

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.

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.

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).

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.

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.