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

Introduction

Technological progress of pacemakers has allowed the association of two or moresensors in one heart rate system response. The accelerometer sensor measures theintensity of the activity; it has a relatively rapid response to the beginning ofit, however, it may present insufficient response to less strenuous or of lessimpact exercise. The minute ventilation sensor changes the pacing rate in responseto changes in respiratory frequency in relation to tidal volume, allowingresponses to situations of emotional stress and low impact exercises.

Objective

To evaluate the cardiorespiratory response of the accelerometer with respect tothe blended sensor (BS=accelerometer sensor+minute ventilation sensor) to exercisein chagasic patients undergoing cardiopulmonary exercise test.

Methods

This was a prospective, observational, randomized, cross-sectional study. Patientswho met the inclusion criteria were selected. The maximum heart rate of the sensorwas programmed by age (220-age). The results were analyzed through t test withpaired 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% werefunctional class II, left ventricular ejection fraction was 58±7. As forthe cardiopulmonary test, maximum expected heart rate and VO2 were not achieved inboth the accelerometer sensor and the blended sensor, however, metabolicequivalent in the blended sensor was higher than the expected, all data withP<0.001.

Conclusion

Even though the maximal heart rate was not reached, the blended sensor provided aphysiological electrical sequence when compared to the accelerometer sensor,providing better physical fitness test in cardiopulmonary hemodynamics and greaterefficiency.