Interindividual comparison of different sensor principles for rate adaptive pacing.

In recent years a multitude of rate adaptive sensor systems based on different sensor signals have been developed to adapt the pacing rate to the physical load of the patient. In contrast to those systems the closed loop stimulation (CLS) represents a new concept, which regards the pacemaker as part of the cardiocirculatory system. The pacemaker converts the regulating information of the circulatory center into a heart rate. This study compares the closed loop stimulation and the different sensor systems that evaluate external parameters for rate adaptive pacing with a control group. To this end, 27 patients and 15 patients with a healthy sinus node (control group) were subjected to physical and mental stress tests. The recorded results were analyzed with regard to the maximum rates reached during stress. The results show that none of the studied sensor-controlled systems was able to determine an adequate pacing rate under all of the various load states. The dual sensor systems experience problems in balancing the input of the two sensor signals when calculating the pacing rate. The evaluation of a single external parameter, such as the acceleration of the upper body with the accelerometer, also failed to provide an adequate pacing rate in many stress situations. In contrast to all sensor systems, CLS achieved a heart rate in agreement with those of the reference group in all physical and mental stress situations.