Dual-sensor-gesteuerte frequenzanpassung bei nicht-dynamischen belastungen: Wie physiologisch sind frequenzadaptive dual-sensor-schrittmacher wirklich?

Single sensor and dual sensor systems are used to reach physiological rate adaption in pacemaking therapy. The purpose of the present study was to examine the sensor-controlled heart rate reaction and adaptability of a dual sensor (QT + activity) with 3 different tests. Nine chronotropically incompetent patients (group 1), 3 females and 6 males, mean age 74.1±8.43 years, were implanted 5 VVIR and 4 DDDR pacemakers (Vitatron, The Netherlands). The control group included 10 chronotropically competent patients (group 2) (2 females, 8 males, mean age 58.2±12.6 years). Both groups underwent 3 diffenrent tests: 1) a mental test, 2) an isometric test and 3) an activity (=tap) test. Heart rate was measured every 30 seconds by the recorded surface ECG. We measured an unsatisfying heart rate response of the pacemaker patients in all 3 tests: During isometric exercise the pacing rate decreased from 63±3.5 bpm to 65±3.4 bpm (-0.97±0.71 bpm/min) (p=0.1829) in contrast to an increase of the heart rate in the control group: from 77.8±15.8 bpm to 92.5±19.9 bpm (3.76±1.29 bpm/min) (p=0.0048). During mental stress testing the pacing rate increased from 63±3.5 bpm to 65±3.4 bpm (0.66±0.20 bpm/min) (p=0.0199) in the pacemaker group from 75.8±15.8 bpm to 83.6±17.3 bpm (2.04±0.74 bpm/min) (p=0.0076). Tapping on the pacemaker case produced an increase of the pacing rate from 65.9±2.8 bpm to 73.6±3.8 bpm (2.83±0.73 bpm/min) (p=0.0004), whereas the heart rate decrased from 76.8±13.0 bpm/min to 75.0±1.9 bpm (-0.19±0.61 bpm/min) (p=0.7522) in the control group. Compared to the physiologically chronotropic function of the control group, the sensor-controlled heart rate response was inadequate during these tests. The expectations of sensor cross checking could not be fulfilled with the previous sensor combination (QT + activity).