Dual chamber rate responsive pacing and chronotropic insufficiency: Comparison of an activity sensor respiratory sensor and a double sensor during exercise and during normal everyday activity

Late responsive DDD pacemakers are the most technically advanced devices pr esently available. These pacemakers are particularly useful in patients wit h chronotropic insufficiency when the sinus node is incapable of accelerati ng during exercise. The latest pacemakers have two sensors to reproduce opt imal physiological sinus acceleration. The aim of this study was to analyse the performances of a new rate respons ive pacemaker with a double activity and respiratory sensor, the interactio n of which is automatically controlled by a sophisticated algorithm, in 12 patients (8 men and 4 women) with a mean age of 75 +/- 7 years. Analysis wa s based on the performance of the sensors used singly or in association: -d uring three exercise stress tests with measurement of the VO2 max : - durin g everyday activities using the data archived by the pacemaker and the answ ers to a simplified questionnaire on quality of life. The results showed that during exercise stress testing with measurement of VO2 max, the best performances were obtained with the double sensor or the respiratory sensor compared with the activity sensor alone, suggesting that these two sensors are more effective in intense exercise. This tendency wa s also observed in the analysis of the memory bank of the pacemaker which s howed that the total duration of the faster heart rates was greater with th e two sensors. On the other hand, the quality of life was not significantly different, whichever sensor was studied. Longer scale trials are necessary to appreciate the real value of these new double sensor pacing devices and to identify the best indications for thei r usage.