[Modern cardiac pacing. II. Rate responsive pacemakers: clinical experience]

Rate responsive cardiac pacemakers adapting their pacing frequency according to physical effort are able to solve not only a bradycardia, but a chronotropic incompetence too. 23 rate responsive pulse generators, implanted in 1987-1991 in our center, simulated the physiological conditions and in this way they significantly improved both working capacity in bicycle stress test (p < 0.0001) and well-being in comparison with ordinary demand pacers. The incidence of complications did not exceed that in simple common pacemakers, but the rate adaptive ones were expensive and their programming was time consuming. In all three rate adaptive principles used their non-specific response revealed some imperfection of sensor driven devices. In addition, both in QT and in respiratory dependent systems their pretty proportional frequency response was delayed, while the irregular pacing rate in body activity sensor was not very proportionate to the physical exercise. The non-specific sensor response may be reduced by a combination of biologic sensors.