Patent US 4,884,576

It has been found from studies of healthy persons and patient's wearing pacemakers that the basic cardiovascular condition and the heart rate response to exercise varies considerably between different individuals. Thus, for effective control the individual differences must be taken into account. It would not be desirable to face the complexity of a pacemaker system that did not automatically adjust to these individual differences because there could not be knowledgeable persons in the field who could establish critical control conditions. This invention thus provides pacemaker methods for automatically establishing operating conditions for proper pacing rate control of a wide range of different individual conditions. Thus on line real time physiologically variable signals from the patient indicative of the patient's basic condition and suitable for pacing rate control are averaged over long and short term intervals and used to develop a pacing control signal. Typically the respiratory rate signal taken from a patient will provide information for adjusting the pacing rate to both the basic condition of the patient and the instanteous conditions encountered such as exercise.