Abstract: An implantable heart pacemaker includes a detector for natural heart muscle contractions in the region of the atrium and circuitry for stimulating heart muscle contractions in the region of the ventricle, the stimulating circuitry generating a stimulating pulse following the detection of a natural heart muscle contraction in the region of the atrium. The repetition rate of the pulses which stimulate heart muscle contractions in the region of the ventricle is limited to a maximum value which tracks and is not less than the heartbeat frequency adapted to the current physical activity of the pacemaker user.

Abstract: A medical device implantable into the body of a patient with which spontaneous tissue contractions can be detected and tissue contractions can be stimulated, generates a stimulation after the expiration of an adjustable first time interval, started by the respective detection or the stimulation of a tissue contraction, if a spontaneous tissue contraction is not detected before the expiration of the first time interval and if a shorter, second time interval, started by the detection or stimulation of a tissue contraction, has not yet expired. Detection of a spontaneous tissue contraction during the second time interval starts a new second time interval. The duration of the second time interval is automatically set such that it is always shorter by a defined amount than the duration of the first time interval.

Abstract: A method of finding rate responsive parameter settings in a functional relationship between sensor signal and stimulation frequency for a pacemaker by selecting desired heart rates optimal for a patient with respect to certain work loads. The respectively corresponding sensor signal values are obtained from the sensor, and the parameters are calculated by inserting the sensor signal values and selected frequencies into the functional relationship.

Abstract: An impedance measurement, used for controlling the pulse generation rate of the pacer, is obtained by placing an electrode in the ventricular portion, rather than the atrial portion, of the heart. The characteristic p-wave in the electrocardiogram is detected as a rapid inflection or notch in the impedance signal, with a stimulation pulse being generated with a time delay following detection of such a notch.