Rate-adaptive cardiac pacemaker

A rate-adaptive cardiac pacemaker comprising:

• a detection unit;
• an event-determining unit;
• a stimulation control unit;
• and
• a stimulation unit;
• wherein the event-determining unit is connected to the detection unit and the stimulation control unit, and the stimulation unit is connected to the stimulation control unit;
• wherein the detection unit is adapted to detect ECG signals of a heart;
• wherein the event-determining unit is adapted to determine whether a detected event represents a spontaneous or a stimulated event, on the basis of the ECG signals detected by the detection unit and the signals emitted by the stimulation control unit;
• and
• wherein the stimulation control unit is adapted to determine a stimulation rate depending upon a base rate and a physiological demand, and to vary the base rate at each detected natural or stimulated event based upon the determination of the event-determining unit;
• said stimulation control unit being in a first mode when atrial events occur in such a way that in the case of a spontaneous atrial event a spontaneous interval is prolonged by a first change value and that in the case of a stimulated atrial event a base interval is prolonged by a second change value, whereby in both cases the base rate is lowered, and
• said stimulation control unit being in a second mode when ventricular events occur to vary the base rate in such a way that in the case of a spontaneous ventricular event the base rate is raised by a third change value and in the case of a stimulated ventricular event the base rate is lowered by a fourth change value which is smaller than the third change value, and
• wherein the stimulation unit is adapted to stimulate the heart in accordance with the signals received from the stimulation control unit.