IMPLANTABLE MEDICAL DEVICE FOR STIMULATING A HUMAN OR ANIMAL HEART

The invention relates to an implantable medical device for stimulating a human or animal heart, comprising a control unit, a memory unit, a stimulation unit for stimulating a cardiac region of a human or animal heart, and a detection unit for detecting an electrical signal of the same heart. The memory unit comprises a computer-readable program that causes the control unit to perform the following steps when executed on the control unit: a) detecting (110), with the detection unit, capture thresholds during an observation period, each capture threshold being detected in response to a sequence of pacing pulses delivered by the stimulation unit; b) storing the detected capture thresholds in the memory unit; c) determining (120) threshold-to-threshold differences between two consecutive capture thresholds in each case; and d) if a maximum determined threshold-to-threshold difference within the observation period is equal to or greater than a predetermined limit, adjusting (140; 170) a pacing output of the stimulation unit on the basis of the maximum capture threshold determined within a first time period, the first time period being equal to or shorter than the observation period; or if the maximum determined threshold-to-threshold difference within the observation period is smaller than the predetermined limit, adjusting (150; 170) the pacing output of the stimulation unit on the basis of the maximum capture threshold determined within a second time period, the second time period being shorter than the first time period.