Patent ID: 7532930

Claim:
An implantable electrostimulator for the stimulation of a heart, in particular for at least two heart chambers, said electrostimulator comprising: at least one atrial and ventricular channel; electrode connections which are connected to a stimulation unit for the delivery of atrial and ventricular stimulation pulses, in such a way that atrial or ventricular stimulation pulses are to be delivered by way of one or more electrode lines connected to the electrode connections; a stimulation control unit which is connected to the stimulation unit and which is adapted to trigger the delivery of stimulation pulses and to determine the strength of the stimulation pulses and for that purpose to deliver a stimulation control signal to the stimulation unit; and a detection unit which is connected to the stimulation control unit and at least indirectly to the electrode connections and which is adapted to evaluate electrical potentials which are applied to the electrical connections and which in particular are to be intracardially recorded in order to detect intrinsic atrial events characteristic of natural contractions of an atrium, and wherein the stimulation control unit is adapted for the purposes of stimulation success checking (capture detection) in the atrium to trigger at least one atrial stimulation pulse and to detect stimulation success (capture) in the atrium or ineffective atrial stimulation (non-capture) on the basis of non-detection or detection respectively of at least one possibly occurring intrinsic (natural, spontaneous) atrial event within a predetermined period of time, and at least for a limited period of time serving in particular for stimulation success checking (capture detection) or a stimulus threshold test, to trigger ventricular stimulation pulses with the expiry of an AV interval which begins with an intrinsic or stimulated atrial event and which is so short that fusion events, that is to say events in respect of which a ventricular stimulation pulse occurs substantially at the same time as a natural ventricular contraction, are avoided, by setting the AV interval for said limited period of time to a value that is shorter than an AV interval corresponding to an intrinsic rate (SR) prior to said limited period of time or shorter than an AV interval corresponding to the stimulation rate (PR) prior to said predetermined period of time, whichever is shorter, and to distinguish atrial events which are based on far-field detection of ventricular events in the atrium from intrinsic atrial events insofar as such atrial events which are at a spacing in respect of time with respect to the respectively preceding ventricular stimulation pulse, which at least approximately corresponds to the time spacing between a ventricular stimulation pulse and the corresponding atrial event in a preceding or later cardiac cycle, are evaluated as based on far-field detection and are not counted as intrinsic events.