Implantable Medical Device Having an Optimized Undersensing Management

Method for operating an implantable medical device implantable in a human or animal heart, the method comprising the following steps:

• a) continuously detecting a cardiac electric signal;
• b) starting a coagulation timer if the detected cardiac electric signal is indicative for an atrial tachycardia;
• c) keeping the coagulation timer active during a temporary loss of the cardiac electric signal;
• and
• d) stopping the coagulation timer, if the following criteria are fulfilled:
• i) an amplitude of the cardiac electric signal of a plurality of cardiac intervals being close in time exceeds a presettable significance threshold, and
• ii) an atrial rate calculated from the plurality of cardiac intervals being close in time is below a predefinable threshold rate indicative for atrial tachycardia, or
• e) keeping the coagulation timer active for a predefined time period, if the criteria are not fulfilled.

Method for treating an atrial tachycardia of a patient in need of such

• treatment, the method comprising the following steps:
• a) continuously detecting a cardiac electric signal;
• b) starting a coagulation timer if the detected cardiac electric signal is indicative for an atrial tachycardia;
• c) keeping the coagulation timer active during temporary loss of the cardiac electric signal;
• d) stopping the coagulation timer, if the following criteria are fulfilled:
• i) an amplitude of the cardiac electric signal of a plurality of cardiac intervals being close in time exceeds a presettable significance threshold, and
• ii) an atrial rate calculated from the plurality of cardiac intervals being close in time is below a predefinable threshold rate indicative for atrial tachycardia, or
• e) keeping the coagulation timer active for a predefined time period, if the criteria are not fulfilled;
• and
• f) applying an antitachycardic pacing only if the coagulation timer is active.