Patent ID: 8688216

Claim:
An apparatus comprising: a therapy circuit configured to provide cardiac electrostimulation energy to a heart chamber of a subject using a set of implantable pacing electrodes; a cardiac signal sensing circuit configured to sense a cardiac activity signal; and a control circuit communicatively coupled to the cardiac signal sensing circuit and the therapy circuit, wherein the control circuit is configured to: initiate delivery of electrostimulation energy to the heart chamber according to a normal pacing mode; and initiate a first threshold test mode when receiving an indication to start a threshold test for the heart chamber and a sensing electrode independent from the set of pacing electrodes is unavailable for the heart chamber, wherein, when in the first threshold test mode, the control circuit is configured to recurrently change the electrostimulation energy delivered to the heart chamber, receive a cardiac activity signal sensed using a set of sensing electrodes that includes an electrode common to the set of pacing electrodes, and determine an optimum electrostimulation energy for capture of the heart chamber using the sensed cardiac activity signal.