Patent ID: 7738959

Claim:
In a pacing system, wherein a pace pulse generator is selectively coupled to an active pace/sense electrode adapted to be placed in operative relation to a heart chamber and to one of an indifferent pace/sense electrode proximate to the active pace/sense electrode to deliver pace pulses to the heart chamber in a bipolar pace vector or a remote indifferent pace/sense electrode to deliver pace pulses to the heart chamber in a unipolar pace vector, and a sense amplifier coupled to the active pace/sense electrode and selectively coupled, to provide a prevailing sense vector, to one of the indifferent pace/sense electrode proximate to the active pace/sense electrode whereby the prevailing sense vector is a bipolar sense vector or to the remote indifferent pace/sense electrode whereby the prevailing sense vector is a unipolar sense vector, a method of periodically conducting a pacing threshold search in a pacing channel including the sense amplifier and the pace pulse generator coupled with the active and indifferent pace/sense electrodes, the pacing system including a predetermined value set for a high output pace pulse energy to be utilized when a high energy output pacing condition is detected, the method comprising: (a) triggering the commencement of the pacing threshold search; (b) conducting the pacing threshold search employing the sense amplifier sensing in the prevailing sense vector to determine if a stimulation energy threshold determined in the prevailing sense vector requires setting the pace pulse energy to the high output pace pulse energy to reliably capture the heart chamber; (c) if the high output pace pulse energy is determined to be required, selectively coupling the sense amplifier to an alternate one of the indifferent pace/sense electrodes to sense in the other one of the bipolar sense vector or unipolar sense vector as an alternate sense vector; (d) repeating step (b) to determine if the stimulation energy threshold determined in the alternate sense vector requires setting the pace pulse energy to a high output pace pulse energy to reliably capture the heart chamber; and (e) if the high output pace pulse energy is determined to be required in step (d), setting the prevailing sense vector to a default one of the bipolar or unipolar sense vectors and the pace pulse energy to the high output pace pulse energy and thereafter retriggering the pacing threshold search employing the default one of the vectors.