An implantable cardiac stimulation device provides bipolar pacing and
bipolar autocapture. If a measured bipolar electrode configuration
capture threshold is too high, an impedance measuring circuit measures
the impedance of the bipolar electrode configuration to determine a
possible lead failure. If the bipolar electrode configuration impedance
is within a normal range, bipolar pacing is continued in a manner which
assures continued capture of the heart. If the bipolar electrode
configuration impedance is outside of the given range of impedances, the
device is switched to unipolar pacing in a manner which insures capture
of the heart and notification of the need for a physician consultation.