Patent ID: 7120493

Claim:
An implantable apparatus for treating cardiac arrhythmia, the apparatus comprising: a plurality of implantable leads including at least one high-energy shock lead, wherein the leads include at least one electrode, and wherein at least one lead and lead electrode is adapted and arranged to deliver high and low energy therapy to at least one region of the heart; an impedance measurement circuit coupled to the plurality of electrodes adaptable to measure the impedance between electrodes in a plurality of pairs of electrodes; a control circuit coupled to the impedance measurement circuit, wherein the controller circuit is adapted to initiate a impedance measurement between a pair of electrodes outside a high-energy electrical stimulus, wherein the control circuit sets a shorted lead indicator to a fault state when the impedance between a pair of electrodes is less than a predetermined value, and wherein the control circuit is adapted to prevent the same high-energy shock stimulus when the shorted lead indicator is set to a fault state.