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Abstract

A lead integrity measurement system for a cardiac pacemaker/cardioverter/defibrillator (PCD) of the type comprising an implantable pulse generator (IPG) and a lead system including one or more pacing leads each having a proximal end coupled to a pacing terminal of the IPG and a distal end with at least one pace/sense electrode in contact with a patient's heart and a pair of defibrillation leads coupled to defibrillation terminals of the IPG and defibrillation electrodes implanted in relation to the patient's heart. In a lead impedance test mode, the terminal of a selected defibrillation lead under test is coupled to system ground, and an excitation voltage is applied in an excitation path from a force lead terminal selected from the pacing leads. A measure lead is selected from among the other of the pacing leads and defibrillation leads, and the voltage induced in the lead under test is measured through the measure lead and the electrode/tissue interface of the measure lead and the defibrillation lead under test. The applied current in the excitation path is also measured, and an impedance value is derived from the measured current and voltage values. The test is continued with other selections of excitation and measure paths. Comparisons of the measured impedances with maximum and minimum impedance values are used to determine lead integrity failures. The lead impedance between two defibrillation leads is determined as a function of the sum of the derived defibrillation lead impedances.

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