Abstract: Active surveillance of potential lead anomalies in implanted medical leads utilizes test signal(s) delivered through an output current pathway and induced signals monitored via an independent monitor current pathway to detect for any reactions to the test signals in the induced signals. Various specific responses can be initiated if a potential insulation breach or anomaly in the implanted medical lead is identified due to detection of a “positive” test result in the induced signals on the monitor current pathway in reaction to a test signal applied to the output current pathway.

Abstract: A method and system for the diagnosis of anomalies in a lead attached to an implantable medical device, such as an implantable cardioverter defibrillator (ICD), including an insulation breach resulting in a short circuit of the high-voltage shock pulse. Determination that the defibrillation pathway is shorted may be made by initial analysis of a Reference EGM and Diagnostic EGM and subsequent analysis of Differential Diagnostic EGMs. Upon determining if a specific defibrillation pathway is shorted, the nonessential defibrillation electrode of that pathway may be excluded from the defibrillation circuit, delivering defibrillation current only between functioning defibrillation electrodes. Alternatively, the ICD system can confirm the presence of a lead anomaly with one or more alternative diagnostic approaches. Patient and remote-monitoring alerts may be initiated.

Abstract: A method and apparatus to detect anomalies in the conductors of leads attached to implantable medical devices based on the dynamical electrical changes these anomalies cause. In one embodiment, impedance is measured for weak input signals of different applied frequencies, and a conductor anomaly is detected based on differences in impedance measured at different frequencies. In another embodiment, a transient input signal is applied to the conductor, and an anomaly is identified based on parameters related to the time course of the voltage or current response, which is altered by anomaly-related changes in capacitance and inductance, even if resistance is unchanged. The method may be implemented in the implantable medical device or in a programmer used for testing leads.

Abstract: Disclosed is a method for the diagnosis of conductor anomalies, such as an insulation failure resulting in a short circuit, in an implantable medical device, such as an implantable cardioverter defibrillator (ICD). Upon determining if a specific defibrillation pathway is shorted, the method excludes the one electrode from the defibrillation circuit, delivering defibrillation current only between functioning defibrillation electrodes. Protection can be provided against a short in the right-ventricular coil-CAN defibrillation pathway of a pectoral, transvenous ICD with a dual-coil defibrillation lead. If a short caused by an in-pocket abrasion is present, the CAN is excluded from the defibrillation circuit, delivering defibrillation current only between the right-ventricular and superior vena cava defibrillation coils. Determination that the defibrillation pathway is shorted may be made by conventional low current measurements or delivery of high current extremely short test pulses.

Abstract: Methods and apparatus for accurately and painlessly measuring the impedance between defibrillation electrodes implanted in a patient utilize a high current test pulse delivered with a sufficiently high current to produce an accurate measurement of the defibrillation electrode impedance while limiting the duration of the test pulse such that the pain sensing cells in the patient do not perceive the test pulse. In one embodiment, the test pulse is generated from the high voltage transformer without storing energy in the high voltage capacitors and is delivered to the defibrillation electrodes in the patient utilizing the high voltage switching circuitry.