Implantable medical devices (IMDs) can perform a variety of diagnostic or therapeutic functions. In an example, an IMD can include one or more cardiac function management features, such as to monitor the heart or to provide electrical stimulation to a heart or to the nervous system, such as to diagnose or treat a subject, such as one or more electrical or mechanical abnormalities of the heart. Examples of IMDs can include pacers, automatic implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy (CRT) devices, implantable monitors, neuromodulation devices (e.g., deep brain stimulators, or other neural stimulators), cochlear implants, or drug pumps, among others.
Such IMDs can include electronic circuitry, such as to provide a desired electrostimulation, or to monitor physiologic activity. Such electronic circuitry can be coupled to an implantable lead assembly, such as including one or more electrodes or other electronic circuitry. A variety of different types of failures can affect systems including such IMDs and lead assemblies, such as including circuitry failures, electrical or mechanical coupling failures, or failure of a conductor or electrode included as a portion of a lead assembly attached to an IMD.
Germanson et al. (U.S. Pat. No. 7,515,961) mentions in vivo monitoring, detecting, and/or predicting potential failure modes or deleterious trends of chronically implanted medical electrical leads prior to actual failure of the leads, such as including using a relatively increased data sampling rate at various time intervals prior to actual detection of a deleterious trend.
Jorgenson et al. (U.S. Pat. Pub. No. 2002/0120307A1) mentions monitoring lead impedance, including collecting data from various sources in an implantable medical device system. Lead impedance, non-physiologic sensed events, percentage of time in mode switch, and results of capture management operation, sensed events, adversion pace counts, and refractory sense counts are used to determine a status of an implantable lead.