Abstract: Techniques are described for selectively enabling and disabling a pre-stimulation passive recharge pacing mode for an implantable medical device (IMD) depending on whether the IMD is operating in an electromagnetic interference (EMI)-safe mode. In some examples, the IMD may enable the pre-stimulation passive recharge pacing mode when the IMD is operating in the EMI-safe mode, and disable the pre-stimulation passive recharge pacing mode when the IMD is not operating in the EMI-safe mode. The EMI-safe mode may be, in some examples, a magnetic resonance imaging (MRI)-safe mode.

Abstract: An implantable medical system may include an implantable medical lead including at least one electrode and an implantable medical device. The implantable medical device comprises an electromagnetic interference (EMI) detection module that monitors for one or more particular characteristics of EMI. A control module is configured to control a therapy module to generate monophasic stimulation pulses while operating the IMD in a first operating mode. In response to detecting the condition indicative of the presence of EMI, the control module switches the IMD from the first operating mode to a second operating mode and generates at least one multiphasic stimulation pulses while operating the IMD in the second operating mode.

Abstract: An implantable medical system may include an implantable medical lead including at least one electrode and an implantable medical device. The implantable medical device comprises an electromagnetic interference (EMI) detection module that monitors for one or more particular characteristics of EMI. A control module is configured to control a therapy module to generate single stimulation pulses while operating the IMD in a first operating mode. In response to detecting the condition indicative of the presence of EMI, the control module switches the IMD from the first operating mode to a second operating mode and generates at least one group of two or more stimulation pulses in close proximity to one another in place of a single stimulation pulse while operating the IMD in the second operating mode.

Abstract: In general, this disclosure is directed to techniques and circuitry to determine characteristics of an implantable lead associated with an implantable medical device (IMD). The implantable lead may be designed to be MRI-safe by having one or more components that attenuate frequencies associated with an MRI that, if left unreduced, may interfere with the performance of the lead and/or cause harm to the tissue in which the lead is implanted. The circuitry may transmit a signal through the lead and receive a response signal. The device may determine the lead characteristics by comparing the transmitted signal with the received signal. In addition to determining whether the lead is MRI-safe, the techniques of this disclosure may be also utilized to determine whether the lead is faulty.

Abstract: Techniques are described for protecting an implantable medical device (IMD) from effects caused by interfering radiated fields. An IMD incorporating these techniques may include a telemetry conduction path that includes a first end electrically coupled to a telemetry antenna and a second end electrically coupled to a telemetry circuit disposed within a housing of the IMD. The IMD may further include a stub filter electrically coupled to the telemetry conduction path and configured to attenuate an interfering signal induced in the telemetry conduction path. The stub filter may include a dielectric and a conductor disposed within the dielectric. The conductor may include a first end electrically coupled to the telemetry conduction path and a second end configured in an open circuit configuration. The conductor may have an electrical length approximately equal to one-quarter wavelength of the interfering signal when propagating through the stub filter.

Abstract: An implantable medical device may include a telemetry module, a sensing module, a therapy delivery module, and a processor. The processor may be configured to detect a patient event based on data generated by the sensing module, operate the IMD in a first mode in which the telemetry module is disabled and the therapy delivery module is at least partially disabled when the patient event is not detected, and operate the IMD in a second mode in which the telemetry module is enabled and the therapy delivery module is at least partially disabled when the patient event is detected. In some examples, the processor is configured to, in the second mode, generate a notification of the cardiac arrhythmia and transmit the notification to an external device via the telemetry module. The external device may reside inside an MRI room or outside the MRI room, and may communicate with other devices.

Abstract: Techniques are described for controlling effects caused when an implantable medical device (IMD) is subject to a disruptive energy field. The IMD may include an implantable lead that includes one or more electrodes. The IMD may further include a first component having a parasitic inductance. The IMD may further include a second component having a reactance. In some examples, the reactance of the second component may be selected based on the parasitic inductance of the first component such that an amount of energy reflected along the lead in response to energy produced by an electromagnetic energy source is below a selected threshold. In additional examples, the parasitic inductance of the first component and the reactance of the second component are configured such that an amount of energy reflected along the lead in response to a frequency of electromagnetic energy is below a selected threshold.

Abstract: Techniques are described for controlling effects caused when an implantable medical device (IMD) is subject to a disruptive energy field. The IMD may include an implantable lead that includes one or more electrodes. The IMD may further include a first component having a parasitic inductance. The IMD may further include a second component having a reactance. In some examples, the reactance of the second component may be selected based on the parasitic inductance of the first component such that an amount of energy reflected along the lead in response to energy produced by an electromagnetic energy source is below a selected threshold. In additional examples, the parasitic inductance of the first component and the reactance of the second component are configured such that an amount of energy reflected along the lead in response to a frequency of electromagnetic energy is below a selected threshold.

Abstract: Apparatus and method according to the disclosure relate to promoting flow of body fluids in and around and between a substantially planar cardiac-sensing electrode and a shroud member utilizing spacing therebetween and/or one or more apertures, notches, slots and the like. For example, a relatively recessed area or aperture formed in an exemplary resin-based shroud member includes apertures that cooperate to promote flow of body fluids therearound.

Abstract: This disclosure describes techniques for reducing, and possibly eliminating, adverse effects caused by signals induced on an inductive antenna of an implanted medical device by varying magnetic fields from a source of interference, such as the gradient magnetic fields applied during an MRI procedure. For example, the implantable medical device includes an inductive antenna that receives signals via inductive coupling, a filter circuit that attenuates signals induced on the inductive antenna by varying magnetic fields generated from a source of interference and substantially passes signals induced on the inductive antenna by varying magnetic fields generated by an expected source and a telemetry module that processes the signals from the filter circuit.

Abstract: Per the disclosure subcutaneously implantable medical devices (IMDs) with rate responsive implantable pulse generator (IPG) capability that also include dual patient activity sensors are adaptively controlled. One of the activity sensors uses multiple electrodes adapted to acquire electrocardiographic signals and signals from non-cardiac muscle tissue (myopotentially-based signals). The signals from the electrode-based activity sensor are used to confirm and/or override the patient-activity sensor signals from the other non-myopotentially-based patient activity sensor. The electrodes are directly mechanically coupled to the housing of the IMD and electrically coupled to circuitry that filters, processes, and interprets both the patient activity sensor signals.

Abstract: Apparatus and method according to the disclosure relate to a mechanically and electrically coupling a plurality of electrodes to major opposing surface portions of an implantable medical device (IMD). The surface portions can comprise major opposing surfaces of a connector module of the IMD and/or substantially planar metallic surfaces of the IMD. The electrodes provide a subcutaneous cardiac activity sensing device via the plurality of electrodes which can be used in conjunction with one or more electrodes disposed in an insulative shroud coupled to the peripheral, minor surfaces of the IMD.

Abstract: Apparatus and method according to the disclosure relate to a substantially transparent shroud member and a substantially clear header portion adapted to mechanically and electrically couple to an implantable medical device (IMD). The assembly is used to provide a subcutaneous cardiac activity sensing device via at least a pair of electrodes mechanically coupled to the shroud member. The assemblies provided according to the disclosure allow complete visual inspection of all exterior components of an IMD, and for clamshell-type IMD housings provide increased hermeticity to the assembled device.

Abstract: The invention provides diverse ways to reduce if not eliminate the possibility of an errant electrical path from one or more conductors of the shroud to a portion of the conductive housing of its corresponding IMD. That is—as described hereinbelow prior to backfilling the shroud with medical adhesive as a final fabrication step—according to various forms of the invention biocompatible electrical insulation is added between an IMD housing and the elongated conductors that couple to the surface electrodes. For example, a parylene coating can be added to the outside of the IMD housing using a simple spraying procedure and/or dip coating the IMD housing into the parylene. Parylene is a proven biocompatible, electrically insulative material. In addition to or in lieu of a coating or layer of parylene, a dielectric layer such as titanium nitride (TiN) or the like can be sputtered to the elongated conductors.