Abstract: An implantable medical device includes a low-power circuit, a high-power circuit, and a dual-cell power source. The power source is coupled to a transformer having first and second primary windings, each of which is selectively coupled to the power source and a plurality of secondary windings that are magnetically coupled to the first and second primary windings. The plurality of secondary windings are interlaced along a length of each of the secondary windings. Each of the plurality of secondary transformer windings is coupled to a capacitor, and the capacitors are all connected in a series configuration. The low power circuit is coupled to the power source and issues a control signal to control the delivery of charge from the power source to the plurality of capacitors through the first and second transformers.

Abstract: An implantable medical device includes a low-power circuit and a multi-cell power source. The cells of the power source are coupled in a parallel configuration. The implantable medical device includes both a low power circuit that is selectively coupled between the first and second cells and a high power output circuit that is directly coupled to the first and second cells in a parallel configuration. An isolation circuit is coupled to the first cell, the second cell and the low power circuit to maintain a current isolation between the first cell and the second cell at least during delivery currents having a large magnitude that are delivered to the high power output circuit.

Abstract: An implantable medical device includes a low-power circuit and a multi-cell power source. The cells of the power source are coupled to a transformer in a parallel configuration. The transformer includes multiple secondary windings and each of the windings is coupled to a capacitor that stores energy for delivery of a therapy to a patient. In accordance with embodiments of this disclosure, the low power circuit is configured to control simultaneous delivery of energy from each of the cells to a plurality of capacitors through the transformer.

Abstract: An implantable medical device includes a low-power circuit and a multi-cell power source. The cells of the power source are coupled in a parallel configuration. The implantable medical device includes both a low power circuit that is selectively coupled between the first and second cells and a high power output circuit that is directly coupled to the first and second cells in a parallel configuration. An isolation circuit is coupled to the first cell, the second cell and the low power circuit to maintain a current isolation between the first cell and the second cell at least during delivery of current having a large magnitude to the high power output circuit.

Abstract: Apparatus and methods for generating an induction waveform for performing threshold testing in an implantable medical device are disclosed. Such tests may be performed during the implant procedure, or during a device checkup procedure, or routinely during the lifetime of the device. The threshold test may include induction of an arrhythmia (such as ventricular fibrillation) followed by delivery of therapy at various progressively-increasing stimulation parameters to terminate the arrhythmia. As such, the capability to induce fibrillation within the device is desired. Induction of the arrhythmias may be accomplished via delivery of a relatively low energy shock or through delivery of an induction stimulation pulse to the cardiac tissue timed concurrently with the vulnerable period of the cardiac cycle.

Abstract: Techniques are disclosed for modulating the generation of charge current by operational circuitry included in an implantable medical device (IMD) for delivery of an induction stimulation pulse waveform by the IMD. The modulation may include modulating a charging circuit of the operational circuitry to facilitate the regulation of the induction stimulation pulse waveform. The techniques include monitoring an electrical parameter of a charging path during the delivery of the induction stimulation pulse and modulating the charging circuit based on the monitored electrical parameter.

Abstract: Recent advancements in power electronics technology have provided opportunities for enhancements to implantable medical device circuits. The enhancements have contributed to increasing circuit miniaturization and increased efficiency in the operation of the implantable medical devices. Stimulation therapy waveforms generated by the circuits include a stepped leading-edge that may be shaped having a varying slope and varying amplitudes associated with each of the segments of the slope. A charging circuit having a single primary transformer winding and a single secondary transformer winding that is coupled to a plurality of capacitors is utilized to generate the therapy stimulation waveforms. The stimulation waveform of the present disclosure may be dynamically shaped as a function of an individual patient's response.

Abstract: The disclosure describes circuits for providing therapy in an implantable medical device. The illustrative circuits include features that provide fault tolerance with graceful degradation as well as switching control methods that reduce component count and improves reliability.

Abstract: Recent advancements in power electronics technology have provided opportunities for enhancements to circuits of implantable medical devices. The enhancements have contributed to increasing circuit miniaturization and an increased efficiency in the operation of the implantable medical devices. The therapy delivery circuits and techniques of the disclosure facilitate generation of a therapy stimulation waveform that may be shaped based on the patient's physiological response to the stimulation waveform. The generated therapy stimulation waveforms include a stepped leading-edge that may be shaped having a varying slope and varying amplitudes associated with each of the segments of the slope. Unlike the truncated exponential waveform delivered by the conventional therapy delivery circuit which is based on the behavior of the output capacitors (i.e., i=C(dV/dt)), the stimulation waveform of the present disclosure may be dynamically shaped as a function of an individual patient's response.

Abstract: A subthreshold lead impedance technique is described for an implantable medical device. The lead impedance technique may be applicable to a subcutaneous implantable cardioversion defibrillator device and utilizes an output circuit of the device coupled between a first diode and a second diode to define a current path through two electrodes coupled to the output circuit. The second diode is further coupled to a switch to provide a current pathway from the first diode to circuit ground. A control circuit is coupled to the output circuit, the first diode, the second diode, and the switch to bias a leg of the output circuit in a conducting state while biasing the other legs of the output circuit in a non-conducting state.

Abstract: The disclosure relates to an apparatus and method for inducing ventricular fibrillation in a patient to facilitate defibrillation threshold testing. The apparatus includes a plurality of output capacitors that are dynamically configurable in a selected stacking arrangement that facilitates delivery of energy for inducing the ventricular fibrillation. An output of the apparatus is coupled to patient electrodes and a threshold energy level delivered by the output capacitors is determined.

Abstract: A subthreshold lead impedance technique is described for an implantable medical device. The lead impedance technique may be applicable to a subcutaneous implantable cardioversion defibrillator device and utilizes an output circuit of the device coupled between a first diode and a second diode to define a current path through two electrodes coupled to the output circuit. The second diode is further coupled to a switch to provide a current pathway from the first diode to circuit ground. A control circuit is coupled to the output circuit, the first diode, the second diode, and the switch to bias a leg of the output circuit in a conducting state while biasing the other legs of the output circuit in a non-conducting state.

Abstract: Recent advancements in power electronics technology have provided opportunities for enhancements to implantable medical device circuits. The enhancements have contributed to increasing circuit miniaturization and increased efficiency in the operation of the implantable medical devices. Stimulation therapy waveforms generated by the circuits include a stepped leading-edge that may be shaped having a varying slope and varying amplitudes associated with each of the segments of the slope. A charging circuit having a single primary transformer winding and a single secondary transformer winding that is coupled to a plurality of capacitors is utilized to generate the therapy stimulation waveforms. The stimulation waveform of the present disclosure may be dynamically shaped as a function of an individual patient's response.

Abstract: The disclosure relates to an apparatus and method for inducing ventricular fibrillation in a patient to facilitate defibrillation threshold testing. The apparatus includes a plurality of output capacitors that are dynamically configurable in a selected stacking arrangement that facilitates delivery of energy for inducing the ventricular fibrillation.

Abstract: Recent advancements in power electronics technology have provided opportunities for enhancements to circuits of implantable medical devices. The enhancements have contributed to increasing circuit miniaturization and an increased efficiency in the operation of the implantable medical devices. The therapy delivery circuits and techniques of the disclosure facilitate generation of a therapy stimulation waveform that may be shaped based on the patient's physiological response to the stimulation waveform. The generated therapy stimulation waveforms include a stepped leading-edge that may be shaped having a varying slope and varying amplitudes associated with each of the segments of the slope. Unlike the truncated exponential waveform delivered by the conventional therapy delivery circuit which is based on the behavior of the output capacitors (i.e., i=C(dV/dt)), the stimulation waveform of the present disclosure may be dynamically shaped as a function of an individual patient's response.

Abstract: This disclosure provides an implantable medical device comprising a power source a therapy module that includes at least one energy storage component, and a charging module coupled between the power source and the therapy module. The charging module is configured to control charging of the at least one energy storage component of the therapy module. The charging module may be further configured to detect a condition indicative of improper charging, to detect a condition indicative of the implantable medical device being subjected to fields generated by an magnetic resonance imaging (MRI) device, and to terminate charging of the at least one energy storage component when both the condition indicative of improper charging and the condition indicative of the implantable medical device being subjected to fields generated by the MRI device are detected.

Abstract: Techniques for controlling charging of a high voltage therapy energy storage component are provided to reduce any undesirable impact from charging during unusual operating conditions. Unusual operating conditions may be caused by any of a number of external factors, including saturation of charging transformer core, circuit failures, capacitor mismatches, or the like, which may result in an unexpected power supply voltage drop or abnormally high currents through device components. An implantable medical device may comprise a power source, a therapy module that includes at least one energy storage component, and a charging module coupled between the power source and the therapy module. The charging module is configured to obtain a measurement representative of an average power drawn from the power source and to terminate charging of the at least one energy storage component based at least on the measurement representative of an average power drawn from the power source.

Abstract: The disclosure describes circuits for providing therapy in an implantable medical device. The illustrative circuits include features that provide fault tolerance with graceful degradation as well as switching control methods that reduce component count and improves reliability.

Abstract: An implantable medical device is provided for isolating an elongated medical lead from internal device circuitry in the presence of a gradient magnetic or electrical field. The device includes an isolation circuit adapted to operatively connect an internal circuit to the medical lead in a first operative state and to electrically isolate the medical lead from the internal circuit in a second operative state.

Abstract: A power control circuit for an implantable medical device is presented. The power control circuit includes a first high rate cell, a second high rate cell, at least one resistive load, and at least one control circuit. The at least one resistive load is connected between the first and the second high rate cells. The at least one control circuit is coupled to the first and the second high rate cells.