Abstract: A medical device is configured to deliver a cardiac pacing pulse by enabling a bypass circuit to couple a cardiac pacing voltage source to a cardiac pacing output pathway that excludes a first portion of a high voltage output circuit used to deliver cardioversion/defibrillation shock pulses by the medical device and includes a second portion of the high voltage output circuit used for delivering cardioversion/defibrillation shock pulses.

Abstract: An implantable medical device includes a housing, a power source and an operational circuit that is coupled to the power source. The operational circuit includes a first electrode terminal and a second electrode terminal, an output circuit configured to deliver an electrical stimulation therapy through the first and second electrode terminals and a control circuit configured to evaluate an electrical parameter associated with the output circuit and to control generation of the electrical stimulation therapy responsive to a result of the evaluated parameter. Among other things, the implantable medical device may modify a parameter of the therapy delivery in response to a result of the evaluation.

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: An implantable medical device includes a low-power circuit, a high-power circuit, and a multi-cell power source. The implantable medical device delivers stimulation therapy to cardiac tissue. The cardioversion energy is delivered across through electrodes that are coupled to terminals of the high-power circuit. A protection circuit for protecting the low-voltage circuit components from high voltage pulses includes a first segment coupled to a first of the electrodes and a second segment coupled to a second of the electrodes, the components of the low-voltage circuit being coupled to the transthoracic protection circuit portion, and a reference potential corresponding to a ground potential, wherein the first and second segments of the transthoracic protection circuit portion are coupled to the reference potential in a parallel configuration.

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: An implantable medical device includes a housing, a power source and an operational circuit that is coupled to the power source. The operational circuit includes a first electrode terminal and a second electrode terminal, an output circuit configured to deliver an electrical stimulation therapy through the first and second electrode terminals and a control circuit configured to evaluate an electrical parameter associated with the output circuit and to control generation of the electrical stimulation therapy responsive to a result of the evaluated parameter. Among other things, the implantable medical device may modify a parameter of the therapy delivery in response to a result of the evaluation.

Abstract: An implantable medical device includes a low-power circuit, a high-power circuit, and a multi-cell power source. The implantable medical device delivers stimulation therapy to cardiac tissue. The cardioversion energy is delivered across through electrodes that are coupled to terminals of the high-power circuit. A protection circuit for protecting the low-voltage circuit components from high voltage pulses includes a first segment coupled to a first of the electrodes and a second segment coupled to a second of the electrodes, the components of the low-voltage circuit being coupled to the transthoracic protection circuit portion, and a reference potential corresponding to a ground potential, wherein the first and second segments of the transthoracic protection circuit portion are coupled to the reference potential in a parallel configuration.

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: 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: 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: 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 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: 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.