Abstract:
An extra-cardiovascular implantable cardioverter defibrillator (ICD) having a high voltage therapy module is configured to control a high voltage charging circuit to charge a capacitor to a pacing voltage amplitude to deliver charge balanced pacing pulses. The capacitor is chargeable to a shock voltage amplitude that is greater than the pacing voltage amplitude. The ICD is configured to enable switching circuitry of the high voltage therapy module to discharge the capacitor to deliver a first pulse having a first polarity and a leading voltage amplitude corresponding to the pacing voltage amplitude for pacing the patient's heart via a pacing electrode vector selected from extra-cardiovascular electrodes. The high voltage therapy module delivers a second pulse after the first pulse. The second pulse has a second polarity opposite the first polarity and balances the electrical charge delivered during the first pulse.
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. The dynamically shaped therapy stimulation waveforms facilitate achieving lower capture thresholds which reduces the device's supply consumption thereby increasing longevity of the device and facilitate a reduction of tissue damage.
Abstract:
An extra-cardiovascular implantable cardioverter defibrillator (ICD) having a high voltage therapy module is configured to control a high voltage charging circuit to charge a capacitor to a pacing voltage amplitude to deliver charge balanced pacing pulses. The capacitor is chargeable to a shock voltage amplitude that is greater than the pacing voltage amplitude. The ICD is configured to enable switching circuitry of the high voltage therapy module to discharge the capacitor to deliver a first pulse having a first polarity and a leading voltage amplitude corresponding to the pacing voltage amplitude for pacing the patient's heart via a pacing electrode vector selected from extra-cardiovascular electrodes. The high voltage therapy module delivers a second pulse after the first pulse. The second pulse has a second polarity opposite the first polarity and balances the electrical charge delivered during the first pulse.
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 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:
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:
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:
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 dual-transformer such that each cell is connected to only one of the transformers. Each transformer includes multiple windings and each of the 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:
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.