A wet electrolytic capacitor is provided. The capacitor contains an anode comprising an anodically oxidized pellet formed from a pressed and sintered powder, a cathode, and a working electrolyte in communication with the anode and the cathode. The working electrolyte is in the form of a gel and comprises an ammonium salt of an organic acid, inorganic oxide particles, a gelation activator, an acid, and a solvent system that comprises water. The working electrolyte has a pH value of from about 5.0 to about 8.0.

Improved devices, circuits and methods of operation in implantable stimulus systems. An implantable defibrillator may comprise an H-bridge output circuit having low and high sides, with a current controlling circuit coupled to the high side of the H-bridge output circuit and a current monitoring circuit coupled to the low side of the H-bridge output circuit. Alternate current paths to the output of the H-bridge, or to the H-Bridge itself, are used for delivering different therapies to the patient.

Automated External Defibrillator (AED) devices may include a high voltage capacitor (HV Cap) configured to store energy required to deliver a defibrillation shock to a patient; batteries configured to charge the HV Cap; a DC/DC converter circuit including a high voltage transformer, a FET switch with associated driver, and a rectifying diode; an H-bridge circuit configured to transform energy released from the HV Cap into a bi-phasic pulse; and a memory and microprocessor configured to operate the AED device. In particular, the HV Cap, the DC/DC converter circuit, the H-bridge circuit, the one or more batteries, and the memory and the microprocessor may contained in a pocket-sized housing, the AED device may be configured to continuously monitor and adjust the rate at which the batteries charge the HV Cap, and the AED device may include a variable frequency relaxation oscillator circuit configured to acquire a patients Z-body measurement.

In embodiments, an external defibrillator has an electrical circuit with a special output stage for the high-voltage defibrillation pulse. The output stage includes switches that can turn on for delivering the pulse, and off during all other times. The output stage also includes a diverting resistance to divert electrical current that could leak into the patient while a capacitor is being charged. An optional detector may notify if a component is malfunctioning. An advantage can be that an external defibrillator may be created according to embodiments that uses, in its output stage, semiconductor switches instead of relays. As semiconductor switches weigh less and occupy less volume than relays, an external defibrillator according to embodiments may have less weight and volume. Especially in wearable defibrillator applications, less weight means less effort to carry and less volume means easier concealment under clothing.

Methods and apparatus for a three-stage ventricular cardioversion and defibrillation therapy that treats ventricular tachycardia and fibrillation at low energy levels. An implantable therapy generator adapted to generate and selectively deliver a three-stage ventricular therapy and at least two leads operably each having at least one electrode adapted to be positioned proximate the ventricle of the patient. The device is programmed to deliver a three-stage therapy via both a far-field configuration and a near-field configuration of the electrodes upon detection of a ventricular arrhythmia. The three-stage therapy includes a first stage for unpinning of one or more singularities associated with the ventricular arrhythmia, a second stage for anti-repinning of the one or more singularities, both of which are delivered via the far-field configuration of the electrodes, and a third stage for extinguishing of the one or more singularities associated delivered via the near-field configuration of the electrodes.

A patient-worn arrhythmia monitoring and treatment device includes a pair of therapy electrodes and at least one pair of sensing electrodes disposed proximate to the skin and configured to continually sense at least one ECG signal of the patient over an extended period of time. The device includes a therapy delivery circuit coupled to the pair of therapy electrodes and configured to deliver one or more therapeutic pulses. A controller coupled to therapy delivery circuit is configured to analyze the at least one ECG signal and detect one or more treatable arrhythmias and cause the therapy delivery circuit to deliver the one or more therapeutic pulses to the patient. At least one of the one or more therapeutic pulses is formed as a biphasic waveform delivering within 15 percent of 360 J of energy to a patient body having a transthoracic impedance from about 20 to about 200 ohms.

A medical device that includes a power source, a therapy delivery interface, therapy electrodes, electrocardiogram (ECG) sensing electrodes to sense ECG signal of a heart of a patient, a sensor interface to receive and digitize the ECG signal, and a processor. The processor is configured to analyze the ECG signal to determine a cardiac rhythm and a transform value representing a magnitude of a frequency component of the cardiac rhythm, analyze the cardiac rhythm and the transform value to detect a shockable cardiac arrhythmia by classifying the cardiac rhythm as a noise rhythm or a shockable cardiac arrhythmia rhythm based on the transform value, and causing the processor to detect the cardiac arrhythmia if classifying the cardiac rhythm as a shockable cardiac arrhythmia rhythm, initiate a treatment alarm sequence, adjust the shock delivery parameter for a defibrillation shock, and provide the defibrillation shock via the therapy electrodes.

Methods and apparatus for a three-stage ventricular cardioversion and defibrillation therapy that treats ventricular tachycardia and fibrillation at low energy levels. An implantable therapy generator adapted to generate and selectively deliver a three-stage ventricular therapy and at least two leads operably each having at least one electrode adapted to be positioned proximate the ventricle of the patient. The device is programmed to deliver a three-stage therapy via both a far-field configuration and a near-field configuration of the electrodes upon detection of a ventricular arrhythmia. The three-stage therapy includes a first stage for unpinning of one or more singularities associated with the ventricular arrhythmia, a second stage for anti-repinning of the one or more singularities, both of which are delivered via the far-field configuration of the electrodes, and a third stage for extinguishing of the one or more singularities associated delivered via the near-field configuration of the electrodes.

An extra-cardiovascular implantable cardioverter defibrillator (ICD) is configured to induce a tachyarrhythmia by charging a high voltage capacitor to a voltage amplitude and delivering a series of pulses to a patient's heart by discharging the capacitor via an extra-cardiovascular electrode vector. Delivering the series of pulses includes recharging the high-voltage capacitor during an inter-pulse interval between consecutive pulses of the series of pulses.

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.