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 external defibrillator system is configured with at least two different algorithms for determining the duration of a shock administered to a patient being treated and selects the algorithm based on one or more patient parameters such as, for example, the patient's TTI. The patient's TTI can be measured prior to or while the shock is being administered to the patient. The shock can be, for example, a multiphasic defibrillation or a multiphasic cardioversion shock. The charge voltage of the system's energy storage device can additionally be varied depending on the one or more patient parameters. For example, the system may charge the energy storage device so that the charge voltage is higher or lower than a nominal charge voltage responsive to the patient's TTI is higher or lower compared to an average TTI, respectively.

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 subcutaneously implantable device includes a housing, a clip attached to a top side of the housing that is configured to anchor the device to a bone, and an electrode that is configured to contact an organ. The clip includes a top portion that is rigid, a bottom portion that is rigid, and an intermediate portion between the top portion and the bottom portion that is configured to permit movement of the top portion with respect to the bottom portion and thereby apply force onto the bone between the top portion and the bottom portion.

Methods and systems are provided that comprise: sensing cardiac events of a heart; utilizing one or more processors to perform: declaring a ventricular fibrillation (VF) episode based on the cardiac events charging a single charge storage capacitor; delivering a multi-phase VF therapy that includes phase I and phase II therapies, wherein: a) during the phase I therapy, a combination of two or more medium voltage (MV) shocks are delivered entirely from the single charge storage capacitor; and b) during the phase II therapy, a low voltage pulse train is delivered at least partially from the single charge storage capacitor. Methods and systems are provided that comprise delivering first and second pulses of at least a first biphasic shock, wherein a parallel-series reconfiguration circuit connects and configures the capacitors of the capacitor bank in a parallel configuration to deliver a parallel biphasic shock; connecting the capacitors of the capacitor bank in a series configuration; and delivering first and second pulses of a second biphasic shock while the capacitors are connected in series to deliver a series biphasic shock.

A method, electrical tissue stimulation system, and programmer for providing therapy to a patient are provided. Electrodes are placed adjacent tissue (e.g., spinal cord tissue) of the patient, electrical stimulation energy is delivered from the electrodes to the tissue in accordance with a defined waveform, and a pulse shape of the defined waveform is modified, thereby changing the characteristics of the electrical stimulation energy delivered from the electrode(s) to the tissue. The pulse shape may be modified by selecting one of a plurality of different pulse shape types or by adjusting a time constant of the pulse shape.

A method for extinguishing a cardiac arrhythmia utilizes destructive interference of the passing of the reentry wave tip of an anatomical reentry through a depolarized region created by a relatively low voltage electric field in such a way as to effectively unpin the anatomical reentry. Preferably, the relatively low voltage electric field is defined by at least one unpinning shock(s) that are lower than an expected lower limit of vulnerability as established, for example, by a defibrillation threshold test. By understanding the physics of the electric field distribution between cardiac cells, the method permits the delivery of an electric field sufficient to unpin the core of the anatomical reentry, whether the precise or estimated location of the reentry is known or unknown and without the risk of inducting ventricular fibrillation. A number of embodiments for performing the method are disclosed.

A defibrillation system for synchronized cardioversion of a patient includes a first housing that includes a measurement circuit configured to receive electrocardiogram (ECG) signals and measure ECG parameters based on the ECG signals, and a first processor configured to analyze the ECG parameters, and initiate communication of a synchronization signal for a second processor for delivery of one or more defibrillation pulses and further includes a second housing that is separate from and external to the first housing and that includes a shock delivery circuit, and the second processor which is configured to receive the communication of the synchronization signal from the first processor, and control the shock delivery circuit to deliver the one or more defibrillation pulses in response to the synchronization signal.

Methods and apparatus for a three-stage atrial cardioversion therapy that treats atrial arrhythmias within pain tolerance thresholds of a patient. An implantable therapy generator adapted to generate and selectively deliver a three-stage atrial cardioversion therapy and at least two leads, each having at least one electrode adapted to be positioned proximate the atrium of the patient. The device is programmed for delivering a three-stage atrial cardioversion therapy via both a far-field configuration and a near-field configuration of the electrodes upon detection of an atrial arrhythmia. The three-stage atrial cardioversion therapy includes a first stage for unpinning of one or more singularities associated with an atrial 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 delivered via the near-field configuration of the electrodes.

A defibrillator produces a biphasic defibrillation pulse waveform with adjustable tilt for the second phase. The tilt of the second phase of the biphasic waveform can be controllably adjusted by selectively switching a current path which bypasses the patient during delivery of the second phase of the pulse. The inventive biphasic waveform can be delivered by a defibrillator with a single capacitance.