A system and method to deliver a therapeutic quantity of energy to a patient. The system includes a capacitor having a rated energy storage capacity substantially equal to the therapeutic quantity of energy, a boost converter coupled with the capacitor and constructed to release energy from the capacitor at a substantially constant current for a time interval, and an H-bridge circuit coupled with the boost converter and constructed to apply the substantially constant current in a biphasic voltage waveform to the patient. The method includes storing a quantity of energy substantially equal to the therapeutic quantity of energy in a capacitor, releasing the quantity of energy at a relatively constant current during a time interval using a boost converter coupled with the capacitor, and delivering a portion of the quantity energy in a direction to the patient using an H-bridge circuit coupled with the boost converter.

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 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.

A pulse generation system is disclosed. The pulse generation system includes a controller, an output terminal, and a plurality of pulse generator circuits. The controller is configured to cause a driving signal pulse to be transmitted to any selected one or more of the pulse generator circuits, and to cause the driving signal pulse to not be transmitted to any selected one or more other pulse generator circuits. Each of the pulse generator circuits is configured to generate an output voltage pulse at the output terminal in response to the driving signal pulse being transmitted thereto.

In one embodiment, a wearable cardioverter defibrillator (WCD) is described. The WCD includes a support structure worn by a patient. A processor is coupled to the support structure. The WCD also includes a discharge circuit coupled to an energy storage module, the discharge circuit configured to discharge the stored electrical charge through a body of the patient. The wearable cardioverter defibrillator also includes a user interface housing at least one sensor and responsive to changes in device orientation. The processor is configured to detect a motion at the user interface and determine when the motion is patient-activated. When the motion is patient-activated, the processor determines a direction of rotation. The processor determines an orientation of a display at the user interface based on the direction of rotation and orients the display at the user interface to appear upright to the patient.

A method of performing transthoracic defibrillation is described. The method includes generating at least two different defibrillation waveforms using at least two different defibrillation circuits contained in separate housings, delivering each of the at least two different defibrillation waveforms across a respective electrical path of a plurality of electrical paths established across the thoracic cavity and through the heart of a patient by at least three electrodes attached to the thorax of the patient, and synchronizing delivery of the at least two different defibrillation waveforms with communications between the separate housings.

A defibrillator disclosed in the present application including at least: a high voltage capacitor charged through a battery power source; a ladder bridge circuit connected to one end of the high voltage capacitor; a control unit for controlling an on/off operation of switching elements constituting the ladder bridge circuit, wherein the ladder bridge circuit comprises: a first circuit unit and a second circuit unit, one ends of which are connected to one end of the high voltage capacitor and which are connected in parallel to each other; and a third circuit unit connected in series to the other ends of the first circuit unit and the second circuit unit.

A novel therapeutic biphasic or multiphasic pulse waveform and method are provided. The novel therapeutic biphasic or multiphasic pulse waveform may be used in a defibrillator, or in another medical device that delivers therapeutic electrical stimulation pulses to a patient.

A dynamically adjustable multiphasic pulse system and method are provided. The dynamically adjustable multiphasic pulse system may be used as pulse system for a defibrillator or cardioverter.

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.