Abstract: Methods and devices of cardiac electrode placement involve locating electrodes on a thorax of a patient. Surface pacing levels are determined relative to a pacing limit. Surface electrode locations are selected or rejected based on the level being within a limit. Electrodes may be relocated to new locations, and new surface pacing levels determined, until a new surface pacing level falls within the pacing limit. Selecting or rejecting electrode locations involves selecting locations suitable for implantation of subcutaneous cardiac electrodes and implanting at the selected locations.

Abstract: Methods and systems for defibrillation therapy involve delivering a pre-shock waveform to cause contraction of skeletal musculature in the patient's thorax before delivering a defibrillation waveform. A shock is delivered to the patient's heart during contraction of the skeletal musculature for a reduction in defibrillation threshold. The pre-shock waveform is sufficient in energy to cause one or both of deflation of the patient's lungs and muscle fiber shortening of the skeletal musculature. A delay interval may be initiated relative to delivery of the pre-shock waveform, wherein the defibrillation waveform is delivered following expiration of the delay interval. Motion of the patient's thorax and/or expiration of the patient's lungs may be detected, responsive to the pre-shock waveform. The defibrillation waveform may be delivered in coordination with the detected parameter, such as in relation to detection of a peak in the thoracic motion or minimum in transthoracic impedance.

Abstract: Systems and methods of verifying that implantable cardiac devices operate as intended in a particular patient involve one or more of determining proper placement of system components, determining stimulus levels useful for individual patient stratification, and determining stimulus levels that indicate efficacy of devices, implantable within a given patient. A pacing stimulus set at a surface pacing level is delivered to a patient's heart using surface electrodes. The patient is determined to not be a candidate for implantation of a subcutaneous defibrillation system if the surface pacing level needed to capture the heart exceeds a predetermined level. The patient may be determined to be a candidate for implantation of a subcutaneous system if the surface pacing level needed to effect capture is within an acceptance level. Such determinations are preferably based on a proportionality relationship between a subcutaneous defibrillation level and a surface pacing level.

Abstract: A system includes a housing with energy delivery circuitry and detection circuitry. One or more electrodes are coupled to the circuitry and used to sense cardiac and muscle activity. A processor is coupled to the energy delivery and detection circuitry. The processor may detect a ventricular arrhythmia using a cardiac signal developed from the sensed cardiac activity and may also detect an activity state of the patient using an activity signal developed from the sensed muscle activity. The processor modifies delivery of a therapy to treat the arrhythmia in response to the activity signal. A method involves detecting signals using subcutaneous electrodes, and discerning a cardiac signal and a patient activity signal from the detected signals. Arrhythmia therapy may be modified to treat the arrhythmia in response to the activity signal.

Abstract: Cardiac systems and methods using ECG and blood information for arrhythmia detection and discrimination. Detection circuitry is configured to produce an ECG. An implantable blood sensor configured to produce a blood sensor signal is coupled to a processor. The processor is coupled to the detection and energy delivery circuitry, and used to evaluate and treat cardiac rhythms using both the cardiac electrophysiologic and blood sensor signals. The blood sensor is configured for subcutaneous non-intrathoracic placement and provided in or on the housing, on a lead coupled to the housing, and/or separate to the housing and coupled to the processor via hardwire or wireless link. The blood sensor may be configured for optical sensing, using a blood oxygen saturation sensor or pulse oximeter. A cardiac rhythm may be evaluated using the electrocardiogram signal and the blood sensor signal, and tachyarrhythmias may be treated after confirmation using the blood sense signal.

Abstract: An implantable cardiac device includes first and second cans configured for subcutaneous, non-intrathoracic placement. Device circuitry is housed within and distributed between the first and second cans, including at least detection circuitry, energy delivery circuitry, and control circuitry. Communications circuitry may be included for communicating with a patient-external device. A lead may define a common potential and/or include a control line coupling the cans. Each of the first and second cans may include one or more sense and/or defibrillation electrodes. The cans may be coupled using only a wireless communications. Cardiac therapy may include bi-phasic or multi-phasic pulses concurrent, phased, and/or delayed between the two cans. Embodiments of methods in accordance with the present invention involve providing a first and second can of a cardiac therapy delivery device, each housing circuitry to deliver cardiac therapy concurrently, delayed and/or phased between the two cans.

Abstract: Systems and methods provide for sensing of cardiac activity from a subcutaneous, non-intrathoracic location, and detecting a cardiac condition necessitating treatment in response to the sensed cardiac activity. One of a number of cardiac therapies may be selectively delivered to treat the detected cardiac condition, such cardiac therapies including at least a tachycardia therapy, a bradycardia therapy, and an asystole prevention therapy.

Abstract: Subcutaneous tissue dissection tools, methods, systems, and kits incorporating transdermal illumination provide for enhanced navigation and depth determinations during subcutaneous tissue dissection. Subcutaneous dissection tools, methods, and systems provide access for deployment of subcutaneous electrodes, cans, and housings used in transthoracic defibrillation therapies, cardiac monitoring systems, transthoracic pacing therapies, or combinations of same. A dissection tool employing transdermal illumination includes a handle having a proximal end and a distal end. An elongated dissecting member extends from the distal end of the handle. A light source is provided within or to the dissection tool. The light source is adapted to provide a visible locating reference through the skin during subcutaneous tissue dissection.

Abstract: Transthoracic cardiac stimulation therapies provide for detection and treatment of cardiac asystole subsequent to delivery of a defibrillation therapy. A pacing therapy is transthoracicly delivered to terminate detected cardiac asystole using residual energy from a defibrillation energy storage source. The residual energy usable for the pacing therapy is sufficient to transthoracicly deliver at least one pacing pulse, and is typically sufficient to deliver a series of pacing pulses, prior to depletion of the defibrillation energy storage source. Detection of cardiac asystole is performed following delivery of each pacing pulse, and subcutaneous pacing support is terminated in response to detecting cardiac asystole termination.