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: 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 subcutaneous device includes a lead and electrode for cardiac monitoring and intervention. The device has an implantable lead including a lead body, a subcutaneous electrode supported by the lead body and a pharmacological agent impelled from the device using phoresis. The pharmacological agent provides a therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent and using phoresis to impel the pharmacological agent into subcutaneous non-intrathoracic tissue surrounding the lead.

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: Cardiac methods and devices that separate signals using at least two composite signals acquired at least at two input impedances. A target source impedance may be selected, and a cardiac signal may be separated from composite signals using the selected target source impedance. Medical systems include a cardiac device having a housing that provides amplification circuitry configured to have a first amplifier input impedance and a second amplifier input impedance, such as using two separate circuits or switching between two input impedances. One or more electrode assemblies are coupled to the amplification circuitry. A signal processor is provided in the housing configured to separate a source signal using a first composite signal detected at the first input impedance and a second composite signal detected at the second input impedance. The phase response of the first input amplifier circuit is about equal to that of the second input amplifier circuit.

Abstract: An implantable subcutaneous device and method employ a lead and an electrode for cardiac monitoring and intervention. The device includes an implantable lead having a lead body, a subcutaneous electrode coupled to the lead body, and a pharmacological agent provided on the implantable lead and/or electrode. The pharmacological agent provides a temporary therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent, and delivering the pharmacological agent to subcutaneous non-intrathoracic tissue surrounding the lead.

Abstract: Implementing a subcutaneous medical electrode system involves positioning a number of electrode subsystems in relation to a heart so that noise cancellation provides an improved signal to noise ratio of the cardiac signal and/or to provide one electrode arrangement preferential for cardiac signals and another arrangement preferential for noise signals. One of the electrode subsystems so positioned may include one or more can electrodes located on a housing enclosing a medical device. The medical device may be configured to provide therapeutic, diagnostic, or monitoring functions, including, for example, cardiac arrhythmia therapy.

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.

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: Subcutaneous systems and leads may be fixed in tissue after placement by use of one or more expanding fixation elements. An expanding fixation element is provided on an implantable lead and configured to secure one or both of a subcutaneous electrode and the lead body within subcutaneous non-intrathoracic tissue. A delivery apparatus comprising a sheath may be included that is configured to introduce the lead to a desired subcutaneous non-intrathoracic location within the patient. A method of lead delivery typically involves introducing a sheath into a subcutaneous non-intrathoracic body location of a patient, providing a lead comprising a lead body and an electrode, and advancing the lead through the sheath and to the subcutaneous non-intrathoracic body location. The method further involves fixing the lead to subcutaneous non-intrathoracic tissue using an expanding fixation element and thereafter removing the sheath from the patient.

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: 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: 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: An implantable subcutaneous device and method employ a lead and/or electrode for cardiac monitoring and intervention. The device includes an implantable lead having a lead body, a subcutaneous electrode supported by the lead body, and a pharmacological agent provided on the implantable lead body and/or an inactive can portion. The pharmacological agent provides a temporary therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent, and delivering the pharmacological agent to subcutaneous non-intrathoracic tissue surrounding the lead.

Abstract: An approach for implementing a subcutaneous medical electrode system involves positioning a number of electrode subsystems in relation to a heart so that a majority of ventricular tissue is included within a volume defined between the electrode subsystems. One of the electrode subsystems so positioned may include a can electrode located on a housing enclosing a medical device. The medical device may be configured to provide therapeutic, diagnostic, or monitoring functions, including, for example, cardiac arrhythmia therapy.

Abstract: Implementing a subcutaneous medical electrode system involves positioning a number of electrode subsystems in relation to a heart so that noise cancellation provides an improved signal to noise ratio of the cardiac signal and/or to provide one electrode arrangement preferential for cardiac signals and another arrangement preferential for noise signals. One of the electrode subsystems so positioned may include one or more can electrodes located on a housing enclosing a medical device. The medical device may be configured to provide therapeutic, diagnostic, or monitoring functions, including, for example, cardiac arrhythmia therapy.

Abstract: Implantable subcutaneous devices and methods incorporating a lead and/or electrode for cardiac monitoring and intervention, the lead employing chronic fixation elements including, for example, ridges, grooves, surface roughness, porosity, combined with acute fixation elements such as, for example, a suture site. A method of implanting subcutaneous leads may involve providing a lead comprising a lead body, an electrode, an acute fixation element, and one or more chronic fixation elements, and securing one or both of the lead body and the electrode to subcutaneous non-intrathoracic tissue at one or more fixation sites using the fixation elements. The method may involve: introducing a sheath into a subcutaneous non-intrathoracic body location of a patient; providing a lead comprising a lead body and an electrode; advancing the lead through the sheath and to the subcutaneous non-intrathoracic body location; fixing the lead to subcutaneous non-intrathoracic tissue; and removing the sheath from the patient.

Abstract: Subcutaneous systems and leads may be fixed in tissue after placement by use of one or more expanding fixation elements. An expanding fixation element is provided on an implantable lead and configured to secure one or both of a subcutaneous electrode and the lead body within subcutaneous non-intrathoracic tissue. A delivery apparatus comprising a sheath may be included that is configured to introduce the lead to a desired subcutaneous non-intrathoracic location within the patient. A method of lead delivery typically involves introducing a sheath into a subcutaneous non-intrathoracic body location of a patient, providing a lead comprising a lead body and an electrode, and advancing the lead through the sheath and to the subcutaneous non-intrathoracic body location. The method further involves fixing the lead to subcutaneous non-intrathoracic tissue using an expanding fixation element and thereafter removing the sheath from the patient.

Abstract: An implantable subcutaneous device includes a lead and electrode for cardiac monitoring and intervention. The device has an implantable lead including a lead body, a subcutaneous electrode supported by the lead body and a pharmacological agent impelled from the device using phoresis. The pharmacological agent provides a therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent and using phoresis to impel the pharmacological agent into subcutaneous non-intrathoracic tissue surrounding the lead.

Abstract: An implantable subcutaneous device and method employ a lead and an electrode for cardiac monitoring and intervention. The device includes an implantable lead having a lead body, a subcutaneous electrode coupled to the lead body, and a pharmacological agent provided on the implantable lead and/or electrode. The pharmacological agent provides a temporary therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent, and delivering the pharmacological agent to subcutaneous non-intrathoracic tissue surrounding the lead.