Abstract: A medical device and associated method record signals from each real axis of a multi-axis sensor. An optimal axis for monitoring a physiological signal of the patient is identified from the real axes of the multi-axis sensor and multiple virtual axes. Coordinates defining the optimal axis are stored as respective weighting factors of the signals from each real axis of the multi-axis sensor. A metric of the physiological signal is determined using the multi-axis sensor signals and the weighting factors.

Abstract: An extra-cardiovascular implantable cardioverter defibrillator (ICD) having a low voltage therapy module and a high voltage therapy module is configured to select, by a control module of the ICD, a pacing output configuration from at least a low-voltage pacing output configuration of the low voltage therapy module and a high-voltage pacing output configuration of the high voltage therapy module. The high voltage therapy module includes a high voltage capacitor having a first capacitance and the low voltage therapy module includes a plurality of low voltage capacitors each having up to a second capacitance that is less than the first capacitance. The ICD control module controls a respective one of the low voltage therapy module or the high voltage therapy module to deliver extra-cardiovascular pacing pulses in the selected pacing output configuration via extra-cardiovascular electrodes coupled to the ICD.

Abstract: An implantable medical device is configured to control a therapy module to couple a capacitor array comprising a plurality of capacitors to a plurality of extra-cardiovascular electrodes and control the therapy module to deliver a composite pacing pulse to a patient's heart via the plurality of extra-cardiovascular electrodes by sequentially discharging at least a portion of the plurality capacitors to produce a series of at least two individual pulses that define the composite pacing pulse.

Abstract: This disclosure is directed to techniques for delivering cardiac pacing pulses to a patient's heart by a cardiac system, such as an extra-cardiovascular ICD system. An ICD operating according to the techniques disclosed herein delivers cardiac pacing pulses using high-voltage therapy circuitry typically configured for delivering high-voltage cardioversion/defibrillation shocks. The ICD delivers the high-voltage pacing therapy via extra-cardiovascular electrodes, such as one or more extra-cardiovascular electrodes carried by a medical electrical lead extending from the ICD and/or the housing of the ICD.

Abstract: 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.

Abstract: This disclosure provides an extravascular ICD system and method for defibrillating a heart of a patient. The extravascular ICD system includes multiple extravascular electrical stimulation leads or lead segments located in close proximity to one another and having respective defibrillation electrodes. The ICD system utilizes the multiple defibrillation electrodes to form an extravascular electrode vector that may result a reduction in the shock impedance and/or a reduction in the DFT compared to extravascular ICD systems that include only a single extravascular defibrillation electrode. An ICD of the system may, for example, deliver a defibrillation shock using an electrode vector in which a first polarity of the electrode vector is formed by electrically coupling first and second defibrillation electrodes of first and second leads, respectively, to the therapy circuitry and a second polarity of the electrode vector is formed by electrically coupling a housing of the ICD to the therapy circuitry.

Abstract: An implantable medical electrical lead having an elongate lead body having a proximal end and a distal portion. A plurality of defibrillation electrodes coupled to the distal portion is included, the plurality of electrodes being transitionable from a first configuration in which the defibrillation electrodes are biased in an expanded configuration to a second configuration in which the defibrillation electrodes are in a collapsed configuration.

Abstract: This disclosure describes an implantable medical electrical lead and an ICD system utilizing the lead. The lead includes a lead body defining a proximal end and a distal portion, wherein at least a part of the distal portion of the lead body defines an undulating configuration. The lead includes a defibrillation electrode that includes a plurality of defibrillation electrode segments disposed along the undulating configuration spaced apart from one another by a distance. The lead also includes at least one electrode disposed between adjacent sections of the plurality of defibrillation sections. The at least one electrode is configured to deliver a pacing pulse to the heart and/or sense cardiac electrical activity of the heart.

Abstract: This disclosure provides an extravascular ICD system and method for defibrillating a heart of a patient. The extravascular ICD system includes multiple extravascular electrical stimulation leads or lead segments located in close proximity to one another and having respective defibrillation electrodes. The ICD system utilizes the multiple defibrillation electrodes to form an extravascular electrode vector that may result a reduction in the shock impedance and/or a reduction in the DFT compared to extravascular ICD systems that include only a single extravascular defibrillation electrode. An ICD of the system may, for example, deliver a defibrillation shock using an electrode vector in which a first polarity of the electrode vector is formed by electrically coupling first and second defibrillation electrodes of first and second leads, respectively, to the therapy circuitry and a second polarity of the electrode vector is formed by electrically coupling a housing of the ICD to the therapy circuitry.

Abstract: Implantable medical electrical leads having electrodes arranged such that a defibrillation coil electrode and a pace/sense electrode(s) are concurrently positioned substantially over the ventricle when implanted are described. The leads include an elongated lead body having a distal portion and a proximal end, a connector at the proximal end of the lead body, a defibrillation electrode located along the distal portion of the lead body, wherein the defibrillation electrode includes a first segment and a second segment proximal to the first segment by a distance, a first electrical conductor extending from the proximal end of the lead body and electrically coupling to the first segment and the second segment of the defibrillation electrode, and at least one pace/sense electrode located between the first segment and the second segment of the defibrillation electrode.

Abstract: In situations in which an implantable medical device (e.g., a subcutaneous ICD) is co-implanted with a leadless pacing device (LPD), it may be important that the subcutaneous ICD knows when the LPD is delivering pacing, such as anti-tachycardia pacing (ATP). Techniques are described herein for detecting, with the ICD and based on the sensed electrical signal, pacing pulses and adjusting operation to account for the detected pulses, e.g., blanking the sensed electrical signal or modifying a tachyarrhythmia detection algorithm. In one example, the ICD includes a first pace pulse detector configured to obtain a sensed electrical signal and analyze the sensed electrical signal to detect a first type of pulses having a first set of characteristics and a second pace pulse detector configured to obtain the sensed electrical signal and analyze the sensed electrical signal to detect a second type of pulses having a second set of characteristics.

Abstract: Implantable medical electrical leads having electrodes arranged such that a defibrillation coil electrode and a pace/sense electrode(s) are concurrently positioned substantially over the ventricle when implanted as described. The leads include an elongated lead body having a distal portion and a proximal end, a connector at the proximal end of the lead body, a defibrillation electrode located along the distal portion of the lead body, wherein the defibrillation electrode includes a first electrode segment and a second electrode segment proximal to the first electrode segment by a distance. The leads may include at least one pace/sense electrode, which in some instances, is located between the first defibrillation electrode segment and the second defibrillation electrode segment.

Abstract: In situations in which an implantable medical device (IMD) (e.g., an extravascular ICD) is co-implanted with a leadless pacing device (LPD), it may be important that the IMD knows when the LPD is delivering pacing, such as anti-tachycardia pacing (ATP). Techniques are described herein for detecting, with the IMD and based on the sensed electrical signal, pacing pulses and adjusting operation to account for the detected pulses, e.g., blanking the sensed electrical signal or modifying a tachyarrhythmia detection algorithm. In one example, the IMD includes a pace pulse detector that detects, based on the processing of sensed electrical signals, delivery of a pacing pulse from a second implantable medical device and blank, based on the detection of the pacing pulse, the sensed electrical signal to remove the pacing pulse from the sensed electrical signal.

Abstract: A medical device and associated method record signals from each real axis of a multi-axis sensor. An optimal axis for monitoring a physiological signal of the patient is identified from the real axes of the multi-axis sensor and multiple virtual axes. Coordinates defining the optimal axis are stored as respective weighting factors of the signals from each real axis of the multi-axis sensor. A metric of the physiological signal is determined using the multi-axis sensor signals and the weighting factors.

Abstract: A medical device system for advancing a subcutaneous device to a desired implant site that includes a strap extending along a length from a proximal end to a distal end, a first flange and a second flange extending along a portion of the length of the strap, a base portion extending along a portion of the length of the strap between the first flange and the second flange, and an indentation extending from the proximal end to the distal end of the strap, the indentation formed by the first flange, the second flange, and the base portion, wherein the first flange and the second flange include curved bottom portions that make contact with and compress a tissue layer to position the tissue layer within the indentation during the placement of the subcutaneous device.

Abstract: A guiding accessory, for use in conjunction with a guidewire and a catheter of an implant system, facilitates passage of an elongate and flexible conductor of a relatively compact therapy delivery device to an implant site, for example, within the cardiac venous system, when a therapy generator of the device is held within a distal portion of the catheter, and the catheter, device and guiding accessory are advanced along the guidewire. The guiding accessory includes a helically extending wall that forms a lumen within which the device conductor and guidewire extend. After advancing the catheter, guiding accessory and device to the implant site, the helically extending wall is unwound from around the device conductor, for removal, preferably, by pulling proximally on a tension line, which is attached to a proximal end of the wall.

Abstract: 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.

Abstract: An apparatus and method for delivering an external shock pulse receive pacing pulses generated by a first device and a shock pulse generated by a second device. An output of the apparatus is coupled to patient electrodes and the apparatus controls delivery of the received pacing pulses to the output and delivery of the received shock pulse to the output. A control module, pacing control and shock control included in the apparatus cooperatively control delivery of the received shock pulse to the output at a predetermined delay after one of the received pacing pulses.

Abstract: A guiding accessory, for use in conjunction with a guidewire and a catheter of an implant system, facilitates passage of an elongate and flexible conductor of a relatively compact therapy delivery device to an implant site, for example, within the cardiac venous system, when a therapy generator of the device is held within a distal portion of the catheter, and the catheter, device and guiding accessory are advanced along the guidewire. The guiding accessory includes a helically extending wall that forms a lumen within which the device conductor and guidewire extend. After advancing the catheter, guiding accessory and device to the implant site, the helically extending wall is unwound from around the device conductor, for removal, preferably, by pulling proximally on a tension line, which is attached to a proximal end of the wall.

Abstract: 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.