A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.

An implantable medical device comprising a signal generator configured to generate and deliver anti-tachyarrhythmia pacing (ATP) to a heart of a patient and processing circuitry. The processing circuitry is configured to detect an enable event, responsive to detecting the enable event, enable the delivery of ATP by the signal generator, detect a disable event indicating that another implantable medical device cannot be relied upon to deliver an anti-tachyarrhythmia shock, and responsive to detecting the disable event, disable delivery of ATP.

Techniques are disclosed for determining, by an extracardiovascular implantable cardioverter defibrillator (ICD) implanted in a patient, whether one or more test therapy signals generated by another medical device implanted in the patient is detected. In response to detecting the one or more test therapy signals, the extracardiovascular ICD provides an indication that the extracardiovascular ICD has detected the one or more test therapy signals. In some examples, the indication is an audible tone provided to a clinician. In some examples, the other medical device is an intracardiac cardiac pacing device, and the one or more test therapy signals comprises a plurality of anti-tachycardia pacing (ATP) pulses.

An ICD multimode system comprises a microcontroller or FPGA having a memory, a differentially driven phased array amplifier, one or more sensors, and a wireless transmitter/receiver. Based upon sensor data and demand criteria programmed into the memory, the system provides late systolic impulse (LSI) therapy to treat congestive heart failure (CHF) and ventricle level-shifting (VLS) therapy to block unwanted PVCs to prevent VT or VF dynamically and use a phased array amplifier therapy to accurately manage CRT. An external echocardiogram and ultrasound system adjusts the therapies administered based upon sensor and demand data in real time to allow a patient's heart to function at a level of improved performance and increase ejection fraction EF.

In one embodiment, a method to alert a user of a wearable cardioverter defibrillator (WCD) is described. The method includes determining when a system issue is resolved and issuing an alert when the system issue is resolved. In some embodiments, the method may detect the system issue and issuing a system alert based at least in part on the system issue. The method may then monitor a status of the system issue. In some instances, the method may detect an abnormality in system operation sand determine a severity rating for the abnormality. The method may determine if the abnormality satisfies a time duration threshold based at least in part on the severity rating.

The device includes a cardiac therapy circuit with a first terminal, and a peripheral therapy circuit with a second terminal. These terminals can either receive a cardiac detection/stimulation lead and a peripheral detection/stimulation lead of an anatomical structure. The device is configured to recognize the leads and automatically configure the connection terminals. This includes discrimination methods for identifying the terminal on which a cardiac signal is detected, and switching methods for coupling the cardiac therapy circuit to the terminal and the peripheral therapy circuit to the other terminal.

Aspects of the present disclosure are directed toward a medical device having a a core assembly. The core assembly includes a core circuit assembly and a core assembly housing configured to enclose the core circuit assembly. The core assembly housing includes a first portion, and a second portion configured to be coupled to the first portion along a weld seam. The second portion includes at least one weld joint feature, which includes a thinned section of the second portion.

Implantable medical systems enter an exposure mode of operation, either manually via a down linked programming instruction or by automatic detection by the implantable system of exposure to a magnetic disturbance. A controller then determines the appropriate exposure mode by considering various pieces of information including the device type including whether the device has defibrillation capability, pre-exposure mode of therapy including which chambers have been paced, and pre-exposure cardiac activity that is either intrinsic or paced rates. Additional considerations may include determining whether a sensed rate during the exposure mode is physiologic or artificially produced by the magnetic disturbance. When the sensed rate is physiologic, then the controller uses the sensed rate to trigger pacing and otherwise uses asynchronous pacing at a fixed rate.

Implantable medical systems enter an exposure mode of operation, either manually via a down linked programming instruction or by automatic detection by the implantable system of exposure to a magnetic disturbance. A controller then determines the appropriate exposure mode by considering various pieces of information including the device type including whether the device has defibrillation capability, pre-exposure mode of therapy including which chambers have been paced, and pre-exposure cardiac activity that is either intrinsic or paced rates. Additional considerations may include determining whether a sensed rate during the exposure mode is physiologic or artificially produced by the magnetic disturbance. When the sensed rate is physiologic, then the controller uses the sensed rate to trigger pacing and otherwise uses asynchronous pacing at a fixed rate.

Techniques and systems for monitoring cardiac arrhythmias and delivering electrical stimulation therapy using a subcutaneous device (e.g. subcutaneous implantable (SD)) and a leadless pacing device (LPD) are described. In one or more embodiments, a computer-implemented method includes sensing a first electrical signal from a heart of a patient through a SD. The first signal is stored into memory and serves as a baseline rhythm for a patient. Subsequently, a second signal is sensed from the heart through the SD. A cardiac condition can be detected within the sensed second electrical signal through the SD. A determination is made as to whether cardiac resynchronization therapy (CRT) is appropriate to treat the detected cardiac condition. A determination can then be made as to the timing of pacing pulse delivery to cardiac tissue through a leadless pacing device (LPD). The LPD receives communication from the SD requesting the LPD to deliver CRT to the heart. The SD senses and extracts data from a third electrical signal from the heart of the patient to determine whether the pacing by LPD provided efficacious resynchronization or whether the delivery and timing of the LPD pulse should be modified.