A system and method for extra cardiac defibrillation is disclosed. In a particular embodiment, an extra cardiac implantable cardioverter defibrillator system includes an implantable defibrillator having a metal case and a defibrillation lead. The defibrillation lead has a connector at its proximal end for coupling to the implantable defibrillator and a first defibrillation coil electrode at a distal portion of the lead. The first defibrillation electrode configured to be disposed in an inferior vena cava.

An implantable medical device performs a method that includes detecting a cardiac event interval that is greater than a P-wave oversensing threshold interval. In response to detecting the cardiac event interval greater than the P-wave oversensing threshold interval, the device determines the amplitude of the sensed cardiac signal and withholds restarting a pacing interval in response to the amplitude satisfying P-wave oversensing criteria. A pacing pulse may be generated in response to the pacing interval expiring without sensing an intrinsic cardiac electrical event that is not detected as a P-wave oversensing event.

Methods and tool kits for implanting a lead subcutaneously. Examples include tool kits and methods for establishing first and second subcutaneous tunnels at an angle relative to one another to facilitate introduction of a lead to the subcutaneous space. In an example, a tunneling tool and lead assembly are advanced simultaneously into the subcutaneous space. The tunneling tool may include a curved region configured to transition the tool from the first subcutaneous tunnel to the second subcutaneous tunnel with the use of a single incision.

In some examples, a tool for, e.g., creating a sub-sternal tunnel in a patient or other use, is described. The tool may include a handle and a tunneling shaft coupled to the handle. The tunneling shaft extends from a proximal end to a distal end, and at least a portion of the tunneling shaft extends in a curved orientation between the first end to the distal end. The distal end of the tunneling shaft includes a cutting tool having a sharp edge. The cutting tool is moveable from a recessed position in which the sharp edge of the cutting tool is recessed into the distal end of the tunneling shaft to a deployed position in which the sharp edge of the cutting tool extends beyond the distal end of the tunneling shaft in the deployed position, e.g., to cut pericardium, scar tissue, and/or connective tissue with the sharp edge.

A medical device is configured to sense an acceleration signal and determine at least one frequency metric from the acceleration signal that is correlated to a frequency of oscillations of the acceleration signal. The medial device is configured to determine that the at least one frequency metric meets atrial tachyarrhythmia criteria and detect an atrial tachyarrhythmia in response to at least the frequency metric meeting the atrial tachyarrhythmia criteria.

Various embodiments of a sealed package and a method of forming such package are disclosed. The package includes a housing, a substrate hermetically sealed to the housing, and a light source disposed on a first major surface of the substrate. The package further includes a detector disposed on the first major surface of the substrate and having a detecting surface. The package also includes a masking layer disposed on at least one of the first major surface and a second major surface of the substrate, where the masking layer includes a first aperture aligned with an emission axis of the light source in a direction orthogonal to the first major surface of the substrate. The masking layer further includes a second aperture aligned with a detection axis of the detector in a direction orthogonal to the first major surface of the substrate.

In some examples, a coil electrode assembly includes a coil electrode including a plurality of windings and extending from an electrode proximal end to an electrode distal end, the coil electrode defining an electrode lumen from the electrode proximal end to the electrode distal end. The coil electrode assembly further includes an insulative tube extending within the lumen of the coil electrode such that the coil electrode extends along an outer surface of the insulative tube. The coil electrode is partially embedded within the insulative tube when the insulative tube is in an expanded state to maintain a spacing between the windings.

Systems and methods for implanting a medical device include an implantable lead comprising a lead body having a distal end and a proximal end. The implantable lead has electrodes positioned at the distal end and has a lead connector positioned at the proximal end. The lead connector includes lead contacts that are communicatively coupled to the electrodes positioned at the distal end. The lead body has a body outer envelope configured to fit within a lumen of an introducer sheath and the lead connector has a connector outer envelope configured to fit within the lumen of the introducer sheath. A pulse generator has a connector cavity. The lead adaptor is configured to interconnect the implantable lead and the pulse generator. The lead adaptor has an insertable connector that includes mating contacts and an adaptor cavity that includes cavity contacts. The cavity contacts are positioned to engage the lead contacts of the lead connector when the lead connector is inserted into the adaptor cavity. The insertable connector is configured to be inserted into the connector cavity of the pulse generator.

An implantable medical system may provide atrioventricular synchronous pacing using the ventricular septal wall. The system may include a ventricular electrode coupled to an intracardiac housing or a first medical lead implantable in the ventricular septal wall of the patient's heart to deliver cardiac therapy to or sense electrical activity of the left ventricle of the patient's heart and a right atrial electrode coupled to a leadlet or second medical lead to deliver cardiac therapy to or sense electrical activity of the right atrium of the patient's heart. A right ventricular electrode may be coupled to the intracardiac housing or the first medical lead and implantable in the ventricular septal wall of the patient's heart to deliver cardiac therapy to or sense electrical activity of the right ventricle of the patient's heart.

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.