Abstract: Devices, systems, and methods deliver implantable medical devices for ventricular-from-atrial (VfA) cardiac therapy. A VfA device may be implanted in the right atrium (RA) with an electrode extending from the right atrium into the left ventricular myocardium. A flexible leed, or another probe, may be advanced to the potential implantation site and used to identify a precise location for implantation of a medical device, such as an electrode, leadlet, lead, or intracardiac device. Some methods may include locating a potential implantation site in the triangle of Koch region in the right atrium of a patient's heart; attaching a fixation sheath to the right-atrial endocardium in the potential implantation site; and implanting the medical device over a guide wire at the potential implantation site. An implantable medical device may include an intracardiac housing and a leadlet, which may be delivered by these methods.

Abstract: An example fixation component for an implantable medical device (IMD) includes a base and a plurality of tines configured be deployed with a target deployment stiffness to engage tissue a target implant site while maintaining a target deflection stiffness after deployment. The base defines a longitudinal axis of the fixation component and is fixedly attached near the distal end of the IMD. Each tine is spaced apart from one another around a perimeter of the distal end of the IMD and extend from the base. A shape of each tine is selected to control each of the target deployment stiffness and target deflection stiffness.

Abstract: An intracardiac ventricular pacemaker includes a pulse generator for delivering ventricular pacing pulses, an impedance sensing circuit, and a control circuit in communication with the pulse generator and the impedance sensing circuit. The pacemaker is configured to produce an intraventricular impedance signal, detect an atrial systolic event using the intraventricular impedance signal, set an atrioventricular pacing interval in response to detecting the atrial systolic event, and deliver a ventricular pacing pulse in response to the atrioventricular pacing interval expiring.

Abstract: An intracardiac ventricular pacemaker includes a pulse generator for delivering ventricular pacing pulses, an impedance sensing circuit, and a control circuit in communication with the pulse generator and the impedance sensing circuit. The pacemaker is configured to produce an intraventricular impedance signal, detect an atrial systolic event using the intraventricular impedance signal, set an atrioventricular pacing interval in response to detecting the atrial systolic event, and deliver a ventricular pacing pulse in response to the atrioventricular pacing interval expiring.

Abstract: A medical system includes an implantable medical device that carries a first electrode on a distal end of the implantable medical device and a return electrode. The implantable medical device is configured to be positioned within a heart. The implantable medical device further includes a leadlet including a proximal end and a distal end. The proximal end is attached to the implantable medical device, and the distal end is configured to penetrate tissue of the heart. The leadlet carries a second electrode, and a body of the leadlet between the proximal end and the distal end is configured to flex when the distal end is implanted in the tissue of the heart. The implantable medical device further includes a fixation device attached to the implantable medical device. The fixation device is configured to affix the distal end of the implantable medical device to the heart.

Abstract: A device and method are described for transmitting tissue conductance communication (TCC) signals. A device may be is configured to establish a transmission window by transmitting a TCC test signal at multiple time points over a transmission test period to a receiving device and detect at least one response to the transmitted TCC test signals performed by the receiving device. The IMD is configured to establish the transmission window based on the at least one detected response so that the transmission window is correlated to a time of relative increased transimpedance between a transmitting electrode vector and receiving electrode vector during the transmission test period.

Abstract: A medical delivery device for delivering a medical device includes a navigable elongated member, a deployment bay, and a compression mechanism. The deployment bay may be configured to house the medical device as the medical device is navigated to the target site. The deployment bay may be at a distal end of the delivery device and may include a distal opening through which the medical device may be deployed. The compression mechanism is configured to longitudinally compress in response to a predetermined force such that the elongated member and deployment bay are relatively closer together along a longitudinal axis of the delivery device.

Abstract: A fixation mechanism of an implantable medical device is formed by a plurality of tines fixedly mounted around a perimeter of a distal end of the device. Each tine may be said to include a first segment fixedly attached to the device, a second segment extending from the first segment, and a third segment, to which the second segment extends. When the device is loaded in a lumen of a delivery tool and a rounded free distal end of each tine engages a sidewall that defines the lumen, to hold the tines in a spring-loaded condition, the first segment of each tine, which has a spring-biased pre-formed curvature, becomes relatively straightened, and the third segment of each tine, which is terminated by the free distal end, extends away from the axis of the device at an acute angle in a range from about 45 degrees to about 75 degrees.

Abstract: An implantable medical device assembly includes a mounting structure, an electrode protruding from a surface of the structure, between opposing sides thereof, and tissue-penetrating fixation tines, each extending from a corresponding shoulder of the structure surface, adjacent to the opposing sides. In a relaxed condition, each tine extends away from the surface and then bends toward a proximal end of the structure and back toward the surface. In an extended condition, each tine bends toward a distal end of the structure and extends along the corresponding shoulder. A holding member of a delivery tool has opposing sidewalls defining a cavity, wherein each sidewall includes a rail-like edge that fits in sliding engagement with a corresponding shoulder, to deform a corresponding tine into the extended condition, when an operator passes the assembly into the cavity. Applying a push force, to move the assembly back out form the cavity, releases the tines.

Abstract: A fixation mechanism of an implantable medical device is formed by a plurality of tines fixedly mounted around a perimeter of a distal end of the device. Each tine may be said to include a first segment fixedly attached to the device, a second segment extending from the first segment, and a third segment, to which the second segment extends. When the device is loaded in a lumen of a delivery tool and a rounded free distal end of each tine engages a sidewall that defines the lumen, to hold the tines in a spring-loaded condition, the first segment of each tine, which has a spring-biased pre-formed curvature, becomes relatively straightened, and the third segment of each tine, which is terminated by the free distal end, extends away from the axis of the device at an acute angle in a range from about 45 degrees to about 75 degrees.

Abstract: A medical system is configured to deliver an implantable medical device to a targeted implant site. The system may include a processor configured to receive a cardiac electrical signal and determine a feature of the cardiac electrical signal. The processor may be configured to determine a position of the delivery tool based on at least one feature of the cardiac electrical signal. The processor may detect a deployment position of the delivery tool in response to the cardiac electrical signal feature meeting criteria for detecting the deployment position.

Abstract: A device for delivering an implantable medical device (IMD) includes an elongated member and a deployment bay configured to house the IMD, the deployment bay defining a distal opening for deploying the IMD out of the deployment bay. The device includes a first electrode located inside the deployment bay during intravascular navigation, a second electrode, and impedance detection circuitry configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of a fluid or tissue of the patient. The device also includes processing circuitry configured to determine an impedance of the path based on the signal and control a user interface to indicate when an impedance of the path indicates that at least one of the IMD or the distal opening is in a fixation configuration relative to the target site of the patient.

Abstract: An example fixation component for an implantable medical device (IMD) includes a base and a plurality of tines configured be deployed with a target deployment stiffness to engage tissue a target implant site while maintaining a target deflection stiffness after deployment. The base defines a longitudinal axis of the fixation component and is fixedly attached near the distal end of the IMD. Each tine is spaced apart from one another around a perimeter of the distal end of the IMD and extend from the base. A shape of each tine is selected to control each of the target deployment stiffness and target deflection stiffness.

Abstract: Devices, systems, and methods deliver implantable medical devices for ventricular-from-atrial (VfA) cardiac therapy. A VfA device may be implanted in the right atrium (RA) with an electrode extending from the right atrium into the left ventricular myocardium. A flexible leed, or another probe, may be advanced to the potential implantation site and used to identify a precise location for implantation of a medical device, such as an electrode, leadlet, lead, or intracardiac device. Some methods may include locating a potential implantation site in the triangle of Koch region in the right atrium of a patient's heart; attaching a fixation sheath to the right-atrial endocardium in the potential implantation site; and implanting the medical device over a guide wire at the potential implantation site. An implantable medical device may include an intracardiac housing and a leadlet, which may be delivered by these methods.

Abstract: An example implantable medical device (IMD) retrieval system may include an elongate outer tubular member including a longitudinally extending lumen terminating in a distal cup that is configured to receive the IMD; and a retrieval assembly including a retrieval member that includes an elongate member terminating in at least one snare that is moveable between an expanded configuration and a contracted configuration; and a fixed-curve catheter that includes a resilient material forming a distal curve and defining a lumen in which the retrieval member extends in sliding engagement, where the fixed-curve catheter extends in sliding engagement within the lumen of the elongate outer tubular member.

Abstract: An intracardiac ventricular pacemaker includes a pulse generator for delivering ventricular pacing pulses, an impedance sensing circuit, and a control circuit in communication with the pulse generator and the impedance sensing circuit. The pacemaker is configured to produce an intraventricular impedance signal, detect an atrial systolic event using the intraventricular impedance signal, set an atrioventricular pacing interval in response to detecting the atrial systolic event, and deliver a ventricular pacing pulse in response to the atrioventricular pacing interval expiring.

Abstract: A device for delivering an implantable medical device (IMD) includes an elongated member and a deployment bay configured to house the IMD, the deployment bay defining a distal opening for deploying the IMD out of the deployment bay. The device includes a first electrode located inside the deployment bay during intravascular navigation, a second electrode, and impedance detection circuitry configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of a fluid or tissue of the patient. The device also includes processing circuitry configured to determine an impedance of the path based on the signal and control a user interface to indicate when an impedance of the path indicates that at least one of the IMD or the distal opening is in a fixation configuration relative to the target site of the patient.

Abstract: A medical delivery device for delivering a medical device includes a navigable elongated member, a deployment bay, and a compression mechanism. The deployment bay may be configured to house the medical device as the medical device is navigated to the target site. The deployment bay may be at a distal end of the delivery device and may include a distal opening through which the medical device may be deployed. The compression mechanism is configured to longitudinally compress in response to a predetermined force such that the elongated member and deployment bay are relatively closer together along a longitudinal axis of the delivery device.

Abstract: Delivery tools of interventional medical systems facilitate deployment of relatively compact implantable medical devices that include extensions, for example, cardiac pacing devices that include an extension for atrial sensing, wherein an entirety of the device is contained within the delivery tool while a distal-most portion of the tool is navigated to a target implant site. Once at the implant site, a device fixation member may be exposed out from a distal opening of the tool, for initial deployment, while the extension remains contained within the delivery tool. The tool includes a grasping mechanism, operable, within and without a lumen of the tool, to alternately grip and release the device extension, for example, to position a distal end of the extension after the tool has been withdrawn from over an entirety of the initially deployed device.

Abstract: An implantable medical device assembly includes a mounting structure, an electrode protruding from a surface of the structure, between opposing sides thereof, and tissue-penetrating fixation tines, each extending from a corresponding shoulder of the structure surface, adjacent to the opposing sides. In a relaxed condition, each tine extends away from the surface and then bends toward a proximal end of the structure and back toward the surface. In an extended condition, each tine bends toward a distal end of the structure and extends along the corresponding shoulder. A holding member of a delivery tool has opposing sidewalls defining a cavity, wherein each sidewall includes a rail-like edge that fits in sliding engagement with a corresponding shoulder, to deform a corresponding tine into the extended condition, when an operator passes the assembly into the cavity. Applying a push force, to move the assembly back out form the cavity, releases the tines.