Implant delivery and retrieval systems and methods

Implementations described and claimed herein provide systems and methods for delivering and retrieving a leadless pacemaker. In one implementation, a leadless pacemaker has a docking end, and the docking end has a docking projection extending from a surface. A docking cap has a body defining a chamber. A retriever has sheaths extending with lumens distally from the chamber. A snare extends between the lumens forming a first snare loop pointing in a first direction and a second snare loop pointing in a second direction with a docking space formed therebetween. The snare is movable between an engaged position and a disengaged position by translating the first snare wire and the second snare wire within the first snare lumen and the second snare lumen. The engaged position includes the first snare wire and the second snare wire tightened around the docking projection within the docking space.

FIELD

The present disclosure relates to leadless pacemakers and related delivery and retrieval systems and methods. More particularly, the present disclosure relates to systems and methods for loading a leadless pacemaker onto a catheter system for delivery to or retrieval from an implant site.

BACKGROUND

Cardiac pacing by an artificial pacemaker provides an electrical stimulation of the heart when its own natural pacemaker and/or conduction system fails to provide synchronized atrial and ventricular contractions at rates and intervals sufficient for a patient's health. Such antibradycardial pacing provides relief from symptoms and even life support for hundreds of thousands of patients. Cardiac pacing may also provide electrical overdrive stimulation to suppress or convert tachyarrhythmias, again supplying relief from symptoms and preventing or terminating arrhythmias that could lead to sudden cardiac death.

Cardiac pacing by currently available or conventional pacemakers is usually performed by a pulse generator implanted subcutaneously or sub-muscularly in or near a patient's pectoral region. Pulse generator parameters are usually interrogated and modified by a programming device outside the body, via a loosely-coupled transformer with one inductance within the body and another outside, or via electromagnetic radiation with one antenna within the body and another outside. The generator usually connects to the proximal end of one or more implanted leads, the distal end of which contains one or more electrodes for positioning adjacent to the inside or outside wall of a cardiac chamber. The leads have an insulated electrical conductor or conductors for connecting the pulse generator to electrodes in the heart. Such electrode leads typically have lengths of 50 to 70 centimeters.

Although more than one hundred thousand conventional cardiac pacing systems are implanted annually, various well-known difficulties exist. For example, a pulse generator, when located subcutaneously, presents a bulge in the skin that patients can find unsightly, unpleasant, or irritating, and which patients can subconsciously or obsessively manipulate. Even without persistent manipulation, subcutaneous pulse generators can exhibit erosion, extrusion, infection, and disconnection, insulation damage, or conductor breakage at the wire leads. Although sub-muscular or abdominal placement can address some concerns, such placement involves a more difficult surgical procedure for implantation and adjustment, which can prolong patient recovery.

A conventional pulse generator, whether pectoral or abdominal, has an interface for connection to and disconnection from the electrode leads that carry signals to and from the heart. Usually at least one male connector molding has at least one terminal pin at the proximal end of the electrode lead. The male connector mates with a corresponding female connector molding and terminal block within the connector molding at the pulse generator. Usually a setscrew is threaded in at least one terminal block per electrode lead to secure the connection electrically and mechanically. One or more O-rings usually are also supplied to help maintain electrical isolation between the connector moldings. A setscrew cap or slotted cover is typically included to provide electrical insulation of the setscrew. This briefly described complex connection between connectors and leads provides multiple opportunities for malfunction.

Other problematic aspects of conventional pacemakers relate to the separately implanted pulse generator and the pacing leads. By way of another example, the pacing leads, in particular, can become a site of infection and morbidity. Many of the issues associated with conventional pacemakers are resolved by the development of a self-contained and self-sustainable pacemaker, or so-called leadless pacemaker.

Similar to active fixation implantable leads used with conventional pulse generators, leadless pacemakers are typically fixed to an intracardial implant site by an actively engaging mechanism such as a screw or helical member that threads into the myocardium. Leadless pacemakers are often delivered to an intracardial implant site via a delivery system including a delivery catheter. Conventional delivery catheter systems are typically long (e.g., approximately 42 mm or longer), making navigation of the patient anatomy difficult and increasing a footprint of the system at the implant site.

Some conventional delivery systems are tether based in which attachment of the leadless pacemaker to the delivery catheter is dependent on the tether alignment. Once the tether alignment is lost, which may occur due to system tolerances or anatomical interferences, among other factors, the leadless pacemaker may spontaneously release from the delivery catheter. Such a spontaneous release may cause embolism, a need to retrieve the leadless pacemaker, and/or other patient risks. Retrieval may be performed by removing the delivery catheter and introducing a retrieval catheter to remove the leadless pacemaker. The delivery catheter system is generally different in structure and operation from the retrieval catheter system, which increases procedure time, complexity, and cost. If retrieval cannot be performed using a retrieval catheter system, the leadless pacemaker is typically retrieved through surgery, further complicating the procedure. Moreover, implanting a second leadless pacemaker into a patient often requires the use of a second catheter delivery system, as many conventional catheter systems fail to accommodate bed-side loading of leadless pacemakers onto a previously used catheter system. Instead, many conventional catheter systems are preloaded during manufacturing. It is with these observations in mind, among others, that the presently disclosed technology was conceived and developed.

SUMMARY OF THE DISCLOSURE

Implementations described and claimed herein address the foregoing observations by providing systems and methods for delivering and retrieving a leadless pacemaker. In one implementation, a leadless pacemaker has a docking end, and the docking end has a docking projection extending from a surface. A docking cap has a body defining a chamber. The docking cap has a proximal opening into the chamber, and the proximal opening is coaxial with a longitudinal axis of a lumen of a catheter. A retriever has a first sheath and a second sheath extending distally from the chamber. The first sheath has a first lumen, and the second sheath has a second lumen. A snare includes a first snare wire and a second snare wire. The first snare wire extends from the first snare lumen into the second snare lumen forming a first snare loop pointing in a first direction, and the second snare wire extends from the first snare lumen into the second snare lumen forming a second snare loop pointing in a second direction different from the first direction. The first snare loop and the second snare loop form a docking space. The snare is movable between an engaged position and a disengaged position by translating the first snare wire and the second snare wire within the first snare lumen and the second snare lumen. The engaged position includes the first snare wire and the second snare wire tightened around the docking projection within the docking space.

In another implementation, a docking cap has a body defining a chamber. A retriever has a first sheath and a second sheath extending distally from the chamber. The first sheath is disposed at a position radially opposite to the second sheath relative to a central axis. The first sheath has a first lumen, and the second sheath has a second lumen. A snare includes a first snare wire and a second snare wire. The first snare wire extends from the first snare lumen into the second snare lumen forming a first snare loop having a first peak at the central axis. The second snare wire extends from the first snare lumen into the second snare lumen forming a second snare loop having a second peak at the central axis. The snare is movable between an engaged position and a disengaged position by translating the first snare wire and the second snare wire within the first snare lumen and the second snare lumen. The translation of the first snare wire and the second snare wire move the first peak radially inwards toward the second peak to the engaged position and radially outwards away from the second peak to the disengaged position.

In yet another implementation, a docking space is disposed relative to a docking projection extending from a surface of a body of a leadless pacemaker. The docking space is formed by a first snare loop pointing in a first direction and a second direction different than the first direction. The first snare loop is formed from a first snare wire extending from a first snare lumen of a first sheath into a second snare lumen of a second sheath. The second snare loop is formed from a second snare wire extending from the first snare lumen of the first sheath into the second snare lumen of the second sheath. The first snare loop and the second snare loop are advanced over the leadless pacemaker until the docking projection is disposed in the docking space. A size of the docking space is decreased by retracting the first snare wire and the second snare wire into the first snare lumen and the second snare lumen until the first snare wire and the second snare wire tighten around the docking projection. The first sheath and the second sheath are retracted into a lumen of a catheter until the docking projection is positioned within a chamber of a docking cap.

In still another implementation, a leadless pacemaker has a docking end, and the docking end having a docking projection extending from a surface. A docking cap has a body defining a chamber. The docking cap has a proximal opening into the chamber. The proximal opening is coaxial with a longitudinal axis of a lumen of a catheter. A retriever has a flexible grasper with a first arm disposed opposite a second arm. Each of the first arm and the second arm form a hinge biased radially outwards from the longitudinal axis. The docking cap locks the first arm and the second arm on the docking projection when the body is sheathed over the retriever until the flexible grasper is disposed within the chamber.

In another implementation, a flexible grasper is disposed relative to a docking projection extending from a surface of a body of a leadless pacemaker. The flexible grasper has a first arm disposed opposite a second arm. Each of the first arm and the second arm forms a hinge biased radially outwards from a longitudinal axis. The docking projection is posited between the first arm and the second arm. A body of a docking cap is sheathed over the flexible grasper. The docking cap locks the first arm and the second arm on the docking projection by one or more cap surfaces disposed relative to the chamber displacing the first arm and the second arm radially inwards holding the first arm and the second arm in compression around the docking projection.

In yet another implementation, a leadless pacemaker has a docking end, and the docking end has an opening defined in a surface. A retriever has a first arm disposed opposite a second arm around a central lumen. Each of the first arm and the second arm forms a hinge biased radially inwards towards the central lumen. The first arm and the second arm are displaceable radially outwards by a mandrel translated through the central lumen towards the docking end. The radial outward displacement of the first arm and the second arm engages the surface of the docking end within the opening.

DETAILED DESCRIPTION

Aspects of the present disclosure involve systems and methods for delivering and retrieving a leadless biostimulator, such as a leadless pacemaker. Generally, the leadless pacemaker is delivered and retrieved from an implant location in a patient using a catheter system. The presently disclosed systems and methods thus facilitate repeated implantation and/or retrieval of leadless pacemakers via a single catheter delivery and retrieval system, thereby reducing waste and the costs associated therewith. Additionally, the systems and methods described herein permit a single catheter system to deliver and retrieve different leadless pacemakers having varying configurations further reducing the operation burden of stocking multiple systems applicable to the various configurations.

In one aspect, the catheter system includes a retriever in the form of a grasper, a snare, and/or the like, releasably engagable to a docking end of the leadless pacemaker to provide torque transmission to the leadless pacemaker during deployment, as well as providing the engagement, delivery, detachment, and/or retrieval of the leadless pacemaker. The retriever reduces the risk of spontaneous or otherwise undesired release of the leadless pacemaker from the catheter during delivery or retrieval. Moreover, the retriever provides reliable detachment independent of a relative position of a dual-tether system and isolates rotation forces of the leadless pacemaker from the catheter system, which may otherwise cause binding and/or torque-wind in a dual-tether system. Tool-less, bed-side loading is facilitated with the presently disclosed technology, permitting the deployment of multiple leadless pacemakers into the patient anatomy with reduced tissue trauma to the patient anatomy during deployment due to the radial opening of the retriever.

The systems and methods described herein generally relate to a loading tool having a retriever for releasably engaging a docking projection of a medical implant, as well as to methods of delivering and retrieving the same. While the present disclosure is discussed with reference to leadless cardiac pacemakers and torque as a loading technique, it will be appreciated that the presently disclosed technology is applicable to other biostimulators and/or medical implant systems and methods as well as loading techniques.

To begin a detailed description of an example cardiac pacing system100having one or more leadless pacemakers104, reference is made toFIG. 1. The leadless pacemakers104may each be configured for temporary leadless pacing of a patient heart102. In one implementation, each of the leadless pacemakers104is configured for placement on or attachment to the inside or outside of a cardiac chamber, such as the right atrium and/or right ventricle, of the patient heart102. The leadless pacemakers104may be attached to cardiac tissue of the patient heart102, for example, via a helical anchor106that is threaded through the myocardium. It will be appreciated, however, that other primary fixation mechanisms, as well as secondary fixation mechanisms in some cases, may be used to attach the leadless pacemaker104to tissue or otherwise restrict movement of the leadless pacemaker104during implantation.

The leadless pacemakers104are delivered to and/or retrieved from the patient heart102using a catheter system108, as shown inFIG. 2. Generally, the catheter system108releasably engages the leadless pacemaker104for intravenous advancement into the patient heart102. The catheter system108engages the leadless pacemaker104in such a manner as to facilitate fixation to cardiac tissue, for example, using the helical anchor106. As described herein, where the fixation mechanism engages the cardiac tissue through rotation, such as with the helical anchor106, the catheter system108is adapted to provide torque transmission to the leadless pacemaker104. Stated differently, the catheter system108engages features of the leadless pacemaker104to apply torque to the leadless pacemaker104to screw the helical anchor106into cardiac tissue.

The catheter system108engages the leadless pacemaker104at a distal end110and includes a handle at a proximal end112for directing the delivery and/or retrieval of the leadless pacemaker104. In one implementation, the catheter system108includes a torque shaft114, a sleeve116, and an introducer sheath120. The catheter system108may also include a steerable catheter116for deflecting the catheter system108and/or one or more flush ports128and130for flushing saline or other fluids through the catheter system118.

The torque shaft114provides torque transmission to the leadless pacemaker104from the steerable catheter118and otherwise directs movement of the leadless pacemaker104as controlled by one or more steering knobs (e.g., a first steering knob124and a second steering knob126) disposed on a handle body122. The introducer sheath120can be advanced distally over the steerable catheter118to provide additional steering and support for the steerable catheter118during delivery and/or retrieval and to surround the leadless pacemaker104as it is introduced through a trocar or introducer into the patient anatomy. Similarly, the sleeve116is movable along the steerable catheter118and may be displaced distally over the leadless pacemaker104to cover the torque shaft114, the leadless pacemaker104, and the helical anchor106to protect patient tissue and anatomy during delivery and/or retrieval.

Turning toFIG. 3, a detailed view of the distal end110of the catheter system118is shown. In one implementation, the steerable catheter118extends through a sleeve cap134into the sleeve116where it is engaged to the torque shaft114. The sleeve116may be displaceable over the torque shaft114and leadless pacemaker104such that the leadless pacemaker104is within the sleeve116proximal to a distal edge132of the sleeve116. The sleeve116may also be steerable.

In one implementation, a distal end of the torque shaft114is engaged to a docking cap136, which is configured to releasably engage the leadless pacemaker104. The torque shaft114and the docking cap136each deliver torque to the leadless pacemaker104during delivery and/or retrieval.FIGS. 4A-4Cillustrate the catheter system108in a docked or engaged position with the docking cap136sheathed over a docking end of the leadless pacemaker104. In one implementation, the docking cap136includes a body138and a receiving portion140configured to engage a distal end146of the torque shaft114. The distal end146of the torque shaft114may remain rigidly attached to the receiving portion140during use.

The body138of the docking cap136defines a chamber142. As can be understood fromFIGS. 4B-4C, a docking projection148extending from the docking end of the leadless pacemaker104is disposed within the chamber142in the docked position. A retriever144is displaceable within a lumen of the torque shaft114and configured to releasably engage the docking projection148. More particularly, the retriever144is extendable through the body138of the docking cap136for placement relative to the docking projection148, and the body138of the docking cap136is sheathed over the docking projection148causing the retriever144to capture the docking projection148within the chamber142.

In the docked position, the catheter system108provides torque transmission to the leadless pacemaker104.FIG. 5illustrates that during a test mode or to reposition or otherwise manipulate the leadless pacemaker104during deployment, the torque shaft114is torqueable and adjustable with a freedom of movement in a plurality of directions. The torque shaft114may be flexible and/or made from a variety of materials. For example, the torque shaft114may be made from a polymer, metal, and/or the like. The torque shaft114may be made with a catheter lamination construction, formed as a hollow helical cable, and/or in other configurations for torque transmission and steering. In one implementation, the torque shaft114and/or the steerable catheter118is a hypo tube. In other implementations, the torque shaft114and/or the steerable catheter118includes a cable tube, a laser cut tube, an extrusion, a wire, a wire cable, and/or the like for increased flexibility.

As can be understood fromFIG. 6, the docking cap136is displaceable over the retriever144to cause the retriever144to move between an engaged position where the retriever144is engaged to the docking projection148within the chamber142and the catheter system108is docked to the leadless pacemaker104and a disengaged position where the retriever144is disposed in its natural state outside the chamber142and disengaged from the docking projection148. As shown inFIGS. 6 and 7, in one implementation, the docking cap136is retracting proximally causing the retriever144to open radially to its natural state, thereby releasing the docking projection148and disengaging the leadless pacemaker104. To recapture the leadless pacemaker for retrieval, repositioning, and/or the like, the retriever144is positioned relative to the docking projection148and the docking cap136is sheathed over the retriever144causing the retriever144to close radially over the docking projection148within the chamber142.

In one implementation, the retriever144is a flexible grasper with a first arm disposed opposite a second arm that each form a hinge biased radially outwards from a longitudinal axis of the retriever144. Stated differently, the retriever144is biased open in its natural state in free space, as shown inFIGS. 6 and 7. In one implementation, the natural state of the retriever144provides an opening defined by the arms with an inner diameter that is larger than a diameter of the docking projection148and in some examples a body of the leadless pacemaker104. The retriever144in the form of a flexible grasper may be made from a variety of elastic or otherwise flexible materials, including, but not limited to, Nitinol or other memory wire, cable, tubing, and/or the like.

As can be understood fromFIGS. 4A-7, the docking cap136translates axially over the retriever144to move the catheter system108between the docked and released positions. In one implementation, the body138of the docking cap136includes one or more cap surfaces disposed relative to the chamber142. The cap surfaces displace the arms of the retriever144radially inwards to hold the arms in compression around the docking projection148. As such, the docking cap136and the docking end of the leadless pacemaker104are configured such that the retriever144remains locked on the docking projection148when the docking cap136is sheathed over the retriever144. This docked position facilitates delivery through the patient anatomy to a target location in the patient heart102for implantation. Once implanted, the docking cap136is retracted proximally, allowing the arms of the retriever144to open radially outwards to the natural state and thereby releasing the docking projection148. The catheter system108is then removed from the patient. The docking projection148may be recaptured for retrieval or repositioning by sheathing the docking cap136over the retriever144. During release and capture, tugging on or trauma to patient tissue is reduced or eliminated with the radial movement of the arms of the retriever144between the engaged and disengaged positions.

FIGS. 8 and 9show examples of the retriever144in the form of a flexible grasper with a first arm200and a second arm202each forming a flexible loop attached to one or more mandrels extending through a lumen of the torque shaft114. In one implementation, the first arm200includes one or more elongated bodies (e.g., a first elongated body206and a second elongated body208). The first elongated body206may extend parallel to the second elongated body208within a first plane with a gap formed therebetween. A set of tapering portions connect the one or more elongated bodies to a set of grasping portions. In one implementation, a first grasping portion214is connected to the first elongated body206with a first tapering portion210on the first plane, and a second grasping portion216is connected to the second elongated body208with a second tapering portion212on the first plane. The first grasping portion214is generally parallel to the second grasping portion216and the first and second elongated bodies206and208. A distance between the first and second grasping portions214and216is larger than a distance between the first and second elongated bodies206and208, such that the first and second tapering portions210and212extend inwardly from the first and second grasping portions214and216to the first and second elongated bodies206and208. The flexible loop of the first arm200is formed by a first looped portion218extending along a curve between the first and second grasping portions214and216.

The second arm202may mirror the first arm200. In one implementation, the second arm202includes one or more elongated bodies (e.g., a third elongated body220and a fourth elongated body222). The third elongated body220may extend parallel to the fourth elongated body222within a second plane with a gap formed therebetween. The second plane is parallel to the first plane. A second set of tapering portions connect the one or more elongated bodies to a second set of grasping portions. In one implementation, a third grasping portion228is connected to the third elongated body220with a third tapering portion224on the second plane, and a fourth grasping portion230is connected to the fourth elongated body222with a fourth tapering portion226on the second plane. The third grasping portion228is generally parallel to the fourth grasping portion230and the third and fourth elongated bodies220and222. A distance between the third and fourth grasping portions228and230is larger than a distance between the third and fourth elongated bodies220and222, such that the third and fourth tapering portions224and226extend inwardly from the third and fourth grasping portions228and230to the third and fourth elongated bodies220and222. The flexible loop of the second arm202is formed by a second looped portion232extending along a curve between the third and fourth grasping portions228and230.

As can be understood fromFIGS. 8 and 9, which show the docked position and the natural state of the retriever144, respectively, in one implementation, the first arm200and the second arm202each form a hinge biased radially outwards from a longitudinal axis of the retriever144. When the retriever144is in the docked position, the first set of grasping portions214and216are positioned adjacent the second set of grasping portions228and230within the first and second planes. In the docked position, the first and second looped portions218and232extend in opposite directions, forming a ring defining a docking space234therebetween. The docking space234may be sized and shaped to match a size and shape of the docking projection148with the first arm200and second arm202adapted to matingly engage the features of the docking projection148as described herein.

In moving to the natural state, the first arm200and the second arm202hinge radially outward from the longitudinal axis such that the first set of grasping portions214and216are positioned at an angle relative to the second set of grasping portions228and230with each at an angle relative to the first and second planes. In one implementation, when the docking cap136is retracted proximally, the ring formed by the first and second looped portions218and232opens radially outwards to a larger diameter, thus releasing the docking projection148.

Turning toFIGS. 10A-10B, the docking projection148may include features adapted to matingly engage with the first arm200and the second arm202and the docking cap136to facilitate capture by the retriever144and to provide torque transmission. In one implementation, the leadless pacemaker104includes the docking projection148extending from a surface302at a docking end of a body300. The docking projection148includes one or more docking surfaces, including edge docking surfaces306, an end surface308, and/or the like, configured to matingly engage corresponding cap surfaces disposed relative to the chamber142of the docking cap136, thereby providing torque transmission to the leadless pacemaker104. In one implementation, the edge docking surfaces306include one or more flat radial surfaces that may be radially symmetrical about the docking projection148. The edge docking surfaces306may be disposed relative to the end surface308forming a ledge extending transverse to the end surface308. In one implementation, the end surface308is flat and the surface302of the body300is flat providing additional surfaces for torque transmission.

The docking surfaces may include one or more keys adapted to matingly engage corresponding features of the docking cap136and/or the retriever144. The docking projection148and/or the surface302of the docking end of the body300may include one or more of the keys. In one implementation, the docking projection148includes side keys310extending through the docking projection148from the surface302of the body300to the end surface308. The side keys310may be oriented relative to each other on opposite sides, such that they are radially symmetric. As shown inFIG. 11, in one implementation, the side keys310are adapted to matingly engage a portion of the first arm200and the second arm202of the retriever144in the engaged position. For example, the grasping portions214,216,228, and230may be displaced during sheathing of the docking cap136into the side keys310where the docking cap136holds them in place in the engaged position. The side keys310may include one or more key surfaces312for torque transmission via the first arm200and the second arm202of the retriever144.

Similarly, the docking projection148may include a neck304indented from the edge docking surfaces306and adapted to matingly engage at least a portion of the first arm200and the second arm202of the retriever144. For example, the docking cap136may hinge the first and second looped portions214and232radially inwards into the neck304, where the docking cap136holds the first and second looped portions214and232in compression around the docking projection148in the engaged position. The indentation of the neck304prevents the first and second arms200and202from translating longitudinally and disengaging from the docking projection148. The geometry of the docking projection148facilitates a smooth capture and release by the retriever144when the docking cap136is sheathed distally or retracted proximally.

Referring toFIG. 12, the body138of docking cap136includes one or more cap surfaces disposed relative to the chamber142adapted to matingly engage the docking surfaces of the docking end of the leadless pacemaker104and/or features of the retriever144. In one implementation, the one or more cap surfaces include a distal end surface400, a proximal chamber surface402, and one or more side surfaces404extending between the proximal chamber surface402and one or more ledge surfaces406disposed proximal to the distal end surface400within the chamber142. The distal end surface400defines an opening into the chamber132, and the proximal chamber surface402defines a proximal opening408into the chamber142extending through the receiving portion140. The proximal opening408is coaxial with the longitudinal axis of a lumen of the torque shaft114and the retriever144.

The ledge surfaces406may mirror a size and shape of the surface302of the docking end of the body300of the leadless pacemaker104. For example, both the ledge surfaces406and the surface302may be flat. Similarly, the proximal chamber surface402may be sized and shaped to matingly engage the end surface308of the docking projection148, and the side surfaces404matingly engage the edge docking surfaces306. The mating engagement of each of the various cap surfaces with the corresponding docking surfaces provides torque transmission. When in the docking position, the engagement of the docking projection148with the docking cap136generates approximately 1.5 in-oz of torque with a mating normal force of approximately 500 g. The torque generated is thus an order of magnitude higher than the 0.125 in-oz or less of torque generally needed to implant a leadless pacemaker into human tissue.

Examples of various geometries of the docking end of the leadless pacemaker104are shown inFIGS. 13-18. The geometries include one or more keys in the form of torque transmission keys, dimples, and/or geometric interference features that matingly engage with corresponding features on the docking cap136. Turning first toFIG. 13, in one implementation, the surface302of the body300includes one or more undercut keys314defined therein. Alternatively or additionally, the docking projection148may have a cross-shape as shown inFIGS. 14A-14Cwith the side keys310forming angled cutouts.

In another implementation, the end surface308of the docking projection148is rounded, as shown inFIGS. 15A-18. A profile of the end surface308may have a variety of lengths from a lower profile curve to a higher dome shaped profile, each with the end surface308being a non-traumatic smooth round surface. The docking cap136includes corresponding cap surfaces mirroring the size and shape of the end surface308to hold the retriever144in compression against the docking projection148in the engaged position. Frictional contact between the cap surfaces and the end surface308provide torque transmission. To further facilitate torque transmission, the end surface308may include the keys310adapted to matingly engage cap keys410, as can be understood fromFIGS. 16A-18. To increase the friction of the mating surfaces, an overmolding412made from silicone or a similar material may be applied to the cap surfaces within the chamber142and/or on the docking projection148, as shown inFIGS. 19A-19B.

Referring toFIGS. 17A-18, the helical anchor106is disposed on a fixing end of the leadless pacemaker104opposite the docking end. In one implementation, the fixing end is at the distal end of the leadless pacemaker104, and the docking end is at the proximal end. It will be appreciated that some or all of these features may be reversed (stand-proud of their surface) depending on size restraints of the leadless pacemaker104.

For a detailed description of another example of the retriever144in the form of a flexible grasper and a corresponding example of the docking projection148, reference is made toFIGS. 20-26C. Turning first toFIG. 20, in one implementation, the docking projection148includes a docking button320mounted to the end surface308with one or more posts (e.g., first and second posts316and318). As can be understood fromFIG. 21, the docking button320may be integral with the posts316and318and be a rounded surface extending between a first end322and a second end324.

As shown inFIGS. 21 and 22, the retriever144includes a mandrel500connected to a base504. The mandrel500may be connected directly to the base504or indirectly via a retriever shaft502. The mandrel500extends through the proximal opening408and into the lumen of the torque shaft114. The retriever144may be made from a variety of elastic or otherwise flexible materials, including, but not limited to, a polymer (e.g., polyether ether ketone (PEEK)), Nitinol or other memory wire, cable, tubing, and/or the like.

The retriever144includes a first arm506and a second arm508extending from the base504and defining a docking space514therebetween. In one implementation, the first and second arms506and508form a jaw with hinges adapted to grasp at least a portion of the docking projection148, such as the docking button320, in the docking space514when the docking cap136is sheathed over retriever144into the docked position. In another implementation, one or more hinges are disposed at the connection points between the arms506and508and the base504. The first arm506may include a first lip510, and the second arm508may include a second lip512. Each of the lips510and512extends inwardly towards a longitudinal axis of a lumen516of the retriever144.

As illustrated inFIG. 23, in one implementation, a tether518may be introduced during a tether mode or test mode to check for thresholds, among other reasons. The tether518may be, without limitation, a snare, a flexible shaft, and/or the like. For example, the tether518may include an elongated body520extending distally through the lumen516of the retriever144to a distal loop522.

Turning toFIG. 24, another example of the docking cap136is shown. The body138of the docking cap136includes one or more cap surfaces, as described herein, adapted to provide torque to the leadless pacemaker104via the docking surfaces of the docking end of the leadless pacemaker104, as well as to move the first arm506and the second arm508to the engaged position around the docking projection148. In one implementation, the one or more cap surfaces are disposed relative to the chamber142and are adapted to matingly engage the docking surfaces and/or features of the retriever144. The one or more cap surfaces may include the distal end surface400, the proximal chamber surface402, and the side surface404extending between the proximal chamber surface402and the ledge surface406, which is disposed proximal to the distal end surface400within the chamber142. The distal end surface400defines an opening into the chamber132, and the proximal chamber surface402defines the proximal opening408into the chamber142extending through the receiving portion140. The proximal opening408is coaxial with the longitudinal axis of a lumen of the torque shaft114and/or the steerable catheter118and the lumen516of the retriever144.

The ledge surface406may mirror a size and shape of the surface302of the docking end of the body300of the leadless pacemaker104. For example, both the ledge surface406and the surface302may be flat. The mating engagement of each of the various cap surfaces with the corresponding docking surfaces provides torque transmission. To further facilitate torque transmission, one or more of the cap surfaces may include the cap keys410. In one implementation, the cap keys410are disposed radially around a distal side surface414extending from the ledge surface406towards the distal end surface400. The cap keys410may be adapted to matingly engage corresponding side keys310defined in the docking projection148for torque transmission.

Additional examples of the docking projection148are shown inFIGS. 25A-25B. In one implementation, the side keys310are defined in the edge docking surfaces306of the docking projection148extending from the surface302of the body300to the end surface308. The side keys310may be oriented relative to each other on opposite sides, such that they are radially symmetric. In one implementation, the cap136is adapted to matingly engage the docking projection148with the edge docking surfaces306disposed along the distal side surface414and the cap keys410disposed within the side keys310.

The ledge surface406may be adapted to displace the first arm506and the second arm508radially inward from their natural state in which they are biased radially outwards. In one implementation, the ledge surface406displaces the first and second arms506and508until they close around the docking button320in the engaged position shown inFIG. 21. The side surface404holds the first and second arms506and508around the docking button320with the first and second lips510and512extending inwardly past an outer edge of the docking button320, preventing the docking button320from translating distally out of the docking space514and thus releasing from the retriever144.

The docking button320may be mounted to the end surface308with the first and second posts316and318. As can be understood fromFIG. 25A-25B, the docking button320may be integral with, connected rigidly to, and/or connected flexibly to the posts316and318. In one implementation, the docking button320is a rounded surface extending between the first end322and the second end324, which are separated by a gap opening into a button lumen326. The docking button320includes a first slot328and a second slot330adapted to receive and engage the first and second posts316and318, respectively.

For a detailed description of docking and releasing the leadless pacemaker104for delivery and/or retrieval, reference is made toFIGS. 26A-26C. In one implementation, the retriever144is disposed relative to the docking projection148.FIG. 26Aillustrates the retriever144approaching the docking projection148for engagement. The docking projection148is positioned in the docking space514between the first and second arms506and508. For example, the docking button320of the docking projection148may be positioned within the docking space514, as shown inFIG. 26B. The body138of the docking cap136is sheathed over the retriever144until the docking end of the leadless pacemaker104including the docking projection148is disposed within the chamber142. The docking cap136holds the retriever144in compression around the docking button320locking the leadless pacemaker104in the docked position shown inFIG. 26C. The leadless pacemaker104is thus docked to the catheter system108and prepared for delivery through the patient anatomy to the implant site, for example, within the patient heart102. The engagement of the docking cap136with the docking end of the leadless pacemaker104may be strong enough to maintain the leadless pacemaker104in the docked position against the force of gravity.

Once disposed within the implant site, the catheter system108is rotated using the handle body122. The mating engagement of the one or more cap surfaces with the one or more docking surfaces transmits the torque of this rotation to the leadless pacemaker104to fix the leadless pacemaker104to the tissue at the implant site using the helical anchor106. In some implementations, the tether518is used to check for thresholds. Once the leadless pacemaker104is fixed in the implant site, the catheter system108releases the leadless pacemaker104. In one implementation, the body138of the docking cap136is retracted proximally until the retriever144is outside the chamber142, causing the first arm506and the second arm508to spring open in a direction radially outwardly, thereby releasing the docking button320. The catheter system108is then retracted along the patient anatomy and removed from the body.

During retrieval, the catheter system108is introduced into the body and advanced through the patient anatomy to the implant site until the retriever144is disposed relative to the docking projection148. The retriever144is advanced until the docking button320is positioned within the docking space514between the first and second arms506and508. The body138of the docking cap136is sheathed over the retriever144, locking the leadless pacemaker104to the catheter system108in the docked position, as described herein. The catheter system108is then rotated with the mating engagement of the docking projection148with the docking cap136transmitting the torque to the leadless pacemaker104to unfix the helical anchor106from the tissue. The retriever144or other features of the catheter system108, such as a cutting edge, may be used to remove any tissue overgrowth on the leadless pacemaker104. The leadless pacemaker104is maintained in the docked position and the catheter system108is retracted through the patient anatomy to retrieve the leadless pacemaker104.

For another example of a docking cap adapted to lock the retriever144in the engaged position around the docking projection148, reference is made toFIG. 27. In one implementation, the docking cap includes an elongated body524with a lumen526defined therein. A tether528, which may be a snare, cable, or other tether, extends through the lumen526of the elongated body526, as well as the lumen516of the retriever144. The tether528may be looped through the docking projection148and taken back to the handle body122of the catheter system108.

In one implementation, the docking projection148of the leadless pacemaker104includes the docking button320attached to the surface302of the body300of the leadless pacemaker104with the post316. The docking button320includes a flat distal surface from which a hook332extends. The tether528may be looped through the hook332.

To engage the retriever144in the docked position with the docking projection148, the elongated body524is translated distally over the first arm506and the second arm508locking the docking button320in the engaged position within the docking space514, as described herein. To release the leadless pacemaker104, the elongated body526is translated proximally until the first and second arm506and508spring radially outwards to the natural state, thereby disengaging the docking button320.

Turning toFIGS. 28 and 29, another example of the retriever144is shown. In one implementation, the retriever144includes a retriever base600from which a set of arms602, including a first arm disposed opposite a second arm around a central lumen604, extends. In one implementation, the set of arms602are disposed on and/or integral with a retriever shaft606extending through the retriever base600. The central lumen604extends through the retriever shaft606, the retriever base600, and through the set of arms602.

The set of arms602are biased radially inwards towards the central lumen604in a natural state. In one implementation, a mandrel608is translated within the central lumen604to move the set of arms602between an engaged and disengaged position with the docking projection148. More particularly, the docking projection148may include a docking surface opening334defined within a docking surface336extending from or otherwise part of the surface302of docking end of the body300of the leadless pacemaker104. The set of arms602include a first tab610and a second tab612each extending radially outwards from the central lumen604. In the disengaged or natural state, the set of arms602are biased radially inwards, such that the set of arms602may be advanced through the docking surface opening334. The mandrel608is advanced distally through the central lumen604pushing the set of arms602apart elastically, such that the first tab610and the second tab612are displaced radially outwards, thereby engaging the edges defining the docking surface opening334and locking the retriever144to the docking projection148.

To disengage the retriever144from the docking projection148to release the leadless pacemaker104, the mandrel608is retracted proximally within the central lumen604, causing the set of arms602to spring radially inwards to the natural state. The first and second tabs610and612thus disengage the edges defining the docking surface opening334, permitting the catheter system108to be retracted.

For a detailed description of examples of the retriever144in the form of a snare loop, reference is made toFIGS. 30A-40. Turning first toFIGS. 30A-30B, in one implementation, the body138of the docking cap136is fixed to a component of the catheter system108, such as the torque shaft114. The chamber142of the docking cap136is coaxial with a lumen of the catheter system108, including, for example, a lumen of the torque shaft114.

In one implementation, the retriever144includes a first sheath702and a second sheath704extending distally from the chamber142. The first and second sheaths702and704may extend through the chamber142proximally into the lumen of the catheter system108. The first and second sheaths702and704each translate longitudinally through the chamber142and the lumen of the torque shaft114.

A snare700extends distally from and is translatable within the first and second sheaths702and704. The snare700is configured to move between an engaged and disengaged position to releasably engage the docking projection148. The first and second sheaths702and704may be made from a variety of materials, including, but not limited to, steel, elastic cable tubes, braided or coiled Polytetrafluoroethylene (PTFE) impregnated polyimide tubes, and/or the like. The snare700may be made from a variety of flexible materials, such as Nitinol or other elastic materials.

Turning toFIGS. 31A and 31B, in one implementation, the snare700extends from and is translatable within a first snare lumen710of the first sheath702and a second snare lumen712of the second sheath704. The snare700moves between the engaged and disengaged positions within the first and second snare lumens710and712to capture and release the docking projection148of the leadless pacemaker104. In one implementation, the first sheath702includes a first end coil706, and the second sheath704includes a second end coil708. Radiopacity may be obtained by making the first and second end coils706and708radiopaque. Alternatively or additionally, a NiTi DFT composite wire combining Nitinol with Titanium or Platinum in varying sheath-to-core ratios, a Tungsten or Tantalum strand in NiTi cable, and/or the like may be used for radiopacity. Further, radiopaque coils and/or marker bands may be crimped or otherwise attached to the snare700, radiopaque coils may be wound around an NiTi core, and/or the like.

In one implementation, the snare700includes a first snare wire714and a second snare wire716. The first snare wire714extends from the first snare lumen710into the second snare lumen712forming a first snare loop pointing in a first direction, and the second snare wire716extends from the first snare lumen710into the second snare lumen712forming a second snare loop pointing in a second direction. In one implementation, the first direction is different from the second direction, forming a docking space therebetween. The first direction may be oriented relative to the second direction such that the snare700forms a duckbill shape.

As can be understood fromFIGS. 32-36, to engage the docking projection148and lock the leadless pacemaker104in the docked position with the catheter system108, the docking space formed by the snare700is disposed relative to at least a portion of the docking projection148, such as the docking button320, as shown inFIG. 32. The snare700is then advanced distally over the leadless pacemaker104until the docking projection148is disposed in the docking space. For example, the first snare loop and the second snare loop are advanced distally until the docking button320is disposed in the docking space of the snare700, as shown inFIG. 33A. The snare700may be advanced by advancing the catheter system308, the snare700, and/or the first and second sheaths702and704. The first and second sheaths702and704are translatable through the docking cap136, and the first snare wire714and the second snare wire716are each translatable within the first snare lumen710and the second snare lumen712.

The snare700is moveable from the disengaged position to the engaged position, shown inFIGS. 33B and 34, by translating the first snare wire714and the second snare wire716proximally within the first snare lumen710and the second snare lumen712. Stated differently, the first and second snare wires714and716are each retracted into the first and second snare lumens710and712. The proximal translation of the first and second snare wires714and716tightens the snare700, closing the first and second snare loops into smaller loops. Stated differently, a peak of each of the snare loops formed by the first snare wire714and the second snare wire716moves proximally towards a distal end of the first and second sheaths702and704decreasing a size of each of the snare loops. Additionally, the peaks of the snare loops formed by the first snare wire714and the second snare wire716simultaneously move towards each other and a central axis of the docking space during the proximal translation of the first and second snare wires714and716. The movement of the peaks radially inwards towards each other and the central axis decreases a size of the docking space and tightens the first and second snare wires714and716around at least a portion of the docking projection148, thereby locking the docking projection148in the engaged position. For example, as shown inFIGS. 33B and 34, the size of the docking space may be decreased until the first and second wires714and716close around the first and second posts316and318and/or the size of the docking space is smaller than a size of the docking button320.

The snare700captures and locks the docking projection148in the engaged position with a freedom of movement of the leadless pacemaker104. More particularly, as shown inFIG. 35, the engagement of the snare700with the docking projection148provides a junction that permits movement of the leadless pacemaker104relative to a longitudinal axis of extending through the chamber142and/or one or more lumens of the catheter system108. The movement may be parallel or at an angle to the longitudinal axis without releasing the leadless pacemaker104from the catheter system108. For example, as shown inFIG. 35, the junction may act like a hinge allowing the repositioning of the leadless pacemaker104without release.

Once the snare700is in the engaged position with the docking projection148, to move the leadless pacemaker104to the docked position with the catheter108, as shown inFIG. 36, the first sheath702and the second sheath704are retracted proximally until the docking projection148is disposed within the chamber142of the docking cap136. In the docked position, the leadless pacemaker104may be moved through the patient anatomy to and/or from the implant site. During retrieval, the snare700and/or other features of the retriever144may include a cutting edge or similar mechanism for removing tissue overgrowth on the leadless pacemaker104. Further, the retriever144may be used in a tether and/or test mode, for example, to test for thresholds by advancing the first and second sheaths702and704along with the first and second snare wires714and716, such that the docking projection148remains engaged with the snare700.

For a detailed description of the interaction of the retriever144with the docking cap136, reference is made toFIGS. 37-40. In one implementation, the body138of the docking cap136includes one or more cap surfaces, as described herein, adapted to provide torque to the leadless pacemaker104via the docking surfaces of the docking end of the leadless pacemaker104. In one implementation, the one or more cap surfaces are disposed relative to the chamber142and are adapted to matingly engage the docking surfaces and/or features of the retriever144. The one or more cap surfaces may include the distal end surface400, the proximal chamber surface402, and the side surface404extending between the proximal chamber surface402and the distal end surface400. The distal end surface400defines an opening into the chamber132, and the proximal chamber surface402defines the proximal opening408into the chamber142extending through the receiving portion140. The proximal opening408may be coaxial with the longitudinal axis of a lumen of the torque shaft114and/or the steerable catheter118and the central axis of the snare700.

The mating engagement of each of the various cap surfaces with the corresponding docking surfaces provides torque transmission. To further facilitate torque transmission, one or more of the cap surfaces may include the cap keys410. In one implementation, the cap keys410are disposed radially around the side surface404, for example, on radially opposite sides of the longitudinal axis. The cap keys410may be adapted to matingly engage corresponding side keys310defined in the docking projection148for torque transmission, as described herein.

In one implementation, the docking cap136further includes one or more trackers corresponding to the one or more sheaths of the retriever144. For example, the docking cap136may include a first tracker416corresponding to the first sheath702and a second tracker418corresponding to the second sheath704. In one implementation, the first and second trackers416and418maintain the first and second sheaths702and704in an orientation relative to each other and to the center axis coaxial with the longitudinal axis running through the proximal opening408. The orientation may include, for example, the first sheath702maintained in a position radially opposite the second sheath704about the center axis. Stated differently, the first and second sheaths702and704may be disposed approximately 180 degrees apart about the center axis.

The first and second sheaths702and704are translatable within the first and second trackers416and418, respectively. In one implementation, the first tracker416includes a first tracker lumen420within which the first sheath702is translatable, and the second tracker418includes a second tracker lumen422within which the second sheath704is translatable, as shown inFIGS. 38-40. The first and second trackers416and418thus maintain the first and second sheaths702and704in an orientation adapted to position the snare700for capturing the docking projection148such that it can be moved into the chamber142into the docking position by retracting the first and second sheaths702and704into the lumen of the torque shaft114.

In one implementation, the docking button320is mounted to the docking projection148with a set of docking balls fixed to the first and second posts316and318, as shown inFIGS. 39-40. The first post316may extend between a first proximal ball336and a first distal ball340. The first proximal ball336is disposed in the first slot328, and the first distal ball340extends through an opening in the end surface308, thereby mounting the docking button320to the docking projection148with the first post316. Similarly, the second post318may extend between a second proximal ball338and a second distal ball342. The second proximal ball338is disposed in the second slot330, and the second distal ball342extends through another opening in the end surface308, thereby mounting the docking button320to the docking projection148with the second post318. In one implementation, the first post316is mounted to the docking projection148and the docking button320such that it is radially symmetric with the second post318.

It will be appreciated that the retriever144may be displaced to engage the docking projection148using the docking cap136as described herein. Additionally or alternatively, a push-pull actuator826may be used to cause the retriever144to engage and disengage the docking projection148. For example, turning toFIGS. 41-46, in one implementation, the retriever144is in the form of a hinged grasper and displaceable between the engaged and disengaged position with a push-pull actuator826.

Referring first toFIGS. 41-43, in one implementation, the leadless pacemaker104includes the docking projection148extending from the surface302at the docking end of the body300. The docking projection148includes a projection800defining a slot802. In one implementation, the projection800has a length extending in a first direction across the surface302, such that the length is approximately the same as a diameter of the surface302, and the projection800has a narrow width extending in a second direction across the surface302, with the width being less than the diameter of the surface302.

The projection800includes one or more docking surfaces defining the slot802and configured to matingly engage corresponding features of the retriever144, thereby providing torque transmission to the leadless pacemaker104. In one implementation, the retriever144in the form a hinged grasper is formed with a first arm804and a second arm806. A first grasping portion808is disposed at a distal end of the first arm804and includes a first cutout812. Similarly, a second grasping portion810is disposed at a distal end of the second arm806and includes a second cutout814.

The first cutout812and the second cutout814collectively define a docking space816adapted to engage the projection800. More specifically, to engage the leadless pacemaker104in the engaged position, lips of the grasping portions808and810extend into the slot802with a proximal portion of the projection800disposed in the docking space816, thereby gripping the docking projection148with the retriever144. The first arm804and the second arm806move radially outwardly into the disengaged position and the grasping portions808and810release the projection800, widening the docking space816. In one implementation, the first arm804and the second arm806each taper in width proximally from the grasping portions808and810to a base818.

To move the arms804and806between the engaged and disengaged positions, the push-pull826actuator is translated relative to the docking cap136within the chamber142. The push-pull actuator826may extend through and be translated within a lumen of the torque shaft114. In one implementation, the push-pull actuator826includes a neck824extending distally from a body of the push-pull actuator826. The neck824includes one or more knobs822extending radially outwardly from a longitudinal axis of the push-pull actuator826. The neck824is disposed within a gap824defined in each of the first arm804and the second arm806, and each of the knobs engage corresponding tracks820in each of the arms804and806. One or more hinge pins828extend through holes in the docking cap136and the arms804and806to rotationally mount the retriever144to the docking cap136. Engagement of the knobs822with the arms804and806within the tracks820causes the push-pull actuator826to displace the arms804and806radially inwardly and outwardly relative to a rotational axis of the hinge pin(s)828when the body of the push-pull actuator826is translated distally and proximally.

Similarly, turning toFIGS. 44-46, the first arm804and the second arm806are displaceable between the engaged and disengaged position with the push-pull actuator826. In one implementation, the docking projection148includes one or more docking surfaces, including edge docking surfaces306and/or the like, configured to matingly engage corresponding features of the first arm804and the second arm806, thereby providing torque transmission to the leadless pacemaker104. The docking surfaces306may form a hexagonal shape or other polygonal shape of the docking projection148. The first arm804may include a first docking surface832, and the second arm806may include a second docking surface834. Each of the first and second docking surfaces832and834may be planar or other shapes mirroring a shape of the edge docking surfaces306.

The first docking surface832and the second docking surface834are adapted to engage one or more of the edge docking surfaces306of the docking projection148. More specifically, to engage the leadless pacemaker104in the engaged position, first docking surface832and the second docking surface834are pressed against the edge docking surfaces306, thereby gripping the docking projection148with the retriever144. The first arm804and the second arm806move radially outwardly into the disengaged position and the grasping portions808and810release the docking projection148.

The foregoing merely illustrates the principles of the presently disclosed technology. Various modifications and alterations to the described implementations will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements and methods which, although not explicitly shown or described herein, embody the principles of the presently disclosed technology and are thus within the spirit and scope of the present presently disclosed technology. From the above description and drawings, it will be understood by those of ordinary skill in the art that the particular implementations shown and described are for purposes of illustrations only and are not intended to limit the scope of the present presently disclosed technology. References to details of particular implementations are not intended to limit the scope of the presently disclosed technology.