EP4655062A1

EP4655062A1 - Delivery and retrieval system for a medical device

Info

Publication number: EP4655062A1
Application number: EP24701477.2A
Authority: EP
Inventors: Ronald A. Drake; Lester O. Stener
Original assignee: Medtronic Inc
Current assignee: Medtronic Inc
Priority date: 2023-01-24
Filing date: 2024-01-04
Publication date: 2025-12-03
Also published as: CN120569243A; WO2024157089A1

Abstract

A medical system configured to impart a torque to a medical device within a patient. The medical system includes a driver including a driver body defining a protracted portion. The medical system includes a snare configured to translate through a lumen defined by the driver engage the medical device. The protracted portion extends distally beyond an opening to the driver lumen. The driver is configured to substantially trap the snare loop between the protracted portion and the implantable medical device (e.g., a stem of a retrieval structure), such that a torque on the driver body causes the driver to impart a tensile force to the snare. The snare is configured such that the tensile force causes the snare to transfer some portion of the torque on the driver body to the implantable medical device to cause a rotation of the implantable medical device about a device axis.

Description

DELIVERY AND RETRIEVAL SYSTEM FOR A MEDICAL DEVICE

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/481,297, filed January 24, 2023, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] This disclosure is related to system for delivery and/or retrieval of implantable medical devices.

BACKGROUND

[0003] Various types of implantable medical devices have been implanted for treating or monitoring one or more conditions of a patient. Such implantable medical devices may be adapted to allow medical devices to monitor and/or treat conditions or functions relating to heart, muscle, nerve, brain, stomach, endocrine organs or other organs and their related functions. The implantable medical devices may be implanted at target locations selected to detect a physiological condition of the patient and/or deliver one or more therapies. For example, implantable medical devices may be delivered to locations within an atrium or ventricle of a heart to sense intrinsic cardiac signals and deliver pacing or antitachyarrhythmia shock therapy.

[0004] Some implantable medical devices are sized to be completely implanted within one of the chambers of the heart and/or another anatomical volume of the patient to detect a physiological condition and/or deliver one or more therapies. Such implantable medical devices may utilize delivery and/or retrieval systems to allow a clinician to navigate the implantable medical device (e.g., through vasculature of the patient) to the target location, and/or to retrieve the implantable medical device from the patient. In some examples, the implantable medical device may include one or more anchoring components intended to engage tissues at the target location (e.g., for implantation) and/or disengage from tissue at the target location (e.g., for retrieval).

SUMMARY

[0005] The disclosure describes a medical system configured to deliver, position, retrieve, and/or otherwise re-orient an implantable medical device (“IMD”) within an anatomical volume (e.g., a chamber of a heart) within a patient. The medical system includes a driver including a driver body defining a protracted portion supported substantially at a distal end of the driver body. The medical system further includes a snare configured to translate through a lumen defined by the driver body to engage the IMD. In examples, the snare is configured to engage the IMD when a snare loop of the snare substantially surrounds a perimeter of the IMD (e.g., a perimeter of a retrieval structure) and the snare loop constricts around the IMD (e.g., due to a proximal force on a distal portion of the snare). The driver is configured such that the protracted portion of the driver body extends distally beyond an opening to the lumen. The driver is configured to substantially trap the snare loop between the protracted portion and the IMD (e.g., a stem of a retrieval structure), such that a torque on the driver body causes the driver to impart a tensile force to the snare.

[0006] In examples, when the torque is placed on the driver body, contact between the protracted portion and the IMD causes a torque axis substantially extending through the protracted portion, such that the driver body pivots and/or attempts to pivot relative to the IMD. The torque around the torque axis of the protracted portion may cause an inner surface of the lumen through which the snare extends to exert a tensile force on the snare, increasing the frictional engagement of the snare loop around the perimeter of the IMD. The tensile force may cause the snare loop to exert a rotation torque around a device axis of the IMD, causing rotation of the IMD as the torque is imparted (e.g., by a clinician) to the driver body. In examples, the medical system includes a delivery catheter configured to deliver and/or retrieve the head section, the intermediate member, and/or the implantable medical device through vasculature of the patient.

[0007] In an example, a medical system comprises: a driver configured to impart a torque on an implantable medical device within an anatomical volume defined by a body of a patient, wherein a driver body of the driver defines a lumen extending to a lumen opening in a distal portion of the driver body and defines a longitudinal axis extending through the lumen, and wherein the driver body defines a protracted portion extending distal to the lumen opening; and a snare configured to slidably translate within the lumen and extend through the lumen opening, the snare defining a snare loop configured to surround a perimeter of the implantable medical device, wherein the protracted portion is configured to contact the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare extends through the lumen opening and the snare loop surrounds the perimeter of the implantable medical device, and wherein the driver is configured to impart a tensile force to the snare when the snare loop surrounds the perimeter of the implantable medical device, the protracted portion traps the snare loop, and a torque around the longitudinal axis is imparted to the driver body.

[0008] In an example, a technique comprises: surrounding, using a snare loop of a snare extending through a lumen opening of a driver body of a driver, a perimeter defined by an implantable medical device; contacting, using a protracted portion of the driver body, the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare loop surrounds the perimeter; imparting, using the driver, a torque on the driver body; and imparting, using the driver, a tensile force to the snare when the snare loop surrounds the perimeter of the implantable medical device, the protracted portion traps the snare loop, and the driver imparts the torque to the driver body.

[0009] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a conceptual diagram illustrating an example medical system and delivery catheter within a heart.

[0011] FIG. 2 is a perspective illustration of an example medical system including a driver and snare.

[0012] FIG. 3 is a perspective illustration of a protracted portion engaging an implantable medical device.

[0013] FIG. 4 is a schematic diagram of an example medical system including a driver, a protracted portion, and a snare shown in conjunction with an example implantable medical device.

[0014] FIG. 5 is a transverse cross-sectional diagram of the example medical system of FIG. 4.

[0015] FIG. 6 is a transverse cross-sectional diagram of the example medical system of FIG. 5 with a torque imparted to a driver body. [0016] FIG. 7 is a schematic diagram of an example protracted portion including a first leg and a second leg.

[0017] FIG. 8 is a schematic diagram of an example protracted portion including a bridging member.

[0018] FIG. 9 is a schematic diagram of an example protracted portion including a wall section defining a cavity.

[0019] FIG. 10 is a longitudinal cross-sectional diagram of an example medical system including a driver, a snare, and a delivery catheter shown in conjunction with an example implantable medical device.

[0020] FIG. 11 is a schematic illustration of a retrieval structure of an implantable medical device, transverse cross-sectional diagram of the example medical system of FIG. 5 with a head section in a first position relative to the implantable medical device.

[0021] FIG. 12 illustrates an example technique for transferring a torque to an implantable medical device.

DETAILED DESCRIPTION

[0022] This disclosure describes a medical system configured to deliver, position, and/or retrieve an implantable medical device (“IMD”) within an anatomical volume (e.g., a chamber of a heart) within a patient. The medical system is configured to receive a torque (e.g., from a clinician) and impart the torque to IMD to implant, retrieve, reposition, and/or re-orient the IMD in the anatomical volume. In examples, the medical system is configured to enable a rotation of the IMD around a device axis when the medical system imparts the torque. The rotation of the implantable medical device may cause an attachment member of the implantable medical device to engage tissues at a target site, disengage tissues at the target site, and/or otherwise cause a re-orientation of the medical device within the patient.

[0023] The medical system includes a driver configured to receive the torque (e.g., from the clinician) and impart the torque to the IMD. The medical system further includes a snare configured to extend through a lumen opening of a lumen of the driver (“driver lumen”). The snare includes a snare loop configured to surround a perimeter defined by the IMD (“IMD perimeter”), such as an IMD perimeter defined by a retrieval structure of the IMD. The driver includes a driver body (e.g., an elongate body) defining a protracted portion configured to extend distally beyond the lumen opening. The driver is configured such that, when the snare loop surrounds the IMD perimeter, the protracted portion contacts the IMD to substantially trap (e.g., position) the snare loop between the IMD and the protracted portion.

[0024] The driver is configured such that a torque imparted to the driver body (e.g., by a clinician) around a longitudinal axis of the driver transfers to the protracted portion, such that the protracted portion experiences a torque around the longitudinal axis. When the protracted portion establishes contact with the IMD and the torque transfers to the protracted portion, the driver body may pivot and/or attempt to pivot around a torque axis extending through the protracted portion, such that at least a distal portion of the driver body experiences the torque around the torque axis. When the snare extends through the driver lumen and the snare loop surrounds the IMD perimeter, the torque around the torque axis causes an inner surface of the driver lumen to exert a tensile force on the snare, substantially increasing the frictional engagement of the snare loop around the perimeter of the IMD. The tensile force may cause the snare loop to exert a rotation torque around a device axis of the IMD, causing rotation of the IMD as the torque is imparted (e.g., by a clinician) to the driver body.

[0025] For example, the driver may be configured such that the longitudinal axis of the driver extends through the driver lumen and the protracted portion is radially displaced from the longitudinal axis, such that a radial displacement is present between the protracted portion and a boundary of the opening to the driver lumen defined by an inner surface of the driver lumen (“lumen opening boundary”). The snare may be configured to contact the lumen opening boundary when snare extends through the driver lumen and the snare loop constricts around the IMD perimeter. Hence, when the driver body contacts the IMD and a torque causes the driver body to pivot or attempt to pivot around the contact point between the protracted portion and the IMD, the radial displacement between the protracted portion and the lumen opening boundary causes the lumen opening boundary to experience a torque around the contact point. The torque around the contact point experienced by the lumen opening boundary may cause the lumen opening boundary to exert a force (e.g., an action force) on the snare loop, causing the IMD to exert an opposing force (e.g., a reaction force) on the snare loop, such that the lumen opening boundary imparts a tensile force to the snare. The tensile force may increase the frictional engagement of the snare loop around the perimeter of the IMD while increasing a torque on the snare loop around the device axis, such that the snare loop may cause rotation of the IMD.

[0026] The protracted portion is configured to trap (e.g., maintain a position of ) the snare (e.g., the snare loop) between the IMD perimeter and the protracted portion when the snare loop surrounds the IMD perimeter and the protracted portion contacts the IMD. The protracted portion may be configured to trap the snare such that the snare contacts the protracted portion as the snare extends from the IMD perimeter to the lumen opening of the driver body. The protracted portion may act to trap the snare to substantially maintain the contact between the snare and the protracted portion, such that when the driver body pivots or attempts to pivot around the torque axis of the protracted portion, the trapping by the protrusion portion causes the snare to extend around some portion of the protrusion portion as the snare extends from the IMD perimeter to the lumen opening of the driver body.

[0027] In examples, the protracted portion is configured to guide the snare from the IMD perimeter to the lumen opening of the driver body when the snare surrounds the IMD perimeter, the protracted portion traps the snare, and a torque imparted to the driver body causes an inner surface of the driver lumen (e.g., the lumen opening boundary) to impart a tensile force on the snare. The protracted portion may be configured to substantially maintain the snare between the protracted portion and the IMD perimeter as the snare experiences the tensile force rather than, for example, allowing the tensile force to cause the snare to slip around the protracted portion and extend from the IMD perimeter to the lumen opening without contacting the protracted portion. For example, the protracted portion may be configured to redirect a path of the snare from the IMD perimeter to the lumen opening when the driver body pivots or attempts to pivot around the contact point of the protracted portion relative to the IMD.

[0028] In examples, the driver is configured such that a torque on the driver body increases a tensile force on the snare caused initially by, for example, a proximal force imparted to the snare (e.g., by a clinician). For example, the snare may be configured to translate through the driver lumen and substantially tighten (e.g., constrict) around the IMD perimeter when the snare loop surrounds the IMD perimeter and a proximal force is exerted on a distal portion of the snare (e.g., by a clinician). The driver body may be configured such that when the protracted portion contacts the IMD and the snare loop surrounds the IMD perimeter, the driver body (e.g., a boundary of the lumen opening), substantially redirects the proximal force to generate a first tension on the snare in a direction oblique to (e.g., substantially perpendicular to) the device axis of the IMD. This first tension may generate some degree of frictional engagement between the snare loop and the portion of the IMD defining the IMD perimeter. In examples, the driver body is configured to translate substantially over the snare as the snare extends through the driver lumen, such that the snare substantially guides the protracted portion toward and/or into contact with the IMD to trap the snare loop between the IMD and the protracted portion. [0029] The driver may be configured such that, when the torque is imparted to the driver body (e.g., by the clinician) and the protracted portion contacts the IMD, the torque on the driver body causes the inner surface of the driver lumen (e.g., the lumen opening boundary) to impart a second tensile force on the snare which is additive to the first tensile force on the snare. Hence, the driver may be configured to substantially increase the tensile force on the snare over that which might result solely from a proximal force applied to a distal portion of the snare. The driver may be configured to substantially combine the proximal force on the snare and the torque on the driver body to generate the tensile force on the snare, such that, for example, a degree of proximal force necessary to generate a satisfactory frictional engagement between the snare loop and the IMD may be reduced by imparting a torque on the driver body.

[0030] In examples, the snare loop is configured to surround a perimeter defined by a retrieval structure of the IMD. For example, the retrieval structure may be coupled (e.g., attached to) a proximal portion of the IMD. The protrusion portion may be configured to trap the snare loop between the protrusion portion and the retrieval structure. In some examples, the snare may be configured to surround a neck portion of the retrieval structure. The neck portion may define a reduced radius with respect to a device axis compared to, for example, a body of the IMD (“IMD body”) and/or another portion of the IMD structure, such that the neck portion defines a recess. In examples, the protrusion portion may be configured to substantially span the recess when the protrusion portion traps the snare loop.

[0031] In some examples, the protracted portion includes a first leg and a second leg, with each of the first leg and the second leg extending distally beyond the lumen opening. The first leg may be configured to contact the IMD to trap the snare loop when a torque is imparted to the driver body in a first rotational direction. The second leg may be configured to contact the IMD to trap the snare loop when a torque is imparted to the driver body in a second rotational direction opposite the first rotational direction. In some examples, the protracted portion includes a bridging member extending substantially from a distal portion of the first leg to a distal portion of the second leg. In some examples, the protracted portion includes a wall section extending between the first leg and the second leg and defining a cavity having a cavity opening. The lumen opening of the driver lumen may open into the cavity, such that the snare may slidably translate within the driver lumen to extend through the lumen opening, the cavity, and the cavity opening. The bridging member and/or the wall section may be configured to contact the IMD to, for example, assist the protracted portion to span a recess formed by a neck portion of a retrieval structure.

[0032] The driver may be configured such that, when the protracted portion contacts the IMD and a torque on the driver body acts to increase the tensile force on the snare, the driver body, the snare loop, and the IMD lock into substantially stationary relative positions, such that a continued torque exerted on the driver body causes the snare loop to transfer at least some portion of the torque to the IMD to cause rotation of the IMD. Stated similarly, when the driver body, the snare loop, and the IMD lock into substantially the stationary relative positions and continued torque on the driver body continues to cause the rotation of the driver body about the longitudinal axis of the driver body, the longitudinal axis may begin to substantially orbit around the device axis of the IMD to accommodate the continued rotation of the driver body. With the driver body, the snare loop, and the IMD locked into substantially stationary relative positions, the orbiting of the longitudinal axis around the device axis causes the snare to impart at least some portion of the torque to the IMD, causing rotation of the IMD about the device axis. In examples, the IMD includes an attachment member (e.g., a helix) configured to engage tissue or disengage from tissue based on the rotation of the IMD. The rotation of the IMD about the device axis may cause the attachment member of the implantable medical device to engage tissues at a target site, disengage tissues at the target site, and/or otherwise cause a reorientation of the medical device within the patient.

[0033] In examples, the medical system includes a delivery catheter including a delivery receptacle. The delivery receptacle may define a delivery receptacle volume configured to receive the driver body, the snare, and/or at least a portion of the IMD. The delivery catheter may define a delivery catheter lumen and a delivery lumen opening which opens to the delivery receptacle volume. The driver may be configured to slidably translate within the delivery catheter lumen and through the delivery lumen opening, such that relative movement between the driver and the delivery catheter may cause the driver body, the snare, and/or at least the portion of the IMD to position within the delivery receptacle volume and/or exit the delivery receptacle volume (via the delivery lumen opening). The delivery catheter may be configured to transition through the vasculature of a patient, such that the driver, the snare, and/or the IMD may be retrieved from and/or delivered to an anatomical volume of the patient (e.g., a heart chamber).

[0034] FIG. 1 is a conceptual diagram illustrating an example medical system 100 within a right atrium (“RA”) of a heart 101. Medical system 100 includes driver 102 including driver body 104. Driver body 104 may include a distal portion 105 (“driver body distal portion 105”) configured to be intracorporeal to the patient and a proximal portion 107 (“driver body proximal portion 107”) which may be extracorporeal to the patient when driver body distal portion 105 is intracorporeal. A protracted portion 106 is supported at driver body distal portion 105. In examples, protracted portion 106 defines a distal end of driver body 104. In some examples, protracted portion 106 and driver body 104 may be substantially separate components. In some examples, protracted portion 106 may be substantially contiguous with driver body 104, such that protracted portion 106 and driver body 104 define a unified component.

[0035] Medical system 100 is configured to transfer a torque to an IMD 110 within an anatomical volume of a patient, such as the RA of heart 101. In examples, medical system 100 is configured to engage a proximal portion 114 of IMD 110 (“IMD proximal portion 114”) to transfer the torque. In examples, IMD proximal portion 114 includes a retrieval structure 111 (“IMD retrieval structure 111”). IMD retrieval structure 111 may be configured to engage with medical system 100 and/or another medical device to, for example, implant IMD 110 within an anatomical volume, retrieve IMD 110 from an anatomical volume, re -position IMD 110 within an anatomical volume, and/or re-orient IMD 110 within an anatomical volume. IMD 110 may include a distal portion 116 (“IMD distal portion 116”) opposite IMD proximal portion 114. [0036] In examples, IMD 110 (e.g., IMD distal portion 116) supports an attachment member 118 configured to engage tissue within a target site 120 of an anatomical volume. Attachment member 118 may be supported in IMD distal portion 116. In some examples, attachment member 118 is configured (e.g., as a helix) such that rotation of IMD 110 about a device axis LD defined by IMD 110 causes attachment member 118 to engage and/or disengage tissues with target site 120. For example, attachment member 118 may be configured such that rotation of IMD 110 in a first rotational direction W1 about device axis LD causes attachment member 118 to engage (or alternately, disengage from) tissues within target site 120. Attachment member 118 may be configured such that rotation of IMD 110 about device axis LD in a second rotational direction W2 substantially opposite first rotational direction W1 causes attachment member 118 to disengage from (or alternately, engage) tissues within target site 120. In examples, IMD 110 includes one or more components (e.g., a communication antenna, a sensor, or another component) configured to rotate around and or revolve about device axis LD when IMD 110 rotates about device axis LD. Medical system 100 may cause IMD 110 to rotate about device axis LD to cause one or more of the components to substantially establish a specific orientation with respect to the anatomy of the patient, another device implanted within or worn by the patient, another device external to the patient, and/or other devices.

[0037] Driver 102 (e.g., driver body 104) is configured to receive a torque (e.g., from a clinician) and transfer the torque to IMD 110. Driver body 104 may be configured to cause rotation of IMD 110 about device axis LD when driver body transfers the torque. Medical system 100 further includes a snare 122 including a body 124 (“snare body 124”) and a loop 126 (“snare loop 126”) at a distal end of snare body 124. Snare loop 126 is configured to engage IMD 110 (e.g., IMD retrieval structure 111) to, for example, surround and/or constrict around a perimeter of IMD 110 (“IMD perimeter”). In examples, snare loop 126 is configured to constrict around the IMD perimeter when snare loop 126 surrounds the IMD perimeter and a proximal force (e.g., a force in the direction P) is imparted (e.g., by a clinician) on snare 122. For example, snare loop 126 may be configured to constrict around the IMD perimeter when the proximal force is imparted to a distal portion 121 of snare 122 (“snare distal portion 121”). Snare distal portion 121 may be configured to be intracorporeal to the patient (e.g., via driver lumen 128). Snare 122 may define a proximal portion 123 (“snare proximal portion 123”), which may be extracorporeal to the patient when snare distal portion 121 is intracorporeal.

[0038] In examples, snare 122 is configured to substantially guide protracted portion 106 toward IMD 110 (e.g., IMD retrieval structure 111) and/or control a contact force between protracted portion 106 and IMD 110 (e.g., IMD retrieval structure 111). Driver body 104 defines a lumen 128 (“driver lumen 128”) and a lumen opening (“driver lumen opening 125”) in a driver body distal portion 105. Snare 122 may be configured to slidably translate within driver lumen 128, such that a clinician may cause snare 122 to translate proximally (e.g., in the direction P) and/or distally (e.g., in the direction D) within driver lumen 128, and/or cause driver 102 and protracted portion 106 to translate proximally and/or distally relative to snare 122. For example, snare 122 may be configured to extend through driver lumen 128 and distal to driver lumen opening 125 and/or protracted portion 106 to engage IMD 110. A clinician may cause driver 102 and protracted portion 106 to translate distally over snare 122 (e.g., over snare body 124 and/or snare loop 126) when snare loop 126 is engaged with IMD 110, such that snare 122 substantially guides protracted portion 106 toward IMD retrieval structure 111.

[0039] Protracted portion 106 is configured to extend distally beyond driver lumen opening 125. Driver 102 is configured such that, when snare loop 126 surrounds the IMD perimeter, protracted portion 106 substantially traps (e.g., maintains a position of) snare loop 126 between IMD 110 (e.g., IMD retrieval structure 111) and protracted portion 106. In examples, protracted portion 106 is configured to contact IMD 110 as a proximal force on snare body 124 causes snare loop 126 to constrict around and/or frictionally engage IMD 110. Protracted portion 106 may be configured such that snare 122 is positioned between protracted portion 106 and IMD 110 when snare 122 extends from driver lumen opening 125 and surrounds the IMD perimeter of IMD 110.

[0040] Driver 102 is configured such that a torque imparted to driver body 104 (e.g., by a clinician) around a longitudinal axis of driver body 104 transfers to protracted portion 106, such that protracted portion 106 experiences a torque around the longitudinal axis. When protracted portion 106 establishes contact with IMD 110 and the torque transfers to protracted portion 106, driver body 104 may pivot and/or attempt to pivot around a torque axis extending through protracted portion 106. For example, driver body 104 and/or protracted portion 106 may pivot and/or attempt to pivot around a contact point between protracted portion 106 and IMD 110. The pivoting and/or attempted pivoting of driver body 104 and/or protracted portion 106 may cause a lumen opening boundary defining driver lumen opening 125 to experience a torque around the contact point. When snare 122 extends through driver lumen 128 and snare loop 126 surrounds the IMD perimeter, the torque around the contact point experienced by the lumen opening boundary may cause the lumen opening boundary to exert a tensile force to snare 122. The tensile force may increase the frictional engagement of snare loop 126 with IMD 110, such that snare loop 126 transfers at some portion of the torque on driver body 104 to IMD 110 to cause rotation of IMD 110.

[0041] Medical system 100 may include a delivery catheter 134 configured to retrieve protracted portion 106, snare 122, and/or IMD 110 from an anatomical volume of the patient (e.g., the RA). In examples, delivery catheter 134 is configured to deliver protracted portion 106, snare 122, and/or IMD 110 to an anatomical volume of the patient. Delivery catheter 134 is illustrated as transparent in FIG. 1 for clarity. Delivery catheter 134 may include a distal portion 136 (“delivery catheter distal portion 136”) configured to be intracorporeal to the patient and a proximal portion 138 (“delivery catheter proximal portion 138”) which may be extracorporeal to the patient when delivery catheter distal portion 136 is intracorporeal. In examples, delivery catheter 134 is configured to deliver and/or retrieve protracted portion 106, driver body 104, and/or IMD 110 using vasculature of a patient, such as an IVC or other vasculature leading to the anatomical volume.

[0042] In examples, delivery catheter 134 includes a delivery receptacle 140 or receptacle defining a delivery receptacle volume (e.g., delivery receptacle volume 142 (FIG. 10)) configured to receive protracted portion 106, snare 122, and at least a portion of IMD 110. Delivery catheter 134 may define a lumen 144 (“delivery catheter lumen 144”) and a delivery lumen opening (e.g., delivery lumen opening 146 (FIG. 10)) which opens to delivery receptacle volume 142. At least driver body 104 may be configured to slidably translate within delivery catheter lumen 144 and through the delivery lumen opening such that relative movement between driver body 104 and delivery catheter 134 may cause relative movement between protracted portion 106 and/or IMD 110 and delivery catheter 134. Delivery receptacle 140 may define an opening (e.g., delivery receptacle opening 148 (FIG. 10)) at a distal end of delivery receptacle 140 (e.g., delivery receptacle distal end 150 (FIG. 10)). The delivery receptacle opening may be configured such that protracted portion 106, snare 122, and at least a portion of IMD 110 may pass therethrough.

[0043] Delivery catheter 134 may be configured to retrieve IMD 110 when IMD 110 is anchored to tissues within target site 120 (e.g., anchored by attachment member 118). For example, delivery catheter 134 may be configured to transition through vasculature of a patient to position protracted portion 106 and snare 122 in the proximity of IMD 110 when IMD 110 is anchored to tissues within target site 120. Delivery catheter 134 may be configured such that a force in the distal direction D on snare 122 (e.g., by a clinician) causes snare 122 to extend distal to the delivery receptacle opening of delivery receptacle 140, such that snare 122 (e.g., snare loop 126) may engage IMD 110. Delivery catheter 134 may be configured such that a force in the distal direction D on driver body 104 (e.g., exerted by a clinician) causes protracted portion 106 to extend distal to the delivery receptacle opening of delivery receptacle 140, such that driver body 104 may translate over snare 122 to position protracted portion 106 such that protracted portion substantially traps snare 122 (e.g., snare loop 126) between protracted portion 106 and IMD 110 (e.g., IMD retrieval structure 111). Delivery catheter 134 (e.g., delivery receptacle 140) may be configured to receive protracted portion 106, snare 122, and a portion of IMD 110 when protracted portion substantially traps snare 122 between protracted portion 106 and IMD 110. For example, delivery catheter 134 may move in the distal direction D relative to protracted portion 106, snare 122, and IMD 110 to receive protracted portion 106, snare 122, and at least the portion of IMD 110. Delivery catheter 134 may be configured to remove protracted portion 106, snare 122, and IMD 110 from an anatomical volume of the patient (e.g., the RA) after, for example, driver 102 has imparted a torque to IMD 110 causing attachment member 118 to disengage from tissues within target site 120. Delivery catheter 134, protracted portion 106, snare 122, and IMD 110 may subsequently be withdrawn from the patient (e.g., via vasculature of the patient).

[0044] In examples, delivery catheter 134 is configured to position IMD 110 in proximity to target site 120 such that IMD 110 may be anchored to tissues within target site 120 (e.g., anchored by attachment member 118). For example, delivery catheter 134 may be configured to position protracted portion 106 and snare 122 within delivery receptacle volume 142 when protracted portion 106 is positioned between snare 122 and IMD 110. Delivery catheter 134 may be configured to traverse vasculature of the patient to position IMD 110 (e.g., attachment member 118) within or in proximity to target site 120. Medical system 100 (e.g., driver body 104, protracted portion 106, and/or snare 122) may impart a torque to IMD 110 to cause attachment member 118 to engage tissues (e.g., tissue within target site 120) when attachment member 118 is within or in proximity to target site 120. Medical system 100 may be configured such that protracted portion 106 and/or snare 122 may be disengaged from IMD 110 as IMD 110 remains anchored to tissues within or in proximity to target site 120. Delivery catheter 134, protracted portion 106, and/or snare 122 may subsequently be withdrawn from the patient (e.g., via vasculature of the patient).

[0045] Although the examples herein discuss delivery, retrieval, and/or positioning of IMD 110 within the RA of heart 101, medical system 100 may be configured to position IMD 110 in any of the other chambers of heart 101 and/or in other anatomical volumes of a patient in a like manner as that described for the RA of heart 101. Further, although the examples herein discuss attachment member 118 defining a helix, attachment member 118 may define other structures, such as one or more elongated tines extending from, for example, IMD distal portion 116. Target site 120 may include an appendage of the RA, or the triangle of Koch region of the RA, or some other portion of heart 101, or some other location within a body of a patient.

[0046] FIG. 2 and FIG. 3 provide perspective views of a portion of medical system 100 with driver body 104 defining protracted portion 106. Driver body 104 defines a longitudinal axis L extending through driver lumen 128 and driver lumen opening 125. Snare 122 extends through driver lumen 128 and driver lumen opening 125. In FIG. 2 and FIG. 3, snare loop 126 is depicted surrounding an IMD perimeter PR defined by IMD 110 (e.g., IMD retrieval structure 111). Driver lumen 128, driver lumen opening 125, and snare body 124 are hidden by driver body 104 and illustrated with dashed lines in FIG. 2 and FIG. 3. In examples, IMD perimeter PR surrounds device axis LD defined by IMD 110. In examples, device axis LD extends through an area defined by and/or bounded by IMD perimeter PR

[0047] Snare 122 is configured such that snare loop 126 may constrict around IMD perimeter PR when a force in the proximal direction P is imparted (e.g., by a clinician) on snare body 124. Protracted portion 106 extends distal to driver lumen opening 125 to trap snare loop 126 between IMD 110 and protracted portion 106 when snare loop 126 surrounds IMD perimeter PR. Protracted portion 106 is configured to establish and/or substantially maintain contact with IMD 110 (e.g., IMD retrieval structure 111) when protracted portion 106 traps snare loop 126 substantially between protracted portion 106 and IMD perimeter PR. For example, protracted portion 106 may be configured to establish and/or substantially maintain contact with IMD 110 over an area including a contact point P (FIG. 3) when protracted portion 106 traps snare loop 126.

[0048] Protracted portion 106 is configured such that a torque T1 on driver body 104 and/or the around longitudinal axis L causes driver body 104 to pivot or attempt to pivot around contact point P. Protracted portion 106 is configured such that the pivoting or attempted pivoting around contact point P causes a torque on a lumen opening boundary (e.g., lumen opening boundary 156 (FIGS. 3-8)), such that the lumen opening boundary exerts a tensile force on snare 122. In examples, protracted portion 106 is configured to substantially guide snare 122 from IMD perimeter PR to driver lumen opening 125 when snare loop 126 surrounds IMD perimeter PR, protracted portion 106 traps snare 122 between protracted portion 106 and IMD 110, and torque T1 (e.g., around longitudinal axis L) imparted to driver body 104 causes the lumen opening boundary to impart a tensile force on snare 122. In examples, when snare loop 126 surrounds IMP perimeter PR, a proximal force FS on snare 122 causes a first tensile force on snare 122, and torque T1 is imparted to driver body 104 causes the lumen opening boundary to impart a second tensile force on snare 122 additive to the first tensile force. Hence, driver 102 may be configured such that torque T1 on driver body 104 (e.g., imparted by a clinician) increases a tensile force on snare 122 over that which might result solely from the proximal force FS applied (e.g., by the clinician) to snare 122.

[0049] Medical system 100 is configured such that torque T1 may cause a rotation of IMD 110 about device axis LD when snare loop 126 surrounds IMP perimeter PR. For example, medical system 100 may be configured such that, when torque T1 causes an increased tensile force on snare 122, the increased tensile force may increase in a contact force imparted by protracted portion 106 on IMD 110 (e.g., via contact point P) and/or increased frictional engagement of snare loop 126 with IMD perimeter PR. The increased contact force between protracted portion 106 and/or the increased frictional engagement between snare loop 126 and IMD perimeter PR may cause protracted portion 106 and IMD 110 to remain substantially stationary with respect to each other as the torque T1 imparts to driver body 104. When protracted portion 106 and IMD 110 maintain substantially stationary relative positions and torque T1 continues to cause the rotation of protracted portion 106 about longitudinal axis L, this may cause longitudinal axis L to substantially orbit around device axis LD of IMD 110 to accommodate the continued rotation of protracted portion 106. With protracted portion 106 and IMD 110 maintaining substantially stationary relative positions, the orbiting of longitudinal axis L around device axis LD may cause driver body 104 to impart at least some portion of torque T1 to IMD 110 via snare loop 126, causing rotation of IMD 110 about device axis LD. For example, the orbiting of longitudinal axis L around device axis LD as torque T1 is applied to driver body 104 may cause IMD 110 to rotate about device axis LD in the first rotational direction W1 or the second rotational direction W2 (FIG. 1).

[0050] As an example, FIG. 4 provides a schematic illustration of a portion of medical system 100 with snare 122 extending through driver lumen 128 and driver lumen opening 125 to surround IMD perimeter PR. Driver lumen 128, driver lumen opening 125, and snare body 124 are hidden by driver body 104 and illustrated with dashed lines in FIG. 4. IMD perimeter PR surrounds device axis LD in FIG. 4. FIG. 5 illustrates a cross-sectional view of driver 102 and snare 122 taken over and viewed in the direction of the cutting plane indicated as A-A’ in FIG. 4. FIG. 6 illustrates the cross-sectional view of FIG. 5 with torque T1 placed on driver body 104, causing protracted portion 106 to establish and/or substantially maintain contact with IMD 110 (e.g., IMD retrieval structure 111) at contact point P on IMD perimeter PR. In FIG. 5 and FIG. 6, the proximal direction P proceeds into the page and the distal direction D proceeds out of the page.

[0051] Although discussed below mainly with reference to contact between protracted portion 106 and IMD retrieval structure 111, protracted portion 106 may be configured to establish and/or substantially maintain contact with IMD 110 at any portion of IMD 110. For example, protracted portion 106 may be configured to establish and/or substantially maintain a contact point Pl with IMD 110 within a first area Al (FIG. 4) defined by a surface of IMD retrieval structure 111. Alternately or in addition to the establishing and/or substantially maintaining contact point Pl, protracted portion 106 may be configured to establish and/or substantially maintain a contact point P2 within a second area A2 (FIG. 4) defined by a surface of IMD proximal portion 114. Contact point P may be defined by contact point Pl, contact point P2, and/or any another contact point between protracted portion 106 and IMD 110. Protracted portion 106 may be configured to establish and/or substantially maintain contact point P in one of first area Al, second area A2, or another portion of IMD 110 while concurrently remaining in contact with any other of first area Al, second area A2, or the other portion of IMD 110.

[0052] Snare 122 may be configured to substantially guide driver 102 to a position adjacent to and/or contacting IMD 110, such that driver 102 establishes a position relative to IMD 110 substantially similar to that depicted in FIG. 4 and FIG. 5. For example, when snare 122 extends through driver lumen 128 and snare loop 126 surrounds IMD perimeter PR, driver 102 be translated (e.g., by a clinician) in the distal direction D towards IMD 110 as snare loop 126 surrounds IMD perimeter PR. In examples, snare 122 (e.g., snare loop 126) is configured to constrict around IMD perimeter PR when force FS is imparted to snare 122 in the proximal direction P (e.g., imparted by a clinician via, for example, snare proximal portion 123 (FIG. 1)). The constriction of snare loop 126 around IMD perimeter PR may increase a frictional engagement between a surface of snare loop 126 and a surface of IMD 110 defining IMD perimeter PR. Driver 102 translate relative to snare 122 (e.g., snare body 124 and/or snare loop 126) in the distal direction D and/or in the proximal direction P when snare loop 126 surrounds and/or constrict around IMD perimeter PR.

[0053] FIG. 6 illustrates driver body 104 experiencing torque T1 around longitudinal axis L as snare 122 extends through driver lumen opening 125 and snare loop 126 surrounds IMD perimeter PR. Driver 102 is configured such that torque T1 may cause a rotation of driver body 104 relative to IMD 110 until, for example, protracted portion 106 establishes contact with IMD 110. In examples, protracted portion 106 is configured to establish and/or substantially maintain contact with IMD 110 when torque T1 is imparted (e.g., by a clinician) to driver body 104. In examples, protracted portion 106 is configured to establish and/or substantially maintain contact with IMD 110 over a contact area (e.g., first area Al, second area A2, or another area of IMD 110) which includes contact point P. [0054] Driver body 104 may be configured such that, when protracted portion 106 establishes and/or substantially maintains contact with IMD 110, torque T1 causes driver body 104 to pivot and/or attempt to pivot around contact point P. For example, driver 102 may be configured to transfer at least a portion of torque T1 to protracted portion 106. Driver body 104 may be configured such that, when protracted portion 106 establishes and/or substantially maintains contact with IMD 110, torque T1 causes driver body 104 to rotate and/or attempt to rotate (e.g., relative to IMD 110) pivot around a torque axis TA extending through and defined by protracted portion 106, such that at driver body 104 (e.g. at least driver body distal portion 105) experiences the portion of torque T1 as a torque around torque axis TA. The torque around torque axis TA (e.g., driven by Torque T1 on driver body 104) may cause driver body 104 to pivot or attempt to pivot around contact point P. The pivoting and/or attempted pivoting of driver body 104 may cause driver body 104 and/or portions thereof to impart a tensile force to snare 122 when snare loop 126 surrounds (e.g., constricts around) IMD perimeter PR. Driver 102 may be configured to exert the tensile force snare 122 when a torque is imparted to driver body 104 in the first rotational direction W1 or the second rotational direction W2 (FIG. 1).

[0055] For example, driver body 104 may include an inner surface 154 defining driver lumen 128 (“driver lumen inner surface 154”) and/or a boundary 156 defining driver lumen opening 125 (“lumen opening boundary 156”). Snare 122 (e.g., snare body 124 and/or snare loop 126) may be configured to contact lumen opening boundary 156 and/or driver lumen inner surface 154 when snare 122 extends through driver lumen 128 and snare loop 122 surrounds IMD perimeter PR. Driver 102 may be configured such that the torque around torque axis TA causes lumen opening boundary 156 and/or lumen inner surface 154 to exert a tensile force on snare 122, substantially increasing a frictional engagement of snare loop 126 around IMD perimeter PR. The tensile force may cause snare loop 126 to exert a rotation torque TR about device axis LD on IMD 110, causing rotation IMD 110 as torque T1 is imparted (e.g., by a clinician) to driver body 104. Snare 122 (e.g., snare body 124 and/or snare loop 126) may be configured to contact lumen opening boundary 156 and/or lumen inner surface 154 snare 122 extends through driver lumen 128 and snare loop 122 surrounds (e.g., constricts around) IMD perimeter PR.

[0056] In examples, driver 102 is configured such that protracted portion 106 is radially displaced from longitudinal axis L, such that lumen opening boundary 156 and driver lumen inner surface 154 experience a torque around torque axis TA when driver body 104 pivots or attempts to pivot around contact point P. For example, driver 102 (e.g., driver body 104) may be configured to define a radial displacement RD between torque axis TA and lumen opening boundary 156 and/or lumen inner surface 154. Driver 102 may be configured such that, when torque T1 causes driver body 104 to pivot or attempt to pivot around contact point P, the resulting torque on lumen opening boundary 156 and driver lumen inner surface 154 around torque axis TA causes lumen opening boundary 156 and/or driver lumen inner surface 154 to exert a force (e.g., a force Fl) on snare 122. Lumen opening boundary 156 and/or driver lumen inner surface 154 may exert the force Fl in a direction substantially away from IMD 110 when torque T1 is imparted to driver body 104. The force Fl may cause IMD 110 (e.g., IMD perimeter PR) to exert an opposing force F2 on snare loop 126, increasing a tensile force in snare 122. The tensile force may increase the frictional engagement of snare loop 122 with IMD perimeter PR, such that when torque T1 causes longitudinal axis L to substantially orbit around device axis LD, snare loop 126 generates a sufficient rotation torque TR to cause rotation of IMD 110 about device axis LD.

[0057] Protracted portion 106 is configured to trap snare 122 (e.g., snare loop 126) substantially between IMD perimeter PR and protracted portion 106 when snare loop 126 surrounds IMD perimeter PR and protracted portion 106 contacts IMD 110. Protracted portion 106 may be configured to contact snare 122 (e.g., at snare contact point PS) as snare 122 extends from IMD perimeter PR to lumen opening boundary 156. Protracted portion 106 may trap snare 122 to substantially maintain contact with snare 122 (e.g., at snare contact point PS), such that when driver body 104 pivots or attempts to pivot around torque axis TA, protracted portion 106 constrains snare 122 to extend around some portion of protracted portion 106. In examples, protracted portion 106 is configured to exert a force (e.g., a force F3) on snare 122 as torque T1 imparts to driver body 104 and protracted portion 106 traps snare 122 between IMD perimeter PR and protracted portion 106. The force F3 may act to increases the tensile force in snare 122.

[0058] In examples, a location of contact point P relative to protracted portion 106 and/or IMD 110 may vary as torque TI is imparted to driver body 104. For example, contact point P may be a portion of (e.g., a point on) a surface defined by an outer perimeter PO of IMD 110 (e.g., IMD retrieval structure 111). Protracted portion 106 may be configured to contact outer perimeter PO to establish and/or substantially maintain contact with IMD 110. The location of contact point P on outer perimeter PO may vary as protracted portion 106 contacts outer perimeter PO to establish and/or substantially maintain contact with IMD 110. For example, as torque Tl imparts to driver body 104, protracted portion 106 may substantially alternate between slipping over outer perimeter PO, such that protracted portion 106 moves relative to IMD 110, and substantially gripping outer perimeter PO, such that protracted portion 106 is substantially stationary relative to IMD 110. The location of contact point P on outer perimeter PO may vary as driver body 104 slips over and/or grips outer perimeter PO.

[0059] In examples, a location of snare contact point PS relative to protracted portion 106 and/or snare 122 IMD 110 may vary as torque TI is imparted to driver body 104. For example, snare contact point PS may be a portion of (e.g., a point on) a surface defined by an outer perimeter PP of protracted portion 106. Snare 122 may be configured to contact outer perimeter PP to establish and/or substantially maintain contact with protracted portion 106. The location of snare contact point PS on outer perimeter PP may vary as snare 122 contacts outer perimeter PP to establish and/or substantially maintain contact with protracted portion 106. For example, as torque Tl imparts to driver body 104, snare 122 may substantially alternate between slipping over outer perimeter PP, such that snare 122 moves relative to protracted portion 106, and substantially gripping outer perimeter

PP, such that snare 122 is substantially stationary relative to protracted portion 106. The location of snare contact point PS on outer perimeter PP may vary as snare 122 slips over and/or grips outer perimeter PP.

[0060] Protracted portion 106 may be configured to substantially guide snare 122 from IMD perimeter PR to driver lumen opening 125 when snare loop 126 surrounds IMD perimeter PR and protracted portion 106 traps snare 122 between IMD perimeter PR and protracted portion 106. Protracted portion 106 may be configured to substantially keep snare 122 between IMD perimeter PR and protracted portion 106 when lumen opening boundary 156 and/or driver lumen inner surface 154 imparts a tensile force on snare 122 (e.g., when torque TI is imparted to driver body 104). For example, protracted portion 106 may be configured to substantially maintain snare 122 between protracted portion 106 and IMD perimeter PR as lumen opening boundary 156 and/or driver lumen inner surface 154 imparts the tensile force on snare 122 rather than, for example, allowing snare 122 to extend from IMD perimeter PR to driver lumen opening 125 without contacting protracted portion 106. For example, protracted portion 106 may be configured to limit and/or substantially prevent a tendency of snare 122 to substantially slip out of its position between IMD perimeter PR and protracted portion 106 when lumen opening boundary 156 and/or driver lumen inner surface 154 imparts the tensile force to snare 122. In examples, protracted portion 106 is configured to substantially trap snare 122 at a position proximal to (e.g., displaced in the proximal direction P from) a distal end 158 of protracted portion 106 (“protracted portion distal end 158”).

[0061] In examples, protracted portion 106 may be configured to substantially redirect a path of snare 122 from IMD perimeter PR to driver lumen opening 125 when driver body 104 pivots or attempts to pivot around contact point P relative to IMD 110. For example, protracted portion 106 may be configured to redirect snare 122 from a path PT1 (FIG. 5) defined by snare 122 to a path PT2 (FIG. 6) defined by snare 122. Snare 122 may define path PT1 as snare 122 extends from IMD perimeter PR to driver lumen opening 125 in the absence of torque T1 on driver body 104. Snare 122 may define path PT2 as snare 122 extends from IMD perimeter PR to driver lumen opening 125 when torque T1 is imparted to driver body 104. Protracted portion 106 may redirect snare 122 from the path PT1 to the path PT2 as protracted portion 106 traps snare 122 between IMD perimeter PR and protracted portion 106. In examples, when protracted portion 106 redirects and/or substantially maintains a path defined by snare 122 (e.g., path PT2), protracted portion exerts the force F3 on snare 122.

[0062] Driver 102 may be configured such that a torque on driver body 104 increases a tensile force on snare 122 caused initially by proximal force FS on snare 122 For example, snare 122 may be configured to translate through driver lumen 128 when snare loop 126 surrounds IMD perimeter PR and proximal force FS is exerted on snare 122 (e.g., snare distal portion 121). Driver body 104 may be configured such that when protracted portion 106 contacts IMD 110, driver body 104 (e.g. lumen opening boundary 156) acts to substantially redirect proximal force FS to generate an first tension in snare 122 in a direction oblique to (e.g., substantially perpendicular to) device axis LD of IMD 110. This first tension may generate some degree of frictional engagement between snare loop 126 and IMD perimeter PR. Driver 102 may be configured such that torque T1 imparted to driver body 104 causes lumen opening boundary 156 and/or driver lumen inner surface 154 to impart a second tensile force (e.g., force Fl) on snare 122 which is additive to the first tensile force. Hence, driver 102 may be configured to substantially increase the tensile force on snare 122 over that which might result solely from proximal force FS applied to snare distal portion 121. Driver 102 may be configured to substantially combine proximal force FS and torque T1 to generate the tensile force on snare 122 such that, for example, a magnitude of the proximal force FS necessary to generate a satisfactory frictional engagement between snare loop 126 and IMD perimeter PR may be reduced by imparting torque T1 on driver body 104.

[0063] In examples, protracted portion 106 is configured to substantially trap snare 122 between IMD perimeter PR and protracted portion 106 using a first leg or a second leg. The first leg and the second leg may, for example, reduce a degree of rotation around longitudinal axis L required for protracted portion 106 to contact IMD 110, reduce a likelihood that protracted portion 106 fails to trap snare 122 when contact with IMD 110 occurs, or for other reasons. In examples, the first leg and/or the second leg extend distal to driver lumen opening 125.

[0064] For example, FIG. 7 is a schematic illustration of driver 102 defining an example protracted portion 159 including a first leg 160 and a second leg 162. Protracted portion 159 is an example of protracted portion 106. First leg 160 and second leg 162 extend distal to driver lumen opening 125. Driver 102 may be configured such that first leg 160 contacts and/or substantially maintains contact with IMD 110 when a torque is imparted to driver body 104 in the first rotational direction Wl. Driver 102 may be configured such that second leg 162 contacts and/or substantially maintains contact with IMD 110 when a torque is imparted to driver body 104 in the second rotational direction W2. Either of first leg 160 or second leg 162 may contact IMD 110 at contact point P and/or contact snare 122 at snare contact point PS.

[0065] In examples, driver body 104 is configured such that lumen opening boundary 156 is defined substantially between first leg 160 and second leg 162. In examples, driver body 104 defines a stem portion 161 defining lumen opening boundary 156 and/or driver lumen opening 125. Driver body 104 may be configured such that first leg 160 and/or second leg 162 extend distally (e.g., in the distal direction D) from stem portion 161. In examples, first leg 160 includes a first end portion 164 (“first leg first portion 64”) attached to stem portion 161 and a second end portion 166 (“first leg second portion 166”) opposite first leg first portion 164. In examples, second leg 162 includes a first end portion 168 (“second leg first portion 168”) and a second end portion 170 (“second leg second portion 170”) opposite second leg first portion 168. In examples, first leg second portion 166 defines a distal end 172 of first leg 160 (“first distal end 172”). Second leg second portion 170 may define a distal end 174 of second leg 162 (“second distal end 174”). [0066] In examples, driver body 104 (e.g., stem portion 161) is configured to define lumen opening boundary 156 and/or driver lumen opening 125 substantially between first leg first portion 164 and second leg first portion 168. Driver body 104 may be configured such that lumen opening boundary 156 and/or driver lumen opening 125 separates first leg first portion 164 and second leg first portion 168. In examples, first leg 160 defines an axis LI (“first leg axis LI”) extending from first leg first portion 164 to first leg second portion 166 (e.g., first distal end 172). Second leg 162 may define an axis L2 (“second leg axis L2”) extending from second leg first portion 168 to second leg second portion 170 (e.g., second distal end 174). First leg axis LI and/or second leg axis L2 may define torque axis TA (FIG. 5, 6). In examples, first leg axis LI and/or second leg axis L2 are substantially parallel to longitudinal axis L.

[0067] FIG. 8 is a schematic illustration of driver 102 defining an example protracted portion 176. Protracted portion 176 is an example of protracted portion 106, 159. In examples, protracted portion 176 includes a bridging member 178 configured to extend from first leg 160 to second leg 162. Bridging member 178 may be configured to contact some portion of IMD 110 when protracted portion 176 contacts and/or substantially maintains contact with IMD 110 (e.g., at contact point P). In examples, bridging member 178 extends from first leg second portion 166 to second leg second portion 170 of protracted portion 176.

[0068] In examples, protracted portion 176 defines an access 180 configured to assist protracted portionl76 in trapping (e.g., maintaining a position of) snare 122 between IMD perimeter PR and protracted portion 176. Driver body 104 may define a boundary 182 of access 180 (“access boundary 182”) which defines access 180. Driver 102 may be configured such that, when snare 122 extends through driver lumen opening 125 and snare loop 126 surrounds IMD perimeter PR, snare 122 extends through access 180. Access boundary 182 may be configured to substantially keep snare 122 extending through access 180 when a torque (e.g., torque Tl) is imparted to driver body 104, such that snare 122 remains trapped between IMD perimeter PR and protracted portion 176. Access boundary 182 may be configured to assist in maintaining a position of snare 122 between protracted portion 176 and the IMD perimeter PR as the torque on driver body 104 causes driver body 104 to impart a tensile force on snare 122 rather than, for example, allowing the tensile force to cause snare 122 to a position outside of access 180. In examples, first leg 160, second leg 162, bridging member 178, and/or stem portion 161 define access boundary 182.

[0069] FIG. 9 is a schematic illustration of driver 102 defining an example protracted portion 184. Protracted portion 184 is an example of protracted portion 106, 159, 176. In examples, protracted portion 176 includes a wall section 186 extending between first leg 160, second leg 162, and/or bridging member 178. In examples, wall section 186, first leg 160, second leg 162, and/or bridging member 178 may define a cavity 188. In examples, access 180 opens to cavity 188. Driver lumen opening 125 may open into cavity 188, such that snare 122 may slidably translate within driver lumen 128 to extend through driver lumen opening 125, cavity 188, and access 180. Cavity 188 may be configured to assist in causing snare 122 to extend through access 180 when snare 122 translates distally through driver lumen opening 125 and/or when a torque (e.g., torque Tl) is imparted to driver body 104. For example, wall section 186 may define one or more surfaces configured to assist in causing snare 122 to extend through access 180 when snare 122 translates distally through driver lumen opening 125 and/or when a torque (e.g., torque Tl) is imparted to driver body 104. The one or more surfaces may comprise at least a portion of a boundary of cavity 188.

[0070] FIG. 10 illustrates medical system 100 with a cross-section view of driver 102 and delivery catheter 134, with the cross-section cutting plane taken through longitudinal axis L. Attachment member 118 is engaged with a tissue wall 141 such that IMD 110 remains anchored to tissues within or in proximity to target site 120.

[0071] Snare 122 is configured to translate within driver lumen 128 both distally (e.g., in the distal direction D) and/or proximally (e.g., in the proximal direction P) relative to driver 102 and delivery catheter 134. Snare 122 may extend through driver lumen opening 125 to translate within driver lumen 128. Driver 102 may be configured to translate within delivery catheter lumen 144 both distally and/or proximally relative to snare 122 and delivery catheter 134. Delivery catheter 134 may be configured to translate both distally and/or proximally relative to snare 122 and driver 102. Snare 122 may extend through driver lumen opening 125 to translate within driver lumen 128.

[0072] Snare 122 is configured to engage IMD 110 (e.g. IMD retrieval structure 111) when snare loop 126 is positioned around or in proximity to IMD retrieval structure 111. For example, snare loop 126 may define a loop aperture 190 configured to receive (e.g., substantially surround) at least some portion of IMD retrieval structure 111 when snare loop 126 is positioned around or in proximity to IMD retrieval structure 111. Snare 122 may be configured to cause snare loop 126 (e.g., loop aperture 190) to substantially constrict around IMD retrieval structure 111 when snare loop 126 is engaged with IMD retrieval structure 111. For example, snare 122 may be configured such that, when snare loop 126 engages IMD retrieval structure 111, proximal force FS exerted on snare body 124 causes snare loop 126 (e.g., loop aperture 190) to constrict around IMD retrieval structure 111.

[0073] In some examples, snare 122 includes a snare sheath defining a sheath lumen. The snare sheath may be configured to slidably translate within driver lumen 128. Snare body 124 and/or snare loop 126 may be configured to slidably translate within the sheath lumen, such that a clinician may cause movement of the snare sheath (e.g., distal and/or proximal movement) relative to snare body 124 and/or snare loop 126. For example, a clinician may cause the snare sheath to translate distally relative to driver body 104 when snare loop 126 is engaged with IMD retrieval structure 111 to cause snare loop 126 to constrict around IMD retrieval structure 111. Translation of the snare sheath toward snare loop 126 may cause some portion of snare loop 126 to enter the sheath lumen, at least partially collapsing loop aperture 190 and constricting snare loop 126 around retrieval structure 111. In examples, the snare sheath includes a snare sheath distal portion configured to be intracorporeal to the patient (e.g., via driver lumen 128) and a snare sheath proximal portion configured to be extracorporeal to the patient when the snare sheath distal portion is intracorporeal.

[0074] Snare body 124 and/or snare loop 126 may translate (e.g., within driver lumen 128 and/or a lumen defined by the snare sheath) in the distal direction D and/or the proximal direction P relative to driver 102, delivery catheter 134, and/or IMD 110. Snare body 124 may be configured such that a force exerted on snare body 124 (e.g., exerted on snare proximal portion 123, by a clinician) causes a translation of snare body 124 within driver lumen 128 and/or the sheath lumen, and the translation of snare body 124 causes a translation of snare loop 126. Snare body 124 may be configured to alter a position of snare 122 relative to driver 102, delivery catheter 134, and/or IMD 110. For example, snare 122 may be translated (e.g., by a clinician exerting a force on snare body 124) in the distal direction D substantially toward IMD 110 to place snare loop 126 in proximity to IMD retrieval structure 111. Some portion of snare 122 (e.g., snare body 124) may be translated (e.g., by a clinician exerting a force on snare body 124) in the proximal direction P substantially away from IMD 110 to cause snare loop 126 to constrict around IMD retrieval structure 111, and/or the snare sheath may be translated (e.g., by the clinician) distally relative to snare 122 to cause snare loop 126 to constrict around IMD retrieval structure 111. Snare 122 may be configured to translate within driver lumen 128 and/or the sheath lumen such that snare loop 126 positions either distal to or proximal to delivery receptacle opening 148.

[0075] Driver body 104 is configured to translate within delivery catheter lumen 144 to cause protracted portion 106, 176, 184 to contact IMD 110 (e.g., IMD retrieval structure 111). Driver body 104 may translate (e.g., within delivery catheter lumen 144) in the distal direction D and/or the proximal direction P relative to snare 122, delivery catheter 134, and/or IMD 110. Driver body 104 may be configured such that a force exerted on driver body 104 (e.g., exerted on driver body proximal portion 107, by a clinician) causes a translation of driver body 104 within delivery catheter lumen 144, and the translation of driver body 104 causes a translation of protracted portion 106, 176, 184. Driver body 104 may be configured to alter a position of protracted portion 106, 176, 184 relative to snare 122, delivery catheter 134, and/or IMD 110. For example, protracted portion 106, 176, 184 may be moved (e.g., by a clinician exerting a force on driver body 104) in the distal direction D substantially toward IMD 110 to cause protracted portion 106, 176, 184 to engage IMD retrieval structure 111. Protracted portion 106, 176, 184 may be moved (e.g., by a clinician exerting a force on driver body 104) in the proximal direction P substantially away from IMD 110 to cause protracted portion 106, 176, 184 to disengage from IMD retrieval structure 111. Driver body 104 may be configured to translate within delivery catheter lumen 144 such that protracted portion 106, 176, 184 and/or other portions of driver body 104 position distal to and/or proximal to delivery receptacle opening 148.

[0076] Snare 122 may be configured to surround and/or constrict around any portion of IMD 110 (e.g., around either IMD distal portion 116 or IMD proximal portion 114). In examples, when snare 122 constricts around a portion of IMD 110 distal to IMD retrieval structure 111, snare 122 may proximally translate (e.g., be proximally translated by a clinician) relative to IMD 110 such that snare loop 126 constricts around IMD retrieval structure 111. In examples, IMD retrieval structure 111 defines a stem 192 (“IMD stem 192”) and a crown 194 (“IMD crown 194”) proximal to IMD stem 192. IMD crown 194 may be configured to substantially cease a proximal translation of snare 122 when snare loop 126 constricts around IMD stem 192, such that snare 122 remains engaged with IMD 110. Protracted portion 106, 176, 184 may be configured to contact IMD crown 194, IMD stem 192, and/or another portion of IMD 110 when driver 102 contacts IMD 110. In examples, stem 192 defines a stem cross-sectional dimension substantially perpendicular to device axis LD and IMD crown 194 defines a crown cross-sectional dimension substantially perpendicular to device axis LD. The stem cross-sectional dimension may be less than the crown cross-sectional dimension. In some examples, IMD 110 (e.g., housing 206) defines an IMD cross-sectional dimension substantially perpendicular to device axis LD. The stem cross-sectional dimension may be less than the IMD cross-sectional dimension.

[0077] IMD 110, which in some examples can comprise a pacemaker such as a leadless and/or wholly intracardiac pacemaker, may include one or more electrodes such as electrode 202 supported by attachment member 118, electrode 204 supported by a housing 206 of IMD 110 (“IMD housing 206”), and/or electrode 208 (e.g., a return electrode) supported by IMD housing 206. One or more of electrodes 202, 204, 208 may be electrically connected to operating circuitry 210. Operating circuitry 210 may be configured to deliver therapy to a patient and/or sense physiological signals of the patient using electrodes 202, 204, 208. In examples, at least a portion of operating circuitry 210 is supported by IMD housing 206. In some examples, at least a portion of operating circuitry 210 is supported by another device displaced from IMD 110, such as another device within the patient and/or another device extracorporeal to the patient.

[0078] Driver body 104 may be configured to bend and/or define curvatures (e.g., within vasculature of a patient) as well as transfer torque to protracted portion 106, 176, 184. In examples, driver body 104 defines a flexible portion supporting and/or contiguous with protracted portion 106, 176, 184. The flexible portion may be, for example, a portion of driver body 104 proximal to protracted portion 106, 176, 184 (e.g., one or more portions of driver body distal portion 105 and/or driver body proximal portion 107). In examples, protracted portion 106, 176, 184 defines a first stiffness and the flexible portion defines a second stiffness, wherein the first stiffness is greater than the second stiffness. The first stiffness may be indicative of an extent to which protracted portion 106, 176, 184 resists deformation in response to a force (e.g., a compression force exerted by snare 122 or IMD 110) on protracted portion 106, 176, 184. The second stiffness may be indicative of an extent to which the flexible portion resists deformation in response to the force. Hence, the flexible portion (having the lower stiffness) may be configured to bend and/or define curvatures while protracted portion 106, 176, 184 (having the higher stiffness) transfers torque from protracted portion 106, 176, 184 to IMD 110.

[0079] Some portion of or substantially all of snare loop 126 may be configured to slidably translate within driver lumen 128 (e.g., in the absence of or via a sheath lumen) when snare body 124 translates within driver lumen 128 (e.g., in the absence of or via a sheath lumen). For example, snare loop 126 may be configured to at least partially collapse to slidably translate within driver lumen 128. In examples, snare body 124 is sufficiently flexible to define a curved and/or curvilinear shape within driver lumen 128. In some examples, snare body 124 may be sufficiently rigid to cause snare loop 126 to extend distally beyond driver lumen opening 125 to engage with (e.g., capture) IMD 110. Snare loop 126 and/or snare body 124 may be resiliently biased such that snare loop 126 substantially establishes a particular orientation relative to snare body 124 when snare loop 126 is unconstrained by driver lumen 128. For example, snare loop 126 and/or snare body 124 may be resiliently biased such that snare loop 126 and snare body 124 define an angle (e.g., an angle of about 90 degrees, about 45 degrees, or some other angle) when snare loop 126 is unconstrained by driver lumen 128.

[0080] In examples, IMD 110 (e.g., IMD retrieval structure 111) defines one or more device recesses configured to receive protracted portion 106, 176, 184 when protracted portion 106, 176, 184 contacts IMD 110. For example, FIG. 11 is a schematic illustration of an IMD 110 including device recess 196 and device recess 198, with device axis LD perpendicular to the page. In FIG. 11, the distal direction D proceeds into the page while the proximal direction P proceeds out of the page. IMD stem 192 is hidden by IMD crown 194 and illustrated in dashed lines.

[0081] Device recess 196, 198 may be configured such that protracted portion 106, 176, 184 substantially slots into device recess 196, 198 as torque T1 is imparted on driver body 104. Device recesses 196, 198 may be configured to resist translation (e.g., slipping and/or rolling) of protracted portion 106, 176, 184 around a perimeter defined by IMD 110 (e.g., outer perimeter PO) when torque T1 is imparted on driver body 104. In examples, device recess 196, 198 are configured such that protracted portion 106, 176, 184 establishes contact point P within device recess 196, 198. In some examples, protracted portion 106, 176, 184 is configured to transfer a torque from driver body 104 (e.g., a torque imparted by a clinician) to IMD 110 when the protracted portion 106, 176, 184 inserts into device recess 196, 198. For example, driver 102 may be configured such that, when torque T1 is applied to driver body 104, driver body 104 imparts a first portion of torque T1 to device recess 196 or device recess 198 and imparts a second portion of torque T1 to snare body 124. The first portion of torque T1 and the second portion of torque T1 may cause driver body 104 and snare body 124 to rotate substantially around device axis LD and/or cause IMD 110 to rotate substantially about device axis LD.

[0082] In examples, snare 122 is configured to cause protracted portion 106, 176, 184 to exert a contact force against IMD 110 (e.g., IMD retrieval structure 111) to substantially maintain protracted portion 106, 176, 184 inserted in device recess 196, 198. Snare 122 may be configured to cause protracted portion 106, 176, 184 to exert the contact force when proximal force FS is imparted (e.g., by a clinician) on snare 122. In examples, medical system 100 may be configured such that torque T1 on driver body 104 causes protracted portion 106, 176, 184 to substantially roll and/or slip around a perimeter defined by IMD 110 (e.g., outer perimeter PO) to cause the protracted portion 106, 176, 184 to insert within device recess 196 or device recess 198. In examples, device recess 196 and/or device recess 198 is configured to substantially capture (e.g., to catch) protracted portion 106, 176, 184 as protracted portion 106, 176, 184 substantially rolls and/or slips around the perimeter defined by IMD 110.

[0083] As used herein, when protracted portion 106, 176, 184 substantially slips and/or rolls around a perimeter defined by IMD 110 (e.g., outer perimeter PO), this may mean that protracted portion 106, 176, 184 rotates about longitudinal axis L and relative to IMD 110 (e.g., IMD retrieval structure 111) as protracted portion 106, 176, 184 contacts the perimeter defined by IMD 110. In examples, driver body 104 and protracted portion 106, 176, 184 angularly displace relative to IMD 110 when protracted portion 106, 176, 184 substantially rolls or slips around the perimeter defined by IMD 110.

[0084] As discussed, medical system 100 is configured such that snare 122 (e.g., snare loop 126) frictionally engages IMD 110 (e.g., IMD retrieval structure 111) when snare loop 126 constricts around IMD 110 and driver body 104 causes snare 122 to rotate around device axis LD. Driver 102 is configured such that torque T1 imparts a tensile force to snare 122 to increase the frictional engagement. The frictional engagement of snare loop 126 and IMD 110 as snare 122 rotates around device axis LD may impart a torque on IMD 110, causing IMD 110 to revolve about device axis LD.

[0085] In examples, snare 122 defines a textured surface (e.g., a surface defining a texture such as a surface roughness and/or surface undulations) configured to assist and/or increase the frictional engagement with IMD 110. The textured surface may define, for example, a surface roughness or an undulating surface. The surface roughness may be characterized by, for examples, a profile roughness parameter (e.g., Ra, Rz, Rq, or another roughness parameter) indicative of a deviation from an ideal surface. The snare surface may be configured such that when snare loop 126 tightens around IMD 110, the surface roughness enhances and/or increases the frictional force between snare 122 (e.g., the snare surface) and IMD 110 when snare 122 causes the snare surface to impart a rotational torque (e.g., rotation torque TR (FIG. 6)) on IMD 110. The surface undulations may be characterized by an surface of snare loop 126 configured to exhibit a sinuous shape, wavelike shape, or other shape wherein a mean surface level defines a varying radial displacement from an snare axis extending within a body of the snare loop. For examples, the surface undulations may be defined by a coil defining snare loop 126, a plurality of ridges and/or depressions defined on the snare surface, or other surface features configured to define the textured surface.

[0086] In examples, IMD 110 (e.g., IMD retrieval structure 111 and/or housing 206) defines one or more structure protrusions located around IMD perimeter PR configured to assist the transfer of torque from snare 122 to IMD 110. In examples, the one or more structure protrusions may be configured to assist and/or increase a frictional engagement of snare 122 with IMD 110. In examples, the one or more structure protrusions define some portion of IMD perimeter PR. For example, as depicted in FIG. 11, IMD 110 (e.g., IMD stem 192) may define a protrusion 212 (e.g., a corner) configured to assist the transfer of torque from snare 122 to IMD 110.

[0087] In examples, at least a portion of IMD perimeter PR defines a polygonal curve, and protrusion 212 defines at least a portion of the polygonal curve. IMD perimeter PR may define a polygon such as, for example, a hexagon, octagon, or other polygon. In some examples, at least a portion of IMD perimeter PR defines a curved or curvilinear segment, and protrusion 212 defines at least a portion of the curved or curvilinear segment. Protrusion 212 may be configured to substantially bear against some portion of snare 122 (e.g., a portion comprising the snare surface, such as an undulation of the snare surface) when snare 122 frictionally engages IMD 110. Protrusion 212 may be configured such that snare 122, when snare 122 generates the rotation torque TR in IMD 110, snare 122 bears against protrusion 212 to transmit a contact force on protrusion 212. In examples, protrusion 212 defines a bearing surface configured to contact snare 122 (e.g., the snare surface) when snare 122 transfers the contact force. In examples, the bearing surface is configured such that the contact force includes one or more force components having a direction substantially normal and/or oblique to the bearing surface. In examples, when snare 122 exerts the contact force on protrusion 212, the bearing surface acts to minimize and/or limit relative movement between snare 122 and protrusion 212, such that snare 122 substantially grips IMD perimeter PR.

[0088] In examples, IMD 110 (e.g., IMD retrieval structure 111 and/or housing 206) defines a plurality of structure protrusions arranged substantially circumferentially around device axis LD. For example, in addition to protrusion 212, IMD stem may define protrusion 214, protrusion 216, protrusion 218, protrusion 220, and/or protrusion 222. Each of protrusions 214, 216, 218, 220, 222 may be configured similarly to structure protrusion 212. For example, each of protrusions 214, 216, 218, 220, 222 may define an individual portion of IMD perimeter PR. Each of protrusions 214, 216, 218, 220, 222 may define an individual polygonal curve defined by IMD perimeter PR. Each of protrusions 214, 216, 218, 220, 222 may define a curved or curvilinear segment defined by IMD perimeter PR. Each of protrusions 214, 216, 218, 220, 222 may include an individual bearing surface configured to receive an individual contact force from snare 122, such that one or more of protrusions 214, 216, 218, 220, 222 may acts to minimize and/or limit relative movement between snare 122 and IMD 110. In examples, protrusions 212, 214, 216, 218, 220, 222 are arranged such that each of protrusions 212, 214, 216, 218, 220, 222 extend in direction radially outward from device axis LD.

[0089] Referring to, for example, FIG. 10, operating circuitry 210 may include fixed function circuitry and/or programmable operating circuitry. In examples, operating circuitry 210 may include circuitry configured to perform one or more functions of operating circuitry 210, such as therapy delivery circuitry, sensing circuitry, processing circuitry, switching circuitry, communication circuitry, and/or other circuitries. Operating circuitry 210, as well as other processors, processing circuitry, controllers, control circuitry, and the like, described herein, may include any combination of integrated circuitry, discrete logic circuity, analog circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), or field- programmable gate arrays (FPGAs). In some examples, operating circuitry 210 includes multiple components, such as any combination of one or more microprocessors, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry, and/or analog circuitry.

[0090] Functions attributed to operating circuitry 210 may be embodied as software, firmware, hardware or any combination thereof. Operating circuitry 210 may include, for instance, a variety of capacitors, transformers, switches, and the like configured to perform the functions of operating circuitry 210. In examples, operating circuitry 210 may be configured to communicate with another device, such as a patient input/output device, a clinician input/output device, and/or others. Operating circuitry 210 may include any suitable hardware, firmware, software or any combination thereof for communicating with another device. In addition, operating circuitry 210 may communicate with a networked computing device and a computer network. In examples, operating circuitry 210 and/or other circuitry of medical system 100 is configured to deliver stimulation signals to and/or receive sensing signals from electrodes 202, 204, 208 and/or other electrodes and/or sensors within medical system 100 or external to medical system 100. Operating circuitry 210 may be configured to provide electrical signals, e.g., pacing therapy, to electrodes 202, 204, 208. Operating circuitry 210 may be configured to receive electrical signals, e.g., sensed cardiac electrical signals, from electrodes 202, 204, 208.

[0091] Medical system 100 (e.g., operating circuitry 210) can also include memory configured to store program instructions, such as software, which may include one or more program modules, which are executable by operating circuitry 210. The program instructions may be embodied in software and/or firmware. The memory can include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically - erasable programmable ROM (EEPROM), ferroelectric RAM (FRAM), flash memory, or any other digital media. In some examples, the memory includes computer-readable instructions that, when executed by operating circuitry 210 cause operating circuitry 210 to perform various functions described herein and/or other functions of operating circuitry 210.

[0092] IMD housing 206 may enclose operating circuitry 210 and/or other circuitry within medical system 100. IMD housing 206 may be configured to fluidly isolate operating circuitry 210 and/or other circuitry from an environment in contact with an exterior surface of IMD housing 206. In examples, IMD housing 206 is configured to hermetically seal an enclosure defined by IMD 110 and holding operating circuitry 210 and/or other circuitry. IMD housing 206 may be configured to define shapes that are easily accepted by the patient's body while minimizing patient discomfort. For example, IMD housing 206 may define a substantially cylindrical shape with cylindrical sidewalls. In other examples, IMD housing 206 may define substantially rectangular or other non- cylindrical shapes. IMD housing 206 may define shapes in which corners and edges are designed with relatively large radii, in order to present a housing having smoothly contoured exterior surfaces. In examples, attachment member 118 is coupled to IMD housing 206.

[0093] A technique for imparting a torque using a medical system 100 is illustrated in FIG. 12. Although the technique is described mainly with reference to medical system 100 of FIGS. 1- 11, the technique may be applied to other medical systems in other examples.

[0094] The technique includes surrounding an IMD perimeter PR defined by an IMD 110 with a snare 122 (1202). In some examples, a snare 122 surrounds IMD perimeter PR using a snare loop 126. Snare loop 126 may exert a proximal force on IMD 110 when a proximal force FS is exerted (e.g., by a clinician) on a snare body 124 supporting snare loop 126. Snare body 124 and/or snare loop 126 extends through a driver lumen 128 and a driver lumen opening 125 defined by a driver body 104 of a driver 102 when snare 122 surround IMD perimeter PR. Snare loop 126 may at least partially collapse and/or constrict (e.g., around IMD perimeter PR) when snare body 124 slidably translates within driver lumen 128. In examples, a snare sheath is translated (e.g., translated distally) relative to snare body 124 to constrict snare loop 126 around IMD perimeter PR.

[0095] The technique includes trapping snare loop 126 between IMD perimeter PR and a protracted portion 106, 176, 184 defined by driver body 104 and extending distal to driver lumen opening 125 (1204). In examples, protracted portion 106, 176, 184 contacts IMD 110 to trap snare loop 126 when snare loop 126 surrounds IMD perimeter PR. In examples, one of a first leg 160 or a second leg 162 of protracted portion 106, 176, 184 traps snare loop 126 when snare loop 126 surrounds IMD perimeter PR. In examples, snare 122 extends through driver lumen opening 125 and through an access 180 defined by first leg 160, second leg 162, a bridging member 178, and/or a wall section 186 when snare loop 126 surrounds IMD perimeter PR.

[0096] The technique includes imparting a torque Tl, using a driver body 104 of driver 102, on protracted portion 106, 176, 184 (1206). Driver body 104 may impart torque Tl on protracted portion 106, 176, 184 to cause protracted portion 106, 176, 184 to rotate and/or attempt to rotate relative to IMD 110. In examples, driver body 104 pivots and/or attempts to pivot around a contact point P when torque Tl imparts to driver body 104.

[0097] Imparting torque Tl to driver 102 may cause a lumen opening boundary 156 and a driver lumen inner surface 154 to experience a torque around a torque axis TA defined by protracted portion 106, 176, 184 when driver body 104 pivots or attempts to pivot around contact point P. In examples, a radial displacement RD between torque axis TA and lumen opening boundary 156 and/or lumen inner surface 154 causes the resulting torque around torque axis TA on lumen opening boundary 156 and a driver lumen inner surface 154. The resulting torque on lumen opening boundary 156 and driver lumen inner surface 154 may cause lumen opening boundary 156 and/or driver lumen inner surface 154 to exert a force (e.g., a force Fl) on snare 122 as snare 122 extends through driver lumen opening 125. In examples, lumen opening boundary 156 and/or driver lumen inner surface 154 exert the force Fl in a direction substantially away from IMD 110 when torque Tl is imparted to driver body 104. The force Fl may cause IMD 110 (e.g., IMD perimeter PR) to exert an opposing force F2 on snare loop 126, increasing a tensile force in snare 122. The tensile force may increase the frictional engagement of snare loop 122 with IMD perimeter PR.

[0098] Protracted portion 106, 176, 184 may contact snare 122 (e.g., at snare contact point PS) as snare 122 extends from IMD perimeter PR to lumen opening boundary 156. Protracted portion 106, 176, 184 may trap snare 122 to substantially maintain contact with snare 122 (e.g., at snare contact point PS), such that when driver body 104 pivots or attempts to pivot around torque axis TA, protracted portion 106, 176, 184 constrains snare 122 to extend around some portion of protracted portion 106, 176, 184. In examples, protracted portion 106, 176, 184 exerts a force (e.g., a force F3) on snare 122 as torque T1 imparts to driver body 104 and protracted portion 106, 176, 184 traps snare 122 between IMD perimeter PR and protracted portion 106, 176, 184. The force F3 may act to increases the tensile force in snare 122.

[0099] The increased tensile force on snare 122 caused by torque T1 may increase the contact force imparted by protracted portion 106, 176, 184 on IMD 110 (e.g., via contact point P) and/or may increase the frictional engagement of snare loop 126 with IMD perimeter PR. The increased contact force between protracted portion 106, 176, 184 and/or the increased frictional engagement between snare loop 126 and IMD perimeter PR may cause protracted portion 106, 176, 184 and IMD 110 to remain substantially stationary with respect to each other as the torque T1 imparts to driver body 104. When protracted portion 106, 176, 184 and IMD 110 maintain substantially stationary relative positions and torque T1 continues to cause the rotation of protracted portion 106, 176, 184 about longitudinal axis L, longitudinal axis L may substantially orbit around device axis LD of IMD 110. The orbiting of longitudinal axis L around device axis LD may cause driver body 104 to impart at least some portion of torque T1 to IMD 110 via snare loop 126, causing rotation of IMD 110 about device axis LD. The orbiting of longitudinal axis L around device axis LD may cause IMD 110 to rotate about device axis LD in a first rotational direction W1 or a second rotational direction W2. The rotation of IMD 110 about device axis LD may cause an attachment member 118 of IMD 110 to engage tissues at a target site 120, disengage tissues at target site 120, and/or otherwise cause a reorientation of IMD 110 within a patient.

[0100] The technique may include positioning, using a delivery catheter 134, at least a portion of snare 122, protracted portion 106, 176, 184, and/or driver body 104 within an anatomical volume of the patient. In examples, delivery catheter 134 positions at least a portion of snare 122, protracted portion 106, 176, 184, and/or driver body 104 within a chamber of a heart 101 of the patient. Delivery catheter 134 may transport at least a portion of snare 122, protracted portion 106, 176, 184, and/or driver body 104 through vasculature of the patient. In examples, at least a portion of snare 122, protracted portion 106, 176, 184, and/or driver body 104 positions within a delivery receptacle volume 142 defined by delivery catheter 134. Driver body 104 may cause protracted portion 106, 176, 184 to position within delivery receptacle volume 142 by translating through a delivery catheter lumen 144. Snare 122 may position within delivery receptacle volume by translating through a delivery catheter lumen 144.

[0101] Various examples of the disclosure have been described. Any combination of the described systems, operations, or functions is contemplated. These and other examples are within the scope of the following claims.

[0102] Example 1. A medical system, comprising: a driver configured to impart a torque on an implantable medical device within an anatomical volume defined by a body of a patient, wherein a driver body of the driver defines a lumen extending to a lumen opening in a distal portion of the driver body and defines a longitudinal axis extending through the lumen, and wherein the driver body defines a protracted portion extending distal to the lumen opening; and a snare configured to slidably translate within the lumen and extend through the lumen opening, the snare defining a snare loop configured to surround a perimeter of the implantable medical device, wherein the protracted portion is configured to contact the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare extends through the lumen opening and the snare loop surrounds the perimeter of the implantable medical device, and wherein the driver is configured to impart a tensile force to the snare when the snare loop surrounds the perimeter of the implantable medical device, the protracted portion traps the snare loop, and a torque around the longitudinal axis is imparted to the driver body.

[0103] Example 2. The medical system of Example 1, wherein the protracted portion is configured to exert a first force on the implantable medical device when the protracted portion traps the snare loop and the torque imparts to the driver body, wherein the driver is configured to exert a second force on the snare when the protracted portion exerts the first force, and wherein at least the second force imparts the tensile force to the snare.

[0104] Example 3. The medical system of Example 2, wherein the driver is configured such that the first force acts in a first direction and the second force acts in a second direction opposite the first direction.

[0105] Example 4. The medical system of any of Examples 1-3, wherein the protracted portion is configured to contact the implantable medical device at least at a contact point when the protracted portion traps the snare loop, and wherein the driver body is configured to pivot around the contact point when the snare loop surrounds the perimeter and the driver imparts the tensile force to the snare.

[0106] Example 5. The medical system of any of Examples 1-4, wherein the driver body is configured to impart a snare torque to the snare when the torque around the longitudinal axis is imparted to the driver body and the driver imparts the tensile force to the snare, wherein the snare torque is a torque around a device axis of the implantable medical device, and wherein the snare is configured to transfer the snare torque to the implantable medical device when the snare loop surrounds the perimeter.

[0107] Example 6. The medical system of any of Examples 1-5, wherein the driver is configured such that the longitudinal axis is radially displaced from a device axis of the implantable medical device when the driver imparts the tensile force to the snare.

[0108] Example 7. The medical system of Examples 1-6, wherein the protracted portion is configured to rotate about the longitudinal axis when the driver body rotates about the longitudinal axis.

[0109] Example 8. The medical system of any of Examples 1-7, wherein the driver body defines an inner surface of the lumen, and wherein the inner surface is configured to impart a force to the snare to cause the driver to impart the tensile force to the snare when the snare loop surrounds the implantable medical device, the protracted portions traps the snare loop, and the torque around the longitudinal axis is imparted to the driver body.

[0110] Example 9. The medical system of any of Examples 1-8, wherein the protracted portion is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a first rotational direction around the longitudinal axis and configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a second rotational direction opposite the first rotational direction.

[0111] Example 10. The medical system of any of Examples 1-9, wherein the snare is configured to transmit a force exerted on the snare in a proximal direction of the driver to the implantable medical device when the snare surrounds the perimeter.

[0112] Example 11. The medical system of any of Examples 1-10, wherein the protracted portion includes a first leg and a second leg, wherein the first leg and the second leg extend distal to the lumen opening, and wherein at least one of the first leg or the second leg is configured to contact the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare extends through the lumen opening and the snare loop surrounds the perimeter of the implantable medical device.

[0113] Example 12. The medical system of Example 11, wherein the driver body includes an opening boundary defining the lumen opening, and wherein the opening boundary is between the first leg and the second leg.

[0114] Example 13. The medical system of Example 11 or Example 12, wherein the first leg defines a first axis substantially parallel to the longitudinal axis and the second leg defines a second axis substantially parallel to the longitudinal axis.

[0115] Example 14. The medical system of any of Examples 11-13, wherein the driver body includes a bridging member extending from a distal portion of the first leg to a distal portion of the second leg.

[0116] Example 15. The medical system of any of Examples 11-14, wherein the first leg is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a first rotational direction around the longitudinal axis, and wherein the second leg is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a second rotational direction opposite the first rotational direction.

[0117] Example 16. The medical system of any of Examples 11-13, wherein the driver body defines a wall section extending between the first leg and the second leg, wherein the wall section, the first leg, and the second leg define a cavity within the driver body and a cavity opening which opens to the cavity, wherein the lumen opening opens to the cavity, and wherein the snare is configured to slidably translate within the lumen and extend through the lumen opening and the cavity opening.

[0118] Example 17. The medical system of Example 16, wherein the wall section is configured to guide the snare toward the cavity when the snare slidably translates within the lumen and extends through the lumen opening.

[0119] Example 18. The medical system of any of Examples 1-17, wherein the snare is resiliently biased to cause the snare loop to define an oblique angle with the longitudinal axis when the snare loop extends through the lumen opening.

[0120] Example 19. The medical system of any of Examples 1-18, further comprising the implantable medical device, wherein the implantable medical device defines a device axis extending from a distal portion of the implantable medical device to a proximal portion of the implantable medical device, wherein the proximal portion includes a retrieval structure, wherein the retrieval structure defines the perimeter of the implantable medical device, and wherein the protracted portion is configured to trap the snare loop between the protracted portion and the retrieval structure.

[0121] Example 20. The medical system of Example 19, wherein a housing of the implantable medical device defines an IMD cross-sectional dimension substantially perpendicular to the device axis, wherein the retrieval structure defines a stem defining a stem cross-sectional dimension substantially perpendicular to the device axis, wherein the stem cross-sectional dimension is less than the IMD cross-sectional dimension, and wherein the stem defines the perimeter of the implantable medical device.

[0122] Example 21. The medical system of Example 19 or Example 20, wherein the retrieval structure defines one or more recesses configured to receive the protracted portion when the protracted portion traps the snare loop.

[0123] Example 22. The medical system of any of Examples 19-21, wherein the protracted portion is configured to contact at least one of the housing of claim 20 or the retrieval structure when the protracted portion contacts the implantable medical device to trap the snare loop.

[0124] Example 23. The medical system of any of Examples 19-22, wherein the perimeter of the implantable medical device includes one or more line segments, wherein the one or more line segments include at least one of a straight line segment, a curved line segment, or a curvilinear line segment.

[0125] Example 24. The medical system of Example 23, wherein the defines the perimeter of the implantable medical device defines a polygonal curve.

[0126] Example 25. The medical system of any of Examples 18-24, wherein the implantable medical device includes an attachment member configured to at least one of engage tissue of the patient or disengage from tissue of the patient when the driver imparts the tensile force to the snare and the snare imparts a torque around the device axis to the implantable medical device.

[0127] Example 26. The medical system of any of Examples 1-25, further comprising a delivery catheter having a delivery receptacle, wherein the delivery receptacle defines a receptacle volume configured to receive at least a portion of the implantable medical device,

[0128] wherein the delivery catheter defines a delivery lumen and a delivery lumen opening, wherein the delivery lumen opening opens into the receptacle volume, and wherein the driver body is configured to slidably translate within the delivery lumen and pass through the delivery lumen opening.

[0129] Example 27. The medical system of Example 26, wherein the receptacle volume is configured to receive the protracted portion and the portion of the implantable medical device when the protracted portion traps the snare loop between the protracted portion and the implantable medical device.

[0130] Example 28. The medical system of Example 26 or Example 27, wherein the driver body is configured to rotate relative to the delivery receptacle when the protracted portion traps the snare loop between the protracted portion and the implantable medical device.

[0131] Example 29. The medical system of any of Examples 26-28, wherein the delivery catheter is configured transport at least a portion of the driver body and a portion of the snare through vasculature of the patient.

[0132] Example 30. A method, comprising: surrounding, using a snare loop of a snare extending through a lumen opening of a driver body of a driver, a perimeter defined by an implantable medical device; contacting, using a protracted portion of the driver body, the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare loop surrounds the perimeter; imparting, using the driver, a torque on the driver body; and imparting, using the driver, a tensile force to the snare when the snare loop surrounds the perimeter of the implantable medical device, the protracted portion traps the snare loop, and the driver imparts the torque to the driver body.

[0133] Example 31. The method of Example 30, further comprising imparting, using the snare loop, a torque around a device axis of the implantable medical device when the driver imparts the tensile force to the snare.

[0134] Example 32. The method of Example 31, wherein the torque imparted to the driver body is a torque around a longitudinal axis defined by the driver body, and wherein the perimeter of the implantable medical device is between the longitudinal axis and the device axis.

[0135] Example 33. The method of Example 31 or Example 32, wherein the perimeter is defined by a proximal portion of the implantable medical device, and further comprising transferring the torque to an attachment member attached to a distal portion of the implantable medical device.

[0136] Example 34. The method of any of Examples 30-33, further comprising: exerting, using the protracted portion, a first force on the implantable medical device when the protracted portion traps the snare loop and the torque imparts to the driver body; and exerting, using the driver, a second force on the snare when the protracted portion exerts the first force, wherein the second force imparts the tensile force to the snare.

[0137] Example 35. The method of any of Examples 30-34, further comprising: [0138] contacting the protracted portion and the implantable medical device at least at a contact point when the protracted portion traps the snare loop; and pivoting the driver body around the contact point when the driver imparts the tensile force to the snare.

[0139] Example 36. The method of any of Examples 30-35, further comprising imparting a force to the snare using an inner surface of the lumen to cause the driver to impart the tensile force to the snare when the snare loop surrounds the implantable medical device, the protracted portions traps the snare loop, and the torque around the longitudinal axis is imparted to the driver body, wherein the driver body defines the inner surface.

[0140] Example 37. The method of any of Examples 30-36, further comprising transferring, using the snare, a force in a proximal direction of the driver to the implantable medical device when the snare surrounds the perimeter.

[0141] Example 38. The method of any of Examples 30-37, wherein contacting the protracted portion and the implantable medical device to trap the snare loop further comprises at least one of contacting a first leg of the protracted portion and the implantable medical device or contacting a second leg of the protracted portion and the implantable medical device.

[0142] Example 39. The method of Example 38, further comprising contacting a bridging member and the implantable medical device when the protracted portion contacts the implantable medical device, wherein the bridging member extends from a distal portion of the first leg to a distal portion of the second leg. [0143] Example 40. The method of any of Examples 30-39, wherein imparting the tensile force to the snare includes at least one of: imparting the tensile force to the snare when the torque is imparted to the driver body in a first rotational direction, or imparting the tensile force to the snare when the torque is imparted to the driver body in a second rotational direction opposite the first rotational direction.

[0144] Example 41. The method of any Examples 30-40, further comprising delivering the driver to an anatomical volume defined by a body of a patient using a delivery catheter defining a receptacle volume, wherein the delivery catheter defines a delivery lumen and a delivery lumen opening that opens to the receptacle volume, and wherein the driver body is configured to slidably translate within the delivery lumen and pass through the delivery lumen opening.

Claims

WHAT IS CLAIMED IS:

1. A medical system, comprising: a driver configured to impart a torque on an implantable medical device within an anatomical volume defined by a body of a patient, wherein a driver body of the driver defines a lumen extending to a lumen opening in a distal portion of the driver body and defines a longitudinal axis extending through the lumen, and wherein the driver body defines a protracted portion extending distal to the lumen opening; and a snare configured to slidably translate within the lumen and extend through the lumen opening, the snare defining a snare loop configured to surround a perimeter of the implantable medical device, wherein the protracted portion is configured to contact the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare extends through the lumen opening and the snare loop surrounds the perimeter of the implantable medical device, and wherein the driver is configured to impart a tensile force to the snare when the snare loop surrounds the perimeter of the implantable medical device, the protracted portion traps the snare loop, and a torque around the longitudinal axis is imparted to the driver body.

2. The medical system of claim 1, wherein the protracted portion is configured to exert a first force on the implantable medical device when the protracted portion traps the snare loop and the torque imparts to the driver body, wherein the driver is configured to exert a second force on the snare when the protracted portion exerts the first force, and wherein at least the second force imparts the tensile force to the snare.

3. The medical system of claim 2, wherein the driver is configured such that the first force acts in a first direction and the second force acts in a second direction opposite the first direction.

4. The medical system of any of claims 1-3, wherein the protracted portion is configured to contact the implantable medical device at least at a contact point when the protracted portion traps the snare loop, and wherein the driver body is configured to pivot around the contact point when the snare loop surrounds the perimeter and the driver imparts the tensile force to the snare.

5. The medical system of any of claims 1-4, wherein the driver body is configured to impart a snare torque to the snare when the torque around the longitudinal axis is imparted to the driver body and the driver imparts the tensile force to the snare, wherein the snare torque is a torque around a device axis of the implantable medical device, and wherein the snare is configured to transfer the snare torque to the implantable medical device when the snare loop surrounds the perimeter.

6. The medical system of any of claims 1-5, wherein the driver is configured such that the longitudinal axis is radially displaced from a device axis of the implantable medical device when the driver imparts the tensile force to the snare.

7. The medical system of claims 1-6, wherein the protracted portion is configured to rotate about the longitudinal axis when the driver body rotates about the longitudinal axis.

8. The medical system of any of claims 1-7, wherein the driver body defines an inner surface of the lumen, and wherein the inner surface is configured to impart a force to the snare to cause the driver to impart the tensile force to the snare when the snare loop surrounds the implantable medical device, the protracted portions traps the snare loop, and the torque around the longitudinal axis is imparted to the driver body.

9. The medical system of any of claims 1-8, wherein the protracted portion is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a first rotational direction around the longitudinal axis and configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a second rotational direction opposite the first rotational direction.

10. The medical system of any of claims 1-9, wherein the snare is configured to transmit a force exerted on the snare in a proximal direction of the driver to the implantable medical device when the snare surrounds the perimeter.

11. The medical system of any of claims 1-10, wherein the protracted portion includes a first leg and a second leg, wherein the first leg and the second leg extend distal to the lumen opening, and wherein at least one of the first leg or the second leg is configured to contact the implantable medical device to trap the snare loop between the protracted portion and the implantable medical device when the snare extends through the lumen opening and the snare loop surrounds the perimeter of the implantable medical device.

12. The medical system of claim 11, wherein the first leg is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a first rotational direction around the longitudinal axis, and wherein the second leg is configured to cause the driver to impart the tensile force to the snare when the torque is imparted to the driver body in a second rotational direction opposite the first rotational direction.

13. The medical system of any of claims 1-12, further comprising the implantable medical device, wherein the implantable medical device defines a device axis extending from a distal portion of the implantable medical device to a proximal portion of the implantable medical device, wherein the proximal portion includes a retrieval structure, wherein the retrieval structure defines the perimeter of the implantable medical device, and wherein the protracted portion is configured to trap the snare loop between the protracted portion and the retrieval structure.

14. The medical system of claim 13, wherein a housing of the implantable medical device defines an IMD cross- sectional dimension substantially perpendicular to the device axis, wherein the retrieval structure defines a stem defining a stem cross-sectional dimension substantially perpendicular to the device axis, wherein the stem cross-sectional dimension is less than the IMD cross-sectional dimension, and wherein the stem defines the perimeter of the implantable medical device.

15. The medical system of claim 13 or claim 14, wherein the retrieval structure defines one or more recesses configured to receive the protracted portion when the protracted portion traps the snare loop.