Fixation components for implantable medical devices

Abstract

An example fixation component for an implantable medical device (IMD) includes: a base and a plurality of teeth configured to deploy with a target deployment stiffness to engage tissue at a target implantation site, while maintaining a target deflection stiffness after deployment. The base defines a longitudinal axis of the fixation component and is fixedly attached near a distal end of the IMD. Each tooth is spaced apart from each other around the periphery of the distal end of the IMD and extends from the base. The shape of each tooth is selected to control each of the target deployment stiffness and the target deflection stiffness.

Description

Technical Field

[0001] This disclosure relates to, for example, a relatively compact implantable medical device and associated fixation components of a medical device system. Background Technology

[0002] In some instances, implantable pacemakers include a pulse generator device to which one or more flexible, elongated leads are coupled. The pulse generator device can be implanted in a subcutaneous pouch remote from the heart, and each of the one or more leads extends from the device to a corresponding electrode coupled to the lead and located at the pacing site in the endocardium or epicardium. The elongated leads may present mechanical and / or MRI compatibility issues. Relatively compact implantable medical devices (IMDs) have been developed, entirely contained within a relatively compact package, configured for implantation, for example, within a chamber of the heart, adjacent to the pacing site. Summary of the Invention

[0003] This disclosure describes an IMD fixation component with improved flexibility, fixation, or both, to facilitate the implantation of an IMD comprising a relatively compact IMD. The IMD fixation component may include multiple teeth. Each corresponding tooth of the multiple teeth has a deployment stiffness that allows the corresponding tooth to penetrate tissue at the target implantation site. By controlling the deployment stiffness, the multiple teeth can have improved tissue fixation, including, for example, control over the tooth penetration depth and tissue engagement in the lateral direction. Each corresponding tooth of the multiple teeth also has a deflection stiffness that allows a clinician to confirm adequate fixation of the tooth in the patient's tissue. For example, a traction test or drag test can be performed under fluoroscopy to confirm that the multiple teeth have engaged with the tissue. By controlling the deflection stiffness, the multiple teeth can have improved flexibility, which allows a clinician to more easily confirm tissue engagement.

[0004] In some instances, a fixation component for an implantable medical device (IMD) may include a base defining a longitudinal axis of the fixation component and a plurality of teeth extending from the base and spaced apart from each other. The base may be fixedly attached to the IMD, which has proximal and distal ends aligned along the longitudinal axis. Each of the plurality of teeth may include a proximal portion and a distal portion. The proximal portion may include: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment outward from the longitudinal axis; a first straight segment extending laterally from the first curved segment outward from the longitudinal axis in a second direction; and a second curved segment defining a second deformable preformed curvature and extending laterally from the first straight segment outward from the longitudinal axis. The distal portion may include: a second straight section extending upward from the second curved section in a third direction oriented generally opposite to the first direction; a third curved section defining a third deformable preform curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0005] In some instances, a fixation component for an implantable medical device (IMD) may include a base defining a longitudinal axis of the fixation component and a plurality of teeth extending from the base and spaced apart from each other. The base may be fixedly attached to the IMD, which has proximal and distal ends aligned along the longitudinal axis. Each of the plurality of teeth may include a proximal portion and a distal portion. The proximal portion may include: a proximal segment fixedly attached to the base and extending in a first direction generally parallel to the longitudinal axis; and a first bending segment extending laterally from the proximal segment outward from the longitudinal axis, wherein the bending segment is configured to provide a deflection stiffness of less than about 0.6 Newtons. The distal portion may include: a second proximal segment extending from the first curved segment in a second direction oriented generally opposite to the first direction; a second curved segment having a deformable preformed curve and extending from the second proximal segment; and a tip segment extending from the second curved segment toward the longitudinal axis and terminating at a free distal end.

[0006] In some instances, an implantable medical device (IMD) may include: a housing extending from a proximal end to a distal end along a longitudinal axis; an electrode mounted near the distal end of the housing; and a fixation component. The fixation component may include a base near the distal end of the housing and a plurality of teeth fixedly attached to each other at intervals around the periphery of the distal end of the housing; each of the plurality of teeth may include a proximal portion and a distal portion. The proximal portion may include: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment outward from the longitudinal axis; a first straight segment extending laterally from the first curved segment outward from the longitudinal axis in a second direction; and a second curved segment defining a second deformable preformed curvature and extending laterally from the first straight segment outward from the longitudinal axis. The distal portion may include: a second straight section extending upward from the second curved section in a third direction oriented generally opposite to the first direction; a third curved section defining a third deformable preform curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0007] In some instances, a medical device system may include: an implantable medical device (IMD) comprising: a housing extending along a longitudinal axis from a proximal end to a distal end; electrodes mounted near the distal end of the housing; a fixation member comprising a base near the distal end of the housing and a plurality of teeth fixedly attached to each other at intervals around the periphery of the distal end of the housing; and a delivery tool comprising tubular sidewalls defining a lumen into which the IMD can be loaded, wherein the lumen has a distal opening through which the IMD can be deployed. Each of the plurality of teeth comprises: a proximal portion comprising: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment outward from the longitudinal axis; a first straight segment extending laterally from the first curved segment outward from the longitudinal axis in a second direction; and a second curved segment defining a second deformable preformed curvature and extending laterally from the first straight segment outward from the longitudinal axis; and a distal portion comprising a second straight segment extending upward from the second curved segment in a third direction oriented substantially opposite to the first direction; a third curved segment defining a third deformable preformed curvature and extending from the second straight segment; and a tip segment extending from the third curved segment toward the longitudinal axis and terminating at a free distal end.

[0008] In some instances, a method of forming a fixing member for an IMD may include: forming a base defining a longitudinal axis of the fixing member; and forming a plurality of teeth extending from the base and spaced apart from each other. Each of the plurality of teeth may include: a proximal portion comprising: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment and outwardly from the longitudinal axis; a first straight segment extending laterally from the first curved segment and outwardly from the longitudinal axis in a second direction; and a second curved segment defining a second deformable preformed curvature and extending laterally from the first straight segment and outwardly from the longitudinal axis; and a distal portion comprising a second straight segment extending upwardly from the second curved segment in a third direction oriented substantially opposite to the first direction; a third curved segment defining a third deformable preformed curvature and extending from the second straight segment; and a tip segment extending from the third curved segment toward the longitudinal axis and terminating at a free distal end.

[0009] The accompanying drawings and the following description illustrate one or more examples in detail. Other features, objects, and advantages will be apparent from the description and drawings, as well as from the claims. Attached Figure Description

[0010] Figure 1 This is a conceptual diagram illustrating part of an example medical device system configured to implant a relatively compact IMD at the target implantation site.

[0011] Figure 2A It is a conceptual diagram showing a relatively compact IMD (Integrated Device Manufacturing) plan view containing fixed components.

[0012] Figure 2B It is a diagram showing the implantation at the target site. Figure 2A A conceptual diagram of an IMD.

[0013] Figure 3A This is a conceptual diagram illustrating the elevation view of an example of a two-jointed fixed component.

[0014] Figure 3B It is a drawing Figure 3A A conceptual diagram of the end view of the two-jointed fixed component.

[0015] Figures 4A to 4E It is drawn before the curve is formed in the tooth. Figure 3A and 3B A conceptual diagram of the plan view of the teeth of the two-jointed fixed component.

[0016] Figure 5A and 5B This is a conceptual diagram illustrating a three-joint fixed component.

[0017] Figure 6 It is a conceptual diagram showing a partially cut-out plan view of a medical device system including a delivery vehicle and an IMD.

[0018] Figure 7A This is a conceptual diagram illustrating the spring-loaded configuration of a fixed component within the cavity of a delivery tool.

[0019] Figure 7B This is a conceptual diagram illustrating the initial release of the fixed component from the spring-loaded configuration.

[0020] Figure 7C It is a conceptual diagram illustrating the movement of teeth that cause initial penetration of tissue after the initial release of the fixed component.

[0021] Figure 7D This is a conceptual diagram illustrating the further movement of the fixing component when the portion of the tooth between the farthest curve and the next proximal curve reaches the distal end of the delivery tool.

[0022] Figure 7E It is a conceptual diagram illustrating the further movement of the fixed component as the proximal curve travels past the distal end of the delivery tool.

[0023] Figure 7F It is a concept diagram illustrating the final configuration of the fixed component after it has been moved.

[0024] Figure 8 This is a flowchart illustrating an example method for manufacturing fixed components. Detailed Implementation

[0025] This disclosure describes an IMD fixation component with improved flexibility, fixation, or both, to facilitate implantation of an IMD, such as a relatively compact IMD. An example fixation component for an IMD may include a base and a plurality of teeth. The plurality of teeth are configured to deploy with a target deployment stiffness to engage tissue at the target implantation site, while maintaining a target deflection stiffness after deployment to allow visualization of tissue engagement (e.g., via fluoroscopy). The base may define a longitudinal axis of the fixation component; for example, the proximal and distal ends of the IMD may be aligned along the longitudinal axis. The base may be fixedly attached to the IMD near the distal end. The plurality of teeth may be spaced apart from each other around the periphery of the distal end of the IMD and extend from the base. The shape of each respective tooth of the plurality of teeth can be selected to control each of the target deployment stiffness and the target deflection stiffness. For example, the shape of a corresponding tooth may include multiple preformed curves on the corresponding tooth, the curvature (e.g., radius) of each preformed curve on the corresponding tooth, the length of each preformed curve, the length of a straight segment between preformed curves, the width of the corresponding tooth or a segment thereof (e.g., one or more tapered portions), the thickness of the corresponding tooth, multiple cuts along the length of the corresponding tooth, the shape of the cuts, or any combination thereof.

[0026] Each of the plurality of teeth may include a proximal portion and a distal portion. The proximal portion may include a proximal segment and at least one curved segment. In some instances, the proximal portion may include a curved segment. In some instances, the proximal portion may include a first curved segment, a second curved segment, and a first straight segment between the first and second curved segments. The proximal segment is fixedly attached to the base and extends from the base in a first direction. For example, the first direction may be substantially parallel to the longitudinal axis (e.g., parallel or nearly parallel within the capabilities of fixed component manufacturing technology) or at an angle relative to the longitudinal axis. The first curved segment may define a first deformable preform curvature and extends laterally from the proximal segment outward from the longitudinal axis. The first straight segment extends laterally from the first curved segment outward in a second direction from the longitudinal axis. The second curved segment defines a second deformable preform curvature and extends laterally from the first straight segment outward from the longitudinal axis. The distal portion may include: a second straight section extending upward from the second curved section in a third direction oriented generally opposite to the first direction; a third curved section defining a third deformable preform curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0027] When deployed at the target implantation site, the tooth possesses deployment stiffness that allows it to penetrate the tissue at the target implantation site. By controlling the deployment stiffness, the tooth can have improved tissue fixation, including control over the tooth penetration depth and tissue engagement in the lateral direction. After deployment at the target implantation site, the tooth's deflection stiffness allows the clinician to confirm adequate fixation of the tooth in the patient's tissue. For example, a traction or drag test can be performed under fluoroscopy to confirm that the tooth has engaged with the tissue, thereby confirming the adequacy of the IMD implantation. The traction or drag test may involve the clinician pulling or dragging the deployed IMD and observing the tooth's movement to determine whether the tooth is engaged in the tissue, for example, a tooth embedded in the tissue deflects or bends as the deployed IMD is pulled or dragged. By controlling the deflection stiffness, the tooth can have improved flexibility, which allows the clinician to more easily confirm tissue engagement.

[0028] In this disclosure, example systems, devices, and techniques are described with reference to delivering an IMD to a target site within a patient's heart. However, it should be understood that the example systems, devices, and techniques of this disclosure are not limited to delivering an IMD to a target site within the heart. For example, the example systems, devices, and techniques described herein can be used to deliver other medical devices, such as drug delivery devices, sensing devices, neurostimulation devices, or medical leads, to other locations within a patient's body. In short, the example systems, devices, and techniques described herein can find useful applications in the delivery of a variety of implantable medical devices for the delivery of treatment or patient sensing to a patient.

[0029] Figure 1 This is a conceptual diagram illustrating a portion of an example medical device system 400 configured to implant a relatively compact implantable medical device 20 (“IMD20”) at a target implantation site 102. In some instances, such as Figure 1 As illustrated, the target implantation site 102 may include an appendage to the right atrial RA of the patient's heart 100. In some instances, the target implantation site 102 may include other parts of the heart 100 or other locations within the patient's body. The medical device system 400 may include a delivery tool 430 configured to receive and controllably deploy a relatively compact IMD 20. In some instances, a clinician may manipulate the medical device system 400 to the target implantation site 102. For example, with the IMD loaded therein, a clinician may guide the delivery tool 430 upward through the inferior vena cava (IVC) and into the right atrial RA. In some instances, other pathways or techniques may be used to guide the delivery tool 430 to other target implantation sites within the patient's body.

[0030] Figure 2AThis is a conceptual plan view illustrating a relatively compact IMD 20 including a fixing component 30. The IMD 20 includes a housing 205 extending along a longitudinal axis 2 from a proximal end 201 to a distal end 202. The housing 205 may be formed of a biocompatible and biostable metal, such as titanium. In some instances, the housing 205 may comprise a hermetically sealed housing. The IMD 20 may comprise any suitable size. In some instances, the outer diameter of the IMD 20 (e.g., the outer diameter of the housing 205) may be between about 10 French and about 30 French, for example, about 20 French.

[0031] The IMD 20 may include electronic circuitry and may include an electrode 206. The electronic circuitry includes one or more of sensing circuitry (e.g., for sensing cardiac signals), therapeutic delivery circuitry (e.g., for generating cardiac pacing pulses), and processing circuitry for controlling the function of the IMD 20. The electronic circuitry may be configured to generate and deliver electrical pulses to tissue near the electrode 206. The electrode 206 may be spaced apart from the distal end 202 of the housing 205, for example, coupled to the sensing and therapeutic delivery circuitry via a conductor of a sealed feedthrough assembly (not shown). In some instances, the IMD 20 includes a retaining member 209 fixedly attached to the proximal end 201 of the housing 205, wherein the retaining member 209 is configured to temporarily restrain the IMD 20 to a delivery tool, such as delivery tool 430. The housing 205 may be covered with an insulating layer, such as medical-grade polyurethane, parylene, or silicone. The insulating layer may define a second electrode 207, for example, by removing a portion of the insulating layer to expose a metallic surface of the housing 205. Electrode 206 can be used together with second electrode 207 for bipolar pacing and sensing.

[0032] The fixation component 30 includes a plurality of teeth 303 (“teeth 303”). Teeth 303 can be configured to maintain contact between the electrode 206 and tissue at the target implantation site (e.g., target implantation site 102). In some instances, the electrode 206 may be substantially flush longitudinally with the distal portion of the tooth 303 (e.g., relative to longitudinal axis 2), or at a distance “X” away from the tooth, said distance “X” may be up to about 2 millimeters (mm). The tooth 303 includes a proximal portion 33 and a distal portion 35. Each of the proximal portion 33 and the distal portion 35 may include one or more segments. For example, as... Figure 2A As illustrated, tooth 303 may comprise a first segment S1, a second segment S2, and a third segment S3. In other embodiments, tooth 303 may comprise fewer segments, such as two segments, or more segments, such as more than three segments. Each of the first segment S1, the second segment S2, and the third segment S3 may comprise an elastically deformable material pre-formed into curved segments and / or substantially straight segments. Figure 2AIn the illustrated example, the first segment S1 is fixedly attached to the distal end 202 of the device housing 205 and extends to the second segment S2 around the preformed curvature. The second segment S2 extends proximally along a relatively straight line to the third segment S3. The third segment S3 extends to the free distal end 352 around the preformed curvature.

[0033] The tooth 303 is configured to have a target deflection stiffness and a target deployment stiffness. The target deflection stiffness may include a measure of the resistance to a force applied to the IMD 20 in the proximal direction when the fixation member 30 engages with tissue at the target site 102. In some instances, the target deflection stiffness can be selected such that the tooth 303 can deflect by a predetermined amount, thereby enabling the tooth 303 to be visualized under fluoroscopy. In some instances, the target deflection stiffness may be in the range of about 0.2 N to about 0.8 N, for example, about 0.3 N to about 0.6 N. Deployment stiffness may be included in the force applied to the IMD 20 when the fixation member 30 engages with tissue at the target site 102. Figure 1 The target deployment stiffness is a measure of the force exerted by the tooth 303 as it moves from the deformed configuration to the undeformed configuration when the distal opening 403 of the target unfolds so that the free distal end 352 penetrates the comb-like muscle PM. In some instances, the target deployment stiffness can range from about 0.6 N to about 1.2 N.

[0034] Figure 2B This is a conceptual diagram illustrating an IMD 20 implanted at the target implantation site 102. The target implantation site 102 comprises a portion of the right atrial RA wall with a layered structure, comprising an inner layer of pectinate muscle PM and an outer layer of epicardial VP, the outer layer forming the epicardial surface. The IMD 20 is secured to the target implantation site 102 by teeth 303 of a fixation member 30 that passes through the layer of pectinate muscle PM without penetrating the epicardial VP. Perforation of the epicardial VP could lead to pericardial effusion. The teeth 303 are configured to be deployed via a delivery tool 430 ( Figure 1 The distal opening 403 of the spring-loaded release allows the free distal end 352 to pass through the comb-like muscle PM without penetrating the epicardium VP. It should be noted that alternative suitable implantation sites for the embodiments of the fixation member teeth described herein can be along any endocardial surface defined by the comb-like muscle PM.

[0035] Figure 3A This is a conceptual drawing of the elevation view of an example of a two-jointed fixed component 300. Figure 3B It is a drawing Figure 3AA conceptual diagram of the end view of the retaining member 300. Apart from the differences described herein, the two-jointed retaining member 300 may be identical or substantially similar to retaining member 30. For example, the two-jointed retaining member 300 includes teeth 303. Teeth 303 are depicted in a relaxed configuration, such as a configuration where no external force is applied to any part of the teeth 303. Retaining member 300 is referred to as a two-jointed retaining member because it has two curved sections that form two latches.

[0036] like Figure 3A As illustrated, the two-jointed retainer 300 includes a base 301 from which teeth 303 extend. The base 301 may define a longitudinal axis 3 of the two-jointed retainer 300. When the base 301 is mounted around the distal end 202 of the device housing 205 such that the periphery of the two-jointed retainer 300 extends around the electrode 206, the longitudinal axis 3 is substantially aligned with the longitudinal axis 2 of the IMD 20. Figure 2A ).

[0037] like Figure 3B As illustrated, teeth 303 are spaced apart from each other around the periphery of base 301. Base 301 may have an inner diameter (“id”) of about 0.20 inches (5.08 mm) and an outer diameter od of about 0.21 inches (5.334 mm). In some instances, the two articulated retaining members 300 may be mounted to the distal end 202 of device housing 205, for example, in the same or substantially similar manner as described in commonly assigned U.S. Patent No. 10,099,050B2 (filed January 19, 2017), which is incorporated herein by reference in its entirety. In some instances, the two articulated retaining members 300 may include separately formed teeth 303, which are individually mounted to the distal end 202 of device housing 205 (e.g., not integrated with base 301).

[0038] Teeth 330 can comprise any suitable, elastically deformable, biocompatible material. In some instances, teeth 303 can comprise a hyperelastic material, such as a nickel-titanium alloy. For example, the two-jointed fixation component 300 can be cut from a medical-grade nickel-titanium alloy tube conforming to the chemical, physical, mechanical, and metallurgical requirements of ASTM F2063 and having a wall thickness of approximately 0.005 inches (0.127 mm). In this way, teeth 303 can be integrally formed with the base 301, and each tooth in teeth 303 can have a constant thickness “t” of approximately 0.005 inches ± 0.001 inches (0.127 mm ± 0.0254 mm). In some instances, after cutting teeth 303, teeth 303 can be shaped into a pre-formed configuration by bending and holding teeth 303 while undergoing heat treatment according to methods known to those skilled in the art.

[0039] like Figure 3A As illustrated, each tooth in tooth 303 includes a proximal portion 33 (e.g., which may correspond to the first segment S1) and a distal portion 35 (e.g., which may correspond to the second segment S2 and the third segment S3). In some instances, the free distal end 352 may comprise any suitable shape, such as... Figure 3A The illustrated rounded or cut shape. The proximal segment 33-P is fixedly attached to the base 301. The proximal segment 33-P extends in a first direction d1. In some instances, the first direction d1 may be substantially parallel to the longitudinal axis 3. In some instances, the first direction d1 may be angled relative to the longitudinal axis 3, for example, between about 0 degrees and about 5 degrees. The curved segment 33-C may contain a spring-biased pre-shaped curvature. The curved segment 33-C extends laterally from the proximal segment 33-P outward from the longitudinal axis 3 to the distal portion 35. In some instances, the curved segment 33-C may contain a single radius ranging from about 0.06 inches (1.524 mm) to about 0.08 inches (2.032 mm), for example, about 0.067 inches ± 0.010 inches (1.7018 mm ± 0.254 mm). In some instances, the proximal portion 33 may contain more than one curved segment.

[0040] The distal portion 35 may include a proximal segment 35-P, a curved segment 35-C, and a tip segment 35-T. The proximal segment 35-P may be a substantially straight segment extending in the second direction d2 along a relatively straight line (dashed line). In some instances, the length of the proximal segment 35-P may range from about 0.075 inches (1.905 mm) to about 0.125 inches (3.175 mm), for example, about 0.100 inches ± 0.005 inches (2.54 mm ± 0.127 mm). The proximal segment 35-P may be oriented by the curved segment 33-C such that the second direction d2 is generally opposite to the first direction d1 and the relatively straight line intersects the longitudinal axis 3 at an acute angle θ. In some instances, the angle θ is between about 30 degrees and about 60 degrees, for example, about 45 degrees. The curved segment 35-C may include a deformable preformed curvature. The curved section 35-C extends rearward from the proximal section 35-P (in direction d2) toward the longitudinal axis 3 to the tip section 35-T. In some instances, the curved section 35-C, when undeformed, is defined by a single radius ranging from about 0.045 inches (1.143 mm) to about 0.055 inches (1.397 mm), for example, about 0.05 inches ± 0.010 inches. The tip section 35-T may comprise a substantially straight segment extending from the curved section 35-C to the free distal end 352 in the third direction d3. In some instances, the length of each tip section 35-T may range from about 0.055 inches (1.397 mm) to about 0.075 inches (1.905 mm), for example, about 0.064 inches ± 0.005 inches (1.6256 mm ± 0.127 mm). The tip segment 35-T is shown as extending toward the longitudinal axis 3 when the curved segment 35-C is oriented in its undeformed state, such that the tip segment 35-T and the proximal segment 35-P are shown as forming an angle. In some instances, angle It can be greater than or equal to about 90 degrees, for example, in the range from about 90 degrees to about 120 degrees.

[0041] The shape (e.g., undeformed configuration) and width of each tooth 303, and in some instances, the hyperelastic stiffness properties of the nickel-titanium alloy, provide sufficient spring force and structural stiffness to engage tissue upon unfolding by the delivery tool 430 to secure the IMD 20 at the implantation site, as described in more detail below. Reference Figure 3A Each tooth 303 has a width “W” ranging from about 0.020 inches (0.508 mm) to about 0.035 inches (0.889 mm), for example, about 0.031 inches (0.7874 mm). In some instances, the width of the tooth 303 can be selected to provide a radiopaque density that facilitates fluorescence fluoroscopic visualization during and after the implantation procedure.

[0042] Figures 4A to 4E It is drawn before the curve is formed in the tooth. Figure 3A and 3B The diagram shows a conceptual plan view of the teeth 450A-450E (collectively referred to as teeth 450) of the two-jointed fixing component 300. Apart from the differences described herein, teeth 450 can be compared with those referenced above. Figures 2A to 3B The teeth 303 discussed are the same or substantially similar. For example, tooth 450 may include a proximal portion 452 extending from base 451 and a distal portion 454 extending from proximal portion 452. As indicated by the dashed lines indicating the approximate boundaries of the segments, proximal portion 452 may include proximal segment 456 and curved segment 458, and distal portion 454 may include proximal segment 460, curved segment 462 and tip segment 464.

[0043] like Figure 4A As illustrated, tooth 450A may have a substantially constant width W along its length L (e.g., constant or nearly constant within the limits of common manufacturing tolerances). For example, the proximal portion 452A, which includes the curved section 458A, and the distal portion 454A, which includes the proximal portion 460A, the curved section 462A, and the tip section 464A, may have substantially constant widths. In some instances, the proximal portion 456A may include a fillet 457A extending from the base 451A. The fillet 457A may reduce stress concentration at the junction of the proximal portion 456A and the base 451A. The width W and length L of tooth 450A may be the same as or substantially similar to those of tooth 303 discussed above.

[0044] like Figure 4B As illustrated, the curved section 458B of tooth 450B may include a tapered portion 459B. The tapered portion 459B includes a proximal width W1, a middle (central) width W2, and a distal width W3. In some instances, W1 and W3 may be the same or substantially similar, for example, about 0.030 inches (0.762 mm), and W2 may be about 0.025 inches (0.635 mm). Although illustrated as including three widths, in some instances, the tapered portion 459B may include multiple tapered sections, each with its own maximum width and its own minimum width. In some instances, the tapered portion 459B may increase the curvature of the curved section 458B relative to the unaltered curved section (e.g., Figure 4AThe flexibility of the illustrated bending segment 458A. By increasing the flexibility of the bending segment 458B, the tooth 450B, after pre-forming the bending segment 458B as discussed above, can have increased deflection stiffness compared to the unaltered bending segment. In some instances, the distal portion 454B (e.g., the proximal segment 460B, the bending segment 462B, and the tip 464B with a free distal end 466B) may not include the tapered portion. By not including the tapered portion, the tooth 450B can have the same or substantially the same unfolding stiffness compared to a tooth with an unaltered proximal portion (e.g., tooth 450A). In this way, the tooth 450 can include one or more tapered portions to selectively control unfolding stiffness, deflection stiffness, or both.

[0045] For example, such as Figure 4C As illustrated, tooth 450C comprises multiple cones. The proximal segment 456C may include a fillet 457C extending from the base 451C. A curved segment 458C may extend from the proximal segment 456C and includes a tapered portion 459C having a proximal width W1, a mid-width W2, and a distal width W3. The proximal segment 460C of the distal portion 454C may extend from the curved segment 458C and includes a tapered portion 461C having a proximal width W3, a mid-width W4, and a distal width W5. The proximal segment 460C of the distal portion 454C may extend from the curved segment 458C and includes a tapered portion 461C having a proximal width W3, a mid-width W4, and a distal width W5. The curved section 462C of the distal portion 454C can extend from the proximal section 462C and includes a tapered portion 463C having a proximal width W5, a middle width W6, and a distal width W7. For example... Figure 4C Each of the cones 459C, 461C, and 463C illustrated may contain a unique shape. For example, the unique shape of each cone portion may be configured to have a target flexibility after the preformed tooth 450C, such that the tooth 450C has a target deflection stiffness and unfolding stiffness.

[0046] In some instances, tooth 450 may include cuts, engravings, embossing, or other variations in tooth 450 thickness, rather than a tapered portion. For example, as... Figure 4D As illustrated, tooth 450D includes a cutout 458D having a width W8 extending with a length L2 along a curved segment 458C of the proximal portion 452D, rather than a tapered portion. In some instances, cutout 458D may be configured relative to the unaltered curved segment (e.g., Figure 4A The bending section 458A shown in the figure increases the flexibility of the bending section 458D. By increasing the flexibility of the bending section 458D, the tooth 450D can have increased deflection stiffness after the pre-formed bending section 458D as discussed above, compared with the unaltered bending section.

[0047] like Figure 4E As illustrated, tooth 450E includes multiple cuts 459E, 451E, and 453E. Similarly, as referenced above... Figure 4C Each of the cuts 459E, 451E, and 453E discussed may contain a unique shape and location configured to produce the target flexibility of tooth 450E (e.g., after preformed tooth 450C) such that tooth 450C has target deflection stiffness and target unfolding stiffness.

[0048] In some instances, the teeth of the fixed component may contain more than two curved sections to generate target deflection stiffness and target deployment stiffness. Figure 5A and 5B This is a conceptual diagram illustrating an example of a three-joint fixation component 500. Aside from the differences described herein, the three-joint fixation component 500 can be compared with the one referenced above. Figures 2A to 4E The fixation member 30 discussed is the same as or substantially similar to the two-joint fixation member 300. For example, the three-joint fixation member 500 includes a base 501 from which teeth 503 extend and are spaced apart from each other around the periphery of the base. The base 501 may define a longitudinal axis 502 of the three-joint fixation member 500, which in some instances may be aligned substantially with the longitudinal axis 2 of the IMD 20. Figure 2A ).

[0049] like Figure 5A As illustrated, each tooth of tooth 503 includes a proximal portion 533 and a distal portion 535 terminating at a free distal end 552. A proximal segment 510 of the proximal portion 533 is fixedly attached to the base 501. The proximal portion 533 may include a proximal segment 510, a first curved segment 512, a first straight segment 514, and a second curved segment 516, the first straight segment 514 being located between the first curved segment 512 and the second curved segment 516. The size and shape of each of the proximal segment 510, the first curved segment 512, the first straight segment 514, and the second curved segment 516 can be configured such that tooth 503 can possess target deflection stiffness and target deployment stiffness.

[0050] The proximal segment 510 extends in a first direction d1. In some instances, the first direction d1 may be substantially parallel to the longitudinal axis 502. In some instances, the first direction d1 may be at an angle relative to the longitudinal axis 502, for example, between about 0 degrees and about 5 degrees.

[0051] The first bending section 512 may include a spring-biased preformed curvature. The first bending section 512 extends laterally from the proximal section 510 outward from the longitudinal axis 502 to the first straight section 514. In some instances, the first bending section 512 may contain a single radius ranging from about 0.06 inches (1.524 mm) to about 0.08 inches (2.032 mm), for example, 0.067 inches ± 0.010 inches (1.7018 mm ± 0.254 mm).

[0052] The first straight segment 514 may be a substantially straight segment extending along a relatively straight line in the second direction d2 to the second curved segment 516. In some instances, the second direction d2 may be perpendicular to the longitudinal axis 502. In some instances, the length of the first straight segment 514 may range from about 0.035 inches (0.889 mm) to about 0.045 inches (1.143 mm), for example, about 0.04 inches (1.016 mm). The first straight segment 514 may be oriented away from the longitudinal axis 502 by the first curved segment 512 when undisturbed, such that the proximal segment 510 and the first straight segment 514 form an angle. In some instances, angle It can be in the range of approximately 75 degrees to approximately 105 degrees, for example, approximately 90 degrees.

[0053] The second bending section 516 may include a spring-biased preformed curvature. The second bending section 516 extends laterally from the proximal section 510 outward from the longitudinal axis 502 to the distal portion 535 of the second straight section 518. In some instances, the second bending section 516 may contain a single radius ranging from about 0.06 inches (1.524 mm) to about 0.08 inches (2.032 mm), for example, 0.067 inches ± 0.010 inches (1.7018 mm ± 0.254 mm).

[0054] The distal portion 535 may include a second straight section 518, a third curved section 520, and a tip section 522. The size and shape of the second straight section 518 and / or the third curved section 520 may be configured such that the tooth 503 can have target deflection stiffness, target deployment stiffness, or both.

[0055] As discussed above, in some instances, the target deflection stiffness can be selected such that tooth 503 can deflect by a predetermined amount, thereby enabling tooth 503 to be visualized under fluorescence. In some instances, the target deflection stiffness can be in the range of about 0.2 N to about 0.8 N, for example, about 0.3 N to about 0.6 N. The unfolding stiffness can be a measure of the force exerted by tooth 503 as it moves from the deformed configuration to the undeformed configuration when the fixed component unfolds from the distal opening of the delivery tool such that the free distal end 524 penetrates the comb-like muscle PM. In some instances, the target unfolding stiffness can be in the range of about 0.6 N to about 1.2 N.

[0056] The second straight segment 518 may be comprised of a substantially straight segment extending along a relatively straight line (dashed line) on a third direction d3. In some instances, the length of the second straight segment 518 may range from approximately 0.075 inches (1.905 mm) to 0.125 inches (3.175 mm), for example, 0.100 inches ± 0.005 inches (2.54 mm ± 0.127 mm). The second straight segment 518 may be oriented by the second curved segment 516 when undeformed, such that the first straight segment 514 and the second straight segment 518 form an angle. In some instances, angle It can be in the range of approximately 120 degrees to approximately 150 degrees, for example, approximately 135 degrees.

[0057] The third bending section 520 may include a deformable preformed curvature. The third bending section 520 extends rearward from the second straight section 518 (in direction d3) toward the longitudinal axis 502 to the tip section 522. In some instances, the third bending section 520, when undeformed, is defined by a single radius in the range of about 0.045 inches (1.143 mm) to about 0.055 inches (1.397 mm), for example, 0.05 inches ± 0.010 inches (1.27 mm ± 0.254 mm).

[0058] The tip segment 522 may comprise a substantially straight segment extending in the fourth direction d4 from the third curved segment 520 to the free distal end 524. In some instances, the length of each tip segment 522 may range from about 0.045 inches (1.143 mm) to about 0.055 inches (1.397 mm), for example, about 0.05 inches ± 0.010 inches (1.27 mm ± 0.254 mm). The tip segment 522 is shown as being oriented by the third curved segment 520 in its undeformed state toward the longitudinal axis 502, such that the tip segment 522 and the second straight segment 518 are shown enclosing an angle. In some instances, angle It can be greater than or equal to about 90 degrees, for example, in the range from about 90 degrees to about 120 degrees.

[0059] As referenced above Figures 2A to 4E The shaped configuration and width of each tooth (e.g., tooth 503), as well as the hyperelastic stiffness of the nickel-titanium alloy in some instances, enable each of the teeth 530 to generate sufficient spring force and structural stiffness to engage tissue when unfolded by the delivery tool 430 in order to secure the IMD 20 at the implantation site, as described in more detail below.

[0060] Figure 6 This is a conceptual plan view showing a partial cross-sectional section of a medical device system 400 including a delivery tool 430 and an IMD 20. For illustrative purposes, the distal end of the delivery tool 430 is enlarged relative to the handle 410. Additionally, although the medical device system 400 is referenced... Figure 2A and 2B The fixed component 30 is described in the illustration, but in other instances, the medical device system 400 may include other fixed components, such as those shown in the references. Figure 3A and 3B The described two-joint fixation component 300 or reference Figure 5A and 5B The illustrated three-joint fixation component 500.

[0061] During use, the IMD 20 is loaded into a delivery tool 430 for deployment to a target implantation site (e.g., target implantation site 102). The delivery tool 430 includes a handle 410, an elongated outer member 430, and an elongated inner member 420 extending within a lumen 435 of the outer member 430. The inner member 420 includes a distal end 422 configured to engage the IMD 20 by abutting a proximal end 201 of the housing 205 (e.g., as shown in a cross-section). The entire IMD 20 can be loaded within a tubular sidewall 432 defining a distal portion of the outer member lumen 435, for example, by pulling the IMD 20 to introduce the proximal end 201 of the housing into a distal opening 403 of the lumen. In some instances, when the IMD20 is loaded into the lumen 435, the inner surface 42 of the tubular sidewall 432 engages the teeth 303 of the fixing member 30 to deform the teeth 303 (e.g., Figure 3A (as indicated by arrow L), and then each tooth 303 of the loaded IMD 20 is held in a deformable configuration, such as a spring-loaded configuration.

[0062] Further reference Figure 6The proximal end of the outer member 430 is connected to the control member 412 of the handle 410, allowing the entire outer member 430 to be moved relative to the inner member 420, for example via the control member 412. This allows the clinician to retract the outer member 430 relative to the IMD 20 and the inner member 420 along arrow W after positioning the medical device system 400 near the target implantation site, to deploy the IMD 20 through the distal opening 403. The clinician can position the medical device system 400 by advancing the delivery tool 403 through the patient's venous system, for example, from the femoral vein entry site and upward through the inferior vena cava (IVC). Figure 1 The delivery tool 430 may include an articulated feature to facilitate navigation of its distal portion. For example, the inner member 420 of the delivery tool 430 may include a drawstring assembly (not shown) integrated therein and coupled to another control member 411 of the handle 410, which, when moved along arrow A, causes the inner member 420 and the outer member 430 to bend along their distal portions. When the outer member 430 is in Figure 6 In the position shown, the length of the outer member 430 between the handle 410 and the distal opening 403 can be, for example, between about 103 cm and about 107 cm, to reach the right atrium RA from the femoral entry site. Suitable configurational details of a delivery tool similar to the delivery tool 430 are described in co-pending and co-assigned U.S. Patent 9,526,522 to Wood et al., which is incorporated herein by reference in its entirety.

[0063] According to some methods, once the clinician has advanced the medical device system 400 to the target implantation site 102 ( Figure 1 This allows the distal opening 403 to be adjacent to the pectinate muscle PM at the target implantation site. Figure 2B The clinician can then move the control member 412 along arrow B to retract the external member 430 relative to the IMD 20, thereby releasing the spring load on the three-joint fixation member 500, allowing the teeth 303 to engage with the pectinate muscle PM to secure the IMD 20 at the implantation site. Figure 2B As illustrated. However, it should be noted that, according to alternative embodiments and methods, the delivery tool 430 may be configured to allow a clinician to advance the internal member 420 relative to the external member 430 to push out the distal opening 403 of the IMD 20 for deployment.

[0064] Figures 7A to 7F This is a conceptual diagram illustrating the sequence of positions and / or configurations corresponding to the release of the fixed components described above. (Although references are available...) Figure 2A and 2BThe described fixing component 30 is illustrated, but in other instances, the delivery tool 430 may be configured to release other fixing components, such as those described in reference to [reference needed]. Figure 3A and 3B The described two-joint fixation component 300 or reference Figure 5A and 5B The illustrated three-joint fixation component 500. Figure 7A This is a conceptual diagram illustrating the spring-loaded configuration of a fixed component within the cavity of a delivery tool. Figure 7A The maximum deformation of tooth 303 is illustrated when it is held in a spring-loaded configuration by engagement with the inner surface 42 of the tubular sidewall 432 of the outer member via the free distal end 352. In some instances, the proximal portion 33 becomes relatively straight. In some instances, the location of the maximum principal strain along each tooth 303 is relatively adjacent to the base 301 (indicated by the dashed circle). In some instances, the length and associated angle of the tip segment 35-T are shown. (as referenced above) Figure 3A The described features help prevent the deformed teeth 303 from contacting each other within the lumen 435, and help prevent the free distal end 352 from being pulled proximally along arrow P when the outer member 430 is retracted to release the spring load on the teeth 303.

[0065] Figure 7A The diagram further illustrates the tip section 35-T extending away from axis 3 at an acute angle δ, preferably in the range of about 45 degrees to about 75 degrees, for the initial release of the spring load on each tooth 303. For example, Figure 7B This is a conceptual diagram illustrating the initial release of the fixed component from the spring-loaded configuration. When the outer member 430 retracts, the tip section 35-T extends through the distal opening of the sidewall 432.

[0066] Figure 7C This is a conceptual diagram illustrating the movement of the teeth that cause initial tissue penetration after the initial release of the fixation component. For example, once the free distal end 352 is released from its engagement with the inner surface 42 to unfold into the tissue at the implantation site, the spring force of the proximal portion 33 and the pre-shaped curvature of the curved segment 35-C cause the tip segment 35-T to immediately rotate away from axis 3 to an angle π close to 90 degrees, such that the tip segment 35-T is oriented approximately perpendicular to axis 3 for initial penetration of the comb-like muscle PM. Thus, the free distal end 352 of each tooth unfolds in a direction toward the comb-like muscle PM, which ultimately prevents the tooth 303 from penetrating the underlying epicardium VP (reference). Figure 2B ).

[0067] Figures 7D to 7F The subsequent movement of tooth 303, driven by the release of the proximal portion 33 from the spring-loaded configuration, is illustrated. Figure 7DThis is a conceptual diagram illustrating the further movement of the fixing component as the portion of the tooth between the distal curve and the next proximal curve reaches the distal end of the delivery tool. When each tooth in tooth 303... Figure 7C The position shown in the drawing moves to Figure 7D In the position shown, the free distal end 352 can travel substantially transversely to the longitudinal axis 3, thereby penetrating other tissues. Figure 7E It is a conceptual diagram illustrating the further movement of the fixed component as the proximal curve travels past the distal end of the delivery tool. Figure 7F This is a conceptual diagram illustrating the final configuration of the moved fixed component. For example... Figures 7D to 7F As illustrated, the release of the proximal portion 33 causes the free distal end 352 to curl posteriorly toward the longitudinal axis 3, so that after penetrating the pectinate muscle PM at the first position P1, the tip segment 35-T can penetrate the pectinate muscle PM in the opposite direction at the second position P2, allowing the IMD 20 to be securely fixed at the implantation site, as shown. Figure 2B As shown in the drawing.

[0068] The configuration of the distal portion 35, including, for example, the lengths of the proximal segment 35-P and the tip segment 35-T, and the pre-shaped curvature of the curved segment 35-C, provides structural stiffness and reaches each tooth 303, said structural stiffness being sufficient to deform the free distal end 352 and subsequently penetrate the comb-like muscle PM, such as... Figure 2B As shown, but not enough to penetrate the epicardium VP. Even if the clinician eventually advances the medical device system 400 into the target implantation site 102, such that the distal opening 403 of the delivery tool 430 is adjacent to the epicardium VP between the folds of the pectinate muscle PM, the free distal end 352 will not penetrate the epicardium VP due to sufficient rigidity, according to the configuration of the tooth 303. Therefore, the tip segment 35-T of the distal portion 35 of the tooth is laterally redirected toward the pectinate muscle PM.

[0069] The fixed components described herein can be manufactured using any suitable technology. Figure 8 This is a flowchart illustrating an example method for manufacturing a three-joint fixed component 500. Although Figure 8 The techniques illustrated are for reference only. Figure 5A and 5B The illustrated three-joint fixation component 500 is used for description, but the technology described can be used to manufacture other fixation components, for example, referencing Figure 2A , 2B The fixing component 30 described in 6 and 7A to 7F, and referenced Figure 3A and 3B The aforementioned two-joint fixation component 300. Alternatively, the fixation component 30 and / or the two-joint fixation component 300 may be manufactured using other techniques.

[0070] Figure 8 The illustrated technique includes forming a base 501 that defines a longitudinal axis 502 of a fixing member 500. In some instances, forming the base 501 may include cutting a tube, such as a metal tube, a nickel-titanium alloy tube, or a stainless steel tube, to define the base 501. Forming the base 501 may include pre-processing or post-processing steps, such as grinding, coating, heat-treating, or polishing the substrate defining the base 501.

[0071] Figure 8 The illustrated technique also includes forming teeth 503 extending from and spaced apart from the base 501. In some instances, the base 501 and teeth 503 may be integrally formed. For example, the base 501 and teeth 503 may be integrally formed from a tube, such as a metal tube, a nickel-titanium alloy tube, or a stainless steel tube. In some instances, forming the base 501 and teeth 503 from a single tube may include removing material from the single tube to define the base 501 and teeth 503. In some instances, removing material from the single tube may include one or more of machining, chemical etching, laser etching, stamping, or waterjet cutting. In some instances, forming teeth 503 may include forming one or more cones on one or more of a plurality of teeth. For example, forming one or more cones may include any of the above techniques for removing material from a single tube. In some instances, one or more cones may be formed simultaneously with removing material from a single tube.

[0072] In some instances, forming teeth 503 may involve bending each tooth of teeth 503 to define a first bending segment 512, a second bending segment 516, and a third bending segment 520. In some instances, each curve and / or each tooth of teeth 503 may be bent individually or simultaneously, for example, by using a jig configured to bend one or more curves on one or more teeth 503. After bending (and holding) teeth 503 in a bent configuration, forming teeth 503 may also involve heat-treating the bent teeth 503 such that the plurality of teeth retain the bent configuration. For example, heat-treating the bent teeth 503 may cause the microstructure of the material of teeth 503 to present a configuration such that the resting state of teeth 503 (e.g., without external force applied) is the bent configuration.

[0073] The following terms describe the exemplary subject matter of this disclosure.

[0074] Clause 1. A fixation component for an implantable medical device (IMD), comprising: a base defining a longitudinal axis of the fixation component, wherein the base is fixedly attached to the IMD, the IMD having a proximal end and a distal end aligned along the longitudinal axis; and a plurality of teeth extending from the base and spaced apart from each other, each of the plurality of teeth comprising: a proximal portion comprising: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment outward from the longitudinal axis; and a first straight segment. The first straight section extends laterally from the first curved section and outwardly from the longitudinal axis in a second direction; and a second curved section defines a second deformable preform curvature and extends laterally from the first straight section and outwardly from the longitudinal axis; and a distal portion comprising: a second straight section extending upwardly from the second curved section in a third direction oriented substantially opposite to the first direction; a third curved section defining a third deformable preform curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0075] Clause 2. The fixing component as described in Clause 1, wherein the proximal portion is configured to have a deflection stiffness of less than about 0.6 Newtons (N).

[0076] Clause 3. The fixing component according to Clause 1 or 2, wherein the proximal portion is configured to have a deployment stiffness greater than about 0.6 N.

[0077] Clause 4. The fixing member according to any one of Clauses 1 to 3, wherein, in the undeformed configuration, the first bending section is defined by the radius of the first deformable preformed curvature in the range of about 1.524 mm to about 2.032 mm.

[0078] Clause 5. The fixing member according to any one of Clauses 1 to 4, wherein, when in an undeformed configuration, the second bending section is defined by the radius of the second deformable preformed curvature in the range of 1.524 mm to about 2.032 mm.

[0079] Clause 6. The fixing member according to any one of Clauses 1 to 5, wherein, when in an undeformed configuration, the third bending section is defined by the radius of the third deformable preformed curvature in the range of about 1.143 mm to about 1.397 mm.

[0080] Clause 7. The fixing member according to any one of Clauses 1 to 6, wherein the first straight section has a length in the range of about 0.889 mm to about 1.143 mm.

[0081] Clause 8. The fixing member according to any one of Clauses 1 to 7, wherein the second straight section has a length ranging from about 1.905 mm to about 3.175 mm.

[0082] Clause 9. The fixing component according to any one of Clauses 1 to 8, wherein the first straight section and the second straight section enclose an angle in the range of about 120 degrees to about 150 degrees.

[0083] Clause 10. The fixing member according to any one of Clauses 1 to 9, wherein the tip section has a length ranging from about 1.143 mm to about 1.397 mm.

[0084] Clause 11. The fixing member according to any one of Clauses 1 to 10, wherein the third curved section, when undeformed, orients the tip section at an angle ranging from about 90 degrees to about 120 degrees with the second straight section.

[0085] Clause 12. The fixing component according to any one of Clauses 1 to 11, wherein at least one of the first curved section or the second curved section includes a tapered portion with a width less than about 0.762 mm.

[0086] Clause 13. The fixing component according to any one of Clauses 1 to 12, wherein at least one of the first straight section, the second straight section, or the tip section includes a tapered portion with a width less than about 0.762 mm.

[0087] Clause 14. The fixing member according to any one of Clauses 1 to 13, wherein the tapered portion includes a proximal portion having a width of about 0.762 mm, a middle portion having a width of about 0.635 mm, and a distal portion having a width of about 0.762 mm.

[0088] Clause 15. The fixing member according to any one of Clauses 1 to 14, wherein the tapered portion includes a variation in the width of the teeth of at least about 0.127 mm.

[0089] Clause 16. The fixing member according to any one of Clauses 1 to 15, wherein the tapered portion includes a cut, and wherein the width includes the tooth minus the width of the widest portion of the cut.

[0090] Clause 17. A fixation member for an implantable medical device (IMD), comprising: a base defining a longitudinal axis of the fixation member, wherein the base is fixedly attached to the IMD, the IMD having a proximal end and a distal end aligned along the longitudinal axis; and a plurality of teeth extending from the base and spaced apart from each other, each of the plurality of teeth comprising: a proximal portion comprising: a proximal segment fixedly attached to the base and extending in a first direction substantially parallel to the longitudinal axis; and a first curved segment, wherein... The first bending segment extends laterally from the proximal segment outward from the longitudinal axis, wherein the bending segment is configured to provide a deflection stiffness of less than about 0.6 Newtons; the distal portion includes: a second proximal segment extending from the first bending segment in a second direction oriented generally opposite to the first direction; a second bending segment having a deformable preformed curve and extending from the second proximal segment; and a tip segment extending from the second bending segment toward the longitudinal axis and terminating at a free distal end.

[0091] Clause 18. The fixing member as described in Clause 17, wherein the first bend includes a width equal to or less than 0.635 mm.

[0092] Clause 19. The fixing member according to Clause 17 or 18, wherein at least a portion of a respective tooth of the plurality of teeth includes a cone.

[0093] Clause 20. The fixing component according to Clause 19, wherein the portion of the corresponding tooth includes the second proximal section.

[0094] Clause 21. The fixing member according to Clause 19 or 20, wherein the cone includes a proximal portion having a width of about 0.762 mm, a middle portion having a width of about 0.635 mm, and a distal portion having a width of about 0.762 mm.

[0095] Clause 22. The fixing member according to any one of Clauses 19 to 21, wherein the cone includes a variation of at least about 0.127 mm in the width of the teeth.

[0096] Clause 23. The fixing member according to any one of Clauses 17 to 22, wherein the first bending section is defined by a single radius, said radius being between about 1.524 mm and about 2.032 mm.

[0097] Clause 24. The fixing member according to any one of Clauses 17 to 23, wherein the first bending section comprises a first deformable preformed bending section and a second deformable preformed bending section.

[0098] Clause 25. The fixing member according to Clause 24, wherein the first bending section further includes a straight section extending between the first deformable preformed bending section and the second deformable preformed bending section.

[0099] Clause 26. The fixing member according to Clause 24 or 25, wherein the deflection stiffness of the first bending section is defined by a first radius of the first deformable preformed curvature in its undeformed configuration, a second radius of the second deformable preformed curvature in its undeformed configuration, and the length of the straight section extending therebetween.

[0100] Clause 27. An implantable medical device (IMD) comprising: a housing extending from a proximal end to a distal end along a longitudinal axis; an electrode mounted near the distal end of the housing; and a fixation member including a base near the distal end of the housing and a plurality of teeth fixedly attached to each other at intervals around the periphery of the distal end of the housing, each of the plurality of teeth including: a proximal portion comprising: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment outward from the longitudinal axis; a first straight segment; and a first straight segment. The system comprises: a line segment, the first straight segment extending laterally from the first curved segment and outwardly from the longitudinal axis in a second direction; a second curved segment defining a second deformable preform curvature and extending laterally from the first straight segment and outwardly from the longitudinal axis; and a distal portion comprising: a second straight segment extending upwardly from the second curved segment in a third direction oriented substantially opposite to the first direction; a third curved segment defining a third deformable preform curvature and extending from the second straight segment; and a tip segment extending from the third curved segment toward the longitudinal axis and terminating at a free distal end.

[0101] Clause 28. The IMD as described in Clause 27, wherein the proximal portion is configured to have a deflection stiffness of at least less than 0.6 N.

[0102] Clause 29. The IMD as described in Clause 27 or 28, wherein the proximal portion is configured to have a deployment stiffness of at least 0.6 N.

[0103] Clause 30. A medical device system comprising: an implantable medical device (IMD), the IMD including: a housing extending from a proximal end to a distal end along a longitudinal axis; electrodes mounted near the distal end of the housing; and a fixation member including a base near the distal end of the housing and a plurality of teeth fixedly attached to each other at intervals around the periphery of the distal end of the housing; and a delivery tool including a tubular sidewall defining a lumen into which the IMD can be loaded, wherein the lumen has a distal opening through which the IMD can be deployed, wherein each of the plurality of teeth includes: a proximal portion including: a proximal segment fixedly attached to the base and extending from the base in a first direction; and a first curved segment, the... A first curved section defines a first deformable preformed curvature and extends laterally from the proximal section outward from the longitudinal axis; a first straight section extends laterally from the first curved section outward from the longitudinal axis in a second direction; a second curved section defines a second deformable preformed curvature and extends laterally from the first straight section outward from the longitudinal axis; and a distal portion comprising: a second straight section extending upward from the second curved section in a third direction oriented substantially opposite to the first direction; a third curved section defining a third deformable preformed curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0104] Clause 31. The medical device system according to Clause 30, wherein the proximal portion is configured to have a deflection stiffness of at least less than 0.6 N.

[0105] Clause 32. The medical device system according to Clause 30 or 31, wherein the proximal portion is configured to have a deployment stiffness of at least 0.6 N.

[0106] Clause 33. A medical device system according to any one of Clauses 30 to 32, wherein, when the IMD is loaded into the lumen of the delivery tool, the free distal end of each tooth of the retaining member engages an inner surface of the tubular sidewall near the distal opening of the delivery tool to hold at least one of the first, second, or third curved segments of each of the plurality of teeth in a spring-loaded configuration, in which: each tip segment extends away from the longitudinal axis at an acute angle in the range of about 45 degrees to about 75 degrees to unfold the corresponding free distal end from the distal opening; and upon unfolding, in response to the initial release of the spring-loaded configuration of at least one of the first, second, or third curved segments of each of the plurality of teeth, each tip segment rotates away from the longitudinal axis to an angle approaching about 90 degrees relative to the longitudinal axis.

[0107] Clause 34. A method of forming a fixing member for an IMD, comprising: forming a base defining a longitudinal axis of the fixing member; and forming a plurality of teeth extending from the base and spaced apart from each other, each of the plurality of teeth comprising: a proximal portion comprising: a proximal segment fixedly attached to the base and extending from the base in a first direction; a first curved segment defining a first deformable preformed curvature and extending laterally from the proximal segment and outward from the longitudinal axis; and a first straight segment extending laterally from the first curved segment and outward from the base. The longitudinal axis extends outward in a second direction; and a second curved section defines a second deformable preform curvature and extends laterally from the first straight section, outward from the longitudinal axis; and a distal portion comprising: a second straight section extending upward from the second curved section in a third direction oriented generally opposite to the first direction; a third curved section defining a third deformable preform curvature and extending from the second straight section; and a tip section extending from the third curved section toward the longitudinal axis and terminating at a free distal end.

[0108] Clause 35. The method according to Clause 34, wherein the base and the plurality of teeth are integrally formed by the tube by removing material from the tube to define the base and the plurality of teeth.

[0109] Clause 36. The method according to Clause 34 or 35, wherein forming the plurality of teeth comprises: bending each of the plurality of teeth to define a first bending segment, a second bending segment, and a third bending segment; and heat-treating the bent plurality of teeth to maintain the bent configuration.

[0110] Clause 37. The method according to any one of Clauses 34 to 36, wherein the method comprises forming one or more cones on one or more of the plurality of teeth.

[0111] Various examples of this 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.

Claims

1. A fixation component for an implantable medical device, comprising: a base defining a longitudinal axis of the fixation component, wherein the base is fixedly attached to the implantable medical device having a proximal end and a distal end aligned along the longitudinal axis; and a plurality of tines extending from the base and spaced apart from one another, each tine of the plurality of tines comprising: a proximal portion comprising: a proximal segment fixedly attached to the base and extending therefrom in a first direction; a first curved segment defining a first deformable pre-shaped curvature and extending laterally, outward from the longitudinal axis, from the proximal segment; a first straight segment extending laterally, outward from the longitudinal axis in a second direction, from the first curved segment; and a second curved segment defining a second deformable pre-shaped curvature and extending laterally, outward from the longitudinal axis, from the first straight segment; and a distal portion comprising: a second straight segment extending in a third direction oriented generally opposite the first direction, from the second curved segment; a third curved segment defining a third deformable pre-shaped curvature and extending from the second straight segment; and a tip segment extending toward the longitudinal axis from the third curved segment and terminating at a free distal end; wherein the first direction is parallel to the longitudinal axis of the base and the second direction is perpendicular to the longitudinal axis of the base.

2. The stationary component of claim 1, wherein, the proximal portion is configured to have a deflection stiffness of less than about 0.6 Newtons (N).

3. The stationary component according to claim 1 or 2, wherein the proximal portion is configured to have a deployment stiffness of greater than about 0.6 N.

4. The stationary component according to claim 1 or 2, wherein the first curved segment, when in an undeformed configuration, is defined by a radius of the first deformable pre-shaped curvature in a range from about 1.524 millimeters (mm) to about 2.032 mm.

5. The stationary component according to claim 1 or 2, wherein the second curved segment, when in an undeformed configuration, is defined by a radius of the second deformable pre-shaped curvature in a range from 1.524 mm to about 2.032 mm.

6. The stationary component of claim 1 or 2, wherein, the third curved segment, when in an undeformed configuration, is defined by a radius of the third deformable pre-shaped curvature in a range from about 1.143 mm to about 1.397 mm.

7. The stationary component of claim 1 or 2, wherein, the first straight segment has a length in a range from about 0.889 mm to about 1.143 mm.

8. The stationary component of claim 1 or 2, wherein, the second straight segment has a length in a range from about 1.905 mm to about 3.175 mm.

9. The stationary component of claim 1 or 2, wherein, the first straight segment and the second straight segment enclose an angle in a range from about 120 degrees to about 150 degrees.

10. The stationary component of claim 1 or 2, wherein, the tip segment has a length in a range from about 1.143 mm to about 1.397 mm.

11. The stationary component of claim 1 or 2, wherein, The third curved section, when undeformed, orients the tip section to enclose an angle with the second straight section in a range from about 90 degrees to about 120 degrees.

12. The stationary component of claim 1 or 2, wherein, At least one of the first curved section or the second curved section includes a tapered portion having a width less than about 0.762 mm.

13. The stationary component of claim 1 or 2, wherein, At least one of the first straight section, the second straight section, or the tip section includes a tapered portion having a width less than about 0.762 mm.

14. The stationary component of claim 12, wherein, The tapered portion includes a proximal portion having a width of about 0.762 mm, an intermediate portion having a width of about 0.635 mm, and a distal portion having a width of about 0.762 mm.

15. The stationary component of claim 12, wherein, The tapered portion includes a variation in width of the teeth of at least about 0.127 mm; and / or The tapered portion includes a cutout, and wherein the width includes a width of the teeth less a width of a widest portion of the cutout.

16. The stationary component of claim 13, wherein, The tapered portion includes a variation in width of the teeth of at least about 0.127 mm; and / or The tapered portion includes a cutout, and wherein the width includes a width of the teeth less a width of a widest portion of the cutout.

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