Medical device fixation with anti-rotation feature

Abstract

A fixation device includes: a first elongate body configured to extend distally from a distal end of an implantable medical device, the first elongate body including: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature configured to resist rotation of the helix within the tissue, where the anti-rotation feature includes a varying pitch of the helix, the varying pitch results at least in part from an undulating configuration of the one or more coils of the helix.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 369,443, filed on July 26, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to medical devices, and more particularly to the fixation of medical devices. Background Art

[0003] Various types of implantable medical devices (IMDs) have been implanted for treating or monitoring one or more conditions in a patient. Such IMDs may be suitable for monitoring or treating conditions or functions related to the heart, muscles, nerves, brain, stomach, endocrine organs, or other organs and their associated functions. Such IMDs may be associated with leads that position electrodes at desired locations, or may be leadless, with electrodes integrated with and / or attached to the device housing. These IMDs may have the ability to wirelessly transmit data to another device implanted in the patient or another instrument positioned outside the patient's body, or both.

[0004] A pacemaker is an IMD that is constructed to deliver cardiac pacing therapy to restore a more normal heart rhythm. Such an IMD senses the electrical activity of the heart and delivers cardiac pacing via electrodes based on the sensed electrical activity. Some pacemakers are implanted at a distance from the heart and are coupled to one or more leads that extend intravascularly into the heart to position the electrodes relative to the heart tissue. Some pacemakers are sized to be fully implanted in one of the chambers of the heart and may include electrodes that are integrated with or attached to the device housing instead of leads. Some pacemakers provide dual-chamber functionality by sensing and / or stimulating the activity of both the atria and ventricles, or provide other multi-chamber functionality. A pacemaker may provide multi-chamber functionality via leads that extend to the corresponding heart chambers, or multiple pacemakers may provide multi-chamber functionality by being implanted in the corresponding chambers. Summary of the invention

[0005] In general, the present disclosure relates to configurations of fixation devices for implantable medical devices. More specifically, the present disclosure relates to implantable medical devices having fixation devices that include one or more anti-rotation features that resist rotation and / or displacement of the device, for example, due to movement of cardiac tissue to which the device is fixed. In some examples, the fixation device includes a helix that rotates into the tissue, and the anti-rotation feature resists reverse rotation of the helix out of the tissue. In some examples, the fixation devices are embodied as one or more electrodes of the implantable medical device.

[0006] In some examples, a single implantable medical device implanted in one chamber is capable of sensing cardiac pacing and / or delivering cardiac pacing to more than one chamber, which can avoid the need for a leaded device or multiple smaller devices to provide such functionality, which can reduce the amount of material implanted in the patient. In some examples, such an implantable medical device includes a first electrode configured to penetrate the wall tissue of the cardiac chamber in which the device is implanted and enter the wall tissue of another cardiac chamber. In addition to the first electrode, the device also includes a second electrode configured to contact the wall tissue of the chamber in which the device is implanted without penetrating the wall tissue. The electrode can be connected to the distal end of the device. The first electrode can be a spiral including one or more anti-rotation features that prevent the device from rotating. In addition to avoiding device displacement, the anti-rotation feature in such an implantable medical device can prevent or reduce reverse rotation that may cause the first electrode and the second electrode to lose contact with their respective intended cardiac tissues.

[0007] In one example, the present disclosure relates to a fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, wherein at least one of the one or more coils defines an anti-rotation feature configured to resist rotation of the helix within the tissue; and a second slender body configured to extend from the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body.

[0008] In another example, the present disclosure relates to a device comprising: an elongated shell extending from a proximal end of the shell to a distal end of the shell, the elongated shell being configured to be fully implanted in a first chamber of a heart, the first chamber of the heart having wall tissue; a first electrode extending distally from the distal end of the elongated shell, the first electrode comprising: a distal end of the first electrode, the distal end being configured to penetrate from the first chamber into wall tissue of a second chamber of the heart separated from the first chamber; and a first elongated body defining a helix extending to the distal end of the first electrode, the helix having an anti-rotation feature, the anti-rotation feature being Configured to resist rotation of the first electrode within the wall tissue of the second chamber or within the wall tissue of the first chamber; a second electrode, the second electrode extending from the distal end of the slender shell, wherein the second electrode is separated from the first electrode; a second slender body, the second slender body extending distally from the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body; and a signal generating circuit, the signal generating circuit within the slender shell, the signal generating circuit coupled to the first electrode and the second electrode, wherein the signal generating circuit is configured to deliver cardiac pacing to the second chamber via the first electrode and to deliver cardiac pacing to the first chamber via the second electrode.

[0009] In another example, the present disclosure is directed to a method comprising: delivering cardiac pacing from a device to a heart, wherein the device comprises: an elongated shell extending from a proximal end of the shell to a distal end of the shell, the elongated shell being configured to be fully implanted in a first chamber of a heart, the first chamber of the heart having wall tissue; a first electrode extending distally from the distal end of the elongated shell, the first electrode comprising: a distal end of the first electrode, the distal end being configured to penetrate into wall tissue of a second chamber of the heart separated from the first chamber of the heart; and a first elongated body, the A first elongated body defines a helix having an anti-rotation feature configured to resist rotation of the first electrode within the wall tissue of the second chamber; a second electrode extending from the distal end of the elongated shell, wherein the second electrode is separated from the first electrode; and a second elongated body configured to extend from the distal end of the implantable medical device, wherein the second elongated body is separated from the first elongated body, wherein delivering the cardiac pacing includes: delivering the cardiac pacing to the second chamber via the first electrode; and delivering the cardiac pacing to the first chamber via the second electrode.

[0010] In another example, the present disclosure relates to a method comprising: forming a first slender body into one or more coils of a spiral, wherein at least one of the one or more coils defines an anti-rotation feature portion, which is configured to resist rotation of the spiral within the patient's tissue; disposing the spiral on a distal end of an implantable medical device so that the spiral extends distally from the distal end; and disposing a second slender body on the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body, and wherein the second slender body is configured to flexibly maintain contact with the tissue without penetrating the tissue.

[0011] In another example, the present disclosure is directed to a fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, wherein at least one of the one or more coils defines an anti-rotation feature configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises a leaf-shaped geometry, and wherein the helix defines a plurality of leaves configured to form the leaf-shaped geometry.

[0012] In another example, the present disclosure relates to a fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, the helix comprising a distal portion, a middle portion, and a proximal portion; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises the middle portion having a smaller diameter than the distal portion and the proximal portion.

[0013] In another example, the present disclosure relates to a fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, the helix comprising a distal portion, a middle portion, and a proximal portion; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises the middle portion having a smaller pitch than the distal portion and the proximal portion.

[0014] In another example, the present disclosure relates to a fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises a varying pitch of the helix, the varying pitch being produced by an undulating configuration of the one or more coils of the helix.

[0015] This summary is intended to provide an overview of the subject matter described in this disclosure. This summary is not intended to provide an exclusive or exhaustive explanation of the methods and systems described in detail in the following figures and specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The details of one or more examples of the disclosure are set forth in the following drawings and description. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

[0017] Figure 1 is a conceptual diagram illustrating an exemplary device implanted in a patient's heart according to one or more aspects of the present disclosure.

[0018] Figure 2 The present invention is a method for illustrating one or more aspects of the present invention. Figure 1 A perspective view of an exemplary device.

[0019] Figure 3 The present invention is a method for illustrating one or more aspects of the present invention. Figure 1 and Figure 2 A functional block diagram of an exemplary configuration of an IMD.

[0020] Figure 4 It is implanted at the target implantation site Figures 1 to 3 Conceptual image of the device.

[0021] Figure 5A , Figure 5B and Figure 5C According to one or more aspects of the present disclosure Figures 1 to 4 Partial views of a device from different viewing angles.

[0022] Fig. 6A , Figure 6B , Figure 6C and Fig.6D It is shown Figure 5C Conceptual illustration of a top view of a first electrode of an exemplary device.

[0023] Figure 7It is shown Figures 1 to 4 Conceptual illustration of another example anti-rotation feature of an example device of .

[0024] Figure 8 It is shown Figures 1 to 4 Conceptual illustration of another example anti-rotation feature of an example device of .

[0025] Fig. 9A It is shown Figures 1 to 4 Conceptual illustration of different views of another example anti-rotation feature of an example device of.

[0026] Fig. 9B It is shown Fig. 9A Conceptual illustration of a top view of a first electrode of an exemplary device 104 .

[0027] Fig.10 is a flow chart illustrating an exemplary process for deploying an exemplary apparatus.

[0028] Fig.11 is a flow chart illustrating an exemplary process for manufacturing an exemplary anti-rotation feature of an exemplary device.

[0029] Fig.12 is a flow chart illustrating another example process for manufacturing an example anti-rotation feature of an example device. DETAILED DESCRIPTION

[0030] In general, the present disclosure relates to configurations of fixation devices for implantable medical devices. More specifically, the present disclosure relates to implantable medical devices having fixation devices that include one or more anti-rotation features that can resist rotation and / or displacement of the device, for example, due to movement of cardiac tissue to which the device is fixed. The anti-rotation features can resist reverse rotation of the fixation device out of the tissue.

[0031] Figure 1 1 is a conceptual diagram illustrating an exemplary device 104 implanted in a patient's heart 102 according to one or more aspects of the present disclosure. The device 104 is shown implanted in a target implantation region 106 in the right atrium (RA) of the patient's heart 102, such as the triangle of Koch in the patient's heart 102, with the distal end of the device 104 pointing toward the left ventricle (LV) of the patient's heart 102. Figure 1 In the example of , the distal end of the device 104 is directed toward the LV, but the distal end may be directed toward other targets, such as the ventricular septum of the heart 102. The target implantation region 106 may be located between the His bundle and the coronary sinus, and may be adjacent to the tricuspid valve.

[0032] The device 104 includes a distal end 110 and a proximal end 116. The distal end 110 includes a first electrode 112 and a second electrode 114. The first electrode 112 extends from the distal end 110 and can penetrate the wall tissue of a first chamber (e.g., the RA in the example shown) into the wall tissue of a second chamber (e.g., the ventricular myocardium 108 of the LV in the example shown). The second electrode 114 extends from the distal end 110 and is configured to flexibly maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

[0033] The first electrode 112 may define a spiral shape, for example, as Figure 1 The first electrode 112 may further define one or more anti-rotation features configured to prevent rotation and displacement of wall tissue of the heart 102. In some examples, the one or more anti-rotation features may include one or more of the shape and / or size of the helical shape of the first electrode 112. In other examples, the one or more anti-rotation features may include additional anti-rotation features (e.g., tines, etc.) disposed on the first electrode 112.

[0034] Figure 1 The configuration of electrodes 112 and 114 shown allows device 104 to sense cardiac signals and / or deliver cardiac pacing to multiple chambers of heart 102, such as the RA and ventricles in the example shown. In this manner, the configuration of electrodes 112 and 114 can facilitate delivery of AV synchronized pacing by a single device 104 implanted in a single chamber (e.g., the RA). Figure 1 In the example shown, the device 104 is implanted at the target implant region 106 to sense and / or pace the RA and ventricles, but the device having an electrode configuration according to examples of the present disclosure may be implanted at any of a variety of locations to sense and / or pace any two or more chambers of the heart 102. For example, the device 104 may be implanted in region 106 or another region, and the first electrode 112 may extend into tissue of the LV or ventricular septum (e.g., myocardial tissue) to, for example, facilitate the delivery of AV synchronized pacing. In addition, the device having an electrode configuration according to examples of the present disclosure may be implanted at any of a variety of locations in the patient's body for sensing and / or delivering therapy to other patient tissues.

[0035] Additionally, the anti-rotation features described herein are primarily described in the context of a cardiac pacemaker that is configured to be implanted in one chamber and deliver pacing and sensing in that chamber and in another chamber. However, the anti-rotation features described herein may be included on any fixation element on any implantable medical device, such as an implantable stimulator or implantable lead that is configured to be fixed at any location or tissue in the body.

[0036] Figure 2 is a perspective view showing the device 104. The device 104 includes a housing 202 that defines a hermetically sealed internal cavity. The housing 202 can be formed of a conductive material, including titanium or a titanium alloy, stainless steel, MP35N (non-magnetic nickel-cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metal or metal alloy, or other suitable conductive material. In some examples, the housing 202 is formed of a non-conductive material, including ceramic, glass, sapphire, silicone, polyurethane, epoxy resin, acetyl copolymer plastic, polyetheretherketone (PEEK), liquid crystal polymer, other biocompatible polymers, or other suitable non-conductive materials.

[0037] The housing 202 extends between a distal end 204 and a proximal end 206. In some examples, the housing can be cylindrical or substantially cylindrical, but can also be other shapes, such as prismatic or other geometric shapes. The housing 202 can include, for example, a delivery tool interface member 208 located at the proximal end 206 for engaging with a delivery tool during implantation of the device 104. At the distal end 204, the housing 202 can define a face of the housing 202. The face of the housing 202 can be orthogonal to the longitudinal axis 212.

[0038] During pacing and / or sensing, all or substantially all or a portion of housing 202 may be used as electrode 210, such as an anode. In some examples, electrode 210 may surround a portion of housing 202 at or near proximal end 206. Electrode 210 may completely or partially surround housing 202. Figure 2 The electrode 210 is shown extending as a single strip. The electrode 210 may also include multiple segments spaced a distance apart along the longitudinal axis 212 of the housing 202 and / or around the perimeter of the housing 202.

[0039] When the housing 202 is formed of a conductive material such as a titanium alloy, portions of the housing 202 may be electrically insulated by a coating of a non-conductive material such as parylene, polyurethane, silicone, epoxy, or other biocompatible polymer or other suitable material. For portions of the housing 202 that do not have a non-conductive material, one or more discrete areas of the housing 202 having a conductive material may be exposed to define the electrodes 210.

[0040] When the housing 202 is formed of a non-conductive material (such as a ceramic, glass or polymer material), a conductive coating or layer (such as titanium, platinum, stainless steel, alloys thereof), a conductive material may be applied to one or more discrete areas of the housing 202 to form the electrodes 210.

[0041] In some examples, the electrode 210 can be a component mounted or assembled to the housing 202, such as a ring electrode. When the housing 202 is a non-conductive material, the electrode 210 can be electrically coupled to the internal circuit of the device 104 via the conductive housing 202 or the electrical conductor. In some examples, the electrode 210 is located near the proximal end 206 of the housing 202 and can be referred to as a proximal housing-based electrode. The electrode 210 can also be located at other locations along the housing 202, such as near the distal end 204 or at other locations along the longitudinal axis 212.

[0042] Each of the first electrode 112 and the second electrode 114 extends from a first end fixedly attached to the housing 202 at or near the distal end 204 to a second end. Figure 2 In some examples, the second end is not attached to the housing 202 other than via the first end (e.g., is a free end). The first electrode 112 includes one or more coatings configured to define a first electroactive region 216, and the second electrode 114 includes one or more coatings configured to define a second electroactive region 218. In some examples, the first electroactive region 216 can be closer to the second end of the first electrode 112, such as the distal end, and the second electroactive region 218 can be closer to either end of the second electrode 114. Figure 2 In the example of FIG. 1 , the first electroactive region 216 includes the distal end of the electrode 112 .

[0043] The first electrode 112 and the second electrode 114 can be formed of a conductive material such as titanium, platinum, iridium, tantalum, or alloys thereof. The first electrode 112 and the second electrode 114 can be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy, or other insulating coating, to reduce the conductive active surface area of ​​the first electrode 112 and the second electrode 114, thereby defining the first electroactive region 216 and the second electroactive region 218. Defining the first electroactive region 216 and the second electroactive region 218 by covering the portion with an insulating coating can increase the electrical impedance of the first electrode 112 and the second electrode 114, and thereby reduce the current delivered during the pacing pulse that captures the cardiac tissue. The lower current consumption saves the power source of the device 104, such as one or more rechargeable or non-rechargeable batteries.

[0044] In some examples, first electrode 112 and second electrode 114 may have a conductive material coating on first electrically active region 216 and second electrically active region 218 to define active regions. For example, first electrically active region 216 and second electrically active region 218 may be coated with titanium nitride (TiN). First electrode 216 and second electrode 218 may be made of substantially similar materials, or may be made of different materials from each other.

[0045] exist Figure 2 In some examples, the first electrode 112 is in the form of a spiral. In some examples, a spiral is an object having a three-dimensional shape that resembles a wire uniformly wound in a single layer around a cylindrical or conical surface, such that if the surface were unfolded into a plane, the wire would be a straight line. The second electrode 114 includes a ramp portion that can be configured as a partial spiral, such as a spiral that does not make a full rotation around the circumference of a cylindrical or conical surface.

[0046] The first electrode 112 may define one or more anti-rotation features along the length of the first electrode 112. The one or more anti-rotation features may prevent rotation of the first electrode 112 within the tissue of the heart 102, for example, by increasing friction between the first electrode 112 and the tissue. The one or more anti-rotation features (e.g., friction or other securing forces provided by the features) may be sufficient to resist rotation of the first electrode 112 due to movement of the tissue of the heart 102, but may not be sufficient to resist rotation of the first electrode 112 by a clinician, for example, to remove the device 104 from the heart 102. The one or more anti-rotation features may resist forces up to about 5 ounce-force inches (ozf.in) (e.g., about 0.03531 Newton meters (Nm)). The amount of force exerted by the tissue on the first electrode 112 may vary based on the movement of the heart 102, the movement of the device 104, the movement of fluids within the heart 104, the size of the heart 102, etc.

[0047] The one or more anti-rotation features may include a shape of the first electrode 112, a size of the first electrode 112 (e.g., outer diameter, pitch, etc.), and / or one or more other characteristics of the first electrode 112. In some examples, the one or more anti-rotation features include a geometric shape of the first electrode 112, a multi-diameter configuration of the first electrode 112, a multi-pitch configuration of the first electrode 112, a waveform configuration of the first electrode 112, or any combination thereof.

[0048] In some examples, the first electrode 112 may include one or more anti-rotation features disposed on an outer surface of the first electrode 112. The one or more anti-rotation features disposed on the first electrode 112 may include, but are not limited to, an elongated dart, a barb, or a tine. The one or more anti-rotation features may resist rotation of the first electrode 112 (e.g., by penetrating tissue, by increasing friction between the first electrode 112 and the tissue, etc.).

[0049] like Figure 2As shown, the first electrode 112 can be a right-handed spiral and the second electrode 114 can be a left-handed partial spiral, but in other examples, the handedness of the electrodes can be switched or the electrodes can have the same handedness as each other. For example, the spiral of the first electrode 112 can be wound in the same direction as the partial spiral of the second electrode 114. Figure 2 In some examples, the spirals and partial spirals defined by the first electrode 112 and the second electrode 118, respectively, have the same pitch, although in other examples they may have different pitches. In some examples, the first electrode 112 has a varying pitch along the longitudinal axis 212. In some examples, one or both of the electrodes 112 and 114 may have a shape other than a spiral. For example, the first electrode 112 may have a geometric shape (e.g., a triangular shape, a rectangular shape, a hexagonal shape, an octagonal shape, a leaf shape, etc.). The varying shape and / or pitch may cause the first electrode 112 to resist rotation within the tissue of the heart 102.

[0050] The size and shape of first electrode 112 and second electrode 114 may also vary in order to enhance tissue contact of first electroactive region 216 and second electroactive region 218. For example, first electrode 112 and second electrode 114 may have a circular cross-section, or may be made with a flatter cross-section (e.g., oval or rectangular) based on tissue contact specifications. The size and shape of first electrode 112 and second electrode 114 may also be determined by stiffness requirements. For example, stiffness requirements may vary based on expected implantation requirements, including the tissue in which the electrodes are implanted or contacted, and how long the device 104 is intended to be implanted.

[0051] The distal end of the first electrode 112 may have a conical, hemispherical, or beveled edge distal tip having a narrow tip diameter, such as less than 1 millimeter (mm), for penetrating into and through tissue layers. In some examples, the distal end of the first electrode may be a sharp or angled tip or a sharp or beveled edge, but the sharpness may be constrained to avoid a cutting action that may cause lateral displacement of the distal end of the first electrode 112 and undesired tissue trauma. In some examples, the helix of the first electrode 112 may have a maximum diameter at its base where it intersects with the housing distal end 204. In such examples, the diameter of the first electrode 112 may decrease from the housing distal end 204 to the distal end of the first electrode 112. In some examples, the diameter of the first electrode 112 may vary from the housing distal end 204 to the distal end of the first electrode 112. The varying diameter may cause the first electrode 112 to resist rotation within the tissue of the heart 102.

[0052] The outer dimensions of the first electrode 112 can be substantially straight and cylindrical, and in some examples the first electrode 112 is rigid. In some examples, the first electrode 112 and the second electrode 114 can be flexible in the lateral direction, being non-rigid to allow some flexure with cardiac motion. In a relaxed state, when not subjected to any external forces, the first electrode 112 and the second electrode 114 can be configured to maintain a distance between the first electroactive region 216 and the second electroactive region 218 and the housing distal end 204.

[0053] The distal end of the first electrode 112 can penetrate one or more tissue layers to position the first electroactive region 216 within a desired tissue layer, such as the ventricular myocardium 108 or the interventricular septum. Thus, the first electrode 112 extends from the housing distal end 204 a distance corresponding to the depth of the intended pacing site and can have a relatively high compressive strength along its longitudinal axis, which can be substantially similar to the longitudinal axis 212 to resist bending in a lateral or radial direction when a longitudinal force, an axial force, and / or a rotational force is applied to, for example, the proximal end 206 of the housing 202 to advance the device 104 into tissue at the target implantation area 106. When the first electrode 112 is a helical electrode, the first electrode 112 can maintain a spacing between the plurality of windings of the first electrode 112 by resisting bending in a lateral or radial direction. The spacing can be a predetermined pitch of the first electrode 112 and can vary from the distal end 204 to the distal end of the first electrode 112. The first electrode 112 can be longitudinally non-compressible. However, when subjected to lateral or radial forces, the first electrode 112 may also be elastically deformable in the lateral or radial directions to allow, for example, temporary flexing as tissue moves, but when the lateral force is reduced, the first electrode returns to its normal straight position. In some examples, when the first electrode 112 is not exposed to any external force or is only exposed to a force along its longitudinal axis (substantially similar to the longitudinal axis 212), the first electrode 112 maintains a straight linear position as shown.

[0054] In some examples, the second electrode 114 or the electrode 210 can be paired with the first electrode 112 for sensing ventricular signals and delivering ventricular pacing pulses. In some examples, the second electrode 114 can be paired with the electrode 210 or the first electrode 112 for sensing atrial signals and delivering pacing pulses to atrial tissue (e.g., atrial myocardium) in the target implant area 106. In other words, in some examples, the electrode 210 can be paired with the first electrode 112 and the second electrode 114 at different times for ventricular functionality or atrial functionality, respectively. In some examples, the first electrode 112 and the second electrode 114 can be paired with each other at different polarities for atrial functionality and ventricular functionality.

[0055] In some examples, the second electrode 114 can be configured as an atrial cathode electrode for delivering pacing pulses to atrial tissue at the target implant area 106 in combination with the electrode 210. The second electrode 114 and the electrode 210 can also be used to sense an atrial P wave for controlling an atrial pacing pulse (delivered in the absence of a sensed P wave), and for controlling an atrial synchronized ventricular pacing pulse delivered using the first electrode 112 as a cathode and the electrode 210 as a return anode.

[0056] At the distal end 204, the device 104 includes a distal fixation assembly 214, which includes a first electrode 112, a second electrode 114, and a housing distal end 204. The distal end of the first electrode 112 can be configured to rest within the patient's ventricular myocardium, and the second electrode 114 can be configured to contact the patient's atrial endocardium. In some examples, the distal fixation assembly 214 may include more or fewer electrodes than two electrodes. In some examples, the distal fixation assembly 214 may include one or more second electrodes along the housing distal end 204. For example, the distal fixation assembly 214 may include three electrodes configured for atrial functionality, such as the second electrode 114, and the three electrodes may be substantially similar or different from each other. The spacing between the plurality of second electrodes 114 may be equal or unequal distances. The second electrode 114 may be individually selectively coupled to the sensing circuit and / or pacing circuit enclosed by the housing 202 to serve as an anode with the first electrode 112 or as an atrial cathode electrode, or may be electrically common and not individually selectable.

[0057] The second electrode 114 is configured to flexibly maintain contact with wall tissue (e.g., the RA endocardium) of the cardiac chamber in which the device 104 is implanted, regardless of changes in the tissue surface or in the distance between the distal end 204 of the shell 202 and the tissue surface, which may occur as the wall tissue moves during the cardiac cycle.

[0058] To flexibly maintain contact with the wall tissue, the second electrode 114 can be flexible and configured to have spring-like properties. For example, the second electrode 114 can be configured to elastically deform, for example, toward the distal end 204 of the housing 202, but can be spring-biased toward a static configuration, and when elastically deformed, the spring bias can push the second electrode away from the distal end 204 of the housing 202. In this way, the elastic deformation and the spring bias can maintain consistent contact of the second electrode with the wall tissue of the chamber in which the device is implanted.

[0059] As described herein, flexibly maintaining contact generally refers to the ability of the electrode to move relative to the housing 202. For example, the electrode can be configured to be elastically deformed as described above. In some examples, the electrode can be additionally attached to the housing 202 by a mechanism such as a spring or a joint, or can include a mechanism such as a spring or a joint that allows movement of the electrode relative to the housing 202. In such examples, the electrode itself does not need to be deformable.

[0060] Figure 3 1 is a functional block diagram showing an exemplary configuration of the device 104. Figure 3 As shown, the device 104 includes electrodes 112 and 114, which can be as shown relative to Figure 1 and Figure 2 For example, as with respect to Figure 1 and Figure 2 As described, the first electrode 112 can be configured to extend from the distal end 204 of the housing 202 and can penetrate the wall tissue of the first chamber (e.g., RA) into the wall tissue of the second chamber (e.g., LV). The second electrode 114 extends from the distal end 204 of the housing 202 and is configured to flexibly maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

[0061] exist Figure 3 In the example shown, the device 104 includes a switching circuit 302, a sensing circuit 304, a signal generating circuit 306, a sensor 308, a processing circuit 310, a telemetry circuit 312, a memory 314, and a power supply 316. The various circuits may be or include programmable or fixed function circuits that are configured to perform the functions attributed to the respective circuits. The memory 314 may store computer readable instructions that, when executed by the processing circuit 310, cause the device 104 to perform various functions. The memory 314 may be a storage device or other non-transitory medium. Figure 3 The components of the device 104 shown in FIG. 1 may be housed within a housing 202 .

[0062] The signal generation circuit 306 generates electrical stimulation signals, such as cardiac pacing pulses. The switching circuit 302 is coupled to the electrodes 112, 114, and 210 and may include one or more switch arrays, one or more multiplexers, one or more switches (e.g., a switch matrix or other set of switches), one or more transistors, or other circuits. The switching circuit 302 is configured to direct the stimulation signal from the signal generation circuit 306 to a selected combination of electrodes 112, 114, and 210 having a selected polarity, for example, to selectively deliver pacing pulses to the RA, ventricle, or interventricular septum of the heart 102. For example, to pace one or both of the ventricles, the switching circuit 302 may couple the first electrode 112 that penetrates through the wall tissue of the ventricle or interventricular septum to the signal generation circuit 306 as a cathode, and couple the second electrode 114 or one or both of the electrodes 210 to the signal generation circuit 306 as an anode. As another example, to pace the RA, the switch circuit 302 may couple the second electrode 114 flexibly held in contact with the RA endocardium to the signal generating circuit 306 as a cathode and couple the first electrode 112 or one or both of the electrodes 210 to the signal generating circuit 306 as an anode.

[0063] The switch circuit 302 may also selectively couple the sensing circuit 304 to a selected combination of the electrodes 112, 114, and 210, for example, to selectively sense electrical activity of the RA or ventricles of the heart 102. The sensing circuit 304 may include a filter, an amplifier, an analog-to-digital converter, or other circuitry configured to sense cardiac electrical signals via the electrodes 112, 114, and / or 210. For example, the switch circuit 302 may couple each of the first electrode 112 and the second electrode 114 (in combination with the electrode 210) to a respective sensing channel provided by the sensing circuit 304 to sense ventricular cardiac electrical signals or atrial cardiac electrical signals, respectively. In some examples, the sensing circuit 304 is configured to detect an event within the cardiac electrical signal, such as a depolarization, and provide an indication of the event to the processing circuit 310. In this manner, the processing circuit 310 may determine the timing of atrial depolarization and ventricular depolarization, and control the delivery of cardiac pacing (e.g., AV synchronized cardiac pacing) based on the timing. The processing circuit 310 may include any one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), discrete logic circuits, or any other processing circuit configured to provide the functionality attributed to the processing circuit 310, which may be embodied herein as firmware, hardware, software, or any combination thereof.

[0064] Sensor 308 may include one or more sensing elements that convert patient physiological activity into electrical signals to sense the value of a corresponding patient parameter. Sensor 308 may include one or more accelerometers, optical sensors, chemical sensors, temperature sensors, pressure sensors, or any other type of sensor. Sensor 308 may output a patient parameter value that may be used as feedback to control the sensing and delivery of therapy by device 104.

[0065] Telemetry circuit 312 supports communication between device 104 and an external programmer ( Figure 3 The processing circuit 310 of the device 104 may receive updates on the operating parameters from the computing device and provide the collected data, such as sensed cardiac activity or other patient parameters, via the telemetry circuit 312. The telemetry circuit 312 may enable communication via radio frequency (RF) communication techniques, such as via an antenna (not shown).

[0066] The power supply 316 delivers operating power to the various components of the device 104. The power supply 316 may include a rechargeable or non-rechargeable battery and a power generation circuit to generate operating power. Recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within the device 104.

[0067] Figure 4 1 is a conceptual diagram of a device 104 implanted at a target implantation region 106. The first electrode 112 can be inserted so that the tissue engages with the helix of the first electrode 112. When the first electrode 112 engages with the tissue, the first electrode 112 penetrates into the tissue at the target implantation region 106 and advances through the atrial myocardium 406 and the central fiber body 402 to position the first electrically active region 216 in the ventricular myocardium 108, as shown in FIG. Figure 4 In some examples, the first electrode 112 penetrates into the interventricular septum. In some examples, the first electrode 112 does not completely penetrate the ventricular endocardial surface or the epicardial surface.

[0068] In some examples, manual pressure applied to the proximal end 206 of the housing, such as via an advancement tool, provides a longitudinal force to pierce cardiac tissue at the target implantation region 106. In some examples, actuation of the advancement tool causes the device 104 and the first electrode 112 configured as a helix to rotate about the longitudinal axis 212. The rotation of the helix about the longitudinal axis 212 causes the first electrode 112 to be advanced through the atrial myocardium 406 and the central fiber body 402 to position the first electrically active region 216 in the ventricular myocardium 108, such as Figure 4 shown.

[0069] The first electrode 112 may define one or more anti-rotation features, for example, as described with respect to Fig. 6A 9 is shown and described in more detail. One or more anti-rotation features can prevent rotation of the first electrode 112 within cardiac tissue at the target implantation area 106. The one or more anti-rotation features can increase friction between the first electrode 112 and the cardiac tissue at the target implantation area 106 by a predetermined amount. The predetermined increase in friction can prevent the first electrode 112 from rotating due to movement of the cardiac tissue, but may not prevent the first electrode 112 from rotating due to manual pressure applied to the proximal end 206 of the housing (e.g., via an advancement tool).

[0070] As the first electrode 112 is advanced into the tissue, the distance between the second electrode 114 and the atrial endocardium 404 decreases until the second electrode 114 contacts the surface of the atrial endocardium 404 and may be pressed against the surface of the atrial endocardium such that the cardiac tissue engages the second electroactive region 218. The second electrode 114 is maintained in contact with the atrial endocardium 404 by the first electrode 112, e.g., the first electrode 112 prevents the second electrode 114 from retracting from the surface of the atrial endocardium 404. As described herein, the second electrode 114 is also configured to flexibly maintain contact with the atrial endocardium 404. In some examples, the second electrode 114 may be elastically deformable toward the distal end 204 of the housing 202 and have a spring bias that pushes the second electrode 114 distally from the distal end 204. In some examples, the first electrode 112 may be the only anti-rotation feature of the device 104. The distance that the first electrode 112 extends from the housing 202 can be selected so that the first electrically active area 216 reaches an appropriate depth in the tissue layers to reach the target pacing and sensing site, in this case in the ventricular myocardium 108, without penetrating all the way into the adjacent heart chamber.

[0071] In some pacing applications, the target implant region 106 is along the atrial endocardium 404, substantially below the AV node and the bundle of His. The first electrode 112 can have a length that penetrates the atrial endocardium 404 in the target implant region 106, passes through the central fiber body 402 and enters the ventricular myocardium 108 without penetrating the ventricular endocardial surface. In some examples, when the full length of the first electrode 112 is fully advanced into the target implant region 106, the first electrically active region 216 rests within the ventricular myocardium 108, and the second electrode 114 is positioned in close contact with the atrial endocardium 404. In various examples, the first electrode 112 can extend from the housing distal end 204 by about 3 mm to 12 mm. In some examples, the first electrode 112 can extend from the housing 202 by a distance of at least 3 millimeters (mm), in various examples a distance of at least 3 mm but less than 20 mm, less than 15 mm, less than 10 mm, or less than 8 mm. The diameter of the first electrode 112 and the second electrode 114 may be less than 2 mm and may be 1 mm or less, or even 0.6 mm or less.

[0072] Inflammation of the patient's tissue may result from interaction with the device 104. For example, penetration of the tissue by the first electrode and / or contact between the tissue and the second electrode may result in inflammation of the tissue. Inflammation of the patient's tissue near the electrode may result in a higher threshold for stimulation delivered to the tissue to activate or capture the tissue. A higher capture threshold may, in turn, increase consumption of the IMD's power supply associated with the delivery of the stimulation.

[0073] In some examples, an IMD as described herein (such as IMD 104) may include one or more steroid eluting elements (e.g., disposed on a face of distal end 204). Steroids may reduce inflammation of patient tissue resulting from interaction with the IMD. The steroid eluting element may be configured to elute one or more steroids into tissue near the element over time. In some examples, the one or more steroid eluting elements include one or more monolithic controlled release devices (MCRDs).

[0074] In some examples, the IMD includes one or both of a first steroid eluting element and a second steroid eluting element, the first steroid eluting element being configured to elute one or more steroids into tissue near the first electrode, and the second steroid eluting element being configured to elute one or more steroids into tissue near the second electrode. The IMD 104 includes a steroid eluting element at the distal end 204 of the housing 202, for example, included in the head 502, attached to the head, or formed on the head. The steroid eluting element can elute one or more steroids into wall tissue near the second electrode 114.

[0075] Figure 5A , Figure 5B and Figure 5CAccording to one or more aspects of the present disclosure Figures 1 to 4 Partial views of a device from different viewing angles. Figure 5A 2 is a partial view of the distal end 110 of the device 104 including the distal fixation assembly 214. The housing 202 includes a head 502. In some examples, the head 502 can be separate from or integral with the housing 202 and can be made of the same or different material as the housing 202. The housing distal end 204 (e.g., the head 502 or the face 503 of the distal end 204) defines a recess 504 (e.g., a recessed channel) to receive at least a portion of the second electrode 114 when the second electrode 114 is elastically deformed toward the housing 202. When the second electrode 114 is partially or completely deformed into the recess 504, the second electroactive region 218 can maintain contact with the tissue surface.

[0076] In some examples, the second electrode 114 can maintain contact with tissue as the degree of deformation of the second electrode 114 toward the housing 202 varies. The second electrode 114 can be spring biased to an undeformed position, and deformation of the second electrode 114 proximally toward the distal end 204 of the housing 202 can result in a spring force directed distally from the housing 202 that pushes the second electrode 114 and more specifically the second electroactive region 218 against cardiac tissue. For example, the deformation of the second electrode 114 can vary with the movement of the heart. Due at least in part to the change in the ability of the second electrode 114 to deform, for example, during the cardiac cycle, the second electroactive region 218 can maintain consistent contact with tissue and provide pacing to the heart.

[0077] The second electrode 114 can extend from the first end 508 to the second end 510. The first end 508 can be connected to the distal end 204 of the housing 202. In some examples, such as Figure 5A As shown, the second electrode 114 may extend distally from the first end 508 toward the second electroactive region 218. The second end 510 may be connected to the distal end 204 or may be a free end (eg, free floating).

[0078] Figure 5B is a conceptual diagram of a partial view of device 104 showing recessed aperture 506 in cut-away form, according to one or more aspects of the present disclosure. Figure 5C 1 is a conceptual diagram of a partial side perspective view of the device 104 according to one or more aspects of the present disclosure. Figure 5B506. As shown, a first end 508 of the second electrode 114 is attached to the head 502 and connected (e.g., electrically connected) to the feedthrough. At the opposite end of the second electrode 114, a second end 510 of the second electrode 114 is bent back toward the device 104 and can move into the recess 506 when the second electrode 114 is deformed. For example, when the second end 510 is pushed into the recess 506 due to the deformation of the second electrode 114 with the movement of the heart, the second electroactive region 218 can remain in contact with the tissue.

[0079] As discussed herein, the first electrode 112 and the second electrode 114 can have different hand-screw shapes. For example, the spiral of the first electrode 112 can be a right-hand spiral. The first electrode 112 can be inserted, for example, in a manner similar to rotating and advancing a threaded screw so that the tissue engages with the spiral of the first electrode 112. The partial spiral of the second electrode 114 can be a left-hand or right-hand spiral. When the distance between the second electrode 114 and the tissue is reduced due to the right-hand rotation of the first electrode 112, the tissue will gradually contact the sloped portion 512 of the second electrode 114 similar to advancing along a ramp (in Figure 5C ), and the slope shape of the slope portion 512 will gradually deform toward the housing 202, such as compression.

[0080] In some examples, the first electrode 112 includes a spiral having a first pitch, and the ramp portion 512 of the second electrode 114 is a partial spiral having a second pitch. The first pitch of the spiral of the first electrode 112 can be the same, substantially similar, or different than the second pitch of the partial spiral of the second electrode 114. In some examples, the second electrode 114 can be more peripheral than the first electrode 112 relative to the longitudinal axis 212. In some examples, the first electrode 112 is located in the interior space defined by the second electrode 114 and is substantially concentric with the second electrode 114.

[0081] FIG. 6A to FIG. 6D are shown separately Figure 5C Conceptual diagram of an exemplary top view of the first electrode 112 of the device 104. FIG. 6A to FIG. 6D Anti-rotation features including shapes 602A-602D (collectively “shapes 602”) are shown. FIG. 6A to FIG. 6D Shapes 602A to 602D are shown as a hexagonal shape, a rectangular shape, an octagonal shape, and a leaf shape, respectively. In other examples, shape 602 may include one or more other geometric shapes (e.g., a triangle, a heptagon, an ellipse, etc.). Each of shapes 602 may be defined by a plurality of edges 603 connected at a plurality of vertices 601.

[0082] The shape 602 can resist rotation of the first electrode 112 in cardiac tissue. Due to one or more edges of the shape 602, the shape 602 can resist movement of the first electrode 112 within the tunnel created by the first electrode 112 during implantation. The edges of the shape 602 can contact tissue around the tunnel created by the first electrode 112 and increase resistance to movement of the first electrode 112. The shape 602 can be centered about the longitudinal axis 212 and can have a width and / or diameter D1. The clinician can determine the value of D1 based at least in part on the expected forces acting on the first electrode 112 and the range of user-selected forces that the first electrode 112 will resist.

[0083] like Fig.6D As shown, the leaf shape 602D can be defined by a plurality of protrusions 604 (also referred to as "lobes 604"). Each of the protrusions 604 can extend radially outward at the center and radially inward at the edges. Each of the protrusions 604 can include an outwardly directed vertex 606 located between adjacent inwardly directed vertices 608. Each of the protrusions 604 can connect adjacent protrusions 604 at the edges. In some examples, the edges of the shape 602 can be tortuous. In some examples, the edges of the shape 602 and / or the outwardly directed vertices 606 can be sharp, for example to facilitate the first electrode 112 to penetrate the heart tissue.

[0084] In some examples, one or more coils of the first electrode 112 may be out of radial phase with adjacent coils of the first electrode 112. For example, where the shape 602 is a rectangular shape 602B, the vertices 601 of the first coil defining the rectangular shape 602B may be spaced up to 90 degrees from corresponding vertices 601 of one or more of the adjacent coils.

[0085] Figure 7 It is shown Figures 1 to 4 104. The anti-rotation feature 702 includes a multi-diameter configuration of the first electrode 112. The first electrode 112 extends distally from the distal end 204 of the housing 202 along the longitudinal axis 212 and includes a plurality of portions. Figure 7 A first electrode 112 is shown, the first electrode including a first portion 704 having an outer diameter D2, a second portion 706 having an outer diameter D3, and a third portion 708 having an outer diameter D4. In other examples, the first electrode 112 may include two portions or four or more portions. Each portion of the plurality of portions may correspond to one or more coils (e.g., one or more complete coils) of the helix of the first electrode 112. Each portion of the plurality of portions may have an outer diameter different from at least another portion of the plurality of portions.

[0086] like Figure 7 As shown, the first portion 704 can be connected to the distal end 204 of the housing 202 (e.g., connected to the face 503 of the housing 202). The first portion 704 can extend distally from the distal end 204 along the longitudinal axis 212. The second portion 706 can be connected to the first portion 704 and can extend distally from the first portion 704. The third portion 708 can be connected to the second portion 706 and can extend distally from the second portion 706. The first electroactive region 216 can be disposed on the third portion 708.

[0087] In some examples, outer diameters D2 and D4 can be larger than outer diameter D3, thereby forming an hourglass configuration of first electrode 112. In the hourglass configuration, first electrode 112 can compress cardiac tissue between the coils of the first electrode and can resist movement of first electrode 112 along a tunnel within cardiac tissue in an area defined by a portion having a smaller outer diameter (e.g., an area defined by second portion 706) (e.g., movement of third portion 708). In some examples, outer diameters D3 and D4 can be larger than outer diameter D2, or outer diameters D2 and D3 can be larger than outer diameter D4.

[0088] In the hourglass configuration, outer diameters D2 and D4 may have the same outer diameter value that is greater than outer diameter D3. In some examples, outer diameters D2 and D4 may have different outer diameter values ​​that are greater than outer diameter D3. The outer diameter values ​​of D2, D3, and D4 may be user-selected to resist rotation of device 104 in a determined range of forces acting on device 104.

[0089] Figure 8 It is shown Figures 1 to 4 1. Conceptual diagram of another exemplary anti-rotation feature 802 of the exemplary device 104 of FIG. The anti-rotation feature 802 may be a multi-pitch configuration of the first electrode 112. Figure 8 As shown, the spiral of the first electrode 112 may include multiple parts, each of the multiple parts including one or more coils of the spiral. Figure 8 As shown, the first electrode 112 may include a first portion 804, a second portion 806, a third portion 808, and a fourth portion 810 arranged along the first electrode 112 from the distal end 204 to the distal end of the first electrode 112. In other examples, the plurality of portions may include two portions, three portions, or four or more portions. At least one portion of the plurality of portions may have a different pitch than another portion of the plurality of portions.

[0090] like Figure 8As shown, the first portion 804 and the fourth portion 810 defining the proximal end and the distal end of the first electrode 112 have a larger pitch than the second portion 806 and the third portion 808. In other examples, the second portion 806 and the third portion 808 may have a larger pitch than the first portion 804 and the fourth portion 810. In some examples, the pitch of the first electrode 112 may increase and / or decrease from the distal end 204 to the distal end of the first electrode 112.

[0091] The portion of the first electrode 112 having a different pitch can interfere with the proximal movement of a portion of the first electrode 112 within the tunnel and can prevent rotation of the device 104. When the fourth portion 810 is retracted from the heart tissue, the fourth portion 810 engages with the portion of the tunnel corresponding to the third portion 808 and encounters increased resistance due to the change in pitch. A similar effect can occur when the second portion 804 is retracted proximally and engages with the portion of the tunnel corresponding to the first portion 802.

[0092] like Figure 7 and Figure 8 As shown, the second electrode 114 can define a partial spiral 710. The partial spiral 710 can be wound in the same direction as the first electrode 112.

[0093] Fig. 9A and Fig. 9B It is shown Figures 1 to 4 104. Conceptual illustration of different views of another example anti-rotation feature 902 of the example device 104. Fig. 9A A side view of the distal portion 110 of the device 104 is shown. Fig. 9B Shows Fig. 9A A top view of the first electrode 112 of the device 104.

[0094] The anti-rotation feature 902 includes a wavy configuration of the helix of the first electrode 112. In the wavy configuration, each coil of the helix of the first electrode 112 may include undulations that produce a varying pitch between adjacent coils. The undulations may produce one or more peaks 904 and one or more troughs 906 on each coil. The peaks 904 of the first coil may be separated by a first distance 908 from the troughs 906 of the coils longitudinally adjacent and distal to the first coil. In some examples, the undulations may be sinusoidal.

[0095] The peaks 904 of the first coil may be separated from the troughs 906 of the coils longitudinally adjacent and proximate to the first coil by a second distance 908. The first distance 908 may be less than the second distance 910 and may represent a region of reduced pitch resulting from the alignment of the peaks 904 and the troughs 906. The second distance 910 may represent a region of increased pitch resulting from the alignment of the peaks 904 and the troughs 906. In some examples, the first value 908 and / or the second distance 910 may have the same value for all regions of reduced pitch and all regions of increased pitch on the first electrode 112, respectively. In some examples, one or more regions of reduced pitch and / or one or more regions of increased pitch may have different distance values ​​from one or more other regions of reduced pitch and / or one or more other regions of increased pitch, respectively.

[0096] The location where the pitch decreases (e.g., having the first distance 908) may be located spirally between two regions where the pitch increases (e.g., having the second distance 910). In some examples, the location where the pitch decreases may be a location with a local minimum pitch (e.g., the pitch of one or more coils of the first electrode 112 or the pitch of all coils of the first electrode 112). The location with the local minimum pitch may be located spirally between two regions with a local maximum pitch (e.g., the pitch of one or more coils of the first electrode 122 or the pitch of all coils of the first electrode 112).

[0097] like Fig. 9B As shown in , a top view of the spiral shape in the wavy configuration (eg, at a plane parallel to the face 503 of the distal end 204 ) may show an annular shape without any protrusions toward and / or away from the longitudinal axis 212 .

[0098] The anti-rotation feature 902 can increase the compression of the cardiac tissue between the successive coils of the spiral, thereby increasing the resistance to rotation of the device 104. In some examples, portions of the coil of the anti-rotation feature 902 can protrude toward each other along the longitudinal axis 212 and create a pinch point. The pinch point can increase the compression of the cardiac tissue at the pinch point and increase the resistance of the device 104 to rotation at the pinch point. A user (e.g., a clinician, a manufacturer, etc.) can select the amount of the protrusion to adjust the amount of compression of the cardiac tissue and / or the resistance of the anti-rotation feature 902. The shape of the waveform of the anti-rotation feature 902 can be user-selected and can depend at least in part on the size of the device 104, the size of the first electrode 112, and / or the anatomical structure of the heart 102.

[0099] In some examples, the first electrode 112 can individually define each of the above anti-rotation features (e.g., shape 602, anti-rotation feature 702, anti-rotation feature 802, anti-rotation feature 902). In other examples, the first electrode 112 can define any combination of two or more of the anti-rotation features. For example, the first electrode 112 can combine multiple diameters, multiple pitches, spiral shapes, and / or wave configurations in any combination.

[0100] Fig.10 104 ( Figure 1 ) to describe Fig.10 Although one of ordinary skill in the art will appreciate that the technology may be performed with reference to another implantable medical lead or other medical device.

[0101] The clinician may insert the device 104 into a single first chamber of the heart 102 (1002). The clinician may advance the first electrode 112 extending distally from the housing 202 of the device 104 through the wall tissue of the first chamber and into the wall tissue of a second chamber of the heart 102 (1004). In some examples, the first electrode 112 may form a tunnel within the wall tissue of the heart 102 as the first electrode 112 is advanced through the wall tissue. In some examples, advancing the first electrode 112 includes positioning a distal end (e.g., the first electrically active region 216) of the first electrode 112 within the patient's ventricular myocardium 108.

[0102] The clinician can cause the device 104 to flexibly maintain contact between the second electrode 114 and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber (1006). In some examples, flexibly maintaining contact with the wall tissue of the first chamber with the second electrode 114 includes contacting the atrial endocardium 402 of the patient. In some examples, flexibly maintaining contact with the wall tissue of the first chamber with the second electrode 114 includes deforming the second electrode 114 toward the elongated housing 202 through the wall tissue of the first chamber as the distance between the distal end of the elongated housing 202 and the wall tissue of the first chamber decreases. In some examples, the recess 504 receives at least a portion of the second electrode when the second electrode 114 elastically deforms back toward the elongated housing 202. In some examples, the spring bias of the second electrode 114 pushes the second electrode 114 away from the housing and into consistent contact with the wall tissue of the first chamber.

[0103] When the device 104 is implanted within cardiac tissue, one or more anti-rotation features defined by the first electrode 112 (e.g., by the helix of the first electrode 112) resist rotation of the device 104 due to cardiac tissue movement. The one or more anti-rotation features can prevent movement of the first electrode 112 away from the wall tissue of the second chamber of the heart 102 (e.g., the patient's ventricular myocardium 108). The one or more anti-rotation features can also prevent displacement of the device 104 from within the wall tissue of the first chamber of the heart 102.

[0104] The clinician may deliver cardiac pacing from the device 104 to the second chamber via the first electrode 112 and to the first chamber via the second electrode 114 (1008). The device 104 may deliver cardiac pacing to the first chamber and / or the second chamber via the first electrode 112, the second electrode 114, and / or one or more other electrodes (e.g., electrode 210) of the device 104.

[0105] Fig.11 is a flow chart illustrating an exemplary process for manufacturing an exemplary anti-rotation feature of an exemplary device 104. A manufacturer may form a first electrode 112 (1102). In some examples, the manufacturer may wrap an elongated body including a conductive material around a mandrel (or similar device). The manufacturer may then shape the elongated body into the first electrode 112, for example, into a spiral, a coil having a user-determined shape (e.g., any of the shapes 602 described above), etc.

[0106] The manufacturer can form one or more anti-rotation features (1104) on the first electrode 112. The manufacturer can adjust one or more characteristics of the first electrode 112 (e.g., pitch, outer diameter, vertices 601 of shape 602, etc.) to form the one or more anti-rotation features on the first electrode 112. In some examples, the manufacturer forms the one or more anti-rotation features while forming the first electrode 112. The manufacturer can use a mandrel (e.g., using one or more notches and / or grooves disposed on the mandrel) to form the one or more anti-rotation features.

[0107] In some examples, when a manufacturer wraps the elongated body around a core (e.g., a non-circular core), the material properties of the elongated body can result in increased deformation at the apex 601 compared to the sides 603, thereby generating tension within the elongated body. When a manufacturer removes the elongated body from the core, the tension within the elongated body can result in a change in the shape 602 of the anti-rotation feature and / or a change in the internal angle of the apex 601. When a manufacturer releases the first electrode 112 from the core, adjacent coils of the first electrode 112 can be radially out of phase with each other, for example, due to the tension within the elongated body of the first electrode 112.

[0108] In some examples, the manufacturer can form the shape 602 on the first electrode 112 using a mandrel having a cross-section that has a shape that is different than the intended final shape of the shape 602. For example, the manufacturer can form the rectangular shape 602B on the first electrode 112 using a triangular mandrel, e.g., due to tension within the elongated body of the first electrode 112.

[0109] The manufacturer may then attach the first electrode 112 to the housing 202 of the device 104 (1106). In some examples, the manufacturer may attach the first electrode 112 to the head 502, and then attach the head 502 to the distal end 204 of the housing 202. In some examples, the manufacturer may attach the first electrode 112 to the face 503 of the housing 202. The first electrode 112 may be disposed radially inward of the second electrode 114. The first electrode 112 may be concentric with the second electrode 114.

[0110] Fig.12 1 is a flow chart illustrating another exemplary process for manufacturing an exemplary anti-rotation feature of an exemplary device 104. A manufacturer may form a first electrode 112 using a plurality of winding points (1202). A manufacturer may insert an elongated body including a conductive material into a manufacturing device configured to manufacture the first electrode 112. The manufacturing device may include a plurality of winding points configured to deform and / or deflect the elongated body and shape one or more coils of the first electrode 112 (e.g., one or more coils of a helix of the first electrode 112). The manufacturing device may form the first electrode 112 using point winding, progressive stamping, and other known manufacturing techniques.

[0111] The manufacturer can use the notches in the plurality of winding points to form one or more anti-rotation features (1204) on the first electrode 112. The plurality of winding points can include geometric shapes configured to form at least a portion of the coil of the first electrode 112 into an anti-rotation feature described herein (e.g., shape 602, anti-rotation feature 702, anti-rotation feature 802, anti-rotation feature 902, etc.). In some examples, the manufacturer can use one or more other manufacturing devices, systems, and / or equipment to form the anti-rotation features.

[0112] The manufacturer may then attach the first electrode 112 to the housing 202 of the device 104 (1206). In some examples, the manufacturer may attach the first electrode 112 to the head 502, and then attach the head 502 to the distal end 204 of the housing 202. In some examples, the manufacturer may attach the first electrode 112 to the face 503 of the housing 202. The first electrode 112 may be disposed radially inward of the second electrode 114. The first electrode 112 may be concentric with the second electrode 114.

[0113] It should be understood that the various aspects disclosed herein may be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, depending on the example, certain actions or events of any of the processes or methods described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described actions or events may be required to perform these techniques). In addition, although for clarity, certain aspects of the present disclosure are described as being performed by a single module or unit, it should be understood that the techniques of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0114] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a non-transitory computer-readable medium corresponding to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0115] In addition, it should be noted that the systems described herein may not be limited to the treatment of human patients. In alternative examples, the systems may be implemented in non-human patients, such as primates, canines, equines, pigs, and felines. These other animals may undergo clinical or research treatments that may benefit from the subject matter of the present disclosure.

[0116] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the term "processor" as used herein may refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Additionally, these techniques may be fully implemented in one or more circuits or logic elements.

[0117] Embodiment 1: A fixation device, comprising: a first slender body, which is configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end, which is configured to penetrate into the patient's tissue; and a helix, which has one or more coils, wherein at least one of the one or more coils defines an anti-rotation feature, which is configured to resist rotation of the helix within the tissue; and a second slender body, which is configured to extend from the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body.

[0118] Embodiment 2: The device according to embodiment 1, wherein the first elongated body comprises a first electrode.

[0119] Embodiment 3: The device according to any one of embodiments 1 to 2, wherein the second elongated body comprises a second electrode.

[0120] Embodiment 4: The device of any one of embodiments 1 to 3, wherein the second elongated body is configured to flexibly maintain contact with the tissue without penetrating the tissue.

[0121] Embodiment 5: The device according to any one of embodiments 1 to 4, wherein the second elongated body is configured as a partial helix.

[0122] Embodiment 6: A device according to embodiment 5, wherein the partial helix is ​​wound in the same direction as the helix.

[0123] Embodiment 7: The device of any one of Embodiments 1 to 6, wherein the anti-rotation feature comprises a shape of the helix relative to a plane orthogonal to a longitudinal axis of the implantable medical device.

[0124] Embodiment 8: A device according to embodiment 7, wherein the shape is equilateral.

[0125] Embodiment 9: The device of any one of Embodiments 7 and 8, wherein the shape comprises a plurality of edges connected at a plurality of vertices.

[0126] Example 10: The device of Example 9, wherein the plurality of vertices are configured to improve penetration of the tissue by the distal end of the first elongated body.

[0127] Embodiment 11: The device of any one of Embodiments 7 to 10, wherein the shape comprises a geometric shape, and wherein the spiral defines the geometric shape.

[0128] Embodiment 12: The device of embodiment 11, wherein the spiral is configured as a hexagonal spiral.

[0129] Embodiment 13: The device of embodiment 11, wherein the spiral is configured as an octagonal spiral.

[0130] Embodiment 14: The device of Embodiment 11, wherein the shape comprises a leaf-shaped geometry, and wherein the spiral defines a plurality of leaves configured to form the leaf-shaped geometry.

[0131] Embodiment 15: The apparatus of Embodiment 12, wherein one or more of the plurality of leaves comprises an outwardly directed vertex adjacent to an inwardly directed vertex of at least one leaf.

[0132] Embodiment 16: A device according to Embodiment 12, wherein one or more leaves of the plurality of leaves include an outward-pointing vertex, which is located between a first inward-pointing vertex adjacent to the outward-pointing vertex and a second inward-pointing vertex adjacent to the outward-pointing vertex.

[0133] Example 17: A device according to any one of Examples 1 to 16, wherein the spiral includes a distal portion, a middle portion and a proximal portion, wherein the distal portion includes the distal end of the first slender body, wherein the distal portion, the middle portion and the proximal portion define a distal diameter, a middle diameter and a proximal diameter, respectively, wherein the anti-rotation feature includes the middle diameter, and wherein the middle diameter is smaller than the distal diameter and the proximal diameter.

[0134] Example 18: The device of Example 17, wherein the distal diameter is equal to the proximal diameter.

[0135] Embodiment 19: The device of any of Embodiments 1-18, wherein the anti-rotation feature comprises a pitch of the one or more coils of the helix at the first portion of the helix.

[0136] Embodiment 20: The device of Embodiment 19, wherein the pitch of the one or more coils of the helix at the first portion is smaller than the pitch of the one or more coils of the helix at the second portion of the helix.

[0137] Embodiment 21: The device according to Embodiment 20, wherein the first portion is distal to the second portion.

[0138] Embodiment 22: The device of any of Embodiments 1-16, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates a varying pitch between adjacent coils.

[0139] Embodiment 23: The device of any of Embodiments 1 to 16, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates alternating peaks and troughs in the longitudinal direction.

[0140] Embodiment 24: A device according to any of Embodiments 1 to 16, wherein the anti-rotation feature includes undulations of the one or more coils, wherein the undulations produce alternating peaks and troughs, and longitudinally adjacent peaks and troughs are aligned to produce at least one location of reduced pitch.

[0141] Embodiment 25: The device of Embodiment 24, wherein at least one position where the pitch is reduced is spirally located between two positions having a larger pitch than the reduced pitch.

[0142] Embodiment 26: The device of Embodiment 24, wherein at least one location where the pitch decreases is spirally located between two locations where the pitch increases.

[0143] Embodiment 27: The device of Embodiment 24, wherein at least one position where the pitch is reduced is a position having a local minimum pitch that is spirally located between two positions having a local maximum pitch.

[0144] Embodiment 28: A device according to Embodiment 22, wherein the undulation is sinusoidal.

[0145] Embodiment 29: The device of any one of Embodiments 1 to 28, wherein the first elongated body and the second elongated body are wound in the same direction. .

[0146] Embodiment 30: The device of any one of Embodiments 1 to 28, wherein the first elongated body and the second elongated body are wound in different directions.

[0147] Embodiment 31: The device of any one of Embodiments 1 to 30, wherein the first elongated body is located within an interior space defined by the second elongated body and is substantially concentric with the second elongated body.

[0148] Embodiment 32: A device according to any one of Embodiments 1 to 31, wherein the second elongated body is configured to elastically deform through the tissue toward the distal end of the implantable medical device as the distance between the distal end and the tissue decreases so as to maintain contact with the tissue without penetrating the tissue.

[0149] Embodiment 33: A device comprising: an elongated shell extending from a proximal end of the shell to a distal end of the shell, the elongated shell being configured to be fully implanted in a first chamber of a heart, the first chamber of the heart having wall tissue; a first electrode extending distally from the distal end of the elongated shell, the first electrode comprising: a distal end of the first electrode, the distal end being configured to penetrate from the first chamber into wall tissue of a second chamber of the heart separated from the first chamber; and a first elongated body defining a helix extending to the distal end of the first electrode, the helix having an anti-rotation feature configured to resisting rotation of the first electrode within the wall tissue of the second chamber or within the wall tissue of the first chamber; a second electrode, the second electrode extending from the distal end of the slender shell, wherein the second electrode is separated from the first electrode; a second slender body, the second slender body extending distally from the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body; and a signal generating circuit, the signal generating circuit being within the slender shell, the signal generating circuit being coupled to the first electrode and the second electrode, wherein the signal generating circuit is configured to deliver cardiac pacing to the second chamber via the first electrode and to deliver the cardiac pacing to the first chamber via the second electrode.

[0150] Embodiment 34: A device according to Embodiment 33, wherein the second electrode is disposed on the second slender body.

[0151] Embodiment 35: The device according to any one of Embodiments 33 and 34, wherein the second elongated body is configured to flexibly maintain contact with the wall tissue of the first chamber without the second elongated body penetrating the wall tissue of the first chamber.

[0152] Embodiment 36: The device of any one of Embodiments 33 to 35, wherein the anti-rotation feature is configured to resist rotation of the first electrode due to movement of the wall tissue of the second chamber.

[0153] Example 37: The device according to any one of Examples 33 to 36, wherein the distal end of the first electrode is configured to penetrate into the patient's ventricular myocardium, and wherein the second slender body is configured to flexibly maintain contact with the patient's atrial endocardium.

[0154] Embodiment 38: A device according to any one of Embodiments 33 to 37, wherein the second elongated body is configured as a partial helix.

[0155] Embodiment 39: The device of any of Embodiments 33 to 38, wherein the anti-rotation feature comprises a shape of the helix relative to a plane orthogonal to the longitudinal axis of the elongated housing.

[0156] Embodiment 40: A device according to Embodiment 39, wherein the shape is equilateral.

[0157] Embodiment 41: A device according to any of Embodiments 39 and 40, wherein the shape includes multiple edges connected at multiple vertices.

[0158] Example 42: The device of Example 41, wherein the plurality of vertices are configured to improve penetration of the tissue by the distal end of the first elongated body.

[0159] Embodiment 43: The device of any one of Embodiments 39 to 42, wherein the shape comprises a geometric shape, and wherein the spiral defines the geometric shape.

[0160] Embodiment 44: A device according to Embodiment 43, wherein the spiral is configured as a hexagonal spiral.

[0161] Embodiment 45: A device according to Embodiment 43, wherein the spiral is configured as an octagonal spiral.

[0162] Embodiment 46: A device according to Embodiment 43, wherein the shape includes a leaf-shaped geometry, and wherein the spiral defines a plurality of leaves configured to form the leaf-shaped geometry.

[0163] Embodiment 47: An apparatus according to Embodiment 46, wherein one or more of the plurality of leaves comprises an outwardly directed vertex adjacent to at least one inwardly directed vertex.

[0164] Embodiment 48: A device according to Embodiment 46, wherein one or more leaves of the plurality of leaves include an outward-pointing vertex, which is located between a first inward-pointing vertex adjacent to the outward-pointing vertex and a second inward-pointing vertex adjacent to the outward-pointing vertex.

[0165] Example 49: A device according to any one of Examples 33 to 48, wherein the spiral includes a distal portion, a middle portion and a proximal portion, wherein the distal portion includes the distal end of the first slender body, wherein the distal portion, the middle portion and the proximal portion define a distal diameter, a middle diameter and a proximal diameter, respectively, wherein the anti-rotation feature includes the middle diameter, and wherein the middle diameter is smaller than the distal diameter and the proximal diameter.

[0166] Example 50: A device according to Example 49, wherein the distal diameter is equal to the proximal diameter.

[0167] Embodiment 51: The device of any of Embodiments 33-50, wherein the anti-rotation feature comprises a pitch of the helix at a first portion of the helix.

[0168] Embodiment 52: A device according to Embodiment 51, wherein the pitch of the spiral at the first portion of the spiral is smaller than the pitch of the spiral at the second portion of the spiral.

[0169] Example 53: A device according to Example 52, wherein the first portion is distal to the second portion.

[0170] Embodiment 54: The device of any of Embodiments 33 to 48, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates a varying pitch between adjacent coils.

[0171] Embodiment 55: The device of any one of Embodiments 33 to 48, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates alternating peaks and troughs in the longitudinal direction.

[0172] Embodiment 56: A device according to any one of Embodiments 33 to 48, wherein the anti-rotation feature includes undulations of the one or more coils, wherein the undulations produce alternating peaks and troughs, and longitudinally adjacent peaks and troughs are aligned to produce at least one location of reduced pitch.

[0173] Embodiment 57: A device according to Embodiment 56, wherein at least one position where the pitch is reduced is spirally located between two positions having a larger pitch than the reduced pitch.

[0174] Embodiment 58: A device according to Embodiment 56, wherein at least one position where the pitch is reduced is spirally located between two positions where the pitch is increased.

[0175] Embodiment 59: The device of Embodiment 56, wherein at least one position where the pitch is reduced is a position having a local minimum pitch that is spirally located between two positions having a local maximum pitch.

[0176] Embodiment 60: A device according to Embodiment 54, wherein the undulation is sinusoidal.

[0177] Embodiment 61: The device according to any one of Embodiments 33 to 60, wherein the first electrode and the second electrode are wound in the same direction.

[0178] Embodiment 62: The device according to any one of Embodiments 33 to 60, wherein the first electrode and the second electrode are wound in different directions.

[0179] Embodiment 63: The device of any one of Embodiments 33 to 62, wherein the first electrode is located in an interior space defined by the second electrode and is substantially concentric with the second electrode.

[0180] Embodiment 64: A device according to any one of Embodiments 33 to 63, wherein the second slender body is configured to elastically deform toward the distal end of the slender shell through the wall tissue of the first chamber as the distance between the distal end of the slender shell and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber.

[0181] Embodiment 65: A device according to any one of Embodiments 33 to 64, wherein the second slender body extends from a first end to a second end, and the first end and the second end are attached to the slender shell.

[0182] Embodiment 66: A device according to any one of Embodiments 33 to 65, wherein the second elongated body extends from a first end attached to the elongated shell to a free second end that bends rearwardly toward the elongated shell.

[0183] Embodiment 67: The device of any one of Embodiments 33 to 66, wherein the length of the first electrode is in the range of about 3 millimeters (mm) to about 12 mm.

[0184] Embodiment 68: According to any one of embodiments 33 to 65, the device also includes a third electrode extending from the distal end of the slender shell, wherein the third electrode is substantially similar to the second electrode.

[0185] Embodiment 69: The device according to any one of Embodiments 33 to 68, further comprising at least one steroid eluting element configured to elute steroids near at least one of the first electrode or the second electrode.

[0186] Example 70: A device according to any of Examples 33 and 69, wherein the device comprises an implantable pacemaker configured to be fully implanted within the first chamber of the heart.

[0187] Embodiment 71: A method, the method comprising: delivering cardiac pacing from a device to a heart, wherein the device comprises: an elongated shell extending from a proximal end of the shell to a distal end of the shell, the elongated shell being configured to be completely implanted in a first chamber of the heart, the first chamber of the heart having wall tissue; a first electrode extending distally from the distal end of the elongated shell, the first electrode comprising: a distal end of the first electrode, the distal end being configured to penetrate into wall tissue of a second chamber of the heart separated from the first chamber of the heart; and a first elongated body, the first elongated body comprising: a distal end of the first electrode, the distal end being configured to penetrate into wall tissue of a second chamber of the heart separated from the first chamber of the heart. The elongated body defines a helix having an anti-rotation feature configured to resist rotation of the first electrode within the wall tissue of the second chamber; a second electrode extending from the distal end of the elongated shell, wherein the second electrode is separated from the first electrode; and a second elongated body configured to extend from the distal end of the implantable medical device, wherein the second elongated body is separated from the first elongated body, wherein delivering the cardiac pacing includes: delivering the cardiac pacing to the second chamber via the first electrode; and delivering the cardiac pacing to the first chamber via the second electrode.

[0188] Embodiment 72: The method of Embodiment 71, wherein the anti-rotation feature is configured to resist rotation of the first electrode due to movement of the wall tissue of the second chamber.

[0189] Embodiment 73: A method according to any one of Embodiments 71 and 72, wherein the second electrode is disposed on the second slender body.

[0190] Example 74: A method according to any one of Examples 71 to 73, wherein the distal end of the first electrode is configured to penetrate into the patient's ventricular myocardium, and wherein the second elongated body is configured to flexibly maintain contact with the patient's atrial endocardium.

[0191] Embodiment 75: A method according to any one of Embodiments 71 to 74, wherein the second elongated body is configured as a partial helix.

[0192] Embodiment 76: The method of any one of Embodiments 71 to 75, wherein the anti-rotation feature comprises a shape of the helix relative to a plane orthogonal to the distal end of the elongated housing.

[0193] Embodiment 77: A method according to Embodiment 76, wherein the shape is equilateral.

[0194] Embodiment 78: A method according to any one of Embodiments 76 and 77, wherein the shape includes multiple edges connected at multiple vertices.

[0195] Embodiment 79: The method of any one of Embodiments 76 to 78, wherein the plurality of vertices are configured to improve penetration of the tissue by the distal end of the first elongated body.

[0196] Embodiment 80: A method according to any one of Embodiments 76 to 79, wherein the shape comprises a geometric shape, and wherein the spiral defines the geometric shape.

[0197] Embodiment 81: A method according to Embodiment 80, wherein the spiral is configured as a hexagonal spiral.

[0198] Embodiment 82: A method according to Embodiment 80, wherein the spiral is configured as an octagonal spiral.

[0199] Embodiment 83: The method of Embodiment 82, wherein the shape comprises a leaf-shaped geometry, and wherein the spiral defines a plurality of leaves configured to form the leaf-shaped geometry.

[0200] Embodiment 84: A method according to Embodiment 83, wherein one or more leaves of the plurality of leaves include an outward-pointing vertex adjacent to at least one inward-pointing vertex.

[0201] Embodiment 85: A method according to Embodiment 83, wherein one or more leaves among the plurality of leaves include an outward-pointing vertex, which is located between a first inward-pointing vertex adjacent to the outward-pointing vertex and a second inward-pointing vertex adjacent to the outward-pointing vertex.

[0202] Example 86: A method according to any one of Examples 71 to 85, wherein the spiral includes a distal portion, a middle portion and a proximal portion, wherein the distal portion includes the distal end of the first slender body, wherein the distal portion, the middle portion and the proximal portion define a distal diameter, a middle diameter and a proximal diameter, respectively, wherein the anti-rotation feature includes the middle diameter, and wherein the middle diameter is smaller than the distal diameter and the proximal diameter.

[0203] Example 87: A method according to Example 86, wherein the distal diameter is equal to the proximal diameter.

[0204] Embodiment 88: The method of any one of Embodiments 71 to 87, wherein the anti-rotation feature comprises a pitch of the helix of the first portion of the helix.

[0205] Embodiment 89: A method according to Embodiment 88, wherein the pitch of the spiral at the first portion of the spiral is smaller than the pitch of the spiral at the second portion of the spiral.

[0206] Embodiment 90: A method according to Embodiment 89, wherein the first portion is distal to the second portion.

[0207] Embodiment 91: The method of any one of Embodiments 71 to 85, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates a varying pitch between adjacent coils.

[0208] Embodiment 92: The method of any one of Embodiments 71 to 85, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates alternating peaks and troughs in the longitudinal direction.

[0209] Embodiment 93: A method according to Embodiment 92, wherein at least one position where the pitch is reduced is spirally located between two positions having a larger pitch than the reduced pitch.

[0210] Embodiment 94: A method according to Embodiment 92, wherein at least one position where the pitch is reduced is spirally located between two positions where the pitch is increased.

[0211] Embodiment 95: A method according to Embodiment 92, wherein at least one position where the pitch is reduced is a position with a local minimum pitch that is spirally located between two positions with local maximum pitches.

[0212] Embodiment 96: A method according to Embodiment 91, wherein the undulation is sinusoidal.

[0213] Embodiment 97: The method of any one of Embodiments 71 to 96, wherein the first elongated body and the second elongated body are wound in the same direction.

[0214] Embodiment 98: The method of any one of Embodiments 71 to 97, wherein the first elongated body and the second elongated body are wound in different directions.

[0215] Embodiment 99: The method of any one of Embodiments 71 to 98, wherein the first electrode is located in an interior space defined by the second elongated body and is substantially concentric with the second electrode.

[0216] Embodiment 100: A method according to any one of Embodiments 71 to 99, wherein the second slender body is configured to elastically deform toward the distal end of the slender shell through the wall tissue of the first chamber as the distance between the distal end of the slender shell and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber.

[0217] Embodiment 101: The method of any one of Embodiments 71 to 100, wherein the second electrode extends from a first end to a second end, the first end and the second end being attached to the elongated housing.

[0218] Embodiment 102: The method of any one of Embodiments 71 to 100, wherein the second electrode extends from a first end attached to the elongated shell to a free second end bent rearwardly toward the elongated shell.

[0219] Embodiment 103: The method according to any one of Embodiments 71 to 102, wherein the length of the first electrode is in the range of about 3 millimeters (mm) to about 12 mm.

[0220] Embodiment 104: The method of any one of Embodiments 71 to 103, further comprising a third electrode extending from the distal end of the elongated shell, wherein the third electrode is substantially similar to the second electrode.

[0221] Embodiment 105: The method according to any one of Embodiments 71 to 104, further comprising at least one steroid eluting element configured to elute the steroid near at least one of the first electrode or the second electrode.

[0222] Embodiment 106: A method, comprising: forming a first slender body into one or more coils of a spiral, wherein at least one of the one or more coils defines an anti-rotation feature, which is configured to resist rotation of the spiral within the patient's tissue; disposing the spiral on a distal end of an implantable medical device so that the spiral extends distally from the distal end; and disposing a second slender body on the distal end of the implantable medical device, wherein the second slender body is separated from the first slender body, and wherein the second slender body is configured to flexibly maintain contact with the tissue without penetrating the tissue.

[0223] Embodiment 107: The method according to Embodiment 106, wherein the first elongated body comprises a first electrode.

[0224] Embodiment 108: A method according to any one of Embodiments 106 and 107, wherein the second elongated body comprises a second electrode.

[0225] Embodiment 109: The method of any one of Embodiments 106 to 108, wherein the anti-rotation feature comprises a shape of the helix relative to a plane orthogonal to the distal end of the implantable medical device.

[0226] Embodiment 110: The method of Embodiment 109, wherein the shape is equilateral.

[0227] Embodiment 111: A method according to embodiments 109 and 110, wherein the shape includes multiple edges connected at multiple vertices.

[0228] Embodiment 112: The method of any one of Embodiments 109 to 111, wherein the shape comprises a geometric shape, and wherein the spiral defines the geometric shape.

[0229] Embodiment 113: The method of Embodiment 112, wherein the spiral is configured as a hexagonal spiral.

[0230] Embodiment 114: The method of Embodiment 112, wherein the spiral is configured as an octagonal spiral.

[0231] Embodiment 115: The method of Embodiment 112, wherein the shape comprises a leaf-shaped geometry, and wherein the spiral defines a plurality of leaves configured to form the leaf-shaped geometry.

[0232] Embodiment 116: A method according to Embodiment 115, wherein one or more leaves of the plurality of leaves include an outward-pointing vertex adjacent to at least one inward-pointing vertex.

[0233] Embodiment 117: A method according to claim 115, wherein one or more leaves of the plurality of leaves include an outward-pointing vertex, which is located between a first inward-pointing vertex adjacent to the outward-pointing vertex and a second inward-pointing vertex adjacent to the outward-pointing vertex.

[0234] Embodiment 118: The method according to any one of claims 106 to 117, wherein the spiral comprises a distal portion, a middle portion, and a proximal portion, wherein the distal portion comprises the distal end of the first slender body, wherein the distal portion, the middle portion, and the proximal portion define a distal diameter, a middle diameter, and a proximal diameter, respectively, wherein the anti-rotation feature comprises the middle diameter, and wherein the middle diameter is smaller than the distal diameter and the proximal diameter.

[0235] Embodiment 119: The method according to Embodiment 118, wherein the distal diameter is equal to the proximal diameter.

[0236] Embodiment 120: The method of any one of Embodiments 106 to 119, wherein the anti-rotation feature comprises a pitch of the one or more coils of the helix at the first portion of the helix.

[0237] Embodiment 121: The method of Embodiment 120, wherein the pitch of the one or more coils of the spiral at the first portion is smaller than the pitch of the one or more coils of the spiral at the second portion of the spiral.

[0238] Embodiment 122: The method according to embodiment 121, wherein the first portion is distal to the second portion.

[0239] Embodiment 123: The method of any one of Embodiments 106 to 117, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates a varying pitch between adjacent coils.

[0240] Embodiment 124: The method of any one of Embodiments 106 to 117, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates alternating peaks and troughs in the longitudinal direction.

[0241] Embodiment 125: A method according to any one of Embodiments 106 to 117, wherein the anti-rotation feature comprises undulations of the one or more coils, wherein the undulations produce alternating peaks and troughs, and longitudinally adjacent peaks and troughs are aligned to produce at least one position where the pitch is reduced.

[0242] Embodiment 126: A device according to Embodiment 125, wherein at least one position where the pitch is reduced is spirally located between two positions where the pitch is larger than the reduced pitch.

[0243] Embodiment 127: A device according to Embodiment 125, wherein at least one position where the pitch is reduced is spirally located between two positions where the pitch is increased.

[0244] Embodiment 128: The device of Embodiment 125, wherein at least one position where the pitch is reduced is a position having a local minimum pitch that is spirally located between two positions having a local maximum pitch.

[0245] Embodiment 129: A device according to Embodiment 123, wherein the undulation is sinusoidal.

[0246] Embodiment 130: A fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, wherein at least one of the one or more coils defines an anti-rotation feature, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises a leaf-shaped geometry, and wherein the helix defines a plurality of leaves configured to form the leaf-shaped geometry.

[0247] Embodiment 131: A device according to Embodiment 130, wherein one or more of the leaves include an outwardly directed vertex adjacent to at least one inwardly directed vertex.

[0248] Embodiment 132: A device according to Embodiment 130, wherein one or more of the leaves include an outward-pointing vertex that is located between a first inward-pointing vertex adjacent to the outward-pointing vertex and a second inward-pointing vertex adjacent to the outward-pointing vertex.

[0249] Embodiment 133: A fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, the helix comprising a distal portion, a middle portion, and a proximal portion; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises the middle portion having a smaller diameter than the distal portion and the proximal portion.

[0250] Embodiment 134: A fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils, the helix comprising a distal portion, a middle portion, and a proximal portion; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises the middle portion having a smaller pitch than the distal portion and the proximal portion.

[0251] Embodiment 135: A fixation device comprising: a first slender body configured to extend distally from a distal end of an implantable medical device, the first slender body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils; and an anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises a varying pitch of the helix, the varying pitch being produced by an undulating configuration of the one or more coils of the helix.

[0252] Embodiment 136: The device of Embodiment 135, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation produces a varying pitch between adjacent coils.

[0253] Embodiment 137: The device of any of Embodiments 135 and 136, wherein the anti-rotation feature comprises an undulation of the one or more coils, wherein the undulation creates alternating peaks and troughs in the longitudinal direction.

[0254] Embodiment 138: A device according to any one of Embodiments 135 to 137, wherein the anti-rotation feature includes undulations of the one or more coils, wherein the undulations produce alternating peaks and troughs, and longitudinally adjacent peaks and troughs are aligned to produce at least one position where the pitch is reduced.

[0255] Embodiment 139: A device according to Embodiment 138, wherein at least one position where the pitch is reduced is spirally located between two positions having a larger pitch than the reduced pitch.

[0256] Embodiment 140: A device according to Embodiment 138, wherein at least one position where the pitch is reduced is spirally located between two positions where the pitch is increased.

[0257] Embodiment 141: The apparatus of claim 138, wherein at least one position where the pitch is reduced is a position having a local minimum pitch that is spirally located between two positions having a local maximum pitch.

[0258] Various embodiments have been described. These and other embodiments are within the scope of the following claims.

Claims

1. A fixing device, comprising: A first elongated body configured to extend distally from a distal end of an implantable medical device, the first elongated body comprising: a distal end configured to penetrate into tissue of a patient; and a helix having one or more coils; and An anti-rotation feature defined by the one or more coils, the anti-rotation feature being configured to resist rotation of the helix within the tissue, wherein the anti-rotation feature comprises a varying pitch of the helix, the varying pitch being produced at least in part by an undulating configuration of the one or more coils of the helix.

2. The device of claim 1, wherein the undulating configuration produces a varying pitch between adjacent coils.

3. The device according to any one of claims 1 and 2, wherein the undulating configuration produces alternating peaks and troughs in the longitudinal direction.

4. The device of any one of claims 1 to 3, wherein the undulating configuration produces alternating peaks and troughs, and longitudinally adjacent peaks and troughs are aligned to produce at least one location where the pitch is reduced.

5. The device of claim 4, wherein the at least one position where the pitch is reduced is located helically between two positions having a larger pitch than the reduced pitch.

6. The device of claim 4, wherein the at least one position where the pitch is reduced is spirally located between two positions where the pitch is increased.

7. The apparatus of claim 4, wherein at least one position where the pitch is reduced is a position having a local minimum pitch, the position being located spirally between two positions having a local maximum pitch.

8. The device of any one of claims 1 to 7, wherein the anti-rotation feature further comprises a shape of the helix relative to a plane orthogonal to a longitudinal axis of the implantable medical device.

9. The device of claim 8, wherein the shape is equilateral.

10. The apparatus of any one of claims 8 and 9, wherein the shape comprises a plurality of edges connected at a plurality of vertices.

11. The device of claim 10, wherein a plurality of vertices are configured to improve penetration of the tissue by the distal end of the first elongated body.

12. The device of any one of claims 8 to 11, wherein the shape comprises a geometric shape, and wherein the helix defines the geometric shape.

13. The apparatus of claim 8, wherein the shape comprises a leaf geometry, and wherein the spiral defines a plurality of leaves configured to form the leaf geometry.

14. The apparatus of claim 13, wherein one or more of the plurality of leaves comprises an outwardly directed vertex adjacent to at least one inwardly directed vertex.

15. A device according to any one of claims 1 to 14, wherein the spiral includes a distal portion, a middle portion and a proximal portion, wherein the distal portion includes the distal end of the first slender body, wherein the distal portion, the middle portion and the proximal portion define a distal diameter, an intermediate diameter and a proximal diameter, respectively, wherein the anti-rotation feature also includes the intermediate diameter, and wherein the intermediate diameter is smaller than the distal diameter and the proximal diameter.

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