Medical device fixation with anti-rotation feature

Abstract

A fixation device includes a first elongate body extending distally from a distal end of an implantable medical device and a second elongate body extending distally from the distal end of the implantable medical device. The first elongate body includes a helix having one or more coils, wherein a distal end of the helix is configured to penetrate into tissue of a patient. The second elongate body is configured to flexibly maintain contact with the tissue without penetrating the tissue, and wherein the second elongate body is disposed on the distal end at a separation angle away from an electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second end of the second elongate body.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 369,456, 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 configured 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 into the heart within a blood vessel to position the electrodes relative to the heart tissue. Some pacemakers are sized to be implanted entirely 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 and having 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. In some examples, the fixation device includes a first elongated body extending from a distal end of the device and configured to penetrate the tissue of the patient. The first elongated body may define a spiral. In some examples, the fixation device is embodied as one or more electrodes of the implantable medical device. In some examples, the anti-rotation feature includes a second elongated body extending distally from the distal end of the device. The second elongated body may have a free end and may be positioned away from the one or more electrodes of the implantable medical device at an angle determined by a user. The second elongated body may resist reverse rotation of the spiral out of the tissue, for example by compressing the tissue.

[0006] In some examples, the anti-rotation feature can improve electrical conductivity between tissue and one or more electrodes of an implantable medical device. The anti-rotation feature (e.g., the second elongated body) can reduce the likelihood and / or frequency of loss of electrical connection between the tissue and the one or more electrodes and promote more consistent delivery of electrical signals from the one or more electrodes to the tissue.

[0007] 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 configured to penetrate the patient's tissue. The implantable medical device may also include one or more anti-rotation features (e.g., a second elongated body) that prevent the device from rotating. In addition to avoiding device displacement, the anti-rotation features 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. In some examples, anti-rotation features in such implantable medical devices can reduce oscillations of the device and increase the reliability of electrical contact between the second electrode and the wall tissue.

[0008] In one example, the present disclosure relates to a fixation device comprising: a first elongated body extending distally from a distal end of an implantable medical device, the first elongated body comprising: a helix having one or more coils, wherein the distal end of the helix is ​​configured to penetrate into tissue of a patient; and a second elongated body extending distally from the distal end of the implantable medical device, wherein the second elongated body is separated from the first elongated body, wherein the second elongated body is connected to the implantable medical device at a first position and is farthest from the implantable medical device at a second position when not stressed, wherein the second elongated body is configured to flexibly maintain contact with tissue without penetrating tissue, and wherein the second elongated body is disposed on the distal end of the implantable medical device at a separation angle away from an electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second position of the second elongated body.

[0009] In another example, the present disclosure is directed to a device comprising: an elongated shell extending from a proximal end to a distal end, 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 first elongated body defining a helix, wherein the helix is ​​configured to penetrate into wall tissue of a second chamber of the heart separated from the first chamber of the heart; a second electrode disposed on the distal end of the elongated shell; a second elongated body extending distally from the distal end of the elongated shell, wherein the second elongated body is connected to the distal end at a first position and when unstressed The second position is farthest from the distal end of the slender shell, wherein the second slender body is separated from the first electrode and the second electrode, wherein the second slender body is configured to maintain contact between the second electrode and the wall tissue of the first chamber without the second slender body penetrating the wall tissue of the first chamber, and wherein the second slender body is disposed on the distal end at a separation angle away from the electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second position of the second slender body; and a signal generating circuit, which is 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 cardiac pacing to the first chamber via the second electrode.

[0010] 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 to a distal end, 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 a distal end of the elongated shell, the first electrode comprising: a first elongated body defining a helix; a second electrode disposed on the distal end of the elongated shell; a second elongated body extending from the distal end of the elongated shell, wherein the second elongated body is connected to the distal end at a first position and is distally spaced from the elongated shell at a second position when not stressed The lateral end is farthest, wherein the second slender body is separated from the first electrode and the second electrode, and wherein the second slender body is configured to flexibly maintain contact between the second electrode and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber through the second electrode or the second slender body, wherein the second slender body is disposed on the distal end at a separation angle away from the electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and a second position of the second 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 delivering cardiac pacing includes: delivering cardiac pacing to the second chamber via the first electrode; and delivering cardiac pacing to the first chamber via the second electrode.

[0011] In another example, the present disclosure relates to a fixation device comprising: a first slender body extending distally from a distal end of an implantable medical device, the first slender body comprising: a helix having one or more coils, wherein the distal end of the helix is ​​configured to penetrate into the patient's tissue; and a 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, wherein the second slender body is configured to apply a proximally directed force on a portion of the distal end of the implantable medical device, and wherein the second slender body is disposed on the distal end of the implantable medical device away from an electrode disposed on the distal end of the implantable medical device, so that action of the second slender body tends to push the electrode into contact with the tissue.

[0012] 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

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] Figure 4 It is implanted at the target implantation site Figures 1 to 3 Conceptual image of the device.

[0018] 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.

[0019] Fig. 6A It is shown Figures 1 to 5C A conceptual diagram of a partial view of the device.

[0020] Figure 6B It is shown Figures 1 to 5C A conceptual diagram of another partial view of the device.

[0021] Figure 7 is a flow chart illustrating an exemplary process for deploying an exemplary apparatus. DETAILED DESCRIPTION

[0022] 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 and 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.

[0023] 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 (such as the triangle of Koch in the patient's heart 102) in the right atrium (RA) of 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.

[0024] The device 104 includes a distal end 110 and a proximal end 116. The distal end 110 includes a first electrode 112, a second electrode 118, and an elongated body 114. The first electrode 112 may define a helical shape, e.g., Figure 1 As shown. The first electrode 112 extends from the distal end 110 and can penetrate the wall tissue of the first chamber (e.g., the RA in the example shown) into the wall tissue of the second chamber (e.g., the ventricular myocardium 108 of the LV in the example shown). The elongated body 114 extends from the distal end 110 and is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber through the elongated body 114 or the second electrode 118. When the first electrode 112 penetrates the wall tissue of the first chamber, the second electrode 118 can contact the wall tissue of the first chamber, and the elongated body 114 flexibly maintains contact with the wall tissue of the first chamber.

[0025] Figure 1 The configuration of electrodes 112 and 118 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 118 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 implantation region 106 to sense and / or pace the RA and ventricles, but the device having an electrode configuration according to an example 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 the region 106 or another region, and the first electrode 112 may extend into tissue of the LV or interventricular septum (e.g., myocardial tissue) to facilitate, for example, the delivery of AV synchronized pacing. In addition, the device having an electrode configuration according to an example 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.

[0026] 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 implanted medical device, such as an implanted stimulator or implanted lead that is configured to be secured at any location or tissue in the body.

[0027] 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, MP3 5N (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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Each of the first electrode 112, the second electrode 118, and the elongated body 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 except via the first end (e.g., is a free end). The first electrode 112 may include one or more coatings (e.g., an electrically insulating coating) configured to define the first electroactive region 216, or the first electrode 112 may otherwise define the first electroactive region 216. In some examples, the first electroactive region 216 may be closer to the second end of the first electrode 112, such as the distal end. Figure 2 In some examples, first electroactive region 216 includes the distal end of electrode 112. Second electrode 118 may include one or more coatings configured to define second electroactive region 218 on an outer surface of electrode 118. Figure 2 As shown, the second electroactive region 218 forms a ring around the steroid eluting element or therapeutic substance dispensing device, for example, as described with respect to Fig. 6A and Figure 6B The second electrode 118 may be a button electrode, a spring electrode, or any other suitable type or shape of electrode.

[0034] The first electrode 112 and the second electrode 118 can be formed of a conductive material such as titanium, platinum, iridium, tantalum, stainless steel, or alloys thereof. The first electrode 112 and the second electrode 118 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 118, 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 118, 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.

[0035] In some examples, first electrode 112 and second electrode 118 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.

[0036] exist Figure 2 In some examples, the first electrode 112 is in the form of a spiral. The first electrode 112 can be an elongated body defining a spiral. In some examples, the spiral is an object having a three-dimensional shape that resembles a wire uniformly wound in a single layer around a cylindrical surface or a conical surface or a mandrel, such that if the surface were unfolded into a plane, the wire would be a straight line. The second electrode 118 is disposed on the distal end 204 and can include a button electrode, such as Figure 2 , or any other suitable type or shape of electrode. In some examples, the device 104 can have a plurality of second electrodes 118 (e.g., two or more second electrodes 118) disposed on the distal end 204 of the housing 202. The plurality of second electrodes 118 can be equally spaced around the circumference of the distal end 204. In some examples, the second electrode can be disposed at a user-selected angle away from the first end of the first electrode 112.

[0037] The elongated body 114 includes a ramp portion configured to contact the patient's tissue, such as the wall tissue of the chamber in which the device 104 is implanted. The ramp portion of the elongated body 114 can be configured as a partial spiral, such as a spiral that does not make a complete rotation around the circumference of a cylindrical surface or a conical surface. The elongated body 114 can be formed of a conductive material (e.g., titanium, platinum, iridium, tantalum, or an alloy thereof), and / or formed of a non-conductive material. At least a portion of the elongated body 114 (e.g., the ramp portion of the elongated body 114) can be coated with an electrically insulating coating, such as polyparaxylene, polyurethane, silicone, epoxy, or other insulating coatings. In some examples, the elongated body 114 can be formed of a memory metal (e.g., nitinol, platinum, titanium, MP35N, etc.) and / or a memory polymer (e.g., silicone, polyurethane, polyetheretherketone (PEEK), etc.) or other materials. In some examples, the elongated body 114 can be configured to maintain contact with tissue without significant deflection (eg, less than or equal to 2 millimeters (mm) of deflection).

[0038] The elongated body 114 can be disposed over and at least partially within the recess 115. When the distance between adjacent tissue and the distal end 204 decreases, the elongated body 114 can deflect into the recess 115, for example, to maintain contact with the tissue without penetrating the tissue.

[0039] The elongated body 114 may be an anti-rotation feature. The elongated body 114 may increase compression of the tissue and / or increase friction or other securing forces between the tissue and the device 104 and / or the electrode 112. The increase in securing force may be sufficient to resist rotation of the first electrode 112 due to movement of 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 elongated body 114 may resist forces up to about 5 ounces of force inches (ozf.in) (e.g., up to about 0.035 Newton meters (Nm)). The amount of force exerted by the tissue on the first electrode 112 and / or the amount of force exerted by the elongated body 114 on the tissue may vary based on the movement of the heart 102, the movement of the device 104, the movement of fluids within the heart 102, the size of the heart 102, etc.

[0040] In some examples, the first electrode 112 may include one or more additional anti-rotation features. The additional anti-rotation features may include the shape of the first electrode 112, the size of the first electrode 112 (e.g., outer diameter, pitch, etc.), one or more features disposed on the outer surface of the first electrode 112, etc. The shape and / or size of the first electrode 112 may include the geometry of the first electrode 112, the varying diameter configuration of the first electrode 112, the varying pitch configuration of the first electrode 112, the waveform configuration of the first electrode 112, or any combination thereof. 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.).

[0041] like Figure 2 As shown, the first electrode 112 can be a right-handed wound helix and the elongated body 114 can be a right-handed wound partial helix, but in other examples, the handedness of the electrodes can be switched or the electrodes can each have a different handedness from one another. Winding the elongated body 114 in the same direction as the first electrode 112 can reduce resistance to a clinician inserting and / or removing the device 104 while increasing resistance to rotation of the device 104 due to movement of tissue and / or movement of the heart 102. Figure 2In some examples, the spirals and partial spirals defined by the first electrode 112 and the elongated body 114, respectively, have the same pitch, but 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.). Such a geometric shape may be equilateral.

[0042] The size and shape of first electrode 112 and second electrode 118 may also vary to enhance tissue contact of first electroactive region 216 and second electroactive region 218. For example, first electrode 112 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. In some examples, second electrode 118 may have an outer surface that varies in size and shape (e.g., an oval outer surface, an outer surface with a larger diameter, etc.) to enhance tissue contact of second electroactive region 218.

[0043] The size and shape of first electrode 112 and / or elongated body 114 may be determined at least in part by stiffness requirements. For example, stiffness requirements may vary based on anticipated implantation requirements, including the tissue in which the electrode is implanted or in contact, and how long the device 104 is intended to be implanted.

[0044] 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 first electrode 112 may have a maximum diameter at its base where it intersects with the housing distal end 204. In such examples, the outer diameter of the spiral defined by 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.

[0045] 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 elongated body 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 can be configured to maintain a distance between the first electroactive region 216 and the housing distal end 204.

[0046] 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 or coincident with 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 incompressible. 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 subsides, 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 or coincident with the longitudinal axis 212), the first electrode 112 maintains a straight linear configuration as shown.

[0047] In some examples, the second electrode 118 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 118 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 / or the second electrode 118 at different times for ventricular functionality or atrial functionality, respectively. In some examples, the first electrode 112 and the second electrode 118 can be paired with each other at different polarities for atrial functionality and ventricular functionality.

[0048] In some examples, the second electrode 118 can be configured as an atrial cathode electrode for delivering pacing pulses in conjunction with the electrode 210 to, for example, atrial tissue at the target implant area 106. The second electrode 118 and the electrode 210 can also be used to sense an atrial P wave for controlling atrial pacing pulses (delivered in the absence of a sensed P wave), and for controlling atrial synchronized ventricular pacing pulses delivered using the first electrode 112 as a cathode and the electrode 210 as a return anode.

[0049] At the distal end 204, the device 104 includes a distal fixation assembly 214 that includes a first electrode 112, a second electrode 118, an elongated body 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 118 and the elongated body 114 can be configured to contact the patient's atrial endocardium. In some examples, the distal fixation assembly 214 can include more or fewer electrodes than two electrodes. In some examples, the distal fixation assembly 214 can include one or more second electrodes 118 along the housing distal end 204. For example, the distal fixation assembly 214 can include two or three electrodes configured for atrial functionality, such as the second electrode 118, and the three electrodes can be substantially similar or different from each other. The spacing between the plurality of second electrodes 118 can be equal or unequal distances. The second electrode 118 can be individually selectively coupled to the sensing circuit and / or pacing circuit enclosed by the housing 202 to function as an anode with the first electrode 112 or as an atrial cathode electrode, or can be electrically common and not individually selectable. In some examples of the distal fixation assembly 214, a fixation element (not shown) having similar shape and mechanical properties, but without an electroactive region or electrode formed thereon or carried thereon, can be employed in place of the first electrode 112. In such examples, the electroactive region 216 can be positioned on a separate member and / or on the housing 202.

[0050] The elongated body 114 is configured to flexibly maintain contact between the second electrode 118 and wall tissue of the cardiac chamber in which the device 104 is implanted (e.g., the RA endocardium), 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.

[0051] In order to flexibly maintain contact with the wall tissue, the elongated body 114 can be flexible and configured to have spring-like properties. In some examples, the elongated body 114 can be relatively flexible in some portions and relatively inflexible in other portions. For example, the elongated body 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 elongated body 114 away from the distal end 204 of the housing 202. In this way, the elastic deformation and spring bias can maintain consistent contact of the elongated body 114 with the wall tissue of the chamber (e.g., the right atrium) in which the device is implanted.

[0052] The elongated body 114 can maintain consistent contact between the second electrode 118 and the wall tissue, for example, by pushing the second electrode 118 toward the wall tissue. The consistent contact between the second electrode 118 and the wall tissue can improve conductivity and the delivery of electrical signals from the second electrode 118 to the wall tissue. In some examples, where the device 104 is an implantable pacing device, the consistent contact between the second electrode 118 and the wall tissue can reduce and / or maintain the pacing threshold of a chamber (e.g., the right atrium) of the heart 102. The elongated body 114 can be disposed at a separation angle away from the second electrode 118 around the longitudinal axis 212 to increase the compressive force between the second electrode 118 and the wall tissue. In some examples, the separation angle can be an angle between the second electrode 118 and the second end (e.g., the free end) of the elongated body 114. The separation angle can be about 180 degrees, or between about 15 degrees and about 180 degrees. In some examples, a larger separation angle can improve contact under more adverse conditions (e.g., if the device 104 oscillates within the heart 102).

[0053] As described herein, flexibly maintaining contact can refer to that the electrode and / or the elongated body can move relative to the housing 202. For example, the electrode and / or the elongated body can be configured to be elastically deformed as described above. In some examples, the electrode (e.g., the second electrode 118) 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.

[0054] 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 118, which can be as shown relative to Figure 1 and Figure 2 For example, as with respect to Figure 1 and Figure 2As 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 118 extends from the distal end 204 of the housing 202 and can be configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber by the second electrode. The second electrode 118 can flexibly maintain contact in this manner by virtue of a spring biased distally away from the housing 202 and / or due to the action of the elongated body 114 or otherwise.

[0055] 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 .

[0056] The signal generating circuit 306 generates electrical stimulation signals, such as cardiac pacing pulses. The switching circuit 302 is coupled to the electrodes 112, 118, 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 stimulation signals from the signal generating circuit 306 to a selected combination of electrodes 112, 118, 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 generating circuit 306 as a cathode, and couple the second electrode 118 or one or both of the electrodes 210 to the signal generating circuit 306 as an anode. As another example, to pace the RA, the switch circuit 302 may couple the second electrode 118 that flexibly maintains contact with the RA endocardium to the signal generating circuit 306 as a cathode and couple one or both of the first electrode 112 or electrode 210 to the signal generating circuit 306 as an anode.

[0057] The switch circuit 302 may also selectively couple the sensing circuit 304 to a selected combination of the electrodes 112, 118, 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, 118, and / or 210. For example, the switch circuit 302 may couple each of the first electrode 112 and the second electrode 118 (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.

[0058] 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.

[0059] 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 accomplish communication via radio frequency (RF) communication techniques, such as via an antenna (not shown).

[0060] 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.

[0061] Figure 4 1 is a conceptual diagram of a device 104 implanted at a target implantation region 106. A first electrode 112 can be inserted (e.g., in a manner similar to rotating and advancing a threaded screw) such that 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.

[0062] 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.

[0063] As the first electrode 112 is advanced into the tissue, the distance between the elongated body 114 and the atrial endocardium 404 decreases until the elongated body 114 contacts and can press against the surface of the atrial endocardium 404. The elongated body 114 can press against the surface of the atrial endocardium 404 and compress the wall tissue. The compression of the wall tissue can increase the friction between the elongated body 114 and the wall tissue and prevent the first electrode 112 from rotating due to tissue movement of the heart 102 (e.g., movement of the ventricular myocardium 108, the atrial myocardium 406, the central fibrous body 402, etc.). The elongated body 114 pressing against the cardiac tissue can cause the cardiac tissue to engage with the second electrically active region 218 of the second electrode 118, which is disposed at a separation angle away from the elongated body 114. The second electrode 118 maintains contact with the atrial endocardium 404 through the first electrode 112 and the elongated body 114. The second electrode 118 can be prevented from retracting from the surface of the atrial endocardium 404 by the first electrode 112 and the force exerted on the atrial endocardium 404 by the elongated body 114. As described herein, the elongated body 114 is also configured to flexibly maintain contact with the atrial endocardium 404. In some examples, the elongated body 114 can be elastically deformed toward the distal end 204 of the housing 202 and into the recess 115, and has a spring bias that pushes the elongated body 114 distally from the distal end 204.

[0064] In some examples, elongated body 114 can be the only anti-rotation feature of device 104. In some examples, device 104 can have one or more additional anti-rotation features, for example, defined and / or disposed on first electrode 112. The distance that first electrode 112 extends from housing 202 can be selected so that first electrically active region 216 reaches an appropriate depth in the tissue layers to reach the target pacing and sensing site, in this case, in ventricular myocardium 108, without puncturing all the way into an adjacent ventricle.

[0065] 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 118 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 may be less than 2 mm, and may be 1 mm or less, or even 0.6 mm or less.

[0066] 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. 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 505 of the distal end 204) defines a recess 115 (e.g., a recessed channel) to receive at least a portion of the elongated body 114 when the elongated body 114 is elastically deformed toward the housing 202. When the elongated body 114 is partially or completely deformed into the recess 115, the second electroactive region 218 of the second electrode 118 disposed on the distal end 204 can maintain contact with the tissue surface.

[0067] In some examples, such as Figure 5AAs shown, the distal end 204 of the housing 202 includes, for example, a peripheral region surrounding the first electrode 112. The elongated body 114 and the second electrode 118 may be disposed in the peripheral region of the distal end 204.

[0068] In some examples, the elongated body 114 and the second electrode 118 can maintain contact with tissue as the degree of deformation of the elongated body 114 toward the housing 202 varies. The elongated body 114 can be spring biased to an undeformed position, and deformation of the elongated body 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 elongated body 114 and the second electrode 118 disposed at a separation angle away from the elongated body 114 and more specifically the second electroactive region 218 of the second electrode 118 against the cardiac tissue. When the elongated body 114 pushes a portion of the housing 202 distally away from the adjacent cardiac tissue, the first electrode 112 can act as a fulcrum or pivot, whereby the second electrode 118 is pushed in a proximal direction toward the adjacent cardiac tissue. The deformation of the elongated body 114 can vary with the movement of the heart. Due at least in part to the ability of the elongated body 114 to deform, e.g., change during the cardiac cycle, the second electrode 118 can maintain consistent contact with tissue and provide pacing to the heart, e.g., due to the angle of separation between the second electrode 118 and the elongated body 114.

[0069] The elongated body 114 may extend from a first end 508 to a second end 510. The first end 508 may be connected to the distal end 204 of the housing 202. In some examples, such as Figure 5A As shown, the second end 510 can be connected to the distal end 204 or can be a free end (e.g., free floating or cantilevered). In some examples, the second end 510 may include a protrusion extending proximally toward the distal end 204, such as Fig. 6A The second end 510 and / or the protrusion may be free floating to facilitate removal of the elongated body 114 from the tissue, for example, by allowing removal of the elongated body 114 from overgrown tissue in the recess 115.

[0070] Figure 5B According to one or more aspects of the present disclosure Figure 5A A conceptual diagram of a side view of device 104 is shown. Figure 5C is a conceptual diagram of a top view of device 104 according to one or more aspects of the present disclosure.

[0071] like Figure 5BAs shown, the elongated body 114 may include a ramp portion 512 extending distally away from the distal end 204. The recess 115 in the housing 202 may include a corresponding notch so that the ramp portion 512 can be completely disposed within the recess 115. In some examples, the proximal end of the ramp portion 512 can engage tissue and increase resistance between the elongated body 114 and the tissue, thereby causing the device 104 to resist rotation.

[0072] like Figure 5C As shown, the second electrode 118 can be separated from the elongated body 114 by a separation angle 514 about the longitudinal axis 212. In some examples, such as Figure 5C 1 , angle 514 is the angle between second electrode 118 (e.g., the central axis of second electrode 118) and second end 510 of elongated body 114. Angle 514 may be about 180 degrees, or between about 15 degrees and about 180 degrees. In some examples, where device 104 includes two or more second electrodes 118, angle 514 may be between second end 510 of elongated body 114 and one or more of second electrodes 118. In some examples, each of the plurality of second electrodes 118 may be separated from second end 510 of elongated body 114 by at least angle 514.

[0073] Fig. 6A It is shown Figures 1 to 5C A conceptual illustration of a partial view of device 104 with a cutout showing recess 115 . Figure 6B It is shown Figures 1 to 5C 1 is a conceptual illustration of a partial view of another exemplary device 104 with a cutout showing a recess 115 . Fig. 6A An exemplary elongated body 114 is shown having a protrusion 606 disposed at the second end 510 and configured to be disposed within the recess 602 in the recess 115 . Figure 6B Another exemplary elongated body 114 is shown without the protrusion 606 and the recessed hole 602 in the recess 115 .

[0074] like Fig. 6A and Figure 6B As shown, the first end 508 of the elongated body 114 is attached to the header 502 and connected (eg, electrically connected) to the feed-through. Fig. 6A As shown, at the opposite end of the elongated body 114, the second end 510 of the elongated body 114 is bent back toward the device 104 and forms a protrusion 606. For example, when the elongated body 114 is deformed toward the distal end 204 of the housing 202, the protrusion 606 may be able to move into the recess 602 within the recess 115. The second electrode 118 may maintain contact with the tissue while the protrusion 606 is pushed into the recess 602 due to the deformation of the elongated body 114 with the movement of the heart.

[0075] In some examples, during removal of the device 104 from the heart 102 by the clinician, the protrusion 606 may be deflected distally toward the distal end 204 (e.g., due to the spring bias of the elongated body 114 and / or overgrown tissue within the recess 115 and / or the recess 602). The overgrown tissue within the recess 115 and / or the recess 602 may be due to natural growth of tissue (e.g., around a foreign body). The protrusion 606 may be deflected distally toward the distal end 204 and allow the overgrown tissue to exit the recess 115 and / or the recess 602, thereby allowing removal of the device 104 without requiring the clinician to remove the overgrown tissue. In some examples, such as Figure 6B As shown, the elongated body 114 may not include the protrusion 606 at the second end 510, and may further facilitate removal of the device 104 and / or overgrown tissue.

[0076] As discussed herein, the first electrode 112 and the elongated body 114 can have different right-handed spiral shapes. For example, the spiral of the first electrode 112 and the portion of the spiral defined by the elongated body 114 can both be right-handed. 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. As the distance between the elongated body 114 and the tissue decreases due to the right-handed rotation of the first electrode 112, the tissue will gradually contact the sloped portion 512 of the elongated body 114 similar to being advanced along a ramp (at Figure 5C ), and the slope shape of the slope portion 512 will gradually deform toward the housing 202, such as compression.

[0077] In some examples, the first electrode 112 includes a helix having a first pitch, and the ramp portion 114 of the elongated body 114 is a partial helix having a second pitch. The first pitch of the helix of the first electrode 112 can be the same, substantially similar, or different than the second pitch of the partial helix of the elongated body 114. In some examples, the elongated body 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 an interior space defined by the elongated body 114 and is substantially concentric with the elongated body 114.

[0078] 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 electrodes 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 power supply of the IMD 104 associated with the delivery of the stimulation.

[0079] In some examples, an IMD as described herein, such as IMD 104, can include, for example, one or more steroid eluting elements 604A-604C (collectively, "steroid eluting elements 604') disposed on distal end 204. Steroids can reduce inflammation of a patient's tissue resulting from interaction with the IMD. Steroid eluting element 604 can be configured to elute one or more steroids into tissue proximate element 604 over time. In some examples, steroid eluting element 604 includes one or more monolithic controlled release devices (MCRDs). In some examples, steroid eluting element 604 can be a therapeutic substance dispensing device.

[0080] In some examples, the IMD includes one or both of a first steroid eluting element 604A and a second steroid eluting element 604B, the first steroid eluting element being configured to elute one or more steroids into tissue proximate to the first electrode 112, and the second steroid eluting element being configured to elute one or more steroids into tissue proximate to the elongated body 114. The IMD 104 includes a steroid eluting element 604 at the distal end 204 of the housing 202, e.g., included in, attached to, or formed on the head 502. The steroid eluting element 604 can elute one or more steroids into wall tissue proximate to the elongated body 114. In some examples, such as Fig. 6A and Figure 6B As shown, the second steroid eluting element 604B may be disposed within the recess 115. In some examples, one or more steroid eluting elements 604 may be disposed on the second electrode 118 (eg, on the second electroactive region 218).

[0081] Figure 7 104 ( Figure 1 ) to describe Figure 7 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.

[0082] The clinician may insert the device 104 into a single first chamber of the heart 102 (702). The first chamber of the heart 102 may be the right atrium, the left atrium, the right ventricle, or the left ventricle. The clinician may insert the device 104 into the first chamber via a delivery tool connected to the device 104 (e.g., connected to the delivery tool interface member 208). The clinician may advance the first electrode 112 extending distally from the housing 202 of the device 104 to penetrate the wall tissue of the first chamber of the heart 102 and enter the wall tissue of the second chamber (704). In some examples, advancing the first electrode 112 includes positioning the distal end of the first electrode 112 (e.g., the first electroactive region 216) within the patient's ventricular myocardium 108. The clinician may advance the first electrode 112 by rotating the device 104 clockwise or counterclockwise within the first chamber (depending on how the first electrode 112 is wound).

[0083] The clinician can cause the device 104 to establish and maintain contact between the elongated body 114 and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber (706). In some examples, the elongated body 114 can flexibly maintain contact with the wall tissue. In some examples, flexibly maintaining contact with the wall tissue of the first chamber with the elongated body 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 elongated body 114 includes deforming the elongated body 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 115 receives at least a portion of the elongated body 114 as it elastically deforms back toward the elongated housing 202. In some examples, the spring bias of the elongated body 114 pushes the elongated body 114 away from the housing 202 and into consistent contact with the wall tissue of the first chamber. The elongated body 114 can maintain a second electrode 118 disposed on the distal end 204 of the housing 202 in consistent contact with the wall tissue of the first chamber (e.g., the patient's atrial endocardium 402), for example, at least in part due to the spring bias of the elongated body 114. The second electrode 118 can be disposed at a separation angle 514 about the longitudinal axis 212 away from the elongated body 114 (e.g., away from the second end 510 of the elongated body 114).

[0084] When the device 104 is implanted within cardiac tissue, the one or more anti-rotation features defined resist rotation of the device 104 due to movement of the cardiac tissue. 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. The one or more anti-rotation features may include an elongated body 114 that maintains contact with the wall tissue of the first chamber. The elongated body 114 can increase compression of the wall tissue, which resists rotation of the device 104 due to movement of the wall tissue.

[0085] 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 118 (708). The device 104 may deliver cardiac pacing to the first chamber and / or the second chamber via the first electrode 112, the second electrode 118, and / or one or more other electrodes (e.g., electrode 210) of the device 104.

[0086] 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, merged, 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.

[0087] In one or more examples, the described techniques can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can 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 that corresponds 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).

[0088] 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.

[0089] 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.

[0090] Embodiment 1: A fixation device, comprising: a first slender body extending distally from a distal end of an implantable medical device, the first slender body comprising: a helix having one or more coils, wherein the distal end of the helix is ​​configured to penetrate into the patient's tissue; and a 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, wherein the second slender body is connected to the implantable medical device at a first position and is farthest from the implantable medical device at a second position when not stressed, wherein the second slender body is configured to flexibly maintain contact with the tissue without penetrating the tissue, and wherein the second slender body is disposed on the distal end of the implantable medical device at a separation angle away from an electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second position of the second slender body.

[0091] Embodiment 2: The device of Embodiment 1, wherein the first elongated body comprises a first electrode, and wherein the electrode disposed on the distal end of the implantable medical device comprises a second electrode.

[0092] Embodiment 3: A device according to any one of Embodiments 1 and 2, wherein the implantable medical device comprises an implantable pacemaker configured to be completely implanted in a first chamber of the patient's heart.

[0093] Embodiment 4: A device according to any one of Embodiments 1 to 3, wherein the implantable medical device is configured to be implanted in the first chamber of the patient's heart, wherein the first slender body is configured to penetrate the wall tissue of the second chamber of the heart, and wherein the second slender body is configured to flexibly maintain contact between the electrode and the wall tissue of the first chamber of the heart.

[0094] Example 5: The device according to Example 4, wherein the distal end of the first slender body is configured to penetrate into the patient's ventricular myocardium, and wherein the second slender body is configured to flexibly maintain contact between the electrode and the patient's atrial endocardium.

[0095] Embodiment 6: The device according to any one of embodiments 1 to 5, wherein the second elongated body is configured as a partial helix.

[0096] Embodiment 7: A device according to Embodiment 6, wherein the partial helix is ​​wound in the same direction as the helix of the first slender body.

[0097] Embodiment 8: The device according to embodiment 7, wherein the partial helix and the helix of the first slender body are wound in a counterclockwise direction.

[0098] Embodiment 9: A device according to any one of embodiments 1 to 8, wherein the distal end of the implantable medical device defines a first recess, and the first recess is configured to retain at least a portion of the second elongated body while the second elongated body flexibly maintains contact with the tissue.

[0099] Example 10: A device according to Example 9, wherein the second slender body also includes a protrusion arranged at the second position of the second slender body, and wherein the distal end of the implantable medical device is also defined by a second recess within the first recess, wherein the second recess is configured to retain the protrusion of the second slender body.

[0100] Embodiment 11: The device according to any one of Embodiments 9 and 10, wherein the distal end of the implantable medical device further comprises a therapeutic substance dispensing device disposed within the first recess.

[0101] Embodiment 12: The device of embodiment 11, wherein the therapeutic substance dispensing device comprises a monolithic controlled release device.

[0102] Embodiment 13: The device according to any one of Embodiments 11 and 12, wherein the implantable medical device further comprises a plurality of therapeutic substance dispensing devices disposed on the distal end of the implantable medical device.

[0103] Embodiment 14: A device according to any one of embodiments 1 to 13, wherein the second position of the second slender body includes the distal-most end of the second slender body.

[0104] Embodiment 15: The device of any one of Embodiments 1 to 14, wherein the separation angle is 15 degrees or greater.

[0105] Embodiment 16: A device according to any one of embodiments 1 to 15, wherein the separation angle is 180 degrees.

[0106] Embodiment 17: The device of any one of Embodiments 1 to 16, wherein the second elongated body is configured to maintain the electrode in contact with the tissue.

[0107] Embodiment 18: The device of any one of Embodiments 1 to 17, wherein the first elongated body and the second elongated body comprise a metal alloy.

[0108] Embodiment 19: A device according to Embodiment 18, wherein the second elongated body comprises a nickel-titanium alloy.

[0109] Embodiment 20: The device of any one of Embodiments 1 to 19, 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.

[0110] Embodiment 21: A device according to any one of Embodiments 1 to 20, wherein the second slender 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 to maintain contact with the tissue without penetrating the tissue.

[0111] Embodiment 22: The device according to any one of Embodiments 1 to 21, wherein the second electrode is a button electrode.

[0112] Embodiment 23: A device according to any one of Embodiments 1 to 22, wherein the second elongated body is disposed on a peripheral region of the distal end of the implantable medical device.

[0113] Embodiment 24: The device according to any one of Embodiments 1 to 23, wherein the second electrode is disposed on a peripheral region of the distal end of the implantable medical device.

[0114] Embodiment 25: The device according to any one of Embodiments 1 to 24, wherein the first elongated body is disposed on the distal end of the implantable medical device, between the second elongated body and the second electrode.

[0115] Embodiment 26: The device according to any one of embodiments 1 to 25, wherein the second elongated body is configured to push the second electrode toward the tissue of the patient.

[0116] Embodiment 27: The device according to Embodiment 26, wherein the second elongated body is configured to push the first portion of the distal end of the implantable medical device away from the tissue of the patient while the second elongated body pushes the second electrode toward the tissue of the patient.

[0117] Embodiment 28: A device comprising: an elongated shell extending from a proximal end to a distal end, 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 first elongated body defining a spiral, wherein the spiral is configured to penetrate into the wall tissue of a second chamber of the heart separated from the first chamber of the heart; a second electrode disposed on the distal end of the elongated shell; a second elongated body extending distally from the distal end of the elongated shell, wherein the second elongated body is connected to the distal end at a first position and is detached from the elongated shell at a second position when not stressed. the distal end of the implantable medical device, wherein the second elongated body is separated from the first electrode and the second electrode, wherein the second elongated body is configured to maintain contact between the second electrode and the wall tissue of the first chamber without the second elongated body penetrating the wall tissue of the first chamber, and wherein the second elongated body is disposed on the distal end at a separation angle away from the electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second position of the second elongated body; and a signal generating circuit within the elongated 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.

[0118] Embodiment 29: A device according to Embodiment 28, wherein the second electrode comprises a button electrode.

[0119] Embodiment 30: The device of any one of Embodiments 28 and 29, wherein the second elongated body is configured to resist rotation of the first electrode due to movement of the wall tissue of the first chamber.

[0120] Example 31: The device according to any one of Examples 28 to 30, wherein the first electrode is configured to penetrate into the patient's ventricular myocardium, and wherein the second electrode is configured to flexibly maintain contact between the second electrode and the patient's atrial endocardium.

[0121] Embodiment 32: The device of any one of Embodiments 28 to 31, wherein the second elongated body is configured as a partial helix.

[0122] Embodiment 33: A device according to Embodiment 32, wherein the partial helix is ​​wound in the same direction as the helix of the first slender body.

[0123] Embodiment 34: The device according to Embodiment 33, wherein the partial helix and the helix of the first elongated body are wound in a counterclockwise direction.

[0124] Embodiment 35: A device according to any one of Embodiments 28 to 34, wherein the distal end of the slender shell defines a first recess, which is configured to retain at least a portion of the second slender body while the second slender body flexibly maintains contact between the second electrode and the wall tissue of the first chamber.

[0125] Example 36: A device according to Example 35, wherein the second slender body also includes a protrusion arranged at the second position of the second slender body, wherein the distal end of the slender shell also defines a second recess within the first recess, and wherein the second recess is configured to retain the protrusion of the second slender body.

[0126] Embodiment 37: The device of any one of Embodiments 35 and 36, wherein the distal end of the elongated housing further comprises a plurality of therapeutic substance dispensing devices.

[0127] Embodiment 38: The device of Embodiment 37, wherein one or more therapeutic substance dispensing devices of the plurality of therapeutic substance dispensing devices are disposed within the first recess.

[0128] Embodiment 39: A device according to any one of Embodiments 28 to 38, wherein the second position of the second slender body includes the distal-most end of the second slender body.

[0129] Embodiment 40: A device according to Embodiment 39, wherein the separation angle is 15 degrees or greater.

[0130] Embodiment 41: A device according to any one of Embodiments 28 to 40, wherein the separation angle is 180 degrees.

[0131] Embodiment 42: The device of any one of Embodiments 28 to 41, wherein the second elongated body is configured to maintain the second electrode in contact with the wall tissue of the first chamber.

[0132] Embodiment 43: The device of any one of Embodiments 28 to 42, wherein the first elongated body and the second elongated body comprise a metal alloy.

[0133] Embodiment 44: A device according to Embodiment 43, wherein the second slender body comprises a nickel-titanium alloy.

[0134] Embodiment 45: The device of any one of Embodiments 28 to 44, 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.

[0135] Embodiment 46: A device according to any one of Embodiments 28 to 45, wherein the second slender body is configured to elastically deform from the wall tissue of the first chamber toward the distal end of the slender shell as the distance between the distal end and the wall tissue of the first chamber decreases, so as to maintain contact between the second electrode and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber.

[0136] Embodiment 47: A device according to any one of Embodiments 28 to 46, wherein the second slender body is disposed on a peripheral region of the distal end of the slender shell.

[0137] Embodiment 48: The device of any one of Embodiments 28 to 47, wherein the second electrode is disposed on a peripheral region of the distal end of the elongated shell.

[0138] Embodiment 49: The device of any one of Embodiments 28 to 48, wherein the first elongated body is disposed on the distal end of the elongated housing between the second elongated body and the second electrode.

[0139] Embodiment 50: The device according to any one of Embodiments 1 to 49, wherein the second elongated body is configured to push the second electrode toward the tissue of the patient.

[0140] Embodiment 51: A device according to Embodiment 50, wherein the second elongated body is configured to push the first portion of the distal end of the implantable medical device away from the tissue of the patient while the second elongated body pushes the second electrode toward the tissue of the patient.

[0141] Embodiment 52: A method, the method comprising: delivering cardiac pacing from a device to a heart, wherein the device comprises: a slender shell extending from a proximal end to a distal end, the slender 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 slender shell, the first electrode comprising: a first slender body defining a helix; a second electrode disposed on the distal end of the slender shell; a second slender body extending from the distal end of the slender shell, wherein the second slender body is connected to the distal end at a first position and is farthest from the distal end of the slender shell at a second position when unstressed, wherein the second slender body A slender body is separated from the first electrode and the second electrode, and wherein the second slender body is configured to flexibly maintain contact between the second electrode and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber through the second electrode or the second slender body, wherein the second slender body is disposed on the distal end at a separation angle away from the electrode disposed on the distal end of the implantable medical device, wherein the separation angle includes an angle between the electrode and the second position of the second slender body; and a signal generating circuit, which is within the slender shell and is coupled to the first electrode and the second electrode, wherein delivering cardiac pacing includes: delivering cardiac pacing to the second chamber via the first electrode; and delivering cardiac pacing to the first chamber via the second electrode.

[0142] Embodiment 53: A method according to Embodiment 52, wherein the second electrode comprises a button electrode.

[0143] Embodiment 54: The method of any one of Embodiments 52 and 53, wherein the second elongated body is configured to resist rotation of the first electrode due to movement of the wall tissue of the first chamber.

[0144] Example 55: According to any one of Examples 52 to 54, the method further includes: penetrating the patient's ventricular myocardium with the first electrode of the device; and placing the second electrode in contact with the patient's atrial endocardium.

[0145] Embodiment 56: A method according to any one of Embodiments 52 to 55, wherein the second elongated body is configured as a partial helix.

[0146] Embodiment 57: A method according to Embodiment 56, wherein the partial helix is ​​wound in the same direction as the helix of the first slender body.

[0147] Embodiment 58: A method according to Embodiment 57, wherein the partial helix and the helix of the first elongated body are wound in a counterclockwise direction.

[0148] Embodiment 59: A method according to any one of Embodiments 52 to 58, wherein the distal end of the slender shell defines a first recess, which is configured to retain at least a portion of the second slender body while the second slender body flexibly maintains contact between the second electrode and the wall tissue of the first chamber.

[0149] Example 60: A method according to Example 59, wherein the second slender body also includes a protrusion arranged at the second position of the second slender body, wherein the distal end of the slender shell also defines a second recess within the first recess, and wherein the second recess is configured to retain the protrusion of the second slender body.

[0150] Embodiment 61: The method of any one of Embodiments 59 and 60, wherein the distal end of the elongated shell further comprises a plurality of therapeutic substance dispensing devices.

[0151] Embodiment 62: A method according to any one of Embodiments 52 to 61, wherein the second position of the second slender body includes the distal-most end of the second slender body.

[0152] Embodiment 63: A method according to Embodiment 62, wherein the separation angle is 15 degrees or greater.

[0153] Embodiment 64: A method according to any one of Embodiments 52 to 63, wherein the separation angle is 180 degrees.

[0154] Embodiment 65: The method of any one of Embodiments 52 to 64, wherein the second elongated body is configured to maintain the second electrode in contact with the wall tissue of the first chamber.

[0155] Embodiment 66: The method of any one of Embodiments 52 to 65, wherein the first elongated body and the second elongated body comprise a metal alloy.

[0156] Embodiment 67: The method of Embodiment 66, wherein the second elongated body comprises a nickel-titanium alloy.

[0157] Embodiment 68: The method of any one of Embodiments 52 to 67, 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.

[0158] Embodiment 69: A method according to any one of Embodiments 52 to 68, wherein the second slender body is configured to elastically deform through the wall tissue of the first chamber toward the distal end of the slender shell as the distance between the wall tissue of the first chamber and the distal end decreases, so as to maintain contact between the second electrode and the wall tissue of the first chamber without penetrating the wall tissue of the first chamber.

[0159] Embodiment 70: A method according to any one of Embodiments 52 to 69, wherein the second elongated body is disposed on a peripheral region of the distal end of the implantable medical device.

[0160] Embodiment 71: The method according to any one of Embodiments 52 to 70, wherein the second electrode is disposed on a peripheral region of the distal end of the elongated shell.

[0161] Embodiment 72: The method of any one of Embodiments 52 to 71, wherein the first elongated body is disposed on the distal end of the elongated housing between the second elongated body and the second electrode.

[0162] Embodiment 73: The method of any one of Embodiments 52 to 72, wherein the second elongated body is configured to push the second electrode toward the tissue of the patient.

[0163] Embodiment 74: A method according to Embodiment 73, wherein the second elongated body is configured to push the first portion of the distal end of the implantable medical device away from the tissue of the patient while the second elongated body pushes the second electrode toward the tissue of the patient.

[0164] Embodiment 75: A fixation device comprising: a first elongated body extending distally from a distal end of an implantable medical device, the first elongated body comprising: a helix having one or more coils, wherein the distal end of the helix is ​​configured to penetrate into the patient's tissue; and a second elongated body extending distally from the distal end of the implantable medical device, wherein the second elongated body is separated from the first elongated body, wherein the second elongated body is configured to apply a proximally directed force on a portion of the distal end of the implantable medical device, and wherein the second elongated body is disposed on the distal end of the implantable medical device away from an electrode disposed on the distal end of the implantable medical device, so that the action of the second elongated body tends to push the electrode into contact with the tissue.

[0165] Example 76: A device according to Example 75, wherein the implantable medical device is configured to be implanted in a first chamber of the patient's heart, wherein the first slender body is configured to penetrate the wall tissue of a second chamber of the heart, and wherein the movement of the second slender body tends to push the electrode into contact with the wall tissue of the first chamber.

[0166] Example 77: The device of Example 76, wherein the distal end of the spiral is configured to penetrate into the patient's ventricular myocardium, and wherein the action of the second elongated body tends to push the electrode into contact with the patient's atrial endocardium.

[0167] Embodiment 78: A device according to any one of Embodiments 75 to 76, wherein the second slender body is configured as a partial helix.

[0168] Embodiment 79: A device according to Embodiment 78, wherein the partial helix is ​​wound in the same direction as the helix of the first slender body.

[0169] Embodiment 80: The device according to Embodiment 79, wherein the partial helix and the helix of the first slender body are wound in a counterclockwise direction.

[0170] Embodiment 81: A device according to any one of Embodiments 75 to 80, wherein the distal end of the implantable medical device defines a first recess, and the first recess is configured to retain at least a portion of the second slender body when a proximally directed force is applied to a portion of the distal end of the implantable medical device.

[0171] Embodiment 82: The device according to Embodiment 81, wherein the distal end of the implantable medical device further comprises a therapeutic substance dispensing device disposed within the first recess.

[0172] Embodiment 83: The device of Embodiment 82, wherein the therapeutic substance dispensing device comprises a monolithic controlled release device.

[0173] Embodiment 84: The device according to any one of Embodiments 82 and 83, wherein the implantable medical device further comprises a plurality of therapeutic substance dispensing devices disposed on the distal end of the implantable medical device.

[0174] Embodiment 85: A device according to any one of Embodiments 75 to 84, wherein the second elongated body is configured to maintain the electrode in contact with the tissue.

[0175] Embodiment 86: A device according to Embodiment 85, wherein the second slender body comprises a nickel-titanium alloy.

[0176] Embodiment 87: A device according to any one of Embodiments 75 to 86, wherein the first slender body is located in the interior space defined by the second slender body and is substantially concentric with the second slender body.

[0177] Embodiment 88: A device according to any one of Embodiments 75 to 87, wherein the second electrode is a button electrode.

[0178] Embodiment 89: A device according to any one of Embodiments 75 to 88, wherein the second elongated body is disposed on a peripheral region of the distal end of the implantable medical device.

[0179] Embodiment 90: A device according to any one of Embodiments 75 to 89, wherein the second electrode is disposed on a peripheral region of the distal end of the implantable medical device.

[0180] Embodiment 91: A device according to any one of Embodiments 75 to 90, wherein the first slender body is disposed on the distal end of the implantable medical device, located between the second slender body and the second electrode.

[0181] Embodiment 92: A device according to any one of Embodiments 75 to 91, wherein the second elongated body is configured to push the second electrode toward the tissue of the patient.

[0182] Embodiment 93: A device according to Embodiment 92, wherein the second elongated body is configured to push the first portion of the distal end of the implantable medical device away from the tissue of the patient while the second elongated body pushes the second electrode toward the tissue of the patient.

[0183] 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 extending distally from a distal end of the implantable medical device, the first elongated body comprising: a helix having one or more coils, wherein a distal end of the helix is ​​configured to penetrate into tissue of a patient; and A second elongated body extending distally from the distal end of the implantable medical device, wherein the second elongated body is separated from the first elongated body, wherein the second elongated body is configured to apply a proximally directed force on a portion of the distal end of the implantable medical device, and wherein the second elongated body is disposed on the distal end of the implantable medical device away from an electrode disposed on the distal end of the implantable medical device such that action of the second elongated body tends to push the electrode into contact with the tissue.

2. A device according to claim 1, wherein the implantable medical device is configured to be implanted in a first chamber of the patient's heart, wherein the first slender body is configured to penetrate the wall tissue of a second chamber of the heart, and wherein the action of the second slender body tends to push the electrode into contact with the wall tissue of the first chamber.

3. A device according to claim 2, wherein the distal end of the helix is ​​configured to penetrate into the patient's ventricular myocardium, and wherein the action of the second elongated body tends to push the electrode into contact with the patient's atrial endocardium.

4. The device according to any one of claims 1 to 2, wherein the second elongated body is configured as a partial helix.

5. The device of claim 4, wherein the partial helix is ​​wound in the same direction as the helix of the first elongated body.

6. A device according to any one of claims 1 to 5, wherein the distal end of the implantable medical device defines a first recess, and the first recess is configured to retain at least a portion of the second slender body when the second slender body applies the proximally directed force on the portion of the distal end of the implantable medical device.

7. The device of claim 6, wherein the distal end of the implantable medical device further comprises a therapeutic substance dispensing device disposed within the first recess.

8. The device according to any one of claims 1 to 7, wherein the second elongated body is configured to maintain the electrode in contact with the tissue.

9. The device according to any one of claims 1 to 8, wherein the first slender body is located in an interior space defined by the second slender body and is substantially concentric with the second slender body.

10. The device according to any one of claims 1 to 9, wherein the second electrode is a button electrode.

11. The device according to any one of claims 1 to 10, wherein the second elongated body is disposed on a peripheral region of the distal end of the implantable medical device.

12. The device according to any one of claims 1 to 11, wherein the second electrode is disposed on a peripheral region of the distal end of the implantable medical device.

13. The device according to any one of claims 1 to 12, wherein the first elongated body is disposed on the distal end of the implantable medical device between the second elongated body and the second electrode.

14. The device according to any one of claims 1 to 13, wherein the second elongated body is configured to push the second electrode toward the tissue of the patient.

15. The device of claim 14, wherein the second elongated body is configured to push a first portion of the distal end of the implantable medical device away from the tissue of the patient while the second elongated body pushes the second electrode toward the tissue of the patient.

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