Electrode with angled welding surface for implantable medical devices

Abstract

Described are electrode assemblies, implantable medical devices including electrode assemblies, and methods for use with electrode assemblies, where such electrode assemblies are designed to strategically deflect the mating feedthrough wire into an angled electrode welding surface, thereby ensuring intimate contact between the feedthrough wire and the electrode to facilitate proper lateral welding to the angled welding surface. Intimate contact between the feedthrough wire and the welding surface can assist with various joining technologies including laser beam welding, resistance welding, microtag welding, and so forth. Such electrode assemblies may be particularly suited to use within leadless pacemaker devices and other implantable devices whose compactness and form factors may pose challenges in assembly and manufacturing.

Description

ELECTRODE WITH ANGLED WELDING SURFACE FOR IMPLANTABLE MEDICAL DEVICES

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 760,186, filed February 19, 2025, the entire content of which is incorporated herein by reference.

[0002] This disclosure generally relates to welding of feedthrough wires to distal electrodes in implantable medical devices.

[0003] Implantable medical devices (IMDs), such as implantable pacemakers, cardioverters, defibrillators, and the like, provide therapeutic electrical stimulation to the heart. IMDs may provide pacing to address bradycardia, or pacing or shocks in order to terminate tachyarrhythmia, such as tachycardia or fibrillation. In some cases, the medical device may sense intrinsic depolarizations of the heart, detect arrhythmia based on the intrinsic depolarizations (or absence thereof), and control delivery of electrical stimulation to the heart if arrhythmia is detected based on the intrinsic depolarizations.

[0004] As the design of IMDs evolve to provide desired functionality in a compact package, difficulties can arise related to ease of assembly and manufacturability, particularly with respect to attaching feedthrough wires to electrodes and electrode assemblies. Certain designs and geometries may present additional challenges with respect to welding of these components.SUMMARY

[0005] The techniques of this disclosure generally relate to electrode assemblies for implantable medical devices, the electrode assemblies being designed to strategically deflect the mating feedthrough wire into an angled electrode welding surface, thereby ensuring intimate contact with the electrode to facilitate proper lateral welding of the feedthrough wire to the angled welding surface. Intimate contact between the feedthrough wire and the welding surface can assist with various joining technologies including laser beam welding, resistance welding, microtag welding, and so forth.

[0006] In one example, aspects of this disclosure relate to an implantable medical device having a housing that extends from a proximal end to a distal end along a main axis direction, in which the medical device includes a feedthrough wire extending through thehousing substantially along the main axis direction to an electrode assembly located near the distal end of the housing. The electrode assembly, which is configured to deliver electrical stimulation to and / or sense electrical activity from cardiac tissue when the implantable medical device is implanted, has a weld surface positioned to form an acute angle relative to the main axis and disposed to engage and maintain contact with the feedthrough wire. In certain aspects, the electrode assembly may further include a guide surface positioned proximally to the weld surface, the guide surface forming an angle relative to the main axis that is larger than the acute angle formed by the weld surface relative to the main axis. In certain aspects, the electrode assembly may include a chamber for containing a drug or other treatment to be administered to the cardiac tissue by the implantable medical device.

[0007] In another example, aspects of this disclosure relate to an electrode assembly for inclusion in an implantable medical device, where the electrode assembly includes a weld surface configured for laterally welding thererto a distal portion of a feedthrough wire, the weld surface being oriented at an acute angle relative to a main axis defined by a direction of extension of the feedthrough wire such that positioning of the weld surface in contact with the distal portion of the feedthrough wire bends the feedthrough wire to thereby create a bias that maintains intimate contact between the weld surface and the distal portion of the feedthrough wire.

[0008] In yet another example, aspects of this disclosure relate to a method for assembling an implantable medical device that includes a housing that extends from a proximal end to a distal end along a main axis direction. Such a method involves extending a feedthrough wire through the housing substantially along the main axis direction such that a distal end of the feedthrough wire terminates at a location near the distal end of the housing, installing an electrode assembly over the distal end of the feedthrough wire such that the distal end of the feedthrough wire engages with a weld surface of the electrode assembly, the weld surface forming an acute angle relative to the main axis direction to thereby maintain intimate contact between the weld surface and the feedthrough wire, and laterally welding the feedthrough wire to the weld surface from a direction orthogonal to the main axis direction. In certain aspects, welding includes laser welding, resistance welding, or microtag welding.

[0009] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 A is a conceptual diagram that illustrates an example implantable medical device that may provide a suitable environment for implementation of various aspects of the present disclosure.

[0011] FIG. IB is a conceptual cross-sectional diagram of a portion of the implantable medical device shown in FIG. 1 A.

[0012] FIG. 2A is a conceptual diagram that illustrates an example of an electrode assembly for an implantable medical device, the electrode assembly having an angled weld surface in accordance with various aspects of the present disclosure.

[0013] FIG. 2B is a conceptual cross-sectional diagram of the electrode assembly shown in FIG. 2A.

[0014] FIG. 2C is a conceptual bottom-up illustration of the electrode assembly shown in FIG. 2A.

[0015] FIG. 3 A is a conceptual diagram that illustrates installation of an electrode assembly in an implantable medical device, the electrode assembly having an angled weld surface in accordance with various aspects of the present disclosure.

[0016] FIG. 3B is a conceptual side-view illustration of portions of the electrode assembly shown in FIG. 3 A after installation, as viewed through lateral through holes in the housing of the implantable medical device.DETAILED DESCRIPTION

[0017] The design of IMDs, such as the leadless pacemakers available from Medtronic under the trade designation Micra™, may take into account several factors related to functionality and compactness that can pose challenges in assembly and manufacturing. For example, the accessibility of weld points between feedthrough wires and electrodes may be limited. Issues may further include ability to align, or to verify alignment, of feedthrough wires to electrodes, ability to weld without risking electrode wall damage orcontamination, pin shadowing leading to inconsistent welding, difficulty in deburring, and other such limitations that may lead to reduced yields during manufacturing.

[0018] Recognizing such challenges, various aspects of the present disclosure provide for distal electrode geometries in IMDs that are fashioned to promote consistent weldability. In particular, devices of the present disclosure include a surface angled relative to a major axis of a feedthrough wire so that the angled surface guides the feedthrough wire into proper position relative to the electrode, and ensures intimate contact between the feedthrough wire and the electrode during a lateral welding step. For example, the presence of the angled surface may result in a bend in the feedthrough wire during installation of the electrode, the bend in the feedthrough wire producing an opposing bias of the feedthrough wire against the angled surface that maintains intimate contact.

[0019] In general, the angled surface may form an acute angle with the main axis of the feedthrough wire, for example an angle greater than 0 degrees and up to 45 degrees, and in certain embodiments about 1 degrees to 30 degrees, preferably about 5 degrees to 15 degrees. In certain embodiments, the angled surface may form a curved shape such as a “U” or “V” shaped groove when viewed along the main axis of the feedthrough wire, thereby laterally containing the feedthrough wire within the groove, as well as fill material for the weld. In certain embodiments, a through hole may be provided in the housing of the IMD to facilitate easy of lateral welding of feedthrough wires to the angled weld surfaces of installed electrode assemblies, and in certain aspects to provide for visual inspection before and / or after performing such lateral welds. In certain embodiments, a through hole may be provided in the housing of the IMD to align with a through hole provided in the electrode assembly to thereby provide for trimming of any excess pin portion of the feedthrough wire protruding into a chamber of the electrode assembly, and in certain aspects to provide for visual inspection before and / or after performing such trimming.

[0020] Reference will now be made to the drawings, which depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawings fall within the scope of this disclosure. Like numbers used in the figures refer to like components, steps, and the like. However, it will be understood that the use of a reference character to refer to an element in a given figure is not intended to limit the element in another figure labeled with the same reference character. In addition, the use ofdifferent reference characters to refer to elements in different figures is not intended to indicate that the differently referenced elements cannot be the same or similar.

[0021] It will be apparent to one skilled in the art that elements or processes from one embodiment may be used in combination with elements or processes of the other embodiments, and that the possible embodiments of such devices and methods using combinations of features set forth herein is not limited to the specific embodiments shown in the Figures and / or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be recognized that timing of the processes and the size and shape of various elements herein may be modified but still fall within the scope of the present disclosure, although certain timings, one or more shapes and / or sizes, or types of elements, may be advantageous over others.

[0022] FIG. 1 A is a schematic diagram of an example IMD 100 that may be used with aspects of the present disclosure. IMD 100 may be a device such as a leadless pacemaker configured for treating heart conditions through sensing cardiac signals and / or delivering pacing therapy. IMD 100 may include a housing that defines a hermetically-sealed internal cavity in which internal components of the IMD 100 reside, such as a sensing circuit, therapy delivery circuit, control circuit, memory, telemetry circuit, other optional sensors, and a power source. The housing of IMD 100 may define a generally cylindrical shape, for example to facilitate catheter delivery, or may define a prismatic or other shape to perform the necessary functionality and utility. A helical fixation element 110 may be disposed at a distal end of the IMD 100 to facilitate in coupling or anchoring the IMD 100 into cardiac tissue. In certain embodiments, all or a portion of the fixation element 110 may also act as a tissue piercing electrode, for example for delivering of pacing energy to and / or sensing signals from the tissue.

[0023] One or more non-tissue piercing electrodes 140 may be provided at a distal body end of the IMD 100. Such non-tissue piercing distal electrode(s) 140 may operate to sense electrical activity at and / or deliver electrical stimulation to any suitable location in the heart, including within the right atrium, such as one or both of the AV node or nerves innervating the AV node. The electrode(s) 140 may be formed of an electrically conductive material, such as copper, platinum, iridium, or alloys thereof. An electrode 140 may be optionally capped with a cover 120, for example in embodiments where theelectrode 140 includes a chamber 122 for containing a drug or other substance for therapy. The cover 120 may provide a surface for electrode 140 that is intended to come into contact with cardiac tissue and to deliver the therapy. In certain aspects, the cover 120 on electrode 140 may be a TiN surface that is applied through a coating or sintering process. During implantation of the IMD 100, the fixation element 130 may be advanced into the cardiac tissue until at least one non-tissue piercing electrode 140 is positioned against, in intimate contact with, or in operative proximity to, a cardiac tissue surface for delivering AV nodal stimulation and / or sensing nerve activity from one or both of the AV node or nerves innervating the AV node.

[0024] FIG. IB is a schematic cross-sectional diagram of a distal portion IB of IMD 100, which is the portion indicated by box IB in FIG. 1A. Next to helical fixation element 110, which extends distally from the device, is an electrode assembly 140. The electrode assembly 140 includes an angled weld surface 142 to which feedthrough wire 160 may be welded. As shown, feedthrough wire 160 extends from a proximal portion of the IMD along a main axis 160A of the feedthrough wire 160 until it reaches angled surface 142 of electrode 140, at which point the feedthrough wire 160 exhibits a bend 162 due to the influence of the angled surface 142, which promotes intimate contact with the feedthrough wire 160. The angle 142a of angled surface 142 as measured relative to the main axis 160 A may be an acute angle, for example about 20 degrees or less, preferably between about 5 degrees and 15 degrees. Optionally, the electrode assembly 140 may include a guide surface 146 that is positioned proximally to the angled surface 142, for example to assist in the guiding of the feedthrough wire 160 to the angled surface 142, particularly during electrode installations in which the feedthrough wire 160 is misaligned. Generally, the guide surface 146 forms an angle with the main axis 160Athat is larger than the angle formed between the angled surface 142 and the main axis 160A.

[0025] Depending on the configuration of the electrode 140 and the length of the feedthrough wire 160, a pin portion 164 of the feedthrough wire 160 may partially extend through a pin hole aperture 124 in the electrode assembly 140 that opens into a chamber 122. The chamber 122 is a cavity that may be used to contain a drug or other substance for treatment or therapy. An auxiliary side aperture 144 may be provided in the electrode assembly 140 (and aligned with an opening in the housing of the IMD, if necessary) for access into the chamber 122 from the outside of the IMD. For example, auxiliary sideaperture 144 may be used to capture the pin portion 164 of the feedthrough wire 160 for trimming or to ensure proper positioning and / or completed installation of the electrode assembly 140.

[0026] A lateral weld aperture 134 may be provided in the housing of the IMD for providing access to welding devices and / or materials for the lateral welding of feedthrough wire 160 to angled weld surface 142 of electrode 140. In certain devices, it may be difficult to use a more conventional “top-down” weld process whereby the pin portion 164 of the feedthrough wire 160 is welded to the electrode assembly 140 at or around the pin hole 124. Accordingly, a through hole such as lateral weld aperture 134 may be provided to facilitate the lateral welding of feedthrough wire 160 to angled weld surface 142 of electrode 140. Lateral welding refers to the welding taking place from a direction that is substantially orthogonal to the main axis 160A. Any suitable welding technique may be used such as laser welding, resistance welding, and so forth.

[0027] FIG. 2A schematically shows an example of an electrode assembly 240 that includes an angled weld surface 242 in accordance with various aspects of the present disclosure. At a proximal end, electrode assembly 240 includes a guide surface 246 that is arranged to guide a feedthrough wire (not shown) to proper engagement with angled surface 242 during installation of the electrode assembly 240. At a distal end, electrode assembly 240 includes a chamber 222 that is accessible via lateral aperture 244. Electrode assembly 240 may be made of an electrically conductive material, such as copper, platinum, iridium, or alloys thereof (such as a Ptlr alloy), and may be fabricated by any suitable means including various machining techniques (such as micro-milling). The geometry of electrode assembly 240 may be produced without electro-discharge machining (EDM) and in a way that does not require significant deburring.

[0028] FIG. 2B is a schematic cross-sectional view of the electrode assembly 240 shown in FIG. 2 A, as viewed along line 2B. Angled weld surface 242 forms an angle 242a with main axis 260A. Main axis 260A defines the direction of extension of the feedthrough wire (not shown). Optional guide surface 246 may be provided proximal to the angled weld surface 242, with guide surface 246 forming an angle with the main axis 260Athat is larger than angle 242a. Optionally, a chamber 222 may be provided at the distal portion of the electrode assembly 240, for example to contain a steroid or other drug or treatment forapplication at the site of electrode engagement with heart tissue upon implantation of an IMD into which electrode 240 is incorporated.

[0029] Chamber 222 may be accessed via lateral aperture 244. A through hole 224 joins the proximal portion of electrode 240 to the chamber 222. The size of through hole 224 is preferably sufficient to allow a properly positioned feedthrough wire (not shown) to be inserted therethrough, potentially extending at least a small distance into chamber 222. Moreover, the through hole 224 may be sized to allow for a feedthrough wire to pass through while allowing for a sufficiently large trim variation. In certain aspects, it may be advantageous to have the feedthrough wire protrude enough to provide sufficient material for a weld pool during the welding process. As discussed, the angle 242a of the angled weld surface 242 facilitates in maintaining intimate contact between the distal portion of the feedthrough wire and the weld surface 242. The angle 242a is preferably an acute angle of less than about 45 degrees, for example between about 5 degrees and 15 degrees.

[0030] FIG. 2C is a schematic bottom-up view of the electrode assembly 240 shown in FIGs. 2A and 2B. In other words, FIG. 2C is a view of the electrode assembly 240 along main axis 260A from the proximal end. As can be seen, angled weld surface 242 has a curved surface in the form of a “V” shaped geometry that assists in alignment of the feedthrough pin (not shown), helping to guide the feedthrough pin into proper position and maintained in intimate contact with the weld surface 242 during welding. The “V” shaped geometry may also assist in guiding the feedthrough wire toward the through hole 224.

[0031] FIG. 3 A is a schematic illustration of an example installation of an electrode assembly 340 on a IMD in accordance with certain aspects of the present disclosure.Feedthrough wire 360 extends along a main axis 360A from a proximal end of the IMD to the distal end of the IMD where the electrode assembly 340 is being installed. The distal end of the IMD may include a helical attachment member 310 adjacent to the location for the electrode assembly 340. Electrode assembly 340 includes an angled weld surface 342 and optional guide surface 346 located so that when the electrode assembly 340 is installed in the presence of a feedthrough wire 360, the feedthrough wire 360 is guided onto the angled weld surface 342. By virtue of the angle of weld surface 342, a bias is formed between the weld surface 342 and the feedthrough wire 360 that maintains intimate contact between them when the electrode assembly 340 is fully installed. In other words, as the electrode 340 is pressed into the header of the IMD, the pin portion (distalend) of the feedthrough wire 360 will contact the angled weld surface 342 and deform, thereby forcing intimate contact. Upon installation, the pin portion of the feedthrough wire 360 may extend into a through hole 324 towards a chamber 322 in the distal portion of the electrode assembly 340. The chamber 322, which provides a cavity for inclusion of a drug or other treatment, may be covered with a cap 320. Cap 320 may be a sintered electrode surface, for example composed of TiN. The electrode assembly 340 may include a chamber aperture 344b for accessing the chamber 322. A corresponding aperture 344a may be included in the housing of the IMD such that when the electrode assembly 340 is fully installed, the apertures 344a and 344b are aligned. The housing of the IMD may include a lateral weld aperture 334 to facilitate access of the feedthrough wire 360 and angled weld surface 342 during a lateral weld operation to attach the feedthrough wire 360 to the angled weld surface 342.

[0032] FIG. 3B schematically illustrates a side view of a portion of the IMD shown in FIG. 3 A after installation of the electrode assembly 340. Chamber aperture 344 provides access to the chamber of the electrode assembly 340, and lateral weld aperture 334 provides access to the feedthrough wire 360 and angled weld surface 342 for performing a lateral weld operation. This allows the weld to be made in a consistent and repeatable manner without major obstructions and with the assurance that intimate contact between the feedthrough wire 360 and the weld surface 342 will be maintained during the process.

[0033] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0034] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readablemedium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media (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 that can be accessed by a computer).

[0035] 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 circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0036] All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

[0037] As used herein, the term “or” refers to an inclusive definition, for example, to mean “and / or” unless its context of usage clearly dictates otherwise. The term “and / or” refers to one or all of the listed elements or a combination of at least two of the listed elements.

[0038] As used herein, the phrases “at least one of’ and “one or more of’ followed by a list of elements refers to one or more of any of the elements listed or any combination of one or more of the elements listed.

[0039] As used herein, the terms “coupled” or “connected” refer to at least two elements being attached to each other either directly or indirectly. An indirect coupling may include one or more other elements between the at least two elements being attached. Further, in one or more embodiments, one element “on” another element may be directly or indirectly on and may include intermediate components or layers therebetween. Either term may be modified by “operatively” and “operably,” which may be used interchangeably, to describe that the coupling or connection is configured to allow the components to interact to carry out described or otherwise known functionality. For example, a controller may be operablycoupled to a resistive heating element to allow the controller to provide an electrical current to the heating element.

[0040] As used herein, any term related to position or orientation, such as “proximal,” “distal,” “end,” “outer,” “inner,” and the like, refers to a relative position and does not limit the absolute orientation of an embodiment unless its context of usage clearly dictates otherwise.

[0041] As used herein, the term “configured to” may be used interchangeably with the terms “adapted to” or “structured to” unless the content of this disclosure clearly dictates otherwise.

[0042] Th singular forms “a,” “an,” and “the” encompass embodiments having plural referents unless its context clearly dictates otherwise.

[0043] As used herein, “have,” “having,” “include,” “including,” “comprise,” “comprising” or the like are used in their open-ended sense, and generally mean “including, but not limited to.” It will be understood that “consisting essentially of,” “consisting of,” and the like are subsumed in “comprising,” and the like.

[0044] Reference to “one embodiment,” “an embodiment,” “certain embodiments,” or “some embodiments,” etc., means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout are not necessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0045] The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the disclosure.

[0046] The following examples are a non-limiting list of clauses in accordance with one or more techniques of this disclosure.

[0047] Example 1. An implantable medical device that includes a housing that extends from a proximal end to a distal end along a main axis direction, the medical device comprising: a feedthrough wire extending through the housing substantially along themain axis direction to an electrode assembly located near the distal end of the housing, the electrode assembly including a weld surface positioned to form an acute angle relative to the main axis and disposed to engage and maintain contact with the feedthrough wire, wherein the electrode assembly is configured to deliver electrical stimulation to and / or sense electrical activity from cardiac tissue when the implantable medical device is implanted.

[0048] Example 2. The implantable medical device according to Example 1, further comprising a helical fixation element extending from the distal end of housing.

[0049] Example 3. The implantable medical device according to any of the previous claims, wherein the weld surface forms an angle of less than about 30 degrees with the main axis.

[0050] Example 4. The implantable medical device according to any of the previous claims, wherein the electrode assembly further comprises a guide surface positioned proximally to the weld surface, the guide surface forming an angle relative to the main axis that is larger than the acute angle formed by the weld surface relative to the main axis.

[0051] Example 5. The implantable medical device according to any of the previous claims, wherein the weld surface has an overall curved shape when viewed along the main access.

[0052] Example 6. The implantable medical device according to claim 5, wherein the curved shape of the weld surface directs a distal end of the feedthrough wire into a through hole of the electrode assembly.

[0053] Example 7. The implantable medical device according to any of the previous claims, wherein the housing comprises a lateral weld aperture located to allow access for lateral welding of the feedthrough wire to the weld surface from a direction substantially orthogonal to the main axis.

[0054] Example 8. The implantable medical device according to any of the previous claims, wherein the electrode assembly further includes a chamber located at a distal end of the electrode assembly.

[0055] Example 9. The implantable medical device according to Example 8, wherein the chamber is configured to deliver a steroid or other treatment to cardiac tissue adjacent to the electrode assembly.

[0056] Example 10. The implantable medical device according to Examples 8 or 9, wherein the chamber is covered by a cap that forms a surface of the electrode assembly configured for contact with the cardiac tissue when the implantable medical device is implanted.

[0057] Example 11. The implantable medical device according to any of Examples 8 to 10, wherein the cap is composed of TiN.

[0058] Example 12. An electrode assembly for inclusion in an implantable medical device, the electrode assembly comprising: a weld surface configured for laterally welding thererto a distal portion of a feedthrough wire, the weld surface being oriented at an acute angle relative to a main axis defined by a direction of extension of the feedthrough wire such that positioning of the weld surface in contact with the distal portion of the feedthrough wire bends the feedthrough wire to thereby create a bias that maintains intimate contact between the weld surface and the distal portion of the feedthrough wire.

[0059] Example 13. The electrode assembly of Example 12, wherein the weld surface forms an angle of less than about 20 degrees with the main axis.

[0060] Example 14. The electrode assembly of Examples 12 or 13, further comprising a guide surface positioned proximally to the weld surface, the guide surface forming an angle relative to the main axis that is larger than the acute angle formed by the weld surface relative to the main axis.

[0061] Example 15. The electrode assembly of Examples 12 to 14, wherein the weld surface has an overall curved shape when viewed along the main access.

[0062] Example 16. The electrode assembly of Example 15, wherein the curved shape of the weld surface directs the distal end of the feedthrough wire into a through hole of the electrode assembly.

[0063] Example 17. A method for assembling an implantable medical device that includes a housing that extends from a proximal end to a distal end along a main axis direction, the method comprising: extending a feedthrough wire through the housing substantially along the main axis direction such that a distal end of the feedthrough wire terminates at a location near the distal end of the housing; installing an electrode assembly over the distal end of the feedthrough wire such that the distal end of the feedthrough wire engages with a weld surface of the electrode assembly, the weld surface forming an acuteangle relative to the main axis direction to thereby maintain intimate contact between the weld surface and the feedthrough wire; and laterally welding the feedthrough wire to the weld surface from a direction orthogonal to the main axis direction.

[0064] Example 18. The method of Example 17, wherein the step of laterally welding takes place using laser welding, resistance welding, or microtag welding.

Claims

WHAT IS CLAIMED:

1. An implantable medical device that includes a housing that extends from a proximal end to a distal end along a main axis direction, the medical device comprising:a feedthrough wire extending through the housing substantially along the main axis direction to an electrode assembly located near the distal end of the housing, the electrode assembly including a weld surface positioned to form an acute angle relative to the main axis and disposed to engage and maintain contact with the feedthrough wire, wherein the electrode assembly is configured to deliver electrical stimulation to and / or sense electrical activity from cardiac tissue when the implantable medical device is implanted.

2. The implantable medical device according to claim 1, further comprising a helical fixation element extending from the distal end of the housing.

3. The implantable medical device according to claims 1 or 2, wherein the weld surface forms an angle of less than about 30 degrees with the main axis.

4. The implantable medical device according to any of claims 1 through 3, wherein the electrode assembly further comprises a guide surface positioned proximally to the weld surface, the guide surface forming an angle relative to the main axis that is larger than the acute angle formed by the weld surface relative to the main axis.

5. The implantable medical device according to claim 1, wherein the weld surface has a curved shape when viewed along the main axis, the curved shape of the weld surface directs a distal end of the feedthrough wire into a through hole of the electrode assembly.

6. The implantable medical device according to any of claims 1 through 5, wherein the housing comprises a lateral weld aperture located to allow access for lateral welding of the feedthrough wire to the weld surface from a direction substantially orthogonal to the main axis.

7. The implantable medical device according to claims 1 through 6, wherein the electrode assembly further includes a chamber located at a distal end of the electrode assembly.

8. The implantable medical device according to claim 7, wherein the chamber is configured to deliver a steroid or other treatment to cardiac tissue adjacent to the electrode assembly.

9. The implantable medical device according to claim 7, wherein the chamber is covered by a cap that forms a surface of the electrode assembly configured for contact with the cardiac tissue when the implantable medical device is implanted.

10. The implantable medical device according to any of claim 9, wherein the cap is composed of TiN.

11. An electrode assembly for inclusion in an implantable medical device, the electrode assembly comprising:a weld surface configured for laterally welding thererto a distal portion of a feedthrough wire, the weld surface being oriented at an acute angle relative to a main axis defined by a direction of extension of the feedthrough wire such that positioning of the weld surface in contact with the distal portion of the feedthrough wire bends the feedthrough wire to thereby create a bias that maintains intimate contact between the weld surface and the distal portion of the feedthrough wire.

12. The electrode assembly of claim 11, further comprising a guide surface positioned proximally to the weld surface, the guide surface forming an angle relative to the main axis that is larger than the acute angle formed by the weld surface relative to the main axis.

13. The electrode assembly of claim 11, wherein the weld surface has an overall curved shape when viewed along the main axis, wherein the curved shape of the weld surface directs the distal end of the feedthrough wire into a through hole of the electrode assembly.

14. A method for assembling an implantable medical device that includes a housing that extends from a proximal end to a distal end along a main axis direction, the method comprising:extending a feedthrough wire through the housing substantially along the main axis direction such that a distal end of the feedthrough wire terminates at a location near the distal end of the housing;installing an electrode assembly over the distal end of the feedthrough wire such that the distal end of the feedthrough wire engages with a weld surface of the electrode assembly, the weld surface forming an acute angle relative to the main axis direction to thereby maintain intimate contact between the weld surface and the feedthrough wire; and laterally welding the feedthrough wire to the weld surface from a direction orthogonal to the main axis direction.

Images