Biostimulator feedthrough with integrated electrode cup

Abstract

A biostimulator, such as a leadless cardiac pacemaker, is described that includes an electrical feedthrough assembly mounted on a housing. An electronics compartment of the housing may contain an electronics assembly to generate pacing pulses, and the electrical feedthrough assembly may include an electrode head to deliver the pacing pulses to a target tissue. An integrally formed electrode body may have a pin integral to a cup. The pin may be electrically connected to the electronics assembly, and the cup may be electrically connected to the electrode head. Thus, the biostimulator may deliver pacing pulses to the target tissue through the integral pin and cup. The cup may contain a filler having a therapeutic agent for delivery to the target tissue, and may include a retaining element for maintaining the filler in a predetermined position within the cup. The retaining element may include a coil, a spring, or a spacer that biases the filler toward a base of the cup and away from the electrode head.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This Patent Cooperation Treaty (PCT) patent application is related to and claims priority to U.S. Provisional Patent Application No. 62 / 750,681, filed on October 25, 2018, entitled "Biostimulator Feedthrough with Integrated Electrode Cup". This application also claims priority to U.S. Provisional Patent Application No. 62 / 895,409, filed on September 3, 2019, entitled "Biostimulator Feedthrough with Integrated Electrode Cup". The contents of the above patent applications are hereby incorporated by reference in their entirety. Technical Field

[0003] The present disclosure relates to biostimulators, electrical feedthrough assemblies, and methods. More specifically, the present disclosure relates to a leadless biostimulator having an electrical feedthrough assembly (or simply "electrical feedthrough"), and more particularly to a method for manufacturing an electrical feedthrough assembly. Background Art

[0004] Cardiac pacing by an artificial pacemaker provides electrical stimulation to the heart when the heart's own natural pacemaker and / or conduction system is unable to provide synchronized atrial and ventricular contractions at a rate and interval sufficient to keep the patient healthy. This anti-bradycardia pacing has provided symptom relief and even life support for hundreds of thousands of patients. Cardiac pacing can also provide electrical overdrive stimulation to suppress or convert tachyarrhythmias, again relieving symptoms and preventing or terminating arrhythmias that could lead to sudden cardiac death.

[0005] Cardiac pacing with currently available or conventional pacemakers is typically performed by implanting a pulse generator subcutaneously or submuscularly in or near the patient's chest region. Pulse generator parameters are typically queried and modified by an external programming device, via a loosely coupled transformer having one inductance inside the body and another inductance outside, or via electromagnetic radiation having one antenna inside the body and another antenna outside. The generator is typically connected to the proximal end of one or more implanted leads, the distal end of the lead containing one or more electrodes for positioning adjacent to the inner or outer wall of the heart chamber. The lead has one or more insulated electrical conductors for connecting the pulse generator to electrodes in the heart. Such electrode leads typically have a length of 50 to 70 centimeters.

[0006] The pulse generator may have an electrical feedthrough to provide a circuit path from the interior of the airtight battery container to the external lead connection. The circuit path typically includes a conductor pin with one end inside the sealed container and the other end at the external connection.

[0007] Conventional pacemakers have several disadvantages, including the risk of lead or feedthrough pin breakage, complex connections between the leads and feedthrough pins, and the risk of infection and morbidity due to separate lead and pulse generator components. Many of the problems associated with conventional pacemakers can be addressed by developing self-contained and self-sustaining biostimulators, or so-called leadless biostimulators. Leadless biostimulators can be attached to tissue within a dynamic environment, such as within the chamber of a beating heart. However, the electrical feedthroughs used to connect the pulse generator to the leads may not include features required of a leadless biostimulator, where the pacing tip is effectively juxtaposed with the feedthrough. For example, a conventional feedthrough may not include a container for delivering a therapeutic agent at the implant site. Summary of the invention

[0008] Embodiments relate to an electrical feedthrough assembly having the features of the respective independent device claims, a biostimulator having the features of the respective other independent device claims, and a method having the features of the respective independent method claims. Furthermore, embodiments relate to another electrical feedthrough assembly having the features of the respective other independent device claims, another biostimulator having the features of the respective other independent device claims, and another method having the features of the respective other independent method claims. Features and details of the present disclosure are derived from the dependent claims, the description and the respective drawings. Therefore, features and details discussed with respect to the electrical feedthrough assembly according to the invention also relate to features and details with respect to the biostimulator and method according to the invention, and vice versa.

[0009] According to the present disclosure, an electrical feedthrough assembly for a biostimulator is provided.

[0010] The biostimulator may include an electrode body comprising a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed so that the electrode body is unitary.

[0011] According to another aspect of the present disclosure, the electrical feedthrough assembly may further include an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall, wherein the insulator base is proximal to the electrode base, wherein the insulator hole extends through the insulator base along the longitudinal axis, and wherein the pin extends from the electrode base through the insulator hole to the proximal end of the electrode body. In addition, a flange having a mounting wall may extend around the insulator wall.

[0012] In particular, a gasket of an electrical feedthrough assembly may be provided having an annular body extending around an electrode wall, wherein the gasket is distal to an insulator wall and a mounting wall, and wherein the gasket comprises a resilient material.

[0013] Advantageously, the electrical feedthrough assembly further comprises an electrode head mounted on the distal end of the electrode body, wherein the electrode head comprises a terminal aperture extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end.

[0014] It is also possible that a first diameter of the terminal hole at the distal terminal end is smaller than a second diameter of the terminal hole at the proximal terminal end.

[0015] The electrical feedthrough assembly may also include one or more seepage holes extending through one or more of the electrode wall or the electrode head along a transverse axis orthogonal to the longitudinal axis.

[0016] The electrical feedthrough assembly may further include a filler in the electrode cavity, wherein the filler includes a therapeutic agent in a silicone matrix.

[0017] The electrical feedthrough assembly may also include one or more retaining features within the electrode cavity that maintain the filler at a predetermined position within the electrode cavity.

[0018] It is also possible that the one or more retaining features include one or more protrusions extending from the electrode wall and contacting the outer surface of the filler.

[0019] It is also contemplated that the one or more protrusions include a plurality of protrusions equally spaced about the longitudinal axis.

[0020] It is contemplated that the one or more retention features include one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity.

[0021] It is also possible that the one or more retention features include a lip extending circumferentially around the interior surface of the electrode wall and into the electrode cavity.

[0022] It is also possible that the one or more retention features include a coil disposed within the electrode cavity, wherein the coil extends along the longitudinal axis and contacts an outer surface of the filler.

[0023] It is also possible that the one or more retention features include a spring disposed within the electrode cavity, wherein the spring extends along the longitudinal axis and contacts an outer surface of the filler.

[0024] Alternatively, the one or more retention features include a first retention feature and a second retention feature, the first retention feature including one or more depressions formed on the electrode wall, and the second retention feature including a coil inserted into the electrode cavity distal to the filler.

[0025] It is also possible that the one or more retaining features include three protrusions evenly distributed around the longitudinal axis.

[0026] It is also possible that the one or more retaining features include three dimples evenly distributed around the longitudinal axis.

[0027] It is also possible that the one or more retention features include a first retention feature and a second retention feature, the first retention feature being composed of three protrusions evenly distributed around the longitudinal axis, and the second retention feature comprising a coil inserted into an electrode cavity distal to the filler.

[0028] It is also possible that the one or more retention features include a first retention feature and a second retention feature, the first retention feature including three dimples evenly distributed around the longitudinal axis, and the second retention feature including a coil inserted into the electrode cavity distal to the filler.

[0029] It is contemplated that the retention feature includes a spacer disposed within the electrode cavity, wherein the spacer includes a through hole extending along the longitudinal axis.

[0030] It is contemplated that the retention feature includes a tubular spacer disposed within the electrode cavity, wherein the tubular spacer includes a through hole extending along the longitudinal axis.

[0031] Furthermore, it may be provided that the retaining feature is a first retaining feature, and the electrical feedthrough assembly further comprises a second retaining feature within the electrode cavity, which maintains the filler at a predetermined position within the electrode cavity.

[0032] It is also possible that the first retaining feature is formed integrally with the electrode wall and the second retaining feature is inserted into the electrode cavity.

[0033] It can be arranged that the first retaining feature is a plurality of protrusions extending inwardly toward the longitudinal axis, and the second retaining feature is a coil inserted into the electrode cavity distal to the filler.

[0034] It can also be arranged that the plurality of protrusions consists of three protrusions evenly distributed around the longitudinal axis.

[0035] According to another aspect of the present disclosure, a biostimulator is provided.

[0036] The biostimulator may include a housing having a longitudinal axis and containing an electronics compartment.

[0037] Additionally, the biostimulator may include an electronics assembly mounted in the electronics compartment, wherein the electronics assembly includes an electrical connector.

[0038] Furthermore, the biostimulator may include an electrical feedthrough assembly (or as described) mounted on the housing, particularly according to the present disclosure.

[0039] It is also possible that the electrical feedthrough assembly includes an electrode body, which includes a cup having an electrode wall, which extends distally from an electrode base surrounding an electrode cavity located on the longitudinal axis, and a pin, which extends proximally from the electrode base along the longitudinal axis to contact an electrical connector of the electronic device assembly, and in particular the cup and the pin are formed integrally so that the electrode body is integral.

[0040] It is possible that the electrical feedthrough assembly further comprises an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall, wherein the insulator base is proximate to the electrode base, wherein the insulator hole extends through the insulator base along the longitudinal axis, and wherein the pin extends from the electrode base through the insulator hole to the electrical connector.

[0041] It is possible that the electrical feedthrough assembly further comprises a flange mounted on the housing and having a mounting wall extending around the insulator wall.

[0042] The biostimulator may also include a screw mount mounted on the flange.

[0043] The biostimulator may further include a gasket having an annular body extending around the electrode wall, wherein the annular body is resiliently compressed between the screw mount and the mounting wall.

[0044] The biostimulator may further include a fixing element mounted on the screw mount, wherein the fixing element includes a screw that rotates about the longitudinal axis in a first rotational direction, and wherein the screw mount is mounted on the flange by a threaded connection having threads that rotate about the longitudinal axis in a second rotational direction opposite to the first rotational direction.

[0045]

[0013] It is possible that the electrical feedthrough assembly further comprises an electrode head mounted on the distal end of the electrode body, wherein the electrode head comprises a terminal aperture extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end.

[0046] It may be that a first diameter of the terminal aperture at the distal terminal end is smaller than a second diameter of the terminal aperture at the proximal terminal end.

[0047]

[0013] Optionally, the electrical feedthrough assembly further comprises a filler in the electrode cavity, wherein the filler comprises a therapeutic agent in a silicone matrix.

[0048] It is possible that the electrical feedthrough assembly further comprises a retaining feature within the electrode cavity that maintains the filler at a predetermined position within the electrode cavity.

[0049] It may be that the retaining feature comprises one or more protrusions extending from the electrode wall and contacting the outer surface of the filler.

[0050] It may be that the one or more protrusions comprise a plurality of protrusions equally spaced about the longitudinal axis.

[0051] It may be that the retaining feature comprises one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity.

[0052] It may be that the retaining feature comprises a lip extending circumferentially around the interior surface of the electrode wall and into the electrode cavity.

[0053] It is possible that the retention feature comprises a coil disposed within the electrode cavity, wherein the coil extends along the longitudinal axis and contacts an outer surface of the filler.

[0054] It is possible that the retaining feature comprises a spring disposed within the electrode cavity, wherein the spring extends along the longitudinal axis and contacts an outer surface of the filler.

[0055] It may be arranged that the retaining feature comprises a spacer disposed within the electrode cavity, wherein the spacer comprises a through hole extending along the longitudinal axis, the spacer being in contact with an outer surface of the filler.

[0056] It may be arranged that the retaining feature comprises a tubular spacer disposed within the electrode cavity, wherein the tubular spacer comprises a through hole extending along the longitudinal axis, the tubular spacer being in contact with an outer surface of the filler.

[0057] It may be arranged that the retaining feature comprises a first retaining feature and a second retaining feature within the electrode cavity, which maintain the filler at a predetermined position within the electrode cavity.

[0058] It may be provided that the first retaining feature is formed integrally with the electrode wall and the second retaining feature is inserted into the electrode cavity.

[0059] It can be arranged that the first retaining feature is a plurality of protrusions extending inwardly toward the longitudinal axis, and the second retaining feature is a coil inserted into the electrode cavity distal to the filler.

[0060] Furthermore, it can be provided that the plurality of projections consists of three projections which are evenly distributed around the longitudinal axis.

[0061] It may be provided that the plurality of protrusions comprises three protrusions evenly distributed around the longitudinal axis.

[0062] It may be arranged that the plurality of protrusions include three recesses evenly distributed around the longitudinal axis.

[0063] It is also possible that the one or more retention features include a first retention feature and a second retention feature, the first retention feature being composed of three protrusions evenly distributed around the longitudinal axis, and the second retention feature comprising a coil inserted into an electrode cavity distal to the filler.

[0064] It is also possible that the one or more retention features include a first retention feature and a second retention feature, the first retention feature including three dimples evenly distributed around the longitudinal axis, and the second retention feature including a coil inserted into the electrode cavity distal to the filler.

[0065] According to another aspect of the present disclosure, a method is provided, in particular for manufacturing an electrical feedthrough assembly or a biostimulator according to the present disclosure.

[0066] The method may include the following steps, which are performed one after another or in any order, whereby the individual steps may also be repeated: forming a distal portion of an electrode body, wherein the distal portion includes a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on the longitudinal axis; forming a proximal portion of the electrode body, wherein the proximal portion includes a pin which is integral with the cup and wherein the pin extends proximally from the electrode base along the longitudinal axis.

[0067] The method may also include inserting a pin through the insulator hole of the insulator; and bonding the pin to the insulator via a brazed joint.

[0068] The method may further include inserting an insulator into the mounting hole in the flange; and bonding the insulator to the flange via a second brazed joint.

[0069] The method may further include inserting a filler into the electrode cavity such that the filler is placed in contact with a retention feature within the electrode cavity.

[0070] It may also be provided that the retaining feature comprises one or more protrusions extending from the electrode wall, the method further comprising forming the one or more protrusions.

[0071] It may also be provided that the retaining feature comprises a circumferential lip extending around the electrode wall, the method further comprising forming the circumferential lip.

[0072] It may also be provided that the retaining feature comprises one or more tabs cut from the electrode wall, the method further comprising forming the one or more tabs and pressing the one or more tabs inwardly towards the longitudinal axis.

[0073] It may also be provided that a retaining feature of the one or more retaining features is insertable into the electrode cavity, the method further comprising inserting the retaining feature into the electrode cavity.

[0074] It may also be provided that the retaining feature is a coil disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the coil into the electrode cavity after inserting the filler.

[0075] It may also be provided that the retaining feature is a spring disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the spring into the electrode cavity after inserting the filler.

[0076] It may also be provided that the retaining feature is a spacer disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the spacer into the electrode cavity after inserting the filler.

[0077] It may also be provided that the retaining feature is a tubular spacer disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the tubular spacer into the electrode cavity after inserting the filler.

[0078] It may also be provided that the retaining feature is formed integrally with the electrode wall and extends inwardly into the electrode cavity, the method further comprising forming the retaining feature from the electrode wall.

[0079] It may also be provided that the retaining feature is insertable into the electrode cavity, the method further comprising inserting the retaining feature into the electrode cavity.

[0080] It may also be provided that the retention feature is a first retention feature, and wherein inserting the filler into the electrode cavity further comprises inserting the filler into the electrode cavity such that the filler is placed in contact with a second retention feature within the electrode cavity.

[0081] It may also be provided that the first retaining feature is formed integrally with the electrode wall, and the second retaining feature is insertable into the electrode cavity, the method further comprising: forming the first retaining feature; and inserting the second retaining feature into the electrode cavity.

[0082] The method may also include mounting an electrode head on a distal end of the electrode body, wherein the electrode head includes a terminal hole extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end, and wherein a first diameter of the terminal hole at the distal terminal end is smaller than a second diameter of the terminal hole at the proximal terminal end.

[0083] According to another aspect of the present disclosure, an electrical feedthrough assembly for a biostimulator may be provided.

[0084] The electrical feedthrough assembly may include an electrode body including an electrode wall extending distally from an electrode base surrounding an electrode lumen located on a longitudinal axis.

[0085] The electrical feedthrough assembly may also include an electrode head mounted on the distal end of the electrode body.

[0086] The electrical feedthrough assembly may also include a filler disposed within the electrode cavity.

[0087] The electrical feedthrough assembly may further include a retaining feature disposed within the electrode cavity and in contact with an outer surface of the filler such that the filler is retained within the electrode cavity at a predetermined position offset from the electrode tip.

[0088] It may also be provided that the filler comprises a therapeutic agent in a silicone matrix.

[0089] It may also be provided that the retaining feature comprises one or more protrusions extending from the electrode wall into the electrode cavity.

[0090] It may also be provided that the one or more protrusions comprise a plurality of protrusions equidistantly spaced about the longitudinal axis.

[0091] It may also be provided that the retaining feature comprises a spring having a closed end, the spring being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis.

[0092] It may also be provided that the length of the spring is from about 0.05 inches to about 0.075 inches, inclusive.

[0093] It may also be provided that the spring has a diameter of about 0.025 inches to about 0.050 inches, inclusive.

[0094] It may also be provided that the pitch of the spring is from about 0.005 inches to about 0.020 inches, inclusive.

[0095] It may also be provided that the spring is formed from a wire having a diameter of about 0.0020 inches to about 0.0040 inches, inclusive.

[0096] It can also be provided that the spring is formed from MP35N steel.

[0097] It may also be provided that the retaining feature comprises a coil having an open end, the coil being disposed within the electrode cavity distal to the filler and extending along the longitudinal axis.

[0098] It may also be provided that the length of the coil is from about 0.020 inches to about 0.040 inches, inclusive.

[0099] It may also be provided that the diameter of the coil is from about 0.020 inches to about 0.050 inches, inclusive.

[0100] It may also be provided that the pitch of the coil is from about 0.020 inches to about 0.040 inches, inclusive.

[0101] It may also be provided that the coil is formed from wire having a diameter of about 0.004 inches to about 0.010 inches, inclusive.

[0102] It can also be provided that the coil is formed from MP35N steel.

[0103] It may also be provided that the retaining feature comprises a spacer disposed within the electrode cavity distal to the filler.

[0104] It may also be provided that the retaining feature comprises a tubular spacer disposed within the electrode cavity distal to the filler. It may also be provided that the retaining feature comprises a plurality of legs extending proximally from the electrode head.

[0105] It may also be provided that each of the plurality of legs extends parallel to the longitudinal axis.

[0106] It may also be provided that each of the plurality of legs extends at an angle relative to the longitudinal axis.

[0107] It may also be provided that the retaining feature is a first retaining feature and that the electrical feed-through assembly further comprises a second retaining feature.

[0108] It can also be provided that the first retaining feature is formed integrally with the electrode wall and the second retaining feature is inserted into the electrode cavity.

[0109] It may also be provided that the first retaining feature comprises one or more protrusions extending from the electrode wall into the electrode cavity, and the second retaining feature comprises a coil having an open end, the coil being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis.

[0110] It can also be provided that the one or more protrusions consist of three protrusions evenly distributed around the longitudinal axis.

[0111] It may also be provided that the retaining feature biases the filler proximally towards the electrode base.

[0112] It may also be provided that the electrode body comprises a cup having an electrode wall and an electrode base, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed so that the electrode body is unitary.

[0113] According to another aspect of the present disclosure, a biostimulator is provided.

[0114] The biostimulator may include a housing having a longitudinal axis and containing an electronics compartment.

[0115] Additionally, the biostimulator may include an electronics assembly mounted in the electronics compartment, wherein the electronics assembly includes an electrical connector.

[0116] Furthermore, the biostimulator may include an electrical feedthrough assembly (or as described) mounted on the housing, particularly according to the present disclosure.

[0117] In addition, the electrical feedthrough assembly may include at least one of: an electrode body, which includes a cup having an electrode wall, which extends distally from an electrode base surrounding an electrode cavity located on a longitudinal axis; an electrode head, which is mounted on a distal end of the electrode body; a filler disposed in the electrode cavity; and a retaining feature, which is disposed in the electrode cavity and contacts an outer surface of the filler so that the filler is retained at a predetermined position in the electrode cavity that is offset from the electrode head.

[0118] It is possible that the filler comprises a therapeutic agent in a silicone matrix.

[0119] It is also possible that the retaining feature comprises one or more protrusions extending from the electrode wall into the electrode cavity.

[0120] It is also possible that the one or more protrusions include a plurality of protrusions equally spaced about the longitudinal axis.

[0121] It is also possible that the retention feature includes a spring having a closed end, the spring being disposed within the electrode cavity distal to the filler and extending along the longitudinal axis.

[0122] It is also possible that the retention feature includes a coil having an open end, the coil being disposed within the electrode cavity distal to the filler and extending along the longitudinal axis.

[0123] It is also possible that the retaining feature comprises a spacer, such as a tubular spacer, disposed within the electrode cavity distal to the filler.

[0124] It is also possible that the retention feature includes a plurality of legs extending proximally from the electrode tip.

[0125] It is also possible that each of the plurality of legs extends parallel to the longitudinal axis.

[0126] It is also possible that each of the plurality of legs extends at an angle relative to the longitudinal axis.

[0127] It is also possible that the retention feature is a first retention feature and the electrical feed-through assembly further comprises a second retention feature.

[0128] It is also possible that the first retaining feature is formed integrally with the electrode wall and the second retaining feature is inserted into the electrode cavity.

[0129] It is also possible that the first retention feature includes one or more protrusions extending from the electrode wall into the electrode cavity, and the second retention feature includes a coil with an open end, the coil is disposed in the electrode cavity distal to the filler and extends along the longitudinal axis.

[0130] It is also possible that the one or more protrusions consist of three protrusions evenly distributed around the longitudinal axis.

[0131] It is also possible that the retention feature biases the filler proximally.

[0132] It is also possible that the electrode body comprises a cup having an electrode wall and an electrode base, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed such that the electrode body is unitary.

[0133] According to another aspect of the present disclosure, a method is provided, in particular for manufacturing an electrical feedthrough assembly or a biostimulator according to the present disclosure, comprising at least one of the following steps, which steps may be performed one after another or in any order, wherein individual steps may also be repeated:

[0134] According to one step, the method may include obtaining an electrode body including a distal portion including an electrode wall extending distally from an electrode base surrounding an electrode lumen located on a longitudinal axis.

[0135] According to another step, the method may include inserting a filler into the electrode cavity such that an outer surface of the filler is placed in contact with a retaining feature within the electrode cavity to maintain the filler at a predetermined position within the electrode cavity.

[0136] According to another step, the method may include coupling the electrode distal tip end to the distal end of the electrode body such that a filler is contained at a predetermined location within the electrode cavity.

[0137] It may be provided that the retaining feature is integrally formed with the electrode wall and extends into the electrode cavity towards the longitudinal axis, the method further comprising forming the retaining feature.

[0138] It may be provided that the retaining feature comprises one or more protrusions, and forming the retaining feature comprises recessing an outer surface of the electrode wall.

[0139] It may be provided that the retaining feature comprises a dimple and that forming the dimple comprises punching a depression into the outer surface of the electrode wall.

[0140] It may be provided that the retaining feature comprises one or more tabs, and forming the retaining feature comprises cutting each of the one or more tabs from the electrode wall and pressing the tabs inwardly towards the longitudinal axis.

[0141] It may be provided that the retaining feature is a lip extending circumferentially around the electrode wall and forming the lip comprises recessing an outer surface of the electrode wall to form the lip.

[0142] It may be arranged that the retaining feature is insertable into the electrode cavity, the method further comprising inserting the retaining feature into the electrode cavity.

[0143] It may be provided that the retaining feature is a coil having an open end, and inserting the retaining feature into the electrode cavity comprises inserting the coil such that the coil extends along the longitudinal axis.

[0144] It may be provided that the retaining feature is a spring having a closed end, and inserting the retaining feature into the electrode cavity comprises inserting the spring such that the spring extends along the longitudinal axis.

[0145] It may be provided that the retaining feature is a spacer, and inserting the retaining feature into the electrode cavity comprises inserting the spacer such that the spacer extends along the longitudinal axis.

[0146] It may be provided that the retaining feature is a tubular spacer, and inserting the retaining feature into the electrode cavity comprises inserting the tubular spacer such that the tubular spacer extends along the longitudinal axis.

[0147] It may be arranged that the retaining feature is a first retaining feature, the method further comprising inserting a filler into the electrode cavity such that an outer surface of the filler is placed in contact with a second retaining feature within the electrode cavity.

[0148] It may be provided that the first retaining feature is integrally formed with the electrode wall and the second retaining feature is insertable into the electrode cavity, the method further comprising: forming the first retaining feature; and inserting the second retaining feature into the electrode cavity.

[0149] It may be provided that the first retaining feature comprises one or more protrusions, and forming the first retaining feature comprises recessing an outer surface of the electrode wall.

[0150] It may be provided that the second retention feature is a coil having an open end, and inserting the retention feature into the electrode cavity comprises inserting the coil such that the coil extends along the longitudinal axis.

[0151] The biostimulator according to the present invention can be particularly configured as a leadless biostimulator, such as a leadless cardiac pacemaker. The biostimulator may also include a housing having a pacing electrode. For example, the biostimulator includes each of a distal electrode and a proximal electrode disposed on or integral with the housing. The electrode can be integral with the housing or connected to the housing, for example, at a distance of less than a few centimeters from the housing. The housing may contain an energy source to provide power to the pacing electrode. The energy source can be, for example, a battery, such as a lithium monofluoride carbon (CFx) cell, or a hybrid battery, such as a combined CFx and silver vanadium oxide (SVO / CFx) hybrid chemical cell. Similarly, the energy source can be a supercapacitor. According to one embodiment, the energy source can be an energy harvesting device, such as a piezoelectric device that converts mechanical strain into current or voltage. The energy source can also be an ultrasonic transmitter that uses ultrasound technology to transfer energy from an ultrasonic subcutaneous pulse generator to a receiver electrode implanted on the endocardial wall.

[0152] The housing can have a longitudinal axis, which can be an axis of symmetry along which a plurality of other biostimulator components are disposed. For example, an electrical feedthrough assembly, particularly according to the present disclosure, can be mounted on a distal end of the housing along the longitudinal axis. Similarly, features that facilitate fixation of the biostimulator can be mounted on the electrical feedthrough assembly. For example, the biostimulator includes a helical mount mounted on the electrical feedthrough assembly about the longitudinal axis. In one embodiment, the fixation element can be mounted on the helical mount along the longitudinal axis.

[0153] The electrical feedthrough assembly can be an unfiltered assembly. More particularly, the configuration of the electrical feedthrough assembly can include an active component, such as a distal electrode, isolated from a ground component (e.g., a flange) by an insulator. The electrical feedthrough assembly for a biostimulator can include a distal electrode, which can also include an electrode body and / or an electrode head. The electrode head can be mounted on the electrode body, such as on a distal end of the electrode body.

[0154] The biostimulator, more particularly the electrical feedthrough assembly, may include a filler, such as a monolithic controlled release device (MCRD). The filler may include a therapeutic material and may be loaded into the cup. Thus, the filler may deliver a prescribed dose of a therapeutic agent, such as a corticosteroid, to a target tissue at an implantation site of the biostimulator in a patient.

[0155] According to an alternative embodiment, an electrode body of the present disclosure is provided, which includes various protrusions to retain a filler within an electrode cavity defined within the electrode body. The protrusion can be a tab that bends inward from the electrode wall toward the longitudinal axis of the electrode body. For example, the electrode wall can have a laser cut groove or slit extending around the tab. The tab can then be pressed inward to bend around the tab base. More particularly, the tab can extend from the tab base to the end of the tab. When the tab is bent inward, the end of the tab can be radially inward of the electrode wall and can therefore be placed in contact with the filler to retain the filler within the electrode cavity.

[0156] In one aspect of the present disclosure, an electrical feedthrough assembly for a biostimulator is provided. The feedthrough assembly includes an electrode body including a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis. The feedthrough assembly also includes a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed so that the electrode body is unitary.

[0157] In some embodiments, the electrical feedthrough assembly also includes an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall so that the insulator base is close to the electrode base. The insulator hole extends through the insulator base along the longitudinal axis, and the pin extends from the electrode base through the insulator hole to the proximal end of the electrode body. The feedthrough assembly also includes a flange having a mounting wall extending around the insulator wall. In such an embodiment, the electrical feedthrough assembly may also include a gasket having an annular body extending around the electrode wall, the gasket being distal to the insulator wall and the mounting wall and including an elastic material.

[0158] In other embodiments, the electrical feedthrough assembly further comprises an electrode head mounted on the distal end of the electrode body. The electrode head comprises a terminal hole extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end. In such embodiments, a first diameter of the terminal hole at the distal terminal end may be smaller than a second diameter of the terminal hole at the proximal terminal end. In other embodiments, the leakage hole may extend through one or more of the electrode wall or the electrode head along a transverse axis orthogonal to the longitudinal axis.

[0159] In other embodiments, the electrical feedthrough assembly may further include a filler in the electrode cavity, the filler including a therapeutic agent in a silicone matrix. In such an embodiment, the electrical feedthrough assembly may further include one or more retaining features in the electrode cavity, which maintain the filler at a predetermined position in the electrode cavity. The retaining feature may include one or more protrusions extending from the electrode wall and contacting the outer surface of the filler. The one or more protrusions may include a plurality of protrusions spaced equidistantly around the longitudinal axis. As another example, the retaining feature may include one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity. As yet another example, the retaining feature may include a lip extending circumferentially around the inner surface of the electrode wall and entering the electrode cavity.

[0160] The retention feature may also be disposed within the electrode cavity. For example, in one embodiment, the retention feature may include a coil disposed within the electrode cavity and extending along the longitudinal axis and in contact with the outer surface of the filler. In another example, the retention feature may include a spring disposed within the electrode cavity, extending along the longitudinal axis and in contact with the outer surface of the filler. In yet another example, the retention feature may include a spacer disposed within the electrode cavity, which may be, for example, a tubular or hexagonal spacer, the tubular spacer including a through hole extending along the longitudinal axis.

[0161] In some embodiments, the retention feature may be a first retention feature, and the electrical feed-through assembly may further include a second retention feature within the electrode cavity that retains the filler at a predetermined position within the electrode cavity. In such an embodiment, the first retention feature may be integrally formed with the electrode wall, and the second retention feature may be inserted into the electrode cavity. For example, the first retention feature may include a plurality of protrusions extending inwardly toward the longitudinal axis, and the second retention feature may be a coil inserted into the electrode cavity distal to the filler. The plurality of protrusions may be composed of three protrusions evenly distributed around the longitudinal axis.

[0162] In another aspect of the present disclosure, a biostimulator is provided. The biostimulator includes a housing having a longitudinal axis and containing an electronics compartment and an electronics assembly mounted in the electronics compartment, the electronics assembly including an electrical connector. The biostimulator also includes an electrical feedthrough assembly mounted on the housing. The electrical feedthrough assembly includes an electrode body including a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on the longitudinal axis. The electrical feedthrough assembly also includes a pin extending proximally from the electrode base along the longitudinal axis to contact an electrical connector of the electronics assembly. The cup and the pin are integrally formed so that the electrode body is unitary.

[0163] In one embodiment, the electrical feedthrough assembly further comprises an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall. The insulator base is proximate to the electrode base, and the insulator hole extends through the insulator base along the longitudinal axis. The pin extends from the electrode base through the insulator hole to the electrical connector. In such an embodiment, the electrical feedthrough assembly further comprises a flange mounted on the housing and having a mounting wall extending around the insulator wall. In such an embodiment, the biostimulator may further comprise a spiral mounting member mounted on the flange and a washer having an annular body extending around the electrode wall such that the annular body is elastically compressed between the spiral mounting member and the mounting wall. The spiral mounting member may comprise a fixing element mounted on the spiral mounting member. The fixing element may comprise a spiral rotating around the longitudinal axis in a first rotational direction, and the spiral mounting member may be mounted on the flange by a threaded connection having a thread rotating around the longitudinal axis in a second rotational direction opposite to the first rotational direction.

[0164] In another embodiment, the electrical feedthrough assembly of the biostimulator further includes an electrode head mounted on the distal end of the electrode body, the electrode head including a terminal hole extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end. In such an embodiment, a first diameter of the terminal hole at the distal terminal end can be smaller than a second diameter of the terminal hole at the proximal terminal end.

[0165] In yet another embodiment, the electrical feedthrough assembly of the biostimulator may include a filler in the electrode cavity, the filler including a therapeutic agent in a silicone matrix. In such an embodiment, the electrical feedthrough assembly may also include a retaining feature in the electrode cavity that maintains the filler at a predetermined position in the electrode cavity. In one example, the retaining feature may include one or more protrusions extending from the electrode wall and contacting the outer surface of the filler, and the one or more protrusions may include a plurality of protrusions equally spaced around the longitudinal axis. In another example, the retaining feature may include one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity. In yet another example, the retaining feature may include a lip extending circumferentially around the inner surface of the electrode wall and entering the electrode cavity. In yet another example, the retaining feature may include a coil disposed in the electrode cavity, the coil extending along the longitudinal axis and contacting the outer surface of the filler. In yet another example, the retaining feature may include a spring disposed in the electrode cavity, the spring extending along the longitudinal axis and contacting the outer surface of the filler. In another example, the retaining feature may include a tubular spacer disposed in the electrode cavity, the tubular spacer including a through hole extending along the longitudinal axis.

[0166] The retention feature may be a first retention feature, and the electrical feed-through may further include a second retention feature within the electrode cavity that maintains the filler at a predetermined position within the electrode cavity. In such an embodiment, the first retention feature may be formed integrally with the electrode wall, and the second retention feature may be inserted into the electrode cavity. For example, the first retention feature may include a plurality of protrusions extending inwardly toward the longitudinal axis (e.g., three protrusions evenly distributed around the longitudinal axis), and the second retention feature may be a coil inserted into the electrode cavity distal to the filler.

[0167] In another aspect of the present disclosure, a method is provided, comprising forming a distal portion of an electrode body and forming a proximal portion of the electrode body. The distal portion comprises a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis. The proximal portion comprises a pin integral with the cup such that the pin extends proximally from the electrode base along the longitudinal axis.

[0168] In one embodiment, the method further includes inserting a pin through an insulator hole of the insulator and joining the pin to the insulator by a brazed joint. The method may also include inserting the insulator into a mounting hole in the flange and joining the insulator to the flange by a second brazed joint. The method may also include inserting a filler into the electrode cavity such that the filler is placed in contact with a retaining feature within the electrode cavity.

[0169] In one embodiment, the retaining feature may include one or more protrusions extending from the electrode wall, and the method may further include forming the one or more protrusions. In another embodiment, the retaining feature may include a circumferential lip extending around the electrode wall, and the method may further include forming the circumferential lip. In yet another embodiment, the retaining feature may include one or more tabs cut from the electrode wall, and the method may further include forming one or more tabs and pressing the one or more tabs inward toward the longitudinal axis. In yet another embodiment, one of the one or more retaining features may be inserted into the electrode cavity, and the method may further include inserting the retaining feature into the electrode cavity. For example, the retaining feature may be a coil disposed in the electrode cavity and extending along the longitudinal axis, and the method may further include inserting the coil into the electrode cavity after inserting the filler. In another example, the retaining feature may be a spring disposed in the electrode cavity and extending along the longitudinal axis, and the method may further include inserting the spring into the electrode cavity after inserting the filler. In yet another example, the retaining feature may be a spacer disposed in the electrode cavity and extending along the longitudinal axis, and the method may further include inserting the spacer into the electrode cavity after inserting the filler.

[0170] In another embodiment, the retention feature is integrally formed with the electrode wall and extends inwardly into the electrode cavity, and the method further comprises forming the retention feature from the electrode wall. In yet another embodiment, the retention feature is insertable into the electrode cavity, and the method further comprises inserting the retention feature into the electrode cavity.

[0171] In yet another embodiment, the retention feature is a first retention feature, and inserting the filler into the electrode cavity further comprises inserting the filler into the electrode cavity so that the filler is placed in contact with a second retention feature within the electrode cavity. In such an embodiment, the first retention feature may be integrally formed with the electrode wall, and the second retention feature may be insertable into the electrode cavity. In this case, the method may further comprise forming the first retention feature and inserting the second retention feature into the electrode cavity.

[0172] In yet another embodiment, the method may further include mounting the electrode tip on the distal end of the electrode body. The electrode tip may include a terminal hole extending through the electrode tip along a longitudinal axis from the distal terminal end to the proximal terminal end, and a first diameter of the terminal hole at the distal terminal end may be smaller than a second diameter of the terminal hole at the proximal terminal end.

[0173] In another aspect of the present disclosure, an electrical feedthrough assembly for a biostimulator is provided. The electrical feedthrough assembly includes: an electrode body including an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis; an electrode head mounted on a distal end of the electrode body; a filler disposed within the electrode cavity; and a retaining feature disposed within the electrode cavity. The retaining feature contacts an outer surface of the filler such that the filler is retained within the electrode cavity at a predetermined position offset from the electrode head. The filler may include, for example, a therapeutic agent in a silicone matrix.

[0174] In one embodiment, the retaining feature comprises one or more protrusions extending from the electrode wall into the electrode cavity.For example, the one or more protrusions may comprise a plurality of protrusions equally spaced about the longitudinal axis.

[0175] In another embodiment, the retention feature includes a spring having a closed end, the spring being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis. Although the specific characteristics of the spring can vary, in at least some embodiments, the spring can have at least one of: a length of about 0.05 inches to about 0.075 inches and including end values; a diameter of about 0.025 inches to about 0.050 inches and including end values; and / or a pitch of about 0.005 inches to about 0.020 inches and including end values. The spring can also be formed of a wire having a diameter of about 0.0020 inches to about 0.0040 inches and including end values, and the wire can be formed of MP35N steel.

[0176] In another embodiment, the retention feature includes a coil having an open end, the coil being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis. Although the specific characteristics of the spring can vary, in at least some embodiments, the coil can be at least one of the following lengths: a length from about 0.020 inches to about 0.040 inches and including end values; a diameter from about 0.020 inches to about 0.050 inches and including end values; and / or a pitch from about 0.020 inches to about 0.040 inches and including end values. The coil can also be formed of a wire having a diameter of about 0.004 inches to about 0.010 inches and including end values, and the wire can be formed of MP35N steel.

[0177] In some embodiments, the spring, coil and / or spacer prevent the filler from moving out of the cup. For example, the filler may have a filler size, such as a maximum cross-sectional dimension taken transversely to the longitudinal axis, which is larger than the inner size of the spring, coil and / or spacer, such as the inner diameter of the coil or spring or the inner diameter of the through hole of the spacer. Such relative dimensions prevent the filler from passing through the inner diameter of the coil, spring and / or spacer, thereby promoting the retention of the filler in the cup. In addition, the inner size of the spring, coil or spacer can be sized to allow the maximum area of ​​the filler to be exposed to the surrounding environment through the internal space of the coil or spring. Therefore, the drug can be continuously eluted from the filler toward the target tissue through the coil, spring or spacer for reliable and predictable treatment.

[0178] In yet another embodiment, the retention feature comprises a spacer disposed within the electrode cavity distal to the filler.

[0179] In yet another embodiment, the retention feature comprises a hexagonal spacer disposed within the electrode cavity distal to the filler.

[0180] In another embodiment, the retention feature includes a plurality of legs extending proximally from the electrode head. In such an embodiment, each of the plurality of legs may extend parallel to the longitudinal axis. Alternatively, each of the plurality of legs may extend at an angle relative to the longitudinal axis.

[0181] In some embodiments, the retention feature is a first retention feature, and the electrical feedthrough assembly further comprises a second retention feature. In such embodiments, the first retention feature may be formed integrally with the electrode wall, and the second retention feature may be inserted into the electrode cavity. For example, the first retention feature may include one or more protrusions extending from the electrode wall into the electrode cavity (e.g., three protrusions evenly distributed around the longitudinal axis), and the second retention feature may include a coil having an open end, the coil being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis.

[0182] In other embodiments, the retention feature biases the filler proximally toward the electrode base and away from the electrode tip.

[0183] In other embodiments, the electrode body includes a cup having an electrode wall and an electrode base, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed such that the electrode body is unitary.

[0184] In yet another aspect of the present disclosure, a biostimulator is provided. The biostimulator includes a housing having a longitudinal axis and containing an electronic equipment compartment and an electronic equipment assembly mounted in the electronic equipment compartment, the electronic equipment assembly including an electrical connector. The biostimulator also includes an electrical feedthrough assembly mounted on the housing. The electrical feedthrough assembly includes: an electrode body including a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on the longitudinal axis; an electrode head mounted on a distal end of the electrode body; and a filler disposed in the electrode cavity. The electrical feedthrough assembly also includes a retaining feature disposed in the electrode cavity and in contact with an outer surface of the filler so that the filler is retained in a predetermined position in the electrode cavity that is offset from the electrode head.

[0185] In certain embodiments, the filler comprises a therapeutic agent in a silicone matrix.

[0186] In embodiments of the present disclosure, the retention feature may take various forms. For example, the retention feature may include one or more protrusions extending from the electrode wall into the electrode cavity. In this case, the one or more protrusions may include a plurality of protrusions equally spaced around the longitudinal axis. In another example, the retention feature may include a spring with a closed end, the spring being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis. In yet another example, the retention feature may include a coil with an open end, the coil being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis. In yet another example, the retention feature may include a tubular spacer disposed in the electrode cavity distal to the filler. In another example, the retention feature includes a plurality of legs extending proximally from the electrode head. In this case, the plurality of legs may extend parallel to the longitudinal axis or at an angle relative to the longitudinal axis.

[0187] In some embodiments, the retention feature is a first retention feature, and the electrical feedthrough assembly further comprises a second retention feature. In such embodiments, the first retention feature can be formed integrally with the electrode wall, and the second retention feature can be inserted into the electrode cavity. For example, the first retention feature can include one or more protrusions extending from the electrode wall into the electrode cavity (e.g., three protrusions evenly distributed around the longitudinal axis), and the second retention feature can include a coil with an open end, the coil being disposed in the electrode cavity distal to the filler and extending along the longitudinal axis.

[0188] In other embodiments, the retention feature biases the filler proximally.

[0189] In other embodiments, the electrode body includes a cup having an electrode wall and an electrode base, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed such that the electrode body is unitary.

[0190] In another aspect of the present disclosure, a method is provided. The method includes obtaining an electrode body including a distal portion, the distal portion including an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis. The method also includes inserting a filler into the electrode cavity so that an outer surface of the filler is placed in contact with a retaining feature within the electrode cavity to maintain the filler at a predetermined position within the electrode cavity. The method also includes coupling the electrode distal terminal end to the distal end of the electrode body so that the filler is contained at a predetermined position within the electrode cavity.

[0191] In certain embodiments, wherein the retaining feature is integrally formed with the electrode wall and extends into the electrode cavity toward the longitudinal axis, and the method further comprises forming the retaining feature. In such an embodiment, the retaining feature may include one or more protrusions, and forming the retaining feature may include recessing the outer surface of the electrode wall. In another such embodiment, the retaining feature may include one or more tabs, and forming the retaining feature may include cutting each of the one or more tabs from the electrode wall and pressing the tabs inwardly toward the longitudinal axis. In yet another such embodiment, the retaining feature may be a lip extending circumferentially around the electrode wall and forming the lip may include recessing the outer surface of the electrode wall to form the lip.

[0192] In other embodiments, the retention feature may be inserted into the electrode cavity, and the method further comprises inserting the retention feature into the electrode cavity. In one such embodiment, the retention feature may be a coil having an open end, and inserting the retention feature into the electrode cavity may comprise inserting the coil such that the coil extends along the longitudinal axis. In another such embodiment, the retention feature may be a spring having a closed end, and inserting the retention feature into the electrode cavity may comprise inserting the spring such that the spring extends along the longitudinal axis. In yet another such embodiment, the retention feature may be a tubular spacer, and inserting the retention feature into the electrode cavity may comprise inserting the tubular spacer such that the tubular spacer extends along the longitudinal axis.

[0193] In another embodiment, the retention feature is a first retention feature, and the method further includes inserting a filler into the electrode cavity so that the outer surface of the filler is placed in contact with a second retention feature within the electrode cavity. In such an embodiment, the first retention feature can be formed integrally with the electrode wall, and the second retention feature can be insertable into the electrode cavity. In this case, the method may also include forming the first retention feature and inserting the second retention feature into the electrode cavity. In one example, the first retention feature may include one or more protrusions, and forming the first retention feature may include recessing the outer surface of the electrode wall. As another example, the second retention feature may be a coil having an open end, and inserting the retention feature into the electrode cavity may include inserting the coil so that the coil extends along the longitudinal axis.

[0194] The above summary does not include an exhaustive list of all aspects of the present disclosure. It is contemplated that embodiments of the present disclosure include all systems and methods that can be practiced from all suitable combinations of the various aspects outlined above and disclosed in the detailed description below and particularly those pointed out in the claims filed with the present disclosure. Such combinations have specific advantages that are not specifically described in the above summary. BRIEF DESCRIPTION OF THE DRAWINGS

[0195] The novel features of the embodiments of the present disclosure are particularly set forth in the appended claims. A better understanding of the features and advantages of such embodiments will be obtained by reference to the following detailed description, which sets forth illustrative examples utilizing the principles of the present disclosure and the accompanying drawings, in which:

[0196] Figure 1 is a perspective view of a biostimulator according to an embodiment of the present disclosure.

[0197] Figure 2 yes Figure 1 Longitudinal cross-sectional view of the distal region of the biostimulator.

[0198] Figure 3 yes Figure 1 A perspective view of the electrical feedthrough assembly of the biostimulator.

[0199] Figure 4 yes Figure 3 An exploded longitudinal cross-sectional view of an electrical feedthrough assembly.

[0200] Figure 5 yes Figure 3 A longitudinal cross-sectional view of an electrical feedthrough assembly.

[0201] Figure 6 yes Figure 3 A perspective cross-sectional view of an electrode body of an electrical feedthrough assembly.

[0202] Figure 7 and 8 is a longitudinal cross-sectional view of an alternative electrode body that may be used in an electrical feedthrough assembly according to the present disclosure, the electrode body having various internal protrusions to retain filler.

[0203] Figure 9-11 is a longitudinal cross-sectional view of a packing disposed within various electrodes according to the present disclosure, each electrode having a corresponding elution port configuration.

[0204] Fig.12 is a longitudinal cross-sectional view of another electrical feedthrough assembly according to the present disclosure, the electrical feedthrough assembly including a filler retained on an exterior surface of an electrode body of the electrical feedthrough assembly.

[0205] Fig.13 is a longitudinal cross-sectional view of an alternative electrode according to the present disclosure and for use with a biostimulator according to the present disclosure, the electrode including a spring retaining element.

[0206] Fig.14 is a longitudinal cross-sectional view of another alternative electrode according to the present disclosure and for use with a biostimulator according to the present disclosure, the electrode including a coil holding element.

[0207] Fig.15 is a longitudinal cross-sectional view of another alternative electrode according to the present disclosure and for use with a biostimulator according to the present disclosure, the electrode including a tubular spacer retaining element.

[0208] Fig.16A is a longitudinal cross-sectional view of yet another alternative electrode according to the present disclosure and for use with a biostimulator according to the present disclosure, the electrode comprising an electrode head and a retaining element in the form of a plurality of legs extending proximally from the electrode head.

[0209] Fig. 16B yes Fig.16A Isometric view of the electrode head.

[0210] Fig.17A and 17B Side and distal views, respectively, of an alternative electrode head including proximally extending legs.

[0211] Fig.18 is a longitudinal cross-sectional view of another alternative electrode according to the present disclosure and for use with a biostimulator according to the present disclosure, the electrode including internal protrusions and a plurality of filler retention features in the form of coils. DETAILED DESCRIPTION

[0212] Embodiments of the present disclosure include a biostimulator, such as a leadless cardiac pacemaker, having an electrical feedthrough comprising an integral electrode body having an electrode pin integral with an electrode cup. The pin and cup can transmit pacing pulses from an electronic device assembly to a target tissue without passing the pacing pulses through welds, seams, etc. The biostimulator can be used to pace cardiac tissue as described below. However, the biostimulator can be used for other applications, such as deep brain stimulation. Therefore, referring to the biostimulator as a cardiac pacemaker is not restrictive.

[0213] Embodiments of the present disclosure may also include a biostimulator having an electrode with a filler disposed therein. The filler may be, for example, a monolithic controlled release device (MCRD) for delivering a therapeutic agent to an implantation site of the biostimulator. In order to facilitate fluid exchange within the electrode cavity and adequate exposure of the outer surface of the filler, the electrode may include various retention features configured to maintain the filler offset relative to one or more fluid ports of the electrode. Examples of such retention features include, but are not limited to, protrusions extending inwardly from the wall of the cavity to contact the outer surface of the filler; springs, coils, spacers, or similar components inserted into the electrode cavity; and / or proximally extending legs of a distal electrode tip component of the electrode.

[0214] Various embodiments of the present disclosure are described with reference to the accompanying drawings. However, certain embodiments may be practiced without one or more of these specific details or in combination with other known methods and configurations. In the following description, many specific details, such as specific configurations, dimensions, and processes, are set forth to provide a thorough understanding of the example embodiments. In other cases, well-known processes and manufacturing techniques are not described in particular detail to avoid making the description unclear unnecessarily. Throughout the specification, references to "an embodiment", "an embodiment", etc. mean that the specific features, structures, configurations, or characteristics described are included in at least one embodiment. Therefore, phrases "an embodiment", "an embodiment", etc. that appear throughout the specification do not necessarily refer to the same embodiment. In addition, specific features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

[0215] The use of relative terms throughout the specification may indicate relative positions or directions. For example, "distal" may indicate a first direction along the longitudinal axis of the biostimulator. Similarly, "proximal" may indicate a second direction opposite the first direction. These terms are provided to establish a relative frame of reference, however, and are not intended to limit the use or orientation of the biostimulator to the specific configurations described in the following various embodiments.

[0216] In one aspect of the present disclosure, a biostimulator is provided. The biostimulator includes an electrode body for delivering pacing pulses to target tissue. The electrode body can be integrally formed so that there are no welds, seams, grinding, etc. as remnants of the manufacturing process. For example, the electrode body can have a cup and a pin that are integrally formed with each other during processing. The integral electrode body can provide a variety of benefits, including more consistent delivery of pacing pulses, reduced likelihood of failure due to chemicals or liquids passing through the body, and an electrode surface morphology that is easier to clean and therefore less likely to introduce contaminants into the target anatomical structure.

[0217] refer to Figure 1, shows a perspective view of a biostimulator 100 according to an embodiment of the present disclosure. The biostimulator 100 can be a leadless biostimulator, such as a leadless cardiac pacemaker. The biostimulator 100 can include a housing 102 having a pacing electrode. For example, the biostimulator 100 includes each of a distal electrode 104 and a proximal electrode 106 disposed on or integral with the housing 102. The electrodes 104, 106 can be integral with the housing 102 or connected to the housing 102, for example at a distance of less than a few centimeters from the housing 102. The housing 102 can contain an energy source (not shown) to provide power to the pacing electrode. The energy source can be, for example, a battery, such as a lithium monofluoride carbon (CFx) cell, or a hybrid battery, such as a combined CFx and silver vanadium oxide (SVO / CFx) hybrid chemistry cell. Similarly, the energy source can be a supercapacitor. In an embodiment, the energy source can be an energy harvesting device, such as a piezoelectric device that converts mechanical strain into current or voltage. The energy source may also be an ultrasound transmitter that uses ultrasound technology to transfer energy from an ultrasound subcutaneous pulse generator to a receiver electrode implanted on the endocardial wall.

[0218] The housing 102 can have a longitudinal axis 108, which can be an axis of symmetry along which a plurality of other biostimulator components are disposed. For example, an electrical feedthrough assembly 110 can be mounted on a distal end of the housing 102 along the longitudinal axis 108. Similarly, features that facilitate securing the biostimulator 100 can be mounted on the electrical feedthrough assembly 110. For example, the biostimulator 100 includes a screw mount 112 mounted on the electrical feedthrough assembly 110 about the longitudinal axis 108. In one embodiment, a securing element 114 is mounted on the screw mount 112 along the longitudinal axis 108. As shown in FIG. Figure 1 As shown, the fixation element 114 can be a helical coil or a wire; however, embodiments of the present disclosure can include any suitable one or more fixation elements. The assembled components of the biostimulator 100 can provide a distal region 150 that is attached to the target tissue, for example, by engagement of the fixation element 114 with the target tissue. The distal region can deliver pacing pulses to the target tissue, for example, via the distal electrode 104 held against the target tissue.

[0219] refer to Figure 2 , provides Figure 1100 . The housing 102 can define an electronics compartment 202. More specifically, the electronics compartment 202 can be laterally surrounded by a housing wall 203 (e.g., a cylindrical wall) extending about the longitudinal axis 108. The housing wall 203 can include an electrically conductive, biocompatible, inert, and anodically safe material (e.g., titanium, 316L stainless steel, or other similar material) to laterally surround the electronics compartment 202. Similarly, the electrical feedthrough assembly 110 can surround the electronics compartment 202 distally, and the power supply container (not shown) can surround the electronics compartment 202 proximally. More specifically, the electronics feedthrough assembly 110, the housing wall 203, and the power supply container can surround a volume of the electronics compartment 202.

[0220] In one embodiment, the electronic device assembly 204 is mounted in the electronic device compartment 202. The electronic device assembly 204 may include, but is not limited to, a flexible circuit or a printed circuit board having one or more electronic device components mounted on a substrate. For example, the electronic device assembly 204 may include one or more processors, capacitors, etc. interconnected by electrical traces, through-holes, or other electrical connectors. In one embodiment, the electronic device assembly 204 includes an electrical connector 206 to connect to the electrical feedthrough assembly 110. For example, the electrical connector 206 may be a socket connector for accommodating the electrode pin 414, which is located below Figure 5 The case is further shown and described.

[0221] Still refer to Figure 2 , the screw mount 112 can be mounted on the electrical feedthrough assembly 110. For example, the electrical feedthrough assembly 110 can include a flange 208 having a mounting wall 308 and a shoulder 512 (eg, at Figure 3 and 5 102) to receive the screw mount 112. In one embodiment, the flange 208 is formed of titanium. The flange 208 can be mounted on the housing 102 and connected to the housing by a gas-tight seal, such as a weld 209 or any other similar gas-tight sealing connection. For example, a gas-tight weld 209 can be formed circumferentially around the joint between the proximal end of the flange 208 and the distal end of the housing 102. In one embodiment, the screw mount 112 is mounted on the flange 208 by a threaded connection 210. For example, the flange 208 can have an external thread 310 that matches the internal thread 220 of the screw mount 112. Therefore, the screw mount 112 can be screwed onto the mounting wall 308 of the flange 208. Alternatively, screw mount 112 may be press fit onto mounting wall 308, screw mount 112 may be bonded to mounting wall 308 via heat bonding or adhesive bonding, or screw mount 112 and electrical feedthrough assembly 110 may be joined together in another manner, such as by forging.

[0222] In one embodiment, the fixation element 114 includes a helix 212 mounted on the helical mount 112. The helix 212 can extend distally from the helical mount 112 about the longitudinal axis 108. For example, the helix 212 can rotate about the longitudinal axis 108. The helix 212 can include a helical wire formed by coiling or cutting from the wall of a length of tubing that extends in a direction of rotation about the longitudinal axis 108. For example, the helix 212 can rotate about the longitudinal axis 108 in a right-handed direction.

[0223] The helix 212 can be suitable for attaching the biostimulator 100 to tissue, such as cardiac tissue. For example, with a right-handed helical direction, the biostimulator 100 can be advanced into contact with the target tissue, and then the biostimulator 100 can be rotated in a right-handed direction to screw the helix 212 into the tissue. In one embodiment, the direction of rotation of the helix 212 is opposite to the direction of rotation of the threaded connection 210 between the mounting wall 308 of the flange 208 and the screw mount 112. For example, the external threads 310 on the mounting wall 308 of the flange 208 can be left-handed compared to the right-handed direction of the helix 212. Therefore, the threads 220, 310 of the threaded connection 210 rotate about the longitudinal axis 108 in a direction opposite to the helix 212. Thus, when the screw 212 is screwed into the target tissue, the torque transmitted from the flange 208 to the screw mount 112 will be in the same direction as the threads 220, 310 of the threaded connection 210, and therefore, the implantation torque will tend to tighten (rather than loosen) the threaded connection 210 between the electrical feedthrough assembly 110 and the fixation assembly 112 of the biostimulator 100.

[0224] The biostimulator 100 may be implanted in a body region having fluid, such as within the blood of a heart chamber, and therefore, portions of the biostimulator 100 may be sealed and / or protected from fluid intrusion, which may impair the function of the biostimulator 100. For example, portions of the electrical feedthrough assembly 110, such as the flange 208, may be coated with a protective coating to prevent the distal electrode 104 and the proximal electrode 106 from shorting. In one embodiment, the distal electrode 104 is spatially proximal to the flange 208, which may be a portion of the proximal electrode 106. Therefore, if blood is allowed to fill the gap between the distal electrode 104 and the proximal electrode 106, the electrodes 104, 106 may be electrically shorted and the pacing pulses may not properly pace the heart tissue. Therefore, a barrier may be included in the biostimulator 100 to prevent blood from filling the cavity within the biostimulator between the distal electrode 104 and the proximal electrode 106.

[0225] In one embodiment, the gasket 214 is resiliently compressed between the screw mount 112 and the mounting wall 308 of the flange 208. For example, the gasket 214 can have an annular body, such as an O-ring shape, that extends around the lateral wall of the distal electrode 104. Figure 4 and 5 In the case described above, the lateral wall can be the electrode wall 502 of the cup portion 412 of the distal electrode 104. In a specific embodiment, the gasket 214 can fill the gap between the proximal surface of the screw mount 112 and the distal side or surface of the electrical feedthrough assembly 110. For example, the gasket 214 can be on the wall of the insulator 306 (below Figure 3 The gasket 214 may be formed at least in part of an elastomeric material such as silicone and may thus be squeezed and deformed between the screw mount 112 and the electrical feedthrough assembly 110. The compressed gasket 214 may form a seal against the compressed surface to fill the gap between the distal electrode 104 and the proximal electrode 106. Thus, the gasket 214 may separate and protect the conductive surfaces of the biostimulator 100 from short circuiting.

[0226] Reference Figure 3 , showing Figure 1 and 2 1 is a perspective view of an electrical feedthrough assembly 110 of a biostimulator 100. The electrical feedthrough assembly 110 can be a multifunctional component. For example, unlike conventional pacemakers, in which the electrical feedthrough is separated from the pacing site by a lead, the distal electrode 104 of the electrical feedthrough assembly 110 of the biostimulator 100 can be in direct contact with the stimulation site. Thus, the electrical feedthrough assembly 110 can not only serve as an electrical via from the sealed package to the surrounding environment, but can also serve other functions, such as providing a housing for steroids or other fillers and direct tissue interaction, as described below.

[0227] In some embodiments, the electrical feedthrough assembly 110 can be an unfiltered assembly. More specifically, the configuration of the electrical feedthrough assembly 110 can include an active component, such as the distal electrode 104, isolated from a grounded component (e.g., the flange 208) by an insulator 306. The electrode head 304 of the electrical feedthrough assembly 110 for the biostimulator 100 can include the distal electrode 104, which can also include an electrode body 302 and / or an electrode head 304. In embodiments of the present disclosure, the electrode head 304 can be mounted on the electrode body 302, such as on a distal end of the electrode body 302, such as Figure 3 shown.

[0228] The electrical feedthrough assembly 110 can have an insulator 306 surrounding a portion of the electrode body 302. More specifically, the insulator 306 can contain the conductive electrode body 302 and separate it from the mounting wall 308 of the flange 208, which can also be conductive. The insulator 306 can be formed of alumina ceramic or other insulating material. Thus, the insulator 306 can electrically insulate the distal electrode 104 from the flange 208. As described above, the flange 208 can include threads 310, such as external threads on the outer surface of the mounting wall 308, which can form the electrical feedthrough assembly 110 and the screw mount 212 (such as Figure 2 In embodiments where the electrical feed-through assembly is bonded, press-fitted, or otherwise coupled to the screw mount 212, the threads 310 may be omitted or the flange 208 may include other surface features suitable for coupling the feed-through assembly 110 to the screw mount 212.

[0229] Figure 4 is an exploded view of the electrical feedthrough assembly 110. Figure 4 As shown, the flange 208 may include a mounting lip 402 to engage the distal end of the housing 102 (e.g., Figure 2 As shown in Figure 2 As shown and described above, a hermetic weld 209 can be formed around the mounting lip 402 to seal the electronics compartment 202 between the flange 208 and the housing 102. In one embodiment, the flange 208 includes a mounting hole 404 that extends distally from the electronics compartment 202 along the longitudinal axis 108 and through the distal surface 224 of the flange 208 to the surrounding environment when the biostimulator 100 is assembled. More specifically, the mounting hole 404 provides a passage between the electronics compartment 202 and the surrounding environment. The mounting wall 308 of the flange 208 can extend around the mounting hole 404. For example, an inner surface 422 of the mounting wall 308 can define the mounting hole 404.

[0230] In one embodiment, and if Figure 4As further shown, the insulator 306 has an insulator wall 406 extending distally from an insulator base 408. In one embodiment, the insulator wall 406 can be cylindrical, having an outer diameter and an inner diameter; however, other insulator shapes can be used in other embodiments of the present disclosure. The outer diameter of the insulator wall 406 can be sized to fit within the mounting hole 404 of the flange 208. In certain embodiments, the insulator base 408 can be a lateral wall extending on the interior of the insulator 306 orthogonal to the longitudinal axis 108. More particularly, the insulator wall 406 can be a transverse wall separating a distal cavity 424 of the insulator 306 from a proximal cavity 426 of the insulator 306, wherein the cavities 424, 426 are radially inward from the insulator wall 406. In one embodiment, the insulator hole 410 extends through the insulator base 408 along the longitudinal axis 108. Thus, when insulator 306 is mounted within mounting hole 404 of flange 208 , insulator hole 410 provides a passage between electronics compartment 202 and the surrounding environment.

[0231] In an embodiment of the present disclosure, the insulator 306 may include one or more insulator holes, each providing a feedthrough channel. The feedthrough channel may receive a corresponding pin of the electrode body 302 (such as the pin 414 discussed in further detail below). Thus, the electrical feedthrough assembly 110 may allow for multi-faceted pacing or sensing feedthroughs to increase device capabilities. For example, the feedthrough pins may provide multi-site pacing, spiral strain measurement, etc. The multi-polar feedthrough may provide activation of multiple components of the biostimulator 100, thereby facilitating alternate pacing, sensing, or communication options. Increased functionality may also be facilitated by providing multiple power and / or data feeds to the electronics compartment 202.

[0232] A feedthrough assembly 110 according to the present disclosure may include a unitary electrode body 302. For example, the unitary electrode body 302 may have a plurality of distinct portions that are integrally formed with one another. In one embodiment, the electrode body 302 includes a cup 412 and a pin 414 that are integrally formed such that the electrode body 302 is unitary, or in other words, has a unitary or one-piece construction. More specifically, the cup 412 and the pin 414 may be formed from a single blank of material, as described below, to manufacture the electrode body 302 such that the electrode body 302 does not have any seams, welds, etc. As shown in FIG. Figure 4 As shown, the pin 414 can be sized to fit through the insulator hole 410 of the insulator 306, and the cup 412 can be sized to fit within the distal cavity 424 of the insulator 306. Thus, the integral electrode body 302 provides an electrical pathway from the electronics compartment 202 proximal to the insulator base 408 to the cup 412 distal to the insulator base 408.

[0233] Cup 412 and pin 414 may be used to remove electronic device components 204 (each within the electronic device compartment 202) from the electronic device compartment 202. Figure 2 4 and 5. The electrode body 302 is formed of a 90 / 10 platinum / iridium alloy or another suitable conductive alloy.

[0234] The biostimulator 100, and in particular the electrical feedthrough assembly 110, can include a filler 416, such as a monolithic controlled release device (MCRD). The filler 416 is described in more detail below, but by way of introduction and not limitation, the filler 416 can include a therapeutic material and can be loaded into the cup 412. Thus, the filler 416 can deliver a prescribed dose of a therapeutic agent, such as a corticosteroid, to a target tissue at an implantation site of the biostimulator 100 in a patient.

[0235] After the filler 416 is loaded into the cup 412, the electrode head 304 can be installed on the electrode body 302. In one embodiment, the electrode head 304 includes a terminal hole 418 extending through the electrode head 304 along the longitudinal axis 108. The terminal hole 418 can provide a passage between the interior of the cup 412 and the surrounding environment. Therefore, the therapeutic agent eluted by the filler 416 can pass through the terminal hole 418 to the target tissue at the implantation site of the biostimulator 100. In other embodiments, the electrode head 304 and / or the electrode body 302 can include other openings or ports through which fluids can enter and exit the cup 412. The electrode head 304 can be conductive and in electrical contact with the electrode body 302 so that pacing pulses transmitted from the electronic device assembly 204 through the electrode body 302 can propagate through the electrode head 304 to the target tissue.

[0236] In certain embodiments, each component of the electrical feedthrough assembly 110 may be formed symmetrically about the longitudinal axis 108. For example, Figure 4 The cross-sectional area of ​​the electrode body 302 shown in the figure can be swept around the longitudinal axis 108 so that the pin 414 and the cup 412 have a cylindrical profile. In other embodiments, the profile of one or more components of the electrical feedthrough assembly 110 can be non-cylindrical. For example, a cross-section of the electrode body 302 taken around a transverse plane extending orthogonal to the longitudinal axis 108 can reveal the outer surface of the pin 414 and / or the cup 412, which is a square, pentagon, elliptical, etc. or any other suitable shape. Therefore, the specific shapes shown in the drawings are provided by way of example only and are not necessarily provided in a limiting manner.

[0237] Now refer to Figure 5 , provides a longitudinal cross-sectional view of the electrical feedthrough assembly 110 in an assembled state. Figure 5As shown, the cup 412 can include an electrode wall 502 extending distally from the electrode base 504. In some embodiments, the electrode wall 502 can be a cylindrical wall having an outer surface facing the surrounding environment and an inner surface facing the interior of the cup 412. The interior of the cup 412 can be an electrode cavity 506 defined between the electrode base 504 and the electrode head 304, into which the filler 416 is loaded and within which the filler 416 is delivered to the target site. The filler 416 can have an outer surface 508 facing the inner surface 520 of the electrode wall 502. Therefore, the inner surface 520 of the electrode wall 502 can extend around the electrode cavity 506 and the filler 416. As described below, the electrode body 302 can include one or more retention features on the inner surface 520 of the electrode wall 502, or otherwise be disposed within the electrode cavity 506, to retain the filler 416 at a predetermined position within the electrode cavity 506 without hindering the elution of the agent.

[0238] In one embodiment, the insulator wall 406 extends around the electrode wall 502 and / or the electrode base 504. For example, the electrode body 302 may have an outer surface 522 that is sized and shaped to fit within the distal cavity 424 of the insulator 306, and thus, the inner surface of the insulator wall 406 may face the outer surface 522 of the electrode body 302. As described above, the pin 414 of the electrode body 302 can extend proximally through the insulator hole 410. For example, the pin 414 can extend proximally from the electrode base 504 along the longitudinal axis 108 to the proximal end 510 of the electrode body 302. Thus, when the biostimulator 100 is assembled, the pin 414 can extend proximally from the electrode base 504, through the insulator hole 410, and contact the electrical connector 206 of the electronic device assembly 204 (e.g., as shown in FIG. 2 ). Figure 2 ). In this arrangement, the insulator base 408 is located proximal to the electrode base 504.

[0239] The flange 208 may include a shoulder 512 extending between the mounting wall 308 and the mounting lip 402. Figure 2 As shown, when the electrical feed-through assembly 110 is mounted on the housing 102, the shoulder 512 can define a distal portion of the electronic device compartment 202. Thus, the shoulder 512 can extend around the pin 414 of the electrode body 302. Similarly, the mounting wall 308 of the flange 208 can extend around the insulator wall 406, and the insulator 306 can have an outer surface 524 that is sized and shaped to fit within the mounting hole 404 of the flange 208.

[0240] Based on the above assembly structure, it can be understood that the various components of the electrical feedthrough assembly 110 can be assembled together during an assembly process, such as during a method of manufacturing the electrical feedthrough assembly 110. For example, in an example operation, the pin 414 can be inserted through the insulator hole 410 of the insulator 306. When the pin 414 is installed in the insulator hole 410, the proximal surface of the electrode base 504 can face the distal surface of the insulator base 408.

[0241] In a subsequent example operation, the electrode body 302 can be bonded to the insulator 306. The bond between the electrode body 302 and the insulator 306 can provide a mechanical attachment between the components, as well as a seal between the pin 414 and the insulator base 408 to prevent the fluid or energy chemical from entering or flowing out through the portion of the insulator hole 410 that is not blocked by the pin 414. Thus, the bond between the components can be a hermetic seal. For example, the pin 414 can be bonded to the insulator 306 via a brazed joint 514. The brazed joint 514 can include, but is not limited to, a gold braze that at least partially flows into the insulator hole 410 to secure and seal the pin 414.

[0242] In another subsequent example operation, the insulator 306 may be inserted into the mounting hole 404 in the flange 208 such that the insulator 306 is located at a predetermined longitudinal position within the mounting hole 404. For example, the insulator 306 may be positioned such that the distal surface of the mounting wall 308 and the distal surface of the insulator wall 406 are longitudinally juxtaposed, e.g., as Figure 5 Therefore, since the two distal surfaces 224, 526 are flush with each other, the gasket 214 ( Figure 2 512 ). The insulator 306 may be positioned such that the proximal surface of the mounting wall 308 and the proximal surface of the insulator wall 406 are longitudinally juxtaposed. For example, the proximal surface of the insulator wall 406 may be longitudinally aligned with the proximal interior surface of the shoulder 512 of the flange 208. In some embodiments, the insulator 306 may not occupy the portion of the electronic device compartment 202 that is accommodated by the shoulder 512, for example, the insulator 306 may be inserted so that the proximal surface of the insulator is flush with the distal interior surface of the shoulder 512. In this way, the space available within the electronic device compartment 202 and / or the housing can be used for electronic circuits and / or energy sources, rather than for the insulator 306. Therefore, the energy source, such as a battery, can be extended, and / or the housing 102 can be made smaller. The smaller overall footprint of the biostimulator 100 can be beneficial to device implantation and device efficacy.

[0243] In yet another operation, the insulator 306 can be bonded to the flange 208. The bond between the insulator 306 and the flange 208 can provide a mechanical attachment between the components, as well as a seal between the insulator wall 406 and the mounting wall 308 to prevent the fluid or energy chemical from entering or flowing out through the portion of the mounting hole 404 that is not blocked by the insulator 306. Thus, the bond between the components can be a hermetic seal. For example, but not limited to, the insulator 306 can be bonded to the flange 208 by a second braze joint 516. The second braze joint 516 can include a gold braze that at least partially flows into the mounting hole 404 to secure and seal the insulator 306.

[0244] In yet another example operation, one or more retention features may be formed, extended, or otherwise disposed within the electrode cavity 506 to retain the filler 416. For example, Figure 6 As shown and discussed in more detail below, at least some embodiments of the present disclosure may include a protrusion (e.g., Figure 6 ). The protrusion 612 can have a variety of suitable shapes and structures, but is generally configured to retain the filler 416 at a predetermined position within the electrode cavity 506. Therefore, in certain embodiments of the present disclosure, the operation of forming, extending, or otherwise providing one or more retaining features can include forming a protrusion. Non-limiting examples of techniques for forming the protrusion and their respective resulting structures are described below. In other embodiments (examples of which are in Figure 13-15 506 and described in further detail below), one or more retention features may additionally or alternatively include a spacer or similar component inserted into the electrode cavity 506 and configured to retain the filler 416 at a predetermined position within the electrode cavity 506. For example, but not limited to, the retention feature can be a tubular spacer, spring, or coil disposed within the electrode cavity 506. In other embodiments, the retention feature can be in the form of a leg or similar protrusion extending proximally from the electrode head 304 into the electrode cavity 506 when the electrode head 304 is assembled with the electrode body 302. An example of such an embodiment is shown in FIG. Figures 16A-17B and discussed in further detail below.

[0245] In another example operation, the filler 416 can be inserted into the electrode cavity 506. In some embodiments, the insertion of the filler 416 can be performed after the retention feature is formed, extended, or otherwise disposed within the electrode cavity 506. For example, in an embodiment including a retention feature in the form of an inwardly extending protrusion, after the protrusion is formed, the filler 416 is loaded into the electrode cavity 506, such as by pushing the filler 416 past the protrusion. By doing so, the protrusion can be placed in contact with the outer surface 508 of the filler 416, thereby retaining the filler 416 at a predetermined position within the electrode cavity 506. Alternatively, the filler 416 can be inserted into the electrode cavity 506 first, and the protrusion can be formed subsequently, such as by crimping or recessing the electrode wall 502 that defines the electrode cavity. Similarly, in embodiments in which the retaining feature is an item disposed within the electrode cavity 506 (e.g., a spring, coil, or tubular spacer), the filler 416 may be inserted into the electrode cavity 506 first, followed by the retaining feature, such that the retaining feature is located distally within the electrode cavity 506 relative to the filler 416.

[0246] In yet another example operation, the electrode tip 304 is mounted on the distal end 518 of the electrode body 302. For example, the electrode tip 304 may be placed in contact with the distal end 518 around the circumference of the distal end 518. The electrode tip 304 is then joined to the electrode body 302 by circumferential bonding. For example, an adhesive or heat weld may be formed between the distal end of the cup 412 and the electrode tip 304.

[0247] In embodiments including a retention feature in the form of a leg or protrusion extending distally from the electrode head 304 (e.g., as Figures 16A-17B 506 ), the above operations of inserting the retaining features and installing the electrode head 304 can generally be combined. For example, during assembly, the filler 416 can be inserted into the electrode cavity 506. Subsequently, the electrode head 304 can be positioned on the distal end 518 of the electrode body 302 so that the protrusion of the electrode head 304 extends into the electrode cavity 506 to retain the filler 416. Once installed, the electrode head 304 can be joined to the electrode body 302, for example, by welding, adhesives, or other similar joining methods.

[0248] Reference Figure 6, showing a perspective cross-sectional view of an electrode body 302 according to an embodiment of the present disclosure. In addition to the assembly operations described above, components of the electrical feedthrough assembly 110 may be manufactured using processes that facilitate device performance. For example, the electrode body 302 may be integrally formed from a material blank. For example, the material blank may be a cylindrical plug having an outer diameter equal to or greater than the transverse dimension of the cup 412 and a length equal to or greater than the length between the distal end 518 and the proximal end 510 of the electrode body 302. The material blank may be formed using machining, electrical discharge machining, laser cutting, grinding, or other processes to remove material and form the blank into the form of the electrode body 302. Thus, the electrode body 302 may have continuous and consistent material properties throughout the mass of the body, as compared to, for example, bonding a pin component to a separately formed cup component.

[0249] It will be appreciated that the integrally formed electrode body 302 is not only simpler and less expensive than joining multiple components, but the integrally formed electrode body 302 performs more efficiently than a multi-component electrode body. More specifically, the joint between the separate pin and cup components may not conduct pacing pulses uniformly, and / or fluid or battery chemistry may attack and pass through such joints, resulting in ineffective pacing or device failure. In contrast, the integrally formed electrode body 302 is free of welding chemistry, grinding, etc., which may leave contaminants on the electrode surface. In addition, any particulates remaining on the electrode surface from the manufacturing operation can be completely and easily cleaned, such as by using an ultrasonic bath, thereby reducing the possibility of particulates remaining in the gaps or seams of the electrode body 302. Therefore, the integrally formed electrode body 302 provides multiple benefits compared to a multi-component electrode.

[0250] In an example operation, reference Figure 6 The electrode body 302 of the electrode body 302 is formed in the distal portion of the electrode blank, for example, the cup 412 is formed by the distal portion 602 of the electrode body 302. In one embodiment of the present disclosure, forming the cup 412 includes removing material from the distal portion 602 to form an electrode cavity 506 in the electrode wall 502. The removal of material may include, but is not limited to, drilling into the material blank. The drilling operation may extend from the distal end 518 of the electrode wall 502 to the distal side 620 of the electrode base 504, so that the electrode cavity 506 may have a cavity height 604. By way of non-limiting example in at least some embodiments of the present disclosure, the cavity height 604 may be from about 0.050 inches to about 0.1 inches and includes end values, such as 0.060 or 0.079 inches. Therefore, the electrode wall 502 extends distally from the electrode base 504 around the electrode cavity 506 located on the longitudinal axis 108.

[0251] In another example operation, the pin 414 of the electrode body 302 is formed in the proximal portion of the electrode blank, for example, the pin 414 is formed from the proximal portion 606 of the electrode body 302. In one embodiment, forming the pin 414 includes removing material from the outer surface of the proximal portion 606 to form the pin 414. The removal of material may include, but is not limited to, turning down the material blank on a lathe, or grinding the outer surface to form the pin 414, so that the pin 414 has a pin diameter 608. The machining process may form the pin 414 integrally with the cup 412. Thus, the pin 414 integral with the cup 412 may extend proximally from the electrode base 504 to the proximal end 510 along the longitudinal axis 108.

[0252] Removing material to form the cup 412 and removing material to form the pin 414 may be performed in different operations. The operations may define the locations of the proximal surface 622 and the distal surface 620 of the electrode base 504, and thus may control the base thickness 610 of the electrode base 504. As a non-limiting example, the base thickness 610 may be from about 0.010 inches to about 0.05 inches, inclusive, such as 0.015 or 0.034 inches.

[0253] In certain embodiments of the present disclosure, one or more protrusions 612 are located on the inner surface 624 of the electrode wall 502. The protrusions 612 of the electrode wall 502 may extend inwardly to contact the outer surface of the filler (not shown). For example, each protrusion 612 may extend radially from the inner surface 624 to the end or end of the protrusion 612 between the electrode wall 502 and the longitudinal axis 108. In an example embodiment, the protrusion 612 may be formed integrally with the electrode wall 502. For example, each protrusion 612 may be a pit formed by embossing or recessing the outer surface 628 of the electrode wall 502.

[0254] In another example, the cup is machined as a solid part. Each protrusion 612 is then formed by punching into the electrode wall 502 from the outer surface 628 of the electrode wall 502 by recessing a depression on the electrode wall 502. By forming the recess 614 in the outer surface 628 of the electrode wall 502, the inner surface 620 of the electrode wall 502 can be deformed to a protrusion height 626 radially inward from the inner surface 624 of the rest of the cup 412. Thus, the protrusion 612 can penetrate into the cup 412 to serve as a retaining feature for the filler.

[0255] Each protrusion 612 may have a corresponding size. For example, the protrusion 612 may have a protrusion height 626 measured between the vertex 630 of the protrusion and the inner surface 624 of the electrode wall 502 surrounding the protrusion 612. In addition, the depression of the electrode wall 502 may be located at a position on the outer surface 628 of the electrode wall 502 so that the protrusion offset 616 measured between the distal side 620 of the electrode base 504 and the vertex 630 of the protrusion 612 is a predetermined distance. For example, the protrusion offset 616 can be from about 0.010 inches to about 0.050 inches and inclusive, such as 0.012 inches.

[0256] In certain embodiments of the present disclosure, a plurality of protrusions 612 may be spaced apart along the inner surface 520 of the electrode wall 502. As an example, the electrode body 302 may have two or more protrusions 612 spaced apart from each other by a separation angle 618. The plurality of protrusions 612 may be equally spaced apart around the longitudinal axis 108. For example, when the electrode body 302 has two protrusions 612, the protrusions 612 may be spaced apart around the longitudinal axis 108, and the separation angle 618 may be equal to about 180 degrees. Similarly, when the electrode body 302 has three protrusions 612, the separation angle 618 between each protrusion 612 may be equal to about 120 degrees. Alternatively, the separation angle 618 between pairs of adjacent protrusions may vary so that the protrusions 612 are not evenly distributed around the longitudinal axis 108. In certain embodiments, each protrusion 612 may have the same protrusion offset 616 so that all protrusions are distributed along a transverse plane orthogonal to the longitudinal axis 108. Alternatively, the protrusions 612 may have different protrusion offsets 616 , for example at least one of the protrusions 612 may be at a different longitudinal position than another protrusion 612 .

[0257] Reference Figure 7 , provides a longitudinal cross-sectional view of an alternative embodiment of an electrode body 700 according to the present disclosure, which includes various protrusions 612 to hold fillers (e.g. Figure 4 and 5 The filler 416) is retained in the electrode cavity 506 defined in the electrode body 700. Figure 7 , in some embodiments, the protrusion 612 can be a tab 702 that bends inwardly from the electrode wall 502 toward the longitudinal axis 108 of the electrode body 700. For example, the electrode wall 502 can have a laser cut groove or slot extending around the tab 702. The tab 702 can then be pressed inwardly to bend around the tab base 704. More specifically, the tab 702 can extend from the tab base 704 to the tab tip 706. When the tab 702 is bent inwardly, the tab tip 706 can be radially inward of the electrode wall 502 and can therefore be placed in contact with the filler to retain the filler within the electrode cavity 506.

[0258] Reference Figure 8 , provides a longitudinal cross-sectional view of another alternative embodiment of an electrode body 800 according to the present disclosure. The electrode body 800 similarly includes protrusions 612, 802 to retain a filler within an electrode cavity 506 defined by the electrode body 800, the protrusions 612, 802 extending circumferentially around the longitudinal axis 108 of the electrode body 800. For example, the electrode wall 502 can be forged along an outer surface 628 of the electrode wall 502 to form a recess 614 extending around the outer surface 628. In other words, the electrode wall 502 can be deformed radially inwardly so that the protrusion 612 is formed as a circumferential lip 802 around the electrode cavity 506. The circumferential lip 802 can be radially inward of the electrode wall 502 and can therefore be placed in contact with the filler. It will be understood that the protrusion 612, whether stamped, bent, or swaged, can share the above-mentioned descriptions of the embodiment of the present invention. Figure 6 Describes geometric features such as protrusion height, protrusion offset, or separation angle.

[0259] Reference Fig. 9 , provides Figure 1-6 4. A longitudinal cross-sectional view of an electrode 104 of FIG. As shown, the electrode 104 defines an electrode cavity 506 filled with a filler 416. The electrode 104 also includes an electrode head 304, which forms a distal end portion 902 facing the surrounding environment and opposite to the proximal end portion 904. The distal end portion 902 and the proximal end portion 904 can be on corresponding faces 910, 912 of the electrode head 304, and the faces 910, 912 can have corresponding shapes. For example, the distal side 910 can be curved or conical, and the proximal side 912 can be flat. In one embodiment, the distal side 910 of the electrode head 304 is covered with a coating (not shown) that increases the virtual surface area of ​​the electrode head 304 and controls the current density. For example, the coating can be a titanium nitride coating. As described above, the electrode head 304 can define a terminal hole 418, which extends through the electrode head 304 along the longitudinal axis 108 from the distal end portion 902 to the proximal end portion 904. The tip hole 418 may be a through hole and thus may have a first diameter 906 at the distal tip end 902 of the tip electrode 304 and a second diameter 908 at the proximal tip end 904 .

[0260] In one embodiment, the first diameter 906 of the terminal hole 418 may be smaller than the second diameter 908 of the terminal hole 418. For example, Fig. 9As shown, the terminal hole 418 may include a countersunk hole 914914 extending from the proximal terminal end 904 to an intermediate position between the distal terminal end 902 and the proximal terminal end 904. In addition, the terminal hole 418 may include a through hole 916 extending from the distal terminal end 902 to the countersunk hole 914, and the through hole 916 is narrower than the countersunk hole 914. Therefore, the portion of the terminal hole 418 corresponding to the countersunk hole 914 can increase the volume of the electrode cavity 506 to accommodate the expansion of the filler 416 or the movement / compression of the retaining element when the biostimulator is implanted in the target site. More specifically, the portion of the terminal hole 418 corresponding to the countersunk hole 914 can form a distal portion of the electrode cavity 506. Although the size of the first diameter 906 can vary, the size of the first diameter 906 is generally designed to cover and retain the filler 416 in the electrode cavity 506.

[0261] During use, the filler 416 can be located at a predetermined position in the electrode cavity 506. For example, in embodiments of the present disclosure that include a retention feature in the form of protrusions 612, the filler 416 can be radially disposed within the electrode cavity 506 between the protrusions 612 such that the protrusions 612 grip an outer surface 920 of the filler 416. In at least some embodiments, when the filler 416 is located between the protrusions 612, a proximal side 918 of the filler 416 can be adjacent to a distal side 620 of the electrode base 504.

[0262] Filler 416 may include a therapeutic agent contained within a carrier matrix. For example, the carrier matrix may be a silicone matrix, such as a monolithic silicone plug, impregnated with a therapeutic agent. The therapeutic agent may in turn be contained within the pores of the silicone matrix. In such embodiments, filler 416 may also be referred to as a monolithic controlled release device (MCRD). In at least one embodiment, the therapeutic agent may include a corticosteroid, such as dexamethasone sodium phosphate, dexamethasone acetate, and the like.

[0263] When the biostimulator is implanted at the target site, blood can flow into the electrode cavity 506 through the terminal hole 418 and cause the filler 416 to elute the therapeutic agent. The elution of the filler 416 can be controlled by its own geometry as well as the size of the electrode cavity 506 and the geometry of the electrode body 302. For example, the protrusion 612 can catch the filler 416 along the outer surface 920 without covering the entire outer surface 920. As a result, the uncovered portion of the outer surface 920 remains unobstructed by the electrode body 302 and is therefore exposed to the blood entering the electrode cavity 506. The filler 416 can be primarily held by the protrusion 612 in the cup 412 of the electrode body 302 to allow the exposed surface area of ​​the outer surface 920 to be maximized to achieve elution consistency. More specifically, the protrusion 612 can prevent the filler 416 from moving while still allowing the outer surface 920 of the filler 416 to be exposed. Therefore, the therapeutic agent can flow or leak from the uncovered portion of the outer surface 920 through the terminal hole 418 to the target tissue. Controlled dosing can reduce inflammation associated with device implantation when therapeutic agents are continuously released into the target tissue.

[0264] Fig.10 is a longitudinal cross-sectional view of an alternative electrode 1000 according to the present disclosure. As shown, the electrode 1000 includes a proximal end of an electrode body 302 and an electrode head 304, which together define an electrode cavity 506, in which a filler 416 is disposed. The filler 416 is shown to be retained in the electrode cavity 506 by one or more protrusions 612 extending inwardly from the electrode wall 502 of the electrode body 302. In contrast to the previously shown embodiments, the electrode 1000 further defines a leakage hole 1002 in the electrode head 304. Instead of or in addition to the terminal hole 418, the electrode 1000 may also include one or more leakage holes 1002. More specifically, the leakage hole 1002 may extend through one or more electrode bodies 302, such as the electrode wall 502 or the electrode head 304 of the electrode body 302. In an example embodiment, the one or more leakage holes 1002 extend through the side surface 1006 of the electrode head 304. For example, one or more leakage holes 1002 can extend along a transverse axis 1004 that is orthogonal to the longitudinal axis 108. The transverse axis 1004 can intersect the longitudinal axis 108, and the countersunk hole of the electrode head 304 and / or the through hole of the terminal hole 418 extend along the longitudinal axis 108, so the one or more leakage holes 1002 can intersect the terminal hole 418. Therefore, when the therapeutic agent is eluted from the filler 416, the agent can be delivered to the target tissue through the terminal hole 418 and / or the one or more leakage holes 1002.

[0265] Fig.111 is a longitudinal cross-sectional view of yet another electrode 1100 according to the present disclosure. Similar to the electrodes 900, 1000 discussed previously, the electrode 1100 includes an electrode body 302 and an electrode head 304, which together define an electrode cavity 506, in which a filler 416 is disposed. The filler 416 is shown as being held by one or more protrusions 612 extending inwardly from the electrode wall 502 of the electrode body 302. The electrode 1100 also defines one or more seepage holes 1002 through which blood can enter and exit the electrode cavity 506 to interact with the filler 416. As shown, the one or more seepage holes 1002 can extend through the electrode body 302, such as through the electrode wall 502. In an example embodiment, the seepage hole 1002 extends through the electrode wall 502 at the distal end 518 of the electrode body 302 to form a notch 1102 in the distal end 518. The notch 1102 in the electrode wall 502 may cooperate with a corresponding notch 1104 at the proximal terminal end 904 of the electrode head 304 to form a leak hole 1102. More particularly, the leak hole 1102 may extend through one or more of the electrode wall 502 or the electrode head 304 to intersect the electrode lumen 506. Thus, when the therapeutic agent is eluted from the filler 416, the agent may pass through the terminal hole 418 and / or the leak hole 1002 to be delivered to the target tissue.

[0266] Fig.12 is a longitudinal cross-sectional view of an electrode assembly 1200 according to the present disclosure. Fig.10 and 11 on the contrary, Fig.12 The electrode assembly 1200 includes a filler 416 retained on the outer surface 1208 of the electrode body 302. In such an embodiment, the electrode body 302 can be solid. The electrode body 302 can include a pin 414 that extends proximally through the insulator hole 410 as described above. However, the electrode body 302 may not include, for example Figure 4 Thus, in embodiments including a solid electrode body 302, there may be no electrode cavity defined within the electrode body 302, and thus, the filler 416 may instead be retained on the outer surface 1208 of the electrode body 302 rather than within an internal electrode cavity.

[0267] In one embodiment, the electrode body 302 includes a body end 1202 connected to a body core 1204 by a body neck 1206. The outer diameter of the body neck 1206 can be smaller than the outer diameter of the body end 1202 and / or the body core 1204. The filler 416 can have a geometry that fits around one or more electrode body portions to be retained on the electrode body 302. For example, the filler 416 can fit within the gap 1212 between the body end 1202 and the body core 1204. Thus, the filler 416 can include a through hole 1214, whose diameter is larger than the diameter of the body neck 1206 and / or smaller than the diameter of the body end 1202. In an example embodiment, the filler 416 can be elastically stretched on the body end 1202 so that the portion of the filler 416 located between the body end 1202 and the body core 1204 retains the filler 416 on the electrode body 302. When the biostimulator is implanted at the target site, the therapeutic agent can be eluted from the filler 416 directly into the tissue, rather than through the elution port.

[0268] As previously in Figure 6-8 As discussed in the context of, a biostimulator according to the present disclosure may include an electrode having an electrode body defining an inner electrode cavity. In certain embodiments, a filler, such as an integral controlled release device (MCRD), may be disposed within the cavity, for example to provide controlled release of a therapeutic agent at an implantation site of the biostimulator. Certain electrodes according to the present disclosure may include a retention feature configured to retain a filler at a predetermined position within the electrode cavity. Although the particular position of the filler within the electrode cavity may vary, typically, the predetermined position within the electrode cavity causes the filler to be offset from the distal terminal end. Offsetting the filler has multiple advantages. For example, offsetting the filler promotes fluid exchange within the electrode cavity, such as by preventing the filler from blocking the terminal pores or seepage holes of the electrode, thereby allowing fluid to easily flow into and out of the electrode cavity. Offsetting the filler can further ensure that a sufficient portion of the outer surface of the filler remains exposed for proper elution.

[0269] In the previously discussed embodiments, the retention feature is typically in the form of an integrally formed protrusion or tab extending inwardly from the inner wall of the electrode body into the electrode cavity. The protrusions are positioned and distributed within the electrode cavity so that when the filler is disposed within the electrode cavity, the protrusions abut the outer surface of the filler, thereby retaining the filler. In contrast to such protrusions, other embodiments of the present disclosure may include retention features in the form of insertable retaining elements that can be inserted into the electrode cavity after filling the filler. Similar to the previously discussed protrusions, the insertable retaining element is typically configured to retain the filler at a predetermined position within the electrode cavity, thereby preventing the filler from obstructing fluid exchange within the electrode cavity and ensuring that the filler is properly exposed for elution, etc. In certain embodiments, the insertable retaining element biases the filler proximally toward the electrode base. Such an insertable retaining element may be used in place of or in combination with the various integrally formed retention features discussed above.

[0270] In certain embodiments, one or more retaining elements advantageously increase free space to the interior of the feedthrough assembly to accommodate expansion of the filler. For example, one or more retaining elements can increase the free space of the electrode cavity (by minimizing the amount of volume used by the one or more retaining elements), thereby improving fluid exchange and increasing space within the electrode cavity for filler to flow in.

[0271] Fig.13 1 is a longitudinal cross-sectional view of an example electrode 1300 according to the present disclosure, including a first example retaining element in the form of a spring 1350. The electrode 1300 may be, for example, Figure 1 The electrode 1300 includes an electrode body 1302 and an electrode head 1304 coupled to the electrode body 1302. The electrode body 1302 may also include an integrally formed cup 1306 and a pin 1308, such that the electrode body 1302 is unitary. The cup 1306 may include an electrode wall 1310 extending distally from an electrode base 1312, such that the cup 1306 defines an electrode cavity 1314. A filler 1316 (e.g., a monolithic controlled release device (MCRD) containing a therapeutic agent) may be disposed within the electrode cavity 1314. After implantation of a biostimulator including the electrode 1300, a fluid may be released through a terminal hole 1318 (and / or, for example, a monolithic controlled release device (MCRD)) defined by the electrode head 1304. Fig.10 and 11 The invention also provides a method for providing a therapeutic agent for implantation in a controlled manner. The method further provides a method for providing a therapeutic agent for implantation in a controlled manner.

[0272] As previously discussed, the filler 1316 can be maintained at a predetermined position within the electrode cavity 1314 so as to, among other things, prevent the filler 1316 from migrating within the electrode cavity 1314 to block the terminal hole 1318 (or leakage hole, as in, for example, Fig.10 and 11 1316) to ensure that the outer surface 1322 of the filler 1316 remains fully exposed for proper elution and / or for other similar purposes. To achieve this retention, the electrode 1300 includes a spring 1350 disposed within the electrode cavity 1314 and extending along the longitudinal axis 1324 of the electrode 1300. The spring 1350 generally extends between the inner proximal surface 1320 of the electrode head 1304 and the distal surface 1322 of the filler 1316. It is noteworthy that when the filler 1316 reacts to body fluids, the spring 1350 is compressed in response to the expansion of the filler 1316 in the electrode cavity 1304, and the spring 1350 biases the filler 1316 in the proximal direction and can provide an increased proximal bias. In at least some embodiments, as the filler 1316 expands in response to contact with body fluids, the filler 1316 can expand into the internal volume defined by the spring 1350 and / or expand into the gap between adjacent turns of the spring 1350.

[0273] In certain embodiments of the present disclosure, spring 1350 is a closed end coil spring. Fig.13 As shown, spring 1350 includes opposing closed ends 1352, 1354. In certain embodiments, the use of a closed end spring may have certain advantages over other retention features. For example, but not limited to, the closed end 1352 of the closed end spring may generally provide a relatively high contact area and flush contact with a corresponding surface within the electrode cavity 1314 (e.g., the proximal side of the electrode head 1304). Fig.13 As shown, the closed end 1354 can also be configured to have a relatively high and substantially flush contact with the filler 1316, thereby resulting in a relatively uniform distribution of the force applied by the spring 1350 on the filler 1316. Notably, the open structure of the spring 1350 still allows the filler 1316 to expand into the spring 1350 when the filler 1316 is exposed to the fluid. However, more generally, the spring 1350 is designed to fit and be retained within the electrode cavity 1314 and interact with various surfaces of the electrode cavity 1314 so that the spring 1350 is sufficiently supported to bias or maintain the filler 1316 in a predetermined position within the electrode cavity 1314 throughout the expansion process of the filler 1316.

[0274] Although the size and characteristics of the spring 1350 can vary based on the size of the electrode cavity 1314 and the filler 1316, etc., in at least some embodiments, the length of the spring 1350 can be from about 0.05 inches to about 0.075 inches and inclusive, such as 0.063 inches, and the diameter can be from about 0.025 inches to about 0.050 inches and inclusive, such as 0.036 inches. The spring 1350 can also have a pitch from about 0.005 inches to about 0.020 inches and inclusive, such as about 0.010 inches. More generally, the length of the spring 1350 is sufficient to maintain the filler 1316 at a minimum offset relative to the electrode head 1304, and its diameter is such that the filler 1316 cannot pass through the spring 1350. Spring 1350 can be formed from a variety of wires; however, in at least some embodiments, spring 1350 is formed from a wire having a diameter from about 0.0020 inches to about 0.0040 inches and including end values ​​(e.g., 0.0030 inches). Spring 1350 is also preferably formed from a biocompatible material, such as MP35N steel, or is otherwise coated / treated to be biocompatible. In some embodiments, the material and geometry of spring 1350 are such that spring 1350 provides sufficient load to filler 1316 to keep filler 1316 positioned proximally in cup 1306, but a light enough load to allow filler 1316 to expand in a controlled manner when fluid enters the matrix. In some embodiments, the geometry and elasticity of spring 1350 configure spring 1350 to compress without breaking.

[0275] In certain embodiments, the filler 1316 may be held solely by the spring 1350, which allows the exposed surface area of ​​the filler 1316 to be maximized for elution consistency.

[0276] In certain embodiments, the filler 1316 may be retained by a combination of the protrusions 612 in the cup 1306 of the electrode body 1302 and the spring 1350, which allows the exposed surface area of ​​the filler 1316 to be maximized for elution consistency.

[0277] Controlled dosing can reduce inflammation associated with device implantation when therapeutic agents are continuously released into the target tissue.

[0278] In some embodiments, the diameter of the distal surface 1322 of the filler 1316 matches or is slightly larger than the outer diameter of the spring 1350. The filler 1316 can taper to a large enough diameter so that it will naturally center within the cup 1306 and engage all of the protrusions 612 in the cup 1306. In some embodiments, the volume of the filler 1316 within the cup 1306 is small enough to provide sufficient free volume within the electrode cavity 1314 to allow fluid to freely exchange and the filler 1316 to swell during use. As the filler 1316 expands, it can also expand into the internal volume defined by the spring 1350 and / or the gaps between adjacent turns of the spring 1350.

[0279] Fig.14 is a longitudinal cross-sectional view of an example electrode 1400 according to the present disclosure, including a second example retaining element in the form of a coil 1450, which may be, for example, Figure 1 The electrode 1400 is implemented in the feedthrough assembly 110 of the biostimulator 100. More specifically, the electrode 1400 includes an electrode body 1402 and an electrode head 1404 coupled to the electrode body 1402. The electrode body 1402 may also include a cup 1406 and a pin 1408, which are integrally formed so that the electrode body 1402 is unitary. The cup 1406 may include an electrode wall 1410 extending distally from the electrode base 1412, so that the cup 1406 defines an electrode cavity 1414, in which a filler 1416 may be disposed.

[0280] Coil 1450 holds filler 1416 at a predetermined position within electrode cavity 1414, thereby preventing filler 1416 from migrating within electrode cavity 1414 and blocking terminal hole 1418 (or leakage hole, as in, for example, Fig.10 and 11 ), to ensure that the outer surface of the filler 1416 remains fully exposed for proper elution and / or for other similar purposes. As shown, the coil 1450 is disposed in the electrode cavity 1414 so that it extends along the longitudinal axis 1424 of the electrode 1400. For example, the coil 1450 may generally extend between the inner proximal surface 1420 of the electrode head 1404 and the distal surface 1422 of the filler 1416. Similar to the spring 1350 discussed above, the coil 1450 biases the filler 1416 in the proximal direction and provides an increased proximal bias when the filler 1416 expands in the electrode cavity 1414 as the coil 1450 is compressed. When the filler 1416 expands, it may also expand into the gap between the internal volume defined by the coil 1450 and / or the adjacent turns of the coil 1450.

[0281] Coil 1450 may be an open end coil. Fig.14As shown, the coil 1450 includes opposing terminal ends 1452, 1454. In certain embodiments, the use of an open-ended coil may have certain advantages over other retention features. For example, but not limited to, an open-ended coil may generally occupy a smaller volume of the electrode cavity 1414 than other retention features. In certain embodiments, the terminal end 1454 may also be configured to impact or otherwise interfere with the filler 1416 as the filler 1416 expands, thereby improving the retention of the filler 1416 within the electrode cavity 1414. However, more generally, the coil 1450 is designed to fit and be retained within the electrode cavity 1414 and interact with various surfaces of the electrode cavity 1414 so that even as the filler 1416 expands, the coil 1450 is sufficiently supported to bias or otherwise maintain the filler 1416 within a predetermined position within the electrode cavity 1414.

[0282] Although the size and characteristics of the coil 1450 can vary, in at least some embodiments, the length of the coil 1450 can be from about 0.020 inches to about 0.040 inches and inclusive, such as 0.030 inches, and the diameter can be from about 0.020 inches to about 0.050 inches and inclusive, such as 0.035 inches. The pitch of the coil 1450 can also be from about 0.020 inches to about 0.040 inches and inclusive, such as about 0.030 inches. More generally, the length of the coil 1450 is sufficient to maintain the filler 1416 at a minimum offset relative to the electrode head 1404 and the diameter is such that the filler 1416 cannot pass through the coil 1450. The coil 1450 can be formed from a variety of wires; however, in at least some embodiments, the coil 1450 is formed from a wire having a diameter of about 0.004 inches to about 0.010 inches and inclusive (e.g., 0.007 inches). The coil 1450 is also preferably formed from a biocompatible material, such as MP35N steel, or is otherwise coated / treated to be biocompatible.

[0283] Fig.15 is a longitudinal cross-sectional view of an example electrode 1500 according to the present disclosure, which includes a third example retaining element in the form of a spacer 1550 extending along a longitudinal axis 1524, which may be, for example, Figure 1 The electrode 1500 is implemented in the feedthrough assembly 110 of the biostimulator 100. More specifically, the electrode 1500 includes an electrode body 1502 and an electrode head 1504 coupled to the electrode body 1502. The electrode body 1502 may also include a cup 1506 and a pin 1508, which are integrally formed so that the electrode body 1502 is unitary. The cup 1506 may include an electrode wall 1510 extending distally from an electrode base 1512, so that the cup 1506 defines an electrode cavity 1514, in which a filler 1516 may be disposed.

[0284] To maintain the filler 1516 within the electrode cavity 1514, the electrode 1500 includes a spacer 1550 disposed within the electrode cavity 1514 distal to the filler 1516. In some embodiments, the spacer 1550 is a tubular spacer. In some embodiments, the spacer 1550 can be another shape, such as a hexagon. The spacer 1550 generally includes a spacer body 1552 defining a through hole 1554 through which a fluid can pass to reach the filler 1516. In some embodiments, the spacer body 1550 is a tubular body. Fig.15 As shown, the spacer 1550 can be disposed between the electrode head 1504 and the filler 1516. In certain embodiments, the spacer 1550 can be free floating within the electrode cavity 1514. Alternatively, the spacer 1550 can be press-fit, adhered, or otherwise secured within the electrode cavity 1514, such as to the interior surface of the electrode wall 1510.

[0285] Although the size and characteristics of the spacer 1550 can vary based on the size of the electrode cavity 1514 and the filler 1516, etc., in at least some embodiments, the spacer 1550 can be a tubular spacer having a length of about 0.020 inches to about 0.040 inches and inclusive, such as 0.030 inches, an inner diameter of about 0.010 inches to about 0.040 inches and inclusive, such as 0.025 inches, a wall thickness of about 0.003 inches to about 0.010 inches and inclusive, such as 0.008 inches, and an outer diameter of about 0.020 inches to about 0.050 inches and inclusive, such as 0.035 inches. More generally, the length of the spacer 1550 is sufficient to maintain the filler 1516 at a minimum offset relative to the electrode head 1504, and the inner diameter is such that the filler 1516 cannot pass through the through hole 1554. Spacer 1550 can be formed from a variety of biocompatible materials; however, in at least some embodiments, spacer 1550 is formed from MP35N steel or is otherwise coated / treated to be biocompatible. In other embodiments, spacer 1550 can be formed using an elastomeric material so that it provides similar Fig.13 and 14 The bias of the spring 1350 and the coil 1450. Moreover, in order to promote fluid exchange with the filler 1516, the spacer 1550 may include a groove, channel or similar fluid path (not shown) extending longitudinally along the spacer body 1552.

[0286] In certain embodiments, the filler 1516 may be held solely by the spacer 1550, which allows the exposed surface area of ​​the filler 1516 to be maximized for elution consistency.

[0287] In some embodiments, filler 1516 can be held by a combination of protrusions 612 and spacers 1550 in cup 1506 of electrode body 1502, which allows for maximization of exposed surface area of ​​filler 1516 for elution consistency. Controlling dosage can reduce inflammation associated with device implantation when therapeutic agent is continuously released into target tissue.

[0288] In certain embodiments, the proximal diameter of the spacer 1550 is small enough to provide free space for the filler 1516 to swell, but large enough to hold the filler 1516 in place at all times.

[0289] Fig.16A 1 is a longitudinal cross-sectional view of yet another example electrode 1600 according to the present disclosure, which includes a fourth retaining element extending proximally from an electrode head 1604 in the form of a leg 1650. More specifically, the electrode 1600 includes an electrode body 1602 and an electrode head 1604 coupled to the electrode body 1602. The electrode body 1602 may also include a cup 1606 and a pin 1608, which are integrally formed so that the electrode body 1602 is unitary. The cup 1606 may include an electrode wall 1610 extending distally from an electrode base 1612, such that the cup 1606 defines an electrode cavity 1614, in which a filler 1616 may be disposed. Fig. 16B An isometric view of the electrode head 1604 is provided.

[0290] In contrast to the previously discussed retention elements, each of which is a separate component inserted into the electrode cavity 1614, the retention element of the electrode 1600 includes a plurality of legs 1650 extending proximally from the electrode head 1604 into the electrode cavity 1614. Thus, when the electrode head 1604 is coupled to the electrode body 1602 after the filler 1616 is inserted into the electrode cavity 1614, the legs 1650 extend into the electrode cavity 1614 to prevent the filler 1616 from moving or migrating distally.

[0291] As shown, the electrode head 1604 may include four legs 1650 evenly distributed around the longitudinal axis 1624. However, in other embodiments, the electrode head 1604 may include any suitable number of legs that may be evenly or unevenly distributed around the circumference of the electrode head 1604. In embodiments including multiple legs, the gaps (e.g., Fig. 16B The gap 1652 shown in FIG. 16A can facilitate improved fluid exchange with the filler 1616 .

[0292] In some embodiments, filler 1616 can be held by a combination of protrusions 612 and legs 1650 in cup 1606 of electrode body 1602, which allows for maximization of exposed surface area of ​​filler 1616 for elution consistency. Controlling dosage can reduce inflammation associated with device implantation when therapeutic agent is continuously released into target tissue.

[0293] Fig.17A and 17B 1704 are side and distal views of another electrode head 1704 that may be implemented in an electrode according to the present disclosure. Fig.16A and 16B The electrode head 1604 includes a plurality of proximally extending legs 1750 such that when assembled to the electrode body, the legs 1750 extend into an electrode cavity defined by the electrode body. Fig.16A and 16B In contrast to the legs 1650 of the electrode head 1604, the legs 1750 extend at an angle relative to the longitudinal axis 1724 of the electrode head 1704. By doing so, the contact area of ​​the outer surface of the filler obstructed by the legs 1750 is minimized, thereby improving the contact between the filler and the fluid entering the electrode cavity.

[0294] Although shown separately in the foregoing embodiments, any of the retention features discussed herein may also be used in combination. Fig.18 is a longitudinal cross-sectional view of another example electrode 1800 according to the present disclosure, which includes multiple retention features and can be, for example, in Figure 1 1800 is implemented in the feedthrough assembly 110 of the biostimulator 100. More specifically, the electrode 1800 includes an electrode body 1802 and an electrode head 1804 coupled to the electrode body 1802. The electrode body 1802 also includes a cup 1806 and a pin 1808, which in some embodiments can be integrally formed so that the electrode body 1802 is unitary. The cup 1806 includes an electrode wall 1810 extending distally from an electrode base 1812, so that the cup 1806 defines an electrode cavity 1814, in which a filler 1816 is disposed.

[0295] To retain the filler 1816 within the electrode cavity 1814, the electrode 1800 includes each protrusion (e.g., protrusion 612) formed in the electrode wall 1810 and a coil 1870 disposed within the electrode cavity 1814 distal to the filler 1816. In a particular embodiment, the electrode 1800 may include three protrusions equally spaced about the longitudinal axis 1824 of the electrode 1800 (e.g., with about 120 degrees of spacing between the protrusions), each of which may be generally spaced apart from the longitudinal axis 1824 of the electrode 1800. Figure 6 The size and dimensions of the protrusion 612 described above are consistent with the above. Similarly, the coil 1870 can generally conform to the Fig.14The case of coil 1450 discussed above.

[0296] In some embodiments, the filler 1816 may be held solely by the coil 1870, which allows the exposed surface area of ​​the filler 1316 to be maximized for elution consistency, ie, the cup 1806 has no protrusions.

[0297] It should be understood that the example electrode 1800 combining a protrusion with a coil should be considered non-limiting. More generally, any suitable combination of retaining features can be used in embodiments of the present disclosure. For example, but not limited to, any insertable retaining element discussed above (e.g., a spring, a coil, a tubular spacer, etc.) can be used in combination with any retaining feature (e.g., a protrusion, a tab, an internal lip, etc.) formed integrally with the electrode wall. In addition, more than one insertable retaining element discussed above (e.g., a spring, a coil, a tubular spacer, etc.) can be used in combination with each other and / or with more than one retaining feature (e.g., a protrusion, a tab, an internal lip, etc.) formed integrally with the electrode wall. For example, but not limited to, a spring or a coil can be surrounded by a tubular spacer and used in combination with a protrusion and / or an internal lip. In some embodiments, only one retaining element is used.

[0298] The foregoing description generally discusses retention features suitable for retaining a filler at a predetermined position within an electrode cavity. For example, such retention features are described as being integrally formed with an electrode wall defining a cavity (e.g., in the form of one or more protrusions extending into the electrode cavity) or as an element inserted into the electrode cavity distal to the filler. It should also be understood that the filler itself may include features configured to improve retention of the filler within the electrode cavity. For example, but not limited to, the filler may have a shape suitable for forming a press fit between the electrode cavity and the filler. The filler may also include external protrusions, textures, external rings / bands of relatively high friction materials, or similar external structures suitable for engaging or providing increased friction between the filler and the electrode wall. In yet another example, the filler may be configured to expand in a controlled manner (e.g., primarily in a radial direction outward from the longitudinal axis of the electrode cavity) when the therapeutic agent is eluted from the filler, thereby increasing the engagement between the filler and the electrode wall when the filler expands.

[0299] In embodiments of the present disclosure that include electrodes with multiple retention features, operations associated with the manufacture or assembly of the electrodes may be modified to account for the particular combination of retention features implemented. Fig.18In the embodiment of the electrode 1800, a first operation may include forming the electrode body 1802 by forming the cup 1806 and the pin 1808 (which may include forming the cup 1806 and the pin 1808 so that the electrode body 1802 is integral). Subsequent operations may include forming the protrusion 612 into the electrode wall 1810 (e.g., by recessing, forging, or the outer surface of the electrode wall 1810), and inserting the filler 1816 into the electrode cavity 1814 so that the filler 1816 contacts the electrode cavity 1814. The coil 1870 may then be inserted into the electrode cavity 1814 distal to the filler 1816 so that the coil 1870 contacts the filler 1816. The electrode 1800 may then be capped by inserting the electrode head 1804 and connecting the electrode head 1804 to the electrode body 1802, thereby sealing the electrode cavity 1814 with the filler 1816 and the coil 1870 contained therein.

[0300] The foregoing operations based on an example electrode including retention features in the form of protrusions and coils are intended as non-limiting examples. It should be understood that the operations may be modified (eg, by changing the order of the operations) to accommodate any combination of retention features discussed herein.

[0301] In the foregoing description, various aspects of the present disclosure have been described with reference to specific exemplary embodiments of the present disclosure. It will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the present disclosure. Therefore, the description and drawings should be regarded as illustrative rather than restrictive.

[0302] Reference signs should not be construed as limiting the scope of what is protected by the claims; their sole function is to make the claims easier to understand.

Claims

1. An electrical feedthrough assembly for an implantable leadless biostimulator, the biostimulator being configured to be implanted at a target site in a patient, the electrical feedthrough assembly comprising: An electrode body comprising a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis, and a pin extending proximally from the electrode base along the longitudinal axis, wherein the cup and the pin are integrally formed from a single blank of material so that the electrode body is unitary.

2. The electrical feedthrough assembly of claim 1 , further comprising an electrode head mounted on a distal end of the electrode body, wherein The electrode tip includes a terminal aperture extending through the electrode tip along a longitudinal axis from a distal terminal end to a proximal terminal end.

3. The electrical feedthrough assembly of claim 2, wherein: A first diameter of the terminal aperture at the distal terminal end is smaller than a second diameter of the terminal aperture at the proximal terminal end.

4. The electrical feedthrough assembly of claim 1, further comprising: a filler in the electrode cavity, wherein the filler comprises a therapeutic agent in a silicone matrix; and One or more retaining features within the electrode cavity that maintain the filler at a predetermined position within the electrode cavity.

5. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features bias the filler toward the electrode base.

6. The electrical feedthrough assembly of claim 4, wherein: The one or more retaining features include one or more protrusions on the electrode wall and in contact with an outer surface of the filler.

7. The electrical feedthrough assembly of claim 4, wherein: The one or more protrusions include a plurality of protrusions equally spaced about the longitudinal axis.

8. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity.

9. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include a lip extending circumferentially around an interior surface of the electrode wall and into the electrode cavity.

10. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include a coil disposed within the electrode cavity, wherein the coil extends along a longitudinal axis and contacts an outer surface of the filler.

11. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include a spring disposed within the electrode cavity, wherein the spring extends along the longitudinal axis and contacts an outer surface of the filler.

12. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include a tubular spacer disposed within the electrode cavity, wherein the tubular spacer includes a through hole extending along a longitudinal axis.

13. The electrical feedthrough assembly of claim 4, wherein: The one or more retention features include a first retention feature and a second retention feature within the electrode cavity that maintains a filler at a predetermined position within the electrode cavity.

14. The electrical feedthrough assembly of claim 13, wherein: The first retention feature is integrally formed with the electrode wall, and the second retention feature is inserted into the electrode cavity.

15. The electrical feedthrough assembly of claim 14, wherein: The first retention feature is one or more dimples formed in the electrode wall, and the second retention feature is a coil inserted into the electrode cavity distal to the filler.

16. The electrical feedthrough assembly of claim 14, wherein: The first retention feature consists of three protrusions evenly distributed around the longitudinal axis, and the second retention feature is a coil inserted into the electrode cavity distal to the filler.

17. The electrical feedthrough assembly of claim 2, further comprising: an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall, wherein the insulator base is proximate to the electrode base, wherein an insulator bore extends through the insulator base along a longitudinal axis, and wherein the pin extends from the electrode base through the insulator bore to a proximal end of the electrode body; and A flange has a mounting wall extending around the insulator wall.

18. The electrical feedthrough assembly of claim 17, further comprising a gasket having an annular body extending around the electrode wall, wherein: The gasket is distal to the insulator wall and the mounting wall, and wherein the gasket comprises an elastomeric material.

19. The electrical feedthrough assembly of claim 17 or 18, further comprising one or more seepage holes extending through one or more of the electrode wall or the electrode head along a transverse axis orthogonal to the longitudinal axis.

20. A biostimulator, comprising: a housing having a longitudinal axis and containing an electronics compartment; an electronic equipment assembly mounted in the electronic equipment compartment, wherein the electronic equipment assembly includes an electrical connector; and An electrical feedthrough assembly for an implantable leadless biostimulator according to any of the preceding claims, mounted on the housing, wherein the electrical feedthrough assembly for the implantable leadless biostimulator comprises an electrode body comprising a cup having an electrode wall extending distally from an electrode base surrounding an electrode cavity located on a longitudinal axis, and a pin extending proximally from the electrode base along the longitudinal axis to contact an electrical connector of an electronic device assembly, and wherein the cup and the pin are integrally formed so that the electrode body is unitary.

21. The biostimulator according to claim 20, wherein: The electrical feedthrough assembly for an implantable leadless biostimulator further comprises: an insulator having an insulator wall extending distally from an insulator base surrounding the electrode wall, wherein the insulator base is proximate to the electrode base, wherein an insulator bore extends through the insulator base along a longitudinal axis, and wherein the pin extends from the electrode base through the insulator bore to the electrical connector; and A flange is mounted on the housing and has a mounting wall extending around the insulator wall.

22. The biostimulator of claim 21, further comprising: a screw mounting member mounted on the flange; as well as A gasket has an annular body extending around the electrode wall, wherein the annular body is resiliently compressed between the screw mount and the mounting wall.

23. The biostimulator of claim 22, further comprising: a fixing element mounted on the screw mount, wherein the fixing element comprises a screw that rotates about a longitudinal axis in a first rotational direction; Therein, the screw mount is mounted on the flange via a threaded connection having a thread that rotates around the longitudinal axis in a second rotational direction opposite to the first rotational direction.

24. The biostimulator of claim 20, wherein: The electrical feedthrough assembly for an implantable leadless biostimulator also includes an electrode head mounted on the distal end of the electrode body, wherein the electrode head includes a terminal hole extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end.

25. The biostimulator of claim 24, wherein: A first diameter of the terminal aperture at the distal terminal end is smaller than a second diameter of the terminal aperture at the proximal terminal end.

26. The biostimulator of claim 20, wherein: The electrical feedthrough assembly for an implantable leadless biostimulator also includes a filler in the electrode cavity, wherein the filler includes a therapeutic agent in a silicone matrix.

27. The biostimulator according to claim 26, wherein: The electrical feedthrough assembly for an implantable leadless biostimulator also includes a retaining feature within the electrode cavity that maintains a filler at a predetermined position within the electrode cavity.

28. The biostimulator according to claim 27, wherein: The retention features include one or more protrusions extending from the electrode wall and contacting an outer surface of the filler.

29. The biostimulator according to claim 28, wherein: The one or more protrusions include a plurality of protrusions equally spaced about the longitudinal axis.

30. The biostimulator of claim 27, wherein: The retention feature includes one or more tabs formed by the electrode wall and bent inwardly into the electrode cavity.

31. The biostimulator of claim 27, wherein: The retention feature includes a lip extending circumferentially around an interior surface of the electrode wall and into the electrode cavity.

32. The biostimulator of claim 27, wherein: The retention feature includes a coil disposed within the electrode cavity, wherein the coil extends along a longitudinal axis and contacts an outer surface of the filler.

33. The biostimulator of claim 27, wherein: The retention feature includes a spring disposed within the electrode cavity, wherein the spring extends along a longitudinal axis and contacts an outer surface of the filler.

34. The biostimulator of claim 27, wherein: The retention feature includes a tubular spacer disposed within the electrode cavity, wherein the tubular spacer includes a through hole extending along a longitudinal axis.

35. The biostimulator of claim 27, wherein: The retention feature is a first retention feature and the electrical feedthrough further includes a second retention feature within the electrode cavity that maintains a filler at a predetermined position within the electrode cavity.

36. The biostimulator of claim 35, wherein: The first retention feature is integrally formed with the electrode wall, and the second retention feature is inserted into the electrode cavity.

37. The biostimulator of claim 36, wherein: The first retention feature is a plurality of protrusions extending inwardly toward the longitudinal axis, and the second retention feature is a coil inserted into an electrode cavity distal to the filler.

38. The biostimulator of claim 37, wherein: The plurality of protrusions consists of three protrusions evenly distributed around the longitudinal axis.

39. A method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator according to any one of claims 1 to 19, comprising: forming a distal portion of an electrode body, wherein the distal portion includes a cup having an electrode wall extending distally from an electrode base surrounding an electrode lumen located on the longitudinal axis; and A proximal portion of the electrode body is formed, wherein the proximal portion includes a pin that is integral with the cup, and wherein the pin extends proximally from the electrode base along the longitudinal axis.

40. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 39, further comprising: inserting the pin into the insulator hole through the insulator; as well as The pin is joined to the insulator by a brazed joint.

41. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 40, further comprising: inserting the insulator into the mounting hole in the flange; as well as The insulator is joined to the flange by a second brazed joint.

42. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 41 , further comprising inserting a filler into the electrode cavity such that the filler is placed in contact with a retention feature within the electrode cavity.

43. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature includes one or more protrusions extending from the electrode wall, and the method further includes forming the one or more protrusions.

44. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature includes a circumferential lip extending around the electrode wall, and the method further includes forming the circumferential lip.

45. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature includes one or more tabs cut from the electrode wall, the method further comprising forming the one or more tabs and pressing the one or more tabs inwardly toward the longitudinal axis.

46. ​​The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: A retaining feature of the one or more retaining features is insertable into the electrode cavity, the method further comprising inserting the retaining feature into the electrode cavity.

47. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is a coil disposed within the electrode cavity and extending along the longitudinal axis, and the method further includes inserting the coil into the electrode cavity after inserting the filler.

48. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is a spring disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the spring into the electrode cavity after inserting the filler.

49. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is a tubular spacer disposed within the electrode cavity and extending along the longitudinal axis, the method further comprising inserting the tubular spacer into the electrode cavity after inserting the filler.

50. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is integrally formed with the electrode wall and extends inwardly into the electrode cavity, the method further comprising forming the retention feature from the electrode wall.

51. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is insertable into the electrode cavity, and the method further includes inserting the retention feature into the electrode cavity.

52. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The retention feature is a first retention feature, and wherein inserting the filler into the electrode cavity further comprises inserting the filler into the electrode cavity such that the filler is placed in contact with a second retention feature within the electrode cavity.

53. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, wherein: The first retention feature is integrally formed with the electrode wall and the second retention feature is insertable into the electrode cavity, the method further comprising: forming the first retaining feature; and The second retention feature is inserted into the electrode cavity.

54. The method of manufacturing an electrical feedthrough assembly for an implantable leadless biostimulator of claim 42, further comprising: An electrode head is mounted on a distal end of the electrode body, wherein the electrode head includes a terminal hole extending through the electrode head along a longitudinal axis from the distal terminal end to the proximal terminal end, and wherein a first diameter of the terminal hole at the distal terminal end is smaller than a second diameter of the terminal hole at the proximal terminal end.

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