FIELD OF THE DISCLOSURE

The present disclosure pertains to implantable medical electrical devices suited for the delivery of cardiac therapy, and more particularly to electrode assemblies thereof.

BACKGROUND

An implantable medical electrical system of the type suited for cardiac rhythm management typically includes a pulse generator device to which at least one flexible elongate lead device is coupled to deliver stimulation therapy from the pulse generator to the heart of a patient. The pulse generator device is typically implanted in a subcutaneous pocket, remote from the heart, and the lead device extends therefrom to a cardiac implant site, either endocardial or epicardial, at which an electrode of the lead is secured in intimate engagement with myocardial tissue, according to methods known in the art. Electrodes of this type, which may pierce the myocardial tissue at the implant site, are typically included in a device electrode assembly that has means to elute a steroid for the treatment of inflammation at the site. In one such electrode assembly, for example, as described in commonly assigned United States Patent 7,184,839, a helical screw with a piercing tip, which forms an electrode, has a coating with a micro structure, such as titanium nitride, that holds a steroid solution, such as Beclomethasone. In other types of electrode assemblies, a steroid solution is loaded into a polymer, such as silicone rubber, that is formed into a component and mounted in proximity to the electrode.

SUMMARY

Various embodiments of implantable electrode assemblies disclosed herein include a steroid eluting component and are configured to enhance the

effectiveness of steroid elution from the component to the implant site.

A distal electrode of any of the assembly embodiments disclosed herein extends distally from a distal terminal end of a sleeve of the assembly, and the sleeve, which defines a longitudinal axis of the assembly, includes a plurality of channels that provide fluid communication between the steroid eluting component, which is seated in an external groove of the sleeve, and an area distal to the distal terminal end of the sleeve. According to some embodiments, floors of some or all of the plurality of sleeve channels angle toward the longitudinal axis of the assembly, being closer to the axis at the distal terminal end of the sleeve. Some assembly embodiments further include a proximal electrode secured to a proximal end of the sleeve, wherein the proximal electrode may be mounted around an outer surface of the sleeve or coupled to the sleeve by means of a coupling component.

According to some embodiments of a device, which includes any one of the electrode assembly embodiments, an elongate insulated conductor couples the distal electrode to a connector of the device by means of a conductive coupling component of the electrode assembly, which is mounted within the sleeve bore, secured to a proximal portion of the distal electrode that extends within the sleeve bore, and which engages with an inner surface of the sleeve to prevent rotation of the distal electrode relative to the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of the present disclosure and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in

conjunction with the explanations in the following detailed description.

Embodiments will hereinafter be described in conjunction with the appended drawings wherein like numerals denote like elements, and:

Figure 1 is a plan view of an exemplary implantable medical electrical lead device for cardiac stimulation, which may incorporate embodiments of the present invention;

Figure 2A is a perspective view of an electrode assembly, according to some embodiments;

Figure 2B is a perspective view of an electrode assembly, according to some alternate embodiments;

Figure 2C is a longitudinal cross-section view of a portion of the lead device that includes the assembly of Figure 2A, according to some embodiments; Figure 3A is a longitudinal cross-section view through a sleeve, according to some embodiments;

Figure 3B is an end view of the sleeve of Figure 3A, according to some embodiments;

Figure 3C is an enlarged detail view of a portion of the sleeve of Figure 3A, in proximity to a distal terminal end thereof, according to some embodiments;

Figure 4 is a perspective view of an electrode assembly, according to some additional embodiments;

Figure 5A is a longitudinal cross-section view through a sleeve of the Figure 4 electrode assembly, according to some of the additional embodiments;

Figure 5B is an end view of the sleeve of Figure 5A, according to some embodiments;

Figure 5C is an enlarged detail view of a portion of the sleeve of Figure 5A, in proximity to a distal terminal end thereof, according to some embodiments;

Figure 6A is a perspective view of a coupling component, according to some embodiments;

Figure 6B is a perspective view of another coupling component, according to some embodiments;

Figure 7A is a perspective view of an electrode assembly that includes distal and proximal electrodes, according to some additional embodiments;

Figure 7B is a longitudinal cross-section view of a sleeve of the Figure 7A electrode assembly, according to some embodiments; and

Figure 7C is a perspective view of the proximal electrode of the Figure 7A assembly, according to some embodiments.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides practical examples, and those skilled in the art will recognize that some of the examples may have suitable alternatives.

Figure 1 is a plan view of an exemplary implantable medical electrical lead device 200 for cardiac stimulation, which may incorporate embodiments of the present invention, for example, any one of electrode assemblies 202, 2021 , 402, 702, which are described in greater detail below. Figure 1 illustrates lead device 200 including an elongate body 214 that extends proximally from electrode assembly 202, 2021 , 402, 702 to a connector 206 of lead device 200. According to the illustrated embodiment, electrode assembly 202, 2021 , 402, 702 includes a distal electrode 220, which is coupled to a terminal pin contact 262 of connector 206 via an elongate insulated conductor 208 (Figure 2C), and may further include a proximal electrode 216, 716, which is coupled to a ring contact 258 of connector 206 via another elongate insulated conductor 212 (Figure 2C). Insulated conductors 208, 212 may be assembled together in a coaxial construction of body 214, which is known to those skilled in the art. Connector 206 is also constructed according to methods known in the art and is configured for connection to the aforementioned pulse generator device. An overall length of lead device 200 may be from about 25 inches to about 40 inches, so that when the pulse generator device is implanted in a subcutaneous pocket, for example, formed in the pectoral region of a patient, lead device 200 can extend therefrom to reach a cardiac implant site at which distal electrode 220 is engaged with the myocardium.

Figure 1 further illustrates an anchoring sleeve 204 mounted around body 214 to facilitate a securement of device body 214 in proximity to the pocket according to methods known to those skilled in the art.

Figure 2A is a perspective view of electrode assembly 202, according to some embodiments; and Figure 2B is a perspective view of electrode assembly 2021 , according to some alternate embodiments. Figures 2A-B illustrate electrode assembly 202, 2021 including a sleeve 218, which defines a longitudinal axis 2 of assembly 202, 2021 , and which has a distal terminal end 218D from which distal electrode 220 extends. According to the illustrated embodiment, distal electrode 220 is formed from a helical wire (e.g. 90/10 platinum iridum (Pt/lr) having a diameter of about 0.010 inch) that has a piercing distal tip for

engagement with the myocardium, a construction that is well known to those skilled in the art. With reference to Figure 2C, which is a longitudinal cross- section view of a portion of lead device 200 that includes assembly 202, a proximal portion 220P of distal electrode 220 is shown being mounted within an elongate bore 21 of sleeve 218 where a conductive coupling component 222 is secured thereto, for example, via a laser weld. Figure 2C further illustrates the aforementioned insulated conductor 208 being mechanically and electrically coupled to coupling component 222, for example, via a crimp formed between a proximal barrel 222P of component 222 and a distal end 208D of conductor 208, from which the insulation is removed. It should be understood that electrode assembly 2021 may also include the coupling between distal electrode 220 and conductor 208, via component 222, as illustrated in Figure 2C. A similar mechanical and electrical coupling may be formed between a proximal end of conductor 208 (not shown) and the aforementioned terminal connector pin 262 of connector 206 (Figure 1 ). According to an exemplary embodiment, insulated conductor 208 includes a 7x7 MP35N cable having an insulative coating of medical grade fluoropolymer, such as ethylene tetrafluoroethylene (ETFE), and may further include another layer of insulation in the form of a medical grade silicone rubber tube 210 in which the coated cable extends, a construction which is known in the art.

With reference to a longitudinal cross-section view of sleeve 218 in Figure 3A, sleeve 218 includes an external groove 250 that extends around bore 21 ; and, with further reference to Figures 2A-B and 3A, a plurality of channels 270 extend from a distal edge 250D of groove 250 to sleeve distal terminal end 218D, being formed in an outer surface of sleeve 218. Figure 2A illustrates electrode assembly 202 including a steroid eluting component 25 seated within external groove 250 of sleeve 218; and Figure 2B illustrates electrode assembly 2021 including a steroid eluting component 27, which is also seated within external groove 250 but also has a portion thereof extending within at least one of channels 270. In each of the Figures 2A-B embodiments, channels 270 provide fluid communication between steroid eluting component 25, 27 and an area distal to distal terminal end 218D of sleeve 218, which surrounds distal electrode 220. Thus, when electrode 220 is engaged with myocardium at the implant site, channels 270 can enhance the effectiveness of steroid elution from component 25, 27 to the implant site. Figure 3B is an end view of sleeve 218, according to some embodiments; and Figure 3C is an enlarged detail view of a portion of sleeve 218 in proximity to distal terminal end 218D, according to some embodiments. Figure 3B illustrates channels 270 uniformly spaced apart from one another around bore 21 , wherein the spacing may be about sixty degrees. A width Wch of each channel 270 may be about 0.006 inch in some embodiments, and, with reference to Figure 3C, a floor 270f of one of channels 270 is shown angling toward bore 21 of sleeve 218 (or toward longitudinal axis 2 of assembly 202 that includes sleeve 218 as shown in Figures 2A-B). Thus, floors 270f of some or all of channels 270 may be closer to bore 21 , or axis 2, at sleeve distal terminal end 218D. The angling of channel floors 270f can facilitate the elution of steroid from component 25, 27 to a location closer to electrode 220 (Figures 2A-B). With further reference to Figure 3C, according to an exemplary embodiment, an angle b that defines the angling of channel floor 270f may be about 15 degrees, a length Lc of each channel 270 may be about 0.010 inch, a depth Dg of groove 250 may be about 0.005 inch, and a width Wg of groove 250 may be about 0.016 inch.

With further reference to Figures 2A-B, according to some embodiments, steroid eluting component 25, 27 is formed from a medical grade silicone rubber that is loaded with a steroid, for example, a 2-part enhanced tear resistant silicone rubber (dimethyl and methyl vinyl siloxane copolymers reinforced with silica) loaded with dexamethasone acetate steroid, wherein a percentage composition by weight of the steroid may range from about 25% to about 30%. Component 25 may be molded into the form of a ring, separate from sleeve 218, and then seated within groove 250, being bonded thereto with an adhesive (e.g., a silicone medical adhesive) for securement thereto, according to some embodiments. In an exemplary embodiment, component 25 has a wall thickness of about 0.005 inch and a width Woo of about 0.014 inch to about 0.016 inch. Alternately, component 25, 27 may be insert molded into groove 250 (and channels 270 for component 27), according to methods known in the art, such that the seating and bonding of component 25, 27 is accomplished during the insert molding process. In either case, according to some preferred embodiments, an outer surface of component 25 is substantially flush with an outer surface of sleeve 218 on either side of groove 250 to maintain a substantially isodiametric profile of assembly 202, 2021 . According to some embodiments in which sleeve 218 is wholly formed from a medical grade polyurethane (e.g. having a hardness of about 55D), and in which component 25, 27 is formed from the aforementioned silicone rubber, groove 250 (and channels 270) can be plasma treated, according to methods known in the art, to enhance the surface(s) thereof for the bonding of component 25, 27 thereto. With further reference to Figure 2C and to Figure 3A, according to some embodiments, one or more additional channels 240 can extend through a floor 250f of groove 250, for example, to aid in the securement of component 25, 27 to sleeve 218 by allowing a flow of adhesive therethrough, or the flow of the material of component 25, 27 during molding, either of which can create a mechanical interlock between component 25, 27 and sleeve 218. In either case, one or more of channels 240 can also provide fluid communication between steroid eluting component 25, 27 and the area distal to sleeve distal terminal end 218D A diameter of each additional channel 240 may be about .010 inch.

With further reference to Figures 3A-B, according to some embodiments, an inner surface 201 of sleeve 218, which defines sleeve bore 21 , is formed so that the above described conductive coupling component 222 engages therewith, for example, being formed with flat portions, as seen in Figure 3B, to mate with flat portions 222f of coupling component 222 (Figure 2C). The engagement between sleeve 218 and conductive coupling component 222, which may be any suitable form of mechanical interlocking in addition to, or as an alternative to that described above, functions to prevent a rotation of distal electrode 220 relative to sleeve 218, for example, when an operator engages distal electrode 220 with myocardial tissue at the implant site by rotating electrode assembly 202 around axis 2 (e.g., by means of torque transferred through device body 214 from a proximal end thereof in proximity to connector 206).

Figure 4 is a perspective view of electrode assembly 402, according to some additional embodiments, which may be incorporated in lead device 200 of Figure 1. Figure 4 illustrates assembly 402 including a sleeve 418, which defines a longitudinal axis 4 of assembly 402, and which has a distal terminal end 418D from which distal electrode 220 extends. Figure 4 further illustrates electrode assembly 402 including a steroid eluting component 45, which is seated in, and secured to, an external groove 450 of sleeve 418, which can be seen in a longitudinal cross-section view of sleeve 418 shown in Figure 5A. Assembly 402 is similar in construction to that described above for assembly 202 (Figure 2C), but an inner surface of sleeve 418, which defines an elongate bore 41 of sleeve 418, has a plurality of channels 470 formed therein (rather than in an outer surface). With further reference to Figure 5A, additional channels 440 are shown extending through a floor 450f of groove 450 to provide fluid communication between groove 450 and channels 470, so that channels 470 essentially extend from groove 450 to sleeve distal terminal end 418D. Thus, channels 470 provide fluid communication between steroid eluting component 45 seated in groove 450 (Figure 4) and an area distal to distal terminal end 418D of sleeve 418, which surrounds distal electrode 220. According to some embodiments and methods, component 45, for example, formed from the same materials described above for components 25, 27, is insert molded into groove 450 and channels 440, and in some cases may further extend into at least one of channels 470.

Figure 5B is an end view of sleeve 418, according to some embodiments; and Figure 5C is an enlarged detail view of a portion of sleeve distal terminal end 418D, according to some embodiments. Figure 5B illustrates channels 470 uniformly spaced apart from one another around bore 41 , wherein, similar to channels 270 of sleeve 218, the spacing may be about sixty degrees, and a width Wch of each channel 470 may be about 0.006 inch. According to an exemplary embodiment, as in sleeve 218, a length Lc of each channel 470 may be about 0.010 inch, a depth Dg of groove 450 may be about 0.005 inch, and a diameter of each additional channel 440 may be about .010 inch. With reference to Figure 5C, a dashed line indicates an optional angling for a floor of at least one of channels 470 toward longitudinal axis 4 of assembly 402 that includes sleeve 418. Thus, floors of some or all of channels 470 can be closer to axis 4, at sleeve distal terminal end 418D, for example, to facilitate the elution of steroid from component 45 to a location closer to electrode 220.

With reference back to Figure 1 , the above described electrode assemblies 202, 2021 , 402 may also include one of the aforementioned proximal electrodes 216, 716, wherein proximal electrode 216 (Figure 2C) is configured for delivery of defibrillation therapy, and proximal electrode 716 (Figures 7A and 7C) is configured for delivery of pacing therapy. With reference to Figure 2C, proximal electrode 216 is shown being secured to sleeve 218 by means of a coupling component 620 mounted within sleeve bore 21 in proximity to a proximal end 218P thereof.

Figure 6A is a perspective view of coupling component 620, according to some embodiments. Figure 6A illustrates component 620 including a proximal portion 620P, a distal portion 620D, and a shoulder 620S located therebetween. Coupling component 620 further includes an elongate bore 602, which extends along a length thereof to allow passage of insulated conductor 208 therethrough, as seen in Figure 2C. Figure 2C further illustrates coupling component proximal portion 620P extending proximally from sleeve proximal end 218P, and coupling component distal portion 620D being mounted within sleeve bore 21 , for example, being secured to sleeve 218 by a bond that may be enhanced by threads formed along an outer surface of distal portion 620D. The bond between sleeve proximal end 218P and coupling component distal portion 620D may be formed by insert molding sleeve 218 over coupling component 620, or by using a polyurethane medical grade adhesive, wherein coupling component distal portion 620D may have a layer medical grade polyurethane formed thereover prior to forming the bond, when sleeve 218 is also formed from medical grade polyurethane. Proximal electrode 216, being suitable for the delivery of defibrillation therapy, is shown being formed by a coiled wire (e.g. 90/10 Pt/lr or tantalum wire having a

rectangular cross-section), and having a distal end 216D mounted around, and coupled to coupling component proximal portion 620P, for example, by laser welding methods known in the art. According to an exemplary embodiment, a distance between sleeve distal terminal end 218D and proximal electrode distal end 216D may be about 0.45 inch (1 1 mm - 12 mm), and a length of proximal electrode 216 may range from about 2 inches to about 2.5 inches (51 mm - 63.5 mm).

With further reference to Figure 2C, a proximal end 216P of proximal electrode 216 of electrode assembly 202 may be coupled to elongate insulated conductor 212 by means of another coupling component 630, a perspective view of which is shown in Figure 6B. Figure 6B illustrates the other coupling

component 630 including a distal portion 630D, a stepped proximal portion 630P, and a shoulder 630S located therebetween. With reference to Figure 2C, proximal electrode proximal end 216P is mounted around and coupled to distal portion 630D of the other coupling component 630, for example, by laser welding methods known in the art. With reference to Figure 6B in conjunction with Figure 2C, a first surface 630P-1 of the other coupling component proximal portion 630P supports a distal end of a conductive coil of insulated conductor 212, and a second surface 630P-2 of the other coupling component proximal portion 630P supports an outer insulation tube 21 1 that surrounds the conductive coil of insulated conductor 212.

Figure 7 A is a perspective view of an electrode assembly 702 that includes distal electrode 220 and proximal electrode 716, which is suitable for the delivery of pacing therapy, according to some additional embodiments. It should be noted that electrode assembly 702 may be incorporated by lead 200, in lieu of assembly 202, in a similar manner to that described above in conjunction with Figure 2C. Figure 7A illustrates a sleeve 718 of assembly 702, which defines a longitudinal axis 7 of assembly 702, and which includes a distal terminal end 718D, from which distal electrode 220 extends, for example, having the aforementioned proximal end 220P thereof mounted within an elongate bore 71 of sleeve 718 where the aforementioned conductive coupling component 222 is secured thereto as shown in Figure 2C. Figure 7A further illustrates electrode assembly 702 including the above-described steroid eluting component 25 that, similar to assembly 202, is seated in, and secured to, an external groove 750 of sleeve 718, which can be seen in the longitudinal cross-section view of sleeve 718 shown in Figure 7B. With reference to Figures 7A-B, sleeve 718 further includes a plurality of channels 770 extending from a distal edge 750D of groove 750 to sleeve distal terminal end 718D so that channels 770 provide fluid communication between steroid eluting component 25 and an area distal to sleeve distal terminal end 718D, which surrounds distal electrode 220. Figure 7B further illustrates sleeve 718 including one or more additional channels 740 that extend through a floor 750f of groove 750. Steroid eluting component 25 may be seated in, and secured to, groove 750 according to any of the methods described above for assemblies 202, 2021 , and exemplary dimensions for groove 750 and channels 770, 740 may be the same as those recited above for sleeve 218. Although Figures 7A-B show channels 770 being formed in an outer surface of sleeve 718, according to alternate embodiments of sleeve 718, channels 770 may be formed along an inner surface thereof like channels 470 of sleeve 418 (Figure 4). Furthermore, according to some embodiments, floors of some or all of channels 770 may be angled as shown for channel floor 270f of sleeve 218 in Figure 3C.

With further reference to Figures 7A-B, proximal electrode 716 of electrode assembly 702 may be in the form of a ring, being secured to a proximal end 718P of sleeve 718 by being mounted around an outer surface thereof. Figure 7B shows the outer surface of sleeve proximal end 718P being recessed so that an outer surface of mounted proximal electrode 716 may be flush with an adjacent outer surface of sleeve 718, according to some embodiments. Figure 7C is a perspective view of a component 730, which includes proximal electrode 716, according to some embodiments, and which may be constructed in a similar fashion to the above-described coupling component 630 that is employed in assembly 202 (Figures 2C and 6B). Figure 7C illustrates component 730 including a distal portion that forms proximal electrode 716 and a stepped proximal portion 730P, wherein a first surface 730P-1 of component proximal portion 730P supports a distal end of a conductive coil of an elongate insulated conductor (e.g. insulated conductor 212 of Figure 2C), and a second surface 730P-2 of component proximal portion 730P supports an outer insulation tube that surrounds the conductive coil of the insulated conductor (e.g., tube 21 1 of Figure 2C).

In the foregoing detailed description, the invention has been described with reference to specific embodiments. However, it may be appreciated that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims.