Patent Application
20090319014
This document pertains generally to implantable defibrillator leads.
Cardiac and other defibrillation systems typically include an implantable medical device (IMD), such as a pulse generator, electrically connected to the heart by at least one implantable defibrillator lead. More specifically, an implantable defibrillator lead provides an electrical pathway between the IMD, connected to a proximal end of the lead, and cardiac tissue, in contact with a distal end of the lead. In such a manner, electrical stimulation (e.g., in the form of one or more shocks or countershocks) emitted by the IMD may travel through the implantable defibrillator lead and stimulate the heart via one or more exposed, helically wound shocking coil electrodes located at or near the lead distal end portion. Once implanted, the exposed shocking coil electrodes often become entangled with fibrosis (i.e., a capsule of inactive tissue which grows into the exposed coils) with the end result being that a chronically implanted lead can be extremely difficult to remove by the application of tensile force to the lead proximal end.
Over time, situations may arise which require the removal and replacement of an implanted defibrillator lead. As one example, an implanted defibrillator lead may need to be replaced when it has failed, or if a new type of cardiac device is being implanted which requires a different type of lead system. As another example, bodily infection or shocking coil electrode dislodgement may require the replacement of an implanted defibrillator lead. In such situations, the implanted defibrillator lead may be removed and replaced with one or more different implantable leads.
To allow for easier removal, some implantable defibrillator leads include a fibrosis-limiting material covering a portion of the one or more otherwise exposed shocking coil electrodes thereon. When subjected to shear loads, such as during lead implantation procedures, the fibrosis-limiting material may separate from the associated shocking coil electrode or the shocking coil electrodes themselves may separate from the lead body or deform, thereby leaving uncovered coils that are subject to future fibrotic entanglement.
Certain examples include a lead comprising a lead body, at least one shocking coil electrode, and a fibrosis-limiting material. The lead body extends from a lead proximal end portion to a lead distal end portion. At least one shocking coil electrode is disposed along the lead body, for example, but not limited to, at one or both of the lead intermediate portion or the lead distal end portion. The shocking coil electrode optionally includes one or more laser welded portions. The fibrosis-limiting material coaxially surrounds, at least in part, the at least one shocking coil electrode. At least one passage is formed in the fibrosis limiting material, and bonding material, such as medical adhesive, is disposed over a portion of the coating and within the passage.
These and other examples, advantages, and features of the present leads and methods will be set forth in part in the detailed description, which follows, and in part will become apparent to those skilled in the art by reference to the following description of the present leads, methods, and drawings or by practice of the same.
In the drawings, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the present leads and methods may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the present leads and methods. The embodiments may be combined, other embodiments may be utilized or structural or logical changes may be made without departing from the scope of the present leads and methods. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present leads and methods is defined by the appended claims and their legal equivalents.
In this document, the terms “a” or “an” are used to include one or more than one, and the term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation.
The implantable defibrillator lead 104 transmits electrical signals between a selected location within, on, or about the heart 114 and the implantable medical device 102, such as to monitor the heart's 114 electrical activity at the selected location or to carry stimulation signals (e.g., one or more shocks or countershocks) to the selected location from the implantable medical device 102. The implantable defibrillator lead 104 may include a fixation assembly, such as one or more tines 118 or a helical coil, to anchor the lead distal end portion 118 at the selected location. The one or more tines 118 may be formed as part of the lead body 120, and thus may include a biocompatible lead body material, such as silicone rubber, polyurethane, polyimide, or a non-porous fluoropolymer. The fixation can be an active fixation assembly and/or a passive fixation assembly.
In this example, the lead intermediate portion 116 and the lead distal end portion 108 include one or more shocking coil electrodes, such as a first and a second shocking coil electrode 110. The first and second shocking coil electrodes 110 include an uninsulated, helically wound shocking coil formed of a non-corrosive, bio-compatible metal, such as platinum, titanium, or alloys (e.g., platinum/iridium). The shocking coil electrodes 110 are covered by a pliable fibrosis-limiting material 112 (e.g., polytetrafluoroethylene (PTFE) or expanded PTFE (ePTFE)) in direct contact with an outer surface 370 (
As shown in one option, the lead proximal end portion 106 includes one or more terminal leg connections 206 each of which is sized and shaped to couple to respective connector cavities incorporated into a header of the implantable medical device 102 (
Options for the fibrosis-limiting material 112 are as follows. For instance, the fibrosis-limiting material 112 may include PTFE, ePTFE, or other non-biodegradable and biocompatible materials, such as expanded ultra-high molecular weight polyethylene (eUHMWPE); may either be porous or non-porous; or may be inherently conductive or rely on porosity in conjunction with bodily fluids to be conductive. In various porous examples, the pore size is adequately small to allow penetration of conductive bodily fluids while substantially precluding tissue ingrowth, thus allowing a less traumatic removal of the defibrillator lead 104 after implantation should extraction become necessary. In various other examples, electrical conductivity through the fibrosis-limiting material 112 is not based on porosity, but rather is inherent in the material 112. For example, the fibrosis limiting material 112 is such that it can transfer electrical energy from the surface of the underlying electrode coil to the cardiac tissue it is in contact with. At least a portion of the outer surface of this material 112 is adapted to stimulate cardiac tissue, by being inherently electrically conductive, without relying on porosity and body fluid for charge transfer. The material 112 serves as the substrate for providing an electrically conductive path by way of either any suitable electrically conductive coatings deposited on the polymer surface, or any suitable electrically conductive particles blended with the polymer, prior to converting it to the final form. Examples of the substrate polymers include but are not limited to silicone rubber, polyurethane, and homopolymers or copolymers of polyolefin, fluoropolymer, polyamide and polyester. Examples of electrically conductive coatings on these polymers include but are not limited to coatings based on platinum, palladium, iridium, cobalt, silver, nickel and combinations thereof. Such coatings may be deposited by any methods commonly used in the industry, such as electrodeless deposition, plasma deposition, sputtering or chemical vapor deposition. In a further example, the fibrosis-limiting material 112 is wrapped around the coil electrode, for example, out of one or more strands of material.
Further options for the fibrosis limiting material 112 can be seen in
In an option, the through hole 138 extends from the exterior portion 134 through the interior portion 136 of the fibrosis limiting material 112. In another option, multiple rows of through holes 138 are disposed in the fibrosis limiting material 112, such as two or more rows of holes 138. In an option, multiple through holes 138 are disposed within the fibrosis limiting material 112, for instance disposed around a perimeter of the of the fibrosis limiting material 112. In a further option, the through hole 138 has a circular cross section. Other options for the passage include, but are not limiting to, a slit, recess, or slot.
Bonding material 140, such as, but not limited to, medical adhesive, is disposed over the coil electrode 110, over and under a portion of the fibrosis limiting material 112 and through the through hole 138 creating an interlock, such as a mechanical interlock so that the fibrosis limiting material 112 remains connected with the electrode 110 even when subjected to various forces, as further discussed below. In an option, the bonding material 140 is similar in appearance such as color and/or texture as the fibrosis limiting material 112 so that the passage 138 is less conspicuous.
Portions of the fibrosis limiting material, such as ePTFE, are completely surrounded by the bonding material such that the bonding material only relies upon bonds to itself and the tubing within, and does not necessarily rely on a bond between the bonding material and the fibrosis limiting material. The bonding material that passes under the coating of fibrosis limiting material and around the coil electrode 110 assists in maintaining the coil electrode 110 static even when it is manipulated and subjected to various forces. In addition, the bonding material can be used to create a tapered transition to avoid rough edges on the coil electrode.
In an option, the shocking coil electrode 110 includes at least one treated portion such as, but not limited to, a laser weld portion 420. In an option, the laser weld portion 420 includes a coil through hole 142 (
The at least one laser weld portion 420 is formed, for example, by laser welding the shocking coil electrode 110, for example, with a laser band that extends 360 degrees around the shocking coil electrode 110. In an option, the at least one laser weld portion 420 is included at one or more end portions 113 of the shocking coil electrode 110. In a further option, the laser weld portion is formed on one or more filars of the shocking coil electrode 110. For example, the laser weld portion is formed, in an option, two or more filars of the shocking coil electrode 110, and in another option on 8-12 filars of the shocking coil electrode 110. In another option, about 5 mm of the shocking coil electrode 110 is formed inflexible, for example with the laser weld. In a further option, the filars are close wound coils. In a further option, multiple portions of the shocking coil electrode 110 can include laser weld portions 420, such as shown in
The laser weld portions 420 can extend partially around the shocking coil electrode 110, or can extend 360 degrees around the shocking coil electrode 110. In a further option, for instance as shown in
The fibrosis-limiting material 112 coaxially covers the shocking coil electrode 110 and the laser weld portions 420 in a tightly conforming manner, in an option, and the laser weld portion 420 improves adhesive of the fibrosis limiting material 112 to the shocking coil electrode 110. For instance, the laser weld creates a relatively smooth surface for the fibrosis limiting material to attach to. In an option, the fibrosis-limiting material 112 extends to the ends of the shocking coil electrode 110. In a further option, the fibrosis limiting material 112 extends to less than a length of the shocking coil electrode 110. In yet another option, the fibrosis limiting material 112 extends to greater than a length of the shocking coil electrode 110.
In a further option, the laser weld portion 420 is at one more end portions 113 of the shocking coil electrode 110, and in an option is at each of the end portions 113 of the shocking coil electrode 110. The laser weld portion 420 includes at least one slit therein, and in an option the at least one slit is provided at each of the end portions 113. In an option, the at least one slit includes two slits formed, for example, on opposite sides of the shocking coil electrode 110. The slit allows for the shocking coil electrode 110 and/or the laser weld portion 420 to radially expand, for example, by 0.005-0.010 inches.
In a further option, the fibrosis-limiting material 112 is disposed over the laser band portion 420 and the shocking coil electrode 110 after the at least one slit 422 is formed in the laser band portion 420. The shocking coil electrode 110 can be expanded to fit over a fitting via the at least one slit, and the expanded shocking coil electrode 110 puts radial tension in the fibrosis-limiting material 112, such as ePTFE, and increases resistance of movement of the fibrosis-limiting material 112 relative to the shocking coil electrode 110, and/or increases the adhesion between the fibrosis limiting material and the shocking coil electrode 110.
Implantable defibrillator leads 104 are placed in contact with cardiac tissue by passage through a venous access, such as the subclavian vein, the cephalic vein, or one of its tributaries. In such a manner, an implantable defibrillator lead 104 may advantageously be placed in contact with the heart 114 (
When a physician implants a defibrillator lead 104, such as through the introducer sheath 600 and specifically an introducer seal 604, high drag forces may be created along the lead body 120. As a result of these high drag forces, previous lead component interfaces including the fibrosis-limiting material 112 to shocking coil electrode 110 and the shocking coil electrode 110 to the lead body 120 could separate or shift relative to one another leaving uncovered coil portions subjected to future fibrotic entanglement (e.g., the shocking coil electrode 110 became stretched, which in turn pulled the fibrosis-limiting material 112 away from the coil 110 and exposed a portion of the coil to fibrotic growth). Using the present lead manufacturing technologies, it has been found that such separating or shifting between the fibrosis-limiting material 112, the shocking coil electrode 110, and the lead body 120 is reduced or eliminated, thereby preventing fibrotic entanglement and facilitating lead extraction should it become necessary.
A method of manufacturing an implantable defibrillator lead including robust attachment between a fibrosis-limiting material, a shocking coil electrode, and a lead body is described herein. The lead assembly is formed including winding at least one electrode coil, and optionally laser welding at least a portion of at least one electrode coil, for example, but not limited to at one or more ends of the coil, and/or at one or more discrete locations of the coil, and/or helically along the coil, and/or around 360 degrees around the coil. The laser welding can be done in the various embodiments discussed above, and/or illustrated in the drawings. In a further option, one or more slits are formed in the laser welded portions, for example with two slits.
A fibrosis-limiting material is coated, for example coaxially fitting the material over at least one shocking coil electrode. In various examples, this coaxially fitting includes positioning a portion of the fibrosis-limiting material proximal or distal to a shocking coil electrode end. The fibrosis-limiting material is formed onto an outer surface of the at least one shocking coil electrode, such as through the use of heat.
The method includes forming at least one passage in the coating, and disposing bonding material over and under at least a portion of the coating and through the passage. In an option, a plurality of through holes are formed in the coating. In an option, the method includes forming at least one coil though hole in the coil, such as through a rigid portion, for instance the laser welded. The coil through hole is fluidly coupled with the passage so that the bonding material can be disposed through both the passage and the coil through hole. The method further includes coupling one or more portions, such as end portions, of the at least one shocking coil electrode to a lead body or component. Optionally, the coupling between the shocking coil electrode and the lead body includes the use of an adhesive.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For instance, any of the aforementioned examples may be used individually or with any of the other examples. In addition, the aforementioned examples may or may not include the use of adhesives (e.g., medical adhesives) for selected component attachment. Many other embodiments may be apparent to those of skill in the art upon reviewing the above description. The scope of the present leads and methods should, therefore, be determined with reference to the appended claims, along with the full scope of legal equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, assembly, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of such claim.
The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together to streamline the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may lie in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
This application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application Ser. No. 61/051,269, filed on May 7, 2008, which is incorporated herein by reference in it entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61051269 | May 2008 | US |
