Medical electrical lead with interchangeable fixation member

Abstract

A medical electrical lead, a system for providing electrical stimulation or sensing using such a lead, and methods of implanting, making and using same are described. The lead includes a rapidly connectable and/or interchangeable distal line that may be attached to a connector located distally from a distal end of a stimulating electrode. The rapidly connectable or interchangeable line may be sutured to a patient's muscle or other tissue. A physician may select a distal suture line of the present invention on the basis of the desired characteristics of the line, and then connect, secure or attach same to the lead body just prior to the surgical operation in which the stimulating or sensing medical electrical lead of the present invention is to be employed. The desired characteristics of the suture line may relate to thickness or diameter, length, the material from which the line is made, biodegradability, and the like.

Description

RELATED DISCLOSURES

This application is a continuation application of U.S. application Ser. No. 10/132,513, filed Apr. 26, 2002, now pending, which is a continuation-in-part of U.S. application Ser. No. 09/487,787, filed Jan. 20, 2001, now issued, U.S. Pat. No. 6,434,431 issued Aug. 13, 2002. The entire content of each of these U.S. Applications is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to medical electrical medical leads, including intramuscular medical electrical leads.

BACKGROUND OF THE INVENTION

Surgically implanted medical electrical leads for temporary stimulation of various organs in the human body are known in the art, some examples of which may be found in the issued U.S. Patents listed in Table 1 below.

TABLE 1
U.S. Pat.
No.       Title
3,474,791 Multiple Conductor Electrode
3,682,162 Combined Electrode and Hypodermic Syringe Needle
3,757,790 Threshold Analyzer and Stimulator Testing Device with
          Internal Generator
4,245,643 Method and Apparatus for Measuring the Ohmic Contact
          Resistance of an Electrode Attached to Body Tissue
4,408,617 Apparatus for Detecting the Acupuncture Points on a Patient
          and for Applying Electrical Stimulating Signals to the
          Detected Points
4,444,207 Method of Anchoring a Temporary Cardiac Pacing Lead
4,735,205 Method and Apparatus Including a Sliding Insulation Lead for
          Cardiac Assistance
5,300,107 Universal Tined Myocardial Pacing Lead
5,314,463 Bipolar Nerve Electrode
5,423,876 Intramuscular Lead Having Improved Insertion
5,425,751 Method and Apparatus for Optimum Positioning of a Muscle
          Stimulating Implant
5,755,758 Intramuscular Stimulation Lead with Enhanced Infection
          Resistance
5,792,217 Temporary Bipolar Heart Wire
5,834,051 Intramuscular Stimulation Lead with Enhanced Infection
          Resistance
5,871,528 Temporary Bipolar Heart Wire
5,928,278 Defibrillation Electrode
5,938,596 Medical Electrical Lead

Medical electrical leads and other medical devices having various types of loops disposed therein or thereon are also known in the art, some examples of which may be found in the issued U.S. Patents listed in Table 2 below.

TABLE 2
U.S. Pat.
No.       Title
4,317,459 Fixation Loop for Transvenous Leads
5,207,226 Device and Method for Measurement of Blood Flow
5,555,883 Loop Electrode Array Mapping and Ablation Catheter for
          Cardiac Chambers

Incorporated by reference herein, each in its respective entirety. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, at least some of the devices and methods disclosed in the patents of Tables 1 and 2 may be modified advantageously in accordance with the teachings of the present invention.

In respect of known intramuscular medical stimulation leads, sliding members disposed on the lead bodies thereof may act as a source of bacterial infection. See, for example, the '758 patent referenced in Table 1 hereinabove. Additionally, non-conductive polypropolene monofilaments employed in known intramuscular leads have been criticized as being too stiff and difficult to tie into a knot. Moreover, fixation of the aforementioned sliding members to muscle tissue is not always possible. Indeed, such sliding members have a tendency to move after a suture has been applied around the barrel anchor thereof. There also exists the problems of temporary electrical stimulating leads having suture wires affixed thereto which are determined to be difficult to suture by the physicians who implant them, or which should or must be removed post-operatively from the patient.

Thus, there exists a need to implant temporary stimulation leads for intramuscular and other applications which employ suture wires that are not prone to infection, need not be removed post-operatively from patients, or which are easier to implant.

SUMMARY OF THE INVENTION

The present invention has certain objects. That is, the present invention provides solutions to problems existing in the prior art. It is an object of the present invention to provide an intramuscular or other medical electrical lead, which may be reliably and quickly affixed to muscle or other issue. It is further object of the present invention to provide an intramuscular or other medical electrical lead, which is quickly and easily attached to human muscle or other tissue. It is a still further object of the present invention to provide an intramuscular or other medical electrical lead which easier to implant than prior art leads.

Various embodiments of the present invention have one or more advantages, including one or more of the following: (a) reducing the amount of time required to implant an intramuscular lead in muscle tissue; (b) permitting one or more electrodes to be reliably and fixedly implanted within is human muscle tissue; (c) reducing patient trauma; (d) reducing the number of puncture sites in the muscle tissue; (e) is easy to use; (f) attaching to external pacemakers, defibrillators, monitoring equipment and other external electrical apparatus quickly, easily, securely and reliably; (g) increasing patient safety owing to shortened implantation times, quicker connection to external stimulation or monitoring equipment, and more reliable fixation to muscle tissue; (h) eliminating the requirement for post-operative removal of suture wires from the patent; (i) permitting the implanting physician to select from an array of different suture wires that may be quickly connected to the lead.

Various embodiments of the intramuscular medical electrical lead of the present invention have certain features, including one or more of the following: (a) an intramuscular lead having at least one proximal fixation member; (b) an intramuscular medical electrical lead having at least one distal fixation member; (c) an intramuscular medical electrical lead having proximal and distal fixation members, (d) an intramuscular medical electrical lead having a proximal or distal fixation member, where the fixation member is selected from a group consisting of a trumpet-shaped member, a tined member, and a helical screw; (e) an intramuscular medical electrical lead having an electrode section which may be elongated or compressed during the implantation procedure; (f) an intramuscular or other medical electrical lead having an absorbable or resorbable suture wire section; and (g) an intramuscular or other medical electrical lead having a suture wire section which may be readily installed, swapped or replaced, according to the is particular requirements of the physician who implants the lead.

Other objects, features, advantages and embodiments of the present invention will become apparent upon reading the Detailed Description of the Preferred Embodiments and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art intramuscular lead;

FIG. 2 shows one embodiment of an intramuscular lead of the present invention;

FIG. 3 shows a cross-sectional view of one embodiment of an intramuscular lead of the present invention implanted in muscle tissue:

FIG. 4 shows two embodiments of an intramuscular medical lead of the present invention implanted within muscle tissue and connected to an implantable electrical stimulator;

FIG. 5 shows a perspective view of a one embodiment of an intramuscular medical electrical lead and corresponding electrical stimulator implanted within the human body in accordance with a dynamic graciloplasty surgical procedure;

FIG. 6(a) shows disk trumpet-and/or disk-shaped embodiments of the distal and proximal fixation members of the present invention;

FIG. 6(b) shows helical screw-and/or cone-shaped embodiments of the distal and proximal fixation members of the present invention;

FIG. 6(c) shows a cross-sectional view of the helical screw-shaped is embodiment of the proximal fixation member illustrated in FIG. 6(b);

FIG. 6(d) shows tin-shaped embodiments of the distal and proximal fixation members of the present invention;

FIG. 6(e) shows further embodiments of tine-shaped embodiments of the distal and proximal fixation members of the present invention;

FIG. 7(a) shows a cross-sectional view of one embodiment of a variable length and flexibility electrode implanted within human muscle tissue;

FIG. 7(b) illustrates the mechanical principles involved in varying the flexibility of the electrode illustrated in FIG. 7(a);

FIG. 7(c) shows one embodiment of the electrode of FIG. 7(a) in cross-section in the region of the distal portion thereof,

FIG. 7(d) shows yet another embodiment of the electrode of FIG. 7(a) in cross-section in the region of the distal portion thereof;

FIG. 8(a) shows one embodiment of a medical electrical lead of the present invention having a replaceable or resorbable suture wire forming portions of the distal end thereof,

FIG. 8(b) shows another embodiment of a medical electrical lead of the present invention having a replaceable or resorbable suture wire forming portions of the distal end thereof; and

FIG. 9 shows one embodiment of a medical electrical lead of the present invention having a breakable or snappable needle attached to the distal end thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a prior art intramuscular medical electrical lead disclosed in U.S. Pat. No. 4,735,205 to Chachques et al. entitled “Method and Apparatus for a Sliding Insulation Lead for Cardiac Assistance”. In FIG. 1, pulse generator 5 (not shown in FIG. 1) is coupled to intramuscular lead 30 comprising suture needle 32, distal member or line 33, pigtail coil 34, lead body 36, IPG connector 38, slidable insulating tube or sheet 42 and electrode 44. Suture needle is adapted to be drawn through the muscle which is to be electrically stimulated. Electrode 44 is implanted within the desired muscle by being drawn therethrough using line 33 attached to suture needle 32. Needle 32 is first inserted through the muscle and electrode 44 drawn therethrough by means of line 33. Connector 38 is adapted for coupling to one or more output terminals of implantable pulse generator (IPG) 5 after electrode 44 has been appropriately implanted in muscle tissue.

FIG. 2 illustrates one embodiment of an intramuscular medical electrical lead of the present invention. Medical electrical lead 30 in FIG. 2 comprises proximal IPG connector 30, lead body 36, proximal fixation member 10, electrode 44, distal fixation member 15, line 33, needle 32, temporary testing wire 19, and test connector 20. Needle 32 may further comprise pointed electrically conductive tip 32a and portion 32b having electrically insulative material disposed thereover. Note that in various embodiments of the present invention only one fixation disk member 10 or 15 is may be present. Fixation member 10 is preferably fixedly attached to lead body 36 and/or electrode 44, while distal fixation member 15 is preferably attached to the distal end of electrode 44 after electrode 44 has been suitably positioned and placed within muscle tissue and needle 32 has been removed by the physician from the distal end of lead 30. In one such embodiment of the present invention, distal fixation member 15 forms a circular disk having a hole disposed through the center thereof through which line 33 is threaded, with fixation member 15 then being slid proximally up line 33 until it engages the distal end of electrode 44 and is snapped or clicked into place thereover for relatively rigid fixation thereto.

Prior to implanting electrode 44, an optimum electrode implantation location may be determined as follows. To determine the best location for muscle implant 44, threshold measurements at various test locations may be carried out on the muscle. One consideration in evaluating such a location is whether a location requires only a low threshold stimulation signal (and hence low energy consumption) to cause muscle contraction. Obviously, locations having the lowest stimulation thresholds are preferred. Another consideration in evaluating a stimulation location is whether stimulation at such a location causes muscle contractions to be large. It is generally preferred that muscle contractions be large. The foregoing two considerations are generally weighed together in determining an optimum electrode location.

In the present invention, an optimal electrode position may be determined by using needle 32, and more particularly needle point 32a, as a is test electrode probe. Needle point 32a is placed in, contact with various test locations on the surface of a muscle. Temporary conductor or test wire 10 is provided for supplying electrical current to needle 32 from an external pulse generator (not shown). Because needle 32 must be gripped by the surgeon during the testing of prospective implant electrode locations, the outside surface of the proximal gripping portion of needle 32 spaced from sharp muscle-contacting probe end 32a thereof may be provided with a suitable insulating coating 32b such as a polyurethane adhesive. Distal end 32a of needle 32 must make electrical contact with the muscle tissue being tested and therefore is not insulated. It will be understood by those skilled in the art that needle 32 need not be coated to be functional.

Use of needle 32 for testing relation of a muscle tissue area is accomplished by gripping the insulated surface 32b thereof and holding the uninsulated contact point area 32a and electrical contact for selected test areas of the muscle tissue. There is a risk of local tissue damage if sharp point 32a of needle 32 penetrates the surface of the muscle. Non-penetrating contact has therefore been found to be preferable to inserting the sharp end of the needle into the tissue.

After testing the various prospective implant locations, determining the optimum location, temporary conductor or test wire 10 is severed adjacent to its attachment point with needle 32. Needle 32 is then employed by the surgeon to penetrate the targeted muscle and permit electrode 44 of lead 30 to be drawn into an optimum position for periodic stimulation.

In a preferred embodiment to the present invention, line 33 is electrically nonconductive and is made of an absorbable or bioabsorbable suture material so that it is eventually absorbed by the muscle tissue after implant. Such materials include DEXON®, VICRYL®, MAXON® and PDS®.

In another embodiment of the present invention, nonconductive line 33 is replaced with a thin conductor wire having an outer insulative coating such as is preferably the case with temporary conductor or test wire 10. Connector 38 is connected to implantable pulse generator 5 (not shown in FIG. 2). Once the optimum electrode stimulation location has been determined, electrode 44 is inserted in the targeted muscle, followed by cutting temporary conductor wire 10 at the end located near needle 32.

Continuing to refer to FIG. 2, line or member 33 is most preferably a monofilament wire formed of polypropylene. Lead body 36 may comprise any suitable flexible electrical conductor, such as strands of multifilament or twisted stainless steel. Lead body 36 most preferably comprises an electrical conductor that provides a high degree of flexibility and superior mechanical and electrical properties. In preferred embodiments of the present invention the electrical conductor of lead body 36 is covered with an appropriate electrical insulator such as silicone rubber, polyurethane, polyethylene, polypropylene, polyamide, combinations and mixtures of the foregoing, and other suitable materials. The electrical conductor disposed within lead body 36 is most preferably formed from twisted or helically wound strands of medical grade stainless steel wire. Less preferably, the conductor may be formed of single strands of stainless steel, or of one or more strands of electrically conductive polymeric material.

The insulation disposed over the electrical conductor is most preferably formed of flourinated ethylenepropylene ((FEP), polytetrafluoroethylene (PTFE), or any other suitable medical grade, biocompatible dielectric insulating coating such as co-polymer polytetrafluoroethylene, polyethylene, silastic, neoprene, polypropylene, or polyurethane. Likewise, proximal and distal fixation members 10 and 15 may be formed of the same or similar materials.

Electrode 44 is most preferably formed of a platinum/iridium alloy, wherein platinum comprises 90 percent of the alloy and iridium comprises 10%. Electrode 44 is mechanically and electrically connected by an electrical conductor disposed within lead body 36 (not shown in the Figures). The electrical conductor, in turn, is attached to the distal end of IPG connector 38. Lead 30 includes current needle 32 for piercing muscle tissue preparatory to drawing electrode 44 within the muscle tissue. The proximal end of curved needle 32 is connected to line or strand 33.

Referring now to FIG. 31 there is shown a cross-sectional view of patients muscle tissue 27 having one embodiment of lead 30 of the present invention disposed therein. Scissors 39 are employed by a physician to grip portions of needle 32 and draw electrode 44 through and into a desired portion of muscle tissue 27. Proximal fixation member 15 prevents or impedes pulling lead body 36 into muscle tissue 27. In similar fashion, distal fixation member 10 (once in place) prevents portions of electrode 44 from moving outside muscle tissue 27 in the proximal direction. Optional anchoring sleeve 25 may be employed to appropriately locate or position lead body 36 in a desired location.

In preferred embodiments of the present invention, lead 30 is configured to provide satisfactory stimulation thresholds for appropriate muscle contraction of muscle tissue 27. Needle 32 is appropriately shaped and of appropriate length to provide optimum results. The length of lead 30 should be sufficient to provide adequate slack in lead body 36 to permit bi-lateral implants. Moreover, in a preferred embodiment of the present invention proximal and distal affixation members 15 and 10, respectively, optionally include structures for suturing or anchoring same to muscle tissue 27 once electrode 44 has been appropriately positioned within same. It is also desired that at least portions of lead 30 be visible using x-ray imaging techniques.

Referring now to FIG. 4, there is shown intramuscular stimulating system 3 comprising IPG 5 and two leads 30 appropriately implanted in intramuscular tissue 27 such that electrodes 44 thereof provide appropriate electrical stimulation to tissue 27. Curved needles 32 of lead 30 are removed by the physician once distal affixation member 10 has been placed or located at or near the distal end of electrodes 44. In a preferred embodiment of the present invention, electrode 44 is about 25 mm in length, although other electrode lengths are contemplated in the present invention including, but not limited to, about 5 mm, about 10 mm, about 16 mm, about 20 mm, about 25 mm, about 30 mm, about 35 mm and about 40 mm.

FIG. 5 shows intramuscular stimulating system 3 comprising IPG 5 and leads 30. IPG 5 may be, for example, a Medtronic Model No 3023 Interstim IPG. Such an IPG may be programmed using a Medtronic Model No. 3031 Patient Programmer. In the embodiment of system 3 of the present invention illustrated in FIG. 5, a gracilis muscle 29127 is wrapped around portions of anus 31. Gracilis muscle 29127 is then electrically stimulated through means of electrodes 44 implanted therewithin, such electrodes being electrically connected to IPG 5. The configuration of gracilis muscle 29/27 illustrated in FIG. 5 is known as a dynamic graciloplasty procedure.

FIGS. 6(a) through 6(c) illustrate various embodiments of the proximal and distal fixation members of the present invention. In FIG. 6(a), electrode 44 is positioned within muscle 27, and is secured reliably and relatively fixedly therein through means of proximal and distal affixation members 10 and 15, respectively. As shown in FIG. 6(a), proximal fixation member may from a toroid-shaped member fabricated most preferably from silicon rubber. Distal fixation member 15 is shown as comprising snap-on disk 15a having a central hole disposed therethrough through which line 33 is threaded, snap-on disk then being pushed over distal cone or member 15b for frictional engagement thereof. It is contemplated in the present invention that any of the proximal and distal fixation members 10 and 15 illustrated in any of the Figures hereof may be positionally switched.

In FIG. 6(b), proximal fixation member 10 is of the helical screw-in type. Distal fixation member 15 again comprises cone 15b and snap-on disk 15a. FIG. 6(c) shows a cross-sectional view of portions of lead 30 in the vicinity of screw-in fixation member 10 in FIG. 6(b). Crimp sleeve 65 slides over helical screw 10 and crimps same to electrical conductor 41 and electrode 44. Electrical insulation 37 may be disposed between helical screw-in member 10 and electrode 44.

FIG. 6(d) illustrates yet another embodiment of the present invention, where proximal and distal fixation members 10 and 15 comprise tined members that prevent or inhibit movement of electrode 44 following implantation within muscle tissue 27. Tines attached to fixation member 10 in FIG. 6(d) project proximally and inhibit movement of electrode 44 in the proximal direction. Contrariwise, in the embodiment of the present invention illustrated in FIG. 6(d) tines attached to proximal fixation member 10 prevent or inhibit movement of electrode 44 in the distal direction.

FIG. 7(a) illustrates muscle tissue 27 in cross-section having yet another embodiment of the lead of the present invention implanted therein. Disk-shaped proximal fixation member 10 prevents electrode 44 from moving in the distal direction, while similarly-shaped distal fixation member 15 prevents movement of electrode 44 in the proximal direction once electrode 44 has been appropriately positioned within muscle tissue 27. In the embodiment of the present invention shown in FIG. 7(a), distal fixation member 15 most preferably comprises circular disk 15b having a central hole is disposed therethrough through which line 33 is threaded, the hole being dimensioned and configured to snappingly engage a rim or groove disposed in cone 15b.

As shown in FIGS. 7(a) and 7(b), an alternative embodiment of electrode 44 comprises relatively tightly wound electrode wire which is capable of being pulled apart to thereby elongate electrode 44 and to increase the flexibility thereof. Additionally, electrode 44 may also be shaped such that spaces are initially disposed between adjoining windings thereof. In such an embodiment of the present invention, those windings may be pushed together to increase the stiffness of electrode 44 or pulled apart to increase the flexibility thereof.

Referring now to FIGS. 7(c) and 7(d) there are shown two different embodiments for securing wound electrode 44 illustrated in FIGS. 7(a) and 7(b) to distal portions of lead 30. Cone-shaped member 15b may be configured to crimpingly engage distal portions of wound electrode 44 in the region of sleeve 35. Alternatively, crimp sleeve 35 may be configured such that portions of lead 30 disposed distally therefrom may be separated from lead 30 using surgical scissors or mechanical breaking or snapping of a weakened zone.

The present invention includes within its scope methods of implanting, using and making the leads described hereinabove. For example, the invention includes a method for implanting an intramuscular lead having distal and proximal ends, the lead being suitable for electrical stimulation or sensing of muscle tissue and comprising at least one stimulating and/or sensing electrode, the lead further comprising at least one of a proximal fixation member located proximally from the electrode and a distal fixation member located distally from the electrode, the method comprising: (a) positioning the at least one electrode in electrical contact with at least a portion of muscle tissue, the electrode being electrically connected to at least one electrical conductor, the conductor having a proximal end connected electrically to a proximal connector, the connector being configured for attachment to an external electrical apparatus; (b) securing the electrode to the at least portion of the muscle tissue; and (c) positioning at least one of the proximal fixation member and the distal fixation member in or on the muscle issue to prevent or inhibit movement or relocation of the at least one electrode in the distal or proximal directions.

The Figures show disk-shaped fined, trumpet-shaped, sleeve-shaped, cone-shaped, and helical screw proximal and distal fixation members 10 and 15, respectively, but any suitably shaped or configured fixation member, whether proximal or distal, may be employed. The fixation member may be formed of polyurethane, silicon rubber, medical grade plastic, suitable to biocompatible polymers, stainless steel or any other suitable biocompatible, biostable material. Additionally, either or both of the proximal and distal fixation members may be fixedly attached to regions near the proximal and distal ends of the electrode, respectively, or may be attachable to such regions after the electrode has been implanted in the muscle tissue at the desired site. For example, a fixation member may assume a split disk configuration or shape having two portions which snap together when closed upon one another, where the two portions are opened for placement around the lead body, electrode crimping sleeve, cone-shaped member or the electrode, and are then closed therearound by snapping the two portions together. As discussed above, one of the fixation members may slide onto the line or member 33, and then be moved in the distal or proximal directions into a position where the fixation member snappingly or otherwise engages at least portions of a locking member or cone to thereby be secured into position.

It is also not a requirement of the present invention that the fixation members be located precisely “at” the proximal or distal end of the electrode. Instead, either fixation member may be attached, by way of example only, to a location disposed proximally or distally from the electrode, to a location on the lead body disposed distally from the electrode, to a location disposed proximally from the electrode, to member 33, or even to other members or portions of lead 10. What is important is that the electrode be reliably and relatively fixedly positioned within the muscle tissue at a desired site through means of the one or more fixation members, and that such positioning of the electrode be so maintained over a desired period of time.

Line or member 33 need not be electrically nonconductive, and may be formed integrally with, by way of example only, electrode 44 or lead body 36. Line or member 33 may also include a coil affixation member, such as a pigtail, therein.

FIG. 8(a) shows one embodiment of a medical electrical lead of the present invention having replaceable or resorbable suture wire 33 forming portions of the distal end thereof. In the embodiment of suture 33 illustrated in FIG. 8(a), suture 33 forms a loop which is drawn through eyelet 62 formed in distal connector 51. Suture 33 is looped through eyelet 52, and its two ends terminate where they are attached to the proximal end of needle 32. The attachment of those two ends to the proximal end of needle 32 may be through welding, swaging, thermosetting, crimping, typing, knotting, gluing, and other means known in the art. Attachment may be accomplished when the lead is manufactured, or alternatively be accomplished just before the lead is implanted when the implanting physician selects a suture material, which he prefers to employ, and attaches same to the lead.

For example, the physician himself may crimp, glue, tie or otherwise attach the two ends of suture 33 to the proximal end of needle 32 and/or to distal connector 51. The interchangeable nature of suture 33 of the present invention permits a physician to select suture 33 on the basis of desired length, diameter, material, biocompatbility characteristics, biodegradability characteristics, and so on.

Examples of materials from which suture 33 may be formed or made include, but are not limited to, polydioxanone (PDS II), coated VICRYL RAPIDE (polyglactin 910), surgical gut suture, monocryl (poliglecaprone 25), polypropylene, NURULON braided nylon, PERMA-HAND silk, MERSILENE polyester fiber, ETHIBOND EXCEL polyester, surgical stainless steel, ETHILON nylon, and PROLENE polypropylene sutures.

It is preferred that suture 33 range between about 10 cm and about 20 cm in length, and have a diameter no larger than that of the electrode tip (e.g., less than or equal to about 0.6 mm). Additionally, it may be another feature of suture 33 of the present that suture 33 be formed or made of a material which is absorbable, resorbable, and/or biodegradable within the human body after lead 30 has been implanted. Such characteristics of suture 33 can eliminate the need for a physician to post-operatively perform surgery on a patient within whom lead 30 has been implanted for the purpose of retrieving suture 33 or portions thereof. The rate at which suture 33 degrades or decomposes within the patient can be controlled by appropriately selecting the material and/or physical dimensions from which suture 33 is made Examples of appropriate biodegradable, decomposable, absorbable and/or resorbable materials suitable for use in suture 33 of the present invention include, but are not limited to, polydioxanone (PDS II), VICRYL RAPIDE (polyglacbn 910), coated VICRYL RAPIDE (polyglactin 910), plain surgical gut suture, chromic surgical gut suture, and MONOCRYL (poliglecaprone 25) sutures.

FIG. 8(b) shows another embodiment of a medical electrical lead of the present invention having a replaceable or resorbable suture wire forming portions of the distal end thereof. In the embodiment illustrated in FIG. 8(b), distal connector 51 is a crimp connector, where the proximal end of suture wire 33 is crimped thereto. Other types of connectors 51 are contemplated in the present invention, such as welded connectors, swaged connectors, thermoset connectors, glued connectors, tied connectors, and connectors 51 shown in FIGS. 8(c) through 8(f), where set screw connector 51, one-way mechanically-biased “squeeze” connector 51, matingly engaging clamshell snap-on connector 51, and hinged matingly engaging clamshell connector 51, respectively, are illustrated. It will now become apparent that many different embodiments of connector 51 not shown explicitly in the drawings are possible, all falling within the scope of the claims directed to the present invention.

FIG. 9 shows one embodiment of a medical electrical lead of the present invention having a breakable or snappable needle attached to the distal end thereof. This particular embodiment of the present invention eliminates the requirement for separate temporary testing wire 19 shown in FIG. 2 hereof. Instead, needle 32 itself is employed in place of the temporary testing wire as a testing or temporary stimulating electrode. Once the physician has completed temporary testing activities, needle 32 is snapped or broken off at thinned or weakened section 53 thereof. See, for to example, U.S. Pat. No. 5,792,217 entitled “Temporary Bipolar Hear wire” to Camps et al. and U.S. Pat. No. 5,871,528 entitled “temporary Bipolar Hear Wire” to Camps et al., the disclosures of which are hereby incorporated by reference herein, each in its respective entirety, where various types of weakened zones suitable for use in section 53 hereof are disclosed. Suture is wire 33 may be attached to distal connector 51 using eyelet 53 or other suitable means.

Yet another desirable feature of the present invention when employed in intramuscular applications is that needle 32 possess a point which is blunt and not sharp. Such a blunt point does not pierce muscle tissue and instead splices such tissue, thereby resulting in less traumatic injury to the muscle issue. For example, ETHICON's ETHIGUARD Blunt Point Needle is desirably employed in conjunction with other components of the present invention, as are any one of ETHICON's ¼ circle, 3/18 circle, ½ curve, 1/2 circle, 5/8 circle and straight needles. Moreover, needle insertion force may be diminished by applying a slippery coating to needle 32 such as silicone rubber, PTFE, and other materials which become or remain slippery when wetted.

Because the connectors of the present invention are required to be in electrical contact with the electrical conductors of lead 30, the conductors are preferably attached to the distal ends of the connectors by a combination of compressing, inserting and crimping steps. Other methods of electrically conductive attachment such as brazing, soldering or welding may of course be utilized. The connectors of the present invention are not limited to pin connectors, but include any plurality of connectors having suitable configurations for attachment to the blunt end. The proximal ends of the connectors need not be removed from the needle by manual means only. Specially configured tools may be used to break or pull the connectors free of the needle.

Furthermore, the present invention is not limited to embodiments where all electrodes are attached to the same lead body, where one electrode must necessarily be disposed proximally or distally of the other electrode or electrodes, or where the electrodes are crimpingly attached to the conductors. For example, an electrode of the present invention may be formed by merely stripping away insulation overlying bare wire at a suitable location, by attaching a clip to bare wire, or by heat shrinking electrically conductive heat shrink over selected portions of bare wire.

The scope of the present invention is not limited to intramuscular electrical stimulation or sensing applications, but extends to neural, defibrillation, cardiac mapping, abdominal stimulation, and other medical and medical device applications and methods. Moreover, lead 30 of the present invention may be employed at numerous different muscle implant locations, and is not limited to use in cardiomyoplasty or graciloplasty applications. For example, lead 30 of the present invention may be employed in gluteus muscle implantation procedures to correct fecal or urinary incontinence, and may further be employed in rectal muscle implants in bladder myoplasty procedures. The scope of the present invention is not limited to applications where a human organ or plurality of organs is sensed monitored, paced, or defibrillated, but includes similar applications in animals.

The present invention also includes within its scope methods of making the leads, electrodes, and fixation members disclosed hereinabove. Although only a few exemplary embodiments of the present invention have been described in detail above, those skilled in the art will appreciate readily that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the following claims.

In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts a nail and a screw are equivalent structures.

All patents, patent applications and/or printed publications disclosed hereinabove are hereby incorporated into the specification hereof, each in its respective entirety.

Claims

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22. A method of selecting a location for and implanting a muscular lead, wherein the muscular lead comprises: a needle having a needle point; a test wire that is configured to supply current to needle; a lead that is connected to the needle comprising the steps of:

(a) placing the needle point in contact with at least one test location on the surface of a muscle;

(b) providing current to the needle point with the test wire;

(c) observing the response of the contacted muscle to the current from the needle point;

(d) selecting a location for implantation of the muscular lead;

(e) severing the test wire adjacent to its attachment point with the needle: and

(f) penetrating the selected muscle location with the needle to draw the lead into the muscle.

23. The method of claim 22, wherein steps (a)-(c) are carried out more than once.

24. The method of claim 22, wherein the current that is provided in step (b) is varied and the variable response of the contacted muscle is observed.

25. The method of claim 22, wherein step (d) is based at least in part on the amount of current provided in order to observe a response, the magnitude of the muscle response, or some combination thereof.

26. The method of claim 22, wherein the step (a) is accomplished by gripping a portion of the needle that is insulated.