111111
`
`1111111111111111111111111111111111111111111111111111111111111111111111111111
`US 20030199950Al
`
`(19) United States
`(12) Patent Application Publication
`Stolz et al.
`
`(10) Pub. No.: US 2003/0199950 Al
`Oct. 23, 2003
`(43) Pub. Date:
`
`(54)
`
`IMPLANTABLE LEAD WITH ISOLATED
`CONTACT COUPLING
`
`(57)
`
`ABSTRACT
`
`(76)
`
`Inventors: Brian Stolz, Bloomington, MN (US);
`Mary Lee Cole, St. Paul, MN (US);
`Xavier E. Pardo, Minneapolis, MN
`(US)
`
`Correspondence Address:
`MEDTRONIC, INC.
`710 MEDTRONIC PARKWAY NE
`MS-LC340
`MINNEAPOLIS, MN 55432-5604 (US)
`
`(21) Appl. No.:
`
`10/128,883
`
`(22) Filed:
`
`Apr. 22, 2002
`
`Publication Classification
`
`Int. Cl? ....................................................... A61N 1/05
`(51)
`(52) U.S. Cl.
`............................................ 607/117; 600/377
`
`An implantable lead for a medical device with an isolated
`contact connection for connecting a conductor to a contact
`reduces the opportunity for conductor material to migrate to
`a contact or into a patient. The implantable lead comprises
`a lead body having a proximal end and a distal end, at least
`one conductor, at least one contact carried on the proximal
`end, at least one contact carried on the distal end, at least one
`coupling. The lead has an exterior surface. The conductor is
`contained in the lead body and extends from the lead
`proximal end to the distal end. The conductor is electrically
`insulated. The contact carried on the proximal end is elec(cid:173)
`trically connected to the conductor. The coupling has a
`conductor coupling and a contact coupling. The conductor
`coupling is placed over the conductor and attached to the
`conductor. The contact coupling exits the lead body and has
`a weld to connect the contact coupling to the contact. There
`is an isolation space created between the conductor and the
`contact to prevent the weld from containing conductor
`material.
`
`38
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`36
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`300
`
`36
`
`46
`
`Nevro Corp.
`Ex. 1005
`U.S. Patent No. 7,891,085
`
`

`

`Patent Application Publication Oct. 23, 2003 Sheet 1 of 11
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`US 2003/0199950 Al
`
`Oct. 23, 2003
`
`1
`
`IMPLANTABLE LEAD WITH ISOLATED
`CONTACT COUPLING
`
`CROSS REFERENCES
`
`[0001] This application is related to the following co(cid:173)
`pending applications entitled "Implantable Lead With
`Improved Conductor Lumens" by Pardo et al. (attorney
`docket no. P10706.00); "Implantable Lead With Improved
`Stylet Lumen" by Pardo et al. (attorney docket no.
`P10707.00); "Implantable Lead With Improved Distal Tip"
`by Stolz et al. (attorney docket no. P10708.00); "Improved
`Stylet For An Implantable Lead" by Pardo et al. (attorney
`docket no. P10709.00); and, "Implantable Lead With Copla(cid:173)
`nar Contact Coupling" by Cole et al. (attorney docket no.
`P10748.00), which are not admitted as prior art with respect
`to this application by its mention in this cross reference
`section.
`
`BACKGROUND OF THE INVENTION
`
`[0002] This disclosure relates to medical devices and more
`particularly to an implantable lead.
`
`[0003] The medical device industry produces a wide vari(cid:173)
`ety of electronic and mechanical devices for treating patient
`medical conditions such as pacemakers, defibrillators,
`neuro-stimulators and
`therapeutic
`substance delivery
`pumps. Medical devices can be configured to be surgically
`implanted or connected externally to the patient receiving
`treatment. Clinicians use medical devices alone or in com(cid:173)
`bination with therapeutic substance therapies and surgery to
`treat patient medical conditions. For some medical condi(cid:173)
`tions, medical devices provide the best and sometimes the
`only therapy to restore an individual to a more healthful
`condition and a fuller life. One type of medical device is an
`implantable neurological stimulation system that can be
`used to treat conditions such as pain, movement disorders,
`pelvic floor disorders, gastroparesis, and a wide variety of
`other medical conditions. The neurostimulation system typi(cid:173)
`cally includes a neurostimulator, a stimulation lead, and an
`extension such as shown in Medtronic, Inc. brochure
`"Implantable Neurostimulation System" (1998). More spe(cid:173)
`cifically, the neurostimulator system can be an Itrel II®
`Model 7424 or an Itrel 3® Model 7425 available from
`Medtronic, Inc. in Minneapolis, Minn. that can be used to
`treat conditions such as pain, movement disorders and pelvic
`floor disorders. The neurostimulator is typically connected
`to a stimulation lead that has one or more electrodes to
`deliver electrical stimulation to a specific location in the
`patient's body.
`
`Implantable leads have conductors that are con(cid:173)
`[0004]
`nected to contacts to form electrical paths. The connection
`between the conductors and the contacts should have a solid
`mechanical connection and a low impedance electrical con(cid:173)
`nection for efficient operation and reliability. Conductors
`manufactured from low impedance materials such as silver
`make forming a connection with good mechanical properties
`challenging because silver has substantially less tensile
`strength than a more common conductor material such as
`MP35N. Additionally, silver content in the weld joint
`between a conductor and contact increases the chances of
`separation, silver exposure to tissue, and weld corrosion
`during lead operation. Some previous connections directly
`connect the conductor to the contact but sometimes the
`
`conductor material is not ideal for forming a strong
`mechanical connection. Additionally, conductor material
`such as conductor ions can migrate from the conductor to the
`contact or even from the conductor into the patient. Other
`previous connections use a tube crimped to the conductor
`that is welded to the contact. Although the tube can improve
`the mechanical connection, material from the conductor can
`still migrate from the conductor to the contact or into the
`patient. An example of a lead with a joined conductor and
`electrode is shown in U.S. Pat. No. 6,181,971 "Joining
`Conductor Cables And Electrodes On A Multi-Lumen Lead
`Body" by Doan (Jan. 30, 2001).
`
`[0005] For the foregoing reasons, there is a need for an
`implantable lead with isolated contact couplings to reduce
`the opportunity for conductor material to migrate to the
`contact or into the patient.
`
`BRIEF SUMMARY OF THE INVENTION
`
`[0006] An implantable lead with an isolated contact con(cid:173)
`nection for connecting a conductor to a contact reduces the
`opportunity for conductor material to migrate to a contact or
`into a patient. The implantable lead comprises a lead body
`having a proximal end and a distal end, at least one con(cid:173)
`ductor, at least one contact carried on the proximal end, at
`least one contact carried on the distal end, at least one
`coupling. The lead has an exterior surface. The conductor is
`contained in the lead body and extends from the lead
`proximal end to the distal end. The conductor is electrically
`insulated. The contact carried on the proximal end is elec(cid:173)
`trically connected to the conductor, and the contact carried
`on the distal end is also electrically connected to the con(cid:173)
`ductor. The coupling has a conductor coupling and a contact
`coupling. The conductor coupling is placed over the con(cid:173)
`ductor and attached to the conductor. The contact coupling
`exits the lead body and has a weld to connect the contact
`coupling to the contact. There is an isolation space created
`between the conductor and the contact to prevent the weld
`from containing conductor material.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0007] FIG. 1 shows a general environmental view for a
`neurostimulation system embodiment;
`
`[0008] FIG. 2 shows a neurostimulation system embodi(cid:173)
`ment;
`
`[0009] FIG. 3 shows an implantable lead embodiment;
`
`[0010] FIG. 4 shows an implantable lead with cross(cid:173)
`section indication embodiment;
`
`[0011] FIG. 5 shows a cross section of the implantable
`lead embodiment shown in FIG. 4;
`
`[0012] FIG. 6 shows an implantable lead with proximal
`end enlargement indication embodiment;
`
`[0013] FIG. 7 shows an enlarged cross section of the
`proximal end shown in FIG. 6;
`
`[0014] FIG. 8 shows an implantable lead with distal end
`enlargement indication embodiment;
`
`[0015] FIG. 9 shows an enlarged cross section of the distal
`end shown in FIG. 8 embodiment;
`
`

`

`US 2003/0199950 Al
`
`Oct. 23, 2003
`
`2
`
`[0016] FIG. 10 shows a stylet with distal end enlargement
`indication embodiment;
`
`[0017] FIG. 11 shows the enlarged distal end shown in
`FIG. 10 embodiment;
`
`[0018] FIG. 12 shows an implantable lead with enlarge(cid:173)
`ment indication of a contact embodiment;
`
`[0019] FIG. 13 shows a cross section of the enlarged
`contact embodiment;
`
`[0020] FIG. 14 shows an isometric view of a contact and
`coupling embodiment;
`
`[0021] FIG. 15 shows an isometric view of the coupling
`embodiment shown in FIG. 14;
`
`[0022] FIG. 16 shows a flow chart of a method for
`creating an isolation space in an implantable lead contact
`connection embodiment; and,
`
`[0023] FIG. 17 shows a flow chart of a method for
`creating a coplanar connection in an implantable lead
`between a conductor and a contact embodiment.
`
`DETAILED DESCRIPTION OF 1HE
`PREFERRED EMBODIMENTS
`
`[0024] FIG. 1 shows a general environmental view of an
`implantable neurostimulation system embodiment and FIG.
`2 shows a neurostimulation system embodiment. Neuro(cid:173)
`stimulation systems are used to treat conditions such as pain,
`movement disorders, pelvic floor disorders, gastroparesis,
`and a wide variety of other medical conditions. The neuro(cid:173)
`stimulation system 20 includes a neurostimulator 22 such as
`an Itrel II® Model 7424 or an Itrel3® Model 7425 available
`from Medtronic, Inc. in Minneapolis, Minn., a stimulation
`lead extension 24, and a stimulation lead 30. The neuro(cid:173)
`stimulator 22 is typically implanted subcutaneously in the
`patient's body 18 at a location selected by the clinician. The
`stimulation lead 30 is typically fixed in place near the
`location selected by the clinician using a device such as the
`adjustable anchor. The implantable lead 30 can be config(cid:173)
`ured as a neurological stimulation lead, a neurological
`sensing lead, and a combination of both as a neurological
`stimulation and sensing lead, a cardiac lead, and the like.
`
`[0025] FIG. 3 shows an implantable lead embodiment. An
`implantable lead comprises a lead body 32, at least one
`conductor 34, at least two contacts 36. The lead body has a
`proximal end 38, a distal end 40, and an exterior surface 44.
`The lead body 32 can be composed of a wide variety of
`electrically isolative materials and configurations. Materials
`may include, but are not limited to, silicone rubber, poly(cid:173)
`urethane, fluoropolymers and the like. Configurations could
`include monolumen and multilumen lead bodies. The exte(cid:173)
`rior surface 44 is composed of one or more biocompatible
`materials.
`
`[0026] The conductor 34 is contained in the lead body and
`generally extends from the lead proximal end 38 to the distal
`end 40. The conductors 34 can be manufactured from a wide
`range of materials that are electrically conductive such as
`MP35N, platinum and the like. In some embodiments, the
`conductor 34 can comprise a plurality of wires that can be
`configured as braided strand wire (BSW). BSW is available
`in many configurations including seven wire BSW. When
`low impedance is desired, the core of each wire can be
`
`manufactured from a low impedance metal such as silver
`and the jacket can be manufactured from a material with
`good mechanical strength properties such as MP35N. One
`embodiment of conductor 34 uses seven wire BSW with a
`silver core and an MP35N jacket typically with a resistance
`of less than about 0.098 ohms/em (3 ohms/foot) and a tensile
`strength greater than 5N. The conductor 34 can be electri(cid:173)
`cally insulated with a flouro-polymer such as ethyletetraf(cid:173)
`louroethylene with a coating thickness of approximately
`0.0002 em (0.0008 inch).
`
`[0027] The contacts 36 includes at least one contact 36
`carried on the lead distal end 40 that is electrically connected
`to the conductor 34 and at least one contact 36 carried on the
`proximal end 38 that is electrically connected to the con(cid:173)
`ductor 34. The proximal contacts are typically manufactured
`from a material with good mechanical strength and biocom(cid:173)
`patible properties such as MP35N and the like to withstand
`interaction with mating devices such as an implantable
`neurological extension. The distal contacts are typically
`manufactured from materials with good electrical and bio(cid:173)
`compatibility properties such as platinum and iridium alloys
`that can be configured in a mixture such as 90% platinum
`and 10% iridium. In some embodiments, spacers 46 are
`inserted between contacts 36 so the proximal end 38 and
`distal end 40 are substantially iso-diametric.
`
`[0028] FIG. 4 shows an implantable lead embodiment,
`and FIG. 5 shows a cross section of the implantable lead in
`FIG. 4. An implantable lead with improved conductor
`lumens comprises a lead body 32, a stylet lumen 100, at least
`one conductor lumen 102, and at least one axial slit 42. The
`lead body has an internal portion 104 and an external portion
`106. The stylet lumen 100 and the conductor lumen 102 are
`formed in the internal portion 104. The internal portion 104
`is a continuous material that has a proximal end 38, distal
`end 40 and an outer surface that is encapsulated by the
`external portion 104. This structure can be extruded and its
`configuration can be substantially the same at any longitu(cid:173)
`dinal cross section. The internal portion 104 has an outside
`diameter smaller than the inside diameter of the external
`portion 106. In some embodiments, the internal portion 104
`outside diameter is approximately 0.102 em (0.04 inch)
`smaller than the external portion 104 inside diameter. The
`internal portion 104 is fitted inside of the external portion
`106. The external portion 106 exterior surface 44 typically
`has an outer diameter selected for the therapeutic application
`such as in the range from about 0.05 em (0.02 inch) to about
`0.20 em (0.08 inch) with one embodiment having an outer
`diameter of about 0.127 em (0.05 inch). The stylet lumen
`100 is formed in the internal portion 104 typically in the
`center and sized to provide clearance between the stylet
`lumen 100 and the coaxially inserted stylet wire 404 in the
`range from about 0.00025 em (0.0001 inch) to about 0.025
`em (0.01 inch), and in some embodiments that clearance is
`about 0.0038 em (0.0015 inches).
`
`[0029] The conductor lumen 102 is formed in the internal
`portion 104 and positioned near an outer surface of the
`internal portion 104 such that there is only a web 110
`between the conductor lumen 102 and the outer surface of
`the internal portion 104. Some embodiments have a plurality
`of conductor lumens 102 such as in the range from about two
`to sixteen conductor lumens 102. The implantable lead
`embodiment shown has four conductor assembly lumens
`that are substantially equidistant from each other and to the
`
`

`

`US 2003/0199950 Al
`
`Oct. 23, 2003
`
`3
`
`centrally localized stylet lumen. The conductor lumens 102
`and stylet lumen 100 geometry provides axial stability, and
`the centrally located stylet lumen 100 improves navigation.
`Each conductor lumen 102 can be configured to resemble a
`polygon that is not necessarily symmetrical, and each con(cid:173)
`ductor lumen 102 has a diameter typically greater than about
`0.0254 em (0.01 inch). In some embodiments, the conductor
`lumens 102 electrically insulate each conductor 34 and
`physically separate each conductors 34 to facilitate identi(cid:173)
`fication of the conductor 34 that is appropriate for its single
`corresponding contact 36. The film 108 thickness between
`the conductor lumens 102 and the stylet lumen 100 is no less
`than about 0.00254 em (0.001 inch). This film 108 is flexible
`enough to allow the entering stylet to slide through the lead
`body without penetrating through into a conductor lumen
`102 or out of the lead body.
`[0030] The web 110 allows an axial slit 42 to be created in
`the internal portion 104 distal end for a path to exist between
`the conductor lumen 102 and the internal portion 104 outer
`surface. The web 110 is no greater than 0.005 em (0.002
`inch) thick. The web 110 provides the means for a conductor
`lumen 102 formed inside the lead body to be positioned near
`the exterior surface 44 of the lead body. The axial slit 42 is
`formed in the internal portion 104 distal end between the
`conductor lumen 102 and the outer surface of the internal
`portion 104. The axial slit 42 provides a temporary opening
`for a coupling 112 (FIG. 9) to exit the conductor lumen 102
`and attach to a contact 36. The axial slit 42, when stretched
`ajar, opens to a width of at least about 0.01 em (0.0039 inch)
`to allow the coupling 112 to exit the conductor lumen 102.
`Once the coupling 112 is connected to the contact 36, the
`axial slit 42 preferably seals back.
`
`[0031] FIG. 6 shows an implantable lead with proximal
`end 38 enlargement indication embodiment, and FIG. 7
`shows an enlarged cross section of the proximal end 38
`shown in FIG. 6. An implantable lead with improved stylet
`lumen comprises a lead body, at least two conductors 34,
`contacts 36, and a proximal flare 200. The lead body has a
`proximal end 38, a distal end 40, a stylet lumen 100, and at
`least two conductor lumens 102. The conductors 34 are
`contained in the conductor lumens 102 extending from the
`lead proximal end 38 to the distal end 40. The contacts 36
`are carried on the distal end 40 and electrically connected to
`the conductors 34. Typically, conductors 34 are also carried
`on the proximal end 38 and electrically connected to the
`conductors 34.
`
`[0032] The proximal flare 200 is formed on the lead body
`proximal end 38 and it has tapering walls that narrow toward
`a stylet opening to guide insertion of a stylet (FIG. 10) into
`the stylet lumen 100, and the proximal flare 200 seals the
`conductor lumens 102 proximal end to isolate the conductor
`lumens 102. The proximal flare 200 is manufactured for a
`non-rigid material typically similar to the lead body mate(cid:173)
`rial. The tapering walls have a slope typically in the range
`from about 0.25 em/em to about 0.50 em/em. The axial
`length of the flare 200 is no greater than about 0.064 em
`(0.025 inches). The wall thickness of the flare 200 ranges
`from 0.01 em (0.004 inch), at the most proximal end, to 0.05
`em (0.019 inch), at the distal end of the flare 200. The
`proximal flare 200 is flexible to reduce stylet deformation
`during insertion or withdrawal of the stylet. During stylet
`insertion into the stylet lumen 100, navigation, and with(cid:173)
`draw, the tapered walls absorb energy and stretch to accom-
`
`modate movement of the stylet to reduce stylet deformation.
`Also during stylet insertion into the stylet lumen 100, the
`proximal flare 200 substantially prevents the stylet from
`entering the conductor lumens 102. The flare 200 provides
`a progressive tactile feedback to indicate to the clinician the
`amount of of stylet pressure being applying to the lead
`proximal end 38 which reduces lead/stylet damage or defor(cid:173)
`mation during implant.
`[0033] The proximal flare 200 seals the conductor lumens
`102 proximal end to isolate the conductor lumens 102. The
`forming of the flare 200 places material in the conductor
`lumens 102 that typically extends no farther than the begin(cid:173)
`ning of the conductors 34 located within the conductor
`lumens 102. Sealing the conductor lumens 102 minimize
`electrical conductance between the conductors 34, fluid
`migration into the lumens or other attached neurological
`devices, and unwanted stylet introduction into the conductor
`lumens 102. The proximal flare 200 is manufactured from a
`non-rigid material that can be the same material as the lead
`body. The flare 200 can be formed by inserting the proximal
`end 38 of the lead body into a mold that has a conical shape.
`This conical shape is inserted axially into the center stylet
`lumen 100. Heat is transferred from the conical mold to the
`polyurethane internal portion 104 that seals the outer lumens
`and creates the flare 200.
`[0034] FIG. 8 shows an implantable lead with distal end
`40 enlargement indication embodiment, and FIG. 9 shows
`an enlarged cross section of the distal end 40 shown in FIG.
`8. An implantable lead with an improved distal tip 300
`comprises a lead body, at least two conductors 34, contacts
`36, a stylet lumen 100, conductor lumens 102, and a distal
`tip 300. The lead body has a proximal end 38, a distal end
`40, a stylet lumen 100, and at least two conductor lumens
`102. The at least two conductors 34 contained in the
`conductor lumens 102 extending from the lead proximal end
`38 to the distal end 40. The at least two contacts 36 carried
`on the proximal end 38 are electrically connected to the
`conductors 34. The at least two contacts 36 carried on the
`lead distal end 40 are also electrically connected to the
`conductors 34.
`[0035] The formed distal tip 300 seals the conductor
`lumens 102 free from adhesive or solvents. The conductor
`lumens 102 closed off by the formed distal tip 300 improve
`electrical isolation between the conductors 34. The formed
`distal tip 300 penetrates the lumens 100, 102 of the lead
`body. The material filling reaches no further into the lumens
`than making contact to the enclosed conductors 34.
`[0036] The distal tip 300 can be formed from the lead body
`by inserting into a mold; this mold has the shape of the
`desired distal tip 300. The distal tip 300 has a diameter
`approximately equal to the lead final diameter of appro xi(cid:173)
`mately 0.127 em (0.05 inch). The heat conducted from the
`mold to the lead distal tip 300, melts the surrounding
`material into the conductor lumen 102 and into the stylet
`lumen 100, completely sealing them from the outside.
`Sufficient material is left between the lumens 100, 102 to the
`outside of the lead such that substantial force would be
`needed to perforate, if at all, through the finally formed distal
`tip 300. The formed distal tip 300 is of the same material of
`the lead body and significantly minimizes the possibility of
`separation from the lead body.
`[0037] The distal tip 300 is substantially symmetrical
`since there is no need to align a separate distal tip 300. The
`
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`US 2003/0199950 Al
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`Oct. 23, 2003
`
`4
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`distal tip 300 is symmetrically formed such that it is coaxial
`with the lead body. Symmetry is desirable for minimized
`protuberances from the exterior lead surface 44, thus reduc(cid:173)
`ing the potential of lead body ruptures. The symmetrical
`formation of the distal tip 300 also reduces physical and
`material discontinuities in the distal tip 300 to improve the
`navigational sensitivity of the lead 30 during implant poten(cid:173)
`tially reducing operating room time.
`[0038] The distal tip 300 is a more robust stylet stop which
`reduces the opportunity for stylet penetration of the lead
`body distal end 40. The material penetrates the most distal
`end of the stylet lumen 100 by about 0.15 em (0.059 inch)
`into the stylet lumen 100 of the lead beginning from the most
`distal end of the hemi-spherical distal tip 300. The force
`transfer required for perforation of the lead distal end 40 is
`significantly increased, therefore, reducing any potential of
`tissue damage due to an exiting stylet and reducing the
`potential of creating an opening in the lead which may
`disable electrical properties of the device.
`[0039] FIG. 10 shows a stylet with stylet distal end 400
`enlargement indication embodiment, and FIG. 11 shows the
`enlarged distal end shown in FIG. 10. An implantable lead
`with an improved stylet comprises a lead body, a stylet
`lumen 100, at least one conductor 34, contacts 36, and a
`stylet. The lead body has a proximal end 38, a distal end 40,
`an exterior surface 44, and a stylet lumen 100 contained
`inside the lead body. The conductor 34 is contained in the
`lead body and generally extends from the lead proximal end
`38 to the distal end 40. The conductor 34 is electrically
`insulated by the lead body. There is at least one contact 36
`carried on the lead proximal end 38 that is electrically
`connected to the conductor 34, and there is at least one
`contact 36 carried on the lead distal end 40 that is electrically
`connected to the conductor 34.
`[0040] The stylet is composed of a stylet handle 402 that
`attaches to the proximal end 38 of the lead and a stylet wire
`404. The stylet wire 404 is configured for insertion into the
`stylet lumen 100 with a straight portion 406, a curved
`portion 408, and a ball tip 410 on the stylet distal end 400.
`The straight portion of the lead has a diameter of about
`0.0254 em (0.01 inch) and has a parylene insulation of about
`1.0 micron. The electrical insulation also serves as a coating
`that has a lower coefficient of friction than the stainless steel
`of the stylet wire 404.
`
`[0041] The curved portion of the stylet wire 404 has an
`angle, between the tangent of the curved portion and the
`straight portion that increases as the curve approaches the
`stylet distal end 400. The curved portion begins at about less
`than 3.75 em (1.48 inches) from the stylet distal end 400 of
`the stylet wire 404. The most distal angle of the curved
`portion has an angle greater than about 15 degrees from the
`straight portion.
`
`[0042] The tangent of the curve with respect to the straight
`portion of stylet increases linearly as the curve approaches
`the stylet distal end 400. Once fully inserted into the lead,
`the stylet/lead results in a distal end angle that allows the
`physician to manipulate the device into the desired location
`over the epidural space. The continuous and incremental
`curve of the lead distal tip 300 aids the physician to guide the
`lead past anatomical obstructions, that would otherwise,
`hinder the ease of introduction of the lead to its designated
`location for stimulation.
`
`[0043] The ball tip 410 is spherical and has a diameter that
`is greater than the stylet diameter and is no greater than the
`stylet lumen 100 inner diameter. The ball tip 410 is config(cid:173)
`ured to ease insertion of the stylet wire 404 through the stylet
`lumen 100 to the stylet distal end 400.
`
`[0044] The ball tip 410 functions by stretching the lumen
`where the stylet wire 404 is inserted to ease insertion of the
`remaining portion of the stylet wire 404. In addition, the ball
`tip 410 reduces abrasion to the stylet lumen 100 to reduce
`the risk of the stylet wire 404 protruding into the adjacent
`conductor lumens 102 or out of the exterior surface 44 of the
`lead body.
`
`[0045] FIG. 12 shows an implantable lead with contact 36
`enlargement indication, and FIG. 13 shows a cross section
`of an enlarged contact 36 embodiment. The coupling 112 has
`a conductor coupling 500 and a contact coupling 502. The
`conductor coupling 500 and the contact coupling 502 are
`manufactured from a material with good mechanical and
`electrical properties such as MP35N and the like. The
`conductor coupling 500 is placed over the conductor 34 and
`attached to the conductor 34 mechanically. The contact
`coupling 502 exits the lead body and has a weld 504 to
`connect the contact coupling 502 to the contact 36. The weld
`504, such as a laser weld, can be performed substantially on
`the contact 36 exterior surface 44 for ease of manufacturing.
`The weld 504 is performed such that the weld 504 pool is
`typically contained within the contact 36 perimeter. In
`addition, the weld 504 height is controlled to be less than
`about 0.0127 em (0.005 inch), so interaction with other
`devices is facilitated. Each contact 36 has a contact slot 508
`opening that in some embodiment is in the range from about
`0.0127 em (0.005 inch) to about 0.0381 em (0.015 inch) in
`width and at least about 0.0508 em (0.020 inch) in length. In
`other embodiments, the contact slot 508 can extend the
`entire length of the contact 36.
`
`[0046] An isolation space 506 is created between the
`conductor 34 and the contact 36 to prevent directly welding
`the conductor 34 to the contact 36. The isolation space 506
`separates the conductor 34 from the weld 504 to substan(cid:173)
`tially prevent the conductor 34 from contacting the weld
`504. The isolation space 506 is necessary since silver is not
`wanted in the weld 504 pool because silver potentially
`weakens the strength and integrity of a weld 504. In addi(cid:173)
`tion, it is desirable to avoid having silver contact the outside
`surface of the lead to avoid any direct contact with tissue.
`Although silver contact with tissue is not considered harm(cid:173)
`ful, the separation serves as an additional precaution. The
`isolation space 506 is greater than about 0.05 em (0.02 inch).
`The isolation space 506 serves as a means for isolation
`created between the conductor 34 and the contact 36 to
`prevent directly welding the conductor 34 to the contact 36.
`In some embodiments, the isolation space can include a fill
`material such as epoxy.
`
`[0047] FIG. 14 shows an isometric view of a contact 36
`and coupling 112 embodiment, and FIG. 15 shows an
`isometric view of the coupling 112 embodiment shown in
`FIG. 14. In this embodiment, the isolation space 506 is
`provided by the specific geometry of the contact coupling
`502 and more specifically the non-welded material between
`the conductor 34 and the weld 504 to the contact 36. The
`non-welded material is sized appropriately for the dimen(cid:173)
`sions of the lead such as greater than about 0.005 em (0.002
`
`

`

`US 2003/0199950 Al
`
`Oct. 23, 2003
`
`5
`
`inches). In this embodiment, the interface between the outer
`surface of the contact 36 and the other surface of the
`coupling 500 can be continuously welded along selected
`sides of the interface or intermittently welded along the
`interface.
`
`[0048] FIG. 16 shows a flow chart of a method for
`creating an isolation space 506 in an implantable lead
`contact connection embodiment. The method for creati