U.S. patent application number 11/330051 was filed with the patent office on 2006-09-07 for medical lead and method for medical lead manufacture.
Invention is credited to Bradley J. Wessman.
Application Number | 20060200217 11/330051 |
Document ID | / |
Family ID | 24688828 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060200217 |
Kind Code |
A1 |
Wessman; Bradley J. |
September 7, 2006 |
Medical lead and method for medical lead manufacture
Abstract
A lead employing a connection between a conductor and an
electric element is provided. The connection includes a conductive
pad electrically connected to at least one conductor and the
electric element electrically connected to the conductive pad. The
conductive pad can further include an elongated element to connect
the pad to the electric element. The method for connecting a
conductor to an electric element is also provided. The method
includes forming a groove in the insulator of a lead body to expose
the conductor. Placing a conductive pad within the groove and
electrically connecting a conductive pad to the conductor. An
electric element is then placed over the conductive pad and the
electric element is electrically connected to the conductive
pad.
Inventors: |
Wessman; Bradley J.; (Maple
Grove, MN) |
Correspondence
Address: |
DOCKET CLERK, DM/ANSI
P.O. BOX 802432
DALLAS
TX
75380
US
|
Family ID: |
24688828 |
Appl. No.: |
11/330051 |
Filed: |
January 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09670062 |
Sep 26, 2000 |
7039470 |
|
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11330051 |
Jan 11, 2006 |
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Current U.S.
Class: |
607/116 |
Current CPC
Class: |
Y10T 29/49117 20150115;
A61N 1/05 20130101 |
Class at
Publication: |
607/116 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1.-29. (canceled)
30. A method for manufacturing a medical lead, the method
comprising: cutting a welding region in a lead body to expose a
conductor; securing a conductive pad within the welding region
adjacent the conductor; and securing a band to the conductive pad
to electrically connected the band to the conductor.
31. A method in accordance with claim 30 wherein the conductive pad
is secured within the welding region by a method selected from the
group consisting of welding, crimping and adhesives.
32. A method in accordance with claim 30 wherein the welding region
is in the shape of a groove.
33. A method in accordance with claim 32 wherein the groove is
formed obliquely across the lead body and parallel to the
conductor.
34. A method in accordance with claim 32 wherein the welding region
is formed using a laser.
35. A method in accordance with claim 34 wherein securing the band
further comprises welding the band to the conductive pad using a
laser.
36. A method of forming a medical lead, the method comprising:
forming using a laser a first welding region within insulating
material in a lead body to expose a first conductor; forming using
a laser a second welding region within the insulating material in
the lead body expose the first conductor; forming a first
conductive pad within the first welding region and electrically
connecting the first conductive pad to the first conductor; forming
a second conductive pad within the second welding region and
electrically connecting the first conductive pad to the first
conductor; electrically connecting a first electrode to the first
conductive pad; and electrically connecting the first electrode to
the second conductive pad.
37. A method in accordance with claim 36 wherein the first welding
region and the second welding region are in the shape of a
groove.
38. A method in accordance with claim 37 wherein the grooves are
formed obliquely across the lead body and parallel to the first
conductor.
39. A method in accordance with claim 34 wherein electrically
connecting the first electrode to the first conductive pad further
comprises welding the electrode to the first conductive pad, and
electrically connecting the first electrode to the second
conductive pad further comprises welding the electrode to the
second conductive pad.
40. A method in accordance with claim 36 wherein the first and
second conductive material each comprise a conductive metal
selected from the group consisting of stainless steel, MB35N,
Pt--Ir, platinum, silver, gold, copper and vanadium.
41. A method of forming a medical lead, the method comprising:
forming a welding region within insulating material in a lead body
of the medical lead to expose a conductor, the welding region
having a shape of a groove and formed obliquely across the lead
body and parallel to the conductor; placing a conductive pad within
the welding region and securing the conductive pad to the conductor
using a laser; and electrically connecting an electrode to the
conductive pad.
42. A method in accordance with claim 41 wherein the welding region
is formed using a laser.
43. A method in accordance with claim 42 wherein the conductive
material comprises a conductive metal selected from the group
consisting of stainless steel, MB35N, Pt--Ir, platinum, silver,
gold, copper and vanadium.
44. A method in accordance with claim 41 further comprising:
forming a second welding region within the insulating material to
expose the conductor, the second welding region having a shape of a
groove and formed obliquely across the lead body and parallel to
the conductor; placing a second conductive pad within the second
welding region and securing the second conductive pad to the
conductor using a laser; and electrically connecting the electrode
to the second conductive pad.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a medical leads and
particularly to a method of medical lead manufacture and medical
leads having a conductive pad connecting a band electrode to a
conductor.
[0003] 2. Description of the Related Art
[0004] Implantable leads form an electrical connection between a
pulse generator or other electronic device and a tissue or
structure in the body. For example, leads transmit electric signals
used to stimulate cardiac or nerve tissue in one direction and
signals generated by sensors placed in proximity to particular
organs or tissues in the opposite direction. Leads typically
include one or more electrodes at the lead's distal end. The
electrodes are designed to form an electrical connection with a
tissue or organ. Most leads also include a lead connector at the
lead's proximal end. Lead connectors are adapted to electrically
and mechanically connect leads to the pulse generators or other
electronic medical devices. A conductor connects the electrode to
the lead connector. Commonly, the conductor takes the form of a
single or multifilar wire coil. Although, there is an increasing
interest in using stranded cables as conductors. Regardless of the
conductor's form, an insulating material typically surrounds the
conductors. Spinal chord stimulation leads are typically formed
with individually insulated conductors surrounded by a separate
lead body tube. Together, the conductor and the insulating material
form the lead body. The lead body couples the lead connector at the
proximal end with the electrode at the distal end.
[0005] Manufacturing leads is costly. A significant portion of the
cost is allocated to electrically connecting the conductors to the
various electrodes, sensors and connectors used in the industry.
Forming a secure electrical junction has proven difficult and time
consuming. Laser welds are commonly used to connect the conductors
to the electrodes. The conductors are typically helically wound
into a coil for increased reliability and flexibility. Band
electrodes are typically connected to conductors by welding in an
operation separate from the application of the lead body tube. Once
the band electrodes are connected to the conductors, an extruded
tube is placed over the conductor coil and welded band electrodes
are connected to the lead body tube by insert molding or RF
welding. Band electrodes may also be connected to a conductor by
etching away a region of insulator, applying a coating of
electrically conductive adhesive, and then placing the band
electrode around the conductor. This etching method is complex, not
amenable to automation and expensive. Therefore, a need exists for
a method that reduces complexity and is easily automated to reduce
production costs.
[0006] In another method of attachment, band electrodes are
electrically connected to coiled conductors by placing a soft metal
in a hole cut into an insulating sleeve. An electrode is placed
over the metal and crimped or swaged to bring the electrode, soft
metal and coiled conductors into electrical contact and to secure
the electrode to the lead body. The crimping or swaging method of
connection results in electrical connections between the conductor
and the band electrode that may fail. Further, swaging to
electrically connect an electrode to a conductor is time consuming
and difficult to implement with the modern reduced diameter leads.
Hence, a need exists for an improved manufacturing technique to
secure band electrodes to conductors that reduces the time,
complexity and cost while increasing reliability.
[0007] In addition, current manufacturing techniques frequently
require adding elements, such as collars, when connecting a band
electrode to a coil. The added elements increase the lead's
diameter near the weld. In application, a uniform diameter weld
would result in a smaller lead. A smaller diameter lead is desired
to allow placement in restricted spaces such as the epidural space
or cardiac veins to reduce the effects of implanted lead on the
patient. Further, a smaller lead allows for a smaller introducer
that reduces the trauma associated with implantation and similarly
a smaller removal sheath when explanting the lead. Hence, there
exists a need to reduce the diameter of the welds used to secure
electrodes to conductors in implantable medical leads.
[0008] The present invention meets these needs and provides other
advantages and improvements that will be evident to those skilled
in the art.
SUMMARY OF THE INVENTION
[0009] The present invention provides a lead and method for lead
construction that reduces the time, complexity and costs of
producing implantable electrical leads by providing a novel
connection between the conductors and an electrode, connector or
sensor.
[0010] The medical lead includes a lead body, a conductive pad and
a band. The lead body is comprised of an insulator and at least one
conductor. The insulator includes at least one welding region
exposing at least one conductor. The welding region may be in the
form of a groove cut in the insulator. When in the form of a
groove, the welding region typically is cut parallel to the
orientation of the conductor. The conductive pad is secured within
the welding region to electrically connected to the conductor to
the pad. The conductive pad may be composed of stainless steel,
MP35N, platinum, gold, silver, copper, vanadium or other metal. The
conductive pad may be electrically connected to the conductor by
welding, conductive adhesives, crimping or other methods.
Alternative to the conductive pad, an elongated conductive element
may be used to electrically connected to the conductor to the pad.
The elongated conductive element can be a wire, a ribbon wire, a
cable, or other elongated form. The elongated conductive element
may be composed of stainless steel, MP35N, platinum, gold, silver,
copper, vanadium or other metal. The elongated conductive element
may be electrically connected to the conductor by welding,
conductive adhesives, crimping or other methods. The band is welded
to the conductive pad to electrically connect the band to the
conductor. The band may be a band electrode, a band connector, a
sensor, or other element electrically secured to medical leads. The
band may include a plurality of projections on an inner wall of a
lumen. The projections space the inner wall from an outer surface
of the lead body. Three or more projections may be positioned
around the inner wall to center the lead body within the lumen
during assembly.
[0011] The method for manufacturing a medical lead includes forming
a welding region, securing a conductive pad within the welding
region, and securing a band to the conductive pad. The welding
region is typically formed by cutting through the insulator to
expose the conductor. The welding region can cut with a laser,
typically an excimer laser, or can be mechanically cut. The
conductive pad is secured within the welding region adjacent the
conductor. The conductive pad can be secured within the welding
region using a weld, crimping conductive adhesives or other method.
The band is secured to the conductive pad to electrically connect
the band to the conductor. To secure the band, a weld is formed
between the conductive pad and the band. A yttrium-arsenic-garnet
laser may be used to form the weld.
[0012] Alternatively to the use of a conductive band, an elongated
conductive element may be substituted. The proximal end of the
elongated conductive element is secured conductor within the
welding region. The band is then positioned around the lead body
and over the welding region. The distal end of the elongated
conductive element is then electrically connected to the band. The
elongated conductive element may be electrically connected to the
band by welding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates a perspective view of a lead in
accordance with the present invention;
[0014] FIG. 2 illustrates a longitudinal cross-sectional view of a
of a lead showing an embodiment of the connection between a coiled
conductor and a band with a conductive pad;
[0015] FIG. 3 illustrates a top view of a lead, as shown in FIG. 2,
without the band;
[0016] FIG. 4 illustrates a longitudinal cross-sectional view of a
of a lead showing the connection between a coiled conductor and a
band with an elongated conductive element;
[0017] FIG. 5 illustrates a top view of a lead, as shown in FIG. 4,
without the band;
[0018] FIG. 6A illustrates a cross-sectional longitudinal view of a
band electrode, as shown in FIGS. 4 and 5; and
[0019] FIG. 6B illustrates and end view of the band electrode, as
in FIG. 6A.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention provides a medical lead and a method
for lead manufacture. The invention is described generally in the
context of an electrode for a neurostimulating lead and a method
for manufacturing a neurostimulating lead as a specific example for
illustrative purposes only. The appended claims are not intended to
be limited to any specific example or embodiment described in this
patent. It will be understood by those skilled in the art that
leads in accordance with the present invention may be used for a
wide variety of applications including, but not limited to, leads
and catheters for use with cardiac monitoring devices, cardiac
rhythm management devices, ablation devices, mapping devices,
neurostimulating devices, neuromonitoring devices or other medical
devices using leads or catheters. Further, in the drawings
described below, the reference numerals are generally repeated
where identical elements appear in more than one figure.
[0021] FIG. 1 illustrates an embodiment of a lead 10 made in
accordance with the present invention. Leads designed for
neurostimulation typically have two or more longitudinally spaced
band electrodes at the lead's distal end. Lead 10, as shown,
includes a lead body 12 and four band electrodes 14. Lead 10 is
generally configured to transmit an electric signal from a pulse
generator (not shown) to a spinal nerve or peripheral nerve. Thus,
electrodes 14 are typically located at the distal end of lead 10.
Lead body 12 includes a flexible lead insulator surrounding one or
more conductors. The conductors are electrically coupled to the
band electrodes. In addition, a lead connector 15 is typically
located at the proximal end of lead body 12 to electrically couple
the conductors to the pulse generator.
[0022] Typically, lead body 12 is a flexible, elastomeric structure
having a round cross-section. Alternatively, lead body's
cross-section could be any number of shapes appropriate for the
specific application. The figures and the following description
generally refer to round cross-sectional shape for lead bodies for
exemplary purposes. The lead insulator is generally configured to
insulate the conductors and to present a smooth biocompatible
external surface to body tissues. Thus, the lead insulator is
typically coextensive with the conductor or conductors. When a
plurality of conductors form a multipolar lead, individual
conductors are typically electrically isolated from one another.
The insulator material is typically selected based on
biocompatibility, biostability and durability for the particular
application. The insulator material may be silicone, polyurethane,
polyethylene, polyimide, polyvinylchloride, PTFE, ETFE, or other
materials known to those skilled in the art. Moreover, alloys and
blends of these materials may also be formulated to control the
relative flexibility, torqueability, and pushability of the lead.
Depending on the particular application, the diameter of the lead
body may be as small as 2 French or smaller for neurological and
myocardial mapping/ablation leads and can be sizes larger than 12
French for other applications.
[0023] The conductors may take the form of solid wires,
drawn-filled-tube (DFT), drawn-brazed-strand (DBS), stranded cables
or other forms that will be recognized by those skilled in the art.
The conductors may be composed of stainless steel, MP35N, or other
conductive materials known to those skilled in the art. The number,
size, and composition of the conductors will depend on particular
application for the lead.
[0024] At least one band electrode 14 is positioned at the distal
end of lead body 12 for electrically engaging a target tissue or
organ. In addition, at least one band connector 15 is positioned at
the proximal end of the lead body for electrically connecting the
conductors to the neurostimulator. For purposes of the present
invention, band electrodes 14 and band connectors 15 are
collectively referred to as bands. The bands are typically made of
a conductive material such as platinum, gold, silver,
platinum-iridium, stainless steel, MP35N or other conductive metals
or alloys thereof known to those skilled in the art. The bands are
typically composed of a material thin enough to allow for welding
of the elements to the underlying conductive pad, as discussed
below. For neurostimulation, band electrodes 14 are typically
between 1 and 10 millimeters long and have a diameter between about
2 and about 8 French but are more typically between 4 and 6 French.
Typically, band connectors 15 have a size and configuration
appropriate to connect the lead to a particular
neurostimulator.
[0025] FIG. 2 illustrates the details of an embodiment of the
connection between a conductor 22 and band electrode 14 in
accordance with the present invention. Band electrodes are the
point of electrical contact between the conductors and the patient.
Although discussed in the context of a band electrode, one skilled
in the art will recognize that the following description is also
applicable to a band connector, a sensor or other electrical
element. For exemplary purposes, band electrode 14 and lead body 12
is configured for two welds at a welding region 20. At least one
weld is typically utilized. In the particular embodiment, the same
conductor is connected to band electrode 14 twice. FIG. 2
illustrates a longitudinal cross-section of a lead body having four
spirally wound conductors for exemplary purposes. The lead body is
shown with four conductors. The conductors may be visible through
the insulating material when the insulating material is
translucent.
[0026] FIG. 3 illustrates a top view of a lead body having the
insulating material removed to form welding region 20 by exposing
conductor 22. Welding region 20 provides access to conductor(s) 22
for electrically connecting the band electrode to conductor 22.
Welding region 20 is typically formed by removing the insulating
material from lead body 10. The insulating material is removed to
expose small sections of the individual conductors 22 without
breaching an inner lumen, if present. Typically, an excimer laser
is used to remove the insulating material. When the insulator is
removed by laser, welding region 20 may be in the form of a groove
in the insulator. Although, welding region 20 may take a variety of
forms and orientations that expose a sufficient surface area of
conductor 22 to form an electrical connection with a conductive
pad, discussed below. When in the form of a groove, welding region
20 is typically formed such that the groove runs parallel to
conductor 22. Regardless of the form of welding region 20, enough
insulating material is removed to expose sufficient surface area of
conductor 22 for securing a conductive pad or elongated conductive
element to the conductor.
[0027] Referring to FIGS. 2 and 3, a conductive pad 24 is
positioned within welding region 20 during manufacture to
facilitate the electrical connection of band electrode 14 and
conductor 22. A weld 26 is typically used to secure the conductive
pad 24 in electrical contact with conductor 22. Alternatively,
conductive pad 24 may be secured using an adhesive. Conductive pad
22 may be composed of any of a variety of conductive materials that
can be welded or secured with adhesives. The metal may be stainless
steel, MP35N, Pt--Ir, platinum, silver, gold, copper, vanadium or
other metal that will be recognized by one skilled in the art upon
review of this disclosure. Conductive pad 24 is positioned within
welding region 20 so that conductive pad 24 is in electrical
contact with conductor 22. Typically, conductive pad 24 is welded
to the conductor prior to placing band electrode 14 over the
welding regions and conductive pads 24. A pulsed
Neodymium:yttrium-arsenic-garnet (YAG) laser may be used to weld
conductive pad 24 to conductor 22. FIG. 2 shows a side view of a
cross-section of two grooves 20 that expose two regions of the same
conductor 22. Conductive pads 24 are welded to conductor 22 within
grooves 20. Band electrode 14 is placed over lead body 12 of lead
10 and welded to conductive pads 24, thereby securing band
electrode 14 to lead body 12 and electrically connecting conductor
22 and band electrode 14. Band electrode 14 may be further secured
to lead body 12 by swaging, crimping and/or adhesives.
Alternatively, the band electrode may be secured to the lead body
by heating the lead body. Heating the lead body stress-relieves the
plastic increasing the outside diameter and securing the band
electrode over the lead body. In addition, heating the lead body
may be used to create a lead having a uniform diameter band and
lead body.
[0028] FIGS. 4 and 5 illustrate the details of another embodiment
of a connection between conductor 22 and a band connector 15 in
accordance with the present invention. Band connectors are the
point of electrical contact between the medical device using the
lead and the conductors within the lead. Although discussed in the
context of a band connector, one skilled in the art will recognize
that the following description is also applicable to band
electrodes, sensors or other electrical elements. An elongated
conductive element 34 is used to electrically connect the band to
conductor 22. The elongated conductive element may be in the form
of a wire, a ribbon wire, or a cable. The metal may be stainless
steel, MP35N, Pt--Ir, platinum, silver, gold, copper, vanadium or
other metal that will be recognized by one skilled in the art upon
review of this disclosure. A distal end of elongated conductive
element 34 is electrically connected to band connector 15.
Typically, the electrical connection employs a weld 28, although a
conductive adhesive or other method of conductively attaching may
be used. FIG. 4 shows a longitudinal cross-section of a lead body
having four spirally wound conductors. One or more welding regions
20 are formed through the insulating material by removing the
insulating material from lead body 10. Typically, the insulating
material is removed with a laser. The proximal end of elongated
conductive element 34 is positioned within welding region 20 so
that the proximal end is in electrical contact with conductor 22.
Typically, the proximal end is secured to conductor 22 prior to
placing band connector 15 over lead body 12. Again, the proximal
end is typically welded although a conductive adhesive or other
method of conductively attaching the proximal end may be used. The
elongated conductive element 34 and attached proximal end are
typically configured to allow band connector 15 to pass over
elongated conductive element 34 during assembly. The distal ends of
elongated conductive elements 34 may then be electrically connected
to band connector 15.
[0029] FIGS. 4 and 5 illustrate a single exemplary connection
between conductor 22 and band connector 15 by welds 26 and 28.
Thus, FIG. 4 shows only one groove 20 exposing conductor 22. The
proximal end of elongated conductive element 24 is positioned
within groove 20 is welded to conductor 22. Band connector 15 is
placed over lead body 12 and welded to elongated conductive element
34, thereby electrically connecting conductor 22 and band connector
15. Band connector 15 may be further secured to lead body 12 by
swaging, crimping, adhesives and/or insert molding. In addition,
swaging may reduce the outside diameter of lead connector 15 to
permit the manufacture of a lead of uniform diameter. Further, lead
body 12 may be expanded by heating to create a uniform diameter for
lead connector 15.
[0030] FIGS. 6A and 6B illustrate an embodiment of a band which may
be used in conjunction with the present invention. Although
discussed in the context of a band connector, one skilled in the
art will recognize that the following description is also
applicable to band electrodes, sensors or other electrical
elements. Band connector 15 includes an inner wall 42 defining a
lumen 44. At least one projection 46 is formed on the inner wall
42. Projections 46 define a space between inner wall 42 and an
outer surface of the lead body during assembly. Projections 46 may
be molded on the inner surface; formed by crimping the exterior
surface of the band; or added as separate elements secured to the
inner surface of the band. Projections 46 have a height 45 which
defines the amount of space between the outer surface of the lead
body and inner wall 42. Height 45 is generally selected to allow
conductive pads 24 and/or conductive elements 34 to pass beneath
the inner wall during assembly. Typically, three projections are
provided at positions around the circumference of band connector 15
to center band connector 15 over lead body 12 during assembly.
Centering band connector 15 so that height 45 is substantially the
same around the circumference of the lead body assures clearance of
the conductive element during assembly.
* * * * *