U.S. patent application number 13/549087 was filed with the patent office on 2013-06-20 for method for manufacturing an active fixation electrode.
This patent application is currently assigned to ST. JUDE MEDICAL AB. The applicant listed for this patent is Mikael Forslund, Marie Herstedt, Rolf Hill, Susanne Nilsson, Olof Stegfeldt, Anna Norlin Weissenrieder. Invention is credited to Mikael Forslund, Marie Herstedt, Rolf Hill, Susanne Nilsson, Olof Stegfeldt, Anna Norlin Weissenrieder.
Application Number | 20130156933 13/549087 |
Document ID | / |
Family ID | 39674294 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130156933 |
Kind Code |
A1 |
Weissenrieder; Anna Norlin ;
et al. |
June 20, 2013 |
METHOD FOR MANUFACTURING AN ACTIVE FIXATION ELECTRODE
Abstract
The present invention relates to methods for manufacturing
active fixation helices for the stimulation and/or sensing of
organs. A first embodiment of a method in accordance with the
present invention for making a helix comprises a first step of
producing an elongated helix precursor body comprising one or more
electrical conductors surrounded by an insulating material. This
helix precursor body is then shaped into a helix, material removed
in predetermined places in order to expose the areas of the
conductors which will be used as electrodes in the final product.
The body is coated with an electrically conducting biocompatible
coating which is subsequently partly removed in continuous loops
from around the electrodes in order to electrically insulate them
from each other and to ensure that the electrically active areas of
the electrodes are of the correct dimensions.
Inventors: |
Weissenrieder; Anna Norlin;
(Lidingo, SE) ; Hill; Rolf; (Jarfalla, SE)
; Stegfeldt; Olof; (Alta, SE) ; Herstedt;
Marie; (Uppsala, SE) ; Forslund; Mikael;
(Bromma, SE) ; Nilsson; Susanne; (Huddinge,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Weissenrieder; Anna Norlin
Hill; Rolf
Stegfeldt; Olof
Herstedt; Marie
Forslund; Mikael
Nilsson; Susanne |
Lidingo
Jarfalla
Alta
Uppsala
Bromma
Huddinge |
|
SE
SE
SE
SE
SE
SE |
|
|
Assignee: |
ST. JUDE MEDICAL AB
Jarfalla
SE
|
Family ID: |
39674294 |
Appl. No.: |
13/549087 |
Filed: |
July 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12522001 |
Jul 2, 2009 |
8250753 |
|
|
PCT/SE2007/000084 |
Jan 31, 2007 |
|
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|
13549087 |
|
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Current U.S.
Class: |
427/2.1 |
Current CPC
Class: |
Y10T 29/49218 20150115;
A61N 1/0573 20130101; Y10T 29/49201 20150115; Y10T 29/49174
20150115; H01B 13/00 20130101; Y10T 29/49073 20150115; Y10T
29/49169 20150115; Y10T 29/49124 20150115 |
Class at
Publication: |
427/2.1 |
International
Class: |
H01B 13/00 20060101
H01B013/00 |
Claims
1. A method of fabricating an electrically active helix for an
electrical medical lead comprising: a) forming a helix body having
a proximal end and a distal end connected by a plurality of helical
revolutions, the helix body comprising at least one electrically
conducting core partially surrounded by an insulating sheath,
wherein a portion of a surface of each electrically conducting core
extending from the distal end towards the proximal end and facing
in a predetermined direction is exposed; b) applying a continuous
electrically conducting, biocompatible coating to a surface of the
insulating sheath and each exposed surface of each electrically
conducting core; and c) removing a portion of the electrically
conducting biocompatible coating on the insulating sheath
surrounding each continuous portion of the surface of each
electrically conducting core such that the electrically conducting
coating on the exposed surface of each electrically conducting core
is not in electrical contact with the remaining electrically
conducting coating on the insulating sheath.
2. The method of claim 1, wherein step a) comprises: i) forming an
elongated helix body precursor having a proximal end and a distal
end, the helix body precursor comprising at least one electrically
conducting core and a surrounding insulating sheath in which there
is at least one longitudinally extending slit in the insulating
sheath which exposes a portion of each electrically conducting
core; and ii) forming the elongated helix body precursor in a helix
body in which a plurality of helical revolutions are formed between
the proximal end and the distal end of the helix body precursor,
and wherein the exposed surface of each electrically conducting
core faces in a predetermined direction.
3. The method of claim 2, wherein step i) comprises the step of
forming at least one electrically conducting core surrounded by an
insulating sheath which leaves at least one portion of each
electrically conducting core exposed.
4. The method of claim 2 wherein, in step c) the removal of the
portion of electrically conducting biocompatible coating is
achieved by polishing or cutting or grinding or a combination
thereof.
5. The method of claim 1, wherein the biocompatible coating is TiN
or TiSiC or platinum black or a metal oxide or other electrically
conducting material.
Description
FIELD OF THE INVENTION
[0001] This application is a division of U.S. patent application
Ser. No. 12/522,001, filed Jul. 2, 2009, which claims priority from
International App. No. PCT/SE2007/000084, filed Jan. 31, 2007.
FIELD OF THE INVENTION
[0002] The present invention relates to methods for manufacturing
active fixation electrodes for electrical medical leads, in
particularly helix electrodes intended to be screwed into body
tissue.
BACKGROUND OF THE INVENTION
[0003] Implantable medical electrical stimulation and/or sensing
leads (also called "leads" or "electrode leads") are well known in
the fields of tissue and organ stimulation and monitoring. Such
fields include cardiac pacing. Leads may be attached to an organ by
an active fixation means which is designed to penetrate the surface
of the organ that is to be stimulated or sensed. A common active
fixation means employs a helix which has a sharpened tip and is
mounted at the end of the electrode lead. The fixation helix
typically has an outside helix diameter which is slightly less than
that of the lead body and extends in axial alignment with the lead
body. The sharpened tip of the helix can be screwed into the organ
by being rotated. Typically the helix is electrically connected to
one or more conductors in the electrode lead. These conductors can
be electrically connected to one or more exposed surfaces of the
helix which then can be used as stimulating and/or sensing
electrodes. A fixation helix therefore may contain one or a
plurality of conductors. Typically the outer surface of the helix,
including the exposed surfaces used as electrodes, is partly
covered with a biocompatible coating to minimise interference with
the tissue to which it is to be attached. Typically the
biocompatible coating is electrically conducting and it is arranged
in a predetermined pattern with continuous gaps on the insulating
material around the exposed electrode surfaces in order to prevent
the different electrodes from being in electrical contact with each
other. The sizes of the surface areas of the exposed electrodes are
set at levels which are compatible with the organ they are attached
to. US Patent Application US 2006/0122682 describes an active
fixation helix for an electrical medical leads and methods of
making such active fixation helixes.
SUMMARY OF THE INVENTION
[0004] The present invention relates methods for manufacturing
active helices suitable for use as active fixation electrodes for
electrical medical leads, in particularly helix electrodes intended
to be screwed into body tissue. Such helices are made of thin
electrical conductors, encased in an insulating material--usually
treated to be biocompatible, and twisted into the shape of a helix.
The portions of the conductors are exposed to form electrically
active surfaces which can be used for stimulating or sensing.
[0005] A first embodiment of a method in accordance with the
present invention for making a helix comprises a first step of
producing an elongated helix precursor body comprising one or more
electrical conductors surround by an insulating material. This
helix precursor body is then shaped into a helix, material removed
in predetermined places in order to expose the areas of the
conductors which will be used as electrodes in the final product
and coated with an electrically conducting biocompatible coating
which is subsequently partly removed in continuous loops from
around the electrodes in order to electrically insulate them from
each other and to ensure that the electrically active areas of the
electrodes are of the correct dimensions.
[0006] An alternative embodiment of a method in accordance with the
present invention for making a helix comprises a first step of
producing an elongated helix precursor body comprising one of more
electrical conductors surrounded by an insulating material.
Material is then removed at predetermined places from the helix
precursor body in order to expose the areas of the conductors which
will be used as electrodes in the final product. The body is coated
with an electrically conducting biocompatible coating which is then
removed in continuous loops from around the electrodes in order to
electrically insulate them from each other and to ensure that the
electrically active areas of the electrodes are of the correct
dimensions. The body is then formed in to the shape of a helix.
[0007] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various aspects, all without departing from the spirit and scope of
the present invention. Accordingly, the drawings and detailed
description are to be regarded as illustrative in nature and not
restrictive.
DESCRIPTION OF THE FIGURES
[0008] FIG. 1 shows schematically an example of an electrical
medical lead provided with an active fixation means;
[0009] FIG. 2 shows schematically an embodiment of electrically
active helix having a single conductor;
[0010] FIG. 3 shows schematically an embodiment of a
multi-conductor electrically active helix;
[0011] FIGS. 4a)-4e) show schematically steps in a first method in
accordance with the present invention for making an active fixation
means;
[0012] FIGS. 5a)-5f) show schematically stages in the manufacture
of a multi-conductor helix precursor body;
[0013] FIGS. 6a)-6e) show schematically steps in a second method in
accordance with the present invention for making an active fixation
means; and
[0014] FIGS. 7a)-7c) show schematically cross-sections through
examples of possible helix precursor bodies.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIG. 1 shows schematically an example of an electrical
medical lead 1 provided with an active fixation means 3. The active
fixation means is formed by an electrically active helix 5 having a
proximal end 7 in electrical connection with a conductor (not
shown) inside said electrical medical lead 1 and a sharpened distal
end 9. A plurality of helix revolutions 11 are arranged between
said proximal end 7 and said distal end 9. The helix 5 is attached
to the lead 1 by a sleeve 12 which surrounds the end of the lead
and one or more revolutions 11 of the helix 5.
[0016] FIG. 2 shows schematically an embodiment of electrically
active helix having a single conductor. The helix body 13 surrounds
a longitudinally extending lumen 15 and is comprised of an
electrically conducting core 17 which is at least partially
surrounded by an insulating sheath 21 such that a continuous
portion of the surface 23 said electrically conducting core 17 is
exposed. The exposed surface 23 is coated with an electrically
conducting biocompatible coating 27 and preferably the insulating
sheath is also covered with a biocompatible coating. In order to
electrically insulate the exposed surface 23 of the core 17 from
the rest of the surface of the helix body, a continuous loop of the
surface of the helix surrounding said exposed surface 17 must be
free of electrically conducting material.
[0017] FIG. 3 shows schematically an embodiment of a
multi-conductor electrically active helix. The helix body 33
surrounds a longitudinally extending lumen 35 and is comprised of
electrically conducting cores 37, 39 each of which is at least
partially surrounded by an insulating sheath 41 such that a
continuous portion of the surface 43, respectively 45, of each said
electrically conducting core 37, 39 is exposed. Each exposed
surface 43, 45 of the cores and the insulating sheath 41 is coated
with an electrically conducting biocompatible coating 47 but the
exposed surfaces 43, 45 are electrically insulated from each other
and the sheath 41 by being surrounded by a continuous loop of
insulating material. This is described in more detail below.
[0018] A first embodiment of a method for producing an active
fixation means in the form of a multi-conductor electrically active
helix will now be described in connection with FIGS. 4a)-4e). In a
first step an elongated cylindrical helix body precursor 51 is
formed. This helix body precursor 51 has a proximal end 53 and a
distal end 55 and comprises first and second elongated electrically
conducting cores 37, resp. 39, surrounded by a sheath 41 of
insulating material 42. The cores 37, 39 can be made of any
suitable conducting material, for example a metal such as
platinum.
[0019] An example of such a helix body precursor 51 is shown in
FIG. 4a). In this example the first core 37 is arranged along the
central longitudinal axis of the helix body precursor 51 and the
second core 39 is arranged parallel to the first core 37 and
between the first core 37 and the outer surface 57 of the helix
body precursor. This can be achieved for example by co-extruding
the cores 37, 39 inside an insulating sheath material.
[0020] In the next step of the method a predetermined length of
second core 39 and the insulating material surrounding it are
removed from distal end 55, leaving a shoulder 58 in the helix body
precursor 51, said shoulder extending over a portion of the first
core 37 which is still surrounded by insulating material 42 as
shown in FIG. 4b).
[0021] In a third step, as shown in FIG. 4c) shoulders 59, resp.
61, are formed in the insulating sheath 41 by selectively removing
insulating material from the distal end 55 of the helix body
precursor 51 in order to expose resp. a surface 43 of the first
electrically conducting core 37, and a surface 45 of the second
electrically conducting core 39. In this example shoulder 59 is a
continuation of shoulder 58 in a direction towards the first
electrically conducting core 37 but it is conceivable to place
shoulder 59 further away from the distal end 55 than shoulder 58,
thereby removing or undercutting shoulder 58. In this embodiment of
the present invention part of exposed first core 37 nearest the
distal end 55 of the helix body precursor 51 is levelled so that
the exposed surface 43 is coplanar with the longitudinally
extending surface 62 of shoulder 59. Similarly part of exposed
second core 39 nearest the distal end 55 of the helix body
precursor 51 is removed so that its exposed surface 45 is coplanar
with the longitudinally extending surface 64 of shoulder 61. As
alternatives one or more of the exposed surfaces of the cores can
be left standing proud of the surrounding longitudinally extending
surface e.g. with a convex exposed surface, or, conversely, one or
more exposed cores surfaces can be sunk into the surrounding
longitudinally extending surface, e.g. with a concave exposed
surface. While this step has been described as following the
preceding step it is of course possible to perform these two steps
substantially simultaneously.
[0022] Subsequently, as shown in FIG. 4d) a continuous electrically
conducting biocompatible coating 47 can be applied to the exposed
surface of said helix body precursor so that it covers the
insulating sheath, shoulders 59, 61 and the exposed surfaces 43, 45
of the electrically conducting cores 37, 39.
[0023] Finally, as shown in FIGS. 4e) and 4f) a continuous loop 71,
resp. 73 of said electrically conducting biocompatible coating 47
on the insulating sheath surrounding each of the exposed surfaces
43, 45 of the electrically conducting cores 37, 39 is removed. The
result of this is that each electrically conducting coating on the
exposed surface 43, 45 of each core 37, 39 is not in electrical
contact with the remaining electrically conducting coating 47 on
said insulating sheath. This limits the electrically-effective
surface area of each exposed core surface which will subsequently
be used as sensing or stimulating electrodes. The biocompatible
coating can be removed by, for example, cutting, polishing,
grinding or similar methods. The elongated helix body precursor can
now be formed into a helical shape comprising an internal lumen by
winding around a cylindrical former or by any other known way in
order to form a helix body comprising a plurality of revolutions
separating a distal end and a proximal end. Preferably the forming
of the helical shape is performed so that the exposed surface of
each core is orientated in a predetermined direction, for example
towards the exterior of the helix. As in this embodiment of the
present invention the forming of the helix revolutions takes place
after the electrically conducting biocompatible coating has been
applied to the insulating sheath, it is preferable that the bonding
of the biocompatible coating to the underlying sheath and exposed
surface of the electrically conducting core is sufficiently strong
that the biocompatible coating is not disturbed or moved during
forming of these revolutions. Examples of coatings which exhibit
such strong bonding are titanium oxide, platinum black, and metal
oxides formed from the conducting wire or lead.
[0024] FIGS. 5a)-5f) show stages in the manufacture of a
multi-conductor electrically active helix in which each conductor
has a plurality of active electrode in accordance with the above
first embodiment of a method for producing an active fixation
means. In these figures the reference numerals used in FIGS.
4a)-4f) have been repeated when they correspond to similar
features. As can be seen from FIGS. 5a)-5f) the stages in this
method are substantially the same as those described above except
that in the third step, as shown in FIG. 5c), a plurality of cuts
are made in the insulating sheath and insulating material removed
from between alternating pairs of cuts in order to form slits 42',
42'', 42'', resp. 44', 44'', 44''' which expose a plurality of
longitudinally extending surfaces 43', 43'', 43'' of the first
electrically conducting core 37, resp. a plurality of
longitudinally extending surfaces 45', 45'', 45''' of the second
electrically conducting core 39. In this embodiment of the present
invention exposed portions of first core 37 nearest the distal end
55 of the helix body precursor 51 are not levelled, i.e. the
exposed surfaces 43', 43'', 43''' project above the longitudinally
extending surfaces 62 of the slits 42', 42'', 42''' formed in
shoulder 59. Similarly the exposed portions of second core 39
nearest the distal end 55 of the helix body precursor 51 are not
levelled, i.e. the surfaces of its exposed surfaces 45', 45'',
45''' project above the longitudinally extending surfaces 64 of the
slits 44', 44'', 44''' formed in shoulder 61. As alternatives one
or more of the exposed surfaces 43'-43''', 45'-45''' of the cores
can made level with the surrounding longitudinally extending slit's
surface or, one or more exposed cores surfaces can be sunk into the
surrounding longitudinally extending slit's surface, e.g. with a
concave exposed surface. While this step has been described as
following the preceding step it is of course possible to perform
these two steps substantially simultaneously.
[0025] Subsequently, as shown in FIG. 5d) a continuous electrically
conducting biocompatible coating 47 can be applied to the exposed
surface of said helix body precursor so that it covers the
insulating sheath, shoulders 59, 61 and the exposed surfaces
43'-43''', 45'-45''' of the electrically conducting cores 37,
39.
[0026] Finally, as shown in FIGS. 5e) and 5f) a continuous loop
71'-71''', resp. 73'-73''' of said electrically conducting
biocompatible coating 47 on the insulating sheath surrounding each
of the exposed surfaces 43'-43''', 45'-45''' of the electrically
conducting cores 37, 39 is removed. The result of this is that each
electrically conducting coating on the exposed surfaces of each
core 37, 39 is not in electrical contact with the remaining
electrically conducting coating 47 on said insulating sheath. This
limits the electrically-effective surface area of each exposed core
surface which will subsequently be used as sensing or stimulating
electrodes. The biocompatible coating can be removed by, for
example, cutting, polishing, grinding or similar methods. The
elongated helix body precursor can now be formed into a helical
shape comprising an internal lumen by winding around a cylindrical
former or by any other known way in order to form a helix body
comprising a plurality of revolutions separating a distal end and a
proximal end. Preferably the forming of the helical shape is
performed so that the exposed surface of each core is orientated in
a predetermined direction, for example towards the exterior of the
helix.
[0027] In a second embodiment of a method for producing an active
fixation means in the form of an electrically active helix, the
helix body precursor is formed into a helical shape before the
surfaces of the conducting core or cores are exposed. Thus this
method is similar to the first embodiment of the invention except
that the forming of the helix is performed before the application
of coatings. In more detail an example of a second embodiment of
the present invention comprises the steps of:
[0028] a) forming a helix body having a proximal end and a distal
end connected by a plurality of helical revolutions, said body
comprising at least one electrically conducting core partially
surrounded by an insulating sheath whereby a continuous portion of
the surface of each electrically conducting core extending from
said distal end towards said proximal end and facing in a
predetermined direction is exposed;
[0029] b) applying a continuous electrically conducting,
biocompatible coating to surface of said insulating sheath and each
exposed surface of each electrically conducting core;
[0030] c) removing a portion of said electrically conducting
biocompatible coating on the insulating sheath surrounding each
continuous portion of the surface of each electrically conducting
core such that the electrically conducting coating on the exposed
surface of each electrically conducting core is not in electrical
contact with the remaining electrically conducting coating on said
insulating sheath.
[0031] In the above examples, the exposed surfaces 43-45''' and
45-45''' which are to act as sensing or stimulating electrodes are
quadratic when seen from a view perpendicular to the exposed
surface and extend longitudinally, but it conceivable for them to
made in any shape.
[0032] There are several possible ways of forming an elongated
helix body precursor. For example, as shown in FIGS. 6a) and 6b) a
electrically conducting core 81 and an insulating sheath 83 can be
extruded simultaneously, the insulating sheath 83 being formed with
a longitudinal slit 85 such that a continuous longitudinally
extended portion of the surface 87 of said electrically conducting
core 81 is exposed and not surrounded by said insulating sheath
83.
[0033] Such an elongated helix body precursor can be formed into a
helix 89 as shown in FIG. 6c), for example by winding around a
former. The complete helix 89 can then be coated with a
biocompatible conductive material 91 such as titanium nitride by,
for example, vapour deposition as shown in FIG. 6d). In order to
isolate the exposed surface 87 of the core 81 which is intended to
be electrically active during use from the surface of the
insulating sheath 83 which is intended to be inactive during use,
continuous strips 93 of the biocompatible conductive material 91 on
the insulating sheath 83 can be removed, by polishing, cutting or
other suitable methods, leaving a continuous non-conducting gap 93
between the core 85 and the major part of the visible surface of
the insulating sheath, as can be seen in FIG. 6e).
[0034] FIGS. 7a)-7c) show schematically examples of further
possible helix body precursors in cross-section. FIG. 7a) shows a
cross-section through a co-extruded or co-formed precursor body 101
containing two symmetrically-positioned conducting cores 103, 105
of circular cross-section surrounded by a circular insulating
sheath 107.
[0035] FIG. 7b) shows a cross-section through a co-extruded or
co-formed precursor body 109 containing three conducting cores 111,
113, 115 each of circular cross-section surrounded by a circular
insulating sheath 117. The cores are arranged with the two cores
positioned at 90.degree. either side of a middle core--thereby
leaving a gap of approximately 180.degree. of insulating material
without any cores. Preferably this gap is arranged to be facing
towards the interior of the helix when the precursor is formed into
a helix.
[0036] FIG. 7c) shows a cross-section through a co-extruded or
co-formed precursor body 119 containing an
asymmetrically-positioned core 121 of quadratic cross-section
positioned inside an insulating sheath 125 of C-shaped
cross-section, with a surface 125 of core 121 exposed.
[0037] The above suggested cross-sections are merely examples of
conceivable cross-sections--the skilled person would understand
that in the event that a lead, precursor body or helix has a
plurality of conductors it is always possible to remove selectively
insulating material in predetermined positions so that when in use
in a patient conductors can come into contact with tissue and
thereby be used as a stimulating and/or sensing electrode.
* * * * *