U.S. patent application number 13/262179 was filed with the patent office on 2012-01-26 for implantable mri compatible medical lead with a rotatable control member.
This patent application is currently assigned to ST JUDE MEDICAL AB. Invention is credited to Kenneth Dahlberg, Henrik Djurling, Mikael Forslund, Patrik Forsstrom, Leda Henriquez, Linn Olsen, ke Sivard, Olof Stegfeldt.
Application Number | 20120022356 13/262179 |
Document ID | / |
Family ID | 42097387 |
Filed Date | 2012-01-26 |
United States Patent
Application |
20120022356 |
Kind Code |
A1 |
Olsen; Linn ; et
al. |
January 26, 2012 |
IMPLANTABLE MRI COMPATIBLE MEDICAL LEAD WITH A ROTATABLE CONTROL
MEMBER
Abstract
A medical implantable lead is adapted to be implanted into a
human or animal body for monitoring and/or controlling of an organ
inside the body. The lead has in a distal end, a combined fixation
means and electrode member in form of a helix, which is connected
to a rotatable tubular member being connected to a rotatable member
at a proximal end of the lead, and which is rotatable in relation
to the lead and extendable out from the distal end, by rotation of
the control member and the tubular torque transferring member, to
be able to fixate the distal end of the lead to the organ by being
screwed into the tissue. The helix is electrically connected to a
connector at the proximal end by means of at least one electrically
conducting wire formed as an electrically conducting coil, which is
separate from the tubular torque transferring member and
unrotatable in relation to the lead and that has one or more
individual wires, each including an electrically conducting wire
core and a surrounding electrically insulating layer, wherein the
rotatable control member is rotatable within the connector.
Inventors: |
Olsen; Linn; (Sundbyberg,
SE) ; Forslund; Mikael; (Stockholm, SE) ;
Djurling; Henrik; (Jarfalla, SE) ; Forsstrom;
Patrik; (Jarfalla, SE) ; Henriquez; Leda;
(Jarfalla, SE) ; Dahlberg; Kenneth; (Jarfalla,
SE) ; Stegfeldt; Olof; (Jarfalla, SE) ;
Sivard; ke; (Jarfalla, SE) |
Assignee: |
ST JUDE MEDICAL AB
|
Family ID: |
42097387 |
Appl. No.: |
13/262179 |
Filed: |
October 30, 2009 |
PCT Filed: |
October 30, 2009 |
PCT NO: |
PCT/SE09/00480 |
371 Date: |
September 29, 2011 |
Current U.S.
Class: |
600/373 ;
607/116 |
Current CPC
Class: |
A61N 1/057 20130101;
A61N 1/3752 20130101 |
Class at
Publication: |
600/373 ;
607/116 |
International
Class: |
A61N 1/05 20060101
A61N001/05; A61B 5/04 20060101 A61B005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2009 |
SE |
PCT/SE2009/000169 |
Jul 10, 2009 |
SE |
PCT/SE2009/000364 |
Claims
1.-10. (canceled)
11. An MRI-compatible medical implantable lead comprising: a lead
body adapted to be implanted into a human or animal body for
monitoring and/or controlling an organ inside the body; a
connecting structure comprising a connector pin at a proximal end
of the lead body, said connector pin comprising a rotatable control
member; a rotatable tubular torque transferring member connected to
the rotatable control member; a combined fixation means and
electrode member in form of a helix at a distal end of the lead,
said helix being connected to said rotatable tubular torque
transferring member and being rotatable in relation to the lead
body and extendable out from said distal end, by rotation of the
control member and the tubular torque transferring member, for
fixation of the lead to the organ; a connector at said proximal end
of the lead body electrically connected to the helix by at least
one electrically conducting wire formed as an electrically
conducting coil, said coil being separate from the tubular torque
transferring member and rotatably fixed in relation to the lead,
whereby the tubular torque transferring member is rotatably
arranged within the electrically conducting coil and having no
electrically conducting function to or from the helix; said
electrically conducting coil comprising one or more individual
wires, each comprising an electrically conducting wire core and a
surrounding electrically insulating layer; and said connector pin
comprising said control member and said connector, said control
member being rotatably arranged within said connector.
12. A medical implantable lead according to claim 11, wherein the
control member is electrically insulated from the connector.
13. A medical implantable lead according to claim 11, wherein the
control member and the connector are electrically insulated from
each other by an electrically insulating member.
14. A medical implantable lead according to claim 13, wherein the
electrically insulating member is an electrically insulating sleeve
and the connector is arranged at the outer circumference of the
insulating sleeve.
15. A medical implantable lead according to claim 13, wherein the
electrically insulating member is in one unitary piece.
16. A medical implantable lead according to claim 13, wherein the
electrically insulating member is non-rotatably mounted to said
connector, and said control member is rotatable inside said
insulating member.
17. A medical implantable lead according to claim 13, wherein the
electrically insulating member is non-rotatably mounted to said
control member, and said control member and said electrically
insulating member are jointly rotatable within said connector.
18. A medical implantable lead according to claim 11, wherein that
the connector is a metallic sleeve completely surrounding the
control member.
19. A medical implantable lead according to claim 18, wherein the
control member has a rotary engagement portion configured to engage
a rotary tool.
20. A medical implantable lead according to claim 19, wherein the
rotary engagement portion is a recess having engagement formations
at the proximal end of the control member.
21. A medical implantable lead according to claim 11, wherein the
control member projects with a proximal portion beyond the
connector at the proximal end of the lead body.
22. A medical implantable lead according to claim 21, wherein the
proximal portion of the control member is adapted to be gripped by
a gripping tool for rotation of the control member.
23. A medical implantable lead according to claim 11, wherein said
connecting structure comprises a thickened portion and said
connector is non-rotatably mounted to said thickened portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a medical implantable lead of the
kind being adapted to be implanted into a human or animal body for
monitoring and/or controlling of an organ inside the body,
comprising at a distal end a combined fixation means and electrode
member in form of a helix, which is connected to a rotatable
tubular torque transferring member being in its turn connected to a
rotatable control member at a proximal end of the lead, and which
is rotatable in relation to the lead and extendable out from the
distal end, by rotation of the control member and the tubular
torque transferring member, to be able to fixate the distal end of
the lead to the organ by being screwed into the tissue, wherein the
helix is electrically connected to a connector at the proximal end
by means of at least one electrically conducting wire.
[0003] 2. Description of the Prior Art
[0004] It is well known in the art to use a medical implantable
lead of the above kind to monitor and/or control the function of an
organ inside a human or animal body, for example to monitor and/or
control a heart by means of a monitoring and/or controlling device
in form of a pacemaker or cardiac defibrillator connected to the
proximal end of the lead. The medical implantable lead is provided
with at least one electrical conductor, in form of a coil having
one or more helically formed electrically conducting wires,
sometimes also referred to as filars, which connects one or more
connectors arranged at the proximal end of the lead with one or
more electrodes in its distal end. At least one of the electrodes
is formed as a helix, which is adapted to be screwed into the
tissue of the organ for receiving and/or transmitting electrical
signals from and/or to the organ and transmit them, through the
electrically conducting coil, to the monitoring and/or controlling
device connected to the proximal end of the lead. The helix also
functions as an attachment means for attaching the distal end of
the lead to the organ by being rotatably extended out from the
distal end of the lead and accordingly screwed into the tissue of
the organ. To accomplish the rotation of the helix, it is
mechanically connected to the innermost one of the electrically
conducting coils, which accordingly has to be rotatable in relation
to the lead as well as be sufficiently rigid to be able to transmit
the required torque from the proximal to the distal end. The lead
may also be provided with one or more additional electrodes
separate from the helix and e.g. be formed as a contact electrode,
abutting against a surface of the organ, or be formed as a so
called indifferent electrode which is surrounded by body fluids
such as blood.
[0005] Normally, such medical implantable leads are not considered
to be compatible with Magnetic Resonance Imaging (MRI), i.e.
persons or animals having such a lead implanted into the body, are
excluded from being examined by MRI-scanning. This is due to the
fact that the electromagnetic field, that is generated during the
MRI-scanning, will induce a current in the conductor, which
connects the one or more electrodes at the distal end of the
medical implantable lead with the monitoring and/or controlling
device at the proximal end of the lead. This induced current may
cause heating at an electrode being in contact with the tissue of
the organ, especially if the electrode is in form of a helix which
is penetrated into and embedded within the tissue. If the heating
is too high, there is a risk that this will cause damages to the
tissue. However, the use of MRI-scanning for diagnostics is growing
extensively and an increasing number of the population having a
lead implanted would benefit from MRI-scans. It is thus desirable
to reduce any heating at or close to the lead tip to acceptable and
safe levels to allow MRI-scanning also of persons or animals having
such a lead implanted.
[0006] It is known in the art to provide such medical implantable
leads with an electrical shielding, in form of a tube of braided
wires, which surrounds the coil and which in its proximal end
normally is connected to the casing of the monitoring and/or
controlling device. However, such shielded medical implantable
leads are associated with several disadvantages. On the one hand,
the braided shielding will give the medical implantable lead an
increased thickness as well as increased rigidity, which normally
is not desirable. On the other hand, it has appeared that such a
braided shielding cannot prevent the induction of electrical
current to the coiled conductor in a degree that is sufficient to,
without risk, expose an individual, having an implanted lead, to a
MRI-scanning.
[0007] U.S. Pat. No. 7,363,090 discloses a way to reduce heating
caused by induced current from MRI-scanning by connecting a contact
electrode and an indifferent ring electrode in series with a band
stop filter, which are tuned to certain frequencies utilized during
MRI-scanning. Such a prior art medical implantable lead comprises
passive electronic components, which contribute to making the lead
more complex and thus more costly to manufacture.
SUMMARY OF THE INVENTION
[0008] It is an object of the invention to provide a medical
implantable lead, which in a simple and cost-effective way reduces
the induction of current from an electromagnetic field into the
electrically conducting coil.
[0009] The basis of the invention is the insight that the above
object may be achieved by separating the function of effecting
rotation and extending the helix out from the distal end of the
lead, from the function of transmitting the electrical signals
between the helix and, where appropriate, the one or more further
electrodes at the distal end and the one or more connectors at the
proximal end, i.e. to split these functions on separate members
within the lead. More precisely, the function of transmitting a
torque from the proximal end to the distal end for effecting
rotation of and extending the helix out from the distal end, is
effected by an inner tubular torque transferring member, which has
no electrically conducting function to or from the electrode,
whereas the electrically conducting function to and from the
electrode is effected by a separate electrically conducting coil
formed of one or more helical wires. Each wire is moreover coated
with an electrically insulating layer, such that the coil will form
an inductor, which will allow the low frequency signals between the
electrode and the monitoring and/or controlling device to pass
through without being exposed to high impedance. On the other hand,
for induced current from high frequency electromagnetic fields,
such as fields from MRI-scanning typically operating at 64 or 128
MHz, the impedance in the electrically conducting coil will be very
high which to a large extent will restrain induced high frequency
currents.
[0010] According to the invention, also at the proximal end of the
lead, the function of performing rotation of the torque
transferring member, and consequently the helix, is separated from
the function of conducting an electrical current between a
connector at the proximal end via the electrically conducting coil
and the helix. More precisely, the rotation of the torque
transferring member is effected by rotation of a control member at
the proximal end, which control member is connected to the torque
transferring member and rotatably arranged coaxially within a
connector. The connector is in turn electrically connected to the
electrically conducting coil, which is rotatably fixed in relation
to the lead. In case the torque transferring member and/or the
control member is electrically conductive, the connector and the
control member are electrically insulated from each other to
prevent induced current from a magnetic field into the torque
transferring member and/or the control member to be transmitted to
the connector and the electrically conducting coil, as well as the
helix. In other words, the lead is arranged such that the
electrical connection between the helix and the conducting wire is
maintained regardless of the rotational position of the helix,
while no electrical connection is present between the helix and the
tubular torque transferring member even though the helix is
rotatable by means of the tubular torque transferring member, and
the rotatable control member is rotatable within the connector.
[0011] By forming the medical implantable lead in this way, it is
possible to form the tubular torque transferring member with a
sufficient mechanical strength and stiffness to be able to transfer
the torque required, from the proximal end to the distal end, to
rotate the helix for extending it out from the distal end of the
lead and screw it into the tissue. The electrically conducting
coil, on the other hand, can be optimized to present an as high
inductance as possible. For example, since the electrically
conducting coil does not have to transfer any torque to the helix,
it can be formed of one or only a few wires, which each can be made
very thin. In this way, the pitch of the individual wires of the
coil will be very low, which will increase the inductance of the
coil. Also, since the electrically conducting coil will be
positioned around the torque transferring member, the diameter of
the coil can be made larger than what is possible with the prior
art combined electrically conducting and torque transferring coils.
This will also increase the inductance.
[0012] Within this overall idea, the invention may be modified in
many different ways. As stated, the torque transferring member is
tubular having an inner bore. This is done for the purpose of
allowing insertion of a guide wire into the inner bore to enable
guiding of the distal end of the lead to a desired location inside
a body. Hence, the diameter of the inner bore is large enough for
the guide wire to be inserted into the bore. Besides this
requirement, the torque transferring member can be formed in many
different ways. In the prior art, the torque transferring member is
normally formed of three to five comparatively thick, metallic
wires in order to function both as an electrical conductor as well
as a torque transferring member. The several rather thick wires
will give the coil a sufficient mechanical strength to transfer the
required torque, but will also give the coil a rather large pitch,
which will reduce the inductance. Also, the torque transferring
member according to the invention may be formed in a similar way,
with the exception that the wires are not electrically conducting
between an electrode at the distal end and a connector at the
proximal end. However, the torque transferring member could also be
formed of an electrically non-conducting material, such as e.g. a
polymeric material, which can be formed as a coil of one or more
helical threads or as a flexible tubing.
[0013] The medical implantable lead can be provided with more than
one electrode, e.g. two electrodes for a bipolar lead, three
electrodes for a tripolar lead, etc. The electrically conducting
wires for each electrode can optionally be provided in separate
coils, which are co-axially arranged in relation to each other, or
two or more separate electrically conducting wires, dedicated for
different electrodes, can be provided side by side in one and the
same coil. One advantage with an embodiment according to the latter
case is that the overall diameter of the lead can be made smaller
than in the former case. However, the inductance will be somewhat
lower in the latter case in relation to the former, since the pitch
of each individual wire will be somewhat larger. This can be
alleviated by forming the coil from wires having a sufficient thin
cross section.
[0014] Since the helix functions as an electrode, and is rotatable
in relation to the lead, together with the torque transmitting
member, arrangements should be made in respect of the electrical
connection of the helix to the electrically conducting coil. This
is due to the fact that the electrically conducting coil dedicated
for the helix is non-rotating while the torque transferring member
is rotatable in relation to the electrically conducting coil. The
electrical connection between the helix and the coil can be ensured
by e.g. arranging a sliding electrical contact between the helix
and the specific wire. However, the electrical connection between
the electrically conducting coil and the helix may be maintained
also in many other ways, as realized by the skilled person.
[0015] In a medical implantable lead according to the invention,
the mechanical transfer of torque from the proximal to the distal
end, for rotating and extending the helix for screwing it into the
tissue, is separated from the electrical conducting between the
monitoring and/or controlling device and an electrode member in
form of a helix at the distal end. More precisely, the torque is
transferred by means of a tubular torque transferring member, which
does not transfer any electrical current between the monitoring
and/or controlling device and the helix. On the other hand, the
electrical signals are conducted by a coil arranged on the outside
of the torque transferring member and formed by helically wound
wires having an outer non-conducting layer, such that adjacent
loops of the coil will be electrically insulated from each other
and the coil will function as an inductor. By a medical implantable
lead formed in this way, it is possible to achieve a sufficient
inductance in the conducting coil to prevent or at least reduce the
strength of induced high frequency current from an electromagnetic
field, into the electrically conducting coil to a sufficient degree
that is harmless for the tissue. At the same time, the torque
transferring member can be made with a sufficient strength and
rigidity to allow transferring of the torque required. In
embodiments of the invention, the electrically conducting coil may
e.g. be formed of a wire comprising a silver core, which presents
an advantageous low resistance to the signals and therefore can be
given a small cross sectional dimension, such that the coil can be
formed with a small pitch which will increase the inductance. The
non-conducting layer around the wire core may be formed of a
mineral or a polymer, such as e.g. ETFE (Ethylene Tetra Fluor
Ethylene).
[0016] Since the inner tubular torque transferring member is
mechanically connected to the helix but has no electrically
conducting function to and from the helix, whereas the electrically
conducting coil arranged outside of the tubular torque transferring
member is not adapted to mechanically transfer any torque to the
helix, the one or more conducting wires in the electrically
conducting coil are arranged to always maintain the electrical
connection between a connector at the proximal end and the helix at
the distal end irrespective of the rotated position of the tubular
torque transferring member and the helix.
[0017] Within the overall idea, the invention may be altered and
modified in many different ways. For example, the tubular torque
transferring member may optionally be formed as a flexible tube or
as a helical coil of one or more threads or wires. It may also
optionally be formed of an electrically insulating or a conducting
material. In the former case no special measures has to be taken
for insulating the tubular torque transferring member electrically
from the helix or from the connector at the proximal end, such as
may have to be done in case the tubular torque transmitting member
is formed of an electrically conducting material. The connecting
structure at the proximal end of the lead, which is adapted to be
connected to a monitoring and/or controlling device, is formed with
a connector pin which comprises an inner control member and a
connector arranged co-axially outside of the control member.
Accordingly, at least a part of the outer surface of the connector
pin will be formed by the connector, which is electrically
connected to an electrically conducting coil and the helix and
which is adapted to be electrically connected to the monitoring
and/or controlling device. The control member is rotatably arranged
within the connector and mechanically connected to the torque
transferring member and the helix. The control member can
optionally be entirely surrounded by the connector such that only a
proximal end of the control member is visible and accessible, in
which case some form of engagement means has to be formed at the
end surface for engagement with a suitable rotary tool for
performing rotation of the torque transferring member and the
helix, or project a distance out from the proximal end of the
connector such that it forms a part of the surface of the connector
pin. In the latter case rotation may be performed by gripping the
control member by means of a gripping tool around the outer
surface. Preferably, the projecting part of the control member is
formed with an enlarged cross section such that it will have the
same diameter as the connector. Moreover, the control member is
preferably electrically insulated from the connector in case the
torque transferring member and/or the control member is
electrically conductive, e.g. metallic. The electrical insulation
can preferably be formed as a sleeve surrounding the control
member, but could also be formed as e.g. two ring members at a
distance from each other. The control member may either be
rotatable within the electrical insulation, or the electrical
insulation may be rotatable within the connector.
[0018] The embodiments described and illustrated hereinafter are
given solely for exemplifying reasons and are not intended to be
comprehensive. Accordingly, many other embodiments could be
conceivable within the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view of a medical implantable
lead.
[0020] FIG. 2 is a view in an enlarged scale of the lead in FIG. 1
in a shortened state showing only the proximal and the distal ends
of the lead.
[0021] FIG. 3 is a longitudinal section along the line A-A in FIG.
2 of a portion of a medical implantable lead according to a first
embodiment.
[0022] FIG. 4 is a cross section along the line B-B in FIG. 2 of
the lead according to FIG. 3.
[0023] FIG. 5 is a longitudinal section along the line A-A in FIG.
2 of a portion of a medical implantable lead according to a second
embodiment.
[0024] FIG. 6 is a cross section along the line B-B in FIG. 2 of
the lead according to FIG. 5.
[0025] FIG. 7 is a longitudinal section through a distal portion of
the medical implantable lead, illustrating an embodiment of the
electrically connection to the electrodes as well as the
mechanically connection to the helix, which is in a retracted
state.
[0026] FIG. 8 is a longitudinal section according to FIG. 7 with
the helix in an extended state.
[0027] FIG. 9 is a longitudinal section through the proximal end of
a lead according to a first embodiment of the invention.
[0028] FIG. 10 is a combined longitudinal section and perspective
view of the lead according to FIG. 9 together with a perspective
view of a rotary tool.
[0029] FIG. 11 is a perspective view of the proximal end of the
lead according to FIGS. 9 and 10.
[0030] FIG. 12 is a perspective view of a rotary tool for
interaction with a medical implantable lead according to FIGS.
9-11.
[0031] FIG. 13 is a longitudinal section through the proximal end
of a lead according to a second embodiment of the invention.
[0032] FIG. 14 is a combined longitudinal section and perspective
view of the lead according to FIG. 13.
[0033] FIG. 15 is a perspective view of the proximal end of the
lead according to FIGS. 13 and 14.
[0034] FIG. 16 is a perspective view of the proximal end of the
lead and a clamp gripping around the control member.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Reference is first made to FIG. 1, in which is illustrated a
medical implantable lead according to the invention in a
perspective view. The lead has a connecting structure 1 at a
proximal end for connection to a not shown monitoring and/or
controlling device such as a pacemaker or the like, an intermediate
flexible lead part 2, and a so called header 3 at a distal end. The
header is provided with a helix 4, which can be screwed out in the
axial direction of the lead from a cavity at the distal end of the
header. The helix has the function of attaching the distal end of
the lead to the heart, by being screwed into the tissue, and also
functions as an electrode for receiving and/or transmitting
electrical signals from and to the tissue, respectively. The header
is also provided with a second electrode, a so called indifferent
electrode 5, which is formed as a ring and positioned a small
distance from the distal end and has the purpose of forming a
complete current path together with the helix.
[0036] The proximal and the distal ends of the lead according to
FIG. 1, are illustrated in an enlarged scale in the shortened
representation of the lead in FIG. 2. The helix 4 for fixation of
the distal end of the lead to tissue as well as for function as an
electrode is shown in an extended state. However, during insertion
of the lead into a body, the helix is retracted into the bore of
the header 3 having a tubular shape at the distal end. In addition
to a tip electrode in form of the helix, which is adapted to be
screwed into the tissue, the lead has, as is mentioned above, a
second electrode in form of the ring electrode 5 on a short
distance from the distal end.
[0037] At the proximal end, the connecting structure 1 for
connection to a not shown monitoring and/or controlling device
comprises a first fluid tight sealing member 6 and a second fluid
tight sealing member 6'. The sealing members are formed of an
elastic material, in order to achieve a fluid tight connection to a
socket recess of the monitoring and/or controlling device. In the
area being positioned proximal in relation to the first sealing
member 6, the lead is provided with a first electrically conducting
connector 7 and in the area between the first and second sealing
members the lead is provided with a second electrically conducting
connector 7', as is described more in detail below, which are
adapted to be electrically coupled to mating connectors inside the
monitoring and/or controlling device. The first connector 7 is in
electrical contact with the helix 4, whereas the second connector
7' is in electrical contact with the ring electrode 5 by means of
one or more electrical conducting coils inside the lead, as is to
be explained more in detail below. In the most proximal end, the
lead is provided with a rotatable control member 8, which in the
embodiment of FIG. 2 is surrounded by the first connector 7 and
accordingly not visible therein. The control member 8 is, according
to the invention, separated from the connectors 7, 7' and by means
of the control member the helix 4 can be rotated and screwed out
from the bore inside the header 3 and into the tissue.
[0038] Now reference is made to FIGS. 3 and 4, in which are
illustrated a first embodiment of the flexible lead part 2 in a
longitudinal section as well as a cross section through the lead,
respectively. The lead comprises an inner tubular torque
transferring member 9, an inner fluid tight tubing 10, an
electrically conducting coil 11 and an outer fluid tight tubing 12.
The inner tubular torque transferring member is rotatable arranged
inside the inner tubing and is formed as a coil of five
comparatively thick and rigid helical wires of e.g. metal or
polymer, such that it is well suited for transferring of a torque
from the proximal to the distal end of the lead. Moreover, the
torque transferring member 9 defines an inner bore 13 for the
purpose of allowing insertion of a guide wire or the like for
guiding the tip of the lead to a desired position inside a body.
The electrically conducting coil 11 is composed of two separate,
co-radially wound wires 14, 14', each having an electrically
conducting core 15 and a surrounding electrically insulating layer
16, such that they form two electrically separated inductance
coils.
[0039] With reference also to FIG. 2, it is to be understood that
the structure of the flexible lead part 2 as illustrated in FIGS. 3
and 4, extends from the connecting structure 1 at the proximal end
to the header 3 at the distal end. Moreover, the tubular torque
transferring member 9 is in its proximal end mechanically connected
to the rotatable control member 8 and in its distal end
mechanically connected to the helix 4, such that by rotating the
rotatable control member it is possible to rotate the helix and
extend it out from the inner bore of the header and screw it into
the tissue. One of the wires in the electrically conducting coil 11
is in its proximal end electrically connected to the first
connector 7 and in its distal end electrically connected to the
helix 4, whereas the other wire in the electrically conducting coil
is in its proximal end electrically connected to the second
connector 7' and in its distal end electrically connected to the
ring electrode 5.
[0040] Reference is then made to FIGS. 5 and 6, in which are
illustrated a second embodiment of the flexible lead part 2 in a
longitudinal section as well as a cross section through the lead,
respectively. As in the first embodiment according to FIGS. 3 and
4, this embodiment has an inner tubular torque transferring member
9, formed in a similar way as in the first embodiment of five
helical wires, and an inner fluid tight tubing 10. However, this
embodiment has two separate electrically conducting coils, one
inner coil 17 and one outer coil 17', separated by an intermediate
fluid tight tubing 18. Each of the electrically conducting coils is
formed of one single wire 14 and 14', respectively, having an
electrically conducting core 15 and a surrounding electrically
insulating layer 16, such that they form two coaxially arranged
inductance coils. Also this embodiment has an outer fluid tight
tubing 12.
[0041] As in the first embodiment, the tubular torque transferring
member 9 is in its proximal end mechanically connected to the
rotatable control member 8 and in its distal end mechanically
connected to the helix 4, such that by rotating the control member
it is possible to rotate the helix and extend it out from the inner
bore of the header and screw it into the tissue. The inner
electrically conducting coil 17 is in its proximal end electrically
connected to the first connector 7 and in its distal end
electrically connected to the helix 4, whereas the outer
electrically conducting coil 17' is in its proximal end
electrically connected to the second connector 7' and in its distal
end electrically connected to the ring electrode 5.
[0042] Reference is then made to FIGS. 7 and 8 of the drawings, in
which is illustrated an embodiment of a connection of the
electrically conducting wires 14, 14' to the electrodes as well as
the tubular torque transferring member 9 to the helix 4. FIGS. 7
and 8 are longitudinal sections through the distal portion of a
medical implantable lead, according to the embodiment as
illustrated and described in relation to FIGS. 3 and 4, with the
helix being retracted and extended, respectively.
[0043] The longitudinal sections of FIGS. 7 and 8 are taken at the
joint between the header 3, as seen to the right, and the distal
end portion of the flexible lead part 2 as illustrated in FIGS. 3
and 4. The header is made of a rigid material such as metal or a
polymer and is formed with an inner bore 19, in which the helix 4
is rotatably and displaceably accommodated. In the joint region
between the header and the flexible lead part, the electrically
conducting ring electrode 5 is provided, which also functions as a
joint connector in that it comprises a distal shoulder surface, in
which the proximal end of the header 3 is located and attached, and
a proximal shoulder surface in which the distal end of the flexible
lead part 2 is located and attached. A short distance towards the
distal end from the ring electrode 5, the lead is provided with a
fixed support member 20. Both the ring electrode 5 and the support
member 20 are formed with a through bore, through which a shaft 21
is rotatably and displaceably inserted, at the distal end of which
the helix 4 is mounted. The shaft 21 is of an electrically
conducting material and to prevent electrical connection between
the shaft 21 and the ring electrode 5 as well as the support member
20, in case it is manufactured of an electrically conducting
material, electrically insulating shaft bushings 22 are arranged in
each of the through bores. To allow rotation and displacing of the
helix 4 out from and into the inner bore 19 of the header, the
tubular torque transmitting member is mechanically connected to the
proximal end of the shaft. In case the tubular torque transferring
member 9 is of an electrically conducting material, the connection
is arranged in an electrically non-conducting fashion, such as via
an electrically insulating sleeve 23 or the like. The electrically
conducting coil of the lead comprises two electrically conducting
wires 14, 14', which are electrically insulated from each other. To
accomplish electrical connection to each of the ring electrode 5
and the helix 4, one of the electrical conducting wires 14' is
electrically connected to the ring electrode 5, whereas the other
electrically conducting wire 14 is electrically connected to a
sliding contact 24 arranged on the support member 20, the sliding
contact being in permanent electrically contact with the shaft 21,
which is in electrically contact with the helix 4. In this way an
electrically connection is ensured with the helix in spite of the
fact that the tubular torque transferring member 9 is not
electrically conducting and irrespective of the position of the
helix.
[0044] The embodiment of FIGS. 7 and 8 are only an exemplifying
embodiment of how the mechanical and electrical connections between
the helix 4 and the tubular torque transferring member 9 and the
electrically conducting coils 14, 14', respectively, can be
maintained as well as separated. It is to be understood, however,
that this embodiment is only exemplary and that these functions can
be realized also in many other different ways.
[0045] Now reference is made to FIGS. 9 to 11 for a detailed
description of a first embodiment of the arrangement of the
connecting structure at the proximal end of the medical implantable
lead according to the invention. As can be seen, the connecting
structure is comprised of a thickened portion 25 and a connector
pin 26 protruding from the proximal end of the thickened portion. A
first fluid tight sealing member 6 is arranged around the connector
pin adjacent the proximal end of the thickened portion. A second
fluid tight sealing member 6' is arranged around the thickened
portion in an intermediate position of the same.
[0046] In prior art, normally the entire connector pin 26 is
metallic and functions both as an electrical connector, which is in
electrical connection with an inner electrically conducting coil
connected to the helix at the distal end, as well as a rotatable
control member for performing rotation of the helix by being
rotatably mounted in the thickened portion. However, according to
the invention, the connector pin is composed of an inner rotatable
control member 8, which is connected to the inner torque
transferring member 9 and is rotatably arranged within an outer,
tubular electrically conducting connector 7, which in its turn is
unrotatably mounted to the thickened portion and electrically
connected to the helix 4 at the distal end via an electrically
conducting coil 11, which is separated from the torque transferring
member 9.
[0047] In this embodiment, the torque transferring member 9 and the
control member 8 are metallic and accordingly electrically
conductive. To prevent transfer of any electrical current, which
may be induced into the torque transferring member by a surrounding
electromagnetic field, from the torque transferring member to the
electrically conducting coil 11 and hence to the helix 4, there is
arranged an electrically insulating layer in form of an insulating
tube 27 between the control member 8 and the connector 7. The
insulating tube may optionally be unrotatably mounted to the
connector 7, in which case the control member 8 is rotatable inside
the insulating tube, or be unrotatably mounted to the control
member, in which case the control member and the insulating tube
are jointly rotatable within the connector. In case the control
member and/or the torque transferring member would be of an
electrically non-conductive material, the insulating tube could be
dispensed with, since in that case no current can be induced into
the torque transferring member from an electromagnetic field.
[0048] The control member 8 is tubular with a through bore 28 to
allow insertion of a not shown guide wire through the control
member and the tubular torque transferring member to the distal end
of the lead. This is done for the purpose of performing guiding of
the distal end of the lead, by means of the guide wire, to a
desired position within a body, e.g. within a heart. As is evident
from the drawings, in this embodiment the control member 8 is
located entirely within the connector 7. To allow rotation of the
control member, and hence also the torque transferring member and
the helix, the proximal end of the through bore 28 in the control
member is hexagonally formed to provide an engagement means 29 for
a complementary formed rotary tool 30, as is illustrated in FIGS.
10 and 12. The rotary tool is formed with a body 31 and a
protruding shaft 32 having a hexagonal cross section to be inserted
into the hexagonally formed engagement means 29 in the control
member 8. Also the rotary tool 30 is provided with a through bore
33 through the body and the shaft to allow insertion of the guide
wire while the rotary tool is connected to the lead.
[0049] The thickened portion of the connecting structure comprises
a proximal electrically insulating portion 34, an intermediary
electrically conducting second connector 7' and a distal
electrically insulating sleeve 35. The lead according to this
embodiment is provided with only one electrically conducting coil
11. However, the electrically conducting coil comprises two
separate electrically conducting wires 14, 14', each surrounded by
an electrically insulating layer 16, as is illustrated in FIGS. 3
and 4. One of the wires 14 is electrically connected to the helix 4
at the distal end and to the distal end of the first connector 7
within the proximal electrically insulated portion 34 of the
thickened portion of the connecting structure at the proximal end
of the lead. The other electrically conducting wire 14' of the
electrically conducting coil 11 is connected to the indifferent
electrode 5 at the distal end and to a distal end of the second
connector 7' which is formed as a protruding flange having a
smaller cross sectional dimension than the rest of the connector.
The connections between the first and second electrically
conducting wires of the electrically conducting coil and the first
and second connector, respectively, appears from FIGS. 9 and
10.
[0050] As is also seen from FIGS. 9 and 10, the outer fluid tight
tubing 12 of the electrically conducting coil 11 is thread over the
flange portion of the second connector 7' and the outer flexible
sleeve 35 is thread onto the flange portion over the fluid tight
tubing for protecting the transition section between the connecting
structure and the flexible lead part.
[0051] Reference is then made to FIGS. 13-15 in which is
illustrated a second embodiment of the arrangement of the
connecting structure at the proximal end of the medical implantable
lead according to the invention.
[0052] As in the embodiment according to FIGS. 9-11, the connecting
structure according to this embodiment comprises a thickened
portion 25 and a connector pin 26 protruding from the proximal end
of the thickened portion. A first fluid tight sealing member 6 is
arranged around the connector pin adjacent the proximal end of the
thickened portion. A second fluid tight sealing member 6' is
arranged around the thickened portion in an intermediate position
of the same.
[0053] Moreover, the connector pin 26 is composed of an inner
rotatable control member 8, which is connected to the inner torque
transferring member 9 and is rotatably arranged within an outer,
tubular electrically conducting connector 7, which in its turn is
unrotatably mounted to the thickened portion and electrically
connected to the helix 4 at the distal end via an electrically
conducting coil 11, which is separated from the torque transferring
member 9.
[0054] The torque transferring member 9 and the control member 8
are metallic and accordingly electrically conductive. To prevent
transfer of any electrical current from the torque transferring
member to the electrically conducting coil 11 and hence to the
helix 4, there is arranged an electrically insulating layer in form
of an insulating tube 27 between the control member 8 and the
connector 7. The insulating tube may optionally be unrotatably
mounted to the connector 7, in which case the control member 8 is
rotatable inside the insulating tube, or be unrotatably mounted to
the control member, in which case the control member and the
insulating tube are jointly rotatable within the connector.
[0055] The control member 8 is tubular with a through bore 28 to
allow insertion of a not shown guide wire through the control
member and the tubular torque transferring member to the distal end
of the lead. This is done for the purpose of performing guiding of
the distal end of the lead, by means of the guide wire, to a
desired position within a body, e.g. within a heart.
[0056] The thickened portion of the connecting structure comprises
a proximal electrically insulating portion 34, an intermediary
electrically conducting second connector 7' and a distal
electrically insulating sleeve 35. The lead also according to this
embodiment is provided with only one electrically conducting coil
11, comprising two separate electrically conducting wires 14, 14',
each surrounded by an electrically insulating layer 16, as is
illustrated in FIGS. 3 and 4. One of the wires 14 is electrically
connected to the helix 4 at the distal end and to the distal end of
the first connector 7 within the proximal electrically insulated
portion 34 of the thickened portion of the connecting structure at
the proximal end of the lead. The other electrically conducting
wire 14' of the electrically conducting coil 11 is connected to the
indifferent electrode 5 at the distal end and to a distal end of
the second connector 7' which is formed as a protruding flange
having a smaller cross sectional dimension than the rest of the
connector. The connections between the first and second
electrically conducting wires of the electrically conducting coil
and the first and second connector, respectively, appears from
FIGS. 9 and 10.
[0057] As is also seen from FIGS. 9 and 10, the outer fluid tight
tubing 12 of the electrically conducting coil 11 is thread over the
flange portion of the second connector 7' and the outer flexible
sleeve 35 is thread onto the flange portion over the fluid tight
tubing for protecting the transition section between the connecting
structure and the flexible lead part.
[0058] As described so far, this embodiment is identical with the
first embodiment. However, in this embodiment the connector pin 26
has a somewhat different structure. More precisely, the control
member 8 is not entirely surrounded by the connector 7. Instead the
control member projects from the proximal end of the connector
where it is formed with an increased proximal portion 36 having a
cross sectional dimension that is equal to the cross sectional
dimension of the rest of the connector pin and consequently the
control member constitutes the outer surface of the proximal end of
the connector pin. To insulate the control member 8 electrically
from the first connector 7, also the insulating tube 27 between the
control member and the connector is formed with an increased
proximal portion 37 having a cross sectional dimension that is
equal to the cross sectional dimension of the rest of the connector
pin, such that the connector pin is provided with an insulating
surface between the control member and the first connector.
[0059] Moreover, the control member is not formed with any specific
engagement means for engagement with a rotary tool, as in the
embodiment according to FIGS. 9-11. To rotate the torque
transferring member and the helix during implanting of the lead
inside a body, the proximal portion 36 may instead be gripped by
means of an arbitrary gripping tool such as a clamp 38, as is
illustrated in FIG. 16. The clamp 38 is made of an elastic
material, such as a plastic, and comprises two shanks 39, 39' which
are formed as one unitary piece and being connected in a connecting
portion 40 adjacent a lower end, wherein the clamp forms a gripping
portion 41 in form of a recess below the connecting portion.
Accordingly, by gripping upper ends of the shanks 39, 39' by hand,
a physician can displace them towards each other, in which case the
gripping portion 41 in the lower end will open up due to elastic
deformation in the connecting portion 40 such that the gripping
portion may be positioned over the proximal portion 36 of the
control member 8. Due to the elastic characteristics in the
material, the gripping portion will clamp around the control member
such that the physician may rotate the control member, and hence
also the helix 4 at the distal end, by rotating the clamp 38.
[0060] Although modifications and changes may be suggested by those
skilled in the art, it is the intention of the inventors to embody
within the patent warranted heron all changes and modifications as
reasonably and properly come within the scope of their contribution
to the art.
* * * * *