U.S. patent application number 14/877728 was filed with the patent office on 2017-04-13 for left ventricular lead with active fixation.
The applicant listed for this patent is PACESETTER, INC.. Invention is credited to Gene A. Bornzin, Zoltan Somogyi, Didier Theret.
Application Number | 20170100581 14/877728 |
Document ID | / |
Family ID | 58499228 |
Filed Date | 2017-04-13 |
United States Patent
Application |
20170100581 |
Kind Code |
A1 |
Bornzin; Gene A. ; et
al. |
April 13, 2017 |
LEFT VENTRICULAR LEAD WITH ACTIVE FIXATION
Abstract
Disclosed herein is a left ventricular lead for tracking over a
guide wire into a coronary sinus and providing active fixation in,
or adjacent to, the coronary sinus. The guide wire is configured
for coronary sinus lead implantation and has an outer diameter. In
one embodiment, the lead includes a tubular body including a
proximal end, a distal end and a central lumen through which the
guide wire is extendable. The lead also includes a lead connector
end proximally projecting from the proximal end and comprising at
least one electrical contact. The lead also includes a fixed
helical anchor comprising a wire member having a diameter of
between approximately 0.22 mm and approximately 0.27 mm. The wire
member distally extends away from the distal end in a helical
arrangement including an inner helical coil diameter that is
sufficient to allow the guide wire to extend through the fixed
helical anchor.
Inventors: |
Bornzin; Gene A.; (Simi
Valley, CA) ; Somogyi; Zoltan; (Simi Valley, CA)
; Theret; Didier; (Porter Ranch, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PACESETTER, INC. |
Sylmar |
CA |
US |
|
|
Family ID: |
58499228 |
Appl. No.: |
14/877728 |
Filed: |
October 7, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 2001/0585 20130101;
A61N 1/0573 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1. A left ventricular lead for tracking over a guide wire into a
coronary sinus and providing active fixation in, or adjacent to,
the coronary sinus, the guide wire being configured for coronary
sinus lead implantation and having an outer diameter defined by an
outer cylindrical surface, the lead comprising: a tubular body
comprising a proximal end, a distal end and a central lumen through
which the guide wire is extendable; a lead connector end proximally
projecting from the proximal end and comprising at least one
electrical contact; and a fixed helical anchor comprising a wire
member having a diameter of between approximately 0.22 mm and
approximately 0.27 mm, the wire member distally extending away from
the distal end in a helical arrangement including an inner helical
coil diameter defined by a radially inner curved boundary, the
inner coil diameter having a size relationship with the outer
diameter of the guide wire with the inner coil diameter being
larger than the outer diameter of the guide wire within a small
range, the size relationship positioning the radially inner curved
boundary of the wire member immediately adjacent the outer
cylindrical surface of the guide wire when the guide wire extends
through the fixed helical anchor.
2. The lead of claim 1, wherein the inner helical coil diameter is
between approximately 0.017 inch and approximately 0.019 inch.
3. The lead of claim 2, wherein the diameter of the wire member is
approximately 0.25 mm, and the inner helical coil diameter is
approximately 0.018 inch.
4. The lead of claim 1, wherein the tubular body has a size of
approximately 3 F or less.
5. The lead of claim 4, wherein the tubular body is configured to
provide approximately one-to-one torque transfer between its
proximal end and distal end under implantation conditions.
6. The lead of claim 4, wherein the tubular body is configured to
provide a torque transfer of at least approximately 65 percent
between its proximal end and distal end under implantation
conditions.
7. The lead of claim 6, wherein the torque transfer is such that a
28 degree rotation at the proximal end results in at least
approximately 13 degrees of rotation at the distal end under
implantation conditions.
8. The lead of claim 6, wherein the tubular body comprises a
polyethylene terephthalate (PET) braided quatra-filer cable
helically coiled over a polytetrafluoroethylene (PTFE) liner.
9. The lead of claim 8, wherein the tubular body further comprises
a reflowed layer of silicone rubber polyurethane co-polymer (SPC)
extending over the polytetrafluoroethylene (PTFE) liner and the
polyethylene terephthalate (PET) braided quatra-filer cable.
10. The lead of claim 1, wherein the wire member comprises a distal
tip configured such that, when the guide wire extends through the
tubular body and fixed helical anchor, an extreme distal point of
the distal tip is positioned and oriented relative to an outer
cylindrical surface of the guide wire such that the distal extreme
distal point is generally prevented from tissue cutting when the
fixed helical anchor is rotated about a longitudinal center axis of
the guide wire or the lead is tracked along the guide wire.
11. The lead of claim 10, wherein the extreme distal point is
generally tangential with the outer cylindrical surface.
12. The lead of claim 10, wherein the extreme distal point is
generally flush with the outer cylindrical surface.
13. The lead of claim 10, wherein the wire member includes a most
distal coil distally terminating in the extreme distal point of the
distal tip and including a radially inner curved boundary and a
radially outer curved boundary opposite the radially inner curved
boundary.
14. The lead of claim 13, wherein the distal tip proximally begins
on the radially outer curved boundary and distally terminates in
the extreme distal point at the radially inner curved boundary.
15. The lead of claim 13, wherein the distal tip includes a bevel
including: a proximal border on the radially outer curved boundary;
and a distal border on the radially inner curved boundary.
16. The lead of claim 15, wherein the bevel includes a curved
surface or a planar surface between the proximal border and the
extreme distal point.
17. The lead of claim 15, wherein the extreme distal point is
defined at least in part by an intersection of the radially inner
curved boundary and the bevel.
18. The lead of claim 1, further comprising a ring shaped electrode
on the tubular body and proximal the distal end, at least one of
the ring shaped electrode or the fixed helical anchor being in
electrical communication with the at least one electrical
contact.
19. The lead of claim 1, wherein the lead is quadrapolar.
20. A method of implanting a left ventricular lead in tissue of a
coronary sinus or an adjacent vascular structure with active
fixation, the method comprising: negotiating a guide wire through a
Patient cardiovascular system until a distal end of the guide wire
is located in the coronary sinus or the adjacent vascular
structure, the guide wire having an outer diameter defined by an
outer cylindrical surface; advancing a left ventricular lead over
the guide wire until a fixed helical anchor distally projecting
from a distal end of the lead is located in the coronary sinus or
the adjacent vascular structure, the fixed helical anchor having an
inner helical coil diameter defined by a radially inner curved
boundary, the inner coil diameter having a size relationship with
the outer diameter of the guide wire with the inner coil diameter
being larger than the outer diameter of the guide wire within a
small range, the size relationship positioning the radially inner
curved boundary of the fixed helical anchor immediately adjacent
the outer cylindrical surface of the guide wire when the guide wire
extends through the fixed helical anchor during the advancement,
the engagement of the fixed helical anchor with cardiovascular
system tissue being inhibited during the advancement of the lead
over the guide wire by the guide wire extending through the fixed
helical anchor during the advancement; proximally withdrawing the
guide wire from the left ventricular lead an amount sufficient to
cause the guide wire to vacate the fixed helical anchor; and
rotating the left ventricular lead to cause the vacated fixed
helical anchor to screw into the tissue of the coronary sinus or
adjacent vascular structure.
Description
FIELD OF THE INVENTION
[0001] Aspects of the present invention relate to medical apparatus
and methods. More specifically, the present disclosure relates to
implantable left ventricular leads and methods of using such
leads.
BACKGROUND OF THE INVENTION
[0002] Implantable cardiac pulse generators (e.g., pacemakers,
implantable cardioverter defibrillators (ICD), or etc.) often
include elongated medical electrical leads that can be advanced
into patient hearts. The electrical leads include electrodes to
sense electrical activity and deliver therapeutic stimulation. In
recent years, left ventricular (LV) leads are advanced into the
coronary sinus in order to position the electrodes of the leads at
left ventricular pacing sites, typically located in proximity to
the base of the left ventricle.
[0003] Some patients may have very small subclavian veins and may
require leads smaller than 6 F or 5 F to transverse the small
subclavian veins. Some patients may have complex venous anatomies
that are difficult to navigate. In order to help navigate in the
complex venous anatomies, a guide wire has been commonly used.
Although an implanter may be able to get the guide wire to the
target site, a quadrapolar LV lead generally has a large diameter
which makes it difficult for the LV lead to track a guide wire
around acute bends.
[0004] Although a variety of LV leads, along with methods for
implanting such leads, have been developed, there is still a need
in the art for developing downsized LV leads and methods of
implantation that facilitate pacing or sensing lateral and
posterial basal locations of a heart.
BRIEF SUMMARY OF THE INVENTION
[0005] Disclosed herein is a left ventricular lead for tracking
over a guide wire into a coronary sinus and providing active
fixation in, or adjacent to, the coronary sinus. The guide wire is
configured for coronary sinus lead implantation and has an outer
diameter. In one embodiment, the lead includes a tubular body
including a proximal end, a distal end and a central lumen through
which the guide wire is extendable. The lead also includes a lead
connector end proximally projecting from the proximal end and
comprising at least one electrical contact. The lead also includes
a fixed helical anchor comprising a wire member having a diameter
of between approximately 0.22 mm and approximately 0.27 mm. The
wire member distally extends away from the distal end in a helical
arrangement including an inner helical coil diameter that is
sufficient to allow the guide wire to extend through the fixed
helical anchor.
[0006] In one embodiment, the inner helical coil diameter is
between approximately 0.017 inch and approximately 0.019 inch. The
diameter of the wire member is approximately 0.25 mm, and the inner
helical coil diameter is approximately 0.018 inch. The tubular body
may have a size of approximately 3 F or less.
[0007] In one embodiment, the tubular body is configured to provide
approximately one-to-one torque transfer between its proximal end
and distal end under implantation conditions. For example, the
tubular body is configured to provide a torque transfer of at least
approximately 65 percent between its proximal end and distal end
under implantation conditions. In other words, the torque transfer
is such that a 20 degree rotation at the proximal end results in at
least approximately 13 degrees of rotation at the distal end under
implantation conditions.
[0008] In one embodiment, the tubular body includes a polyethylene
terephthalate (PET) braided quatra-filer cable helically coiled
over a polytetrafluoroethylene (PTFE) liner. The tubular body
further includes a reflowed layer of silicone rubber polyurethane
co-polymer (SPC) extending over the polytetrafluoroethylene (PTFE)
liner and the polyethylene terephthalate (PET) braided quatra-filer
cable.
[0009] In one embodiment, the wire member comprises a distal tip
configured such that, when the guide wire extends through the
tubular body and fixed helical anchor, an extreme distal point of
the distal tip is positioned and oriented relative to an outer
cylindrical surface of the guide wire such that the distal extreme
distal point is generally prevented from tissue cutting when the
fixed helical anchor is rotated about a longitudinal center axis of
the guide wire or the lead is tracked along the guide wire. In such
an embodiment, the extreme distal point may be generally tangential
with the outer cylindrical surface. The extreme distal point may be
generally flush with the outer cylindrical surface.
[0010] The wire member may include a most distal coil distally
terminating in the extreme distal point of the distal tip and
including a radially inner curved boundary and a radially outer
curved boundary opposite the radially inner curved boundary. The
distal tip proximally may begin on the radially outer curved
boundary and distally terminate in the extreme distal point at the
radially inner curved boundary. The distal tip may include a bevel
including: a proximal border on the radially outer curved boundary;
and a distal border on the radially inner curved boundary.
[0011] The bevel may include a curved surface or a planar surface
between the proximal border and the extreme distal point. The
extreme distal point may be defined at least in part by an
intersection of the radially inner curved boundary and the
bevel.
[0012] In one embodiment, the lead further includes a ring shaped
electrode on the tubular body and proximal the distal end, at least
one of the ring shaped electrode or the fixed helical anchor being
in electrical communication with the at least one electrical
contact. In one embodiment, the lead is quadrapolar.
[0013] In one embodiment, the above-described lead may be part of a
system further including the guide wire, wherein the inner helical
coil diameter is between approximately 0.002 inch and approximately
0.004 inch larger than the outer diameter of the guide wire. The
outer diameter of the guide wire may be between approximately 0.012
inch and approximately 0.018 inch or even between approximately
0.014 inch and approximately 0.016 inch, in one embodiment. The
guide wire may include a proximal handle coupled to an end of the
guide wire near the proximal end of the tubular body. The tubular
body rotates with the guide wire by rotating the proximal handle.
In one embodiment, the guide wire includes a metal and has an outer
diameter of between approximately 0.015 inch and approximately
0.016 inch, and the inner helical coil diameter is approximately
0.018 inch.
[0014] In one embodiment, the above-described lead may be part of a
system further including a pulse generator.
[0015] Also disclosed herein is a method of implanting a left
ventricular lead in tissue of a coronary sinus or an adjacent
vascular structure with active fixation In one embodiment, the
method includes: negotiating a guide wire through a patient
cardiovascular system until a distal end of the guide wire is
located in the coronary sinus or the adjacent vascular structure;
advancing a left ventricular lead over the guide wire until a fixed
helical anchor distally projecting from a distal end of the lead is
located in the coronary sinus or the adjacent vascular structure,
the engagement of the fixed helical anchor with cardiovascular
system tissue being inhibited during the advancement of the lead
over the guide wire by the guide wire extending through the fixed
helical anchor during the advancement; proximally withdrawing the
guide wire from the left ventricular lead an amount sufficient to
cause the guide wire to vacate the fixed helical anchor; and
rotating the left ventricular lead to cause the vacated fixed
helical anchor to screw into the tissue of the coronary sinus or
adjacent vascular structure.
[0016] With respect to the method disclosed herein, in one
embodiment, rotating the left ventricular lead may further include
causing the left ventricular lead to rotate with the guide wire or
about the guide wire.
[0017] With respect to the method disclosed herein, in one
embodiment, the fixed helical anchor may include a wire member
including a diameter of between approximately 0.22 mm and
approximately 0.27 mm, the wire member distally extending away from
the distal end in a helical arrangement including an inner helical
coil diameter that is sufficient to allow the guide wire to extend
through the fixed helical anchor. The inner helical coil diameter
may be between approximately 0.017 inch and approximately 0.019
inch. In one embodiment, the diameter of the wire member may be
approximately 0.25 mm, and the inner helical coil diameter is
approximately 0.018 inch. The tubular body may have a size of
approximately 3 F or less.
[0018] With respect to the method disclosed herein, in one
embodiment, the left ventricular lead may include a tubular body
configured to provide approximately one-to-one torque transfer
between its proximal end and distal end under implantation
conditions. For example, the tubular body may be configured to
provide a torque transfer of at least approximately 65 percent
between its proximal end and distal end under implantation
conditions. In other words, the torque transfer may be such that a
20 degree rotation at the proximal end results in at least
approximately 13 degrees of rotation at the distal end under
implantation conditions.
[0019] While multiple embodiments are disclosed, still other
embodiments of the present disclosure will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the disclosure. As
will be realized, the invention is capable of modifications in
various aspects, all without departing from the spirit and scope of
the present disclosure. Accordingly, the drawings and detailed
description are to be regarded as illustrative in nature and not
restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The description will be more fully understood with reference
to the following figures, which are presented as various
embodiments of the disclosure and should not be construed as a
complete recitation of the scope of the disclosure, wherein:
[0021] FIG. 1 is a diagrammatic depiction of an electrotherapy
system electrically coupled to a patient heart as shown in an
anterior view, a distal portion of a LV lead being implanted in the
CS.
[0022] FIG. 2 illustrates a LV lead that can be attached to a pulse
generator (e.g., pacemaker, implantable cardioverter defibrillator
(ICD), or etc.) and be delivered to an implantation target sit via
the use of a guide wire in accordance with embodiments of the
present disclosure.
[0023] FIG. 3 is an assembled view of the guide wire in the LV lead
of FIG. 2.
[0024] FIG. 4A is an enlarged view of the helical anchor region of
FIG. 3 with another embodiment of the helical coil including fewer
number of coils.
[0025] FIG. 4B is an enlarged view of the helical screw region of
FIG. 3 with an embodiment employing double helical coils.
[0026] FIG. 5 is an elevation view of the lead distal end as viewed
in the direction indicated by arrows 4-4 in FIG. 4A.
[0027] FIG. 6 is the same view as FIG. 5, except showing only the
most distal end termination of the helical anchor for clarity
purposes.
[0028] FIG. 7 is a schematic depiction of the medical lead being
guided along a guide wire through a subclavian vein to a left side
of a heart in accordance with embodiments of the present
disclosure.
DETAILED DESCRIPTION
[0029] The present disclosure provides implantable LV leads and
methods of implantation that facilitate stimulation of lateral and
posterior basal regions of a heart. The LV lead has a small
diameter and an active fixation configuration that allows the
distal end of the LV lead to be actively fixed at an implantation
site in the lateral and posterior basal regions of the heart. The
active fixation configuration may be in the form of an active
fixation helical arrangement with an internal diameter that closely
approximates an outer diameter of a guide wire over which the lead
distal end is tracked to the implantation target site, the close
tolerance between the diameters of the active fixation arrangement
and the guide wire preventing the active fixation arrangement from
snagging vasculature or heart tissue premature to the active
fixation arrangement being purposely fixed to tissue in the course
of the lead being implanted at an implantation target site. The LV
lead includes a proximal end that can be connected to a pulse
generator (e.g., pacemaker, implantable cardioverter defibrillator
(ICD), or etc.). The LV lead also includes electrodes at its distal
end to sense electrical signals in the heart tissue and deliver
electrical pulses from the pulse generator to the heart tissue of
the lateral and posterior basal regions in the heart.
[0030] The present disclosure provides a downsized LV lead (e.g. 3
F LV lead) with an active fixation configuration at its distal end.
By using the active fixation to attach the LV lead to the tissue at
a target implant site, the LV lead can be assured to remain at the
target implant site. The active fixation can allow the LV lead to
have a reduced size as compared to the size of passive fixation LV
leads. Specifically, passive fixation may require a relatively
stiff LV lead for stabilization at a target implant site. Such lead
stiffness may not be obtained for a LV lead with reduced diameter.
For example, to stabilize a LV lead in remaining at the target
implant site, passive fixation may use a known "S-shaped"
structure. As the LV lead is downsized, the stiffness of the LV
lead may decrease with the fourth power of the radius of the LV
lead. Therefore, the lateral forces of the "S-shaped" structure
exerted against the vessel walls of a vein by a downsized 3 F lead
are dramatically lower than the forces exerted by a larger 5 F
lead. Also, it may not be desirable to add a stiffening wire in the
lead body because the stiffening wire may take more space and may
present a risk of perforation should the lead body fail. The active
fixation may also allow the LV lead to be positioned anywhere in
the heart, unlike passive fixation as made possible via an
"S-shaped" lead body structure or as made possible via passive
fixation tines.
[0031] The LV lead may include an elongated tubular body having a
distal end and a proximal end. The LV lead may also include an
active fixation configuration in the form of a hollow helical screw
or helical anchor fixedly attached to the distal end of the tubular
body for active fixation to the coronary sinus or adjacent vascular
structures or heart tissue. The LV lead may also include a lead
connector attached to the proximal end of the tubular body for
connecting to a pulse generator.
[0032] As already noted, on account of the configuration of the
helical anchor relative to the configuration of the guide wire over
which the lead is tracked through the patient, the helical anchor
may be protected from inadvertently snagging patient tissue as the
lead is tracked over the guide wire to reach to the target implant
site. The tubular body of the LV lead can be turned or rotated with
the guide wire or around the guide wire to allow the helical anchor
to engage the tissue. The guide wire may include a proximal handle
at a proximal end such that the guide wire may be turned by using
the proximal handle and to cause the tubular body of the LV lead to
rotate with the guide wire.
[0033] A general, non-limiting discussion is now provided regarding
some of the features and deployment characteristics common among
the various lead and implantation embodiments disclosed herein.
FIG. 1 is a diagrammatic depiction of an electrotherapy system 10
electrically coupled to a patient heart 15 as shown in an anterior
view. As shown in FIG. 1, the system 10 includes an implantable
pulse generator 20 (e.g., pacemaker, implantable cardioverter
defibrillator (ICD), or etc.) and one or more (e.g., three)
implantable medical leads 5, 6, 7 electrically coupling the patient
heart 15 to the pulse generator 20. While the following discussion
will focus on the configuration and implantation of the left
ventricular (LV) lead 5 extending into the coronary sinus (CS) 21
via the coronary sinus ostium (OS) 22, it should be remembered that
the system 10 may employ only the LV lead 5 or the LV lead 5 in
conjunction with other leads, such as, for example, a right
ventricular (RV) lead 6 and/or right atrial (RA) lead 7. The RV and
RA leads 6, 7 may employ pacing electrodes 25, sensing electrodes
30 and shock coils 35 as known in the art to respectively provide
electrical stimulation to the right ventricle 40 and right atrium
45 of the heart 15.
[0034] As can be understood from FIG. 1, which shows an anterior
view of the patient heart 15, the CS 21 extends generally from the
OS 22 and, further, posterior to anterior until transitioning into
the great cardiac vein or coronary vein 47, which then extends in a
generally inferior direction along the anterior region of the left
ventricle (LV) 48. In extending generally posterior to anterior
from the OS 22 until transitioning into the great cardiac vein 47,
the CS 21 is inferior to the left atrium (LA) 49 and superior to
the LV 48.
[0035] As indicated in FIG. 1, in most embodiments of the LV lead 5
disclosed herein, the distal portion 50 of the LV lead 5 may extend
into the great cardiac vein 47 and be implanted in vein 47. The
distal portion 50 may also be implanted in the CS 21 or vein
branches extending off of the CS 21. The distal portion 50 of each
embodiment of the LV lead 5 disclosed herein is configured to
facilitate implanting in the CS 21 or vein 47, more particularly,
in the lateral and posterior basal region of the heart. Because of
its active fixation capability and the smallness of its active
fixation anchor, as described below, the distal end of the LV lead
5 can be actively affixed to the LV heart wall or the vessel wall
of the CS 21, great coronary vein 47 or other related vasculature
walls with little risk from the active fixation.
[0036] FIG. 2 illustrates a LV lead 5 that can be attached to a
pulse generator 20 and be delivered to an implantation target sit
via the use of a guide wire in accordance with embodiments of the
present disclosure. As shown, a LV lead 5 includes an elongated
tubular body 92 that includes a proximal end 93, a distal end 97
opposite to the proximal end 93, and an elongated central lumen 91
extending between the proximal end 93 and the distal end 97. The
central lumen 91 may be generally in a cylindrical shape. The
central lumen 91 allows a guide wire 86 to pass through from the
proximal end 93 to the distal end 97.
[0037] The LV lead 5 also includes a hollow helical anchor 90
fixedly attached to the distal end 97 of the tubular body 92. The
helical anchor 90 may be engaged with the heart wall or vascular
tissue and provide active fixation to remain at a target or desired
implant site associated with LV implantation. More details of the
helical anchor 90 will be illustrated in FIGS. 3-6 and described
later.
[0038] The LV lead 5 may also include four ring shaped electrodes
88A-D outside the tubular body 92 near the distal end and are
generally flush with the outer surface of the tubular body 92. The
ring shaped electrodes 88A-D may be spaced apart from each other.
The distance between the electrodes may vary. The three electrodes
88A-C are near the distal end 97 of the tubular body 92 while ring
shaped electrode 88D may be positioned at the distal end 97 of the
tubular body 92 and is electrically connected to the helical anchor
90. Each ring electrode 88A-D and the helical anchor 90 may be
formed of a biocompatible electrically conductive metal (e.g.,
stainless steel, gold platinum, platinum-iridium alloy, etc.) and
can server as an electrode for pacing (e.g., delivering stimulation
to the heart) and/or sensing electrical activities from the
heart.
[0039] A guide wire 86 may be used for assisting the LV lead to
reach a target implant site and to inhibit the engagement of the
helical anchor with cardiovascular system tissue during the
advancement of the LV lead to the target implant site. The guide
wire 86 may have a distal end 84, a proximal end 82, and an
elongated body having an outer surface 120 extending between the
distal end 84 and the proximal end. The guide wire may be in a
general cylindrical shape. A proximal handle 80 may be connected to
the proximal end 82 of the guide wire to assist with rotating the
guide wire by hand. The guide wire 86 may be configured to be
inserted into the LV lead 5 from a lead connector end 95 of the
proximal end 93 of the tubular body 92 and to pass through the
central lumen 91 to extend beyond the distal end 97 of the tubular
body 92, thereby passing through the helical anchor 90 to extend
beyond the most distant coil of the helical anchor 90, as reflected
in FIG. 3 discussed below.
[0040] The LV lead 5 may further include the lead connector end 95
proximally projecting from the proximal end 93 of the tubular body
92. The lead connector end 95 may include ring contacts 94A-C that
are positioned between inner seals 96A and 96D. The inner seals 96A
and 96D may be used to isolate the ring contacts from any body
fluids. Additional outer seals 96B and 96C may be positioned at a
further distance from the ring contacts 94A-C than the inner seals
96A and 96D to further prevent the body fluids from entering the
space between the inner seals 96A and 96D. These seals may be
formed of insulating materials, such as biocompatible polymers or
rubbers. The lead connector end 95 may also include a hollow pin
contact 94D proximally projecting from the outer seal 96C and
through which the guide wire may be inserted through the connector
end 95 and into the central lumen 91 of the lead body 92. These
contacts 94A-D are in electrical communication with the respective
ring shaped electrodes 88A-D near the distal end 97. For example,
these contacts 94A-D are electrically coupled to respective
conductors (e.g., coiled conductors, or cable or stranded
conductors as known in the art) that extend through the lead from
the contacts 94A-D to the ring shaped electrodes 88A-D.
[0041] The lead connector end 95 is configured to be inserted into
a receptacle 99 of the pulse generator 20 to so the contacts 94A-D
can electrically couple with the circuitry of the pulse generator
20, thereby allowing the pulse generator to sense cardiac
electrical signals and administer electrotherapy via the lead. The
lead connector end 95 includes a hollow central portion configured
to allow the guide wire 86 to pass through the lead connector end
and into the lumen of the lead body, as already mentioned above.
The lead connector end 95 is fixedly attached to the tubular body
92 near the proximal end 93 of the tubular body 92.
[0042] Quadrapolar electrodes are commonly used in LV leads. The
quadrapolar electrodes may be used to sense signals from the heart
or deliver electrical stimulation to pace the heart by using an
electrical pulse generator or pace maker 20 as shown in FIG. 2. In
some embodiments, the electrodes may be ring shaped, such as shown
in FIG. 2, or other shapes. The ring shaped electrodes may be
coaxial with the tubular body 92. The most distal ring shaped
electrode 88D at the distal end of the tubular body 92 may be
connected to the helical screw 90, which may provide therapy to the
heart along with the most distal ring shaped electrode. The
electrical signals may along the conductors of the lead body
between the electrodes 88A-D and the pulse generator 20, and vice
versa, in the course of electrotherapy being administered to the
cardiac tissue of the LV. While, a quadrapolar electrode
arrangement is depicted in the figures, it will be appreciated by
those skilled in the art that the electrodes may alternatively be
of a unipolar, bipolar, or multipolar electrode arrangement.
[0043] FIG. 3 is an assembled view of the guide wire 86 in the LV
lead 5 of FIG. 2. As shown, system 300 includes the guide wire 86
inserted into the tubular body 92 of the LV lead 5 from the lead
connector end 95. The guide wire 86 passes through the lead
connector end 95, the central lumen 91 of the tubular body 92, and
also the helical anchor 90, the guide wire extending beyond the
most distant coil 85 of helical anchor 90. This guide wire 86
extending beyond the helical anchor may help protect the helical
anchor 90 from engaging patient cardiovascular tissue during the
advancement of the LV lead to reach a target implant site. In other
words, the helical screw or anchor 90 is protected from snagging
the patient cardiovascular tissue during tracking of the lead
distal end 97 through the vasculature of the patient by using the
guide wire 86 in a manner such that the guide wire 86 passes
through the helical screw 90 in close tolerances and extends beyond
the distal end 97 of the LV lead 5 and the helical anchor 90. As a
result, the guide wire 86 interferes with the helical anchor 90
engaging the cardiovascular tissue as the LV lead 5 is
advanced.
[0044] The helical anchor 90 includes a few turns of the coil 85
including the most distant turn that terminates. The coil is
arranged in a helical configuration around a longitudinal axis 95
of the tubular body 92. As discussed in greater detail below, the
coil 85 has an inner diameter that is only slightly larger than an
outer diameter of the guide wire 86 such that the guide wire
prevents the helical anchor from engaging or damaging cardiac
tissue in the process of the lead being tracked over the guide wire
in the course of the lead being implanted in the patient. Once the
guide wire is withdrawn from the confines of the helical anchor and
the helical anchor is placed against cardiac or other patient
tissue, the lead may be rotated around its longitudinal axis 95 to
cause the helical anchor 90 to rotate around the longitudinal axis
95 and screw into the tissue.
[0045] An enlarged view of the helical anchor 90 and distal end of
the lead is shown in FIGS. 4A and 4B, but with different
embodiments of the helical anchor 90. As shown in FIG. 4A, the
helical anchor may have one full turn of the coil 85 instead of a
few turns of the coil 85 as shown in FIG. 3. Similar to the helical
anchor illustrated in FIG. 3, the helical anchor of FIG. 4A may be
in the form of a single helical coil arrangement formed from a
single helically wound member (e.g., a helically wound wire). The
most distal ring shaped electrode 88D may be positioned on the
tubular body 92 near the distal end 97 of the tubular body 92, and
may be electrically connected to the helical anchor 90. The ring
shaped electrode 88D may be generally flush with the tubular body
92.
[0046] As shown in FIG. 4B, the helical anchor 90 may include
double helical coils 87 and 85 that are wound in opposite
directions and may be 180.degree. out of phase. Both helical coils
87 and 85 may be electrically connected to the ring shaped
electrode 88D which is on the tubular body 92. The double helical
coils may provide better engagement with the tissue than a single
helical coil. It will be appreciated by those skilled in the art
that the helical anchor may vary in coil configuration or shape. In
some embodiments, the helical anchor may not serve as an electrode,
but instead solely functions as a fixation device.
[0047] The lead may be caused to rotate about its longitudinal axis
via rotation of the guide wire 86 extending through the lead. The
lead may be caused to rotate about its longitudinal axis by a
rotational force being exerted on the proximal end of the lead. The
lead tubular body 92 is configured to provide approximately
one-to-one torque transfer between the proximal end 93 and distal
end 97 of the tubular body 92 under implantation conditions. For
example, in some embodiments, the torque transfer may be at least
approximately 65 percent between its proximal end and distal end
under implantation conditions. For example, the torque transfer may
allow a 20 degree rotation at the proximal end resulting in at
least approximately 13 degrees of rotation at the distal end under
implantation conditions.
[0048] The tubular body 92 may have a size of approximately 3 F or
less such that the LV lead can be small enough used in patients
with very small veins. This size is significantly smaller than
conventional 5 F or 6 F LV lead.
[0049] In one embodiment, to facilitate the above-described torque
transfer characteristics, the tubular body 92 may be formed of a
biocompatible polymer which has relatively high stiffness such that
the tubular body can provide one-to-one torque transfer or at least
65 percent torque transfer, as discussed above. The polymers may
include, but are not limited to, a polyethylene terephthalate (PET)
braided quatra-filer cable helically coiled over a
polytetrafluoroethylene (PTFE) liner. In a particular embodiment,
the tubular body may be formed of a reflowed layer of silicone
rubber polyurethane co-polymer (SPC) extending over the
polytetrafluoroethylene (PTFE) liner and the polyethylene
terephthalate (PET) braided quatra-filer cable. The tubular body 92
may be constructed by using DACRON.RTM. braided quatra-filer coiled
cable over a TEFLON.RTM. liner, such that the LV lead 5 can
transfer torque from a proximal end to the distal end as described
above. For further discussion of lead body configurations useful in
achieving the above-described torque transfer performance, see U.S.
patent application Ser. No. 14/080,676, which was filed Nov. 14,
2014, is entitled "MRI Compatible Implantable Lead" and claims
priority to U.S. Application No. 61/784,985, which was filed Mar.
14, 2013, these applications being incorporated by reference herein
in their entireties.
[0050] Referring to FIG. 3 again, the tubular body 92 is coaxial
with the guide wire 86 prior to being implanted into a patient
cardiovascular system. The tubular body 92 and the guide wire 86
may have interference when implanted such that the tubular body 92
may be caused to rotate with the guide wire 86 or around the guide
wire 86. When the guide wire 86 is rotated by the proximal handle
80, the tubular body 92 may rotate with the guide wire 86 to
transfer the torque from the proximal end 82 to the helical anchor
90 that is fixedly attached to the distal end of the tubular body
92. With the transferred torque, the helical screw 90 may rotate to
attach to the tissue, such as coronary sinus 21. To verify if the
helical screw 90 is fixedly attached to the tissue, an implanter
may gently tug on the LV lead 5 to verify the active fixation.
Alternatively, instead of employing the guide wire to bring about
rotation of the lead body, the lead connector end 95 may be grasped
and rotated to bring about the rotation of the lead body, and by
extension, the helical anchor. Alternatively, the lead and guide
wire may both be grasped to apply rotation to the assembled devices
as a whole or individually in a vice versa manner to bring about
the rotation of the lead body used to screw the helical anchor into
the tissue.
[0051] The helical screw 90 and the guide wire 86 may be configured
to have a tolerance to allow the guide wire 86 to easily extend
through the helical screw 90 and to be smoothly pulled back to
vacate the helical screw 90 without resistance or friction. In some
embodiments, the inner diameter of one full turn of the helical
coil, also referred to as the inner helical coil diameter, may be
between approximately 0.002 inch and approximately 0.004 inch
larger than the outer diameter of the guide wire. The outer
diameter of the guide wire 86 may be between approximately 0.015
inch and approximately 0.016 inch. The inner helical coil diameter
may be between approximately 0.017 inch and approximately 0.019
inch. In a particular embodiment, the inner helical coil diameter
may be approximately 0.018 inch. The helical screw 90 may be formed
of biocompatible metal or metal alloys, such as platinum, platinum
iridium alloy, MP35N, or stainless steel, and may act as an anchor
electrode.
[0052] For a detailed discussion of the structural relationship
between the guide wire 86 and the helical anchor 90 in the vicinity
of the tip 110 of the helical anchor 90, reference is now made to
FIGS. 5 and 6, wherein FIG. 5 is an elevation view of the lead
distal end as viewed in the direction indicated by arrows 4-4 in
FIG. 4A, and FIG. 6 is the same view as FIG. 5, except showing only
the most distal end termination of the helical anchor 90 for
clarity purposes. As illustrated in FIGS. 5 and 6, the most distal
turn of the coil 85 of the helical anchor 90 includes a radially
inner curved boundary 106 and a radially outer curved boundary 104
opposite the radially inner curved boundary 106. The most distal
turn of the coil 85 of the helical anchor 90 distally terminates in
the tissue penetrating tip 110.
[0053] As best understood from the enlarged view of the tip 110
depicted in FIG. 6, the tip 110 proximally begins on the radially
outer curved boundary 104 and distally terminates in a point 108 at
the radially inner curved boundary 106, the point 108 forming the
extreme distal termination of the tissue penetrating tip 110. The
tip 110 can be seen to include a grind, taper surface or bevel 112
that has a proximal border 100 on the radially outer curved
boundary 104 and a distal border 108 in the form of sharp point on
the radially inner curved boundary 106. In one embodiment, the
bevel 112 may have a curved surface between the proximal border 100
and the point 108. In other embodiments, the bevel 112 may have a
straight, flat or planar surface between the proximal border 100
and the point 108. The point 108 is defined at least in part by an
intersection of the radially inner curved boundary 106 and the
bevel 112.
[0054] As can be understood from FIGS. 4A and 5, the coil or wire
member 85 of the helical anchor 90 includes a distal tip 110 which
is configured such that, when the guide wire 86 extends through the
tubular body 92 and the fixed helical anchor 90, the radially inner
curved boundary 106 is immediately adjacent the outer cylindrical
surface 120 of the guide wire, and the extreme distal point 108 of
the tip 110 is positioned immediately next to and oriented towards
the outer cylindrical surface 120 of the guide wire 86. These
arrangements help prevent the tip 110 from cutting or otherwise
engaging tissue when guide wire extends through the coils of the
helical anchor and the helical anchor 90 is rotated about the
longitudinal center axis 95 of the guide wire 86 or the LV lead 5
which is tracked along the guide wire 86. To avoid cutting the
tissue during advancement of the LV lead 5 over the guide wire 86,
the distal tip 110 of the helical anchor is generally tangential
with the outer cylindrical surface 120 of the guide wire 86. Also,
the distal tip 110 is generally flush with the outer cylindrical
surface 120 of the guide wire 86 to avoid the cutting during the
lead advancement.
[0055] FIG. 7 is a schematic depiction of the medical lead 5 being
guided along the guide wire 86 through a subclavian vein 130 to a
left side of a heart 15. As illustrated in FIG. 7, the distal end
84 of the guide wire 86 is advanced ahead of the lead 5 through the
superior vena cava (SVC) 132 and into the right atrium region 134.
The guide wire 86 is further advanced ahead of LV lead 5 into the
coronary sinus (CS) 21 via the coronary sinus ostium (OS) 22 via,
as indicated by arrow C. On account of the configuration of the
helical anchor tip, as described above, and, as also described
above, the complementary configurations of the guide wire and
helical anchor and the way in which they interact to prevent the
helical anchor point 108 from engaging tissue when the guide wire
extends through the coils of the helical anchor, the helical anchor
can be exposed as the lead tracks along the guide wire from the SVC
132 and into the CS 21, and the helical anchor point 108 will not
catch or snag on cardiac or vascular structures along the way to
the implant site in the CS 21 or coronary vein 47. While the lead 5
is being guided along guide wire 86, the lead 5 itself may also be
rotated to further prevent the helical anchor point 108 from
catching or snagging. For example, if the helical anchor point 108
requires clockwise rotation for fixation at an implant site,
counter-clockwise rotation of the lead 5 may reduce the likelihood
of catching or snagging.
[0056] During a LV lead implantation procedure, which may be
visualized via X-ray fluoroscopy, the distal end of the LV lead may
be implanted at a target implant site in the coronary sinus 21 or
adjacent vascular structure. To deliver the lead distal end to the
target implant site, the guide wire 86 may be negotiated through
the patient cardiovascular system until the distal end 84 of the
guide wire 86 reaches the target implant site. The LV lead 5 may be
then advanced over the guide wire 86 until the helical anchor 90 is
located in the coronary sinus 21 or the adjacent vascular
structure, such as, for example, the coronary vein 47. Then, the
guide wire 86 may be proximally withdrawn from the LV lead 5
sufficiently to vacate the helical anchor 90. The proximal end 93
of the LV lead 5 may be rotated to cause the vacated fixed helical
anchor 5 to screw into the tissue at the target implant site. The
proximal end 93 of the LV lead 5 may be rotated by causing the LV
lead to rotate with the guide wire 86 or about the guide wire. For
example, the proximal end 82 of the guide wire 86 may be rotated by
using the proximal handle 80 to cause the LV lead to rotate with
the guide wire, such that the vacated helical anchor can screw into
the coronary sinus 21. Alternatively, the distal end of the lead
may have a rotational force directly applied to it to cause the
lead body to rotate about its longitudinal axis, thereby providing
the rotation that causes the helical anchor body to screw into the
tissue.
[0057] The size and gauge of the active fixation anchor 90
disclosed herein is very small and the process of active fixation
in the vein will not result in blood leakage as its resulting very
small hole in the vein wall will be sealed off by a platelet plug
that readily forms to fill the small hole, thereby preventing any
bleeding and working to maintain hemostasis. For this reason, the
diameter of the wire used to form the coils of the helical anchor
90 disclosed herein may be very small, ranging between
approximately 0.22 mm and approximately 0.27 mm such that the
helical anchor may pierce a very small hole or perforation when
placed in the vein during active fixation. In a particular
embodiment, the wire forming the coils of the helical anchor 90
disclosed herein may have a diameter on the order of 0.25 mm which
is about the size of a 31 gauge hypodermic needle.
[0058] The downsized LV lead provides many benefits including, for
example, being able to implant a lead in a patient with small veins
or complex venous anatomies, reducing implantation operation time,
and improved tracking as compared to larger diameter quadrapolar
leads. The benefits of using the downsized LV lead may also include
precisely placing the LV lead at targeted implant sites, which may
improve patient outcomes. For example, the basal LV pacing may have
better results by precisely placing the LV leads at targeted
implant sites. The downsized LV lead may be used to assist
implanters in rapidly positioning the LV lead or guide wire at
targeted implant sites and thus help implant times and reduce the
exposure to X-rays.
[0059] The foregoing merely illustrates the principles of the
invention. Various modifications and alterations to the described
embodiments will be apparent to those skilled in the art in view of
the teachings herein. It will thus be appreciated that those
skilled in the art will be able to devise numerous systems,
arrangements and methods which, although not explicitly shown or
described herein, embody the principles of the invention and are
thus within the spirit and scope of the present invention. From the
above description and drawings, it will be understood by those of
ordinary skill in the art that the particular embodiments shown and
described are for purposes of illustrations only and are not
intended to limit the scope of the present invention. References to
details of particular embodiments are not intended to limit the
scope of the invention.
* * * * *