U.S. patent application number 14/324407 was filed with the patent office on 2014-10-30 for apparatus for subcutaneous electrode insertion.
The applicant listed for this patent is Cameron Health, Inc.. Invention is credited to Michael Ko, Duane Tumlinson.
Application Number | 20140324068 14/324407 |
Document ID | / |
Family ID | 36575406 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140324068 |
Kind Code |
A1 |
Ko; Michael ; et
al. |
October 30, 2014 |
APPARATUS FOR SUBCUTANEOUS ELECTRODE INSERTION
Abstract
Devices and methods for electrode implantation. A first
embodiment includes an electrode insertion tool adapted to tunnel
through tissue and attach, at its distal end, to a lead, such that
the lead may be pulled into the tunneled space as the electrode
insertion tool is removed. Additional embodiments include methods
for inserting electrode/lead assemblies, including a method wherein
an insertion tool is first used to tunnel through tissue, then to
pull an electrode/lead into the tunneled space. In a further
embodiment the insertion tool is next used, with a splittable
sheath disposed thereon, to create an additional path into tissue,
after which the insertion tool is removed, leaving the sheath in
place; a lead is inserted to the sheath, and, finally, the
splittable sheath is removed over the lead.
Inventors: |
Ko; Michael; (Mission Viejo,
CA) ; Tumlinson; Duane; (San Clemente, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cameron Health, Inc. |
St. Paul |
MN |
US |
|
|
Family ID: |
36575406 |
Appl. No.: |
14/324407 |
Filed: |
July 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13436438 |
Mar 30, 2012 |
8801729 |
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14324407 |
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12698627 |
Feb 2, 2010 |
8157813 |
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13436438 |
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11006291 |
Dec 6, 2004 |
7655014 |
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12698627 |
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Current U.S.
Class: |
606/129 |
Current CPC
Class: |
A61N 1/056 20130101;
A61M 25/0668 20130101; A61N 1/05 20130101 |
Class at
Publication: |
606/129 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1. A tool for inserting a lead electrode assembly subcutaneously,
the tool comprising: a handle; and a shaft having a proximal end
and a distal end, the shaft being secured near its proximal end to
the handle and including an attachment feature near its distal end
for attaching to a lead electrode assembly, the distal end being
shaped for advancement through tissue; wherein: the shaft further
defines a lumen extending therein to a distal infusion port; the
attachment feature is a suture hole adapted to receive a suture
therethrough and configured to allow a suture to be used to secure
the tool to a lead for insertion of the lead into the body of a
patient; and the distal infusion port opens into the suture
hole.
2. The tool of claim 1, wherein the shaft is a rigid shaft and is
generally straight distal of the handle.
3. The tool of claim 1, wherein the shaft is a rigid shaft and
includes a curved portion distal of the handle, the distal end of
the rigid shaft having an axial direction that is at an angle with
respect to an axial direction of the handle, the angle being
between about 30 degrees and about 90 degrees.
4. The tool of claim 3, wherein the angle is about 75 degrees.
5. The tool of claim 1, wherein the shaft is a rigid shaft and
comprises an elongate metallic tubular member having an offset
curve near its proximal end, the handle being secured over the
offset curve.
6. A lead electrode assembly insertion kit comprising: a lead
insertion tool comprising a handle; and a shaft having a proximal
end and a distal end, the shaft being secured near its proximal end
to the handle and including an attachment feature near its distal
end for attaching to a lead electrode assembly, the distal end
being shaped for advancement through tissue; wherein: the shaft
further defines a lumen extending therein to a distal infusion
port; the attachment feature is a suture hole adapted to receive a
suture therethrough and configured to allow a suture to be used to
secure the tool to a lead for insertion of the lead into the body
of a patient; and the distal infusion port opens into the suture
hole; and a splittable sheath having a longitudinal splitting line,
the sheath defining a lumen sized to receive the tool.
7. The kit of claim 6 wherein the lead insertion tool is configured
such that the shaft is a rigid shaft and is generally straight
distal of the handle.
8. The kit of claim 6 wherein the lead insertion tool is configured
such that the shaft is a rigid shaft and includes a curved portion
distal of the handle, the distal end of the rigid shaft having an
axial direction that is at an angle with respect to an axial
direction of the handle, the angle being between about 30 degrees
and about 90 degrees.
9. The kit of claim 8 wherein the lead insertion tool is configured
such that the angle is about 75 degrees.
10. The kit of claim 6 wherein the lead insertion tool is
configured such that the shaft is a rigid shaft and comprises an
elongate metallic tubular member having an offset curve near its
proximal end, the handle being secured over the offset curve.
11. The kit of claim 6 wherein the suture hole defines lateral
openings aligned to receive a suture.
12. The tool of claim 1 wherein the suture hole defines lateral
openings aligned to receive a suture .
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/436,438, filed Mar. 30, 2012, published as
US 2012-0191106 A1, which is a continuation of U.S. patent
application Ser. No. 12/698,627, filed Feb. 2, 2010, published as
US 2010-0137879 A1, and titled APPARATUS AND METHOD FOR
SUBCUTANEOUS ELECTRODE INSERTION, now issued as U.S. Pat. No.
8,157,813, which is a continuation of U.S. patent application Ser.
No. 11/006,291, filed Dec. 6, 2004, now U.S. Pat. No. 7,655,014 and
titled APPARATUS AND METHOD FOR SUBCUTANEOUS ELECTRODE INSERTION,
the entire disclosure of which is incorporated herein by
reference.
FIELD
[0002] The present invention is related to the field of medical
treatments including electrode implantations. More particularly,
the present invention is related to the field of electrode
implantation or insertion for cardiac treatments.
BACKGROUND
[0003] The use of implantable pacing and defibrillation devices to
treat or prevent various cardiac problems has become relatively
widespread. Several difficulties with such treatments relate to
placement and durability of electrodes. Typically, well practiced,
careful and gentle maneuvers are required during insertion to avoid
breaking the leads and/or electrodes. Once placed, leads may
fracture after being subjected to repeated stresses as the heart
beats and the patient moves. Leads and electrodes may also migrate
from their desired position.
[0004] For transvenous implantation, a lead is typically introduced
by advancing it through a vein to a location in or near the heart
with the aid of fluoroscopy. The lead is then anchored to heart
tissue or a passive anchor mechanism, such as a tine, is utilized
to prevent the lead from moving. The heart tissue will tend to form
around the lead, attenuating sensed signals as well as altering
pacing and/or defibrillating thresholds. Because implantation
requires traversing the vasculature as well as placement and
anchoring within the heart, many problems can arise.
[0005] Many lead insertion techniques push a lead into place into
tissue or through the vasculature. Pushing the lead stresses the
lead and can cause lead failure. With vascular implantations, the
pathway is defined but is subject to constrictions and tight turns.
Non-vascular implantation calls for tunneling through existing
tissue. While extra stiffness may help with lead insertion and aid
accurate lead placement, stiffer leads create their own problems
with migration, perforation, and fracture. As stiffness increases,
the ability of the lead to inadvertently perforate tissue rises.
Further, with extra stiffness, the lead does not rest in place
during muscle movement, tending to increase the size of any
associated fibroid, and potentially leading to migration.
SUMMARY
[0006] The present invention, in a first embodiment, includes a
tool for implanting a lead electrode assembly. The tool may include
a handle and a relatively stiff shaft having a proximal end and a
distal end, with the handle secured to the proximal end of the
shaft. The distal end of the shaft includes an attachment feature
which can be used to attach to a lead electrode assembly. The
attachment feature, in use, allows the tool to be secured to the
lead electrode assembly after it is advanced through tissue. Once
so secured, the tool enables pulling or pushing of the lead
electrode assembly through the portion of tissue that has already
been tunneled by the tool.
[0007] The shaft may also define a lumen extending distally from a
port or hub (such as a Luer hub) in the handle. The shaft may then
include a fluid infusion port for infusing a fluid forced through
the lumen into tissue during an implantation procedure. In an
illustrative method embodiment, the fluid infusion port and lumen
are used to infuse a local anesthetic such as lidocaine during an
implantation.
[0008] The attachment feature may take the form of a suture hole
allowing a suture to be passed therethrough. In a preferred
embodiment, the fluid infusion port opens into a suture hole. The
shaft may be straight, may include a curve, or may define an arc of
curvature. In one embodiment, the shaft is provided with a
curvature that mimics the curvature of a patient's lower ribcage.
The shaft may also be shapeable such that a user can adapt the
shaft to the shape of a selected portion of anatomy such as a
patient's ribcage.
[0009] In another embodiment, an electrode insertion tool kit is
provided, the tool kit including a tool for inserting an electrode
and a splittable sheath for use in conjunction with the tool. The
tool may have one or more of the features noted above. The
splittable sheath is preferably sized to snugly fit over the tool.
The kit may also include more than one insertion tool, one being
straight and one having a curved shape, as well as an infusion
tubing set for coupling to the one or more insertion tools, and a
shaping tool for re-shaping or modifying the shape of an insertion
tool.
[0010] Further embodiments include methods for inserting electrodes
and leads to a patient subcutaneously. In one such embodiment,
first and second incisions are made at spaced apart locations. An
insertion tool having proximal and distal ends is inserted via the
first incision and advanced subcutaneously toward the second
incision. The distal end of the insertion tool may be passed out
through the second incision. An electrode/lead assembly is then
attached to the distal end of the insertion tool, and the insertion
tool is withdrawn via the same path it was inserted through. As the
insertion tool is withdrawn, the electrode/lead assembly is pulled
subcutaneously into the patient. An alternative embodiment does not
include passing the distal end of the insertion tool out of the
second incision, instead only passing the distal end proximate the
incision such that the electrode/lead assembly may be attached
thereto.
[0011] In a further embodiment, the insertion tool is completely
withdrawn through the first incision until the portion of the
electrode/lead assembly connected to the insertion tool is pulled
through the first incision. Then the insertion tool is inserted via
the first incision and advanced subcutaneously in a direction
different from the direction of the second incision. Preferably,
the insertion tool is advanced in a direction that is at a
significant angle with respect to a line along which the first and
second incisions lie. The insertion tool is then removed and the
electrode/lead assembly advanced through the path defined by the
insertion tool.
[0012] In yet a further embodiment, the insertion tool, at least
during the second insertion through the first incision, is inserted
with a sheath placed thereover. Once the insertion tool and sheath
are inserted to a desired extent, the insertion tool is removed,
leaving the sheath in place. Then the electrode/lead assembly is
inserted into the sheath to a desired extent. Finally, the sheath
is removed. Preferably the sheath includes a line of axial
weakness, or is a splittable sheath, so that it can be removed over
the electrode/lead assembly without damaging or moving the
assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates in perspective view an electrode
insertion tool kit including several components;
[0014] FIGS. 2A-2B show, in perspective and section views, a
straight electrode insertion tool;
[0015] FIGS. 3A-3B show, in perspective and section views, a curved
electrode insertion tool;
[0016] FIGS. 4A-4C show detailed section views of an electrode
insertion tool handle;
[0017] FIGS. 5A-5B show, in perspective and section views, details
of an electrode insertion tool tip;
[0018] FIGS. 6A-6C show perspective and alternative detail views of
a lead electrode assembly;
[0019] FIG. 7 shows a perspective view of an insertion tool bending
device;
[0020] FIG. 8 shows a perspective partial view of an infusion
tubing set;
[0021] FIGS. 9A-9B show, in combination and alone, an insertion
tool with a splittable sheath and a splittable sheath by
itself;
[0022] FIG. 10 shows a patient illustrating relative positions for
illustrative incisions;
[0023] FIGS. 11A-11J show an illustrative method of electrode
insertion; and
[0024] FIGS. 12A-12B illustrate several aspects of different sensor
configurations.
DETAILED DESCRIPTION
[0025] The following detailed description should be read with
reference to the drawings. The drawings, which are not necessarily
to scale, depict illustrative embodiments and are not intended to
limit the scope of the invention.
[0026] It should be noted that the terms "lead" and "lead electrode
assembly" as used herein carry distinct meanings, with a lead
electrode assembly being a lead and electrode coupled together.
U.S. patent application Ser. No. 09/940,377 to Bardy et al., now
U.S. Pat. No. 6,866,044, is incorporated herein by reference. Bardy
et al. suggest several methods for insertion of a defibrillator
device including a subcutaneous canister and electrode(s), and
explain additional details of subcutaneous defibrillation devices
and methods.
[0027] FIG. 1 illustrates in perspective view a lead electrode
assembly insertion tool kit including several components. The kit
10 includes a number of items, including a straight insertion tool
20, a curved insertion tool 40, a bending tool 100 and an infusion
tubing set 110. The kit 10 may further include a splittable sheath
(not shown) such as that illustrated in FIGS. 9A-9B. In several
illustrative embodiments, the insertion tools 20, 40 include
elongate shafts made of stainless steel tubes, with plastic
handles, although other materials may be used as desired for either
portion. The infusion tubing set 110 will often include a flexible
polymeric tubular member, although this is not required. The
bending tool 100 may be used to adjust the shape of the insertion
tools 20, 40, although again this is not required. Features of each
of these elements are further explained below.
[0028] FIGS. 2A-2B show, in perspective and section views, a
straight electrode insertion tool. Referring to FIG. 2A, the tool
20 is generally straight distal of its handle 26, and includes a
shaft portion 22 that is preferably stiff enough to provide
pushability to a distal end 24 for creating a path through tissue.
In several embodiments, a relatively rigid metallic member, such as
a stainless steel shaft, is used for the shaft portion 22. The
shaft 22 is secured to a handle 26 near its proximal end, where a
Luer connector 28 is provided.
[0029] The distal end 24 of the shaft 22 illustrates a number of
attachment features, including a groove 30 and a suture hole 32.
For example, the groove 30 may be a radial groove allowing for
slipknot attachment to a thread such as a suture. The suture hole
32 may allow for a thread or suture to be passed therethrough and
then tied. The end of the tool might also possess specific
geometries for attachment to specific electrode designs.
[0030] Referring to FIG. 2B, the tool 20 is shown in a cut-away or
section view, with the shaft 22 extending through the handle 26.
The shaft 22 defines a lumen 34 that extends from the Luer
connector 28 to an infusion port opening into the suture hole 32.
The handle 26 may be secured to the shaft 22 in any suitable
manner, for example, with adhesives, mechanical securing devices
(i.e., mating threads, notches, or the like), heat welding, or by
overmolding the handle 26 onto the shaft 22. One way to provide
additional mechanical strength to any such attachment is to include
an offset bend 36 in the shaft 22 under the handle 26.
[0031] FIGS. 3A-3B show, in perspective and section views, a curved
electrode insertion tool. The features are generally similar to
those of FIGS. 2A-2B. Referring to FIG. 3A, the tool 40 has a
gradual or smooth curve which may be selected or shaped to match a
patient's anatomy. In particular, in preferred embodiments, the
curve is chosen to correspond to the curvature of a patient's rib,
allowing less traumatic passage through the subcutaneous space of a
patient along the patient's chest.
[0032] The tool 40 includes a shaft portion 42 that is preferably
stiff enough to provide pushability to a distal end 44 for creating
a path through tissue. In several embodiments, a relatively rigid
metallic member, such as a stainless steel shaft, is used for the
shaft portion 42. The shaft 42 is secured to a handle 46 near its
proximal end, where a Luer connector 48 is provided. Instead of a
metallic member, a pushable polymeric member may be used, or,
alternatively, a braided shaft member including polymeric layers
and a braided support structure.
[0033] The distal end 44 of the shaft 42 illustrates a couple of
attachment features, including a groove 50 and a suture hole 52.
For example, the groove 50 may be a radial groove allowing for
slipknot attachment to a thread such as a suture. The suture hole
52 may allow for a thread or suture to be passed therethrough and
then tied. In another embodiment, a staple may pass through the
hole 52 such that, rather than having a person physically tie or
knot a suture, a surgical stapler may be used instead.
[0034] Referring to FIG. 3B, the tool 40 is shown in section or
cut-away view with the shaft 42 extending through the handle 46.
The shaft 42 defines a lumen 54 that extends from the Luer
connector 48 to an infusion port opening into the suture hole 52.
The handle 46 may be secured to shaft 42 in any suitable way, for
example, with adhesives, mechanical securing devices (i.e.,
threads, notches, or the like), heat welding, or by overmolding the
handle 46 onto the shaft 42. One way to improve the mechanical
strength of the bond is to include an offset bend 56 in the shaft
42 under the handle 46.
[0035] FIGS. 4A-4C show detailed section views of an electrode
insertion tool handle. The electrode insertion tool handle 60 may
correspond to the handles 26, 46 illustrated in FIGS. 2A-2B and
3A-3B. The handle 60 includes a Luer port 62 for providing access
to a lumen defined by the shaft 66. As shown in FIG. 4B, the Luer
port/valve 62 includes a proximal securing portion 70 for securing
to, for example, a fluid infusion device, and a distal securing
portion 72 for securing to the shaft 66.
[0036] In an illustrative example, a local anesthetic such as
lidocaine may be infused. Other anesthetics, anti-infection drugs,
or drugs designed/chosen to prevent or limit swelling or other
tissue injury responses may be infused as well. An advantage of
providing a medication limiting tissue injury response may be to
limit the size of any tissue growth around an implanted lead.
Alternatively, for example to ensure good anchoring of a lead, a
substance designed to cause or maximize local tissue injury
response may be provided. Additionally, certain tissue adhesives
could also be delivered through the lumen.
[0037] The main handle portion 64, as seen in FIGS. 4A and 4C may
be designed to have a flattened side and a wider side. This design
aids a doctor/practitioner in grasping the device during tunneling
and pulling with the shaft 66, as well as providing space for the
offset bend 68 shown in FIG. 4A. The offset bend 68 of the shaft 66
aids in anchoring the shaft 66 in the main handle portion 64. Other
handle designs may be used in accordance with the present
invention.
[0038] FIGS. 5A-5B show, in perspective and section views, details
of an electrode insertion tool tip. The tip 80 may correspond to
the distal ends 24, 44 illustrated in FIGS. 2A-2B and 3A-3B. The
tip 80 includes a rounded end 82 which may have a "bullet" shape
for tunneling between tissue layers while avoiding tunneling
through tissue layers. In a preferred embodiment, the rounded end
82 is tapered to allow tunneling into fatty subcutaneous tissue
without perforating the skin. Also included are two illustrative
attachment features, including a suture hole 84 and a radial groove
86 allowing for suture attachment using, for example, a
slipknot.
[0039] The tip 80 with end 82, suture hole 84 and groove 86 is also
shown in FIG. 5B. Also shown in FIG. 5B is a lumen 88 that
terminates in an infusion port that opens laterally through the
suture hole 84. With this structure, the suture hole 84 serves two
functions, both as an attachment feature and as an extension of the
infusion port. The lumen 88 extends through the rest of the shaft
(not shown) to a handle and Luer valve such as those shown in FIGS.
2A-2B and 3A-3B.
[0040] FIGS. 6A-6C show perspective and alternative detail views of
a lead electrode assembly. The lead electrode assembly 90 is shown
as having a number of electrodes, including a coil electrode 92 and
two sense electrodes 94. The assembly 90 has a distal tip 96. As
shown in FIG. 6A and further illustrated in FIG. 6B, the distal tip
96 may include a suture hole 98, although any other attachment
feature may be used, such as a radial groove as shown in FIGS.
5A-5B or a hook/notch 98' as shown in FIG. 6C in association with
tip 96'. For a radial groove 86 or a hook/notch 98', a loop of
suture material (or string, for example) or a staple may be secured
to the distal tip 96, 96' by tightening the loop into the groove 86
or hook/notch 98'. The inclusion of a coil electrode 92 and two
sense electrodes 94 is merely illustrative of one lead electrode
assembly that may be inserted with the aid of the methods/devices
of the present invention.
[0041] FIG. 7 shows a perspective view of an insertion tool bending
device. The bending device 100 includes posts 102 separated by a
gap 104. To bend a device such as the shaft of the insertion tools
20, 40 shown in FIGS. 2A-2B or 3A-3B, the shaft of the chosen
device is passed through the gap 104 and turned with respect to the
bending tool 100, allowing the posts 102 to reshape the device with
a different curve. This may be done to match a chosen insertion
tool more accurately to a patient's anatomy. The posts 102 may be
modified by including caps, notches, grooves, hooks, overhangs or
the like for retaining a device shaft going through the gap 104 to
prevent it from slipping out.
[0042] FIG. 8 shows a perspective partial view of an infusion
tubing set. The tubing set 110 may be used in conjunction with one
of the insertion tools 20, 40 shown in FIGS. 2A-2B or 3A-3B. The
tubing set 110 is used to provide a flexible extension enabling
easy attachment of a fluid infusion device to the Luer valve of a
chosen insertion tool. The tubing set 110 includes first and second
connectors 112, 114 and a flexible tubular shaft 116
therebetween.
[0043] FIGS. 9A-9B show, in combination and alone, an insertion
tool with a splittable sheath and a splittable sheath by itself.
FIG. 9A illustrates an insertion tool 150 having a handle 152 and a
shaft 154 extending to a distal tip 156, with a splittable sheath
158 disposed thereon. The splittable sheath 158 is sized to snugly
fit over the shaft 154, and is preferably shorter than the shaft
154 such that the distal end 156 can extend distally of the
splittable sheath 158.
[0044] As further shown in FIG. 9B, the splittable sheath 158 has a
proximal handle portion 160 and a distal end 162. The distal end
162 may be tapered or thinned such that there is no leading
"shoulder" during insertion to tissue. Preferably, the splittable
sheath 158 is thin enough that the distal end 162 of the splittable
sheath 158 does not create significant drag during insertion, and
does not require thinning, grinding, or the like.
[0045] Alternatively, though not shown in FIG. 9A, the insertion
tool 150 may include a proximally facing lip near its distal end
for seating the distal end of the splittable sheath 152. Such a
proximally facing lip may be provided by preloading the splittable
sheath 152 on the shaft and then providing an overlay or separate
tip that can be secured (i.e., by heating, welding or adhesive) to
the distal end of the shaft. In another embodiment (referring again
to FIG. 9B), the distal end 162 of the splittable sheath 158 may be
ground to smooth out the distal shoulder. The splittable sheath 158
also includes a region of longitudinal weakness 164 for splitting
the handle 160, which also extends toward the distal end 162,
allowing for splitting of the sheath itself.
[0046] FIG. 10 shows a patient illustrating relative positions for
incisions in an example procedure. The patient 200 is shown with
the median plane 202 defined and a rough illustration of the heart
204 provided. Incision locations for a first incision 206 and a
second incision 208 are shown, again as a relatively rough
approximation. Preferably the incisions 206, 208 both lie over the
same rib or between the same pair of ribs of the patient 200. Each
incision is deep enough to enable subcutaneous access, but
preferably does not extend further into patient 200. Such incisions
may be made over any of the patients ribs, but are preferably made
somewhere between the third and twelfth ribs of the patient. In
another preferred embodiment, the line from the first incision to
the second incision tracks, at least partly, the inframammary
crease. The second incision is also preferably made in the region
of the left anterior axillary line. While these are presently
preferred locations, the specific locations of each incision may
vary widely within the context of the present invention.
[0047] FIGS. 11A-11J show an illustrative method of electrode
insertion. FIG. 11A illustrates a first step after the making of a
first incision 206 and a second incision 208 in a patient 200. Note
also that a pocket 207 has been defined in the subcutaneous region
of the patient 200. The pocket 207 may be formed by inserting a
trocar through the second incision and separating tissue layers
with the trocar to define a subcutaneous pocket 207 or by using
manual blunt dissection for receipt of an implantable device. An
insertion tool 210 (illustrated as including a splittable sheath
218 thereon) is about to be inserted through the first opening 206.
As shown in FIG. 11B, the insertion tool 210 is advanced from the
first opening 206 toward and through the second opening, tunneling
a path through the subcutaneous tissue along the way. While
advancement of the distal end 212 through the second incision 208
is shown, this extent of insertion is not necessary. It is
sufficient that the insertion tool 210 is advanced far enough to
provide access from outside of incision 208 to the distal end 212
of the insertion tool 210 for access to an attachment feature. The
attachment feature shown in FIG. 11B is shown, for illustrative
purposes, as including a suture hole 216. During such insertion and
tunneling, a local anaesthetic such as Lidocaine or the like may be
supplied by infusion through a Luer hub 214 and passage through a
lumen in the insertion tool 210.
[0048] As shown in FIG. 11C, a next step includes attaching the
distal end of a lead electrode assembly 220 to the distal end 212
of the insertion tool 210 using a suture loop 224 that passes
through the insertion tool 210 suture hole 216 and a corresponding
suture hole 222 on the lead electrode assembly 220. The
illustrative lead electrode assembly 220 is shown having two
sensing and one shocking electrode thereon; such a configuration is
merely illustrative of one lead assembly, and use of the present
invention need not be limited to such electrode lead
assemblies.
[0049] Instead of suture holes 216, 222, other attachment features
such as hooks or radial grooves, as illustrated above, may be used.
Magnetic, screw-type, locking ball, snap fit, or other types of
attachment may be substituted as well, though for the purposes of
illustration, magnetic, screw-type, locking ball and snap fit
attachment features have not been shown herein. It is sufficient
that the attachment feature enable attachment of the insertion tool
distal end to another element such as a lead electrode assembly.
Advantageously, the suture holes, hooks or radial grooves allow for
relatively simple and reliable attachment using readily available
(and strong) suture material or staples. In particular, attaching a
suture or staple is relatively simple. For sutures, any type of
knot may be used, from simple slipknots to many stronger and more
complex knots, to achieve a strong attachment. Removal is also
simple, easy, and foolproof, being performed by merely cutting the
suture/staple 224.
[0050] Referring now to FIG. 11D, a next step is illustrated
wherein the insertion tool 210 is withdrawn through the first
incision 206, pulling the lead electrode assembly 220 into the path
tunneled by the insertion tool 210 between the incisions 206, 208
using the suture 224 and suture holes 216, 222. As shown, this step
is performed until at least the suture 224 can be accessed from
outside the patient.
[0051] In one embodiment of the present invention, the method may
stop here. With the lead electrode assembly 220 pulled into the
path between the incisions 206, 208, the lead assembly 220 may be
sized such that a canister 230 attached to the proximal end of the
lead electrode assembly 220 is pulled into the pocket 207. The
suture 224 is then cut and the incisions 206, 208 sewn shut, such
that implantation is essentially complete insofar as device
placement is concerned. Because the lead assembly 220 is pulled
into position after tunneling, rather than being carried or pushed
into position, the resultant strains on the lead assembly 220 are
reduced. Further, by advancing from a first incision 206 at a
definite location to a second incision 208 at another definite
location, both ends of the path so defined can be tightly
controlled. Thus, placement inaccuracy is avoided.
[0052] An alternative embodiment continues in FIGS. 11E-11J. After
the step of FIG. 11D, as shown in FIG. 11E, the lead electrode
assembly 220 is pulled for a greater distance allowing access to
the distal end 222 thereof. The lead assembly 220 may be pulled
sufficiently to cause it to exit the first incision 206 by a
certain amount. Then, as shown in FIG. 11F, the insertion tool 210
with the splittable sheath 218 is re-inserted into the first
incision 206, this time in a different direction than before. In an
alternative embodiment, a first, preferably curved, insertion tool
is used during the steps shown in FIGS. 11A-11E while a second,
preferably straight, insertion tool is used in FIGS. 11F-11J, with
the splittable sheath provided only for the straight insertion
tool.
[0053] As shown in FIG. 11G, the insertion tool 210 is inserted via
the first incision 206 toward a chosen point or location X 232
located cephalic (directed toward the head of the patient) of the
first incision. Preferably, a line drawn from the first incision
206 to the second incision 208 is at an angle .theta., between
about 20 and 160 degrees, with respect to a line drawn from the
first incision toward location X 232. More preferably, the angle
.theta. is around about 90 degrees, being in the range of between
75 and 105 degrees.
[0054] After the insertion tool 210 has tunneled a desired
distance, and while the splittable sheath 218 may still be accessed
from outside the patient, the insertion tool 210 is removed to
leave the splittable sheath 218 in place, as shown in FIG. 11H.
Next, the distal end of the lead electrode assembly 220 is directed
into the splittable sheath 218, as also shown in FIG. 11H. Once the
lead assembly 220 is directed into the splittable sheath 218 to a
desired distance, the splittable sheath 218 may be removed by
grasping handles 234 and tearing the sheath apart, as shown in FIG.
11I. At this point, as shown in FIG. 11I, the lead assembly 220 is
preferably far enough into the patient longitudinally that the
canister 230 has entered the pocket 207 and is inside the patient
200, through incision 208. As shown at FIG. 11J, the incisions 206,
208 are then closed, leaving the lead electrode assembly 220 and
canister 230 fully implanted. After this point, the implantation is
complete, and a variety of methods may be used to "activate" and/or
program the canister 230 and whatever electronics for pacing and/or
defibrillation are contained therein.
[0055] An advantage of the configuration for implantation of the
electrode assembly shown in FIG. 11J is that the electrodes on the
lead electrode assembly 220 are aligned in a new manner with
respect to the canister 230. In prior art devices, the canister 230
was often generally collinear with the electrodes on the lead
electrode assembly. An electrode on the canister 230 may be offset
from the axial direction of the lead electrode assembly, allowing
for some minor angular variation in exchange for reducing the
distance between electrodes. Even if there were more than two
sensing electrodes, the signals received by distinct sensing
electrode pairs would have little variation, since collinear
electrodes generally do not receive significantly different signals
in the far-field, except for pairs that are close together and
therefore yield poor signal anyway. The assembly inserted as shown
in FIG. 11J enables multiple sensors on the distal end of the lead
assembly 220, along with at least one canister electrode, to
provide a wider variation in angular orientation, without closing
the distance between the canister and the electrodes.
[0056] FIGS. 12A-12B help to further illustrate several relevant
sensor characteristics. It should be recognized that, at least with
far-field sensing of electrical activity in the heart, parallel
sensor pairs tend to receive highly correlated signals. Over a
short distance, there is little to be gained by having more than
two sensors along the same line. Given a sensing lead electrode
assembly and canister device as shown and oriented in FIG. 12A,
dead signal sensing problems can arise.
[0057] Given sensor X on a canister 300, and sensors Y and Z on the
lead electrode assembly 302, the primary difficulty arises when the
need for backup sensing is greatest. In particular, if a minimal
signal is sensed between a first sensor pair XY, a similarly
minimal signal will be received by sensor pair YZ as well as signal
pair XZ, since the three electrodes are collinear. If the minimal
received signal is too close to the noise floor, then the sensors
will fail to provide adequate data for reliable QRS detection, let
alone sufficient information to provide pacing or defibrillating
assistance. Even if X is offset from the line of the lead electrode
assembly 302, the angular distinctions between pairs XY, XZ and YZ
are quite small.
[0058] As shown in FIG. 12B, three sensors X, Y, and Z on a lead
assembly 312 coupled to a canister 310 define three sensor pair
vectors 314, 316, and 318 which have angles .alpha., .beta., and
.gamma. therebetween. The above problem is avoided when the
electrodes X, Y, and Z are not generally collinear, as shown.
Angles .alpha., .beta. and .gamma. are all relatively large, each
being bigger than about fifteen degrees. If orthogonal sensing
pairs are used, when the minimum signal is received by one of the
pairs, a maximum signal is received by the other pair. While the
vectors of XY, XZ and YZ are not exactly orthogonal, their
deviation from being collinear is sufficient to eliminate the
problems that arise with the configuration of FIG. 12A. When sensor
backup is most needed (minimum signal received by one pair), the
configuration or layout of FIG. 12B provides excellent backup.
[0059] In another embodiment (relying on another form of analysis),
the insertion method is performed so that three sensors define a
plane which at least partly intersects the heart. In yet another
embodiment, sensors are placed so that at least one angle between
sensor pair vectors is greater than 30 degrees. More preferably, at
least one angle between sensor pair vectors is greater than about
60 degrees, while most preferably at least one angle between sensor
pair vectors is in the range of about 70-90 degrees. Note that when
referring to angles between sensor pair vectors, the angles
referred to are the lesser angles between pairs of intersecting
vectors. Another preferred layout is one in which the sine of the
angles between sensing vectors is intentionally increased,
preferably so that the sine of at least one such angle between
sensing vectors is greater than or equal to about 0.5.
[0060] The layout of FIG. 12B illustrates only three sensors for
the purpose of simplicity. It may be preferable to include four
electrodes, with one canister electrode being both a sensing and a
shocking electrode, while two lead electrodes are only sensing
electrodes provided distal of and proximal of a shocking/sensing
electrode coil. Indeed, unless specifically limited by the use of
non-inclusive language in the following claims, the number of
sensors used in a lead electrode assembly should not be understood
as limiting the present invention.
[0061] Those skilled in the art will recognize that the present
invention may be manifested in a variety of forms other than the
specific embodiments described and contemplated herein.
Accordingly, departures in form and detail may be made without
departing from the scope and spirit of the present invention as
described in the appended claims.
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