U.S. patent application number 12/752914 was filed with the patent office on 2010-10-07 for delivery wire for occlusive device delivery system.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to Hancun Chen, Jimmy Dao, Richard Murphy.
Application Number | 20100256666 12/752914 |
Document ID | / |
Family ID | 42136232 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100256666 |
Kind Code |
A1 |
Chen; Hancun ; et
al. |
October 7, 2010 |
DELIVERY WIRE FOR OCCLUSIVE DEVICE DELIVERY SYSTEM
Abstract
A delivery wire assembly for delivery of an occlusive device to
a location in a patient's vasculature includes a delivery wire
conduit having a proximal tubular portion connected to a distal
coil portion, and a conduit lumen extending through the proximal
tubular portion and the distal coil portion. The delivery wire
assembly also includes a core wire disposed in the conduit lumen
and having a distal end coupled to an occlusive device. The distal
coil portion of the delivery wire assembly includes a plurality of
zones and the plurality of zones decrease in stiffness distally
along the length of the distal coil portion of the delivery wire
assembly.
Inventors: |
Chen; Hancun; (Fremont,
CA) ; Dao; Jimmy; (San Jose, CA) ; Murphy;
Richard; (Sunnyvale, CA) |
Correspondence
Address: |
VISTA IP LAW GROUP LLP
12930 Saratoga Avenue, Suite D-2
Saratoga
CA
95070
US
|
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
42136232 |
Appl. No.: |
12/752914 |
Filed: |
April 1, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61166888 |
Apr 6, 2009 |
|
|
|
Current U.S.
Class: |
606/191 |
Current CPC
Class: |
A61B 2017/12068
20130101; A61B 17/1215 20130101; A61B 2017/12063 20130101; A61B
17/12145 20130101; A61B 17/1214 20130101; A61B 17/12109 20130101;
A61M 2025/09133 20130101; A61B 17/12113 20130101; A61M 2025/0915
20130101; A61B 90/39 20160201; A61B 17/12022 20130101 |
Class at
Publication: |
606/191 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1. A delivery wire assembly for delivery of an occlusive device to
a location in a patient's vasculature, comprising: a delivery wire
conduit having a proximal tubular portion connected to a distal
coil portion, and a conduit lumen extending through the proximal
tubular portion and the distal coil portion; and a core wire
disposed in the conduit lumen and having a distal end coupled to
the occlusive device, wherein the distal coil portion of the
delivery wire assembly comprises a plurality of coils formed from
coil wire which decrease in stiffness distally along the length of
the distal coil portion of the delivery wire assembly.
2. The delivery wire assembly of claim 1, wherein a stiffness of a
distal-most coil of the plurality is 80-85% of a stiffness of a
proximal-most coil of the plurality.
3. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone, middle zone, and distal zone, and
wherein a stiffness of the middle zone coils is 86-95% of a
stiffness of the proximal zone coils, and a stiffness of the distal
zone coils is 80-85% of a stiffness of the proximal zone coils.
4. The delivery wire assembly of claim 3, wherein coils of a
proximal-most zone of the plurality have a less open pitch than
coils of a distal-most zone of the plurality.
5. The delivery wire assembly of claim 4, wherein the coils of the
distal-most zone have a pitch in the range of 10-20%.
6. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone, middle zone, and distal zone, and
wherein coils of the proximal zone have a less open pitch than do
coils of the middle zone, and coils of the middle zone have a less
open pitch than do coils of the distal zone.
7. The delivery wire assembly of claim 6, wherein the coils of the
proximal zone have a pitch of about 0%, the coils of the middle
zone have a pitch in the range of 5-9%, and the coils of the distal
zone have a pitch in the range of 10-20%.
8. The delivery wire assembly of claim 7, wherein the coils of the
proximal zone have a pitch of about 0%, the coils of the middle
zone have a pitch of about 5%, and the coils of the distal zone
have a pitch of about 10%.
9. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone and distal zone, and wherein a coil wire
of the proximal zone has a larger outer diameter than a coil wire
of the distal zone.
10. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone, middle zone, and distal zone, and
wherein a coil wire of the proximal zone has a larger outer
diameter than a coil wire of the middle zone, and a coil wire of
the middle zone has a larger outer diameter than a coil wire of the
distal zone.
11. The delivery wire assembly of claim 10, wherein the coil wire
of the proximal zone has an outer diameter of about 0.00250 inches,
the coil wire of the middle zone has an outer diameter of about
0.00225 inches, and the coil wire of the distal zone has an outer
diameter of about 0.00200 inches.
12. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone and distal zone, and wherein a coil wire
of the proximal zone has a higher tensile strength than a coil wire
of the distal zone.
13. The delivery wire assembly of claim 1, wherein the coils of the
distal coil portion of the delivery wire assembly form a respective
proximal zone, middle zone, and distal zone, and wherein a coil
wire of the proximal zone has a higher tensile strength than the
coil wire of the middle zone, and a coil wire of the middle zone
has a higher tensile strength than the coil wire of the distal
zone.
14. The delivery wire assembly of claim 13, wherein the coil wire
of the proximal zone has an ultimate tensile strength in the range
of 300-350 ksi, the coil wire of the middle zone has an ultimate
tensile strength in the range of 250-299 ksi, and the coil wire of
the distal zone has an ultimate tensile strength in the range of
200-249 ksi.
15. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone and distal zone, and wherein a coil wire
of the proximal zone has a higher modulus of elasticity than a coil
wire of the distal zone.
16. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone, middle zone, and distal zone, and
wherein a coil wire of the proximal zone has a higher modulus of
elasticity than a coil wire of the middle zone, and a coil wire of
the middle zone has a higher modulus of elasticity than a coil wire
of the distal zone.
17. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone and distal zone, and wherein a coil wire
of the proximal zone has a circular cross section and a coil wire
of the distal zone has an ellipsoid cross section.
18. The delivery wire assembly of claim 1, wherein the plurality of
coils in the distal coil portion of the delivery wire assembly form
a respective proximal zone, middle zone, and distal zone, a coil
wire of the proximal zone having a circular cross section, a coil
wire of the middle zone having an ellipsoid cross section, and a
coil wire of the distal zone having an ellipsoid cross section with
a larger major axis than the ellipsoid cross section of the coil
wire of the middle zone.
19. The delivery wire assembly of claim 1, wherein the distal coil
portion of the delivery wire assembly comprises a laminated coil
wire, with the lamination covering a proximal-most zone of coils
being thicker than the lamination covering a distal-most zone of
coils.
20. An occlusive device delivery system, comprising: a delivery
catheter comprising a proximal end, a distal end, and a catheter
lumen extending between the proximal and distal ends; a delivery
wire assembly, comprising: a delivery wire conduit having a
proximal tubular portion connected to a distal coil portion, and a
conduit lumen extending through the proximal tubular portion and
the distal coil portion; and a core wire disposed in the conduit
lumen and having a distal end coupled to an occlusive device,
wherein the distal coil portion of the delivery wire assembly
comprises a plurality of zones and the plurality of zones comprise
coils formed from coil wire and decrease in stiffness distally
along the length of the distal coil portion of the delivery wire
assembly; and a power supply electrically connected to the core
wire.
Description
RELATED APPLICATION DATA
[0001] The present application claims the benefit under 35 U.S.C.
.sctn.119 to U.S. Provisional application Ser. No. 61/166,888 filed
Apr. 6, 2009. The foregoing application is hereby incorporated by
reference into the present application in its entirety.
FIELD OF THE INVENTION
[0002] The field of the invention generally relates to systems and
delivery devices for implanting vaso-occlusive devices for
establishing an embolus or vascular occlusion in a vessel of a
human or veterinary patient.
BACKGROUND OF THE INVENTION
[0003] Vaso-occlusive devices or implants are used for a wide
variety of reasons, including treatment of intra-vascular
aneurysms. Commonly used vaso-occlusive devices include soft,
helically wound coils formed by winding a platinum (or platinum
alloy) wire strand about a "primary" mandrel. The relative
stiffness of the coil will depend, among other things, on its
composition, the diameter of the wire strand, the diameter of the
primary mandrel, and the pitch of the resulting primary windings.
The coil is then wrapped around a larger, "secondary" mandrel, and
heat treated to impart a secondary shape. For example, U.S. Pat.
No. 4,994,069, issued to Ritchart et al., describes a
vaso-occlusive coil that assumes a linear, helical primary shape
when stretched for placement through the lumen of a delivery
catheter, and a folded, convoluted secondary shape when released
from the delivery catheter and deposited in the vasculature.
[0004] In order to deliver the vaso-occlusive coils to a desired
site in the vasculature, e.g., within an aneurismal sac, it is
well-known to first position a small profile, delivery catheter or
"micro-catheter" at the site using a steerable guidewire.
Typically, the distal end of the micro-catheter is provided, either
by the attending physician or by the manufacturer, with a selected
pre-shaped bend, e.g., 45.degree., 90.degree., "J", "S", or other
bending shape, depending on the particular anatomy of the patient,
so that it will stay in a desired position for releasing one or
more vaso-occlusive coil(s) into the aneurysm once the guidewire is
withdrawn. A delivery or "pusher" wire is then passed through the
micro-catheter, until a vaso-occlusive coil coupled to a distal end
of the delivery wire is extended out of the distal end opening of
the micro-catheter and into the aneurysm. The vaso-occlusive device
is then released or "detached" from the end delivery wire, and the
delivery wire is withdrawn back through the catheter. Depending on
the particular needs of the patient, one or more additional
occlusive devices may be pushed through the catheter and released
at the same site.
[0005] One well-known way to release a vaso-occlusive coil from the
end of the pusher wire is through the use of an electrolytically
severable junction, which is a small exposed section or detachment
zone located along a distal end portion of the pusher wire. The
detachment zone is typically made of stainless steel and is located
just proximal of the vaso-occlusive device. An electrolytically
severable junction is susceptible to electrolysis and disintegrates
when the pusher wire is electrically charged in the presence of an
ionic solution, such as blood or other bodily fluids. Once the
detachment zone exits out of the catheter distal end and is exposed
in the vessel blood pool of the patient, a current applied through
an electrical contact to the conductive pusher wire completes a
circuit with a return electrode, and the detachment zone
disintegrates due to electrolysis. Return electrodes include
electrodes attached to the patient's skin, conductive needles
inserted through the skin at a remote site, and electrodes located
on the pusher wire but electrically insulated from the conductive
path ending in the detachment zone.
[0006] One perceived problem with current vaso-occlusive coil
delivery systems is that the detachment zone of the pusher wire
bends as the vaso-occlusive coil is pushed through the
micro-catheter. Orthogonal forces generated as a stiff pusher wire
takes on the shapes of various bends in the micro-catheter may be
sufficient to bend the detachment zone. This bending may adversely
impact the placement of the embolic coil within the aneurysm and
detachment of the embolic coil by electrolysis.
[0007] Another perceived problem is that pusher wires tend to have
a stiff distal section that complicates accurate placement of the
delivery system at the desired location, i.e., a stiff distal
section of the pusher wire can cause a pre-shaped micro-catheter to
kick back or recoil from the aneurysm upon coil deployment and
release.
SUMMARY
[0008] In accordance with various embodiments, a delivery wire
assembly for delivery of occlusive devices to locations in a
patient's vasculature includes a delivery wire conduit having a
proximal tubular portion connected to a distal coil portion, and a
conduit lumen extending through the proximal tubular portion and
the distal coil portion. The delivery wire assembly also includes a
core wire disposed in the conduit lumen and having a distal end
coupled to an occlusive device. The distal coil portion of the
delivery wire assembly includes a plurality of coils formed from
coil wire, including one or more respective proximal, middle and
distal coils, which decrease in stiffness distally along the length
of the distal coil portion of the delivery wire assembly. The
stiffness of the middle coil may be, by way of non-limiting
example, 86-95% of the stiffness of the proximal coil, and the
stiffness of the distal coil (again, by way of non-limiting
example) may be 80-85% of the stiffness of the proximal coil.
[0009] In some embodiments, the most proximal coil(s) may have a
pitch of about 0%, the middle coil(s) have a pitch in the range of
5-9%, and the most distal coil(s) have a pitch in the range of
10-20%. In some embodiments, the coil wire of the proximal coil(s)
has an outer diameter of about 0.00250 inches, the coil wire of the
middle coil(s) has an outer diameter of about 0.00225 inches, and
the coil wire of the most distal coil(s) has an outer diameter of
about 0.00200 inches. In some embodiments, the coil wire of the
proximal coil(s) has an ultimate tensile strength in the range of
300-350 ksi, the coil wire of the middle coil(s) has an ultimate
tensile strength in the range of 250-299 ksi, and the coil wire of
the most distal coil(s) has an ultimate tensile strength in the
range of 200-249 ksi. In some embodiments, the coil wire of the
proximal coil(s) has a higher modulus of elasticity than the coil
wire of the middle coil(s), and the coil wire of the middle coil(s)
has a higher modulus of elasticity than the coil wire of the distal
coil(s). In some embodiments, the coil wire of the proximal coil(s)
has a circular cross section, the coil wire of the middle coil(s)
has an ellipsoid cross section, and the coil wire of the distal
coil(s) has an ellipsoid cross section with a larger major axis
than the ellipsoid cross section of the coil wire of the middle
coil(s). In some embodiments, the coil wire is laminated, wherein
the lamination covering the coil wire of the proximal coil(s) is
thicker than the lamination covering the coil wire of the middle
zone, and the lamination covering the coil wire of the middle
coil(s) is thicker than the lamination covering the coil wire of
the distal coil(s).
[0010] In another alternative embodiment, an occlusive device
delivery system includes a delivery catheter having a proximal end,
a distal end, and a catheter lumen extending between the proximal
and distal ends. The occlusive device delivery system according to
this further alternative embodiment also includes a delivery wire
assembly having a delivery wire conduit having a proximal tubular
portion connected to a distal coil portion, and a conduit lumen
extending through the proximal tubular portion and the distal coil
portion, and a core wire disposed in the conduit lumen and having a
distal end coupled to an occlusive device via an electrolytically
severable junction. The distal coil portion of the delivery wire
assembly includes a plurality of coils that decrease in stiffness
distally along the length of the distal coil portion of the
delivery wire assembly. The occlusive device delivery system also
includes a power supply electrically connected to the core
wire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Referring now to the drawings in which like reference
numbers represent corresponding parts throughout, and in which:
[0012] FIG. 1 illustrates an occlusive coil delivery system,
according to one embodiment.
[0013] FIG. 2 is a longitudinal cross-sectional view of a delivery
wire assembly, according to one embodiment.
[0014] FIG. 3A to 3F are detailed longitudinal cross-sectional
views of delivery wire assemblies, according to various
embodiments.
[0015] FIG. 4 illustrates an occlusive coil in a natural state
mode, illustrating one exemplary secondary configuration.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0016] FIG. 1 illustrates an occlusive coil delivery system 10
according to one embodiment. The system 10 includes a number of
subcomponents or sub-systems. These include a delivery catheter
100, a delivery wire assembly 200, an occlusive coil 300, and a
power supply 400. The delivery catheter 100 includes a proximal end
102, a distal end 104, and a lumen 106 extending between the
proximal and distal ends 102, 104. The lumen 106 of the delivery
catheter 100 is sized to accommodate axial movement of the delivery
wire assembly 200. Further, the lumen 106 is sized for the passage
of a guidewire (not shown) which may optionally be used to properly
guide the delivery catheter 100 to the appropriate delivery
site.
[0017] The delivery catheter 100 may include a braided-shaft
construction of stainless steel flat wire that is encapsulated or
surrounded by a polymer coating. For example, HYDROLENE.RTM. is one
exemplary polymer coating that may be used to cover the exterior
portion of the delivery catheter 100. Of course, the system 10 is
not limited to a particular construction or type of delivery
catheter 100 and other constructions known to those skilled in the
art may be used for the delivery catheter 100.
[0018] The inner lumen 106 is advantageously coated with a
lubricious coating such as PTFE to reduce frictional forces between
the delivery catheter 100 and the device that is being moved
axially within the lumen 106. The delivery catheter 100 may include
one or more optional marker bands 108 formed from a radiopaque
material that can be used to identify the location of the delivery
catheter 100 within the patient's vasculature system using imaging
technology (e.g., fluoroscope imaging). The length of the delivery
catheter 100 may vary depending on the particular application but
generally is around 150 cm in length. Of course, other lengths of
the delivery catheter 100 may be used with the system 10 described
herein.
[0019] The delivery catheter 100 may include a distal end 104 that
is straight as illustrated in FIG. 1. Alternatively, the distal end
104 may be pre-shaped into a specific geometry or orientation. For
example, the distal end 104 may be shaped into a "C" shape, an "S"
shape, a "J" shape, a 45.degree. bend, a 90.degree. bend. The size
of the lumen 106 may vary depending on the size of the delivery
wire assembly 200 and occlusive coil 300 but generally the diameter
lumen 106 of the delivery catheter 100 (I.D. of delivery catheter
100) is less than about 0.02 inches. The delivery catheter 100 is
known to those skilled in the art as a microcatheter. While not
illustrated in FIG. 1, the delivery catheter 100 may be utilized
with a separate guide catheter (not shown) that aids in guiding the
delivery catheter 100 to the appropriate location within the
patient's vasculature.
[0020] Still referring to FIG. 1, the system 10 includes a delivery
wire assembly 200 that is configured for axial movement within the
lumen 106 of the delivery catheter 100. The delivery wire assembly
200 generally includes a proximal end 202 and a distal end 204. The
delivery wire assembly 200 includes a delivery wire conduit 213,
which has a proximal tubular portion 206 and a distal coil portion
208. The proximal tubular portion 206 may be formed from, for
example, stainless steel hypotube. The distal coil portion 208 may
be formed from, for example, stainless steel wire. The distal coil
portion 208 may be bonded to the proximal tubular portion 206 in an
end-to-end arrangement.
[0021] The delivery wire assembly 200 further includes a core wire
210 that extends from the proximal end 202 of the delivery wire
assembly 200 to a location that is distal with respect to the
distal end 204 of the delivery wire assembly 200. The core wire 210
is disposed within a lumen 212 that extends within an interior
portion of the delivery wire conduit 213. The core wire 210 is
formed from an electrically conductive material such as stainless
steel wire. The proximal end 214 of the core wire 210 (shown in
phantom) is electrically coupled to an electrical contact 216
located at the proximal end 202 of the delivery wire assembly 200.
The electrical contact 216 may be formed from a metallic solder
(e.g., gold) that is configured to interface with a corresponding
electrical contact (not shown) in the power supply 400.
[0022] A portion of the core wire 210 is advantageously coated with
an insulative coating 218. The insulative coating 218 may include
polyimide. The entire length of the core wire 210 is coated with an
insulative coating 218 except for the proximal end 214 of the core
wire 210 that is in contact with electrical contact 216 and a small
region 220 located in a portion of the core wire 210 that extends
distally with respect to the distal end 204 of the of the delivery
wire assembly 200. This latter "bare" portion of the core wire 210
forms the electrolytic detachment zone 220 which dissolves upon
application of electrical current from the power supply 400.
[0023] In an alternative embodiment, instead of an electrolytic
detachment zone 220, the sacrificial region may be configured to
break or dissolve in response to thermal energy. For example, the
detachment zone 220 may be formed from a polymeric link (e.g.,
fiber(s)) that melts or dissolves in response to externally applied
thermal energy or heat. The polymeric link may be formed from a
thermoplastic material (e.g., polyethylene) that has a high tensile
strength and appropriate melting temperature. The thermally
responsive sacrificial region may be responsive to an electrical
resistance heater coil that is configured to apply heat to the
detachment zone 220. Such heater coils operate by generating heat
in response to an applied electrical current. Alternatively,
electromagnetic or RF energy may be used to break or dissolve the
sacrificial region. U.S. Pat. No. 7,198,613, which is incorporated
herein by reference, discloses additional details regarding various
thermally-actuated detachment modalities.
[0024] Still referring to FIG. 1, the occlusive coil 300 includes a
proximal end 302, a distal end 304 and a lumen 306 extending there
between. The occlusive coil 300 is generally made from a
biocompatible metal such as platinum or a platinum alloy (e.g.,
platinum-tungsten alloy). The occlusive coil 300 generally includes
a straight configuration (as illustrated in FIG. 1) when the
occlusive coil 300 is loaded within the delivery catheter 100. Upon
release, the occlusive coil 300 generally takes a secondary shape
which may include two-dimensional or three-dimensional
configurations such as that illustrated in FIG. 4. Of course, the
system 10 described herein may be used with occlusive coils 300
having a variety of configurations and is not limited to particular
occlusive coils 300 having a certain size or configuration.
[0025] The occlusive coil 300 includes a plurality of coil windings
308. The coil windings 308 are generally helical about a central
axis disposed along the lumen 306 of the occlusive coil 300. The
occlusive coil 300 may have a closed pitch configuration as
illustrated in FIG. 1.
[0026] The distal end 222 of the core wire 210 is connected to the
proximal end 302 of the occlusive coil 300 at a junction 250.
Various techniques and devices can be used to connect the core wire
210 to the occlusive coil 300, including laser melting, and laser
tack, spot, and continuous welding. It is preferable to apply an
adhesive 240 to cover the junction 250 formed between the distal
end 222 of the core wire 210 and the proximal end 302 of the
occlusion coil 300. The adhesive 240 may include an epoxy material
which is cured or hardened through the application of heat or UV
radiation. For example, the adhesive 240 may include a thermally
cured, two-part epoxy such as EPO-TEK.RTM. 353ND-4 available from
Epoxy Technology, Inc., 14 Fortune Drive, Billerica, Mass. The
adhesive 240 encapsulates the junction 250 and increases its
mechanical stability.
[0027] Still referring to FIG. 1, the system 10 includes a power
supply 400 for supplying direct current to the core wire 210 which
contains the electrolytic detachment zone 220. In the presence of
an electrically conductive fluid (which may include a physiological
fluid such as blood or a flushing solution such as saline), when
the power supply 400 is activated, electrical current flows in a
circuit including the electrical contact 216, the core wire 210,
the electrolytic detachment zone 220, and a return electrode (not
shown). After several seconds (generally less than about 10
seconds), the sacrificial electrolytic detachment zone 220
dissolves and the occlusive coil 300 separates form the core wire
210.
[0028] The power supply 400 will include an onboard energy source
such as batteries (e.g., a pair of AAA batteries) along with drive
circuitry 402. The drive circuitry 402 may include one or more
microcontrollers or processors configured to output a driving
current. The power supply 400 illustrated in FIG. 1 includes a
receptacle 404 that is configured to receive and mate with the
proximal end 202 of the delivery wire assembly 200. Upon insertion
of the proximal end 202 into the receptacle 404, the electrical
contact 216 disposed on the delivery wire assembly 200 electrically
couple with corresponding contacts (not shown) located in the power
supply 400.
[0029] A visual indicator 406 (e.g., LED light) may indicate when
the proximal end 202 of delivery wire assembly 200 has been
properly inserted into the power supply 400. Another visual
indicator 407 may activate if the batteries need to be replaced.
The power supply 400 typically includes an activation trigger or
button 408 that is depressed by the user to apply the electrical
current to the sacrificial electrolytic detachment zone 220.
Typically, once the activation trigger 408 has been activated, the
driver circuitry 402 automatically supplies current until
detachment occurs. The drive circuitry 402 typically operates by
applying a substantially constant current (e.g., around 1.5
mA).
[0030] The power supply 400 may include optional detection
circuitry 410 that is configured to detect when the occlusive coil
300 has detached from the core wire 210. The detection circuitry
410 may identify detachment based upon a measured impedance value.
A visual indicator 412 may indicate when the power supply 400 is
being supplied to the current to the sacrificial electrolytic
detachment zone 220. Another visual indicator 414 may indicate when
the occlusive coil 300 has detached from the core wire 210. As an
alternative to the visual indicator 414, an audible signal (e.g.,
beep) or even tactile signal (e.g., vibration or buzzer) may be
triggered upon detachment. The detection circuitry 410 may be
configured to disable the drive circuitry 402 upon sensing
detachment of the occlusive coil 300.
[0031] The power supply 400 may also contain another visual
indicator 416 that indicates to the operator when non-bipolar
delivery wire assembly is inserted into the power supply 400. As
explained in the background above, non-bipolar delivery wire
assemblies use a separate return electrode that typically is in the
form of a needle that was inserted into the groin area of the
patient. The power supply 400 is configured to detect when a
non-bipolar delivery wire assembly has been inserted. Under such
situations, the visual indicator 416 (e.g., LED) is turned on and
the user is advised to insert the separate return electrode (not
shown in FIG. 1) into a port 418 located on the power supply
400.
[0032] FIG. 2 illustrates a cross-sectional view of the delivery
wire assembly 200 according to one embodiment. Similar elements of
this embodiment are identified with the same reference numbers as
discussed above with respect to FIG. 1. The delivery wire assembly
200 includes a proximal end 202 and a distal end 204 and measures
between around 184 cm to around 186 cm in length. The delivery wire
assembly 200 includes a delivery wire conduit 213 with a proximal
tubular portion 206 and a distal coil portion 208. The proximal
tubular portion 206 may be formed from stainless steel hypotube
having an outer diameter (OD) of 0.01325 inches and inner diameter
(ID) of 0.0075 inches. The length of the hypotube section may be
between around 140 cm to around 150 cm, although other lengths may
also be used.
[0033] As seen in FIG. 2, a distal coil portion 208 is bonded in
end-to-end fashion to the distal face of the proximal tubular
portion 206. The bonding may be accomplished using a weld or other
bond. The distal coil portion 208 may have a length of around 39 cm
to around 41 cm in length. The distal coil portion 208 may comprise
a coil of 0.0025 inches.times.0.006 inches. The first dimension
generally refers to the OD of the coil wire that forms the coil.
The latter dimension generally refers to the internal mandrel used
to wind the coil wire around to form the plurality of coil winds
and is the nominal ID of the coil.
[0034] The distal coil portion 206 is divided into three coil
"zones", a proximal zone 224, a middle zone 226, and a distal zone
228, each zone made of one or more coils, wherein the coils of each
zone differ from each other, including proximal coils 234, middle
coils 236, and distal coils 238. The three types of coils are, in
turn, made up of three types of coil wire, proximal coil wire 244,
middle coil wire 246, and distal coil wire 248. These zones
decrease in stiffness distally along the length of the distal coil
portion 206 of the delivery wire assembly 200. In other words, the
proximal zone 224 is stiffer than the middle zone 226, and the
middle zone 226 is stiffer than the distal zone 228. In one
embodiment, the stiffness of the middle zone is about 86-95% of the
stiffness of the proximal zone, and the stiffness of the distal
zone is about 80-85% of the stiffness of the proximal zone. This
gradual decrease in stiffness along the length of the distal coil
portion 206 minimizes bending, by releasing stress, and maximizes
pushability and trackability. This smooth stiffness transition also
reduces kick back on the delivery catheter 100 during deployment
and detachment of the occlusive coil 300.
[0035] In order to achieve the decrease in stiffness, various
embodiments of the invention include coils and/or coil wires that
vary between zones. In one embodiment, as shown in FIG. 3A, the
pitch of the coils increases distally. Proximal coils 234 have a
pitch of about 0%, middle coils 236 have a pitch in the range of
5-9%, and distal coils 238 have a pitch in the range of 10-20%.
[0036] In another embodiment, as shown in FIG. 3B, the OD of the
coil wire decreases distally. Proximal coil wire 244 has an OD of
about 0.00250 inches, middle coil wire 246 has an OD of about
0.00225 inches, and distal coil wire 248 has an OD of about 0.00200
inches.
[0037] In yet another embodiment, as shown in FIG. 3C, the tensile
strength of the coil wire decreases distally. Proximal coil wire
244 has tensile strength of about 300-350 ksi, middle coil wire 246
has tensile strength of about 250-299 ksi, and distal coil wire 248
has tensile strength of about 200-249 ksi.
[0038] In still another embodiment, as shown in FIG. 3D, the
modulus of elasticity of the coil wire decreases distally. Proximal
coil wire 244 has a higher modulus of elasticity than that of
middle coil wire 246, which has a higher modulus of elasticity than
that of distal coil wire 248.
[0039] In another embodiment, as shown in FIG. 3E, the cross
section of the coil wire changes from circular to more ellipsoid.
Proximal coil wire 244 has a circular cross section, middle coil
wire 246 has an ellipsoid cross section, and distal coil wire 248
has an even more ellipsoid cross section, i.e., an ellipse having a
larger major axis.
[0040] In yet another embodiment, as shown in FIG. 3F, coil wire is
laminated and the lamination becomes thinner distally. Proximal
coil wire lamination 254 is thicker than middle coil lamination
256, which is, in turn, thicker than distal coil lamination
258.
[0041] Although three zones are described for this embodiment, this
invention is not limited to delivery wire assemblies with distal
coil portions having three zones. In alternative embodiments, the
changes in the distal coil portion are continuous, instead of
discrete.
[0042] Referring to FIG. 2, one or more marker coils 205 of the
distal coil portion 208 may be formed from a radiopaque material
(illustrated as solid marker coils 205 in distal coil portion 208).
For example, the distal coil portion 208 may include a segment of
stainless steel coil (e.g., 3 cm in length), followed by a segment
of platinum coil (which is radiopaque and also 3 mm in length),
followed by a segment of stainless steel coil (e.g., 37 cm in
length), and so on and so forth.
[0043] The core wire 210 terminates at electrical contact 216 at
one end and extends distally with respect to the distal coil
portion 208 of the delivery wire conduit 213. The core wire 210 is
coated with an insulative coating 218 such as polyimide except at
the electrolytic detachment zone 220 and the proximal segment
coupled to the electrical contact 216. The electrolytic detachment
zone 220 is located several millimeters (e.g., about 0.02 mm to
about 0.2 mm) distally with respect to the distal end of the distal
coil portion 208. The core wire 210 may have an OD of around 0.0175
inches. A centering coil 260 is affixed to the core wire 210 at a
location within the distal coil portion 208. The centering coil 260
ensures that the core wire 210 is properly oriented within the
delivery wire assembly 200. The centering coil 260 may be bonded
directly to the core wire 210 using an adhesive 240 such as that
described herein. To this end, an adhesive 240 is applied to secure
the core wire 210 and centering coil 260 to the distal coil portion
208. The adhesive 240 may include EPO-TEK.RTM. 353ND-4 described in
more detail above.
[0044] Still referring to FIG. 2, an outer sleeve 262 or jacket
surrounds a portion of the proximal tubular portion 206 and a
portion of the distal coil portion 208 of the delivery wire conduit
213. The outer sleeve 262 covers the interface or joint formed
between the proximal tubular portion 206 and the distal coil
portion 208. The outer sleeve 262 may have a length of around 50 cm
to around 54 cm. The outer sleeve 262 may be formed from a
polyether block amide plastic material (e.g., PEBAX 7233
lamination). The outer sleeve 262 may include a lamination of PEBAX
and HYDROLENE.RTM.. The OD of the outer sleeve 262 may be less than
0.02 inches and advantageously less than 0.015 inches.
[0045] FIG. 4 illustrates one exemplary configuration of an
occlusive coil 300 in a natural state. In the natural state, the
occlusive coil 300 transforms from the straight configuration
illustrated in, for instance, FIG. 1 into a secondary shape. The
secondary shaped may include both two and three dimensional shapes
of a wide variety. FIG. 4 is just one example of a secondary shape
of an occlusive coil 300 and other shapes and configurations are
contemplated to fall within the scope of the invention. Also, the
occlusive coil 300 may incorporate synthetic fibers over all or a
portion of the occlusive coil 300 as is known in the art. These
fibers may be attached directly to coil windings 308 or the fibers
may be integrated into the occlusive coil 300 using a weave or
braided configuration.
[0046] The electrical contact 216 may be manufactured by inserting
a core wire 210 into the lumen 212 of the delivery wire conduit
213. Then a metallic solder can be applied to the proximal end 202
of the delivery wire assembly 200, forming the electrical contact
216. After the metallic solder is allowed to cure, clippers or the
like may be used to trim the excess material. While various
embodiments of the present invention have been shown and described,
they are presented for purposes of illustration, and not
limitation. Various modifications may be made to the illustrated
and described embodiments without departing from the scope of the
present invention, which is to be limited and defined only by the
following claims and their equivalents.
* * * * *