U.S. patent application number 15/150471 was filed with the patent office on 2016-11-17 for device to aid the delivery of a coil of filament.
This patent application is currently assigned to COOK MEDICAL TECHNOLOGIES LLC. The applicant listed for this patent is COOK MEDICAL TECHNOLOGIES LLC. Invention is credited to Aidan P. Furey, Palle Munk Hansen.
Application Number | 20160331379 15/150471 |
Document ID | / |
Family ID | 53489423 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160331379 |
Kind Code |
A1 |
Furey; Aidan P. ; et
al. |
November 17, 2016 |
DEVICE TO AID THE DELIVERY OF A COIL OF FILAMENT
Abstract
A medical filler delivery assembly includes a micro catheter for
delivering filler material such as filamentary material into an
aneurysm in a vessel. The assembly also includes a positioning
mechanism which includes a support element made of knitted wires,
as well as an expansion mechanism for expanding the support element
within the vessel. The support element is able to trap the micro
catheter in position and in practice such that its distal end is
disposed within the aneurysm sac. The knitted wire configuration of
the support element provides sufficient holding force to the distal
end of the micro catheter and also has an open structure which
permits continuation of fluid flow through the vessel. The entire
assembly can be removed from the vessel after the delivery of
filamentary material, thereby not retaining within the vessel any
foreign object such as a stent.
Inventors: |
Furey; Aidan P.; (Valby,
DK) ; Hansen; Palle Munk; (Bjaeverskov, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COOK MEDICAL TECHNOLOGIES LLC |
Bloomington |
IN |
US |
|
|
Assignee: |
COOK MEDICAL TECHNOLOGIES
LLC
|
Family ID: |
53489423 |
Appl. No.: |
15/150471 |
Filed: |
May 10, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/12136 20130101;
A61B 17/1204 20130101; A61B 17/12131 20130101; A61B 2017/1205
20130101; A61B 2017/00867 20130101; A61B 17/1214 20130101; A61B
17/12181 20130101; A61F 2002/823 20130101; A61B 17/12168 20130101;
A61B 17/12186 20130101; A61B 17/12113 20130101; A61B 17/12118
20130101 |
International
Class: |
A61B 17/12 20060101
A61B017/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2015 |
GB |
1508005.4 |
Claims
1. A medical filler delivery assembly for delivering filler
material into a vessel of a patient including: an elongate delivery
catheter including a proximal end, a distal end and a lumen
therein, the lumen including an exit aperture located at or
proximate the distal end of the catheter and an inlet aperture
located at or proximate the proximal end of the catheter, the lumen
being for delivery of filler material; and a positioning mechanism
including an elongate carrier including a proximal end and a distal
end, the carrier including a support element of knitted wire at the
distal end thereof and an expansion mechanism coupled to the
support element for expanding the knitted support element, the
support element being positioned or positionable adjacent the
distal end of the catheter, wherein expansion of the support
element provides a support barrier adjacent the exit aperture of
the catheter.
2. An assembly according to claim 1, wherein the support element is
formed of a plurality of wire elements intertwined one with
another.
3. An assembly according to claim 2, wherein the intertwined wires
are coupled to one another by at least one turn around one
another.
4. An assembly according to claim 2, wherein the intertwined wires
are coupled to one another by at least two turns around one
another.
5. An assembly according to claim 2, wherein the intertwined wires
are coupled to one another by at least three turns around one
another.
6. An assembly according to claim 1, wherein the knitted wire forms
a plurality of open cells delimited by wire sections.
7. An assembly according to claim 6, wherein the cells have a
polygonal shape.
8. An assembly according to claim 6, wherein the cells have a
diamond or rhomboidal shape.
9. An assembly according to claim 1, wherein the positioning
mechanism includes an elongate carrier having a proximal end and a
distal end, a tubular element slidably disposed on the elongate
carrier and including a proximal end and a distal end, and a fixing
member located at the distal end of the elongate carrier, the
support element being attached at one end to the fixing member and
at the other end to the distal end of the tubular element, wherein
sliding of the tubular element towards the fixing member causes
radial expansion of the support element.
10. An assembly according to claim 1, wherein the wires of the
support element are twisted around one another adjacent their
attachments to the tubular element and the fixing member.
11. An assembly according to claim 1, wherein the support element
includes a substantially cylindrical body portion.
12. An assembly according to claim 1, wherein the support element
includes generally conical end portions.
13. An assembly according to claim 1, wherein the support element
is radially collapsible.
14. An assembly according to claim 1, wherein the support element
is radially collapsible by longitudinal elongation thereof.
15. An assembly according to claim 1, wherein the support element
is made from stainless steel or shape memory material.
16. An assembly according to claim 1, wherein the support element
is made from shape memory alloy.
17. An assembly according to claim 1, wherein the wires of the
support element are monofilament wires.
18. An assembly according to claim 1, wherein the wires of the
support element are multifilament wires.
19. An assembly according to claim 1, including a filler storage
unit coupled to the inlet aperture of the catheter.
20. An assembly according to claim 19, including filler stored in
the storage unit.
21. An assembly according to claim 1, wherein the filler is a
filamentary material.
22. An assembly according to claim 1, including a carrier sheath
within which the delivery catheter and the positioning mechanism
are slidably disposed.
23. A method of delivering filler material into a vessel of a
patient including: positioning a distal end of an elongate delivery
catheter at a body location to be filled, the catheter including a
lumen therein for delivery of filler material and an exit aperture
at or proximate the distal end of the catheter; locating a distal
end of a positioning mechanism alongside the distal end of the
delivery catheter, the positioning mechanism including an elongate
carrier, the carrier including a support element of knitted wire at
the distal end thereof and an expansion mechanism coupled to the
support element for expanding the knitted support element, and
expanding the support element so as to provide a support barrier
adjacent the exit aperture of the catheter.
24. A method according to claim 23, wherein the distal end of the
delivery catheter is positioned into an aneurysm sac and the
support element is disposed across the aneurysm sac.
25. A method according to claim 23, including the step of expanding
the support element so as to apply pressure against the distal end
of the delivery catheter.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119(a) to Great Britain Patent Application No. GB
1508005.4, filed on May 11, 2015, which is incorporated by
reference here in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to an aneurysm treatment
assembly and in particular an assembly able to deliver into an
aneurysm sac a filler material such as, but not limited to, a
filament or coil. The invention could be used to deliver filler
material to other locations, such as into a vessel of other
cavity.
BACKGROUND OF THE INVENTION
[0003] There are several medical conditions which can benefit from
implantation into a patient of a filler material, an embolization
or other device, whether temporary or permanent. Examples include
the closure of blood vessels or other lumens. Another example for
which such procedures can be particularly useful is in the
treatment of aneurysms, where a part of a vessel wall weakens and
then expands outwardly to create an enlarged zone of the vessel,
often having the form of a sac. This vessel expansion occurs as a
result of blood pressure and tends to continue due to further and
progressive weakening of the vessel wall. If left untreated,
persistent pressure from the blood flow on the weakened wall tissue
can lead to eventual rupture of the vessel and consequential
haemorrhaging. Treatments for aneurysms have therefore focused on
reducing the pressure on the weakened vessel wall, for instance by
diverting blood flow or by isolating the weakened vessel wall, for
instance by means of a stent graft. Another treatment method
involves filling the aneurysm sac with a filler material which
stops the flow of blood into the sac and therefore stops or
substantially reduces the pressure on the weakened walls. The
filler may be an embolization coil, which will cause blood
therearound to clot and thus close the sac and provide a protective
barrier to prevent blood flowing into the sac and thereby to
prevent rupture of the weakened section of the vessel. In other
instances, the aneurysm sac may be filled with a biocompatible
material, such as a hydrogel or a polysaccharide fibre, which may
be of a biodegradable nature. A biodegradable filler performs the
same function as an embolization coil, that is to fill the aneurysm
sac and provide pressure protection to the weakened vessel walls,
with the additional advantage of allowing remodelling of the vessel
wall over time. Moreover, biodegradation of the filler will ensure
that no foreign matter remains in the patient's vessel after
conclusion of the treatment.
[0004] Such fillers and coils can also be used to close off a
vessel or other lumen in a patient.
[0005] The process of introducing such a filler or coil into a
patient can take time, particularly given that this is often
carried out remotely from the aneurysm by an endoluminal procedure.
There is also the risk that the filler material can escape from the
aneurysm sac, not only during the filling procedure but also after.
It has been postulated that this can be avoided by implantation of
a stent or stent graft across the aneurysm, though this entails
leaving in the patient a foreign object. It has also been
postulated to use a balloon to close off the aneurysm while it is
being filled but this entails the closure of the vessel, which
necessarily reduces the amount of time the balloon can remain in
the vessel.
[0006] Examples of prior art devices and methods can, for instance,
be found in US2012/0316632, U.S. Pat. No. 6,780,196, U.S. Pat. No.
8,597,320, U.S. Pat. No. 7,875,044, US2012/091171, U.S. Pat. No.
6,569,190, U.S. Pat. No. 6,312,421, US2006/0147483, U.S. Pat. No.
6,589,199 and U.S. Pat. No. 6,440,098.
SUMMARY OF THE INVENTION
[0007] The present invention seeks to provide an improved assembly
for delivering filler material into a patient and in the preferred
embodiments into a vessel or aneurysm sac.
[0008] According to an aspect of the present invention, there is
provided a medical filler delivery assembly for delivering filler
material into a vessel of a patient including:
[0009] an elongate delivery catheter including a proximal end, a
distal end and a lumen therein, the lumen including an exit
aperture located at or proximate the distal end of the catheter and
an inlet aperture located at or proximate the proximal end of the
catheter, the lumen being for delivery of filler material; and
[0010] a positioning mechanism including an elongate carrier
including a proximal end and a distal end, the carrier including a
support element of knitted wire at the distal end thereof and an
expansion mechanism coupled to the support element for expanding
the knitted support element, the support element being positioned
or positionable adjacent the distal end of the catheter, wherein
expansion of the support element provides a support barrier
adjacent the exit aperture of the catheter.
[0011] The support element, being made of wire, can be of a very
open construction allowing the continued flow of fluid, for
instance blood, within the vessel. The knitted structure of the
support element, it has been found, can impart sufficient forces on
the vessel, particularly useful in holding filler material in
place, as well as the delivery catheter, until the later has
settled in position.
[0012] In the preferred embodiment, the support element is formed
of a plurality of wire elements intertwined one with another.
Intertwining of the wires can produce an open yet strong structure.
The intertwined wires may be coupled to one another by at least one
turn around one another, preferably at least two or at least three
turns around one another.
[0013] Advantageously, the knitted wire forms a plurality of open
cells delimited by wire sections. The cells may have a polygonal
shape, for instance a generally rhomboidal or diamond shape, found
to be most efficient in terms of providing an open structure and in
terms of support strength.
[0014] In a practical embodiment the positioning mechanism includes
an elongate carrier having a proximal end and a distal end, a
tubular element slidably disposed on the elongate carrier and
including a proximal end and a distal end, and a fixing member
located at the distal end of the elongate carrier, the support
element being attached at one end to the fixing member and at the
other end to the distal end of the tubular element, wherein sliding
of the tubular element towards the fixing member causes radial
expansion of the support element.
[0015] Preferably, the wires of the support element are twisted
around one another adjacent their attachments to the tubular
element and the fixing member, able to optimise the flow of fluid
through the support element when deployed.
[0016] The support element may include a substantially cylindrical
body portion and may include generally conical end portions.
[0017] The support element is preferably radially collapsible,
advantageously by longitudinal elongation thereof.
[0018] In practical embodiments, the support element may be made
from stainless steel or shape memory material. It may be made from
shape memory alloy.
[0019] The wires of the support element may be monofilament wires
or multifilament wires.
[0020] In the preferred embodiment, the assembly includes a carrier
sheath within which the delivery catheter and the positioning
mechanism are slidably disposed.
[0021] According to another aspect of the present invention, there
is provided a method of delivering filler material into a body of a
patient including:
[0022] positioning a distal end of an elongate delivery catheter at
a body location to be filled, the catheter including a lumen
therein for delivery of filler material and an exit aperture at or
proximate the distal end of the catheter;
[0023] locating a distal end of a positioning mechanism alongside
the distal end of the delivery catheter, the positioning mechanism
including an elongate carrier, the carrier including a support
element of knitted wire at the distal end thereof and an expansion
mechanism coupled to the support element for expanding the knitted
support element, and
[0024] expanding the support element so as to provide a support
barrier adjacent the exit aperture of the catheter.
[0025] In one procedure, the distal end of the delivery catheter is
positioned into an aneurysm sac and the support element is disposed
across the aneurysm sac.
[0026] Preferably, the support element applies pressure against the
distal end of the delivery catheter when deployed.
[0027] Other aspects and advantages of the teachings herein will
become apparent form the description of the preferred embodiments
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Embodiments of the present invention are described below, by
way of example only, with reference to the accompanying drawings,
in which:
[0029] FIG. 1 is a schematic diagram of an example of a filler
delivery arrangement using a support stent;
[0030] FIG. 2 is a schematic diagram of an example of a filler
delivery arrangement using a support balloon;
[0031] FIG. 3 is a schematic diagram of an embodiment of a medical
filler delivery assembly;
[0032] FIG. 4 is a schematic diagram of an expandable knitted
support element of the assembly of FIG. 3;
[0033] FIGS. 5 to 10 show different embodiments of knitted wire
blanks for the support structure taught herein;
[0034] FIG. 11 is a is a schematic diagram of an assembly as taught
herein positioned alongside an aneurysm to be treated;
[0035] FIG. 12 is a is a schematic diagram of the assembly of FIG.
11 with the support element expanded to trap the delivery catheter
in position;
[0036] FIG. 13 is a is a schematic diagram of the assembly of FIG.
11 with the support element expanded and the delivery catheter
withdrawn; and
[0037] FIG. 14 is a is a schematic diagram of the vessel after
treatment and removal of the filler delivery assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] Various embodiments of medical filler delivery assembly are
described below and shown in the accompanying drawings. It is be
understood that the drawings are schematic only and are not
intended to show the various components of the assembly to scale.
In many cases, the assembly has been depicted in enlarged form for
the sake of clarity of disclosure. The skilled person will
appreciate that the assembly may be configured to a variety of
different sizes, and shapes, in order to correspond to the vessel
or other organ in which the device is to be deployed.
[0039] The preferred embodiments are particularly useful for the
neurovascular vessels such as the carotid artery, the vertebral
artery and so on. The invention is not so limited as the teachings
herein can be used for other body vessels.
[0040] Referring first to FIG. 1, this shows a schematic diagram of
a vessel 10 having developed an aneurysm 12, in the form of an
aneurysm sac 14 which extends to one side of the vessel 10 and
opens into the vessel 10 at its neck 16. If the aneurysm 12 is left
untreated, blood pressure will generally result in the sac 14
continuing to grow, resulting in continued weakening of the vessel
wall and eventual rupture of the vessel, leading to haemorrhaging,
with potentially serious consequences on the patient.
[0041] The treatment depicted in FIG. 1 involves delivering into
the aneurysm sac 14 one or more lengths of filamentary material 20.
The material of 20 may be platinum coil, for instance. The purpose
of the filamentary material 20 is to take up the volume in the
aneurysm sac, in other words to fill it, and as a result reduce the
amount of blood able to flow into the sac 16 and as a consequence
reduce the blood pressure on the walls of the sac 14. In the case
of the use of platinum coil or other filamentary material, the
material 14 causes an embolic reaction within the aneurysm sac, as
a result sealing the aneurysm from the flow of blood. The material
20 may not completely fill the volume inside the sac 14 and may
instead rely on embolization to fill the sac 14 completely.
[0042] The filamentary material 14 may be delivered by means of a
micro catheter 24, from a suitable source of material, not shown in
FIG. 1.
[0043] In order to hold the micro catheter 24 in place, as well as
the filamentary material 20, the example in FIG. 1 uses a stent 30
positioned across the aneurysm 12 and in particular across the neck
16. The stent 30, which may be of any suitable design, will
generally remain in place within the vessel 10 even after the
procedure. While the use of a stent 30 can provide good support for
the micro catheter 24 and retention of the distal end 25 of the
micro catheter 24 during the delivery process as well as retention
of the filler material 20 within the aneurysm sac 14, the
arrangement leaves within the body a foreign object, that is the
stent 30. While there are many medical instances where it is
advantageous to retain a stent permanently within a patient's body,
for example to keep a vessel open and stop its collapse, it is
generally preferred not to leave foreign objects within the body
for any length of time, as foreign objects can cause undesirable
side effects such as restenosis.
[0044] Referring now to FIG. 2, this shows another example of
arrangement for treating an aneurysm 12 within the wall of a vessel
10, again by delivering into the aneurysm sac 14 filamentary
material 20 via a micro catheter 24. The material 20 and micro
catheter 24 may be the same as the example of FIG. 1.
[0045] In place of a retention stent 30, the arrangement of FIG. 22
uses an expandable balloon 40 for trapping the micro catheter 24
such that its distal end remains within the aneurysm sac 14 during
the delivery process, as well as for keeping the filamentary
material 20 within the aneurysm sac 14 and preventing its
unintentional escape. The balloon 40 is typically carried on a
balloon catheter 42, which includes a suitable inflation lumen and
a port into the chamber of the balloon 40, as is well known in the
art.
[0046] The use of an inflatable balloon 40 avoids the disadvantage
of the arrangement of FIG. 1, namely of implanting into the
patient's vessel a permanent or semi-permanent foreign object.
However, the balloon 40 does not readily permit the flushing from
the aneurysm sac 14 of the fluid used to deliver the filler
material 20. Furthermore, the balloon 40 will, during the period in
which it is deployed, stop the flow of fluid through the vessel 10.
As a result of this, the filler delivery process must necessarily
be shorter, with the result that the material 20 is not trapped
within the aneurysm sac 14 by the retention mechanism (in this
instance the balloon 40) for as long as might be desirable. This
can lead to incomplete fixation of the filamentary material 20
within the aneurysm sac 14, for example as a result of incomplete
embolization of blood within the sac 14. It is known to have donut
shaped balloons 40, which have a central lumen passing though the
balloon, however lumens of this nature still create a substantial
constriction within the vessel 10.
[0047] Referring now to FIG. 3, this shows in schematic form an
embodiment of assembly for delivering filler material into an
aneurysm sac 14. The assembly 50 includes a micro catheter 24 of
similar type to that shown in the arrangements of FIGS. 1 and 2 and
which is in effect an elongate tube having a lumen therein for
feeding filler material through to its distal end 52, which in this
instance is at the extremity of the micro catheter 24. The micro
catheter 24 has a proximal end 54 which is attached to a source 56
of filler material. The source 56 includes a chamber within which
filler material can be stored and includes a feed port 58 for
coupling to a source of pressurised fluid, typically saline
solution. The filler material could be any suitable filler and in
this example is preferably a filamentary material.
[0048] The filamentary material could be of any type deemed
suitable for performing the medical function and could be sub
intestine submucosa (SIS), polysaccharide, a biocompatible
polymeric thread or other biocompatible material. Specific
examples, though the disclosure herein is not limited to these,
include: woven polyester (e.g. DACRON.RTM.), polyamide (e.g.
Nylon), expanded polytetrafluoroethylene (ePTFE; e.g.
GORE-TEX.RTM.); bioremodelable materials such as: extracellular
matrix material (ECM) for instance submucosa, renal capsule
membrane, dermal collagen, dura mater, pericardium, fascia lata,
serosa, peritoneum and basement membrane layers. Examples of
submucosa include: intestinal submucosa, including small intestinal
submucosa, stomach submucosa, urinary bladder submucosa and uterine
submucosa.
[0049] The micro catheter 24 can be used to deliver a variety of
filler materials, not necessarily only filamentary materials. The
filler could, for instance, be in the form of short lengths of
material, pellets, or the like.
[0050] The assembly 50 also includes a positioning mechanism 60
which is formed of an elongate carrier 62 having a proximal end 64
and a distal end 66. A support element 70, of knitted wire as
described in further detail below, is attached to the elongate
carrier 62 at the distal end 66. An expansion mechanism 72, 74,
described in further detail below, causes the support element 70 to
expand radially outwardly, whereupon the support element 70 presses
against the distal end 52 of the micro catheter 24 in order to hold
the latter in position, as well as providing support for any filler
material 20 which is fed into the sac 14 of the aneurysm 12, as
described in further detail below.
[0051] The elongate carrier 62 is typically formed of a catheter 80
and a wire, rod or inner catheter 82 which is slidably disposed
within a lumen of the catheter 80. Further details of the preferred
embodiment are described in connection with FIG. 4 in
particular.
[0052] As will be apparent from FIG. 3, as well as from FIGS. 5 to
7, the knitted wire support element 70 is disposed across the neck
16 of the aneurysm sac 14 during the deployment procedure and can
also be left for a period after termination of the stage in which
filler material is fed into the aneurysm sac, which can enable the
filler material 20 to settle in the sac 14, for instance but not
necessarily until embolization has occurred. For example, the wire
support element 70 can be left in place for 15 minutes or longer,
for instance up to one hour.
[0053] The assembly 50 preferably also includes an outer sheath 55
in which the delivery catheter 24 and the support member 70/80 are
held for deployment into the patient's vessel.
[0054] FIG. 4 shows an enlarged view of the knitted wire support
element 70 of this embodiment. The wire support element 70 is
formed of a plurality of wires 90 which are intertwined with one
another at junction or crossing points 92. This intertwining is
preferably in the form of wrapping of two wires 90 together for at
least one turn, though more preferably for at least two to three
turns or more of the wires, in order to tie the wires 90 to one
another. There are provided a plurality of wires 90, which extend
generally in the longitudinal direction of the support element 70,
from the distal end 94 of the support catheter 80 to the proximal
end 102 of a fixation element 100 of the expansion mechanism.
[0055] In the embodiment of FIG. 4, there are provided four pairs
of wires 90 around the circumference of the distal end 94 of the
support catheter 80 and the proximal 102 of the fixation element
100, though any other suitable number of wire pairs may be used.
The wires 90 are arranged so as to create a series of open cells
110 within the structure of the support element 70. As will be
apparent in particular from FIG. 4, the cells 110 are formed by
portions or sections of the wires 90 between the intertwined
crossing points 92. In the embodiment shown the cells have a
polygonal shape, formed by the wire sections between four crossing
points 92. The cells 110 in the embodiment of FIG. 4 could be said
to have a generally rhomboidal or diamond shape, although in other
embodiments could have a different shape.
[0056] At the ends of the support element 90, the wires are wrapped
around one another in pairs, shown at 112, so as to provide in this
embodiment four intertwined wire pairs extending generally in the
longitudinal direction of the basket 70. The wire pairs are fixed
either to the distal end 94 of the support catheter 80 or to the
proximal end 102 of the fixation element 100 in any suitable
manner, such as by tying, knotting, welding, bonding or the like.
Wrapping the ends of the wires in the manner shown at 112 in FIG. 4
gives the support structure 70 a very open configuration even at
the points at which this tapers towards the support catheter 80 and
fixation element 100. At the ends 112, the wire pairs can be
wrapped together over numerous turns, dependent primarily on the
desired length of the support element 70, its intended expanded
diameter, the degree by which it is desired to create an open
structure, the number of wires used, as well as the desired length
of the intertwined portions 112 of the wire pairs.
[0057] The support element 70 can be made of wires of stainless
steel, or a shape memory material such as Nitinol or any other
suitable material. It is also envisaged that the wires may also be
in the form of a hybrid structure which incorporates a radiopaque
element. A suitable structure may include an extruded Nitinol tube,
which envelopes a wire the outside diameter of which is equivalent
to the inside diameter of the tube. The radiopaque core could be of
any of the following: platinum, palladium, gold, tantalum or other
radiopaque material.
[0058] The wires 70 are preferably monofilament wires but in other
embodiments could be of multifilament strands. Each wire 90
preferably has a diameter in the region of 0.020 millimetres to
0.15 millimetres, preferably about 0.020 millimetres to about 0.1
millimetres, the latter being particularly suitable for
neurological applications. Practical examples used in neurological
applications had wires of 0.08 millimetres in diameter.
[0059] The structure of the support element 70 is not to be
restricted to the example shown in FIG. 4 and any other suitable
knitted wire structure may be used, other examples being shown in
FIGS. 5 to 10 described below.
[0060] The use of a knitted wire structure for the support element
70, it has been found, can be produce a structure which generates
much higher opening forces when expanded, which can as a result
provide much better retention of the distal end of the delivery
catheter 24 into an aneurysm and also much better retention of
filler material 20 within the aneurysm sac 14. Furthermore, the
open structure of the support element impinges little on the flow
of fluid, blood typically, in the patient's vessel, allowing the
support element 70 to remain deployed in the vessel for longer
periods than, for instance, a balloon based retention assembly.
[0061] The fixation element 100 may be a portion of tubing similar
to that of the support catheter 80 but which is fixed to inner
elongate element 82. The fixation element 82 could, though, be of
any structure able to hold the distal end of the support element
70. The inner elongate element 82 could be a wire, rod, micro
catheter, or any other suitable device.
[0062] The support catheter 80 is slidable on the inner elongated
element 82 and in particular towards and away from the fixation
element 100, which is fixed to the inner elongated element 82. As a
result, when the support catheter 80 is pulled back (proximally),
or similarly the inner element 82 pushed distally, the distance
between the distal end 94 of the support catheter 80 and the
proximal end 102 the fixation element 100 increases, causing the
support element 70 to elongate and in practice to contract radially
onto the inner element 82. On the other hand, when the support
catheter 80 is pushed forwards (distally), or conversely the
fixation element 100 is pulled proximally, the distance between the
distal end 94 of the support catheter 80 and the proximal end 102
of fixation element 100 shortens, which results in a shortening and
consequential radial expansion of the support element 70. The
radial expansion can be achieved by use of spring material for the
wires 90 but can equally be achieved by the relative stiffness of
the wires 90 and their knitted arrangement, which will cause the
intertwined wire cells to expand outwardly on longitudinal
compression of the element 70. Typically, the preferred embodiments
will use a combination of these two characteristics in order to
cause the support element 70 to expand radially.
[0063] It is preferred that the support element 70 has a
substantially cylindrical section or body portion having a
generally uniform diameter, with tapering ends. Other embodiments,
though, may have other shapes, for instance a generally curved
longitudinal, tapering or other profile to the body portion of the
support element 70.
[0064] FIGS. 5 to 10 show other examples of knitted structures for
the support element 70. Referring first to FIG. 5, the embodiment
shown has a plurality of wires 190 which are intertwined with one
another at junction or crossing points 192 and are also intertwined
with one another in pairs at the ends of the structure 212. In this
example, the structure differs from the example shown in FIG. 4 in
that the portions of wire 190 between junctions or crossing points
192 are substantially perpendicular to the longitudinal axis of the
frame. This provides a structure in which the cells 210 are
narrower than the example of FIG. 4, that is in which the gaps
between adjacent wire sections 190 is smaller. In a practical
example, the space between adjacent wire sections 190 may be in the
region of 0.50 mm and the overall diameter of the support
structure, when in the expanded condition is 4 mm.
[0065] Referring now to FIG. 6, this shows another example of wire
structure for the support element 70. In this embodiment, the wires
are knitted so as to create what could be described as triangular
cells 310 along the body portion of the structure, formed by the
wire portions 290 and the intertwined junction or crossing points
292. As a result, from each crossing point 292, there are two wire
portions 290 extending substantially perpendicularly to the
longitudinal axis of the frame and two wire sections extending at
an angle to the longitudinal axis, in this example at an angle of
around 55.degree. to the longitudinal axis. Again, at the ends of
the structure, pairs of wires are intertwined together as shown at
312. In this example, the gap between aligned junction points 292,
depicted by reference numeral 300 in FIG. 6, may be in the region
of 1.7 mm. the frame has, in this example, an expanded diameter of
around 4 mm.
[0066] FIG. 7 shows a structure for the support element 70 which is
very similar to the structure shown in FIG. 6, save for the fact
that the wire portions 390 extending at an angle to the transverse
axis of the structure are at an angle of around 40.degree. to the
longitudinal axis. The gap 400 between adjacent aligned crossing
points 392 is, in this example, 2.3 mm for a frame having a
diameter of around 4 mm when expanded. The wire sections 390 form
open cells 410, which are larger than the cells 310 of the example
of FIG. 6.
[0067] FIG. 8 shows another example of structure again very similar
to the structures shown in FIGS. 6 and 7, the primary difference
being the angle at which the wire sections 490 extend from the
crossing points 492, this being in the region of 35.degree. to the
longitudinal axis of the structure. As with the examples of FIGS. 6
and 7 two of the wire sections 490 extend from the crossing points
in a direction substantially perpendicular to the longitudinal
axis. In the example shown in FIG. 8, the gap 500 between adjacent
crossing points 492 is in the region of 3.1 mm for a frame having
an expanded diameter of around 4 mm.
[0068] As with the other examples, the wires are intertwined in
pairs 512 at the ends of the body portion of the frame. The
structure also has open cells 510 which are, as with the examples
of FIGS. 6 and 7, of generally uniform size along the length of the
body portion of the structure.
[0069] Referring now to FIG. 9, this shows a structure for the
support element 70 which could be described as an amalgamation of
the structures shown in FIGS. 6 to 8, specifically having
intertwined wires which provide different size cells along the
length of the structure. In this example, at the ends of the body
portion, the cells have wire portions 290 and crossing points 292
with pairs of the wires 290 having the angles of the example of
FIG. 6. Adjacent the cells 310, in a direction towards the centre
of the structure, there are cells 410 formed of wire portions 390
having the characteristics of the example of FIG. 7, whereas at the
centre of the structure, there are cells 510 formed of wire
portions 490 having the characteristics of the example of FIG. 8.
Thus, the structure shown in FIG. 9 will provide different
characteristics along its length. Where the cells are smaller, as
at the ends of the structure shown in FIG. 9, the wires will impart
a greater opening force on the vessel, whereas in the centre of the
structure of FIG. 9, the wires will impart a smaller opening force.
The skilled person will appreciate that a support structure 70
could be devised having different cell structures in an arrangement
different from that of FIG. 9 and specifically designed for a
particular clinical need.
[0070] FIG. 10 shows a wire blank similar to FIGS. 5 to 9 but which
forms the support structure 70 shown in FIG. 4. In this example,
the wire portions 90 are at an angle of around 55.degree. relative
to longitudinal axis of the structure and the gap 115 between
adjacent lined crossing points 92 is in the region of 2.2 mm for a
structure having an expanded diameter of around 4 mm.
[0071] As with all of the examples of FIGS. 5 to 10, the
intertwined wire pairs 112 at the end of the body portion will be
attached to the catheter 80 and fixation element 100 in the manner
shown in FIG. 4.
[0072] Referring now to FIG. 11, this shows the first stage of
delivery of filler material into an aneurysm 12. The distal end 25
of the micro catheter 24 is positioned within the aneurysm sac 14
and for this purpose, the distal end will usually be curved or bent
so as to facilitate its positioning within the aneurysm sac 14.
Typically, an aneurysm 12 will occur on the outside of the curved
portion of a vessel, as depicted in the Figures, which will also
assist in locating the distal end 25 of micro catheter 24 into the
aneurysm 12 as a result of the general or the tendency of the micro
catheter 24 to remain straight.
[0073] The positioning mechanism 60 is also located within the
vessel 10 such that the support element 70 extends across the
aneurysm 12 and specifically across the neck 16 of the aneurysm,
most preferably positioned so that the body portion of the support
element 70 is located adjacent to neck 16 of the aneurysm 12. At
this stage, the support element 70 is longitudinally elongated and
radially contracted, so as to sit relatively tightly over the inner
element 82, by maximising the gap between the support catheter 80
and fixation element 100.
[0074] The micro catheter 24 and positioning mechanism 60 may be
deployed into the vessel 10 at the same time, or they could be
deployed at different times, for example by positioning the micro
catheter 24 first and then inserting the positioning mechanism 60
second, or vice versa.
[0075] FIG. 12 shows the second stage of the procedure, in which
the support catheter 80 is pushed forwardly (distally), or the
fixation element 100 is pulled proximately, so as to cause the
knitted wire frame 70 of the support element to expand radially
outwardly, as shown in FIG. 12. This has the effect of trapping the
micro catheter 24 and specifically its distal end 25 in the
aneurysm 12. Trapping the distal end 25 of the micro catheter 24 in
this manner is important because the filler feeding stage,
typically carried out under pressure, will generate a rebound force
on the distal end of the micro catheter 24, which could in the
absence of retention cause the distal end 25 to move out of the
aneurysm sac 14, which would result in a failed procedure. As
explained above, the knitted, intertwined structure of the wires
forming the support element 70 can impart substantial retaining
force onto the micro catheter 24 in order to keep its distal end 25
properly in place.
[0076] The support element 70 can be repositioned during this
stage, for instance to ensure precise positioning relative to the
aneurysm 12, by stretching the support element 70 again to contract
it radially, which allows it to be repositioned prior to being
expanded again. In this manner, the support element 70 can be
positioned accurately across the neck 16 of the aneurysm 12.
[0077] Referring now to FIG. 13, with the support element or basket
70 still in the expanded condition, filler material 20, in this
example filamentary material, is fed from the source 56 through the
lumen of the micro catheter 24, out of its distal end 25 and into
the volume of the aneurysm sac 14, thereby to fill the aneurysm
sac. The amount of filler material fed into the aneurysm sac 14
will be dependent upon a number of factors. Often, the volume of
filler material will be substantially less than the volume of the
aneurysm sac as the mechanism relies upon embolization of blood
within the aneurysm sac, which is promoted by the filler material
20, to create a volume of solid material within the aneurysm
thereby to block it off from the blood flow within the vessel 10.
In some embodiments, though, the filler material 20 is injected to
a volume substantially equivalent to the internal volume of the
aneurysm sac, in which case the mechanism relies upon the filler
material 20 per se to block the aneurysm.
[0078] As explained above, retaining the support element 70 in the
expanded condition during this stage of the process ensures not
only that the distal end 25 of the micro catheter 24 remains in
place even with the back force generated by the filling pressure,
but also acts as a barrier across the neck 16 of the aneurysm 12,
in order to keep the filler material 20 within the aneurysm sac
during this stage of the process.
[0079] Once a sufficient amount of filler material 20 has been
injected into the aneurysm sac 14, the micro catheter 24 can be
removed. In some cases, the micro catheter 24 will be removed prior
to removal of the support element 70 (in which case support element
could be partially collapsed radially to remove holding pressure on
the micro catheter 24 before being expanded fully again). In other
embodiments, the micro catheter 24 and the positioning mechanism 60
can be withdrawn substantially simultaneously, in which case the
support element 70 will be regularly retracted (by pushing the
inner element 82 distally or pulling the support catheter 80
proximally or a combination of the two). This loosens the pressure
on the micro catheter 24 enabling then both components to be
withdrawn from the vessel 10.
[0080] Once withdrawn, as shown in FIG. 14, the filler material 20
remains within the aneurysm sac to close off the aneurysm 12,
whereupon blood flow through the vessel 10 regains a natural flow
as if the aneurysm did not exist.
[0081] With reference to FIGS. 12 and 13, it can be seen that the
open structure of the support element 70, even when expanded within
the vessel 10, provides little restriction to the flow of blood
through the vessel 10, enabling the assembly to be used in a large
variety of vessels for treating aneurysms and also allowing a
longer procedure to ensure proper occlusion of an aneurysm without
having to compromise in respect of deployment times. Moreover,
effective support can be provided during the aneurysm occlusion
process without the need for a permanent implant in the form of a
vascular stent, flow diverter or the like. The open structure of
the support element 70 also means that it can be disposed across
branch vessels as blood can flow through the open cells 110 as well
as in the longitudinal direction of the support element 70.
[0082] It will be appreciated that the use of a wire basket also
allows flushing fluid to be expelled from the aneurysm sack 14
during the delivery of the filler material 20, which enables more
filler material 20 to be administered into the aneurysm sack
14.
[0083] The embodiments described above have a support structure 70
formed of a single layer of knitted wires. Other embodiments may
have two layers of knitted wires, one interposed over the other and
preferably off-set, such that the open cells of one knitted wire
layer are positioned above or below (respectively) the wire
portions of the overlying or underlying wire layer. As a result,
the openings within the double structure can be smaller. In such
examples, the wires may be of a smaller diameter than those used
for a single layer knitted structure.
[0084] In the embodiments described above, the knitted wire
structure 70 is formed of eight wires which are knitted together.
Other embodiments may use a different number of wires, for example
12 or 16 wires or more and equally with fewer wires, such as six.
These would similarly be arranged in pairs of wires at the ends,
although it is not excluded that three or more wires could be
intertwined together at the ends of the structure rather than being
intertwined in pairs as shown in the embodiments described
above.
[0085] The embodiments described above use a support structure 70
formed solely of wires. It is envisaged, though, that in some
embodiments there may be provided a sleeve disposed over the wire
structure, formed of a porous fabric material, such as an
ultra-high molecular weight polyethylene, for instance Dyneema.TM..
It is preferred that such a sleeve is made of stretchable material.
The sleeve will be open at its ends to allow fluid to pass through
the structure during the deployment of the device.
[0086] All optional and preferred features and modifications of the
described embodiments and dependent claims are usable in all
aspects of the invention taught herein. Furthermore, the individual
features of the dependent claims, as well as all optional and
preferred features and modifications of the described embodiments
are combinable and interchangeable with one another.
[0087] The disclosure in the abstract accompanying this application
is incorporated herein by reference.
* * * * *