U.S. patent application number 14/969277 was filed with the patent office on 2016-06-16 for vascular plug.
The applicant listed for this patent is COOK MEDICAL TECHNOLOGIES LLC. Invention is credited to Tue Thuren Bodewadt, Christina Rauff Hansen.
Application Number | 20160166259 14/969277 |
Document ID | / |
Family ID | 47843556 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160166259 |
Kind Code |
A1 |
Bodewadt; Tue Thuren ; et
al. |
June 16, 2016 |
VASCULAR PLUG
Abstract
A vascular plug for implantation into a patient's vessel
includes an inflatable balloon and a flow accelerator. The flow
accelerator includes a conical portion and a tubular coupling
element which couples the conical portion to an aperture to the
interior of the inflatable balloon. The flow accelerator will
concentrate and therefore accelerate fluid flow into the inflatable
balloon. Flow accelerator will increase the pressure of fluid
thereby to cause the inflatable balloon to inflate even within a
pressurised blood vessel. The plug may include a sleeve which
provides a chamber between the flow accelerator and the balloon,
into which blood may pass from the inflatable balloon or the flow
accelerator to create additional blood statis and as a result
thrombosis and a second occlusive barrier.
Inventors: |
Bodewadt; Tue Thuren;
(Solroed Strand, DE) ; Hansen; Christina Rauff;
(Koebenhavn, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COOK MEDICAL TECHNOLOGIES LLC |
Bloomington |
IN |
US |
|
|
Family ID: |
47843556 |
Appl. No.: |
14/969277 |
Filed: |
December 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13803504 |
Mar 14, 2013 |
9259227 |
|
|
14969277 |
|
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|
Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61B 17/12109 20130101;
A61B 17/12136 20130101 |
International
Class: |
A61B 17/12 20060101
A61B017/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2013 |
GB |
1300930.3 |
Claims
1. A vascular plug for occluding a body vessel, the plug
comprising: an inflatable element provided with an aperture, the
aperture comprising a one-way valve; and a flow accelerator
including first and second ends, the first end providing a greater
flow area than a flow area of the second end, the second end being
coupled to the aperture of the inflatable element.
2. The vascular plug according to claim 1, wherein the flow
accelerator is generally conical.
3. The vascular plug according to claim 1, wherein the flow
accelerator includes a conical portion.
4. The vascular plug according to claim 3, wherein the flow
accelerator includes a cylindrical portion attached to the first
end of the conical portion.
5. The vascular plug according to claim 1, wherein the second end
of the flow accelerator provides or includes a neck.
6. The vascular plug according to claim 5, wherein the neck
includes a tubular neck section.
7. The vascular plug according to claim 1, wherein at least one of
the inflatable element and the flow accelerator is made of an
expandable or elastic material.
8. The vascular plug according to claim 1, wherein at least one of
the inflatable element and the flow accelerator is made of an
inextensible material.
9. The vascular plug according to claim 1, wherein at least one of
the inflatable element and the flow accelerator is made of a
material from the group including: polyurethane, polyamide,
polyether block amide, silicone and thermoplastic elastomers.
10. The vascular plug according to claim 1, wherein the inflatable
member has a diameter and a length, and wherein its length is less
than its diameter.
11. The vascular plug according to claim 1, wherein a portion of
the flow accelerator has a cross-sectional shape which is
substantially circular.
12. The vascular plug according to claim 1, wherein the inflatable
element comprises a wall, and the one-way valve comprises a flap of
material attached to the wall of the inflatable element, the flap
having a larger diameter than the aperture of the inflatable
element.
13. The vascular plug according to claim 12, wherein the flap is
made of the same material as the inflatable element.
14. The vascular plug according to claim 1, further comprising at
least one anchoring element extending radially outward from the
first end of the flow accelerator.
15. The vascular plug according to claim 14, wherein the at least
one anchoring element comprises a barb comprising a point, the
point being oriented toward the second end of the flow
accelerator.
16. The vascular plug according to claim 15 comprising a plurality
of anchoring elements arranged circumferentially around the first
end of the flow accelerator.
17. The vascular plug according to claim 1, wherein the flow
accelerator further comprises at least one self-expanding
strengthening element for assisting in deployment of the vascular
plug and maintaining the shape of the vascular plug in situ.
18. The vascular plug according to claim 17, wherein the
strengthening element comprises a frame.
19. The vascular plug according to claim 17, wherein the
strengthening element comprises a shape memory alloy.
20. A vascular plug for occluding a body vessel, the plug
comprising: an inflatable element provided with a aperture; and a
flow accelerator including first and second ends, the first end
providing a greater flow area than a flow area of the second end,
the second end being coupled to the aperture of the inflatable
element; wherein the aperture does not include a valve.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/803,504, now allowed, filed Mar. 14, 2013,
which is related to and claims the benefit of priority to GB
1300930.3, filed on Jan. 18, 2013, which is incorporated herein by
reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to a vascular plug or occluder
for closing a body vessel.
BACKGROUND ART
[0003] Vascular occluders have been known for a number of years.
Many types are in the form of a device which is implanted within a
vessel of the patient and which has a structure which closes off
the vessel so as to occlude blood flow. Occluders of this nature,
sometimes referred to as vascular plugs, are preferable over more
traditional forms of occluder, such as vascular constrictors, which
generally require an invasive medical procedure. Vascular
occluders, on the other hand, can be deployed endoluminally in a
significantly faster and less traumatic medical procedure.
[0004] Vascular occluders may be designed or used to provide
temporary occlusion, for example to be effective only for the
duration of a medical procedure or during a period of treatment.
Occlusion may also be permanent, in which case the occluder will be
left within the patient indefinitely.
[0005] There are generally two types of vascular occluders. The
first type promotes embolization within the vessel, for instance by
slowing the flow of blood through the device and in some cases with
the addition of embolization promoters. Such devices do not produce
immediate occlusion of the vessel as they rely upon the formation
of sufficient blood clotting to act as the occluding barrier.
Sufficient thrombosis can take hours, days or even weeks in some
instances.
[0006] Another type of vascular occluder has an impervious element,
typically a membrane, attached to a supporting structure which
gives it a conical shape. The wide end of the device expands to
spread across the entire diameter of the vessel and thus creates an
instantaneous barrier to blood flow. Other examples provide an
inflatable balloon or chamber, which is filled with fluid to expand
the balloon or chamber and thereby cause it to fill the diameter of
the vessel in which the balloon or chamber is placed, thereby
closing off the vessel. In many cases immediate occlusion of this
type is preferable. However, some designs of such occluders do not
reliably counter the full force of the blood stream, leading to
migration of the device, loss of positional orientation, failure to
achieve a full seal against the vessel wall and thus failure of the
device. Furthermore, some such devices can fail to deploy properly
in the vessel, leading to them being ineffective from the
start.
[0007] In addition to difficulties in accurate placement and risk
of migration, an occluder may also leak or become dislodged if the
vessel changes size or shape over time. Such size or shape change
can lead to loss of connection to the vessel wall.
[0008] Some examples of known vascular occluders can be found in
U.S. Pat. No. 6,638,293 and US-2008/0221600.
BRIEF DESCRIPTION OF THE INVENTION
[0009] The present invention seeks to provide an improved vascular
plug or occluder. The preferred embodiments provide an occluder of
which at least a part is impervious so as to create substantially
immediate occlusion of a vessel. In some embodiments, the vascular
occluder also includes a permeable element designed to provide a
region of stagnant blood to promote embolization.
[0010] According to an aspect of the present invention, there is
provided a vascular plug for occluding a body vessel, the plug
including an inflatable element provided with an aperture, and a
flow accelerator including first and second ends, the first end
providing a greater flow area than a flow area of the second end,
the second end being coupled to the aperture of the inflatable
element.
[0011] This structure provides an inflatable device, for instance a
balloon, which when inflated can close off a vessel so as to
occlude it. The flow accelerator has the effect of increasing the
fluid flow and thus pressure thereof into the inflatable member.
This can enable the chamber to be inflated by the blood stream
alone without the need for a separate inflation mechanism.
Moreover, the structure can allow for the inflatable element to be
continually subjected to inflation pressure, through the flow
accelerator, thereby to expand with any expansion of the vessel,
thereby to maintain reliable occlusion of the vessel.
[0012] In the preferred embodiment, the flow accelerator, or
concentrator, is conical. In another embodiment, the flow
accelerator includes a conical portion and preferably a cylindrical
portion attached to the first end of the conical portion.
[0013] In the preferred embodiment, the device includes a one-way
valve at the aperture of the inflatable element. Some embodiments
can have a permanently open aperture to the inflatable element,
relying on constant pressure from the patient's blood stream
pressure to keep the inflatable element under pressure. However, it
is preferred that there is provided a one-way valve, which
maintains fluid and thus pressure inside the inflatable element and
therefore maintains the element's inflated diameter even when there
is a drop off in blood pressure, for example once thrombosis has
occurred upstream of the vascular plug, between heat beats, during
fluid back flow and so on. It will be apparent that the one-way
valve is configured to allow fluid into the inflatable member and
to block fluid flow out of the inflatable member.
[0014] The second end of the flow accelerator provides or includes
a neck, which may include a tubular neck section. A coil may be
provided in the neck section, advantageously having an internal
coil surface providing a threaded coupling. The coil can provide a
coupling thread for a delivery detach mechanism, providing a
convenient and reliable deployment structure for the plug.
[0015] At least one of the inflatable element and the flow
accelerator may be made of an expandable or elastic material. In
another embodiment, at least one of the inflatable element and the
flow accelerator is made of an inextensible material.
[0016] The inflatable element and/or the flow accelerator is made
of a material from the group including: polyurethane, polyamide,
polyether block amide, silicone and thermoplastic elastomers.
[0017] Use of an expandable or elastic material for the inflatable
element and/or flow accelerator enables the device to attain a
fully deployed configuration over a range of diameters, in contrast
with devices made of non-elastic material which may remain only
partially deployed, in particular to be partly folded when in situ.
An expandable or elastic inflatable element can apply a constant
force against the vessel wall, thereby ensuring good patency and a
good grip to the vessel wall. It is not always practicable to match
a device size precisely to a vessel diameter, at least for the
reasons given above.
[0018] Advantageously, there may be provided a sleeve disposed
outside of and between the first end of the flow accelerator and
the inflatable member. The sleeve preferably provides a fillable
chamber. In practice, the chamber may be blood fillable, to store
stagnant blood which will tend to coagulate into a thrombus and
therefore provide an additional occluding barrier. In this regard,
there may be provided one or more fluid outlets in the inflatable
element coupling into the fillable chamber, thereby to pass blood
from the inflatable element into the cylindrical chamber.
[0019] In another embodiment, there may be provided a generally
conical fillable chamber around the flow accelerator, which may
take the form of a closed conical membrane disposed radially
outside of the flow accelerator. Such a chamber can provide a
support structure, formed by filling the space between the flow
accelerator and the membrane with blood. The blood will over time
coagulate within the chamber, thereby to provide in effect a
thickening and strengthening of the wall of the flow
accelerator.
[0020] In an embodiment, the flow accelerator is at least partially
permeable.
[0021] There may be provided one or more fluid outlets in the
inflatable element. Advantageously, the one or more fluid outlets
are disposed in a part of the inflatable element which faces
upstream, in practice in a part of the inflatable member facing the
flow accelerator. In this embodiment, the device may include, as
previously explained, a sleeve coupling an outer perimeter of the
flow accelerator with an outer perimeter of the inflatable member
to create a chamber between the inflatable member and the flow
accelerator, the one or more outlets connecting the interior of the
inflatable element to the chamber. With this structure, it is not
necessary for there to be a passage for blood from an upstream
direction, typically from the flow accelerator. The outlet or
outlets will assist in the creation of a volume of static blood in
the device and thus in the promotion of thrombosis.
[0022] In an embodiment, the device may include two flow
accelerators in opposing relationship either side of the inflatable
member, both flow accelerators being coupled to a respective
aperture in the inflatable member. Such a two way plug may be
filled from either side. Advantageously, the inflatable member
includes a one-way valve at each aperture.
[0023] Preferably, the inflatable member has a diameter which is
greater than its length.
[0024] According to another aspect of the present invention, there
is provided a method of occluding a body vessel, including the
steps of:
[0025] providing a vascular plug, the vascular plug including an
inflatable element provided with an aperture; and a flow
accelerator including first and second ends, the first end
providing a greater flow area than a flow area of the second end,
the second end being coupled to the aperture of the inflatable
element;
[0026] locating the vascular plug in a body vessel with the first
end of the flow accelerator facing a direction of fluid flow such
that fluid from the fluid flow enters the flow accelerator and
thereby to cause inflation of the inflatable element and occlusion
of the body vessel.
[0027] In the case where the vascular plug includes opposing flow
accelerators, the method includes the step of placing the vascular
plug in a body vessel such that the first end of one of the flow
accelerators faces the blood flow. The first end of the other flow
accelerator would thus face downstream of the blood flow.
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 side elevational view first embodiment of
vascular plug;
[0030] FIG. 2 is a longitudinal cross-sectional view another
embodiment of vascular plug;
[0031] FIG. 3 is a side elevational view an embodiment of double
ended vascular plug;
[0032] FIG. 4 is a longitudinal cross-sectional view another
embodiment of double ended vascular plug;
[0033] FIG. 5 is a side elevational view another embodiment of
vascular plug;
[0034] FIG. 6 is a side elevational view yet another embodiment of
vascular plug; and
[0035] FIG. 7 is a photograph of a prototype vascular plug produced
in accordance with the teachings herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Referring to FIG. 1, there is shown a first embodiment of
plug 10 according to the present invention. The view shown is a
side elevational view in partial cross-section. The plug includes
an inflatable element 12 which could be described as a balloon,
which may be made of conventional balloon material such as
polyurethane, polyamide such as Nylon, polyether block amide such
as Pebax, or any other suitable material. In the preferred
embodiment, the material of the inflatable element 12 is an
expandable or elastic material such as silicone or a thermoplastic
elastomer.
[0037] The inflatable element 12 is in transverse cross-section, in
practice perpendicular to the vessel and direction of fluid flow as
shown by the arrow in FIG. 1, generally circular so as to have a
shape consistent with the cross-sectional shape of the vessel. The
inflatable member element 12 may have a transverse diameter, normal
to the direction of flow, which is greater than its length, as can
be seen in FIG. 1. In other embodiments, though, the inflatable
element 12 may be longer and may, for instance, be longer than it
is wide.
[0038] The inflatable element 12 has at least one aperture 14 which
is connected to an end of a flow accelerator 16. In this
embodiment, the flow accelerator 16 has a conical portion 18, which
serves to concentrate and accelerate flow of fluid along its
length. A tubular connector portion 20 fluidically connects the
narrow end of the conical portion 18 of the flow accelerator to the
aperture 14 in the inflatable element 12. Typically, the aperture
14 will be substantially round and located at the centreline or
close to the centreline of the device 10 and thus of the radial and
axial centre of the inflatable element 12
[0039] The flow accelerator 16 has, in the preferred embodiment, a
round wide end 22 and is round in transverse across-section for the
whole of its length to its narrow end, although it is not essential
that it is entirely round. The structure is such that there is a
direct flow path from the wide end 22 of the flow accelerator 16
into the interior chamber 24 of the inflatable element 12.
[0040] The flow concentrator 16, including the conical portion 18
and the tubular connector 20, are preferably made of the same
material as the inflatable element 12 but may be made of a
different material. In the preferred embodiment, the inflatable
element 12 and the flow concentrator 16 are made of impermeable
materials, but it is not excluded that one or both may be partially
permeable, as described below.
[0041] It will be appreciated that the tubular connector 20 is not
a necessary component of the structure of plug 10 shown in FIG. 1,
as the narrower end of the conical portion 18 of the flow
accelerator 16 could be coupled directly to the aperture 14 of the
inflatable element 12.
[0042] The plug 10 is designed to be disposed in a patient's vessel
with the wide end 22 of the flow accelerator 16 facing upstream so
as to be opposite the direction of fluid flow and the inflatable
element 12 downstream of this. Both the edges of the wide end 22 of
the flow accelerator 16 and the circumferential periphery of the
inflatable element 12 will be in contact with the vessel wall.
[0043] It will be appreciated that the longitudinal separation 26
between the wide end 22 of the flow accelerator 16 and the point of
greatest diameter of the inflatable element 12 (its circumferential
periphery) creates two spaced contact and support points for the
plug 10 within the vessel. These support points assist in
maintaining the plug 10 correctly oriented and in position in the
vessel, and minimise the risk of the plug 10 tilting in the vessel,
as can occur with prior art plug structures.
[0044] Once located in a vessel, fluid flowing towards the plug 10
will pass into the flow accelerator 16 and accelerate as a result
of the taper of the conical portion 18, until it eventually passes
through the tubular connector 20 and into the inflatable element
12. The increase of the flow speed will create an effective
increase in fluid pressure leading into the inflatable element 12,
thereby causing the element 12 to inflate. Continued pressure of
blood flow in the patient's vessel will continue to urge blood into
the flow accelerator 16 and thus into the inflatable element 12.
This keeps the inflatable element 12 in an inflated condition and
also acts to cause this to expand further if there is any expansion
of the vessel over time. The structure therefore provides a
self-deploying plug assembly which can maintain a continuous
expansion pressure of the inflatable element 12 against the vessel
wall in order to retain the plug 10 in position and properly sealed
to the vessel wall.
[0045] The flow accelerator 16 may be provided with strengthening
elements (not shown) which may be in the form of a frame of
resilient material, for instance a shape memory alloy such as
Nitinol. The frame will assist in the deployment of the flow
accelerator 16 and help hold the shape of the flow accelerator 16
when in situ.
[0046] The plug 10, and in particular the inflatable element 12 and
the flow accelerator 16, are compressible, typically by wrapping
and folding, so they can be delivered by a conventional introducer
assembly endoluminally through the vasculature of a patient. In
practice the device 10 would be radially compressed often by
wrapping on to a carrier and then disposed within a sheath or
catheter of an introducer assembly for deployment in a patient.
Once released from the introducer assembly, the plug 10 will
expand, often both as a result of the resilient nature of the
materials used for the plug 10 and also as a result of the pressure
of blood within the patient's vessel.
[0047] Also shown in FIG. 1 is an optional sleeve 28 which extends,
in this embodiment, from the wide end 22 of the conical portion 18
of the flow accelerator 16 to the inflatable element 12, adjacent
to the point of widest perimeter or radius thereof. Typically, the
sleeve 28 will be fixed to or integral with the conical portion 18
of the flow accelerator 16 and to the inflatable element 12. The
sleeve 28, which is generally cylindrical and round in transverse
cross-section, may be made of the same material as the inflatable
element 12 but could be formed of other materials, whether
impervious or permeable.
[0048] The sleeve 28 creates a chamber 30 between the inflatable
element 12 and the flow accelerator 16, within the longitudinal
extent of the plug 10. The chamber 30 is designed to hold
substantially stagnant blood therein, which in the course of time
will clot to create a thrombus, acting as an additional occlusive
barrier. Blood can be made to pass into the chamber 30 in a number
of ways, such as by one or more holes within the wall of the flow
accelerator 16, one or more holes within the wall of the inflatable
element 12, which holes couple directly into the chamber 30. In
another embodiment, at least a part of flow accelerator 16 is made
of a porous or substantially porous material, of porosity
substantially less than the expected flow of blood, thereby to
ensure that the accelerator 16 still concentrates and accelerates
fluid into the inflatable element 12 while providing for some fluid
to pass into the chamber 30.
[0049] Referring now to FIG. 2, there is shown another embodiment
of plug 40, generally very similar to the embodiment of plug 10
shown in FIG. 1. The plug 40, as the embodiment of FIG. 1, includes
an inflatable element 12, a flow accelerator 16 including a conical
portion 18 and a tubular connector 20, as well as a sleeve 28
providing a chamber 30 between the flow accelerator 16 and the
inflatable chamber 12. As the embodiment of FIG. 1, the sleeve 28
and tubular connector 20 are preferable but not necessary.
[0050] In the embodiment of FIG. 2, there is provided a one-way
valve 42 at the aperture of the inflatable element 12. The valve 42
opens in the direction of fluid flow 44 but closes in the opposite
direction, in other words opens in a direction of filling of the
inflatable element 12 but closes in a direction of emptying of the
inflatable element 12. Thus, the one-way valve 42 enables the
inflatable element 12 to be filled and ensures it cannot be
emptied. In this manner, the amount of fluid within the inflatable
element 12 and therefore its size when inflated will not be reduced
even upon loss of pressure of fluid from the flow accelerator
16.
[0051] This can be particularly useful when the plug 10 is to be
deployed in a part of the patient's vasculature which is subject to
large pressure variations and fluid back flow. The one-way valve
could be provided as a part of the wall of the inflatable element
12, as part of the tubular connector 20 (or the conical portion 18
where the tubular connector 20 is not provided) or as a separate
element. In its simplest form, the one-way valve can be a flap of
material, possibly the same material as that of the wall of the
inflatable element 12, connected to the wall of the inflatable
element 12 and which has a diameter larger than the hole 14.
[0052] The embodiment of FIG. 2 also includes a series of anchoring
elements 46 extending radially outwardly from the wide end 22 of
the flow accelerator 16, which may be in the form of barbs. These
may be substantially evenly spaced circumferentially around the
wide end 22 of the flow accelerator 16. As will be appreciated from
FIG. 2, the anchors 46 preferably point backwards towards the
distal end of the plug 10 and in practice in the direction of fluid
flow 44, thus opposite the direction of force produced by the fluid
flow 44.
[0053] The anchoring elements 46 may usefully be formed as a part
of the strengthening elements of a frame of the flow accelerator
16. The anchoring elements 46 assist in holding the plug 40 in
position in the vessel wall and minimise the risk of migration of
the plug 40 as a result of the pressure from the blood flow 44.
[0054] Instead of or in addition to anchoring elements 46, the
plugs disclosed herein may be provided with other measures to
reduce the risk of migration of the plug within the vessel,
including, for example, texturing or roughening of the surface of
the inflatable element 12 which contacts the vessel wall.
[0055] It is to be appreciated that the anchoring elements 46 and
the one-way valve 42 may be provided also in the embodiment of FIG.
1 and in any of the other embodiments disclosed herein and covered
by the claims.
[0056] Referring now to FIG. 3, there is shown another embodiment
of plug 50 having the general features of the embodiments of FIGS.
1 and 2, that is an inflatable element 12 coupled to a first flow
accelerator 16 intended to be arranged to face the upstream
direction of fluid flow 44 within a patient's vessel. The plug 50
of FIG. 3 also includes a second conical flow accelerator 56
disposed on the opposite side of the inflatable element 12 and
having the same characteristics and structure of the flow
accelerator 16, the only difference being its position and
orientation in the device 50.
[0057] The inflatable element 12 includes a second aperture 54
which couples to the opening in the narrow end of the flow
accelerator 56. Thus, the inflatable element 12 includes apertures
14, 54 both in the upstream and in the downstream direction of
fluid flow 44. The plug 50 also includes first and second one-way
valves 42, 52 disposed to overlie the apertures 14, 54 into the
inflatable element 12. Thus, when fluid flows in the direction of
arrow 44 shown in FIG. 3, the one-way valve 52 will close, whereas
a one-way valve 42 open, to enable fluid to fill the inflatable
element 12. On the other hand, the fluid flows in the opposite
direction, that is opposite the direction of arrow 44 of FIG. 3,
for example when there is back-flow of fluid within the vessel, the
valve 42 will close, whereas the valve 52 will open. This reverse
fluid flow will thus still contribute to filling the inflatable
element 12. As a result, the inflatable element 12 of the plug 50
will be filled whatever direction fluid is flowing to the plug 50
and, similarly, whichever way the plug 50 is deployed in the
vessel.
[0058] It will be appreciated that the one-way valves 42 and 52 can
have the same structures and be made of the same materials.
[0059] FIG. 4 shows an embodiment of plug 60 similar in structure
to the plug 50 of FIG. 3, which includes in addition first and
second sleeves 28, 68 each extending between the inflatable element
12 and the wider end of its respective flow accelerator 16, 56. The
sleeves 28 and 68 create two chambers 30, 70 either side of the
inflatable element 12. The sleeve 68 is preferably the same
structure and has the same characteristics as the sleeve 28 and as
described above.
[0060] Also shown in FIG. 4 are holes 62, 64 in the wall of the
inflatable element 12, which allow passage of fluid (blood) from
the interior 24 of the inflatable element 12 to their respective
chambers 30, 70 for filling the latter with fluid when the device
60 is implanted in a body vessel.
[0061] Thus, the embodiment of plug 60 shown in FIG. 4 can create
in effect three zones of stagnant blood, namely the interior 24 of
the inflatable element 12 and in the chambers 30, 70 formed by the
sleeves 28, 68. It will be appreciated that these chambers, as with
the other embodiments described herein, are in addition to a zone
of stagnant blood which will be created within the flow
accelerators 16, 56 once the inflatable element 12 has been fully
inflated and allow no further flow of blood thereinto. These
volumes of stagnant blood will tend to promote thrombosis and thus
a creation of further occlusion barriers.
[0062] Referring now to FIG. 5, there is shown another embodiment
of plug 80. This embodiment has a number of elements consistent
with the above-described embodiments and including, for example,
the inflatable element 12, the flow accelerator 16, tubular
connecting element 20 and, optionally, one-way valve 42. These
elements all have the characteristics described herein.
[0063] The embodiment of plug 80 shown in FIG. 5 has in addition a
second fillable element 82 which in this example is a second cone
lying radially outside of and concentric with the conical portion
18 of the flow accelerator 16. The second cone 82 has an open end
83 of greater diameter than the open end 22 of the flow accelerator
16 and a closed end 84, which in this example closes around the
tubular connector 20. The second cone 82 is preferably made from a
similar material as that forming flow accelerator 16 and may be
provided with strengthening elements such as a frame as disclosed
above.
[0064] The difference in diameters at the open ends of the two
cones 18 and 82 and along their lengths create an annular space 86
for receiving blood from the volume of blood within the vessel. As
blood fills this space between the two cones it creates, together
with the material of the walls of the cones, a self-supporting
structure which presses against the vessel wall and holds the plug
80 tightly against the vessel wall. In the described embodiment,
the space between the outer cone 82 and the wall of the flow
accelerator 16 is sealed save for the annular aperture 86. Thus,
blood will stagnate and coagulate over time to create a conical
occlusive barrier which will be consistently biased open by the
pressure of blood flow 44.
[0065] In the embodiment of FIG. 5, the walls of the flow
accelerator 16 may be impermeable or may permeable, at least
partially, in order to promote filling the space between the two
cones 82, 18.
[0066] FIG. 6 shows another embodiment of plug 90 having
characteristics similar to the embodiment of FIG. 5 as well as the
embodiment of FIG. 3. More specifically, the embodiment of FIG. 6
shows a double ended plug 90 similar to plug 50 of FIG. 3 but in
which there is provided an additional cone 82 and 92 over each flow
accelerator 16, 56, of the characteristics shown in FIG. 5 and
described above. The embodiment of FIG. 6 may have all of the
features of the other embodiments described herein.
[0067] It will be appreciated that the creation of a conical volume
of clotted blood between the two cones 82, 18 may establish the
shape of the flow accelerator 16 without the need to rely upon any
sprung elements to maintain the flow accelerator 16 open.
[0068] FIG. 7 shows a photograph of a prototype vascular plug 90
produced in accordance with the teachings herein. The plug 90,
which has or can have the features taught herein, includes an
inflatable balloon element 92 and a flow accelerator 94 coupled to
the inflatable balloon 92. The flow accelerator 94 includes a
conical portion 96 and a cylindrical portion 98 extending from the
wide end of the conical portion 96. The cylindrical portion helps
stabilise the device 90 in a patient's lumen and improves patency
of the device to the vessel walls. To optimise the fitting of the
device to the vessel wall, there may be provided a stent ring 100
or other support in the cylindrical section 98, which may be
provided on an internal surface of the cylindrical section 98, on
an outside surface thereof or embedded in the wall thereof. Any
other strengthening element may be provided.
[0069] Also shown in FIG. 7, in schematic form, is a coil 102 which
in this example is disposed in the tubular section between the
inflatable balloon 92 and the flow accelerator 94. The coil 102 has
its internal surfaces protruding into the inside of the tubular
coupling section and in practice provided a threaded connector,
which can couple to a threaded detach tool of a deployment
assembly. Thus, the plug 90 can be reliably connected to a
deployment assembly, positioned in the desired location in a
patient's vasculature and then separated form the deployment
assembly by a simple unscrewing action.
[0070] With regard to deployment of the plug taught herein, in all
embodiments it is envisaged that this can be achieved by means of a
standard introducer assembly in which the plug is radially
constrained, for example by compression and/or wrapping around a
carrier element, into the sheath of an introducer assembly, for
delivery endoluminally through the vasculature of a patient. Once
released from the introducer assembly, the plug will expand
radially outwardly against the vessel walls, with the flow
accelerator filling the interior of the inflatable element 12 to
cause this to create an occluding barrier and to engage itself with
the vessel walls. The structure thus creates substantially
immediate occlusion of a vessel and occlusion which can be
maintained over time, even when the vessel changes dimensions or
shape.
[0071] The interior 24 of the inflatable element 12 will create
blood statis which will promote clotting, as will the other regions
around the inflatable element 12 which hold blood substantially
stagnant within the vessel. The device can thus produce permanent
occlusion of a vessel.
[0072] The flow accelerator 16 may be made simply as one or more
layers of a flexible and/or elastomeric polymer material and may
include, as explained above, strengthening elements or a frame. The
strengthening elements or frame may be self-expandable to assist in
the initial expansion of the flow accelerator 16 within the patient
following its release from the introducer assembly. A frame of this
nature can be of spring or shape-memory material such as a
shape-memory alloy, typically Nitinol.
[0073] It will be appreciated, particularly with regard to the
embodiments of FIGS. 3, 4 and 6, that these could be delivered over
the wire, that it is by means of a guide wire of the type often
used for the endoluminal deployment of medical devices. In this
regard, a guide wire can be passed through the structure of FIGS.
3, 4 and 6, that is across the one-way valves of the inflatable
element 12 and through the flow accelerator 16, 56. The valves 42,
52 will be opened to allow the passage of the guide wire and will
close once the guide wire has been removed from the plug.
[0074] Similar provision may be made with regard to the embodiments
having only a single flow accelerator, that is the single-sided
embodiments of FIGS. 1, 2 and 5. This can be achieved by providing
an additional one-way valve in the inflatable element 12, similar
to the one-way valve 42 of the embodiments of FIGS. 3, 4 and 6. The
one-way valve in this circumstance could be opened to allow the
passage of the guide wire through the inflatable element 12 but
will close once the guide wire has been removed. The one-way valve
would remain closed after the removal of the guide wire. The
balloon wall at the one-way valve could be made material than the
balloon wall at other locations of the balloon, in order to support
a valve or the tubular element.
[0075] In other embodiments, the valve may be a self-sealing slit
valve.
[0076] The embodiments of FIGS. 5 and 6 could be provided with
external sleeves as in the embodiments of FIGS. 1, 2 and 4.
[0077] It is to be understood that the embodiments described above
with reference to the accompanying drawings are only some of the
embodiments of the invention and that others will be apparent to
the person skilled in the art which will fall within the scope of
the claims. It is to be appreciated also all of the features of the
different embodiments described above may be combined with one
another and are not exclusive of one another.
* * * * *