Note: Descriptions are shown in the official language in which they were submitted.
WO 2011/064784 PCT/IL2010/001001
METHOD OF IMPLANTING A STENT GRAFT
AND CREATING A FENESTRATION THEREIN
FIELD OF THE INVENTION
[001] This invention is directed to a method for creating a fenestration in a
stent graft at the
point where the main vessel in which the stent graft is placed branches into a
side branch
vessel.
BACKGROUND OF THE INVENTION
[002] An aneurism is a localized, blood-filled balloon-like bulge of a blood
vessel, caused by
the weakening of the vessel wall. One type of aneurism is an aortic aneurism,
which occurs in
the main artery carrying blood from the left ventricle of the heart to the
body. When the size of
an aneurism increases, there is a significant risk of rupture, resulting in
severe hemorrhage,
which may even lead to death. Aneurisms may be hereditary or caused by
disease, either of
which can lead to the weakening of the blood vessel wall.
[003] For aneurysms in the aorta, arms, legs or head, the weakened section of
the vessel may
be replaced by a bypass graft that is sutured at the vascular stumps. Instead
of sewing, the graft
tube ends, which are made rigid and expandable by a nitinol wireframe, can be
inserted into the
vascular stumps and permanently fixed there by external ligature or an
expandable ring. Less
invasive endovascular techniques allow covered metallic stent grafts to be
inserted through the
arteries of the leg and deployed across the aneurysm.
[004] Thus, when the aneurism occurs in a region of a blood vessel where there
is no
branching leading to other blood vessels, stent grafts may be easily placed,
thereby bypassing
the aneurism and highly reducing the risk of rupture. However, when the
aneurism occurs in
the close vicinity of another blood vessel that branches off from the vessel
with the aneurism, it
is sometimes impossible to place a stent graft without blocking the branch
vessel. Such a
condition occurs in approximately 40% of the patients diagnosed with an aortic
aneurism,
wherein the length and diameter of the healthy vessel remaining between the
aneurism and the
branch to the renal arteries, is insufficient to hold a stent graft in place.
In such instances, stent
grafts cannot be used, and certain patients are referred to invasive surgery.
However, surgery is
a relatively high risk procedure, and further, not all patients may be
operated on, thus leaving a
large number of patients with untreated, life threatening, aneurisms.
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[005] There are several published methods aiming at treating such aneurisms;
however, they
all suffer from various disadvantages.
[006] One exemplary such method of treating such aneurisms is the preparation
of a tailored
stent graft, prepared according to the specific anatomy of the patient being
treated. Such a
tailored stent graft is prepared so that it includes openings at the branches,
so as to allow blood
to naturally flow from the main vessel into the side branch vessels. Such
stent grafts are
disclosed, e.g., in U.S. Patent Application Publication No. 2005/0171598.
However, the
preparation of such stent grafts is expensive and is time consuming, since
each needs to be
prepared specifically according to the anatomy of each treated patient.
Further, the placement of
such a tailored stent graft is relatively complicated, and therefore is a
relatively long and high-
risk procedure. Furthermore, such a procedure requires high expertise and is
performed by only
a very limited number of physicians.
[007] Another method for treating such aneurisms is published in U.S. Patent
Application
Publication No. 2009/0240316 ("US `316"), although it is not known to be used
in the art.
According to the disclosure of US `316, a bloused stent-graft is deployed into
a main vessel
such that the bloused section of the bloused stent-graft covers the opening of
a branch vessel
emanating from the main vessel. The bloused section includes loose graft
cloth, and a pressure
differential between the main vessel and the branch vessel causes the bloused
section. to be
forced into an ostium of the branch vessel, thereby creating a pocket aligned
with the branch
vessel. Further, according to US `316, a distal tip of a puncture device is
located in the pocket
and thus aligned with the branch vessel. An outward force is applied to the
puncture device to
cause the distal tip of the puncture device to puncture the bloused section,
thus creating a
collateral opening, or fenestration, in the bloused section precisely aligned
with the branch
vessel. However, it should be understood that the physician placing the stent
graft monitors the
placement thereof by following the blood flow. Therefore, once the bloused
stent graft is
placed, it would be impossible for the physician to see where the branching of
the vessel is,
since the blood flow has stopped. Therefore, it would be impossible, if not
very difficult, to
implement such a method as disclosed in US `316.
[008] U.S. Patent Application Publication No. 2005/0131517 discloses a stent
graft with a
3o relatively flexible or variable fenestration, wherein the fenestration is
placed at the branching
vessel, and a branch vessel stent is placed in the branch vessel. However, it
is questionable
whether such a flexible fenestration would be able to fit the anatomy of any
given patient.
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[009] As known in the art, similar difficulties are encountered when using
stenting
procedures for treating any endovascular conditions involving branching of the
treated blood
vessel. Such endovascular conditions include atherosclerotic vessel stenosis,
iatrogenic stricture
of a vessel, external pressure causing vessel lumen narrowing, aneurismal
dilatation, bleeding
vessel, and any other condition that requires stenting of a bifurcated segment
either by a
dilating stent or a stent graft.
[0010] It would therefore be beneficial to develop a method by which a stent
graft may be used
effectively and efficiently, even in instances where the medical condition
requiring stenting of a
bifurcated segment occurs relatively close to a branching of the vessel.
SUMMARY OF THE INVENTION
[0011 ] As used herein, the term "close proximity of the branching of the main
vessel" is
understood to mean any medical condition requiring stenting of a bifurcated
segment, such
as an aneurism atherosclerotic vessel stenosis, iatrogenic stricture of a
vessel, external
pressure causing vessel lumen narrowing, aneurismal dilatation, bleeding
vessel, that is close
enough to the branching of the main vessel, so that it cannot be treated by
conventional
methods, e.g., using a stent graft, without blocking the blood flow to the
side branch vessel.
According to one embodiment, the medical condition requiring stenting of a
bifurcated
segment is considered to be too close to the branching of the main vessel when
the distance
between the two is approximately 13 mm or less.
[0012] The invention provides a method for forming a fenestration through a
stent graft at a
location where a main vessel in which the stent graft is placed branches into
a side branch
vessel, wherein the method includes:
a. placing a side branch vessel stent in the side branch vessel so that at
least a portion of
the side branch vessel stent protrudes into the lumen of the main vessel; and
b. deploying the stent graft in the main vessel, so that:
i. at least the portion of the side branch vessel stent punctures the stent
graft at the
location where the main vessel branches into the side branch vessel; or
ii. the side branch vessel stent marks the location where the fenestration is
to be
formed, so that additional means may be inserted or may in advance have been
inserted to aid in the creation of the fenestration.
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[0013] The invention further provides a method for treating a medical
condition in a main
vessel that is in close proximity of the branching of the main vessel to a
side branch vessel,
including the following steps:
a) placing a side branch vessel stent in the side branch vessel, so that at
least a portion
of the the branch vessel stent protrudes into the lumen of the main vessel;
and
b) deploying a stent graft in the main vessel,
whereby either:
i) the stent graft is punctured by the side branch vessel stent from the outer
side of the stent graft; or
ii) a puncture point is marked in the stent graft by the side branch vessel
stent
and additional means are used to aid in puncturing the stent graft at the
pucture point.
[0014] The invention additionally provides the use of a side branch vessel
stent to treat a
medical condition in a main vessel that is in close proximity of the branching
of the main
vessel to a side branch vessel, comprising
a) placing a side branch vessel stent in the side branch vessel, so that at
least a portion
of side branch vessel stent protrudes into the lumen of the main vessel; and
b) deploying a stent graft in the main vessel,
whereby either:
i) the stent graft is punctured by the side branch vessel stent from the outer
side of the stent graft; or
ii) a puncture point is marked in the stent graft by the side branch vessel
stent
and additional means are used to aid in puncturing the stent graft at the
pucture point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Embodiments of the invention will be understood and appreciated more
fully from
the following detailed description in conjunction with the figures, which are
not to scale, in
which like reference numerals indicate corresponding, analogous or similar
elements, and in
which:
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[0016] Fig. 1 shows an example of a blood vessel with an aneurism in the
proximity of
branch vessels;
[0017] Fig. 2 shows a side branch vessel fenestration creation device
according to some
embodiments of the invention, in a closed configuration;
[0018] Fig. 3 shows the side branch vessel fenestration creation device,
according to some
embodiments of the invention, in a opened configuration;
[0019] Fig. 4 shows the placement of side branch vessel fenestration creation
device in
branch vessel, according to some embodiments of the invention, in the closed
configuration
so that the side branch vessel fenestration creation device protrudes into the
main vessel
lumen;
[0020] Fig. 5 shows the deployment of the stent graft in the main vessel,
wherein a
fenestration of the stent graft has been created by the side branch vessel
fenestration creation
device at the side branch vessel opening; and
[0021] Fig. 6 shows a cross section of the final configuration of the main
vessel supported
by the stent graft, wherein a fenestration of the stent graft has been created
by the side branch
vessel fenestration creation device, shown in its opened configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0022] In the following detailed description, numerous specific details are
set forth in order to
provide a thorough understanding of the invention. However, it will be
understood by those
skilled in the art that the present invention may be practiced without these
specific details. In
other instances, well-known methods, procedures, and components have not been
described in
detail so as not to obscure the present invention.
[0023] The invention provides a method for creating a fenestration in a stent
graft at the point
where the main vessel, in which the stent graft is placed, branches into a
side branch vessel.
Reference is made to Figure 1 (prior art), which describes an aneurism 20 in a
main vessel 200
that is close to the branching point 10 of the main vessel 200 and the side
branch vessel 100.
[0024] According to this invention, prior to the deployment of the stent graft
in the main
vessel, a side branch vessel fenestration creation device is placed in the
branch vessel so that
the side branch vessel fenestration creation device protrudes into the lumen
of the main vessel.
Once the side branch vessel fenestration creation device is anchored within
the side branch
vessel, the stent graft is deployed in the main vessel. During the deployment,
a fenestration in
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the stent graft is created by the side branch vessel fenestration creation
device, from the outer
side of the stent graft, thereby allowing blood to flow through the stent
graft, through the side
branch vessel fenestration creation device and into the side branch vessel.
According to further
embodiments, once the stent graft is deployed, a fenestration is created at
the branching point of
the vessel using a side branch vessel fenestration creation device and any
additional appropriate
means. According to this embodiment, the side branch vessel fenestration
creation device
marks the point where the fenestration is to be created, so that additional
means may be
inserted, or may in advance be inserted in order to aid in the creation of the
fenestration.
[0025] According to an embodiment of the invention, the side branch vessel
fenestration
creation device has two configurations, the first referred to as the "closed
configuration" and
the second referred to as the "opened configuration". In one embodiment, the
side branch
vessel fenestration creation device is in an open configuration when at rest,
and may be shaped
into a closed configuration for insertion into a branch vessel. As will be
described below, the
side branch vessel fenestration creation device may be "released" from its
closed configuration
into its pre-shaped, open configuration at the appropriate time through the
appropriate means.
[0026] It should be noted that, although the side branch vessel may not be in
need of a stent to
support its structure, as a typical stent would do, and although the side
branch vessel
fenestration creation device may not actually function as a stent within the
side branch vessel to
support its structure, the side branch vessel fenestration creation device may
be referred to-in
the application as a stent, e.g., side branch vessel stent, due to its
placement within the side
branch vessel of the main vessel.
[0027] According to this embodiment, the side branch vessel fenestration
creation device is
placed in the branch vessel in the closed configuration, such that at least a
portion of it
protrudes into the lumen of the main vessel. When the stent graft is deployed
in the main
vessel, a portion of the side branch vessel fenestration creation device in
the closed
configuration punctures the stent graft, thereby enabling the creation of a
fenestration in the
stent graft at the point of branching of the blood vessel, thus allowing blood
to continue its flow
between the main vessel and the side branch vessel. According to further
embodiments, any
appropriate means may be used to puncture the stent graft together with the
side branch vessel
fenestration creation device. According to further embodiments, the side
branch vessel
fenestration creation device marks the point where the fenestration is to be
created, so that
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additional means may be inserted or may in advance be inserted in order to aid
in the creation
of the fenestration.
[0028] According to one embodiment, once a fenestration is formed through the
stent graft at
the branching point of the vessel, the configuration of the side branch vessel
fenestration
creation device is changed to an opened configuration. According to one
embodiment, the
configuration of the side branch vessel fenestration creation device is
changed to the opened
configuration by means of release of a mechanical lock, thus enabling the side
branch vessel
fenestration creation device to obtain a pre=shaped opened configuration.
According to one
embodiment, the side branch vessel fenestration creation device changes its
configuration to the
opened configuration through the application of heat or by any other
appropriate means. The
heat may be applied by a catheter inserted into the vessel, or by any other
appropriate means.
[0029] Reference is now made to Figure 2, which describes one embodiment of
the side
branch vessel fenestration creation device 110 in its closed configuration.
According to this
embodiment, the side branch vessel fenestration creation device 110 includes
two regions,
the side branch vessel fenestration creation device body 111 and the side
branch vessel
fenestration creation device tip 112. According to this embodiment, the side
branch vessel
fenestration creation device body 111 is tubular shaped and is placed in the
side branch
vessel. According to further embodiments, the side branch vessel fenestration
creation device
body 111 is of any other appropriate shape suitable to be placed in the side
branch vessel.
[0030] Additionally, the side branch vessel fenestration creation device body
111 may
include any appropriate means for anchoring the side branch vessel
fenestration creation
device 110 in the side branch vessel (not shown in figure). For example, the
side branch
vessel fenestration creation device body may include struts directed outwardly
that will rest
against the main vessel wall around the branched vessel ostium. According to
one
embodiment, the side branch vessel fenestration creation device 110 is
anchored in the side
branch vessel in the closed configuration, and remains anchored therein also
when changed
to the opened configuration.
[0031 ] The side branch vessel fenestration creation device tip 112 is cone
shaped in the
closed configuration, as shown in Fig. 2. According to other embodiments (not
shown in the
figures), the side branch vessel fenestration creation device tip 112 has the
shape of a
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tetrahedron in the closed configuration when viewed from the end. According to
the
invention, the side branch vessel fenestration creation device tip 112 may be
of any
appropriate shape in the closed configuration that enables the formation of a
fenestration
through the stent graft at the branching point of the blood vessel. According
to one
embodiment, the side branch vessel fenestration creation device tip 112
comprises more than
one finger 113, which form the shape of the closed configuration of the side
branch vessel
fenestration creation device tip, i.e., a cone, tetrahedron, etc. According to
certain
embodiments, the configuration of the fingers 113 is symmetrical, while
according to other
embodiments, it is not.
[0032] Reference is now made to Figure 3, which describes one embodiment of
the opened
configuration of side branch vessel fenestration creation device 110.
According to this
embodiment, the side branch vessel fenestration creation device tip changes
from a cone
shape to a "sun-like" shape composed of several finger-like projections (or
fingers) 113 that
are spread out. According to this embodiment, the fingers 113 serve the
purpose of abutting
the stent graft and the side wall of the main vessel, around the opening of
the side branch
vessel, so that the stent graft and the side wall of the main vessel remain
touching one
another around the fenestration. The number of fingers 113 may be any
appropriate number
in order to fulfill this purpose. According to one embodiment, the number of
fingers is
between three and ten. According to another embodiment, the number of fingers
113 is
between five and nine. According to another embodiment, the number of fingers
113 is
between six and eight. According to another embodiment, the number of fingers
113 is six.
[0033] According to the invention, any other means may also be used for
causing the stent
graft to abut the side wall of the main vessel, around the opening of the side
branch vessel, so
that the stent graft and the side wall of the main vessel remain touching one
another around
the fenestration. According to one embodiment, mechanical force may be applied
from
within the main stent graft so as to ensure that the stent graft and the side
wall of the main
vessel remain touching one another around the fenestration.
[0034] According to the invention, the side branch vessel fenestration
creation device may
be prepared from any appropriate composition, such as nitinol. According to
one
embodiment, the nitinol side branch vessel fenestration creation device is at,
or is close to,
the phase transformation between austenitic and martensitic phases so that it
will be
completely transformed to the austenitic phase when heat (e.g., at a
temperature range of
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approximately 38-45 C) is applied to it. According to further embodiments,
the side branch
vessel fenestration creation device may be formed of nitinol at more than one
transformation
phase. According to certain embodiments, the side branch vessel fenestration
creation device
body 111 is made of nitinol at the fully austenitic phase, while the side
branch vessel
fenestration creation device tip 112 is made of nitinol at a different
metallurgic phase, such
as the martensitic phase. According to further embodiments, the side branch
vessel
fenestration creation device tip 112 is set at a metallurgic phase that is not
fully martensitic
and not fully austenitic.
[0035] As shown in Figure 4, the side branch vessel fenestration creation
device 110 is
placed in the side branch vessel 100 and set therein in such a way that the
side branch vessel
fenestration creation device tip 112 in its closed configuration protrudes
into the lumen of
the main vessel 200. Then, as depicted in Figure 5, once the stent graft 210
is deployed in the
main vessel 200, the tip 112 of the side branch vessel fenestration creation
device 110
protrudes into and creates a fenestration in the wall of the stent graft 210.
Subsequently, as
described in Figure 6, the side branch vessel fenestration creation device 110
is further
transformed into its opened configuration, thus spreading fingers 113 and
anchoring the stent
graft 210 to the side wall of the main vessel 200, around the opening of the
side branch
vessel 100.
[0036] The invention further includes a method for treating a medical
condition in a main
vessel that is in close proximity of the branching of the main vessel,
including the following
steps:
a) placing a side branch vessel fenestration creation device in the side
branch
vessel, so that an end thereof protrudes into the lumen of the main vessel;
and
b) deploying a stent graft in the main vessel,
whereby the end of the side branch vessel fenestration creation device
protrudes into and
punctures the stent graft from the outer side of the stent graft, thereby
creating a fenestration
therethrough.
[0037] According to further embodiments, once the stent graft is deployed, a
fenestration is
created at the branching point of the vessel using the side branch vessel
fenestration creation
3o device and any additional appropriate means. According to further
embodiments, the side
branch vessel fenestration creation device marks the point where the
fenestration is to be
created, so that additional means may be inserted to aid in the creation of
the fenestration.
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[0038] According to some embodiments of the invention, the method of this
invention
further includes means of anchoring the side branch vessel fenestration
creation device in the
side branch vessel. According to further embodiments, the method of this
invention further
includes means of causing the stent graft to abut the side wall of the main
vessel around the
opening of the side branch vessel, so that the stent graft and the side wall
of the main vessel
remain touching one another around the fenestration.
[0039] This invention further includes the use of a side branch vessel
fenestration creation
device to treat a medical condition in a main vessel that is in close
proximity of the
branching of the main vessel, comprising
a) placing a side branch vessel fenestration creation device in the side
branch
vessel, so that an end thereof protrudes into the lumen of the main vessel;
and
b) deploying a stent graft in the main vessel,
whereby the end of the side branch vessel fenestration creation device
protrudes into a
punctures the stent graft from the outer side of the stent graft, thereby
creating a fenestration
therethrough.
[0040] According to further embodiments, once the stent graft is deployed, a
fenestration is
created at the branching point of the vessel using the side branch vessel
fenestration creation
device and any additional appropriate means. According to further embodiments,
the side
branch vessel fenestration creation device marks the point where the
fenestration is to be
created, so that additional means may be inserted to aid in the creation of
the fenestration.
[0041 ] According to some embodiments, the use of a side branch vessel
fenestration creation
device to treat an aneurism that is in close proximity of the branching of the
main vessel
further includes means of anchoring the side branch vessel fenestration
creation device in the
side branch vessel. According to further embodiments, the use of a side branch
vessel
fenestration creation device to treat an aneurism that is in close proximity
of the branching of
the main vessel further includes means of causing the stent graft to abut the
side wall of the
main vessel around the opening of the side branch vessel, so that the stent
graft and the side
wall of the main vessel remain touching one another around the fenestration.
[0042] Various aspects of the invention are described in greater detail in the
following
3o Examples, which represent embodiments of this invention, and are by no
means to be
interpreted as limiting the scope of this invention.
