Note: Descriptions are shown in the official language in which they were submitted.
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695
-1-
BIFURCATED STENT DELIVERY SYSTEM AND METHOD OF USE
TECHNICAL FIELD
In one of its aspects, the present invention relates to an endovascular
sleeve for use in delivery of a bifurcated stent. In another of its aspects,
the
present invention relates to bifurcated stent delivery kit. In yet another of
its
aspects, the present invention relates to a method for delivery of a
bifurcated
stent.
BACKGROUND ART
Stents are generally known. Indeed, the term "stent" has been used
interchangeably with terms such as "intraluminal vascular graft" and
"expansible
prosthesis". As used throughout this specification, the term "stent" is
intended
to have a broad meaning and encompasses any expandable prosthetic device for
implantation in a body passageway (e.g., a lumen or artery).
In the past ten years, the use of stents has attracted an increasing amount
of attention due the potential of these devices to be used, in certain cases,
as an
alternative to surgery. Generally, a stent is used to obtain and maintain the
patency of the body passageway while maintaining the integrity of the
passageway. As used in this specification, the term "body passageway" is
intended to have a broad meaning and encompasses any duct (e.g., natural or
iatrogenic) within the human body and can include a member selected from the
group comprising: blood vessels, respiratory ducts, gastrointestinal ducts and
the
like.
Stent development has evolved to the point where the vast majority of
currently available stents rely on controlled plastic deformation of the
entire
structure of the stent at the target body passageway so that only sufficient
force
to maintain the patency of the body passageway is applied during expansion of
the stent.
Generally, in many of these systems, a stent, in association with a balloon,
is delivered to the target area of the body passageway by a catheter system.
Once
the stent has been properly located (for example, for intravascular
implantation
CA 02339133 2004-01-30
WO 00/07523 PCT/CA99/00695
-2-
the target area of the vessel can be filled with a contrast medium to
facilitate
visualization during fluoroscopy), the balloon is expanded thereby plastically
deforming the entire structure of the stent so that the latter is urged in
place
against the body passageway. As indicated above, the amount of force applied
is at least that necessary to expand the stent (i.e., the applied the force
exceeds the minimum force.above which the stent material will undergo plastic
deformation)
while maintaining the patency of the body passageway. At this point, the
balloon
is deflated and withdrawn within the catheter, and is subsequently removed.
Ideally, the stent will remain in place and maintain the target area' of the
body
passageway substantially free of blockage (or narrowing).
See, for example, any of the following patents:
United States patent 4,733,665 (Pahnaz),
United States patent 4,739,762 (Palmaz),
United States patent 4,800,882 (Gianturco),
United States patent 4,907,336 (Gianturco),
United States patent 5,035,706 (Gianturco et al.),
United States patent 5,037,392 (Hillstead),
United States patent 5,041,126 (Gianturco),
United States patent 5,102,417 (Palmaz),
United States patent 5,147,385 (Beck et al.),
United States patent 5,282,824 (Gianturco),
United States patent 5,316,023 (Palmaz et al.),
Canadian patent 1,239,755 (Wallsten),
Canadian patent 1,245,527 (Gianturco et al.),
Canadian patent application number 2,171,047 (Penn et al.),
Canadian patent application number 2,175,722 (Penn et al.),
Canadian patent application number 2,185,740 (Penn et al.),
Canadian patent application number 2,192,520 (Penn et al.),
International publication no. WO 97/32543 (Penn et al.), and
International publication no. WO 97/32544 (Penn et al.),
CA 02339133 2004-01-30
WO 00/07523 PCT/CA99/00695
-3-
for a
discussion on previous stent designs and deployment systems.
All of the stents described in the above-identified patents share the
common design of being mono-tubular and thus, are best suited to be delivered
and implanted in-line in the body passageway. These known stents are
inappropriate for use in a bifurcated body passageway (e.g., a body passageway
comprising a parent passageway that splits into a pair of passageways).
Further,
these stents are inappropriate for use in a body passageway having side
branches
since: (i) inaccurate placement of the stent substantially increases the risk
to the
patient, (ii) the risk of passageway closure in the side branches is
increased, and
(iii) the side branches will be substantially inaccessible.
Indeed, the Physician Guide published in support of the Palmaz-Schatz
stent states on page 32:
"... no attempt should be made following placement of a
PALMAZ-SCHATZ stent to access the side branch with a guide
wire or a balloon, as such attempts may result in additional
damage to the target vessel or the stent. Attempts to treat
obstructed side branches within stented segments can result in
balloon entrapment, necessitating emergency bypass surgery."
Thus, when installed, the Palmaz-Schatz stent admittedly shields side branches
emanating from the target area of the body passageway effectively permanently.
This can be problematic since the only way to treat blockage or other problems
associated with the side branches is to perform the type of surgery which
installation of the stent was intended to avoid.
This contraindication for conventional mono-tubular stents is corroborated
by a number of investigators. See, for example, the following:
1. Interventional Cardiovascular Medicine: Principles and
Practice (1994); Publisher: Churchill Livingstone Inc.;
CA 02339133 2004-01-30
WO 00/07523 PCT/CA99/00695 -
-4-
pages 221-223 (Ohman et al.), 487-488 (Labinaz et al.),
667-668 (Bashore et al.) and 897 (Bailey et al.), including
references cited therein; .
2. Gianturco-Roubin Flex-StentTM Coronary Stent:
Physician's Guide; page 2, Paragraph 3 under
WARNINGS;
3. Circulation, Vol. 83, No. 1, January 1991 (Schatz et al.);
entitled "Clinical Experience With the Paimaz-Schatz
Coronary Stent"; pages 148-161 at page 149; and
4. American Heart Journal, Vol. 127, No. 2, February 1994
(Eeckhout et al.); entitled "Complications and follow-up
after intracoronary stenting: Critical analysis of a 6-year
single-center experience"; pages 262-272 at page 263.
Further, some investigators have attempted to install individual stents in
each branch of the bifurcated body passageway. However, this approach is
fraught with at least two significant problems. First, implantation of three
individual stents is technically challenging and, together with the expansive
forces generated upon implantation, results in subjecting the central walls of
the
bifurcated body passageway to undue stress and trauma which may lead to post-
procedural complications. Second, since the central walls (i.e., in the crotch
area)
of the bifurcated body passageway are not supported by the individual stents,
this
area of the passageway is left substantially unprotected and susceptible to
blockage.
One particular problem area with bifurcated body passageways is the
occurrence of bifurcation lesions within the coronary circulation. Generally,
these legions may be classified as follows:
CA 02339133 2004-01-30
WO 00/07523 PCT/CA99/00695
-5-
Type Characteristic
A Prebranch stenosis not involving the ostium of the
side branch;
B Postbranch stenosis of the parent vessel not
involving the origin of the side branch;
C Stenosis encompassing the side branch but not
involving the ostium;
D Stenosis involving the parent vessel and ostium of
the side branch;
E Stenosis involving the ostium of the side branch
only; and
F Stenosis discretely involving the parent vessel and
ostium of the side branch.
See Atlas of Interventional Cardiolog), (Popma et al.), 1994, pages 77-79.
The presence of
bifurcation lesions is predictive of increased procedural complications
including
acute vessel closure.
United States patent 4,994,071 (MacGregor),
discloses a bifurcating stent apparatus. The
particular design incorporates a series of generally parallel oriented loops
interconnected by a sequence of "half-birch" connections. The lattice
structure
of the illustrated stent is constructed of wire. The use of such wire is
important
to obtain the loop structure of the illustrated design. United States patents
3,993,078 (Bergentz et al.) and 5,342,387 (Summers),
CA 02339133 2004-01-30
WO 00/07523 PCT/CA99/00695
-6-
also disclose and illustrate a
bifurcated stent design constructed of wire.
In published Canadian patent application number 2,134,997 (Penn et al.)
and published International publication no. WO 97/41803 (Penn et al.), we
describe
various novel bifurcated stents.
Thus, while bifurcated stents are generally known, the base of knowledge
relating thereto is significantly less than that relating to monotubular
stents. Not
surprisingly there is a similar imbalance of knowledge relating t6 the
delivery
systems for such stents. Specifically, there is vast knowledge relating
delivery
systems for monotubular stents compared to the knowledge that exists for
bifurcated stent delivery systems.
In the delivery of any stent (monotubular or bifurcated) it is reasonably
well accepted that the stent is mounted on a catheter which is navigated over
a
guidewire previously inserted through a guide catheter to the target location.
Thus, when the object is to deliver a bifurcated stent, it is envisaged that a
pair
of guidewires would be used - i.e., one for each of the two passageways that
branch off the primary passageway. As such, it is important that, in the
primary
passage, the guidewires do not become entangled, either in the guide catheter
or
the body passageway, as this will prevent navigation of the catheter to the
target
location. In addition, the limited size of the guide catheter determines the
bulkiness of the bifurcated stent delivery system. The practical result of
this is
that the current approach of delivering bifurcated stents is bulky, cumbersome
and technically challenging. To date, the present inventors are unaware of a
solution to the problems of conventional bifurcated stent delivery.
Accordingly, it would be desirable to have a system which could be used
to navigate a pair of guidewires in a substantially untangled manner to
facilitate
delivery of the bifurcated stent. It would be further advantageous is such a
system were relatively miniaturized compared to conventional bifurcated stent
delivery systems.
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695 -
-7-
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a novel bifurcated stent
delivery system which obviates or mitigates at least one of the above-
mentioned
disadvantages of the prior art.
Thus, in one of its aspects, the present invention provides an endovascular
sleeve for delivering a pair of guidewires to a bifurcated body passageway,
the
sleeve comprising a first tubular passageway and a second tubular passageway
fixed with respect to one another, the first tubular passageway comprising a
first
distal end and a first proximal end, the second tubular passageway comprising
a
second distal end and a second proximal end, the first distal end being longer
than
the second distal end to define a junction which abuts against a crotch in the
bifurcated body passageway.
A bifurcated stent delivery kit for delivery of a bifurcated stent to a
bifurcated body passageway, the kit comprising:
a catheter;
a pair of guidewires; and
an endovascular sleeve for delivering the guidewires to a bifurcated body
passageway, the sleeve comprising a first tubular passageway and a second
tubular passageway fixed with respect to one another, the first tubular
passageway comprising a first distal end and a first proximal end, the second
tubular passageway comprising a second distal end and a second proximal end,
the first distal end being longer than the second distal end to define a
junction
which abuts against a crotch in the bifurcated body passageway.
In yet another of its aspects, the present invention provides method for
delivery of a bifurcated stent to a target bifurcated body passageway having a
proximal body passageway, a first distal body passageway and a second distal
body passageway using an endovascular sleeve comprising a first tubular
passageway and a second tubular passageway fixed with respect to one another,
the first tubular passageway comprising a first distal end and a first
proximal end,
the second tubular passageway comprising a second distal end and a second
proximal end, the first distal end being longer than the second distal end to
define
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695
-8-
a junction which abuts against a crotch in the bifurcated body passageway, the
method comprising the steps of:
(i) navigating a first guidewire through the primary proximal body
passageway and into the first distal body passageway;
(ii) feeding the first tubular passageway of the endovascular sleeve
over the first guidewire;
(iii) navigating the endovascular sleeve through the primary proximal
body passageway until the first distal end is disposed in the first distal
body
passageway and the junction abuts a crotch in the bifurcated body passageway;
(iv) navigating a second guidewire through the second tubular
passageway and into the second distal body passageway;
(v) withdrawing the endovascular sleeve from the body passageway;
(vi) guiding a catheter over the first guidewire and the second
guidewire, the catheter having a bifurcated stent disposed thereon;
(vii) navigating the bifurcated stent to the target bifurcated body
passageway; and
(viii) expanding the bifurcated stent.
Thus, the present inventors have developed an endovascular sleeve which
can be utilized to navigate a pair of guidewires to a bifurcated body
passageway
such that, once in place, the guidewires are substantially untwisted or
untangle.
This greatly facilitates delivery of the bifurcated stent to the bifurcated
artery.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will be described with reference to
the accompanying drawings wherein like numerals designate like parts and in
which:
Figure 1 illustrates a side elevation of a first embodiment of the present
endovascular sleeve;
Figure 2 illustrates a side elevation of a second embodiment of the present
endovascular sleeve;
Figures 3-7 illustrate enlarged views of how the present endovascular
sleeve may be used to deliver a pair of guidewires;
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695
-9-
Figures 8-12 illustrate perspective views of how the present endovascular
sleeve may be used to deliver a pair of guidewires;
Figures 13-15 illustrate enlarged view of how a bifurcated stent may be
delivered once the pair of guidewires are in place; and
Figure 16 illustrates an enlarged view of the implanted bifurcated stent
delivered in Figures 13-15.
BEST MODE FOR CARRYING OUT THE INVENTION
With reference to Figure 1, there is shown an endovascular sleeve 10.
Endovascular sleeve 10 comprises a first tubular passageway 20 having a first
distal end 22 and first proximal end 24. Endovascular sleeve 10 further
comprises a second tubular passageway 30 having a second distal end 32 and
second proximal end 34. First tubular passageway 20 and second tubular
passageway 30 are joined and fixed with respect to one another along a seam
40.
As illustrated, first distal end 22 extends beyond second distal end 32. This
offset
between first distal end 22 and second distal end 32 defines a junction 45
Preferably, first distal end 22 extends beyond second distal end 32 by a
margin
of at least about 0.3 cm, more preferably by a margin in the range of from
about
0.3 cm to about 3 cm, most preferably by a margin in the range of from about
0.5
cm to about 2 cm. Further, first proximal end 24 is significantly offset with
respect to second proximal end 34. As will be developed below, this offset
renders endovascular sleeve 10 as a "over-the-wire/monorail" delivery system.
As shown, each of first distal end 22 and second distal end 32 are chamfered
or
bevelled.
With reference to Figure 2, there is shown an endovascular sleeve 100.
Endovascular sleeve 100 comprises a first tubular passageway 120 having a
first
distal end 122 and first proximal end 124. Endovascular sleeve 100 further
comprises a second tubular passageway 130 having a second distal end 132 and
second proximal end 134. First tubular passageway 120 and second tubular
passageway 130 are joined and fixed with respect to one another along a seam
140. As illustrated, first distal end 122 extends beyond second distal end
132.
This offset between first distal end 122 and second distal end 132 defines a
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695 -
-10-
junction 145. Preferably, first distal end 122 extends beyond second distal
end
132 by a margin of at least about 0.3 cm, more preferably by a margin in the
range of from about 0.3 cm to about 3 cm, most preferably by a margin in the
range of from about 0.5 cm to about 2 cm. Further, unlike in the "over-the-
wire/monorail" delivery system illustrated in Figure 1, first proximal end 124
is
substantially even with respect to second proximal end 134. This relatively
even
disposition of first proximal end 124 and second proximal end 134 renders
endovascular sleeve 100 as a "double over-the-wire" delivery system. As shown,
each of first distal end 122 and second distal end 132 are chamfered or
bevelled.
The material used to constructed endovascular sleeve 10 is not particularly
restricted provided of course that it: (i) sufficient integrity to by
navigated
through tortuous body passageways, and (ii) is non-toxic to the subject in
which
endovascular sleeve 10 is being navigated. Non-limiting examples of suitable
materials include bioplastic polymers, a flexible metal tube and the like.
With reference to Figures 3-7, the use of endovascular sleeve 10 used to
deliver a pair of guidewires will be discussed.
As shown, a bifurcated body passageway 50 comprises a proximal
passageway 52 and a pair of distal passageways 54,56. The junction of distal
passageways 54,56 defines a crotch 58. For clarity, the stenosis of bifurcated
body passageway 50 is not illustrated.
With reference to Figure 3, a first guidewire 60 is navigated through
proximal passageway 52 and into distal passageway 54 in the direction of arrow
A.
With reference to Figure 4, first tubular passageway 20 is fed over
guidewire 60 in the direction of arrow A and navigated until it enters distal
passageway 54 and junction 40 of endovascular sleeve 10 abuts crotch 58 of
bifurcated body passageway 50. In the illustrated embodiment, endovascular
sleeve 10 is provided with a radioopaque marker (e.g., made of gold and the
like)
near or at junction 40 so that the position ofjunction 40 relative to crotch
58 can
be monitored using conventional image radiography techniques. Once
endovascular sleeve 10 is positioned in this fashion, second distal end 32 of
second tubular passageway 30 opens into distal passageway 56.
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695
-11-
With reference to Figure 5, once endovascular sleeve 10 is in place (i.e.,
as shown in Figure 4), a second guidewire 62 is fed through second tubular
passageway 30 into distal passageway 56 in the direction of arrow A.
With reference to Figure 6, once guidewires 60,62 are positioned
correctly, endovascular sleeve 10 is withdrawn from bifurcated body passageway
50 in the direction of arrow B. As will be apparent to those of skill in the
art, care
should be taken to avoid twisting of endovascular sleeve 10 since this could
result
in conveyance of the twist to guidewires 60,62.
With reference to Figure 7, once endovascular sleeve 10 is completely
withdrawn from bifurcated body passageway 50, guidewires 60,62 remain with
the distal ends thereof in distal passageways 54,56, respectively.
With reference to Figures 8-12, there are illustrated perspective views of
the use of endovascular sleeve 10 to deliver a pair of guidewires as described
hereinabove with respect to Figures 3-7.
As illustrated, endovascular sleeve 10 is introduced to a subject 70 via a
suitable incision near the groin of subject 70. Generally speaking, the
concordance of the perspectives view illustrated in Figures 8-12 to the
enlarged
view illustrated in Figures 3-7 is as follows:
Figure 8 concords with Figure 3;
Figures 9 and 10 concord with Figure 4;
Figure 11 concords with Figure 5; and
Figure 12 concords with Figures 6 and 7.
As discussed above, endovascular sleeve 10 may be regarded as an "over-
the-wire/monorail" delivery system. By this it is meant that, once the sleeve
is
in the correct position, one tubular passageway (30) remains over a guidewire
(62) such that the proximal end thereof (34) emanates from the subject whereas
the proximal end (24) of the other tubular passageway (20) does not emanate
from the subj ect. In other words, the section of the other tubular passageway
(20)
between the bifurcated body passageway (50) and incision (72) in the subject
(70)
does not completely cover the other guidewire (60).
CA 02339133 2001-01-31
WO 00/07523 PCT/CA99/00695
-12-
As discussed above, endovascular sleeve 100 may be regarded as a
"double over-the-wire" delivery system. By this is meant that, once the sleeve
is in the correct position, both tubular passage ways (120,130) remain over
their
respective guidewires (60,62) such that the proximal end (24) of each tubular
passageway (120,130) emanates from the subject. In other words, both
guidewires (60,62) are substantially completely covered by endovascular sleeve
100.
With reference to Figure 7, once the endovascular sleeve is removed,
guidewires 60,62 remain as illustrated and are substantially untwisted to the
point
at which they emanate from the subject. With reference to Figure 13, at this
point, a catheter 80 is used to deliver a bifurcated stent to bifurcated body
passageway 50. Specifically, catheter 80 comprises a balloon 82 having a pair
of tubes 84,86 emanating from one end thereof. Mounted on balloon 82 is a
bifurcated stent 88. Tubes 84,86 are of a conventional, annular design such
that
they can be disposed over their respective guidewires and can receive a fluid
which is used to fill balloon 82 resulting in expansion thereof. Thus,
catheter 80
is navigated over guidewires 60,62 until the bifurcated stent is in the
correct
position - see Figure 14. At this point, a pressurized fluid (e.g., saline) is
introduced into balloon 82 via tubes 84,86 resulting in expansion of balloon
82
and stent 88 - see Figure 15. Thereafter, balloon 82 is deflated
conventionally
and withdrawn from bifurcated body passage way 50 leaving stent 88 in a
deployed state - see Figure 16. While balloon 82 is shown as a pair of
adjacent
single balloons, those of skill in the art will appreciate that a bifurcated
balloon
could be used in place of a pair of single balloons.
While this invention has been described with reference to illustrative
embodiments, this description is not intended to be construed in a limiting
sense.
Various modifications of the illustrative embodiments, as well as other
embodiments of the invention, will be apparent to persons skilled in the art
upon
reference to this description. It is therefore contemplated that the appended
claims will cover any such modifications or embodiments.
