U.S. patent application number 13/099095 was filed with the patent office on 2011-08-25 for catheter assembly and method for treating bifurcations.
This patent application is currently assigned to ABBOTT CARDIOVASCULAR SYSTEMS INC.. Invention is credited to Kenneth Kay Armstrong, Leonardo D. Barbod, Daniel L. Cox, Jessie Delgado, Thomas Ray Hatten, Brenna K. Hearn, Darrin J. Kent, Stephen Dirk Pacetti, Diem Uyen Ta, David K. Wrolstad, Caroline Wu.
Application Number | 20110208286 13/099095 |
Document ID | / |
Family ID | 38670565 |
Filed Date | 2011-08-25 |
United States Patent
Application |
20110208286 |
Kind Code |
A1 |
Ta; Diem Uyen ; et
al. |
August 25, 2011 |
CATHETER ASSEMBLY AND METHOD FOR TREATING BIFURCATIONS
Abstract
An improved stent design and stent delivery catheter assembly
for repairing a main vessel and a side branch vessel forming a
bifurcation. The stent includes rings aligned along a common
longitudinal axis and connected by links, where the stent has one
or more portals for aligning with and partially expanding into the
opening to the side branch vessel. The stent is implanted at a
bifurcation so that the main stent section is in the main vessel,
and the portal section covers at least a portion of the opening to
the side branch vessel. A second stent can be implanted in the side
branch vessel and abut the expanded central section to provide full
coverage of the bifurcated area in the main vessel and the side
branch vessel. Radiopaque markers on the stent and on the tip of
the delivery catheter assist in aligning the portal section with
the opening to the side branch vessel.
Inventors: |
Ta; Diem Uyen; (San Jose,
CA) ; Wu; Caroline; (San Jose, CA) ; Hearn;
Brenna K.; (San Francisco, CA) ; Cox; Daniel L.;
(Palo Alto, CA) ; Barbod; Leonardo D.; (San Diego,
CA) ; Delgado; Jessie; (Murrieta, CA) ;
Pacetti; Stephen Dirk; (San Jose, CA) ; Hatten;
Thomas Ray; (Los Altos, CA) ; Wrolstad; David K.;
(Temecula, CA) ; Armstrong; Kenneth Kay;
(Riverside, CA) ; Kent; Darrin J.; (Murrieta,
CA) |
Assignee: |
ABBOTT CARDIOVASCULAR SYSTEMS
INC.
Santa Clara
CA
|
Family ID: |
38670565 |
Appl. No.: |
13/099095 |
Filed: |
May 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11643208 |
Dec 21, 2006 |
7959667 |
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13099095 |
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11483300 |
Jul 7, 2006 |
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11643208 |
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Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61F 2/958 20130101;
A61F 2/954 20130101; A61F 2250/006 20130101; A61F 2/91 20130101;
A61F 2002/067 20130101; A61F 2002/91525 20130101; A61F 2002/91575
20130101; A61F 2/856 20130101; A61F 2/915 20130101 |
Class at
Publication: |
623/1.11 |
International
Class: |
A61F 2/84 20060101
A61F002/84 |
Claims
1-83. (canceled)
84. A stent delivery balloon catheter, comprising: a) an elongated
shaft, having i) a proximal section having a first inflation lumen;
ii) a bifurcated distal section having a first branch with a second
inflation lumen within at least a portion thereof, and a second
branch with a third inflation lumen within at least a portion
thereof, the second and third inflation lumens each being in fluid
communication with the first inflation lumen, the bifurcated distal
section further having a secured portion along which the first and
second branches are permanently secured together, and an unsecured
portion proximally adjacent to the secured portion and along which
the first and second branches are not secured together; iii) an
intermediate section joining the proximal and distal sections
together, and having a fourth inflation lumen in fluid
communication with the first, second, and third inflation lumens;
and iv) a joining wire lumen extending within the proximal section,
the intermediate section, and the first branch, and a guidewire
lumen extending within at least the intermediate section and the
second branch; and b) a first balloon on the first branch having an
inflatable interior in fluid communication with the second
inflation lumen, and a second balloon on the second branch having
an inflatable interior in fluid communication with the third
inflation lumen, and the inflatable interior of the first balloon
and the inflatable interior of the second balloon are located
distal to the secured portion of the bifurcated distal section; c)
a coupler secured to the second branch, located distal to the
inflatable interior of the second balloon, and configured for
releasably coupling the first and second branches together to form
a coupled configuration; and d) a stent releaseably mounted on the
first and second balloons, located distal to the secured portion of
the distal shaft section.
85. The catheter of claim 84, wherein the secured portion is formed
at least in part by a tubular outer band member which constrains
the first and second branches of the distal shaft section
together.
86. The catheter of claim 85, wherein the tubular outer band member
is adhesively bonded to the first and second branches.
87. The catheter of claim 84, wherein the secured portion is a
first secured portion located approximately midway between a
proximal end of one or both of the first and second balloons and a
proximal end of the branched distal shaft section.
88. The catheter of claim 87, including a second secured portion at
adjacent to and proximally spaced apart from the proximal end of
one or both of the first and second balloons, such that the second
secured portion is distally spaced apart from the first secured
portion by an unsecured portion of the first and second branches of
the distal shaft section.
89. The catheter of claim 84, wherein the secured portion is formed
at least in part by a tubular outer band member of heat shrink
tubing, heat shrunk around the first and second branches, and
conforming to the underlying outer surfaces of the secured first
and second branches such that the tubular outer band member has an
hourglass shape.
90. The catheter of claim 84, wherein the first branch includes a
soft distal tip member forming the distal end of the first branch,
and having the joining wire lumen therein and a radiopaque distal
tip marker surrounding a distal end section of the joining wire
lumen, located distal to the inflatable interior of the first
balloon, wherein the radiopaque tip marker is an annular ring
surrounding and secured to an outer surface of at least a section
of the soft distal tip member.
91. The catheter of claim 90, including a nonradiopaque outer
sheath surrounding the proximal end of the soft distal tip member
and wherein the radiopaque tip marker has an inner surface secured
to an outer surface of the outer sheath, and has a proximal end
located distal to the distal end of the nonradiopaque sleeve, and a
distal end located proximal to the distal end of the soft distal
tip member.
92. The catheter of claim 84, further comprising a radiopaque
distal tip marker surrounding a distal end section of the joining
wire lumen, located distal to the inflatable interior of the first
balloon, wherein the radiopaque distal tip marker is a soft distal
tip member forming the distal end of the first branch, and having
the joining wire lumen therein.
93. The catheter of claim 84, further comprising a radiopaque
distal tip marker surrounding a distal end section of the joining
wire lumen, located distal to the inflatable interior of the first
balloon, wherein the radiopaque distal tip marker is located distal
to a distal end of the first balloon.
94. The catheter of claim 93, including one or more balloon
radiopaque metal markers on the catheter distal shaft section
within the inflatable interiors of the balloon, of a different
composition than the radiopaque distal tip marker.
95. The catheter of claim 94, wherein the radiopaque distal tip
marker is longer than the radiopaque balloon markers.
96. A balloon catheter, comprising: a) an elongated catheter shaft
having a branched distal section with a first and a second branch
configured for releasably coupling together to form a coupled
configuration, an inflation lumen, and a joining wire lumen
extending at least within the first branch of the branched distal
section; and b) a first balloon on the first branch with an
inflatable interior in fluid communication with the inflation
lumen, and a second balloon on the second branch with an inflatable
interior in fluid communication with the inflation lumen.
97. The catheter of claim 96, including a stent releaseably mounted
on at least one of the first and second.
98. The catheter of claim 96, wherein the first branch has at least
one secured portion along which the first branch is permanently
secured to the second branch at a location spaced between a
proximal end of the branched distal shaft section and a proximal
end of the inflatable interiors of the first and second
balloons.
99. The catheter of claim 96, including a joining guidewire
disposed within the joining wire lumen, and within a guidewire
locking mechanism located proximal to the catheter shaft, having a
locked mode in which the catheter is releasably locked to the
guidewire disposed within the joining wire lumen, and an unlocked
mode in which the joining guidewire is slidably disposed within the
joining wire lumen.
100. The catheter of claim 99, including a proximal adapter secured
to a proximal end of the catheter shaft, having a port configured
for connecting to a source of inflation fluid for inflating the
first and second balloons, and the guidewire locking mechanism
comprises a proximal fitting which is connected to the proximal
adapter and which tightens onto the proximal adapter to place the
guidewire locking mechanism in the locked mode.
101. The catheter of claim 100, wherein the guidewire locking
mechanism comprises a radially collapsible slotted head of a collet
member or of an inner extension of the proximal fitting, the
slotted head being positioned within the proximal adapter when the
proximal fitting is connected to the proximal adapter.
102. The catheter of claim 99, including a proximal adapter secured
to a proximal end of the catheter shaft, having a port configured
for connecting to a source of inflation fluid for inflating the
first and second balloons, wherein the guidewire locking mechanism
comprises a guidewire locking torque handle which reversibly
engages the joining guidewire to provide a finger hold for
manipulating the joining guidewire, and which, in the locked mode,
is releaseably connected to a proximal fitting at a proximal end of
the proximal adapter.
103. The catheter of claim 96, wherein the second branch has a
fixed guidewire with a distal section permanently secured to a
distal end section of the second branch, such that a section of the
fixed guidewire located proximal to the second balloon extends
directly within the inflation lumen of the second branch and not
within a guidewire lumen of the catheter shaft.
Description
[0001] This application is a divisional of currently pending Ser.
No. 11/643,208, filed Dec. 27, 2006; which is a continuation of
U.S. Ser. No. 11/483,300, filed Jul. 7, 2006.
BACKGROUND OF THE INVENTION
[0002] The invention relates to stents and stent delivery and
deployment assemblies for use at a bifurcation and, more
particularly, one or more stents for repairing bifurcations, blood
vessels that are diseased, and a method and apparatus for delivery
and implantation of the stents.
[0003] Stents conventionally repair blood vessels that are
diseased. Stents are generally hollow and cylindrical in shape and
have terminal ends that are generally perpendicular to their
longitudinal axis. In use, the conventional stent is positioned at
the diseased area of a vessel and, after deployment, the stent
provides an unobstructed pathway for blood flow.
[0004] Repair of vessels that are diseased at a bifurcation is
particularly challenging since the stent must be precisely
positioned, provide adequate coverage of the disease, provide
access to any diseased area located distally to the bifurcation,
and maintain vessel patency in order to allow adequate blood flow
to reach the myocardium. Therefore, the stent must provide adequate
coverage to the diseased portion of the bifurcated vessel, without
compromising blood flow, and extend to a point within and beyond
the diseased portion. Where the stent provides coverage to the
vessel at the diseased portion, yet extends into the vessel lumen
at the bifurcation, the diseased area is treated, but blood flow
may be compromised in other portions of the bifurcation. Unapposed
stent elements may promote lumen compromise during neointimal
formation and healing, producing restenosis and requiring further
procedures. Moreover, by extending into the vessel lumen at the
bifurcation, the stent may block access to further interventional
procedures.
[0005] Conventional stents are designed to repair areas of blood
vessels that are removed from bifurcations and, therefore, are
associated with a variety of problems when attempting to use them
to treat lesions at a bifurcation. Conventional stents are normally
deployed so that the entire stent is either in the parent vessel or
the proximal portion of the stent is in the parent vessel and the
distal portion is located in the side branch vessel. In both cases,
either the side branch vessel (former case) or the parent vessel
(later case), would become "jailed" by the stent struts. This
technique repairs one vessel at the bifurcation at the expense of
jailing or obstructing the alternate vessel.
[0006] Blood flow into the jailed vessel would be compromised as
well as future access and treatment into the distal portion of the
jailed vessel.
[0007] Alternatively, access into a jailed vessel can be attained
by carefully placing a guide wire through the stent and
subsequently tracking a balloon catheter through the stent struts.
The balloon could then be expanded, thereby deforming the stent
struts and forming an opening into the previously jailed vessel.
The cell to be spread apart is currently randomly and blindly
selected by crossing the deployed stent with a guide wire. The
drawback with this approach is that there is no way to determine or
guarantee that the main-vessel stent struts are properly oriented
with respect to the side branch or that an appropriate stent cell
has been selected by the wire for dilatation. The aperture created
often does not provide a clear opening and creates a major
distortion in the surrounding stent struts. A further drawback with
this approach is that it is difficult to determine if the stent
struts in the stented vessel have been properly oriented and spread
apart to provide a clear opening for stenting the jailed vessel.
This technique also causes stent deformation to occur in the area
adjacent to the carina, pulling the stent away from the vessel wall
and partially obstructing flow in the originally non-jailed vessel.
Deforming the stent struts to regain access into the previously
jailed vessel is also a complicated and time consuming procedure
associated with attendant risks to the patient and is typically
performed only if considered an absolute necessity. Vessels which
supply a considerable amount of blood to the myocardium and may be
responsible for the onset of angina or a myocardial infarct typify
what would necessitate the subsequent strut deformation in order to
reestablish blood flow into the vessel. The risks of procedural
complications during this subsequent deformation are considerably
higher than stenting in normal vessels. The inability to place a
guide wire through the jailed lumen in a timely fashion could
restrict blood supply and begin to precipitate symptoms of angina
or even cardiac arrest. In addition, disturbed hemodynamics and
subsequent thrombus formation at the jailed site could further
compromise blood flow into the side branch.
[0008] Plaque shift is also a phenomena which is of concern when
deploying a stent across a bifurcation. Plaque shift occurs when
treatment of disease or plaque in one vessel causes the plaque to
shift into another location. This is of greatest concern when the
plaque is located on the carina or the apex of the bifurcation.
During treatment of the disease the plaque may shift from one side
of the carina to the other thereby shifting the obstruction from
one vessel to the alternate vessel.
[0009] In another prior art method of implanting stents, a "T"
stent procedure includes implanting a stent in the side branch
ostium of the bifurcation followed by stenting the main vessel
across the side branch and subsequently deforming the struts as
previously described, to allow blood flow and access into the side
branch vessel. Alternatively, a stent is deployed in the parent
vessel and across the side branch origin followed by subsequent
strut deformation as to access the side branch previously
described, and finally a stent is placed into the side branch
vessel. T stenting may be necessary in some situations in order to
provide further treatment and additional stenting in the side
branch vessel. This is typically necessitated when the disease is
concentrated at the origin of the jailed vessel. This procedure is
also associated with the same issues and risks previously described
when stenting only one vessel and deforming the struts through the
jailed vessel. In addition, since a conventional stent generally
terminates at right angles to its longitudinal axis, the use of
conventional stents to treat the origin of the previously jailed
vessel (typically the side branch vessel) may result in blocking
blood flow of the originally non-jailed vessel (typically the
parent vessel) or fail to provide adequate coverage of the disease
in the previously jailed vessel (typically a side branch vessel).
The conventional stent might be placed proximally in order to
provide full coverage around the entire circumference of the side
branch, however this leads to a portion of the stent extending into
the pathway of blood flow of the parent vessel. The conventional
stent might alternatively be placed distally to, but not entirely
overlaying the circumference of the origin of the side branch to
the diseased portion. Such a position of the conventional stent
results in a bifurcation that does not provide full coverage or has
a gap on the proximal side (the origin of the side branch) of the
vessel and is thus not completely supported. The only conceivable
situation that the conventional stent, having right-angled terminal
ends, could be placed where the entire circumference of the ostium
is supported or treated without compromising blood flow, is where
the bifurcation is formed of right angles, an uncommon occurrence.
In such scenarios, extremely precise positioning of the
conventional stent is required. This extremely precise positioning
of the conventional stent may result with the right angled terminal
end of the conventional stent overlying the entire circumference of
the ostium to the diseased portion without extending into a main
branch, thereby repairing the right-angled bifurcation.
[0010] To circumvent or overcome the problems and limitations
associated with conventional stents in the context of repairing
diseased bifurcated vessels, a stent that consistently overlays
most of the diseased area of the bifurcation and provides adequate
access to distal disease without subjecting the patient to any
undue risks may be employed. Such a stent would have the advantage
of providing adequate coverage at the proximal edge of the origin
of the side branch such that a conventional stent which terminates
at right angles to its longitudinal axis can be deployed in the
side branch or alternate vessel without leaving a significant gap
or overlap at the origin of the side branch. In addition, such a
stent allows access to all portions of the bifurcated vessel should
further interventional treatment be necessary.
[0011] In another prior art method for treating bifurcated vessels,
commonly referred to as the "Culotte technique," the side branch
vessel is first stented so that the stent protrudes into the main
or parent vessel. A dilatation is then performed in the main or
parent vessel to open and stretch the stent struts extending across
the lumen from the side branch vessel. Thereafter, a stent is
implanted in the side branch so that its proximal end overlaps with
the parent vessel. One of the drawbacks of this approach is that
the orientation of the stent elements protruding from the side
branch vessel into the main vessel is completely random. In
addition excessive metal coverage exists from overlapping strut
elements in the parent vessel proximal to the carina area.
Furthermore, the deployed stent must be recrossed with a wire
blindly and arbitrarily selecting a stent cell. When dilating the
main vessel the stent struts are randomly stretched, thereby
leaving the possibility of restricted access, incomplete lumen
dilatation, and major stent distortion.
[0012] In another prior art procedure, known as "kissing" stents, a
stent is implanted in the main vessel with a side branch stent
partially extending into the main vessel creating a
double-barrelled lumen of the two stents in the main vessel
proximal to the bifurcation. Another prior art approach includes a
so-called "trouser legs and seat" approach, which includes
implanting three stents, one stent in the side branch vessel, a
second stent in the distal portion of the main vessel, and a third
stent, or a proximal stent, in the main vessel just proximal to the
bifurcation.
[0013] All of the foregoing stent deployment assemblies suffer from
the same problems and limitations. Typically, there are uncovered
surface segments or overlapped struts on the main vessel and side
branch vessels between the stented segments, or there is excessive
coverage in the parent vessel proximal to the bifurcation. An
uncovered flap or fold in the intima or plaque will invite a
"snowplow" effect, representing a substantial risk for sub-acute
thrombosis, and the increased risk of the development of
restenosis. Further, where portions of the stent are left unapposed
within the lumen, the risk for subacute thrombosis or the
development of restenosis again is increased. The prior art stents
and delivery assemblies for treating bifurcations are difficult to
use and deliver making successful placement challenging. Further,
even where placement has been successful, the side branch vessel
can be "jailed" or covered so that there is impaired access to the
stented area for subsequent intervention. The present invention
solves these and other problems as will be shown.
[0014] In addition to problems encountered in treating disease
involving bifurcations for vessel origins, difficulty is also
encountered in treating disease confined to a vessel segment but
extending very close to a distal branch point or bifurcation which
is not diseased and does not require treatment. In such
circumstances, very precise placement of a stent covering the
diseased segment, but not extending into or obstructing the side
branch, may be difficult or impossible. The present invention also
offers a solution to this problem.
[0015] The stent of the present invention includes struts that make
up the rings and links, the struts having either uniform
cross-sections, or cross-sections having various widths and
thicknesses.
SUMMARY OF THE INVENTION
[0016] The invention provides for improved stent designs and stent
delivery catheter assemblies for repairing a main vessel and side
branch-vessel forming a bifurcation, without compromising blood
flow, thereby allowing access to all portions of the bifurcated
vessels should further interventional treatment be necessary. The
present invention includes a stent pattern having one or more
portals, various stent lengths and portal locations, a stent
delivery catheter assembly, radiopaque marker patterns on the stent
and/or catheter delivery system, and a method for delivering and
implanting the stent in a bifurcated vessel.
The Stent Pattern
[0017] The stent of the present invention includes a cylindrical
body having rings aligned along a longitudinal axis, where each
ring has a delivered diameter in which it is crimped or compressed
tightly onto the balloon catheter and an implanted diameter where
the stent is implanted in a bifurcated vessel.
[0018] The present invention is directed to an intravascular stent
that has a pattern or configuration that permits the stent to be
tightly compressed or crimped onto a catheter to provide an
extremely low profile and to prevent relative movement between the
stent and the catheter. The stent also is highly flexible along its
longitudinal axis to facilitate delivery through tortuous body
lumens, but which is stiff and stable enough radially in its
expanded condition to maintain the patency of a body lumen such as
an artery when the stent is implanted therein.
[0019] The stent of the present invention generally includes a
plurality of cylindrical rings that are interconnected to form the
stent. The stent typically is mounted on a balloon catheter if it
is balloon expandable or mounted on or in a catheter without a
balloon if it is self-expanding.
[0020] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and a cylindrical
plane defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links does not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side. The two balloons
can be of different lengths and diameters with the first balloon
being longer than the second balloon. In this embodiment, three
undulating links connect adjacent cylindrical rings. The undulating
portion or bend in two of the links of the portal region face in
opposite directions transverse to the longitudinal axis of the
stent. The undulating links connecting cylindrical rings in the
main body of the stent have undulating portions or bends that all
point in the same direction transverse to the longitudinal axis of
the stent. In another embodiment, at least one of the main body
cylindrical rings is connected by three undulating links, where the
undulating portion or bend of one of the links points in a
direction opposite to that of the other two undulating portions or
bends, however, all of the undulating portions or bends are
positioned transverse to the longitudinal axis of the stent. In
this embodiment, the width of the bar arms of the proximal end ring
have a first width, other rings have a second width, and certain
bar arms in the portal region rings have a third width. Varying the
width of the bar arms varies the flexibility of the stent in
particular regions.
[0021] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links does not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. In one aspect of the
invention, three undulating links connect adjacent cylindrical
rings except for the portal region, in which two undulating links
connect the ring in the portal region with the adjacent ring of the
main body of the stent. Further, the undulating portion or bend in
the two links of the portal region face in opposite directions
transverse to the longitudinal axis of the stent. The undulating
links connecting cylindrical rings in the main body of the stent
have undulating portions or bends that all point in the same
direction transverse to the longitudinal axis of the stent. In
another embodiment, at least one of the main body cylindrical rings
is connected by three undulating links, where the undulating
portion or bend of one of the links points in a direction opposite
to that of the other two undulating portions or bends, however, all
of the undulating portions or bends are positioned transverse to
the longitudinal axis of the stent. In another embodiment, a distal
section of the stent has a plurality of cylindrical rings attached
by undulating links as previously described. A central section,
includes the portal region, which is attached to a proximal section
of the stent by two undulating links, the undulating portion of
which points in opposite directions transverse to the longitudinal
axis of the stent. A proximal section of the stent includes
plurality of cylindrical rings, at least one of which has a
different pattern of U-shaped elements than the other cylindrical
rings in the proximal section. More specifically, a proximal end
ring includes U-shaped elements having a configuration different
than the U-shaped elements of the other cylindrical rings in the
proximal section, and the U-shaped elements of the proximal end
ring are substantially identical.
[0022] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links does not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. In one aspect of the
invention, three undulating links connect adjacent cylindrical
rings except for the portal region, in which two undulating links
connect the ring in the portal region with the adjacent ring of the
main body of the stent. Further, the undulating portion or bend in
the two links of the portal region face in opposite directions
transverse to the longitudinal axis of the stent. The undulating
links connecting cylindrical rings in the main body of the stent
have undulating portions or bends that all point in the same
direction transverse to the longitudinal axis of the stent. In
another embodiment, at least one of the main body cylindrical rings
are connected by three undulating links, where the undulating
portion or bend of one of the links points in a direction opposite
to that of the other two undulating portions or bends, however, all
of the undulating portions or bends are positioned transverse to
the longitudinal axis of the stent. In this embodiment, the stent
includes thirteen cylindrical rings, the proximal ring being
designated ring No. 1, the portal cylindrical ring being designated
No. 6, and the distal end ring being designated ring No. 13.
Referring to portal ring No. 6, two undulating links connect portal
ring No. 6 to distal section cylindrical ring No. 7. The undulating
portions of the two undulating links point in opposite directions,
both being transverse to the longitudinal axis of the stent. In
this embodiment, the undulating portions of the two links point
toward the portal region, which allows the adjacent U-shaped
elements that are outside the portal region to have a length longer
than the adjacent U-shaped elements inside the portal region. This
allows the bar arms on the longer U-shaped elements to expand more
when the stent is expanded and implanted in a bifurcated artery,
and it will reduce ring separation in the side branch. In another
embodiment, the proximal end ring is attached to the adjacent
cylindrical ring by two undulating connecting links. This provides
additional flexibility at the proximal end and also reduces the
likelihood of strut flaring during delivery and expansion of the
stent.
[0023] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links do not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. In one aspect of the
invention, three undulating links connect adjacent cylindrical
rings except for the portal region, in which two undulating links
connect the ring in the portal region with the adjacent ring of the
main body of the stent. Further, the undulating portion or bend in
the two links of the portal region face in opposite directions
transverse to the longitudinal axis of the stent. The undulating
links connecting cylindrical rings in the main body of the stent
have undulating portions or bends that all point in the same
direction transverse to the longitudinal axis of the stent. In
another embodiment, at least one of the main body cylindrical rings
are connected by three undulating links, where the undulating
portion or bend of one of the links points in a direction opposite
to that of the other two undulating portions or bends, however, all
of the undulating portions or bends are positioned transverse to
the longitudinal axis of the stent. In this embodiment, the portal
area or portal region is configured to be symmetrical about the
longitudinal axis of the stent to ensure even expansion. This axis
is centered within the portal. All of the cylindrical rings, except
the portal ring (the sixth ring from the proximal end of the stent)
and the ring proximal to it, have six crests or peaks connected by
three undulating links. The cylindrical rings in the proximal
section have a larger expansion diameter than the cylindrical rings
in the distal section to accommodate any post-dilatation using a
kissing balloon technique. In this embodiment, the portal
cylindrical ring and the cylindrical ring proximal to the portal
cylindrical ring are configured to have eight crests or peaks per
ring and are connected to each other by three undulating links. The
portal ring and the cylindrical ring proximal to the portal ring
are in phase. In one aspect of this embodiment, the proximal end
ring has wider struts or bar arms, shorter bar arms or struts than
other cylindrical rings of the stent, and all of the peaks or
crests have a keyhole design in order to reduce flaring at the
proximal end of the stent. The wider struts or bar arms increase
the radial strength of the proximal end ring, thereby making it
more difficult for the ring to lift or flare during delivery or
expansion of the stent. The keyhole crests or peaks, when crimped,
will provide more grip on the balloon. The shorter bar arms or
struts make it difficult for them to open and flare because of a
shorter lever arm. All of these factors, working together, reduce
flaring of the proximal end ring.
[0024] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links do not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon.
[0025] In this embodiment, the stent comprises three sections, a
proximal section, a portal section, and a distal section. Rings 1
to 4 in the proximal section all are oriented opposite to or out of
phase with rings 7-12 in the distal section. This allows the
W-shaped portions of the rings in the proximal section to be
tailored to allow a smooth guide pull-back when delivering the
stent. In one aspect of the invention, the undulating links between
rings 4 and 5 are substantially longer than the undulating links
connecting all of the other rings since the W-shaped portions and
U-shaped portions in ring 4 are out of phase with the W-shaped
portions and U-shaped portions in ring 5. The longer links allow
the fourth and fifth rings to extend further into the side branch
vessel when the stent is expanded and implanted in the bifurcated
vessel. In another embodiment, at least two of the links connecting
the fourth and fifth rings are linear, thereby insuring that the
distance between the two rings stays constant throughout delivery
and when the portal region is expanded toward the side branch
vessel. In another embodiment, at least some of the U-shaped
portions in the fourth and fifth rings have substantially longer
bar arms in order to provide more coverage as that portion of the
rings expand into the opening to the side branch vessel.
[0026] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links do not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. After deployment of
the bifurcated stent into the main vessel, with the portal region
stenting the vessel wall opposite the carina of the bifurcation, a
second stent can be implanted in the side branch vessel, so that
the proximal end of the second stent abuts the struts of the portal
region. In this embodiment, a proximal radiopaque marker is
positioned on the proximal end of the bifurcated stent and a
radiopaque marker on the shaft of the delivery catheter for the
second (side branch) stent aligns with the radiopaque mark on the
proximal end of the bifurcated stent. The distance between the
radiopaque marker on the delivery catheter and the proximal end of
the second stent substantially equals the distance between the
proximal radiopaque marker on the bifurcated stent and the distal
end of the portal region or portal cylindrical ring. Thus, the
second stent can be deployed in the side branch vessel so that the
proximal end of the second stent abuts the portal cylindrical ring.
In another embodiment, two radiopaque markers are placed on the
proximal end of the bifurcated stent so that as the delivery
catheter advances the second stent into the side branch vessel, the
radiopaque marker on the delivery catheter will come into alignment
between the two radiopaque markers on the proximal end of the
bifurcated stent. The two radiopaque markers should be
approximately 180.degree. apart. When the two radiopaque markers on
the proximal end of the bifurcated stent come into alignment with
the radiopaque marker on the shaft of the catheter delivering the
second stent (side branch stent), the proximal end of the second
stent will be aligned with the distal end of the portal ring on the
bifurcated stent. In another embodiment, one or two radiopaque
markers are positioned on the distal end of the portal cylindrical
ring which has flared and covers the carina to the bifurcated
vessel. As the delivery catheter advances the second stent into the
side branch vessel, a radiopaque marker on the delivery catheter,
which has been positioned to align with the proximal end of the
second stent, comes into alignment with the one or two radiopaque
markers on the distal end of the portal cylindrical ring. Once the
radiopaque markers on the portal end of the bifurcated stent and
the catheter are aligned, the second or side branch stent can be
deployed so that the proximal end of the second stent abuts the
distal end of the portal ring.
[0027] In another embodiment, one or two radiopaque markers are
positioned on the distal end of the portal cylindrical ring which
has flared and covers the carina to the bifurcated vessel. As the
delivery catheter advances the second stent into the side branch
vessel, a radiopaque marker on the proximal edge of the second
stent comes into alignment with the one or two radiopaque markers
on the distal end of the portal cylindrical ring. Once the
radiopaque markers on the portal end of the bifurcated stent and
the proximal end of the second stent are aligned, the second or
side branch stent can be deployed so that the proximal end of the
second stent abuts the distal end of the portal ring.
[0028] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links do not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. In addition to, or in
lieu of, the portal region in approximately the central portion of
the stent, a proximal portal region, a central portal region,
and/or a distal portal region are provided in a bifurcated stent.
In this embodiment, the proximal portal region is positioned
between cylindrical rings No. 2 and 3 (with the proximal end ring
being ring No. 1 and the distal end ring being ring No. 13), the
central portal region is positioned between cylindrical rings No. 8
and 9, and the distal portal region is positioned between
cylindrical rings No. 12 and 13. Each of the portals can be
identified under fluoroscopy by adding radiopaque material to the
undulating links surrounding the portal area.
[0029] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and cylindrical plane
defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
connecting link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. The undulating links have a curved portion that extends
transverse to the stent longitudinal axis. More specifically, the
curved portion extends in a transverse direction (or
circumferentially) such that it would intersect with the adjacent
U-shaped element, however, the adjacent U-shaped element is shorter
in length than other U-shaped elements in the same ring. Thus, when
the stent is compressed or crimped onto the catheter, the
undulating portion of the links do not overlap or intersect with
the adjacent U-shaped element since that element is shorter in
length than other U-shaped elements in the same ring. With this
structure, the stent can be compressed or crimped to a much tighter
or smaller diameter onto the catheter, which permits low profile
delivery as well as tight crimping force on the catheter to reduce
the likelihood of movement between the stent and the catheter
during delivery and prior to implanting the stent in the vessel. In
one aspect of the invention, the portal region is formed between
two adjacent cylindrical rings and is configured to receive a side
branch balloon of a balloon catheter. In this embodiment, a first
balloon of a balloon catheter extends through the main body of the
stent, and a second balloon extends through the portal area so that
the two balloons are substantially side by side, with the first
balloon being longer than the second balloon. In order to identify
the portal region under fluoroscopy, a polymer radiopaque coating
covers the stent struts so that the physician can more accurately
locate and position the side branch balloon relative to the side
branch vessel. In one embodiment, approximately sixty percent or
more of tungsten is loaded into a polymer which is then coated onto
individual stent struts around the portal region of the stent in
order to provide a radiopaque marker for the physician. The polymer
must be flexible enough to expand when the stent expands and so
that it does not adversely affect the coating integrity. In one
embodiment, the radiopaque marker polymer is coated onto only
straight portions of the struts so that expansion of the stent will
not cause the polymer to dislodge.
[0030] In one embodiment, each of the cylindrical rings making up
the stent has a proximal end and a distal end and a cylindrical
plane defined by a cylindrical outer wall surface that extends
circumferentially between the proximal end and the distal end of
the cylindrical ring. Generally, the cylindrical rings have a
serpentine or undulating shape which includes at least one U-shaped
element, and typically each ring has more than one U-shaped
element. The cylindrical rings are interconnected by at least one
undulating link which attaches one cylindrical ring to an adjacent
cylindrical ring. The undulating links are highly flexible and
allow the stent to be highly flexible along the stent longitudinal
axis. At least some of the undulating links have a curved portion
that extends transverse to the stent longitudinal axis for a
predetermined distance that coincides with one of the U-shaped
elements. More specifically, the curved portion extends in a
transverse direction (or circumferentially) such that it would
intersect with the corresponding U-shaped element, however, the
corresponding U-shaped element is shorter in length than other
U-shaped elements in the same ring. Thus, when the stent is
compressed or crimped onto the catheter, the curved portions do not
overlap or intersect with the adjacent U-shaped element since that
element is shorter in length than similar U-shaped elements in the
particular ring. In this manner, the stent can be compressed or
crimped to a much tighter or smaller diameter onto the catheter
which permits low profile delivery as well as a tight gripping
force on the catheter to reduce the likelihood of movement between
the stent and the catheter during delivery and prior to implanting
the stent in the vessel. In one embodiment, the links have an
undulation or bend. The undulating links can include bends
connected by substantially straight portions wherein the
substantially straight portions are substantially perpendicular to
the stent longitudinal axis. The undulating links are connected to
one ring by a straight portion and to an adjacent ring by a curved
portion.
[0031] Not only do the undulating links that interconnect the
cylindrical rings provide flexibility to the stent, but the number
of links and the positioning of the links also enhances the
flexibility by allowing uniform flexibility when the stent is bent
in any direction along its longitudinal axis. Uniform flexibility
along the stent derives in part from the links of one ring being
circumferentially offset from the links in an adjacent ring.
Further, the cylindrical rings are configured to provide
flexibility to the stent in that portions of the rings can flex or
bend and tip outwardly as the stent is delivered through a tortuous
vessel.
[0032] In one embodiment, the cylindrical rings are formed of a
plurality of peaks and valleys, where the valleys of one
cylindrical ring are circumferentially offset from the valleys of
an adjacent cylindrical ring. In this configuration, at least one
undulating link attaches each cylindrical ring to an adjacent
cylindrical ring so that at least a portion of the undulating link
is positioned within one of the valleys and it attaches the valley
to an adjacent peak.
[0033] While the cylindrical rings and undulating links generally
are not separate structures, they have been conveniently referred
to as rings and links for ease of identification. Further, the
cylindrical rings can be thought of as comprising a series of U's,
W's and Y-shaped structures in a repeating pattern. Again, while
the cylindrical rings are not divided up or segmented into U's, W's
and Y's, the pattern of the cylindrical rings resemble such
configuration. The U's, W's and Y's promote flexibility in the
stent primarily by flexing and by tipping radially outwardly as the
stent is delivered through a tortuous vessel.
[0034] The undulating links are positioned so that the curved
portion of the link is outside the W-shaped portion. Since the
curved portion does not substantially expand (if at all) when the
stent is expanded, it will continue to provide good vessel wall
coverage even as the curved part of the W-shaped portion spreads
apart as the stent is expanded. The curved portion of the link
extends in a direction transverse to the stent longitudinal axis
for a distance that positions it adjacent and proximal to the peak
of a U-shaped element. These U-shaped elements have struts that are
shorter than the struts of the other U-shaped elements in the same
cylindrical ring so that as the stent is compressed the curved
portion of the link does not overlap the adjacent U-shaped
element.
[0035] The number and location of undulating links that
interconnect adjacent cylindrical rings can be varied as the
application requires. Since the undulating links typically do not
expand when the cylindrical rings of the stent expand radially
outwardly, the links are free to continue to provide flexibility
and also to provide a scaffolding function to assist in holding
open the artery. The addition or removal of the undulating links
has very little impact on the overall longitudinal flexibility of
the stent. Each undulating link is configured so that it promotes
longitudinal flexibility whereas some prior art connectors
significantly reduce longitudinal flexibility of the stent.
[0036] The cylindrical rings of the stent are plastically deformed
when expanded when the stent is made from a metal that is balloon
expandable. Typically, the balloon-expandable stent is made from a
stainless steel alloy, cobalt chromium, tungsten, polymers, or
similar material.
[0037] Similarly, the cylindrical rings of the stent expand
radially outwardly when the stent is formed from superelastic
alloys, such as nickel-titanium (NiTi) alloys. In the case of
superelastic alloys, the stent expands upon application of a
temperature change or when a stress is relieved, as in the case of
a pseudoelastic phase change.
[0038] Further, because of the positioning of the links, and the
fact that the links do not expand or stretch when the stent is
radially expanded, the overall length of the stent is substantially
the same in the unexpanded and expanded configurations. In other
words, the stent will not substantially shorten upon expansion.
[0039] The stent may be formed from a tube by laser cutting the
pattern of cylindrical rings and undulating links in the tube. The
stent also may be formed by laser cutting a flat metal sheet in the
pattern of the cylindrical rings and links, and then rolling the
pattern into the shape of the tubular stent and providing a
longitudinal weld to form the stent.
[0040] The stent of the present invention includes struts that make
up the rings and links, the struts having either uniform
cross-sections, or cross-sections having various widths and radial
thicknesses.
The Stent Delivery Catheter
[0041] The present invention also includes a stent delivery
catheter assembly for repairing bifurcated vessels including an
elongated catheter body which has a proximal catheter shaft, an
intermediate section or mid-section, and a distal section. The
catheter assembly contains an over-the-wire (OTW) guide wire lumen
extending from the proximal catheter hub to one of the distal tips
of the distal end of the catheter. The catheter assembly also
includes a rapid exchange (Rx) guide wire lumen which extends from
the proximal end of the mid-section to one of the distal tips of
the distal end of the catheter. The proximal catheter shaft also
contains an inflation lumen which extends from the proximal hub of
the proximal catheter shaft to the mid-section of the catheter and
is in fluid communication with the inflation lumen contained within
the mid-section. The mid-section contains lumens for both the OTW
and the Rx guide wire lumen. The Rx guide wire lumen begins at
about the proximal section of the intermediate shaft and extends to
one of the distal tips of the distal catheter shaft. In an
alternative embodiment, the Rx guidewire lumen is replaced by a
fixed wire design having a fixed guidewire with a distal section
permanently secured to a distal section of the catheter branch. The
OTW guide wire lumen extends through the intermediate section of
the catheter and extends proximally to the catheter hub connected
to the proximal catheter shaft and extends distally to one of the
tips of the distal section of the catheter. The distal section of
the catheter consists of two shafts extending from the distal end
of the mid-shaft to the distal end of the catheter tips. Each shaft
has a balloon connected adjacent the distal end followed by a tip
connected to the distal end of the balloon. Each shaft contains a
guide wire lumen and an inflation lumen. The inflation lumen of
each shaft is in fluid communication with the inflation lumen of
the mid-shaft. One of the shafts of the distal section contains an
Rx guide wire lumen, which extends proximally through the
mid-section of the catheter and exits at about the proximal end of
the mid-section of the catheter, the Rx guide wire lumen also
extends distally to one of the tips of the distal section of the
catheter. The other shaft of the distal section contains an OTW
guide wire lumen, which extends proximally through the mid-section
and proximal section of the catheter and exits at the proximal hub
connected to the distal end of the proximal catheter section, the
OTW guide wire lumen also extends distally to one of the tips of
the distal section of the catheter. The distal section of the
catheter includes two balloons. One balloon is longer and is
connected to one of the shafts of the distal catheter section. The
long balloon is connected to the catheter shaft such that the
inflation lumen of the shaft is in fluid communication with the
balloon and the guide wire lumen contained within the shaft extends
through the center of the balloon. The proximal section of the
balloon is sealed to the distal end of the shaft and the distal end
of the balloon is sealed around the outside of the guide wire lumen
or inner member running through the center of the balloon. The
proximal and distal seals of the balloon allow for fluid
pressurization and balloon inflation from the proximal hub of the
catheter. The short balloon is connected in the same manner as the
long balloon described above to the alternate shaft of the distal
section of the catheter. Each balloon has a tip extending from
their distal ends. The tips are extensions of the inner members
extending through the center of the balloon and contain a lumen for
a guide wire associated with each guide wire lumen. The distal end
of the catheter has two tips associated with their respective
balloons and the guide wire lumen or inner member. One tip is
longer and contains a coupler utilized for joining the tips during
delivery of the previously described stent.
[0042] The stent of the present invention is crimped or compressed
onto the long balloon and the short balloon such that the long
balloon extends through the distal opening and the proximal opening
in the stent, while the short balloon extends through the proximal
opening and the central opening of the stent.
[0043] In one embodiment, a balloon catheter of the invention has
one or more polymeric radiopaque markers, and generally comprises
an elongated catheter shaft having a branched distal section with a
first and a second branch configured for releasably coupling
together to form a coupled configuration, an inflation lumen, and a
joining wire lumen extending at least within the first branch of
the branched distal section; a first balloon on the first branch
with an inflatable interior in fluid communication with the
inflation lumen, and a second balloon on the second branch with an
inflatable interior in fluid communication with the inflation
lumen. In a presently preferred embodiment, the polymeric
radiopaque marker provides for visualizing a distal end section of
the branch of the catheter shaft configured for placement in the
side branch of the patient's vessel (e.g., the catheter branch
which has the short balloon thereon), to facilitate accurately
positioning the catheter and stent thereon prior to unjoining the
two distal tips of the catheter. The polymeric radiopaque marker is
a blend of polymeric and radiopaque materials, which provides a
highly bright (under fluoroscopy) yet flexible marker. As a result,
the soft flexible marker does not create a large stiffness
transition disadvantageously affecting the catheter's ability to be
maneuvered to a desired location within the patient's tortuous
anatomy. The polymeric radiopaque tip marker is preferably secured
to the shaft such that it provides a smooth transition in stiffness
at the catheter distal tip which improves the overall
deliverability of the stent delivery catheter. In a presently
preferred embodiment, the marker is a ring on or in a distal end
section of the shaft. However, a variety of suitable configurations
can be used including an embodiment in which the polymeric
radiopaque marker comprises a distal tip member defining the distal
end of the lumen of the catheter branch.
[0044] Additionally, the polymeric radiopaque side branch tip
marker facilitates determining and correcting the rotational
orientation of the catheter relative to the opening of the side
branch vessel. As the catheter assembly is advanced through
tortuous coronary arteries, over the Rx guide wire, the central
opening of the stent may or may not always be perfectly aligned
with the side branch take-off (i.e., the opening to the side branch
vessel). If the central opening of the stent is in alignment with
the side branch take-off it is said to be "in phase" and represents
the ideal position for stenting the main branch vessel and the
opening to the side branch vessel. When the central opening of the
stent and the side branch take-off are not aligned it is said to be
"out of phase" and depending upon how many degrees out of phase,
the stent may require repositioning or reorienting so that the
central opening more closely coincides with the side branch
take-off. The polymeric radiopaque tip marker provides for
visualization of the position of the side branch distal tip of the
catheter, with the two distal tips of the catheter in the joined or
the unjoined configuration and without disadvantageously increasing
the stiffness of the catheter distal end, and thereby facilitates
aligning the catheter to put it "in phase".
[0045] In a presently preferred embodiment, the polymeric
radiopaque tip marker is formed of a polymeric blend having a high
weight percent loading of radiopaque material, as described in U.S.
patent application Ser. No. 10/945,637, incorporated by reference
herein in its entirety. The polymeric blend provides a highly
radiopaque and yet highly flexible marker. In one embodiment, the
fill ratio is about 90.8 weight percent (34.9 volume percent) to
about 93.2 weight percent (42.7 volume percent) of radiopaque
material. However, in an alternative embodiment, a smaller amount
of radiopaque material is used to optimize the flexibility of the
marker or decrease the image intensity under fluoroscopy. Thus, the
fill ratio is preferably selected to balance the flexibility and
radiopacity of the distal tip marker.
[0046] The marker relies on the use of radiopaque materials with a
preselected particle shape and a preselected particle size
distribution as well as the inclusion of one or more additives in
the polymer/radiopaque agent blend, as discussed in the 10/945,637
Application, incorporated by reference above. A multifunctional
polymeric additive is added to the composition in order to enhance
the wetting, adhesive and flow properties of the individual
radiopaque particles by the polymer so as to cause each particle to
be encapsulated by the polymer and thereby allow the polymer to
form a continuous binder. An antioxidant may optionally be added in
order to preserve the high molecular weight of the polymer matrix
as it is exposed to the high temperatures and shear stresses
associated with the compounding and extrusion processes.
[0047] In a presently preferred embodiment, the polymeric
radiopaque blend is formed of a blend of a polyether block amide
(PEBAX) polymer and radiopaque tungsten particles. However, a
variety of suitable polymers and radiopaque materials may be used
for the polymeric radiopaque blend. The PEBAX polymeric material
provides a soft, flexible marker that is compatible with the
presently preferred materials (e.g., polyamides such as PEBAX) used
to form a distal tip of the stent delivery catheter of the
invention, so that the polymeric radiopaque tip marker can be
melt/fusion bonded to the catheter shaft without the use of
adhesives. The polymeric blend can be extruded to form the desired
shape of the marker.
[0048] In a presently preferred embodiment, the polymeric blend
provides a marker which appears visually different under
fluoroscopy from the catheter's balloon radiopaque markers (e.g.,
the radiopaque marker bands which indicate the working length of
the balloon and/or the alignment of the stent on the balloon). For
example, in one embodiment, the balloon radiopaque marker(s)
comprise a metal (e.g., Pt/Ir) band which thus has a different
composition than the polymeric radiopaque blend and which appears
as a sharply defined rectangular band under fluoroscopy, whereas
the polymeric radiopaque tip marker appears as a rounded, less
sharply defined image. Additionally, in one embodiment, the length
of the polymeric radiopaque tip marker is different than (e.g.,
longer than) the balloon radiopaque marker(s).
[0049] In one embodiment, the bifurcated distal section of the
catheter has at least one secured portion along which the first and
second branches of the distal shaft section are permanently secured
together. The secured portion is located proximal to the inflatable
section of the balloons, and preferably distal to the proximal end
of the branched distal shaft section (and distal to the
intermediate section of the shaft) so that the branched distal
shaft section has an unsecured portion which is proximally adjacent
to the secured portion. In a presently preferred embodiment, the
two shafts are permanently secured together at least in part by a
tubular outer band member such as, for example, a length of heat
shrink tubing. A first band member is preferably located adjacent
to the proximal-most balloon end, and a second band member is
preferably located proximal thereto. For example, in a presently
preferred embodiment, the second band member is located at about
the half-way point along the length of the distal shaft section
between the proximal end of the balloons and the distal end of the
intermediate shaft section. Adhesive may additionally or
alternatively be used to join the branches together. The secured
distal branches of the catheter provide improved deliverability by
preventing or inhibiting the tendency of the two outer members of
the distal shafts to separate during advancement of the catheter
within the patient's tortuous anatomy. As a result, the catheter
has the deliverability and manufacturability advantages provided by
the two shafts extending separately from the intermediate shaft
section, in combination with the deliverability advantages provided
by securing the two shafts together at one or more location between
the balloons and the intermediate shaft section. Additionally, the
secured distal shafts of the catheter prevent or inhibit damage to
the vessel wall which can otherwise occur if the end of the stent
is caused to become flared. Such flaring at the end of the stent
can occur as the proximal ends of the balloons move a
disadvantageously large amount relative to one another during
delivery and deployment of the stent.
[0050] A joining wire slidably disposed within a branch (typically
the OTW branch) of the catheter releaseably joins the distal tips
of the two branches of the catheter together for advancement within
the patient's anatomy. The joining wire is locked to the proximal
end of the catheter assembly to keep the two distal tips together
during delivery to ensure that the stent remains securely mounted
on the balloons. With the stent in position for deployment within
the body lumen, the joining wire is at least partially retracted to
release the two branch tips. However, the ability to advance the
joining wire within the branch vessel and use the joining wire to
seat the stent into position within the vessel depends on the
member used to lock the joining wire to the proximal end of the
catheter assembly. For example, a joining wire which has a proximal
end which is trimmed and secured to a connector at the proximal end
of the catheter assembly must therefore be fully withdrawn and
replaced with a separate guidewire for use in seating the stent
into position within the vessel. In one embodiment of the
invention, the joining wire also functions as a guidewire, with a
proximal end slidably disposed out the proximal end of a guidewire
locking mechanism releaseably securing the joining guidewire to the
proximal end of the catheter. For example, in one embodiment, the
guidewire locking mechanism has a collet member with a radially
collapsible slotted head positioned within a proximal adapter or
fitting on the proximal end of the catheter shaft. The guidewire
locking mechanism saves physician time and effort by avoiding the
removal and replacement of the joining wire. Additionally, the
guidewire locking mechanism preferably is configured to facilitate
manufacture of the catheter assembly and loading of the joining
guidewire into the catheter. In one embodiment, the guidewire
locking mechanism is in the locked mode with the distal end of the
joining guidewire positioned distally beyond the distal end of the
catheter first branch. In this configuration, the first branch and
joining guidewire act as a fixed wire device, which is particularly
preferred for delivering low profile devices through long, tortuous
or diffusely deceased vasculature.
[0051] In one embodiment, the guidewire locking mechanism comprises
a guidewire locking torque handle ("torquer") on a proximal end
section of the joining guidewire. The torquer reversibly engages
the joining guidewire to provide a finger hold for manipulating the
joining guidewire. Additionally, the torquer releaseably connects
to a proximal end of the catheter assembly (e.g. to the proximal
adapter) to thereby releasably lock the joining guidewire to the
catheter. In the locked configuration, the joining guidewire is
held in place relative to the catheter, and in the unlocked
configuration the joining guidewire is free to slide within the
catheter with the torquer connected to the joining guidewire to
provide a handle for the physician facilitating the independent
manipulation of the joining guidewire. As a result, the catheter
assembly limits procedure time and steps, with a joining wire that
functions as both a useable guidewire that can be steered, and as a
joining wire that releasably joins the distal tips of the two
shafts together. Although discussed primarily in terms of use with
a bifurcated stent delivery catheter, the guidewire locking torque
handle can be used with a variety of suitable catheters having an
over-the-wire shaft design in which the guidewire is slidably
disposed in the catheter guidewire lumen. Therefore, with the
guidewire locking torque handle tightened down onto the guidewire
and simultaneously secured to the proximal end of an over-the-wire
catheter (e.g., to the proximal adapter/hub), the guidewire locking
torque handle of the invention provides a stable and fixed position
and relation between the guidewire and catheter, so that the
catheter can be advanced or withdrawn from the body lumen while
maintaining its position relative to the guidewire.
Delivering and Implanting the Stent
[0052] A method of delivering and implanting the stent mounted on
the catheter assembly is contemplated by the present invention. The
bifurcated catheter assembly of the present invention provides two
separate balloons in parallel which are advanced into separate
passageways of an arterial bifurcation and the balloons are
inflated either simultaneously or independently (or a combination
thereof) to expand and implant the stent. More specifically, and in
keeping with the invention, the catheter assembly is advanced
through a guiding catheter (not shown) until the distal end of the
catheter assembly reaches the ostium to the coronary arteries. An
Rx guide wire is advanced into the coronary arteries to a point
distal of the bifurcation or target site. In a typical procedure,
the Rx guide wire will already be positioned at the target site
after a pre-dilatation procedure. The catheter assembly is advanced
over the Rx guide wire so that the catheter distal end is just
proximal to the opening to the side branch vessel. Up to this point
in time, the OTW guide wire (or mandrel or joining wire) remains
within the catheter assembly and within the coupler so that the
long balloon and the short balloon of the catheter assembly remain
adjacent to one another to provide a low profile and prevent wire
wrap. As the catheter assembly is advanced to the bifurcated area,
the coupler moves axially relative to the distal end of the OTW
guide wire (or mandrel or joining wire) a small distance
(approximately 0.5 mm up to about 5.0 mm), but not pull completely
out of the coupler, making it easier for the distal end of the
catheter to negotiate tortuous turns in the coronary arteries.
Thus, the slight axial movement of the coupler relative to the OTW
guide wire (or mandrel or joining wire) distal end allows the tips
to act or move independently, thereby increasing flexibility over
the tips joined rigidly and it aids in the smooth tracking of the
catheter assembly over the Rx guide wire. The proximal end of the
OTW guide wire is releasably attached to the proximal hub as
previously described. The OTW guide wire (or mandrel or joining
wire) is removed or withdrawn proximally from the coupler, thereby
uncoupling the long balloon and the short balloon. Thereafter, the
OTW guide wire is advanced distally into the side branch vessel so
that the catheter assembly can next be advanced distally over the
Rx guide wire in the main vessel and the OTW guide wire in the side
branch vessel. The separation between the Rx guide wire and the OTW
guide wire allows the long balloon and the short balloon to
separate slightly as the catheter assembly is further advanced over
the Rx guide wire and the OTW guide wire. The catheter assembly
advances distally until it reaches a point where the central
opening on the stent is approximately adjacent to the opening to
the side branch vessel, so that the catheter assembly can no longer
be advanced distally since the balloons push against the carina and
are somewhat constrained by the stent. One or more high percent
tungsten/radiopaque markers are placed on the distal portion of the
PEBAX balloon catheter assembly to aid in positioning the stent
with respect to the bifurcation or target site. Once the long and
short balloons with the stent mounted thereon are positioned in the
main vessel just proximal to the side branch vessel, the long
balloon and the short balloon are next inflated simultaneously or
independently (or a combination thereof), to expand the stent in
the main vessel and the opening to the side branch vessel. The
central section of the stent is expanded into contact with the
opening to the side branch vessel and the central opening should
substantially coincide with the opening to the side branch vessel
providing a clear blood flow path through the proximal opening of
the stent and through the central opening into the side branch
vessel. By inflating the long balloon and the short balloon
substantially simultaneously, plaque shifting is avoided and access
to the side branch is better preserved.
[0053] As discussed above, as the catheter assembly is advanced
through tortuous coronary arteries, over the Rx guide wire, the
central opening of the stent may or may not always be perfectly
aligned with the opening to the side branch vessel, and may thus be
"out of phase," and depending upon how many degrees out of phase,
the stent may require repositioning or reorienting so that the
central opening more closely coincides with the opening to the side
branch vessel. The orientation of the central opening of the stent
with respect to the opening to the side branch vessel can range
anywhere from a few degrees to 180.degree.. If the central opening
of the stent is more than 90.degree. out of phase with respect to
the opening to the side branch vessel, it may be difficult to
position the radiopaque marker, and thus the linear or longitudinal
position of the stent. When the central opening is in the out of
phase position, the stent of the invention still can be implanted
and the central opening will expand into the opening of the side
branch vessel and provide adequate coverage. In cases where the
system is more than 90.degree. out of phase, the Rx and OTW guide
wires will be crossed causing a distal torque to be applied to help
the system to rotate in phase. In the event rotation does not
occur, the system can be safely deployed with adequate coverage and
support as long as the radiopaque markers located on the distal end
of the catheter reach the proper positioning as can be detected
under fluoroscopy. The unique and novel design of the catheter
assembly and the stent of the present invention minimizes the
misalignment so that the central opening of the stent generally
aligns with the opening to the side branch vessel, and is capable
of stenting the opening to the side branch vessel even if the
central opening is out of phase from the opening of the side branch
vessel.
[0054] One aspect of the invention is directed to a method of
delivering a stent to a patient's bifurcated blood vessel,
generally comprising introducing and advancing within a patient
blood vessel a stent delivery balloon catheter having a polymeric
radiopaque distal tip marker secured to the first branch (e.g.,
side branch), and fluoroscopically imaging the polymeric radiopaque
distal tip marker to determine the alignment of the first branch
balloon relative to an opening of a side branch of the patient's
blood vessel. Under fluoroscopy, the image of the polymeric
radiopaque distal tip marker facilitates adjusting the alignment of
the first branch balloon relative to the side branch opening of the
blood vessel both before and after the two distal tips of the
catheter are uncoupled. It also facilitates placement of a wire in
the side branch vessel after the joining mandrel is removed by
making visible the tip where the wire will exit the catheter.
[0055] After the stent of the present invention has been implanted
at the bifurcation, if necessary a second stent can be implanted in
the side branch vessel so that the second stent abuts the central
opening of the stent of the present invention.
[0056] As disclosed herein, there are multiple embodiments of a
bifurcated stent and stent delivery catheter. The specific
embodiments are not intended to be limiting, but have a wide range
of applications. Accordingly, the stents disclosed herein can be
delivered with other types of balloon catheters, and the balloon
catheters disclosed herein can be used for multiple purposes
including expanding or dilating an artery or delivering stents
having configurations other than those disclosed herein. The stents
also can be post-dilated using other catheters of different sizes
in either the main branch or the side branch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is an elevational view of a bifurcation in which a
prior art "T" stent is in a side branch ostium followed by the
stenting of the main vessel across the branch ostium.
[0058] FIG. 2 is an elevational view of a bifurcation in which
"touching" prior art stents are depicted in which one stent is
implanted in the side branch, a second stent implanted in a distal
portion of the main vessel next to the branch stent, with
interrupted placement of a third stent implanted more proximally in
the main vessel.
[0059] FIG. 3 is an elevational view of a bifurcation depicting
"kissing" stents where a portion of one stent is implanted in both
the side branch and the main vessel and adjacent to a second stent
implanted in the main vessel creating a double-barreled lumen in
the main vessel proximal to the bifurcation.
[0060] FIG. 4 is an elevational view of a prior art "trouser legs
and seat" stenting approach depicting one stent implanted in the
side branch vessel, a second stent implanted in a proximal portion
of the main vessel, and a close deployment of a third stent distal
to the bifurcation leaving a small gap between the three stents of
an uncovered luminal area.
[0061] FIG. 5A is an elevational view of a bifurcation in which a
prior art stent is implanted in the side branch vessel.
[0062] FIG. 5B is an elevational view of a bifurcation in which a
prior art stent is implanted in the side branch vessel, with the
proximal end of the stent extending into the main vessel.
[0063] FIG. 6A is an elevational view of a stent in a flattened
condition and depicting the portal region of a bifurcated
stent.
[0064] FIG. 6B is a perspective view depicting the stent of FIG. 6A
rolled into a cylinder.
[0065] FIG. 7A is an elevational view of a stent in a flattened
condition and depicting the portal region of a bifurcated
stent.
[0066] FIG. 7B is a perspective view depicting the stent of FIG. 7A
rolled into a cylinder.
[0067] FIG. 8A is an elevational view of a stent in a flattened
configuration depicting a bifurcated stent.
[0068] FIG. 8B is an elevational view of a stent in a flattened
configuration depicting a bifurcated stent.
[0069] FIG. 9 is an elevational view of a stent in a flattened
configuration depicting the portal region of a bifurcated
stent.
[0070] FIG. 10 is an elevational view of a stent in a flattened
configuration depicting a bifurcated stent.
[0071] FIG. 11 is an elevational view of a stent in a flattened
configuration depicting a bifurcated stent.
[0072] FIG. 12 is an elevational view of a stent in a flattened
configuration in which the bar arms of some of the peaks and some
of the links in the portal region are substantially longer relative
to other embodiments.
[0073] FIG. 13 is an elevational view of a stent in a flattened
configuration in which the bar arms of some of the peaks and some
of the links in the portal region are substantially longer relative
to other embodiments.
[0074] FIG. 14 is a schematic of a bifurcated stent implanted at a
bifurcation and a second stent (or side branch stent) being
delivered in the side branch vessel.
[0075] FIG. 15 is a schematic of a bifurcated stent implanted at a
bifurcation and a second stent (or side branch stent) being
delivered in the side branch vessel.
[0076] FIG. 16 is a schematic of a bifurcated stent implanted at a
bifurcation and a second stent (or side branch stent) being
delivered in the side branch vessel.
[0077] FIG. 17 is a schematic of a bifurcated stent implanted at a
bifurcation and a second stent (or side branch stent) being
delivered in the side branch vessel.
[0078] FIGS. 18A, 18B, 18C, and 18D are schematic diagrams of
bifurcated vessels showing plaque in the region of the
bifurcation.
[0079] FIGS. 18E, 18F, 18G, and 18H show various embodiments of
prior art stents for treating bifurcated vessels.
[0080] FIG. 19 is a schematic view of a bifurcated stent in a
flattened configuration depicting radiopaque markers in the portal
region.
[0081] FIG. 20 is a schematic view of a bifurcated stent in a
flattened configuration depicting radiopaque markers in the portal
region.
[0082] FIG. 21 is a schematic view of a bifurcated stent in a
flattened configuration depicting radiopaque markers in the portal
region.
[0083] FIG. 22 is an elevational view of a stent in a flattened
configuration depicting portions of a metallic stent covered with a
tungsten loaded polymer to increase radiopacity.
[0084] FIG. 23 is an elevational view of the catheter assembly for
delivering and implanting the stent of the invention.
[0085] FIG. 24 is a cross-sectional view taken along lines 24-24
depicting the cross-section of the proximal shaft of the
catheter.
[0086] FIG. 25 is a cross-sectional view taken along lines 25-25
depicting the cross-section of a portion of the catheter shaft.
[0087] FIG. 26A is a cross-sectional view taken along lines 26A-26A
depicting the cross-section of the Rx catheter shaft.
[0088] FIG. 26B is a cross-sectional view taken along lines 26B-26B
depicting the cross-section of the over-the-wire shaft.
[0089] FIG. 27 is a longitudinal cross-sectional view of the
coupler.
[0090] FIG. 28A is a longitudinal cross-sectional view depicting a
portion of the catheter distal end including the radiopaque
markers.
[0091] FIG. 28B is a transverse cross-sectional view taken along
lines 28B-28B depicting the inner member and long balloon.
[0092] FIG. 29 is an elevational view of one embodiment of the
catheter assembly for delivering and implanting the stent of the
invention.
[0093] FIG. 30 is a transverse cross-sectional view taken along
lines 30-30 depicting the proximal shaft section of the
catheter.
[0094] FIG. 31 is a transverse cross-sectional view taken along
lines 31-31 depicting the mid- or intermediate shaft section of the
catheter.
[0095] FIG. 31A is a transverse cross-sectional view taken along
lines 31A-31A depicting the first distal outer member.
[0096] FIG. 31B is a transverse cross-sectional view taken along
lines 31B-31B depicting the second distal outer member.
[0097] FIG. 32 is a transverse cross-sectional view taken along
lines 32-32 depicting the multifurcated distal section of the
catheter.
[0098] FIG. 33 is a longitudinal cross-sectional view of the
coupler depicting a guide wire slidably positioned in the dead-end
lumen of the coupler.
[0099] FIG. 34 is an elevational view and a partial longitudinal
cross-sectional view of the crimping mold assembly.
[0100] FIG. 35 is an elevational view of the catheter assembly
being advanced into the main vessel.
[0101] FIG. 36 is an elevational view of the catheter assembly in
the main vessel prior to advancement into the side branch
vessel.
[0102] FIG. 37 is an elevational view of the catheter assembly as
the over-the-wire guide wire is being advanced into the side branch
vessel.
[0103] FIG. 38 is an elevational view of the catheter assembly
positioned in the main vessel and the over-the-wire guide wire
advanced and positioned in the side branch vessel.
[0104] FIG. 39 is an elevational view of the catheter assembly
advanced so that the long balloon is in the main vessel and a
portion of the short balloon is positioned in the side branch
vessel.
[0105] FIG. 40 is an elevational view of a bifurcation depicting
the stent of the invention implanted in the main vessel and the
opening to the side branch vessel.
[0106] FIG. 41 is an elevational view of a bifurcation in which the
stent of the present invention is implanted in the main vessel, and
a second stent is implanted in the side branch vessel.
[0107] FIG. 42 is an elevational view depicting the catheter
assembly positioned in the main vessel and the over-the-wire guide
wire advancing out of the catheter.
[0108] FIG. 43 is an elevational view of the catheter assembly
positioned in the main vessel and the over-the-wire guide wire
wrapping around the coupler.
[0109] FIG. 44 is an elevational view showing the catheter assembly
positioned in the main vessel and the over-the-wire guide wire
wrapped over the coupler and positioned in the side branch
vessel.
[0110] FIG. 45 is an elevational view of the catheter assembly
advanced toward the carina or bifurcation junction but unable to
advance further due to the over-the-wire guide wire wrapped over
the coupler and/or the long tip.
[0111] FIG. 46 is an elevational view, partially in section, of a
stent delivery balloon catheter embodying features of the
invention, having secured portions along which the first and second
branches of the catheter are permanently secured together, and
having a polymeric radiopaque distal tip marker.
[0112] FIGS. 47 and 48 are enlarged, longitudinal sectional views
of the catheter of FIG. 46, taken within circles 47 and 48,
respectively.
[0113] FIG. 49 is a transverse cross section of the catheter of
FIG. 48, taken along line 49-49.
[0114] FIG. 50 is an enlarged, longitudinal sectional view of the
catheter of FIG. 46 taken within circle 50.
[0115] FIG. 51 is a transverse cross section taken along line 51-51
in FIG. 50
[0116] FIG. 52 is a longitudinal cross section of a guidewire
locking mechanism embodying features of the invention, having a
proximal fitting member and a collet member with a radially
collapsible slotted head.
[0117] FIG. 53 a longitudinal cross section of a guidewire locking
mechanism embodying features of the invention, having a fitting
with a radially collapsible slotted inner extension.
[0118] FIG. 54 is a longitudinal cross section of a guidewire
locking torque device embodying features of the invention.
[0119] FIG. 55 illustrates the balloon catheter of FIG. 46 with the
first branch of the catheter positioned within the side branch of
the blood vessel, and with the balloons 611, 612 inflated to
radially expand the stent at the blood vessel bifurcation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0120] The present invention includes a stent and stent delivery
catheter assembly and method for treating bifurcations in, for
example, the coronary arteries, veins, peripheral vessels and other
body lumens. Prior art attempts at implanting intravascular stents
in a bifurcation have proved less than satisfactory. For example,
FIGS. 1-4 depict prior art devices which include multiple stents
being implanted in both the main vessel and a side branch vessel.
In FIG. 1, a prior art "T" stent is implanted such that a first
stent is implanted in the side branch near the origin of the
bifurcation, and a second stent is implanted in the main vessel.
With this approach, portions of the side branch vessel are left
uncovered, and blood flow to the side branch vessel must
necessarily pass through the main vessel stent, causing possible
obstructions or thrombosis.
[0121] Referring to FIG. 2, three prior art stents are required to
stent the bifurcation which leaves a large gap in vessel coverage
between the stents. In FIG. 3, the prior art method includes
implanting two stents side by side, such that one stent extends
into the side branch vessel and the main vessel, and the second
stent is implanted in the main vessel. This results in a
double-barreled lumen which can present problems such as thrombosis
and turbulence in blood flow. Referring to the FIG. 4 prior art
device, a first stent is implanted in the side branch vessel, a
second stent is implanted in a proximal portion of the main vessel,
and a third stent is implanted distal to the bifurcation, thereby
leaving a small gap between the stents and resulting in an
uncovered luminal area.
[0122] All of the prior art devices depicted in FIGS. 1-4 have
various drawbacks which have been solved by the present
invention.
[0123] In treating a side branch, if a prior art stent is used in
which there is no acute angle at the proximal end of the stent to
match the angle of the bifurcation, a condition as depicted in
FIGS. 5A and 5B will occur. That is, a stent deployed in the side
branch vessel will leave a portion of the side branch vessel
exposed, or as depicted in 5B, a portion of the stent will extend
into main vessel.
[0124] The stent of the present invention can be implanted in the
main or side branch vessels to treat a number of disease
configurations at a bifurcation, but not limited to, the
following:
[0125] 1. Treatment of a parent or main vessel and the origin of
the side branch at a bifurcation with any angle associated between
the side branch and parent vessel.
[0126] 2. Treatment of a parent vessel proximal to the carina and
the side branch vessel simultaneously.
[0127] 3. Treatment of the proximal vessel extending only into the
origin of the side branch and the origin of the distal parent at
the bifurcation.
[0128] 4. Treatment of the area at the bifurcation only.
[0129] 5. The origin of an angulated posterior descending
artery.
[0130] 6. The origin of an LV extension branch just at and beyond
the crux, sparing the posterior descending artery.
[0131] 7. The origin of a diagonal from the left anterior
descending.
[0132] 8. The left anterior descending at, just proximal to, or
just distal to the diagonal origin.
[0133] 9. The origin of a marginal branch of the circumflex.
[0134] 10. The circumflex at, just proximal to, or just distal to
the marginal origin.
[0135] 11. The origin of the left anterior descending from the left
main.
[0136] 12. The origin of the circumflex from the left main.
[0137] 13. The left main at or just proximal to its
bifurcation.
[0138] 14. Any of many of the above locations in conjunction with
involvement of the bifurcation and an alternate vessel.
[0139] 15. Any bifurcated vessels within the body where
conventional stenting would be considered a therapeutic means of
treatment proximal or distal to the bifurcation.
[0140] The present invention solves the problems associated with
the prior art devices by providing a stent which adequately covers
the main branch vessel and extends partially into the side branch
vessel to cover one aspect of the origin of the side branch vessel
as well. The invention also includes a stent delivery catheter
assembly and the method of crimping the stent on the catheter and
delivering and implanting the stent in the body, especially the
coronary arteries.
The Stent Pattern
[0141] The stent pattern of the present invention is novel in that
it provides for vessel wall coverage of the main branch vessel and
at least partial coverage of the origin of the side branch vessel.
More specifically, in FIGS. 6-22, several embodiments of stent 10
are shown. Once stent 10 is implanted in the main branch vessel and
the opening to the side branch vessel, a second, conventional stent
can be implanted in the side branch vessel, essentially abutting a
portion of stent 10.
[0142] The stent 10 of the present invention has a cylindrical body
11 that includes a proximal end 12 and a distal end 13. The stent
has an outer surface 14 which contacts the vascular wall when
implanted and an inner surface 15 through which blood flows when
the stent is expanded and implanted. The stent can be described as
having connected rings 16 aligned along a common longitudinal axis
of the stent. The rings are formed of undulating portions which
include peaks 17 that are configured to be spread apart to permit
the stent to be expanded to a larger diameter or compressed tightly
toward each other to a smaller diameter when mounted on a catheter.
The rings are connected to each other by at least one link 18
between adjacent rings. Typically, there are three links that
connect adjacent rings and the links of one ring are generally
circumferentially offset from the links of an adjacent ring. While
the links 18 typically are offset as indicated, this is not always
the case.
[0143] A central opening 19 in the stent 10 allows the passage of a
balloon contained on the delivery system. The stent is to be
crimped tightly onto two separate expandable members or balloons of
a catheter. Typically, as will be described in more detail below,
the balloons on the catheter are balloons similar to a
dilatation-type balloon for conventional dilatation catheters. In
the present invention, the stent 10 is configured such that the
stent has a distal opening 20 and a proximal opening 21 that are in
axial alignment and through which a longer balloon extends. The
central opening 19 is adjacent a portal section 22 through which a
shorter balloon extends. Although the stent is crimped tightly onto
both the long and short balloons as will be described, other
delivery catheters can be used to deliver and implant the
stent.
[0144] With all of the embodiments of the stent 10 disclosed
herein, the rings 16 can be attached to each other by links 18
having various shapes, including straight links 23 or non-linear
links 24 having curved portions. The non-linear links, as shown in
FIGS. 6-13, can have undulating portions 25 that are transverse to
the longitudinal axis of the stent and act as a hinge to enhance
the flexibility of the stent.
[0145] In keeping with the invention, and with reference to FIGS.
6A and 6B, stent 10 has a cylindrical body 11 and a proximal end 12
and a distal end 13. The stent outer surface 14 contacts the vessel
when the stent is expanded, and the stent inner surface 15 provides
a smooth and unobstructed lumen through which blood flows when the
stent is expanded in a vessel. Stent 10 is comprised of multiple
rings 16 that are connected by nonlinear links 24, each having
undulating portions 25. The undulating portions 25 of the nonlinear
links 24 extend circumferentially in a direction transverse to the
longitudinal axis of the stent. In this embodiment, there are 13
rings, ring No. 1 being at the proximal end 12 of the stent while
ring No. 13 is at the distal end 13 of the stent. In this
embodiment, there are three nonlinear links 24 connecting each of
the rings 16 with the exception of two nonlinear links 24
connecting ring No. 6 to ring No. 7. This area between the sixth
and seventh ring 16 is portal section 22 which will expand into the
opening of the side branch vessel when the stent is expanded, as
will be hereinafter described.
[0146] In further keeping with the invention shown in FIGS. 6A and
6B, each of the rings 16 is made up of peaks 17 which point in the
direction of the stent proximal end 12, valleys 26 which point in
the direction of the stent distal end 13, and bar arms 27A which
connect the peaks 17 and the valleys 26. In this embodiment, bar
arms 27A have different widths in certain rings and different
lengths in certain rings in order to provide specific attributes to
stent expansion and vessel wall coverage. For example, bar arms 27B
of proximal end ring 28 (ring No. 1) are approximately the same
length and each has a width of approximately 0.09144 mm (0.0036
inch). Further, the peaks 17 and valleys 26 of proximal end ring 28
have a greater radius than the peaks and valleys of the other rings
in the stent in order to provide a more open area for gripping the
balloon when the stent is compressed onto the balloon. In further
keeping with the invention, bar arms 27C connect the peaks 17 and
valleys 26 of rings in a proximal section of the stent (ring Nos.
2-4) and several of the bar arms 27C in the portal section 22 of
the stent. The bar arms 27C are relatively longer than other of the
bar arms connecting peaks and valleys in the stent, which allows
the portal section 22 to cover more area in the opening to the side
branch vessel when the stent is expanded. The portal section rings
(rings 5-6) have a greater number of peaks and valleys than in the
proximal or distal section rings which also provides for a greater
expansion diameter. Bar arms 27D that connect peaks 17 and valleys
26 in the distal section of the stent (ring Nos. 7-13) are
relatively shorter than both the bar arms 27C connecting peaks and
valleys in the portal section 22 of the stent and the bar arms 27A
in the proximal section of the stent. Further, the width of the bar
arms in various of the rings 16 can be varied in order to increase
or decrease flexibility, with wider bar arms 27A being less
flexible than relatively narrower width bar arms. The width of bar
arms 27A in rings 16 in the proximal section (ring Nos. 2, 3 and 4)
have a width of approximately 0.09652 mm (0.0038 inch). The bar
arms 27C in the portal section 22 (ring Nos. 5 and 6) all have a
width of approximately 0.09144 mm (0.0036 inch) with the exception
of bar arms 27E which have a width of approximately 0.08128 mm
(0.0032 inch). The widths of the bar arms 27D in the rings 16 in
the distal section (ring Nos. 7-13) are approximately 0.09144 mm
(0.0036 inch). The radial thickness of the stent is constant at
approximately 0.08128 mm (0.0032 inch). The width of the various
bar arms and the radial thickness of the stent all can be varied
depending upon a particular application, and the dimensions
disclosed herein are exemplary. Further, varying the width of the
apex or crest of the peaks and valleys also affects flexibility,
with relatively narrower widths providing greater flexibility.
[0147] Other features of the invention shown in FIGS. 6A and 6B
include a greater number of peaks 17 and valleys 26 in the portal
section 22 rings than in other of the rings in the stent. For
example, ring No. 5 has eight peaks 17, ring No. 6 has eight peaks
17, proximal end ring 28 has six peaks 17, while all of the other
rings in stent 10 have six peaks 17. The greater number of peaks 17
in the portal section 22 provides for greater expansion of the
stent in that area and provides more coverage of the opening to the
side branch vessel as the portal section 22 expands into and
apposes the opening to the side branch vessel. The embodiments
shown in FIGS. 6A and 6B can be modified by increasing or
decreasing the number of rings 16 on either side of the portal
section 22. For example, for a 12 mm long stent (not shown) there
are a total of nine rings, with the portal section 22 positioned
between the sixth and seventh rings and only three rings positioned
in the distal section of the stent.
[0148] In another embodiment, as shown in FIGS. 7A and 7B, stent 10
is substantially similar to that shown in FIGS. 6A and 6B. In FIGS.
7A and 7B, there are fifteen rings 16 with the portal section 22
between ring Nos. 7 and 8, counting from the proximal end 12 toward
the distal end 13. In this embodiment, bar arms 29A of the proximal
end ring 28 have one length, and bar arms 29B of all of the other
rings 16 have substantially the same length, which is shorter than
the length of the bar arms 29A. Further, the width of bar arms 29A
is approximately 0.09144 mm (0.0036 inch) while all of the other
bar arms 29B have a width of approximately 0.08128 mm (0.0032
inch). The radial thickness of stent 10 in this embodiment is
constant throughout and is approximately 0.08128 mm (0.0032 inch).
One other distinction between the stent 10 of FIGS. 6A and 6B and
the stent 10 of FIGS. 7A and 7B is that there are a uniform number
of peaks 17 in all of the rings 16 in FIGS. 7A and 7B.
Specifically, each of the rings 16 have nine peaks 17, which
insures uniform wall coverage throughout the length of the stent.
Importantly, the nine peaks 17 in the portal section 22 provide
adequate coverage at the opening to the side branch vessel when
stent 10 is expanded in the main vessel and into the opening of the
side branch vessel as will be described herein. For even greater
expansion in the portal section 22, there can be eleven peaks 17
(not shown) which also increases wall coverage. Similar to FIGS. 6A
and 6B, the portal ring 30 in FIGS. 7A and 7B is attached to the
ring distal of the portal ring by two nonlinear links 24. The
undulating portions 25 of the nonlinear links 24 extend in opposite
directions transverse to the longitudinal axis of the stent. With
only two nonlinear links 24 connecting the portal ring to the ring
16 distal of it, this creates a larger portal section 22 which
allows the portal area to be slightly out of alignment with the
side branch vessel during delivery and still be acceptable when the
portal section 22 expands into the opening of the side branch
vessel.
[0149] In another embodiment, shown in FIG. 8A, stent 10 has a
cylindrical body 11 and a proximal end 12 and a distal end 13.
Stent 10 is shown in a flattened configuration, however, in use it
is in the form of a cylinder (not shown) and typically is formed by
laser cutting a tubular member. The stent is comprised of multiple
rings 16 that are connected by non-linear links 24, each having
undulating portions 25. The undulating portions 25 of the
non-linear links 24 extend circumferentially in a direction
transverse to the longitudinal axis of the stent. In this
embodiment, there are thirteen rings, with ring No. 1 being at the
proximal end 12 of the stent while ring No. 13 is at the distal end
13 of the stent. In this embodiment, there are three non-linear
links 24 connecting each of the rings 16 with the exception of two
non-linear links 24 connecting ring No. 6 to ring No. 7. The area
between the sixth and seventh ring is portal section 22 that will
expand into the opening into the side branch vessel when the stent
is expanded as will be hereinafter described. In keeping with the
invention as shown in FIGS. 8A and 8B, each of the rings 16 is
formed of peaks 17 which point in the direction of the stent
proximal end 12, and valleys 26 which point in the direction of the
stent distal end 13. Bar arms 31A connect the peaks 17 and the
valleys 26. In this embodiment, the undulating portion 25 of the
two links between ring Nos. 6 and 7 (the portal region 22), point
toward each other in a direction transverse to the longitudinal
axis of the stent. This provides space for bar arm 31B to be more
like bar arm 31C instead of bar arm 31D. The bar arms and struts
around bar arm 31B will expand more and move the non-linear links
24 in the portal section 22 toward the side branch vessel when the
stent is expanded. This will reduce the ring separation between
rings 6 and 7, especially when the stent is being deployed in a
curved area of the vessel. In an alternative embodiment, the
proximal end ring 28 (ring No. 1) is connected to the adjacent
cylindrical ring 16 (ring No. 2) by two non-linear links 24 having
undulating portions 25. In this embodiment, there is additional
flexibility at the proximal end of the stent which will help with
preventing strut flaring and will reduce the likelihood of the
stent catching on the guide catheter when the stent is pulled back
toward the guide catheter during delivery and implantation of the
stent.
[0150] In another embodiment as shown in FIG. 8B, stent 10 is
substantially similar to that shown and described for FIG. 8A. In
this embodiment, cylindrical ring 32 (ring No. 2 counting from the
proximal end 12 of stent 10) has substantially the same
configuration as proximal end ring 28 shown in FIG. 8A. Proximal
end ring 33 has a configuration similar to ring No. 3 of stent 10,
only the peaks 17 and the valleys 26 point in opposite directions.
Proximal end ring 33, due to its configuration having W-shaped
elements 34, provides additional support at the proximal end of the
stent for increased stent retention on the balloon portion of the
catheter and as extra retention as the catheter is pulled back into
the guiding catheter (not shown). The W-shaped elements 34 also
reduce flaring of proximal end ring 33. In this embodiment,
proximal end ring 33 is connected to the adjacent ring 32 by three
non-linear links 24 which also provide extra support at the
proximal end 12 of the stent. In this embodiment, there are fewer
rings proximal to the portal section 22 than in other designs such
as shown in FIG. 8A. This provides for more flexibility for
treating bifurcations with a short vessel length proximal to the
side branch vessel. More specifically, in this embodiment, as shown
in FIG. 8B, there are four rings proximal to the portal ring 30,
while there are seven rings distal to the portal ring 30. As with
previous embodiments, all of the rings are connected to each other
by non-linear links 24 having undulating portions 25 that extend
transverse to the longitudinal axis of the stent. The portal ring
30 is connected to the ring 16 distal of it by two non-linear links
24, while all other rings are attached to each other by three
non-linear links 24.
[0151] In another embodiment, as shown in FIG. 9, stent 10 has a
cylindrical body 11 (not shown) and a proximal end 12 and a distal
end 13. The stent of this embodiment is substantially similar to
that shown in FIGS. 6A and 6B. In this embodiment, stent 10 has
multiple rings 16 that are connected by non-linear links 24, each
of the links having undulating portions 25. The undulating portions
25 of the non-linear links 24 extend circumferentially in a
direction transverse to the longitudinal axis 35 of the stent. In
this embodiment, there are thirteen rings, ring No. 1 being at the
proximal end 12 of the stent while ring No. 13 is at the distal end
13 of the stent. Further, there are three non-linear links 24
connecting each of the rings 16 with the exception of two
non-linear links 24 connecting ring No. 6 to ring No. 7. The area
between the sixth and seventh ring 16 is portal section 22 that
expands into the opening of the side branch vessel when the stent
is expanded, as will be further described herein. In further
keeping with the invention shown in FIG. 9, each of the rings 16 is
made up of peaks 17 which point in the direction of stent proximal
end 12, valleys 26 which point in the direction of the stent distal
end 13, and bar arms 36 which connect the peaks 17 and the valley
26. In this embodiment, proximal section 37 includes ring Nos. 1-4
and distal section 38 includes ring Nos. 7-13. Portal ring 39A and
39B represent ring Nos. 5 and 6, respectively. Portal rings 39A and
39B have eight peaks, while all of the rings in the proximal
section 37 and the distal section 38 have six peaks. The rings in
the proximal section 37 have larger expansion diameters than the
rings 16 in the distal section 38. The greater expansion diameters
in the proximal section 37 rings will accommodate any
post-dilatation using a well known kissing-balloon technique.
[0152] In another embodiment, shown in FIG. 10, stent 10 includes
rings 16 comprised of first rings 40 and second rings 41. First
rings 40 include first peaks 42 and first valleys 43 while second
rings 41 include second peaks 44 and second valleys 45. In this
embodiment, first peaks 42 of first rings 40 point in a direction
toward distal end 13 while second peaks 44 of second rings 41 point
toward proximal end 12 of stent 10. Stated differently, stent 10
has thirteen rings, ring No. 1 being at the proximal end 12 and
ring No. 12 being at distal end 13 of the stent. Ring Nos. 1
through 4 include first rings 40, while ring Nos. 5 through 12
include second rings 41. In this configuration the W-shaped member
46 at the proximal end 12 of the stent can include two or three
non-linear links 24 which allows the flexibility of the proximal
end of the stent to be modified to allow a smooth guide pull-back.
In the embodiment shown in FIG. 10, there are three non-linear
links 24 connecting adjacent links to each other with the exception
of the connection between ring Nos. 5 and 6, which have two
non-linear links 24 connecting the two rings. The area between ring
Nos. 5 and 6 is portal region 47 which is configured to expand into
the opening of a side branch vessel when the stent is expanded and
implanted in a bifurcated vessel. In further keeping with the
invention, non-linear links 55 are substantially longer than
non-linear links 24 and are configured to allow ring No. 5
(counting from proximal end 12) to expand and extend further into
the side branch vessel in order to provide more coverage at the
opening to the side branch vessel. For example, as the stent
expands during implantation, the center line of most of the rings
stay in the same position. With respect to ring Nos. 4 and 5, as
the stent expands W-shaped members 49 and 50 stay approximately the
same distance apart which then forces W-shaped member 49 into the
side branch vessel along with peak 51. At the same time, non-linear
link 52 helps keep the rings from being pushed away from the
opening to the side branch vessel. Non-linear link 53 also exhibits
similar behavior, but it may not necessarily be aligned with the
opening to the side branch vessel and have as significant an impact
as does non-linear link 52. The undulating portion 54 of non-linear
link 55 adds flexibility to W-shaped members 49 and 50, however, it
may reduce the extension of the W-shaped member 49 and peak 51 into
the side-branch vessel. As an alternative embodiment, non-linear
link 55 can be a straight link which would reduce flexibility, but
allow the W-shaped member 49 and peak 51 to extend even further
into the side branch vessel.
[0153] In another embodiment, as shown in FIG. 11, stent 10 is
substantially the same as the stent depicted in FIG. 10 with two
notable exceptions. First, linear links 56 connect the fourth ring
(from the proximal end 12) to the No. 5 ring. Secondly, peak 57
extends in a proximal direction toward proximal end 12 since there
is no longer an undulating portion from a non-linear link to
interfere with peak 57 when the stent is compressed to its crimped
state prior to deployment. By replacing the non-linear link in FIG.
10 with linear links 56 in FIG. 11, this increases the axial
stiffness in the portal region 47 and the force that moves W-shaped
member 58 and 59 apart is maximized. This also enhances protrusion
of peak 60 and W-shaped member 58 into the opening of the side
branch vessel. While some flexibility is sacrificed in delivery and
deployment, the opening to the side branch vessel is adequately
covered. By removing the undulating portion of linear links 56
which connect ring Nos. 4 and 5, additional space is created in the
pattern. Moving peak 57 proximally toward the proximal end 12
allows the portal region 47 to open further due to the increased
bar arm length 63. In this case, peak 57 has been moved proximally
to extend beyond peak 61 so that ring Nos. 4 and 5 partially
overlap, at least in this area. Peaks 57 and 62 can be adjusted in
position to alter the opening characteristics of these rings by the
portal region 47.
[0154] In another embodiment, shown in FIG. 12, stent 10 is similar
to the configuration and pattern of the stent of FIG. 11. In this
embodiment, valley 64 and valley 65 as well as peaks 66 and 67 all
have been moved distally toward distal end 13. Each of valleys
64/65 and peaks 66,67 have longer bar arms 68 which will move and
extend ring Nos. 4 and 5 (counting from the proximal end 12)
further into the opening to the side branch vessel. In this
embodiment, ring Nos. 5 and 6 overlap at the portal region 47,
however, this does not mean that the various valleys and peaks
overlap or cross over each other. In other words, when the stent is
mounted on the side branch balloon and the main vessel balloon,
valley 64 is mounted on the side branch balloon while peak 69 is on
the main vessel balloon which is under the side branch balloon,
therefore there is no interference of overlap when the stent is in
a crimped configuration. Further, peaks 66 and 67 have been moved
toward each other which allows ring No. 4 to open further.
[0155] In another embodiment, shown in FIG. 13, stent 10 is similar
to the stent configuration of FIG. 12. In FIG. 13, linear links 70
connect ring No. 3 to ring No. 4 (counting from proximal end 12 to
distal end 13), whereas in FIG. 12 these links were non-linear
links having undulating portions. As a result, there is a larger
reaction force from the expansion of ring 3 toward ring No. 4 so
that point 71 on linear link 70 provides an anchor for point 72 in
order to limit any proximal movement to proximal end 12. With point
72 now more stable, point 73 should move more distally toward
distal end 13 when the stent is expanded. This movement also causes
points 74 and 75 to move more into the opening of the side branch
vessel, and even partially into the side branch vessel.
[0156] The present invention stent extends only into the ostium of
the side branch vessel while the main body of the stent scaffolds
the main branch vessel and the cornea of the bifurcation, but the
stent provides no scaffolding into the side branch vessel. In order
to stent the side branch vessel, a second stent is implanted so
that the proximal end of the second stent abuts the distal end of
the portal region of the bifurcated stent. Under fluoroscopy, it is
often difficult to align the proximal end of the second stent with
the distal end of the portal region of the bifurcated stent.
Accordingly, in one embodiment of the present invention, radiopaque
markers are positioned to assist in the alignment of the second
stent in the side branch vessel so that it abuts the distal end of
the portal region of the bifurcated stent and yet the struts of the
two stents do not overlap or result in a gap between the stents. In
one embodiment, as shown in FIG. 14, bifurcated stent 80 has a
proximal end 81 and a distal end 82. A portal region 83 extends
into the ostium of the side branch vessel, yet does not extend into
the side branch vessel to provide scaffolding to the vessel. The
portal region distal end 84 extends only into the ostium of the
side branch vessel. In order to accurately deploy and implant
second stent 85 in the side branch vessel, a pair of proximal
radiopaque markers 86 are positioned approximately 180.degree.
apart on proximal end 81 of the bifurcated stent 80. The second
stent 85 is delivered by delivery catheter 87 which has a
radiopaque marker collar 88 positioned on the catheter shaft 89 of
delivery catheter 87. After the bifurcated stent 80 has been
implanted, delivery catheter 87 passes through the expanded
bifurcated stent 80 so that the second stent 85 can be advanced
through the portal region 83 and into the side branch vessel.
During delivery of second stent 85 to the side branch vessel, the
radiopaque marker collar 88 will come into alignment with the
proximal radiopaque markers 86 positioned at the proximal end 81 of
the bifurcated stent 80. When the radiopaque markers 86 and 88 come
into alignment, the proximal end 90 of the second stent will be in
alignment with the distal end 84 of the portal region 83. At that
point, the second stent 85 can be expanded and implanted in the
side branch vessel so that the proximal end 90 abuts the distal end
84 of the portal region 83.
[0157] In another embodiment, as shown in FIG. 15, the bifurcated
stent 80 has a proximal end 81 and a distal end 82 with portal
region 83 extending into the ostium of the side branch vessel. The
distal end 84 of the portal region 83 has a radiopaque marker 91
that is visible under fluoroscopy. In this embodiment, second stent
85 is delivered by delivery catheter 87 which has radiopaque marker
collar 91 positioned just proximal of the proximal end 90 of the
second stent 85. When the second stent 85 is being delivered to the
side branch vessel, the radiopaque marker collar 91 comes into
alignment with radiopaque marker 92 positioned at the distal end 84
of portal region 83. Once radiopaque markers 91 and 92 are aligned,
the second stent 85 is properly positioned in the side branch
vessel where it can be expanded and implanted. The proximal end 90
of the second stent 85 will abut the distal end 84 of the portal
region 83. Similarly, as shown in FIG. 16, a second radiopaque
marker 92 is positioned on the distal end 84 of portal region 83 to
assist in aligning the second stent 85 in the side branch vessel.
With two radiopaque markers 92, any errors due to parallax based on
an angiographic view under fluoroscopy are eliminated.
[0158] In another embodiment used for aligning the side branch
stent, as shown in FIG. 17, the bifurcated stent 80 has proximal
end 81 and distal end 82 with a portal region 83 extending into the
ostium of the side branch vessel. In this embodiment, radiopaque
markers 92 are positioned on the distal end 84 of portal region 83.
Second stent 85 has a radiopaque marker 93 on the proximal end 90
of the second stent 85. As the delivery catheter 87 advances the
second stent 85 into the side branch vessel, the radiopaque marker
93 located on the proximal end 90 of the second stent 85 comes into
alignment with the radiopaque markers 92 positioned on the distal
end 84 of the portal region 83. At that point, the proximal end 90
of the second stent 85 is properly aligned with the distal end 84
of the portal region so that the second stent 85 can be expanded
and implanted in the side branch vessel and the proximal end 90 of
the second stent 85 will abut distal end 84 of the portal region
83.
[0159] In one aspect of the invention, plaque or lesions can
accumulate at various locations in and around a bifurcated vessel.
For example, in FIGS. 18A-18D, plaque or lesions are shown in black
as representing areas where plaque can accumulate. Various prior
art stents have been used to treat plaque in and around the
bifurcated vessel with varying results. Often, the prior art stents
are unable to fully cover the bifurcated vessel area to adequately
scaffold the bifurcated vessel. In one embodiment of the present
invention, as shown in FIGS. 18E, 18H, and 19-21, stent 94 has a
number of radiopaque markers 95 that are positioned to identify a
distal portal region 96, a mid-portal region 97, and a proximal
portal region 98. In these embodiments, stent 94 can be customized
to allow any of the distal, mid and proximal portal regions
96,97,98 to be used to align with and partially expand into the
opening of the side branch vessel, depending upon the location of
the side branch vessel relative to the main vessel, and the
accumulation of plaque as previously described. Thus, and as will
be hereinafter described, the balloon portion of a catheter extends
through stent 94, and a second balloon extends through any of the
distal portal region 96, mid-portal region 97, or proximal portal
region 98. Typically, the physician would determine through
fluoroscopic imaging the portal region that would best fit the
anatomy of the patient based on the location of the bifurcated
vessel, and the plaque or lesions to be treated. The radiopaque
markers 95 on stent 94 will be visible under fluoroscopy or other
imaging procedures in order to properly align any of the distal
portal region 96, mid-portal region 97, or proximal portal region
98 with the opening to the side branch vessel of the bifurcation.
Typically, radiopaque markers 95 can be platinum iridium, tungsten,
or silver, and be coated onto the struts of stent 94 in a known
manner.
[0160] The radiopaque markers 95 of stent 94 can be formed in
numerous ways in order to identify the portal regions on the stent.
For example, as shown in FIG. 22, a high percentage tungsten
material is loaded into a polymer to form a polymer coating which
is then applied to the struts of the stents to form radiopaque
markers 95. A high percentage, typically greater than 60% tungsten,
is loaded into a polymer such as PEBAX, which is then formed or
coated onto the struts to form the radiopaque markers. The tungsten
loaded polymers must be able to expand so that as the stent is
expanded, there is no adverse effect on the ability of the stent to
expand or an adverse affect on the integrity of the coating. Other
metals can be used in place of tungsten to be loaded into the
polymer, such as platinum, platinum iridium, and silver.
[0161] Each embodiment of the stent 10 also can have rings 16 and
links 18 that have variable thickness struts, at various points in
order to increase the radial strength of the stent, provide higher
radiopacity so that the stent is more visible under fluoroscopy,
and enhance flexibility in the portions where the stent has the
thinnest struts. The stent also can have variable width struts to
vary flexibility, maximize vessel wall coverage at specific points,
or to enhance the stent radiopacity. The variable thickness struts
or variable width struts, which may be more radiopaque than other
struts, can be positioned along the stent to help the physician
position the stent during delivery and implantation in the
bifurcated vessel.
[0162] The stent 10 can be formed in a conventional manner
typically by laser cutting a tubular member or by laser cutting a
pattern into a flat sheet, rolling it into a cylindrical body, and
laser welding a longitudinal seam along the longitudinal edges of
the stent. The stent can also be fabricated using conventional
lithographic and etching techniques where a mask is applied to a
tube or flat sheet. The mask is in the shape of the final stent
pattern and is used for the purpose of protecting the tubing during
a chemical etching process which removes material from unwanted
areas. Electro-discharge machining (EDM) can also be used for
fabricating the stent, where a mold is made in the negative shape
of the stent and is used to remove unwanted material by use of an
electric discharge. The method of making stents using laser cutting
processes or the other described processes are well known. The
stent of the invention typically is made from a metal alloy and
includes any of stainless steel, titanium, nickel-titanium (NiTi or
nitinol of the shape memory or superelastic types), tantalum,
cobalt-chromium, cobalt-chromium-vanadium,
cobalt-chromium-tungsten, gold, silver, platinum, platinum-iridium
or any combination of the foregoing metals and metal alloys. Any of
the listed metals and metal alloys can be coated with a polymer
containing fluorine-19 (19F) used as a marker which is visible
under MRI. Portions of the stent, for example some of the links,
can be formed of a polymer impregnated with 19F so that the stent
is visible under MRI. Other compounds also are known in the art to
be visible under MRI and also can be used in combination with the
disclosed metal stent of the invention.
[0163] The stent of the invention also can be coated with a drug or
therapeutic agent to assist in repair of the bifurcated vessel and
may be useful, for example, in reducing the likelihood of the
development of restenosis. Further, it is well known that the stent
(usually made from a metal) may require a primer material coating
to provide a substrate on which a drug or therapeutic agent is
coated since some drugs and therapeutic agents do not readily
adhere to a metallic surface. The drug or therapeutic agent can be
combined with a coating or other medium used for controlled release
rates of the drug or therapeutic agent. Examples of therapeutic
agents that are available as stent coatings include rapamycin,
ererolimus clobetasol, actinomycin D (ActD), or derivatives and
analogs thereof. ActD is manufactured by Sigma-Aldrich, 1001 West
Saint Paul Avenue, Milwaukee, Wis. 53233, or COSMEGEN, available
from Merck. Synonyms of actinopmycin D include dactinomycin,
actinomycin IV, actinomycin l1, actinomycin X1, and actinomycin C1.
Examples of agents include other antiproliferative substances as
well as antineoplastic, antinflammatory, antiplatelet,
anticoagulant, antifibrin, antithomobin, antimitotic, antibiotic,
and antioxidant substances. Examples of antineoplastics include
taxol (paclitaxel and docetaxel). Examples of antiplatelets,
anticoagulants, antifibrins, and antithrombins include sodium
heparin, low molecular weight heparin, hirudin, argatroban,
forskolin, vapiprost, prostacyclin and prostacyclin analogs,
dextran, D-phe-pro-arg-chloromethylketone (synthetic antithrombin),
dipyridamole, glycoprotein, llb/llla platelet membrane receptor
antagonist, recombinant hirudin, thrombin inhibitor (available from
Biogen), and 7E-3B.RTM. (an antiplatelet drug from Centocore).
Examples of antimitotic agents include methotrexate, azathioprine,
vincristine, vinblastine, fluorouracil, adriamycin, and mutamycin.
Examples of cytostatic or antiproliferative agents include
angiopeptin (a somatostatin analog from Ibsen), angiotensin
converting enzyme inhibitors such as Captopril (available from
Squibb), Cilazapril (available from Hoffman-LaRoche), or Lisinopril
(available from Merck); calcium channel blockers (such as
Nifedipine), colchicine fibroblast growth factor (FGF) antagonists,
fish oil (omega 3-fatty acid), histamine antagonist, Lovastatin (an
inhibitor of HMG-CoA reductase, a cholesterol lowering drug from
Merck), monoclonal antibodies (such as PDGF receptors),
nitroprusside, phosphodiesterase inhibitors, prostaglandin
inhibitor (available from Glazo), Seramin (a PDGF antagonist),
serotonin blockers, steroids, thioprotease inhibitors,
triazolopyrimidine (a PDGF antagonist), and nitric oxide. Other
therapeutic substances or agents which may be appropriate include
alpha-interferon, genetically engineered epithelial cells, and
dexamethasone.
[0164] It should be understood that any reference in the
specification or claims to a drug or therapeutic agent being coated
on the stent is meant that one or more layers can be coated either
directly on the stent or onto a primer material on the stent to
which the drug or therapeutic agent readily attaches.
The Stent Delivery Catheter Assembly
[0165] Any of the stents of the present invention can be delivered
by any of the catheter assemblies disclosed herein. As shown in
FIGS. 23-28A, the stent 10 is mounted on catheter assembly 101
which has a distal end 102 and a proximal end 103. The catheter
assembly includes a proximal shaft 104 which has a proximal shaft
over-the-wire (OTW) guide wire lumen 105 and a proximal shaft
inflation lumen 106 which extends therethrough. The proximal shaft
OTW guide wire lumen is sized for slidably receiving an OTW guide
wire. The inflation lumen extends from the catheter assembly
proximal end where an indeflator or similar device is attached in
order to inject inflation fluid to expand balloons or expandable
members as will be herein described. The catheter assembly also
includes a mid-shaft 107 having a mid-shaft OTW guide wire lumen
108 and a mid-shaft rapid-exchange (Rx) guide wire lumen 109. The
proximal shaft OTW guide wire lumen 105 is in alignment with and an
extension of the mid-shaft OTW guide wire lumen 108 for slidably
receiving an OTW guide wire. The mid-shaft also includes a
mid-shaft inflation lumen 110 which is in fluid communication with
the proximal shaft inflation lumen 106 for the purpose of providing
inflation fluid to the expandable balloons. There is an Rx proximal
port or exit notch 115 positioned on the mid-shaft such that the Rx
proximal port is substantially closer to the distal end 102 of the
catheter assembly than to the proximal end 103 of the catheter
assembly. While the location of the Rx proximal port may vary for a
particular application, typically the port would be between 10 and
50 cm from the catheter assembly distal end 102. The Rx proximal
port or exit notch provides an opening through which an Rx guide
wire 116 exits the catheter and which provides the rapid exchange
feature characteristic of such Rx catheters. The Rx port 115 enters
the mid-shaft such that it is in communication with the mid-shaft
Rx guide wire lumen 109.
[0166] The catheter assembly 101 also includes a distal Rx shaft
111 that extends from the distal end of the mid-shaft and which
includes an Rx shaft Rx guide wire lumen 112, to the proximal end
of the inner member 111A inside balloon 117. The distal Rx shaft
111 also contains an Rx shaft inflation lumen 114. The Rx shaft Rx
guide wire lumen 112 is in alignment with the Rx guide wire lumen
109 for the purposes of slidably carrying the Rx guide wire 116.
The Rx shaft inflation lumen 114 is in fluid communication with the
mid-shaft inflation lumen 110 for the purposes of carrying
inflation fluid to the long expandable member or long balloon.
[0167] The catheter assembly also contains an Rx inner member 111A
that extends from the distal end of the distal Rx shaft 111 to the
Rx shaft distal port 113. The Rx inner member 111A contains an Rx
guide wire lumen 111B. The Rx inner member guide wire lumen 111B is
in alignment with the Rx shaft Rx guide wire lumen 112 for the
purpose of slidably carrying the Rx guide wire 116. The Rx guide
wire will extend through the Rx proximal port 115 and be carried
through Rx guide wire lumen 109 and Rx shaft Rx guide wire lumen
112, and through Rx guide wire lumen 111B and exit the distal end
of the catheter assembly at Rx shaft distal port 113.
[0168] The catheter assembly further includes a long balloon 117
positioned adjacent the distal end of the catheter assembly and a
distal tip 118 at the distal end of the Rx shaft. Further, a
coupler 119 is associated with distal Rx shaft 111 such that the Rx
shaft Rx guide wire lumen 112 extends through the coupler, with the
distal port 113 being positioned at the distal end of the coupler.
The coupler has an Rx guide wire lumen 120 that is an extension of
and in alignment with Rx lumen 111B. The coupler 119 further
includes a blind lumen 121 for receiving and carrying an OTW guide
wire (or joining mandrel) 125. The blind lumen includes a blind
lumen port 122 for receiving the distal end of the OTW guide wire
(or joining mandrel) 125 and a dead-end lumen 124 positioned at the
coupler distal end 123. The coupler blind lumen 121 will carry the
distal end of a guide wire (either the distal end of the OTW guide
wire (or joining mandrel) 125 or an Rx guide wire (or joining
mandrel) 116 as will be further described herein) during delivery
of the catheter assembly through the vascular system and to the
area of a bifurcation. The blind lumen is approximately 3 to 20 mm
long, however, the blind lumen can vary in length and diameter to
achieve a particular application or to accommodate different sized
guide wires having different diameters. Since the coupler moves
axially relative to the shaft it is not connected to, the guide
wire that resides in the blind lumen 121 of the coupler slides
axially relative to the coupler during delivery of the catheter
assembly through the vascular system and tortuous anatomy so that,
additional flexibility is imported to the tips making it easier to
track through tortuous circuitry. A distance "A" should be
maintained between the distal end 126 of the OTW guide wire 125 and
the dead end 124 of the blind lumen. The distance "A" can range
from approximately 0.5 to 5.0 mm, however, this range may vary to
suit a particular application. Preferably, distance "A" should be
about 0.5 mm to about 2.0 mm.
[0169] The catheter assembly 101 also includes an OTW shaft 128
which extends from the distal end of mid-shaft 107. The OTW shaft
carries a short balloon 129 that is intended to be shorter than
long balloon 117 and positioned substantially adjacent to the long
balloon. The OTW shaft 128 also includes an OTW lumen 130 that is
in alignment with the mid-shaft OTW guide wire lumen 108 and
proximal shaft OTW guide wire lumen 105. Thus, an OTW lumen extends
from one end of the catheter assembly to the other and extends
through the OTW shaft 128. An OTW shaft distal port 131 is at the
distal end of the OTW lumen 130 and the OTW shaft 128 also includes
an OTW shaft inflation lumen 132. Inflation lumen 132 is in
alignment and fluid communication with inflation lumens 110 and 106
for the purpose of providing inflation fluid to the long balloon
117 and the short balloon 129. In this particular embodiment, an
OTW guide wire 125 would extend from the proximal end 103 of the
catheter assembly and through proximal shaft OTW guide wire lumen
105, mid-shaft OTW guide wire lumen 108, OTW lumen 130 and out
distal port 131 where it would extend into the coupler 119, and
more specifically into blind lumen 121 through blind lumen port
122.
[0170] In order for the catheter assembly 101 to smoothly track and
advance through tortuous vessels, it is preferred that the OTW
lumen 130 be substantially aligned with the blind lumen 121 of
coupler 119. In other words, as the OTW guide wire extends out of
the OTW lumen 130, it should be aligned without bending more than
about .+-.10.degree. so that it extends fairly straight into the
coupler blind lumen 121. If the OTW lumen 120 and the coupler blind
lumen 121 are not substantially aligned, the pushability and the
trackability of the distal end of the catheter assembly may be
compromised and the physician may feel resistance as the catheter
assembly is advanced through tortuous vessels, such as the coronary
arteries.
[0171] In an alternative embodiment, as will be explained more
fully herein, a mandrel (stainless steel or nickel titanium wire is
preferred) resides in the OTW guide wire lumens 105,108,130, and
extends into blind lumen 121. The mandrel is used in place of an
OTW guide wire until the catheter assembly has been positioned near
the bifurcated vessel, at which time the mandrel can be withdrawn
from the vascular system and the OTW guide wire advanced through
the OTW guide wire lumens to gain access to the side branch vessel.
This will be described more fully in the section related to
delivering and implanting the stent.
[0172] The catheter assembly 101 of the present invention can be
dimensioned for various applications in a patient's vascular
system. Such dimensions typically are well known in the art and can
vary, for example, for various vessels being treated such as the
coronary arteries, peripheral arteries, the carotid arteries, and
the like. By way of example, the overall length of the catheter
assembly for treating the coronary arteries typically is
approximately 135 to 150 cm. Further, for stent delivery in the
coronary arteries at a bifurcated vessel, the working surface or
the stent carrying surface of the long balloon 117 can be about
18.5 mm for use with an 18 mm-long stent. The short balloon 129
typically will be about 6 to 9 mm, depending on the type of trap
door stent 20 that is being implanted. The lengths of the various
shafts, including proximal shaft 104, mid-shaft 107, distal Rx
shaft 111, and OTW shaft 128 are a matter of choice and can be
varied to suit a particular application.
[0173] As shown in FIG. 28A, radiopaque markers 135 are placed on
the catheter assembly to help the physician identify the location
of the distal end of the catheter in relation to the target area
for stent implantation. While the location of the radiopaque
markers is a matter of choice, preferably the long balloon 117 will
have three radiopaque markers on the inner shaft of the guide wire
lumen 112 and the short balloon 129 will have one radiopaque marker
on the inner member of the OTW guide wire lumen 130. Preferably,
the middle radiopaque marker on the inner shaft of the long balloon
is aligned with the opening of the trap door. One or more of the
radiopaque markers may coincide with the alignment of the stent on
the balloons which will be described more fully herein.
[0174] FIG. 29 illustrates another embodiment of a bifurcated
catheter 140 which embodies features of the invention. As with
catheter 101, the bifurcated catheter 140 can be used for a variety
of procedures such as dilatation, drug delivery, and delivering and
deploying a stent, including a stent of the invention, in a body
lumen. Bifurcated catheter 140 generally comprises an elongated
shaft 142 having a proximal shaft section 144 with a first
inflation lumen 146, and a multifurcated distal shaft section 148
with a first branch 150 and at least a second branch 152. The first
branch 150 has a second inflation lumen 154 within at least a
portion thereof in fluid communication with the first inflation
lumen 146 and the second branch 152 has a third inflation lumen 156
within at least a portion thereof in fluid communication with the
first inflation lumen 146. An intermediate shaft section 158 joins
the proximal and distal sections together and defines a fourth
inflation lumen 160 in fluid communication with the first, second,
and third inflation lumens 146/154/156. A joining wire lumen 162
extends within the proximal section, the intermediate section, and
the first branch 150 of the multifurcated distal section 148. The
guide wire lumen 164 extends within the intermediate section 158
and the second branch 152 of the multifurcated distal section 148.
A guide wire lumen 164 extends within the intermediate section 158
and the second branch 152 of the multifurcated distal section 148.
A first balloon 166 is on the first branch 150 and a second balloon
168 is on the second branch 152, with interiors in fluid
communication with the inflation lumens. An adapter 169 on the
proximal end of the catheter is configured to direct inflation
fluid into the inflation lumens and to provide access to joining
wire lumen 162. A coupler 170 on the second branch, distal to the
second balloon 168, is configured for releasably coupling the first
and second branches 150/152 together to form a coupled
configuration, as discussed in more detail below. The bifurcated
catheter 140 is illustrated in the coupled configuration in FIG.
29.
[0175] In the embodiment illustrated in FIG. 29, the joining wire
lumen 162 is defined by a first inner tubular member 172, and the
guide wire lumen 164 is defined by a second inner tubular member
174. In a presently preferred embodiment, the first inner tubular
member 172 is formed of a single tubular member, which may comprise
one or more layers as is conventionally known in the art. However,
in alternative embodiments, the first inner tubular member 172 may
be formed of separate longitudinal members joined together, end to
end, along the length of the first inner tubular member 172.
Similarly, the second inner tubular member 174 is preferably a
single or multi-layered, single tubular member, although a
plurality of separate members may be joined together to form the
second inner tubular member 174.
[0176] The present invention provides a radiopaque marker for use
on a variety of devices that is flexible, highly radiopaque and is
easily attachable to such devices by melt bonding. These properties
allow markers to be of minimal thickness and thereby minimize the
effect the marker has on the overall profile and stiffness of the
device to which it is to be attached.
[0177] In order to achieve the high fill ratios that are necessary
to attain the desired radiopacity and in order to do so without
compromising the compoundability and workability of the polymeric
material nor its ultimate strength and flexibility, a number of
different parameters have been found to be of importance. More
specifically, both the particle shape and particle size of the
radiopaque agent must be carefully controlled while the inclusion
of a wetting agent such as MA-g-PO in the polymer blend is
critical. An antioxidant may additionally be included in an effort
to reduce the adverse effect the high processing temperatures and
shear stresses may have on polymer properties.
[0178] A number of polymeric materials are well suited for use in
the manufacture of the markers of the present invention. The
material preferably comprises a low durometer polymer in order to
render the marker sufficiently flexible so as not to impair the
flexibility of the underlying medical device component to which the
finished marker is to be attached. Additionally, in one embodiment,
the polymer is preferably compatible with the polymeric material of
which the component is constructed so as to allow the marker to be
melt bonded in place. For example, in one embodiment, the polymeric
marker and at least an outer layer of the catheter shaft are formed
of the same class of the polymers (e.g., polyamides) so that they
are melt bondable together. In another embodiment, the polymeric
markers are installed on a dissimilar class of polymeric substrate,
and are retained in position by adhesion or dimensional
interference. The polymer must also impart sufficient strength and
ductility to the marker compound so as to facilitate its extrusion
and forming into a marker, its subsequent handling and attachment
to a medical device and preservation of the marker's integrity as
the medical device is flexed and manipulated during use. Examples
of such polymers include but are not limited to polyamide
copolymers like Pebax, polyetherurethanes like Pellethane,
polyester copolymers like Hytrel, olefin derived copolymers,
natural and synthetic rubbers like silicone and Santoprene,
thermoplastic elastomers like Kraton and specialty polymers like
EVA and ionomers, etc. as well as alloys thereof. A Shore durometer
of not greater than about 63D to about 25D is preferred. The
preferred polymer for use in the manufacture of a marker in
accordance with the present invention is polyether block polyamide
copolymer (PEBAX), with a Shore durometer of about 40D. However,
other classes of polymers allowing for lower durometers may be used
in the radiopaque markers, such as polyurethanes, which may provide
greater flexibility.
[0179] A number of different metals are well known to be
radiographically dense and can be used in a pure or alloyed form to
mark medical devices so as to render them visible under
fluoroscopic inspection. Commonly used metals include but are not
limited to platinum, gold, iridium, palladium, rhenium and rhodium.
Less expensive radiopaque agents include tungsten, tantalum, silver
and tin, of which tungsten is most preferred for use in the markers
of the present invention.
[0180] The control of particle size has been found to be of
critical importance for achieving the desired ultra high fill
ratios. While efforts to increase fill ratios have previously
utilized small average particle sizes (1 micron or less) so as to
minimize the ratio of particle size to as-extruded wall thickness,
it has been found that higher fill percentages can be realized with
the use of somewhat larger average particles sizes. It is desirable
in the formulation of high fill ratio compounds to have the
following attribute: 1) uniform distribution of the filler
particles, and 2) continuity of the surrounding polymer matrix, and
3) sufficient spacing between filler particles so that the polymer
matrix provides ductility to the bulk mixture to impart
processability in both the solid and molten state.
[0181] The use of larger average particle sizes results in greater
spacing between filler particles at a given percentage, thus
maintaining processability during compounding and especially
subsequent extrusion coating. The upper limit of average particle
size is determined by the wall thickness of the coating and the
degree of non-uniformity tolerable (i.e., surface defects). It has
been found that a particle size distribution having an average
particle size range of at least 2 microns to 10 microns and a
maximum particle size of about 20 microns yields the desired fill
ratio and provides for a smooth surface in the marker made
therefrom.
[0182] The control of particle shape has also been found to be of
critical importance for achieving the desired ultra high fill
ratios. Discrete particles of equiaxed shape have been found to be
especially effective, as individual particles of irregular shape,
including agglomerations of multiple particles, have been found to
adversely impact the surface, and thus, the maximum fill ratio that
is attainable.
[0183] It has also been found that the process by which certain
metal powders are produced has a profound effect on the shape of
the individual particles. In the case of metallic tungsten, the
powders may be formed by the reduction of powdered oxides through
either "rotary," "pusher" or "atomization" processing. Of these
processes, "rotary" processing has been found to yield the least
desirable shape and size distribution as partial sintering causes
coarse agglomerates to be formed which do not break up during
compounding or extrusion and thus adversely effect the marker
manufactured therefrom. Atomized powders have been reprocessed by
melting and resolidifying "rotary" or "pusher" processed powders
and result in generally equiaxed, discrete particles which are
suitable for use in the present invention. "Pusher" processed
powders are preferred due to their low cost and discrete, uniformly
shaped particles.
[0184] In order for the polymer to most effectively encapsulate
individual radiopaque particles, it is necessary for a low-energy
interface to exist between such particles and the polymer so as to
enable the polymer to "wet" the surface of the particles. The
materials should have similar surface energies to be compatible.
For materials which do not naturally have similar surface energies,
compatibility can be promoted by generating a similar surface
energy interface, i.e., a surface energy interface which is
intermediate between the natural surface energies of the materials.
Certain additives such as surfactants and coupling agents may serve
as wetting agents and adhesion promoters for polymer/metal
combinations that are not naturally compatible. It has been found
that additives containing maleic anhydride grafted to a polyolefin
backbone provide a significant benefit in this regard wherein
materials commercially available as Lotader 8200 (having LLDPE
Backbone) and Licomont AR504 (having PP backbone) were found to be
particularly effective for use with tungsten/Pebax combinations.
Emerging extrusions were found to be less susceptible to breakage,
and the melt viscosity during compounding was lower as was
manifested by a reduction in torque exerted during the extrusion
process. The use of such additives allowed compounds with higher
fill ratios to be successfully produced.
[0185] The inclusion of an antioxidant in the marker composition
has also been found to be of benefit. Commercially available
antioxidants such as Irganox B225 or Irganox 1010, have been found
to minimize degradation (i.e., reduction in molecular weight) of
the polymer matrix as it is exposed to the multiple heat and shear
histories associated with the compounding, extrusion, and bonding
processes.
[0186] The compound used for the manufacture of the marker of the
present invention is preferably made by first blending the polymer
resin and wetting agent, and optionally, an antioxidant such as by
tumble mixing after which such blend is introduced into a
twin-screw extruder via a primary feeder. The feed rate is
carefully controlled in terms of mass flow rate to ensure that a
precise fill ratio is achieved upon subsequent combination with the
radiopaque agent. The heat that the materials are subjected as they
are conveyed through the extruder causes the polymer to melt to
thereby facilitate thorough homogenization of all of the
ingredients. The radiopaque agent powder, selected for its uniform
particle shape and controlled particle size distribution as
described above is subsequently introduced into the melt stream via
a secondary feeder, again at a carefully controlled mass flow rate
so as to achieve the target fill ratio. The solid powder, molten
polymer and additives are homogenized as they are conveyed
downstream and discharged through a die as molten strands which are
cooled in water and subsequently pelletized. The preferred
extrusion equipment employs two independent feeders as introduction
of all components through a single primary feeder would require
significantly higher machine torques and result in excessive screw
and barrel wear. The powder feeder is preferentially operated in
tandem with a sidefeeder device, which in turn conveys the powder
through a sealed main barrel port directly into the melt stream. A
preferred composition comprises a fill ratio of at least 90.8
weight percent of tungsten (H.C. Starck's Kulite HC600s, HC180s and
KMP-103JP) to Pebax 40D. A maleic anhydride source in the form of
Licomont AR504 is initially added to the polymer resin at the rate
of approximately 3 pphr while an antioxidant in the form of Ciba
Geigy Irganox B225 at the rate of approximately 2 pphr (parts per
hundred relative to the resin). The temperature to which materials
are subjected to in the extruder is about 221.degree. C.
[0187] Once the marker material has been compounded, the marker can
be fabricated in suitable dimensions by an extrusion coating
process. While free extrusion is possible, this method is
problematic due to the high fill ratios of the polymeric materials.
Extrusion onto a continuous length of beading has been found to
lend the necessary support for the molten extrudate to prevent
breakage. The support beading may take the form of a disposable,
round mandrel made of PTFE (Teflon) coated stainless steel wire or
other heat resistant material that does not readily bond to the
extrudate. By additionally limiting the area draw down ratio (ADDR)
to below 10:1 the tungsten-laden melt can successfully be drawn to
size by an extrusion puller. The beading provides the added benefit
of fixing the inner diameter and improving overall dimensional
stability of the final tungsten/polymer coating. Extrusions of a
91.3 weight percent fill ratio tungsten/Pebax composition described
above over 0.0215'' diameter PTFE beading were successfully drawn
down to a wall thickness of 0.0025'' to yield a marker properly
sized for attachment to for example a 0.022'' diameter inner member
of balloon catheter. Also, extrusion coatings of 91% compound over
0.007'' teflon coated stainless steel wire were successfully drawn
down to single wall thicknesses of 0.002'' to make guidewire
coatings.
[0188] In one embodiment, once the extrudate has cooled, the
extrusion is simply cut to the desired lengths (e.g., 1 to 1.5 mm)
of the individual markers, such as with the use of a razor blade
and reticle, preferably with the beading still in place to provide
support during cutting. The beading remnant is subsequently ejected
and the marker is slipped onto a medical device or a particular
component thereof. In one embodiment, a segment of the extrudate is
hot die necked with the beading inside to resize the outer diameter
and wall thickness of the extrudate prior to cutting into
individual markers. For example, an extrudate, having an inner
diameter of about 0.0215.+-.0.0005 inch and an outer diameter of
about 0.0275.+-.0.001 inch, is hot die necked to an outer diameter
of about 0.0265 inch to produce a double wall thickness of about
0.005.+-.0.005 inch. To minimize part to part variability in double
wall thickness, the actual hot die size may be selected based upon
the actual beading diameter prior to hot die necking.
[0189] Finally, the marker is attached to the underlying substrate,
preferably with the use of heat shrink tubing and a heat source
(hot air, laser, etc.) wherein the heat (.about.171-210.degree. C.)
simultaneously causes the marker to melt and the heat shrink tubing
to exert a compressive force on the underlying molten material. To
prevent extensive dimensional changes (e.g., thinning) of the
polymeric marker, the temperatures used are below the melting
temperature, thereby relying on heat and pressure to soften the
marker and generate an adhesive bond with the underlying substrate.
For markers formed of PEBAX 40D, the temperature used is about
120.degree.-135.degree. C. Heat bonding a marker onto an underlying
component provides the added benefit of slightly tapering the edges
of the marker to reduce the likelihood of catching an edge and
either damaging the marker or the medical device during assembly or
handling of the medical device.
[0190] A marker formed as per the above described compounding,
fabricating and assembling processes, having a fill ratio of 91.3
weight percent (36.4 volume percent) with a wall thickness of
0.0025'' has been shown to have dramatically more radiopacity than
commercially available 80 weight percent compounds and comparable
to the radiopacity of 0.00125 inch thick conventional Platinum/10%
Iridium markers. The radiopacity is a function of the total volume
of radiopaque material present in the marker (i.e., the product of
the volume % and the volume of the marker). In a presently
preferred embodiment, the marker is about 1.5 mm long and has a
double wall thickness of about 0.0045 to about 0.0055 inch and a
fill ratio of about 90.8 to about 93.2 weight percent of tungsten,
which provides a volume of radiopaque material substantially equal
to the volume of Platinum/10% Iridium in a 1.0 mm long, 0.0025 inch
thick (double wall) conventional Platinum/Iridium marker band.
Preferably, the volume of radiopaque material is not less than
about 30%, and the double wall thickness of the marker is at least
about 0.004 inch, to provide sufficient radiopacity. However, as
discussed above, the ability to increase the volume of the marker
by increasing the wall thickness of the marker is limited by the
resulting increase in profile and stiffness. In a presently
preferred embodiment, the double wall thickness of the marker is
not greater than about 0.006 inch.
[0191] In the embodiment illustrated in FIG. 29, three radiopaque
marker bands are provided on the second inner tubular member 174,
to facilitate positioning the distal end of the catheter 140 in
place in the patient's vasculature. In an alternative embodiment
(not shown), a single radiopaque marker is provided on the first or
second inner tubular member 172 or 174 as a carina marker band. The
single radiopaque marker is secured to the first or second inner
tubular member 172 or 174, preferably by adhesive bonding or
crimping, such that it is aligned with the proximal end of the
first balloon 166 or preferably aligned on the trap door opening of
the stent. The single radiopaque marker provides improved
manufacturability and flexibility compared to multiple markers.
[0192] Bifurcated catheter 140 is similar in many respects to the
catheter assembly 101 disclosed herein, and it should be understood
that the disclosure and individual features of the bifurcated
catheter 140 and catheter assembly 101 discussed and illustrated
with respect to one of the embodiments applies to the catheter
assembly 101 discussed and illustrated with respect to one of the
embodiments applies to the other embodiment as well. To the extent
not discussed herein, the various components of catheter 140 can be
formed of conventional materials used in the construction of
catheters, and joined together using conventional methods such as
adhesive bonding and fusion bonding. In one embodiment, the
proximal outer tubular member is formed of a relatively high
strength material such as a relatively stiff nylon material or a
metal hypotube. The intermediate tubular member and distal outer
tubular members are preferably formed of a polymeric material
including polyamides such as nylon or urethanes. The inner tubular
members preferably have at least an outer layer which is fusion
bondable (i.e., compatible) with the polymeric material of the
balloons and the coupler. In one embodiment, the coupler and distal
tip members are formed of a polyamide such as polyether block amide
(PEBAX) or blend thereof.
[0193] The materials used to construct the catheter assembly 101 or
140 are known in the art and can include for example various
compositions of PEBAX, PEEK (polyetherketone), urethanes, PET or
nylon for the balloon materials (polyethylene terephathalate) and
the like. Other materials that may be used for the various shaft
constructions include fluorinated ethylene-propylene resins (FEP),
polytetrafluoroethylene (PTFE), fluoropolymers (Teflon), Hytrel
polyesters, aromatic polymers, block co-polymers, particularly
polyamide/polyesters block co-polymers with a tensile strength of
at least 6,000 psi and an elongation of at least 300%, and
polyamide or nylon materials, such as Nylon 12, with a tensile
strength of at least 15,000 psi. The various shafts are connected
to each other using well known adhesives such as Loctite or using
heat-shrink tubing over the joint of two shafts, of which both
methods are well known in the art. Further, any of the foregoing
catheter materials can be combined with a compound that is visible
under MRI, such as 19F, as previously discussed herein.
Delivering and Implanting the Stent
[0194] Referring to FIGS. 35-41, the bifurcated catheter assembly
of the present invention provides two separate balloons in parallel
which can be advanced into separate passageways of an arterial
bifurcation and inflated either simultaneously or independently to
expand and implant a stent. As shown in the drawings, bifurcation
300 typically includes a main vessel 301 and a side branch vessel
302 with the junction between the two referred to as the carina
304. Typically, plaque 305 will develop in the area around the
junction of the main vessel and the side branch vessel and, as
previously described with the prior art devices, is difficult to
stent without causing other problems such as portions of the stent
extending into the blood flow path jailing a portion of the side
branch vessel, or causing plaque to shift at the carina and
subsequently occlude the vessel.
[0195] In keeping with the invention, the catheter assembly 101 or
140 is advanced through a guiding catheter (not shown) in a known
manner. Once the distal end 102 of the catheter reaches the ostium
to the coronary arteries, the Rx guide wire 310 is advanced
distally into the coronary arteries (or any other bifurcated
vessel) so that the Rx guide wire distal end 311 extends past the
opening to the side branch vessel 303. (In most cases, the main
vessel will have been predilated in a known manner prior to
delivery of the trap door stent. In these cases, the Rx guide wire
will have been left in place across and distal to the target site
prior to loading the catheter assembly onto the Rx guide wire for
advancement to the target site.) After the distal end of the Rx
guide wire is advanced into the main vessel past the opening to the
side branch vessel, the catheter is advanced over the Rx guide wire
so that the catheter distal end 102 is just proximal to the opening
to the side branch vessel. Up to this point in time, the OTW guide
wire 312 (or mandrel) remains within the catheter and within
coupler 119 keeping the tips and balloons joined. More
specifically, the OTW guide wire remains within the OTW guide wire
lumens 105,108, and 130 as previously described. The distal end of
the OTW guide wire 313 is positioned within coupler blind lumen 121
during delivery and up to this point in time. As the catheter is
advanced through tortuous coronary arteries, the OTW guide wire
distal end 313 should be able to slide axially a slight amount
relative the coupler blind lumen to compensate for the bending of
the distal end of the catheter. As the catheter distal end moves
through tight twists and turns, the coupler moves axially relative
to the balloon shaft that it is not attached to thereby creating
relative axial movement with the OTW guide wire. Stated
differently, the coupler moves axially a slight amount while the
OTW guide wire remains axially fixed (until uncoupled) relative to
the catheter shaft. If the OTW guide wire were fixed with respect
to the coupler at the distal end, it would make the distal end of
the catheter stiffer and more difficult to advance through the
coronary arteries, and may cause the distal end of the catheter to
kink or to be difficult to push through tight turns. Thus, the
coupler moves axially relative to the distal end of the OTW guide
wire in a range of approximately 0.5 mm up to about 5.0 mm.
Preferably, the coupler moves axially relative to the OTW guide
wire distal end 313 about 0.5 mm to about 2.0 mm. The amount of
axial movement will vary depending on a particular application and
the severity of the tortuousity. The proximal end of the OTW guide
wire (or joining wire or mandrel) should be removably fixed
relative to the catheter shaft during delivery so that the distal
end of the OTW guide wire does not prematurely pull out of the
coupler. The distal end of the OTW guide wire still moves axially a
small amount within the coupler as the distal end of the catheter
bends and twists in negotiating tortuous anatomy.
[0196] As previously disclosed and as shown in FIG. 28A, radiopaque
markers 140 are positioned on the inner shaft and coincide or align
with the long balloon 117 and the short balloon 129. The radiopaque
markers will assist the position in positioning the catheter
assembly 101, and more specifically the long balloon and short
balloon with respect to the opening to the side branch vessel 303.
Typically, it is desirable to have one radiopaque marker centered
with respect to the length of the long balloon, and perhaps several
other radiopaque markers defining the overall length of the long
balloon, or defining the length of the unexpanded or expanded stent
20. Similarly, a radiopaque marker associated with the short
balloon is preferably aligned with the center radiopaque marker of
the long balloon.
[0197] As shown for example in FIG. 36, the OTW guide wire 312 next
is withdrawn proximally so that the OTW guide wire distal end 313
is removed from the coupler blind lumen 121. As shown in FIG. 37,
the OTW guide wire next is advanced distally into the side branch
vessel 302, extending past the opening to the side branch vessel
303 and advancing distally into the vessel for a distance as shown
in FIG. 38. Once the Rx guide wire 310 is in position in the main
vessel, and the OTW guide wire 312 is in position in the side
branch vessel, this will have a tendency to impart a slight
separation between the long balloon 117 and the short balloon 129.
As shown in FIG. 39, the catheter assembly 101 is advanced distally
over the Rx guide wire and the OTW guide wire and, as the assembly
is further advanced, the long balloon 117 continues to separate
from the short balloon 129 as each advances into the main vessel
301 and the side branch vessel 302 respectively. As the assembly
continues to advance distally, it will reach the point where portal
section 22 on the stent 10 is adjacent the opening to the side
branch vessel 303. At this point, the catheter assembly can no
longer be advanced distally since the stent is now pushing up
against the opening to the side branch vessel. The long balloon 117
and the short balloon 129 are next inflated simultaneously to
expand the stent 10 into the main vessel and into the opening to
the side branch vessel. As shown in FIG. 40, a portion of the
portal section 22 of the stent will expand into contact with the
opening to the side branch vessel and the portal section 22 of the
stent should coincide with the opening to the side branch vessel
providing a clear blood flow path through the proximal end 12 of
the stent and through the portal section 22 into the side branch
vessel. The expanded stent 10 is shown in FIG. 40 covering a
portion of the main vessel and the opening to the side branch
vessel.
[0198] In keeping with the invention, as the catheter assembly is
advanced through tortuous coronary arteries, the portal section 22
of the stent 10 may or may not always be perfectly aligned with the
opening to the side branch vessel 303. If the portal section of the
stent is in rotational alignment with the opening to the side
branch vessel, the stent is said to be "in phase" and represents
the ideal position for stenting the main branch vessel and the
opening to the side branch vessel. When the portal section and the
opening to the side branch vessel are not rotationally aligned it
is said to be "out of phase" and depending upon how may degrees out
of phase, may require repositioning or reorienting the portal
section 22 with respect to the opening to the side branch vessel.
More specifically, the mis-alignment can range anywhere from a few
degrees to 360.degree.. If the central opening is in excess of
90.degree. out of phase with respect to the opening to the side
branch vessel, it may be difficult to position the stent with
respect to the longitudinal axis. When the out of phase position is
approximately 270.degree. or less, the stent 10 still can be
implanted and the portal section will expand into the opening to
the side branch vessel and provide adequate coverage provided that
the stent and radiopaque markers can be positioned longitudinally.
Due to the unique and novel design of the catheter assembly and the
stent of the present invention, this misalignment is minimized so
that the portal section 22 generally aligns with the opening to the
side branch vessel, even if the central opening is out of phase
approximately 90.degree. from the opening of the side branch vessel
303. Typically, the alignment between the portal section 22 and the
opening to the side branch vessel will be less than perfect,
however, once the OTW guide wire 312 is advanced into the side
branch vessel 302, as previously described, the assembly will
slightly rotate the portal section 22 into better alignment with
the opening to the side branch vessel. As can be seen in FIGS.
35-39, after the stent has been properly oriented, it is expanded
into contact with the main branch vessel and the portal section 22
expanded to contact with the opening to the side branch vessel.
[0199] As shown in FIG. 41, a second stent 320 can be implanted in
the side branch vessel 302 such that it abuts portal section 22 of
stent 10. The second stent can be delivered and implanted in the
following manner. After implanting stent 10, the long balloon 117
and the short balloon 119 are deflated and catheter assembly 101
(or 140) are removed from the patient by first withdrawing the Rx
guide wire 310 and then withdrawing the catheter assembly over the
in-place OTW guide wire 312 (an extension guide wire which is known
in the art may be required), which remains in the side branch
vessel 302. Alternatively, the catheter assembly can be withdrawn
from the patient while leaving both the Rx and OTW guide wires in
place in their respective vessels. Next, a second catheter assembly
(not shown) on which second stent 320 is mounted, is backloaded
onto the proximal end of the OTW guide wire 312. The catheter
assembly is next advanced through the guiding catheter and into the
coronary arteries over the OTW guide wire, and advanced such that
it extends into proximal end 12 of the expanded and implanted stent
10. The second catheter assembly is advanced so that it extends
through the opening to the side branch vessel and advances over the
OTW guide wire 312 and into the side branch vessel where second
stent 320 can be expanded and implanted in the side branch vessel
to abut the portal section 22 of stent 10. Alternatively, the
catheter assembly 101 can be withdrawn to just proximal of the
bifurcation, the Rx guide wire 310 withdrawn proximally into the
catheter, and then the catheter assembly advanced into the side
branch vessel over the in-place OTW guide wire 312. The Rx guide
wire can then be advanced into the side branch vessel, the OTW
guide wire safely withdrawn into the catheter assembly, and the
catheter assembly then safely removed in an Rx exchange over the Rx
guide wire which remains in place in the side branch vessel.
Thereafter the second catheter assembly can be advanced over the
in-place Rx guide wire 310 and into the side branch vessel where
the second stent is implanted as previously described. Care must be
taken in this approach to avoid wire wrapping, that is avoiding
wrapping the Rx and OTW guide wires in the side branch vessel.
[0200] In another alternative embodiment for implanting second
stent 320, the long balloon 117 and the short balloon 119 are
deflated and catheter assembly 101 is removed from the patient by
first withdrawing OTW guide wire 312 so that it resides within the
catheter assembly, and then withdrawing the catheter assembly over
the in-place Rx guide wire 310, which remains in the main vessel
301. Next, a second catheter assembly (not shown) on which second
stent 320 is mounted, is back loaded onto the proximal end of Rx
guide wire 310, advanced through the guiding catheter into the
coronary arteries, and advanced such that it extends into the
proximal end 12 of the expanded and implanted stent 10. The Rx
guide wire is then withdrawn proximally a short distance so that
the Rx guide wire distal end 311 can be torqued and rotated so that
it can be advanced into the side branch vessel 302. Once the Rx
guide wire is advanced into the side branch vessel, the second
catheter is advanced and the second stent 320 is positioned in the
side branch vessel where it is expanded and implanted in a
conventional manner as shown in FIG. 41. The second catheter
assembly is then withdrawn from the patient over the Rx guide
wire.
[0201] In an alternative method of deploying and implanting stent
10, the catheter assembly 101 as shown in FIGS. 35-41 can be
adapted to carry a mandrel (not shown) instead of the OTW guide
wire. For example, during delivery and positioning of the stent in
the main branch vessel 301, a mandrel resides in the OTW guide wire
lumens 105,108, and 130, and the distal end of the mandrel extends
into and resides in coupler blind lumen 121. As the catheter
assembly is positioned just proximal to the bifurcation, such as
shown in FIGS. 35 and 36, the mandrel is withdrawn proximally from
the catheter assembly allowing the long balloon 117 and the short
balloon 129 to slightly separate. Thereafter, an OTW guide wire 312
is frontloaded into the proximal end of the catheter assembly and
advanced through the OTW guide wire lumens and into the side branch
vessel 302 as shown in FIGS. 37 and 38. After this point, the
delivery and implanting of the stent is the same as previously
described.
[0202] In an alternative method of delivering and implanting the
stent of the invention, the catheter assembly 101 or 140 is
advanced through a guiding catheter (not shown) in a known manner.
Once the distal end 102 of the catheter reaches the ostium to the
coronary arteries, the Rx guide wire 310 is advanced out of the Rx
shaft 111 and advanced distally into the coronary arteries (or any
other bifurcated vessels) so that the Rx guide wire distal end 311
extends through the opening to the side branch vessel 303. (As
noted above, the Rx guide wire may already be positioned in the
main vessel or side branch vessel as a result of a pre-dilatation
procedure). After the distal end of the Rx guide wire is advanced
into the side branch vessel, the catheter is advanced over the Rx
guide wire so that the catheter distal end 102 is positioned distal
to the opening to the side branch vessel and partially within the
side branch vessel. More specifically, the short tip of the short
balloon 129 should be distal to the carina 304. Up to this point in
time, the OTW guide wire 312 remains within the catheter and within
coupler 119. More specifically, the OTW guide wire remains within
the OTW guide wire lumens 105,108,130 as previously described. The
distal end of the OTW guide wire 313 is positioned within coupler
blind lumen 121 during delivery and up to this point in time. As
the catheter is advanced through tortuous coronary arteries, for
example, the OTW guide wire distal end 313 should be able to move
axially a slight amount within the coupler blind lumen to
compensate for the bending of the distal end of the catheter. If
the OTW guide wire were fixed with respect to the catheter shaft
and the coupler at the distal end, it would make the distal end of
the catheter stiffer and more difficult to advance through the
coronary arteries, and may cause the distal end of the catheter to
kink or be more difficult to push through tight turns. Thus, the
distal end of the OTW guide wire will move axially in a range of
approximately 0.5 mm up to about 5.0 mm. Preferably, the OTW guide
wire distal end 313 will move back and forth axially about 0.5 mm
to about 2.0 mm. The amount of axial movement depends on a
particular application or vessel tortuousity. The proximal end of
the OTW guide wire should be removably fixed relative to the
catheter shaft during delivery so that the distal end of the OTW
guide wire does not prematurely pull out of the coupler. The distal
end of the OTW guide wire still moves axially a small amount within
the coupler as the distal end of the catheter bends and twists in
negotiating tortuous anatomy.
[0203] The OTW guide wire 312 next is withdrawn proximally so that
the OTW guide wire distal end 313 is removed from the coupler blind
lumen 121. The OTW guide wire next is advanced distally into the
side branch vessel 302 a short distance. The catheter assembly is
next withdrawn proximally so the long balloon 117 and the short
balloon 129 are in the main vessel just proximal of the opening of
the side branch vessel. More specifically, the coupler distal tip
is proximal to vessel carina 304. As the catheter assembly is
withdrawn from the side branch vessel, the long balloon and short
balloon will begin to separate slightly. Thereafter, the Rx guide
wire 310 is withdrawn proximally until it is clear of the opening
to the side branch vessel, whereupon it is advanced distally into
the main branch vessel for a distance. The catheter assembly next
is advanced distally over the Rx guide wire in the main branch
vessel and the OTW guide wire in the side branch vessel. As the
catheter advances distally, the long balloon and short balloon will
separate at least partially until the short balloon enters the side
branch vessel and the long balloon continues in the main branch
vessel. As the balloons and stent push up against the ostium of the
bifurcation, the catheter assembly cannot be advanced further and
the stent is now in position to be expanded and implanted. At this
point the radiopaque markers should be appropriately positioned.
The portal section 22 on the stent 10 should be approximately
adjacent the opening to the side branch vessel 303. The long
balloon 117 and the short balloon 129 are next inflated
simultaneously to expand the stent 10 into the main vessel and into
the opening into the side branch vessel respectively. A portion of
the portal section 22 of the stent will expand into contact with
the opening to the side branch vessel and the portal section 22 of
the stent should coincide to the opening of the side branch vessel
providing a clear blood flow path through the proximal end 12 of
the stent and through the portal section 22 into the side branch
vessel. When fully expanded, stent 10 should cover at least a
portion of the main vessel and the opening to the side branch
vessel. After the stent has been expanded and implanted, the
balloons are deflated and the assembly is withdrawn from the
vascular system over the Rx and OTW guide wires. The Rx and OTW
guide wires remain in place in the main and side branch vessels for
further procedures.
[0204] The above procedures can also be performed with a spare
safety wire placed in the alternate vessel. The safety wire is
removed from the patient after the OTW guide wire has been advanced
into the side branch vessel (first case) or the Rx guide wire has
been advanced into the distal main vessel (second case). The safety
wire allows access to the vessel should closure from a dissection
or spasm occur.
[0205] As can be seen in FIGS. 42-45, the OTW guide wire 312 on
occasion can be inadvertently torqued in the wrong direction and
wrap around the distal end 102 of the catheter or around the
coupler 119 prior to advancing into the side branch vessel 302. If
this occurs, and the OTW guide wire is advanced into the side
branch vessel, the catheter assembly can be advanced distally only
a certain distance before the crossed wires reach the junction or
carina of the main vessel and the side branch vessel and the
catheter can no longer be advanced distally. At this point, the
physician knows that the wires are wrapped or that the central
opening is severely out of alignment with the opening of the side
branch vessel, in which cases the OTW guide wire 312 is withdrawn
proximally into the catheter and the catheter assembly is
reoriented by rotating the assembly to better position the portal
section 22 with respect to the opening to the side branch vessel
prior to advancing the OTW guide wire 312. Thus, as shown in FIG.
45, once the guide wires are wrapped, the OTW guide wire must be
withdrawn proximally, and then readvanced into the side branch
vessel taking care to avoid wrapping. The catheter assembly would
then be readvanced in an effort to reorient the portal section 22
with the opening to the side branch vessel.
[0206] If it becomes impossible to deliver the stent for whatever
reason, including that described above with respect to the wrapped
guide wires, the catheter assembly 101 can be withdrawn into the
guiding catheter and removed from the patient. Typically, the OTW
guide wire 312 would be withdrawn proximally into the catheter and
the catheter assembly would be withdrawn proximally over the Rx
guide wire which remains in place in the main vessel 301.
Alternatively, as the catheter assembly is withdrawn, the stent can
be safely implanted proximal to the bifurcation. If desired, a
second catheter assembly can be backloaded over in-place Rx guide
wire 310 and advanced through the guiding catheter and into the
coronary arteries as previously described to implant another
stent.
[0207] FIG. 46 illustrates an alternative embodiment of a stent
delivery balloon catheter 600 embodying features of the invention,
generally comprising an elongated shaft 610, a first balloon 611, a
second balloon 612, and a stent 613 releaseably mounted on the
first and second balloons for delivery and deployment within a
patient's bifurcated body lumen. The elongated shaft 610 has a
proximal section 614 having a first inflation lumen 615, and a
bifurcated distal section 616 having a first branch 617 with a
second inflation lumen 618 within at least a portion thereof and a
second branch 621 with a third inflation lumen 622 within at least
a portion thereof, as best illustrated in FIGS. 47-49, illustrating
cross sectional views of the catheter of FIG. 46. The second and
third inflation lumens 618, 622 are each in fluid communication
with the first inflation lumen 615. An intermediate section 623
extends between the proximal section and the branched distal
section, and has a fourth inflation lumen 624 in fluid
communication with the first, second, and third inflation
lumens.
[0208] In the embodiment illustrated in FIG. 46, the proximal shaft
section 614 comprises a proximal outer tubular member defining the
first inflation lumen 615, the first branch 617 of the bifurcated
distal shaft section 616 is formed in part by a first distal outer
tubular member 634, and the second branch 621 is formed in part by
a second distal outer tubular member 636. The intermediate shaft
section 623 comprises an intermediate outer tubular member defining
the fourth inflation lumen 624. In the embodiment illustrated in
FIG. 46, the intermediate outer tubular member is a separate
tubular member secured to the distal end of the proximal outer
tubular member. However, a variety of suitable configurations can
be used to transition from the proximal shaft section to the
bifurcated distal shaft section, including alternative embodiments
(not shown) in which the intermediate section 623 (or intermediate
outer tubular member) is an integral, one piece unit with the
proximal section 614, formed by a distal end portion of the
proximal section 614.
[0209] A joining wire lumen 625 extends within the proximal
section, the intermediate section, and the first branch, and a
rapid exchange guidewire lumen 626 extends within the intermediate
section and the second branch. A proximal adapter 619 is secured to
the proximal end of the catheter shaft, which has an arm configured
for connecting to a source of inflation fluid for inflating the
balloons 611, 612, and which provides access to joining wire lumen
625.
[0210] In the illustrated embodiment, the first branch 617
comprises an inner tubular member 633 defining the joining wire
lumen 625 and outer tubular member 634 defining, together with the
outer surface of the inner tubular member 625 therein, the second
inflation lumen 618 in the annular space between the inner and
outer tubular members 633, 634 (see FIG. 49). The second branch 621
similarly comprises an inner tubular member 635 defining the
guidewire lumen 626 and outer tubular member 636 defining, together
with the outer surface of the inner tubular member 625 therein, the
third inflation lumen 622.
[0211] In a presently preferred embodiment, the first balloon 611
is a shorter balloon on an OTW branch of the catheter 600 and the
second balloon 612 as a longer balloon on a Rx branch of the
catheter 600. However, in an alternative embodiment (not shown),
the shorter balloon is on an Rx branch and the longer balloon is on
an OTW branch of the catheter 600. In the embodiment of FIG. 46,
the proximal ends of the first and second balloons 611, 612 are
radially aligned. Specifically, although the inflatable length of
the first balloon 611 is substantially shorter than that of the
second balloon 612, the first balloon has an extended proximal
skirt section sealingly secured to the shaft, which extends
proximally to a location radially aligned with the proximal end of
the proximal skirt section of the second balloon 612, in the
embodiment of FIG. 46. In the embodiment of FIG. 46, the distal
ends of the first and second branch outer tubular members 634,636
are radially aligned. In an alternative embodiment (not shown), the
first branch outer tubular member 634 has a distal end section
which extends longitudinally along the extended proximal skirt
section of the first (shorter) balloon 611, to a location distal to
the distal end of the second branch outer tubular member 636.
[0212] The bifurcated distal section has a first secured portion
and a second secured portion along which the first and second
branches are permanently secured together, and which in the
illustrated embodiment are formed at least in part by first and
second tubular outer band members 627, 628 which surround and
thereby constrain the first and second branches of the distal shaft
section together. FIGS. 47 and 48 illustrate enlarged, longitudinal
sectional views of the catheter of FIG. 46, taken within circles 47
and 48, respectively. FIG. 47 illustrates the first tubular outer
band member 627 on the first and second branches 617, 621 of the
catheter. The tubular outer band members 627, 628 constrain the
first and second branches together, thus bringing and holding the
first and second branches in contact with one another along the
secured portions formed thereby, when the balloons are in a
deflated or inflated configuration (see, e.g., FIG. 55 which
illustrates the inflated balloons and which is discussed in more
detail below). The tubular outer band members are preferably a
solid-walled length of tubing, and thus extend continuously around
the circumference thereof.
[0213] The secured portions 627, 628 are located proximal to the
proximal end of the stent 613 mounted on the first and second
balloons. The first secured portion 627 is located approximately
midway between a proximal end of the first and second balloons and
a proximal end of the branched distal shaft section. A first
unsecured portion 631, along which the first and second branches
are not secured together, is proximally adjacent to the first
secured portion. The second secured portion is distally spaced
apart from the first secured portion by an unsecured portion 632.
In the embodiment illustrated in FIG. 46, the second secured
portion 628 is located adjacent to but proximally spaced apart from
the proximal end of the first and second balloons. In one
embodiment (not shown), the first and second branches have a single
tubular outer band member securing the branches together, and
generally located approximately midway between the location of the
first and second bands 627, 628 in the embodiment of FIG. 46 such
that unsecured portions are adjacent to the proximal and the distal
end of the single tubular outer band member.
[0214] In a presently preferred embodiment, the tubular outer band
members are a heat shrinkable polymer such as polyester heat shrink
tubing, which is heat shrunk onto the first and second branches.
Preferably, adhesive (not shown) is provided under the outer band
members to adhesively secure the band members to the first and
second branches of the distal shaft section.
[0215] The outer band members are preferably molded or otherwise
caused to conform to the shape of the first and second outer
tubular members secured together. For example, in a presently
preferred embodiment, with the outer band members 627, 628 in place
on the first and second branches, each secured portion (i.e., at
the location of each outer band member 627, 628) is heated in a
mold with an internal chamber configured to force the band member
against the underlying shaft surface, thereby causing the band
member to conform to outer surfaces of the first and second outer
tubular members, 634, 636, secured together. Preferably, the
assembly inside the mold is heated by conduction, i.e., from the
heated mold wall. As best illustrated in FIG. 49, showing a
transverse cross section taken along lines 49-49 in FIG. 48, the
resulting applied outer band member has an hourglass shape
corresponding the shape of the exposed surfaces of the first and
second outer tubular members 634, 636, brought together. The
molding process thus avoids the tendency of shrink tubing to shrink
down to an oval, non-hourglass, transverse cross-sectional shape
around the two outer tubular members 634, 636. As a result, a
potential gap between a part of the inner surface of the heat
shrunk outer band member and the outer surface of the outer tubular
members thereunder is thus avoided, for improved catheter
performance. In a presently preferred embodiment, the outer band
members 627, 628 are heat shrunk onto the outer tubular members
634, 636, with adhesive therebetween, and molded to conform to the
outer surfaces of the outer tubular members 634, 636, to form a
secure, low profile attachment with no gaps between the adjacent
surfaces.
[0216] FIG. 46 illustrates the first and second branches joined
together by a joining guidewire 637, and with the balloons in a
deflated configuration prior to being inflated. For ease of
illustration a space is shown between the inner surfaces of the
balloons and the inner members therein, although it should be
understood that the inner surface of the balloon along the
inflatable interior is typically collapsed down to the inner member
of the shaft in the deflated configuration to minimize the profile
of the device during positioning in the body lumen. The distal end
of the joining guidewire 637 is positioned within coupler 639 which
is secured to the second branch and which is located distal to the
inflatable interior of the second balloon 612, configured for
releasably coupling the first and second branches together to form
a coupled configuration. A second guidewire 641 is illustrated
slidably disposed in the guidewire lumen 626.
[0217] The catheter 600 further includes a polymeric radiopaque
distal tip marker 643 surrounding a distal end section of the first
617 lumen, formed of a blend of polymeric and radiopaque material.
A presently preferred blend has about 91 weight percent of a
radiopaque material such as tungsten. In the illustrated
embodiment, the polymeric radiopaque distal tip marker 643 is an
annular ring on an outer surface of a distal end section of the
first branch 617 (see FIG. 50 illustrating an enlarged longitudinal
cross section of the distal end of the first branch 617 taken
within circle 50 in FIG. 46, and FIG. 51 illustrating a transverse
cross section taken along line 51-51 in FIG. 50).
[0218] In embodiment of FIG. 50, the first branch includes a distal
tip member 644 at the distal end of the first branch 617 having a
joining wire lumen therein (i.e., the distal tip member 644 defines
the distal-most end section of the joining wire lumen, in
communication with the section of the joining wire lumen defined by
the first inner tubular member 633) The polymeric radiopaque tip
marker 643 surrounds and is secured to an outer surface of a
section of an outer sheath on the distal tip member 644. However,
in an alternative embodiment (not shown), the annular ring marker
643 is omitted, and the distal tip member 644 is formed of the
blend of polymeric and radiopaque materials to thereby function as
the polymeric radiopaque distal tip marker. In the embodiment of
FIG. 50, the distal tip member 644 is butt-joined to the distal end
of the first inner tubular member 633, and an outer sheath
surrounds the distal end of the first branch and the proximal end
of the distal tip member 644, although a variety of suitable
configurations can be used. In the illustrated embodiment, the
outer sheath is a polymeric sleeve member 645 extending from the
distal end of the balloon 611 and sealingly surrounding the
butt-joint. In an alternative embodiment, the sleeve member 645 is
omitted and the balloon distal skirt section, sealingly secured to
the shaft, forms the outer sheath extending over the butt-joint.
The outer sheath is preferably nonradiopaque. In the illustrated
embodiment, the polymeric sleeve member 645 extends distally to the
distal end of the distal tip member 644, although in alternative
embodiments (not shown) the length of the sleeve member 645 can
vary.
[0219] The distal tip member 644 is typically formed of a
relatively soft polymeric material, to provide an atraumatic distal
tip. The soft distal tip member 644 and/or polymeric sleeve member
645 typically have at least an outer layer formed of a polymeric
material compatible with the polymeric material of the polymeric
radiopaque tip marker 643. For example, in a presently preferred
embodiment, the soft distal tip member, polymeric sleeve, and the
polymeric radiopaque distal tip marker are formed of polyether
block amide copolymers (PEBAX) having the same or different
durometer hardnesses. In one embodiment, the distal tip member 644
and marker 643 are formed of PEBAX 63D.
[0220] The polymeric radiopaque distal tip marker 643 is typically
heat fusion bonded to the first branch of the catheter. During heat
fusion, e.g. laser, bonding, the polymeric radiopaque distal tip
marker 643 typically softens and flows. Although allowed to flow
during bonding, the marker 643 typically retains a band-like shape.
The marker shown in FIG. 50 has sharp edges for ease of
illustration, however, it should be understood that the laser
bonded polymeric radiopaque distal tip marker 643 typically has
rounded edges, and preferably provides a gradual stiffness
transition, unlike a metal marker band. Although not illustrated,
in one embodiment the polymeric radiopaque tip marker 643 is shaped
so that after being bonded to the shaft it has a distally tapering
wall thickness for improved tip entry/track performance.
[0221] The catheter includes one or more balloon radiopaque markers
646 on the inner tubular members 633, 636, located within the
inflatable interiors of the balloons 611, 612. The balloon
radiopaque markers 646 indicate the proximal end, the distal end
and the central opening of the stent 613. In a presently preferred
embodiment, the polymeric radiopaque tip marker 643 appears under
fluoroscopy with a shape that is visually different than balloon
radiopaque markers 646. For example, in a presently preferred
embodiment, the balloon radiopaque markers 646 are metallic
radiopaque rings (i.e., they consist essentially of metal such as
Pt/Ir, and not a polymeric radiopaque blend), which appear under
fluoroscopy with a sharper, less rounded image than the polymeric
radiopaque distal tip ring 643 Additionally, depending on the
radiopacity/percent loading of the polymeric radiopaque blend, the
metallic radiopaque rings 646 are typically brighter (more highly
radiopaque) than the polymeric radiopaque blend Because the balloon
metal markers are typically very bright with distinct edges
compared to the polymeric blend marker on the tip, the ability to
tell the different markers apart under fluoroscopy is facilitated.
In an alternative embodiment, the balloon radiopaque markers 646
are also formed of a blend of polymeric and radiopaque materials,
so that the polymeric radiopaque distal tip marker 643 preferably
has a different physical characteristic such as length or shape
than the balloon markers 646 or has a different radiopacity/percent
loading than the balloon markers 646, to thereby appear visually
different under fluoroscopy.
[0222] The polymeric radiopaque distal tip marker 643 has a length
shorter than the length of the distal tip member 644, and is spaced
apart from and between the distal end of the sleeve member 645 and
from the distal end of the distal tip member 644. However, the
polymeric radiopaque distal tip marker 643 can have a variety of
suitable lengths. In one embodiment, the polymeric radiopaque
distal tip marker 643 has a length which is about 0.5 mm to about 2
mm, preferably about 1 mm, and which is the same as the length of
the balloon radiopaque markers 646. The polymeric radiopaque distal
tip marker 643 typically has a relatively thin wall thickness,
thinner than the underlying section of the shaft.
[0223] In the embodiment of FIG. 46, the joining wire 637 has a
proximal end fixedly secured to a connector 620 connected to the
proximal adapter 619. Thus, the joining wire 637 cannot be used to
access the side branch of the patient's bifurcated body lumen and
position the stent within the bifurcation, and the joining wire 637
is therefore removed from the catheter prior to stent deployment
and replaced with a new guidewire having a torquer thereon for use
in positioning the first balloon 611 in the side branch of the
patient's body lumen.
[0224] In an alternative embodiment illustrated in FIG. 52, the
catheter includes a guidewire locking mechanism 650 located
proximal to the catheter shaft, having a locked mode in which the
catheter is releasably locked to a joining guidewire 651, so that
joining guidewire 651 does not have to be replaced with a new
guidewire for accessing the side branch of the patient's body
lumen. In the embodiment of FIG. 52, the guidewire locking
mechanism 650 comprises a collet member 652 having a radially
collapsible slotted head 653 positioned within the proximal adapter
619 (at least when in the locked mode), and a proximal fitting 654
(i.e., a luer cap) connected to the proximal adapter 619 and which
tightens down onto the proximal adapter to place the guidewire
locking mechanism in the locked mode. Specifically, as the proximal
fitting 654 is rotated to tighten onto the proximal Y-arm adapter
619 luer connector, the jaws of the collet head are radially
compressed on the joining guidewire, locking it in place. In the
illustrated embodiment, the collet member is facing distally with
the body of the collet member housed at least in part in the
proximal fitting 654, although it can alternatively face proximally
with the body housed in the guidewire lumen of the proximal
adapter. The joining guidewire 651 is disposed in lumen 655 in the
proximal fitting 654 and in the collet member 652 lumen, and has a
proximal end extending proximally from the proximal end of the
proximal fitting 654.
[0225] However, a variety of suitable guidewire locking mechanisms
can be used, including forming the radially collapsible slotted
head as an integral (e.g., molded) part of the proximal fitting
654. For example, FIG. 53 illustrates an embodiment in which the
guidewire locking mechanism 650 is a proximal fitting 656
releasably connected to the proximal adapter 619 luer fitting, and
having an inner extension member 657 with a radially collapsible
slotted head 658 configured to releasably lock to joining guidewire
651 when the proximal fitting is tightened onto the proximal
adapter.
[0226] FIG. 54 illustrates an alternative embodiment in which the
guidewire locking mechanism 650 includes a guidewire locking torque
handle 663 The guidewire locking torque handle 663 is releasably
connected to a proximal end of the proximal adapter 619, to lock
the joining guidewire 651 to the catheter as discussed above in
relation to the guidewire locking mechanism of FIG. 52. Thus, the
releasable connection between the proximal adapter 619 and the
fitting 662 of the handle assembly in the embodiment illustrated in
FIG. 50 is formed by a threaded luer type fitting. Additionally,
with the guidewire locking torque handle 663 and proximal fitting
662 tightened together, the slotted head of the collet 665
reversibly engages the joining guidewire 651, such that the body
663 extending therealong provides a finger hold for use as a torque
handle for manipulating the joining guidewire 651. The proximal
fitting 662 can alternatively be a rotating type of luer fitting,
allowing the joining guidewire 651 to be rotated while fixing the
axial position of the wire 651.
[0227] In the embodiment of FIG. 54, the joining guidewire 651 can
be unlocked from the catheter by disconnecting the proximal fitting
662 from the proximal adapter 619 (by rotating the proximal fitting
662 off the proximal adapter 619), and/or by disengaging the
guidewire locking torque handle from the joining guidewire 651. For
example, the collet can first be loosened, and then the device
unlocked from the sidearm proximal adapter and slid along the
joining guidewire, thus leaving the joining guidewire in place. The
handle 663 is disengaged from the joining guidewire 651 by
unthreading the handle 663 from the cap formed by the proximal
fitting 662. The location of the handle 663 on the joining
guidewire 651 can be adjusted by sliding the disengaged handle
along the joining guidewire, and then reengaging the handle onto
the joining guidewire in the desired location by tightening the
proximal fitting onto the handle. The handle 663, engaged on the
joining guidewire 651, is then grasped during positioning of the
joining guidewire in the patient's branch vessel. The joining
guidewire 651 distal tip can be fixed in a retracted position
within the lumen 625 of the catheter or in an extended position
distally outside the catheter distal tip. Although discussed
primarily in term of use with a bifurcated stent delivery catheter,
it should be understood that the guidewire locking torque handle
can be used with a variety of suitable catheters to provide a
slidable guidewire in a stable and fixed position relative to the
catheter in the releaseably locked configuration.
[0228] A method of delivering a stent to a patient's bifurcated
blood vessel generally comprises introducing within the blood
vessel a stent delivery balloon catheter of the invention (e.g.,
catheter 600). The catheter is advanced within the patient's blood
vessel towards a opening of a side branch of the patient's blood
vessel, with the first and second branches of the catheter distal
section in a reversibly coupled configuration. The method includes
fluoroscopically imaging the polymeric radiopaque distal tip marker
to determine the alignment of the first branch balloon relative to
the opening of the side branch of the patient's blood vessel,
uncoupling the first and second branches to an uncoupled
configuration, positioning the uncoupled first branch of the
catheter within the side branch of the patient's blood vessel, and
expanding the stent. If necessary for proper placement, the
alignment of the first branch balloon relative to the side branch
opening of the patient's blood vessel is adjusted by
fluoroscopically imaging the polymeric radiopaque distal tip marker
either before or after the first and second branches are uncoupled.
In the embodiment of FIG. 46, the first and second branches are
held together at the secured portions 627, 628 to advance together
as a unit within the body lumen. With the catheter advanced to the
location of the opening of a side branch of the patient's blood
vessel, the first branch is positioned in the side branch blood
vessel by advancing the catheter in the uncoupled configuration, so
that a distal tip of the uncoupled first branch advances radially
away from the second branch into the side branch of the patient's
blood vessel and the first and second branches advance together at
the secured portion. FIG. 55 illustrates the an elevational view of
balloon catheter 600 within a patient's bifurcated blood vessel
670, with the first branch of the catheter positioned within the
side branch of the blood vessel, and with the balloons 611, 612
inflated to radially expand the stent at the blood vessel
bifurcation. As discussed above, it should be understood that a
catheter embodying features of the invention can be used for a
variety of medical procedures and disease states, which include, by
way of non-limiting examples, chronic total occlusions (CtO), and
diffuse disease, and regional therapies.
[0229] In one embodiment, a method of the invention includes
positioning the joining guidewire 651 distal end distal to the
distal end of the first branch and placing the guidewire locking
mechanism 650 in the locked mode to lock the catheter to the
joining guidewire, so that the joining guidewire functions as a
fixed guidewire. The catheter is then advanced together with the
fixed guidewire to the opening of the branch vessel. In the
unlocked mode, the joining guidewire is slidably disposed in the
joining wire lumen and thus no longer functions as a fixed
wire.
[0230] While particular forms of the invention have been
illustrated and described, it will be apparent to those skilled in
the art that various modifications can be made without departing
from the scope of the invention. Accordingly, it is not intended
that the invention be limited except by the appended claims.
* * * * *