U.S. patent application number 09/842401 was filed with the patent office on 2001-08-23 for stent and catheter assembly and method for treating bifurcations.
Invention is credited to Mauch, Kevin M., Wilson, W. Stan.
Application Number | 20010016767 09/842401 |
Document ID | / |
Family ID | 23631641 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016767 |
Kind Code |
A1 |
Wilson, W. Stan ; et
al. |
August 23, 2001 |
Stent and catheter assembly and method for treating
bifurcations
Abstract
An apparatus and method is provided for stenting bifurcated
vessels. A proximal angled stent is configured for implanting in a
side-branch vessel wherein the proximal angled stent has an
angulated portion that corresponds to the angle formed by the
intersection of the side-branch vessel and the main vessel so that
all portions of the side-branch vessel at the bifurcation are
covered by the proximal angled stent. A main-vessel stent is
provided for implanting in the main vessel, wherein the main-vessel
stent has an aperture or stent cell that aligns with the opening to
the side-branch vessel to permit unobstructed blood flow between
the main vessel and the side-branch vessel. Side-branch and
main-vessel catheter assemblies are advanced over a pair of guide
wires for delivering, appropriately orienting, and implanting the
proximal angled stent and the apertured stent.
Inventors: |
Wilson, W. Stan; (Missoula,
MT) ; Mauch, Kevin M.; (San Jose, CA) |
Correspondence
Address: |
FULWIDER PATTON LEE & UTECHT, LLP
HOWARD HUGHES CENTER
6060 CENTER DRIVE
TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Family ID: |
23631641 |
Appl. No.: |
09/842401 |
Filed: |
March 24, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09842401 |
Mar 24, 2001 |
|
|
|
09412113 |
Oct 5, 1999 |
|
|
|
Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61F 2250/006 20130101;
A61F 2002/067 20130101; A61F 2002/91516 20130101; A61F 2002/91575
20130101; A61F 2/954 20130101; A61F 2002/91508 20130101; A61F 2/91
20130101; A61F 2/915 20130101; A61F 2002/91533 20130101; A61F 2/856
20130101; A61F 2/958 20130101 |
Class at
Publication: |
623/1.11 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. A stent delivery assembly for treating bifurcated vessels having
a side-branch vessel and a main vessel, comprising: a side-branch
catheter having a proximal end and a distal end; an expandable
member proximate the distal end of the catheter; a tracking guide
wire lumen extending within at least a portion of the side-branch
catheter; a tracking guide wire having a distal end and a proximal
end and sized for slidable movement within the tracking guide wire
lumen; a positioning guide wire lumen associated with the
expandable member and adapted to receive for slidable engagement a
positioning guide wire, the positioning guide wire having a distal
end and a proximal end; the proximal ends of the tracking and
positioning guide wires extend out of the patient and can be
manipulated so that the distal end of the positioning guide wire is
advanced in the main vessel distal to the side-branch vessel, and
the distal end of the tracking guide wire is advanced into the
side-branch vessel.
2. The stent delivery assembly of claim 1, wherein the positioning
guide wire lumen is attached to an outer surface of the catheter
and extends along to just proximal of the expandable member.
3. The stent delivery assembly of claim 2, wherein the positioning
guide wire lumen includes an angulated section.
4. The stent delivery assembly of claim 2, wherein the positioning
guide wire lumen includes a straight portion and an angulated
portion.
5. The stent delivery assembly of claim 4, wherein the angulated
portion is at an angle relative to the straight portion taken from
the range of angles of 5 degrees to 90 degrees.
6. The stent delivery assembly of claim 1, wherein a stent is
mounted on the expandable member and the stent includes an angled
proximal end for mounting on the expandable member and for
deployment in the side-branch vessel.
7. The stent delivery assembly of claim 1, wherein a side-branch
vessel stent is removeably mounted on the expandable member and
configured for implanting in the side-branch vessel.
8. The stent delivery assembly of claim 7, further comprising: a
main-vessel catheter having a distal end and a proximal end and
having a tracking guide wire lumen extending through at least a
portion thereof; the tracking guide wire lumen of the main-vessel
catheter being sized for receiving the tracking guide wire for
slidable movement therein; an expandable member positioned near the
main-vessel catheter distal end for delivering and implanting a
main-vessel stent adjacent to the side-branch vessel stent; and a
positioning guide wire lumen attached to the outer surface of the
main-vessel catheter and extending over at least a portion of the
surface of the expandable member and sized for slidably receiving
the positioning guide wire, the positioning guide wire lumen
advancing over the positioning guide wire to orient the expandable
member adjacent to, but not in, the side-branch vessel.
9. The stent delivery assembly of claim 1, wherein the positioning
guide wire comprises an integrated stent-positioning guide wire for
accurately positioning a stent, and wherein the side-branch
catheter is configured for rapid exchange so that the catheter can
be unzipped from the integrated stent-positioning guide wire
leaving the guide wire in place for additional interventions.
10. The stent delivery assembly of claim 1, wherein the expandable
member including an angled proximal taper balloon for deploying a
proximal angled stent at the bifurcation site.
11. The stent delivery assembly of claim 1, wherein the side-branch
catheter is a rapid exchange catheter and includes a distal end
opening in the tracking guide wire lumen and a side port opening on
an outer surface of the side-branch catheter so that the tracking
guide wire extends through the side port opening, through the
tracking guide wire lumen, and out the distal end opening, and the
catheter further includes a slit extending from the side port
opening to just proximal of the expandable member so that the
tracking guide wire can be unzipped through the slit during
catheter exchanges.
12. The stent delivery assembly of claim 1, wherein the side-branch
catheter is an over-the-wire catheter and includes a distal end
opening in the tracking guide wire lumen and a proximal opening in
the tracking guide wire lumen so that the tracking guide wire
extends from outside the proximal end opening, through the tracking
guide wire lumen, and out the distal end opening.
13. The stent delivery assembly of claim 8, wherein the main-vessel
catheter is a rapid exchange catheter and includes a distal end
opening in the tracking guide wire lumen and a side port opening on
an outer surface of the main-vessel catheter so that the tracking
guide wire extends through the side port opening on the outer
surface of the main-vessel catheter, through the tracking guide
wire lumen, and out the distal end opening of the main-vessel
catheter, the catheter further including a slit extending from the
side port opening so that the tracking guide wire can be pulled
through the slit during a catheter exchange.
14. The stent delivery assembly of claim 8, wherein the main-vessel
catheter is an over-the-wire catheter and includes a distal end
opening in the tracking guide wire lumen and a proximal opening in
the tracking guide wire lumen so that the tracking guide wire
extends from outside the proximal end opening, through the tracking
guide wire lumen, and out the distal end opening.
15. A proximal angled stent for implanting in a side-branch vessel
adjacent a bifurcation between the side-branch vessel and a main
vessel, comprising: a cylindrical member having a longitudinal
axis, the cylindrical member having a distal end and a proximal
end; the distal end forming a first plane section substantially
transverse to the longitudinal axis; and the proximal end forming a
second plane section having an acute angle relative to the
longitudinal axis, the acute angle being selected to approximately
coincide with an angle formed by the intersection of the
side-branch vessel and the main vessel.
16. The proximal angled stent of claim 15, wherein the stent is
expandable from a first smaller diameter for delivery in a body
lumen to a second expanded diameter by plastically deforming the
stent beyond the elastic limits of the material forming the
stent.
17. The proximal angled stent of claim 15, wherein the stent is
formed from a self-expanding material so that the stent expands
from a first smaller diameter for delivery through a body lumen to
a second implanted diameter in the body lumen.
18. A main-vessel stent for implanting in a main vessel adjacent a
bifurcation, comprising: a cylindrical member having a distal end
and a proximal end and an outer wall surface therebetween; and an
aperture on the outer wall surface being sized and positioned on
the outer wall surface so that when the stent is implanted in the
main vessel, the aperture is aligned with a side-branch vessel
thereby allowing unrestricted blood flow from the main vessel
through to the side-branch vessel.
19. The main-vessel stent of claim 18, wherein the stent is
expandable from a first smaller diameter for delivery in a body
lumen to a second expanded diameter by plastically deforming the
stent beyond the elastic limits of the material forming the
stent.
20. The main-vessel stent of claim 18, wherein the stent is formed
from a self-expanding material so that the stent expands from a
first smaller diameter for delivery through a body lumen to a
second implanted diameter in the body lumen.
21. A method of implanting a proximal angled stent in a side-branch
vessel adjacent to a bifurcation with a main vessel, the method
steps comprising: providing a side-branch catheter assembly having
a tracking guide wire lumen extending through at least a portion
thereof, an expandable member associated with the catheter and
having the proximal angled stent mounted thereon, a
stent-positioning guide wire lumen associated with the expandable
member, a tracking guide wire sized for slidable movement within
the tracking guide wire lumen, and a stent-positioning guide wire
sized for slidable movement within the stent-positioning guide wire
lumen; advancing a distal end of the tracking guide wire into the
side-branch vessel and distal to a target area; advancing the
side-branch catheter along the tracking guide wire and
simultaneously advancing the stent-positioning lumen attached to
the outer proximal surface of the expandable member with the
stent-positioning guide wire contained therein; advancing the
side-branch catheter in the main vessel to a position just proximal
of the side-branch vessel; advancing a distal end of the
stent-positioning guide wire through the main vessel and distal to
the side-branch vessel; further advancing the side-branch catheter
so that the positioning guide wire creates rotation of the
side-branch catheter as the expandable member and proximal angled
stent advance into the side-branch vessel and the side-branch
catheter anchors at the side-branch ostium; aligning the proximal
angled stent across the target area and aligning a proximal end of
the proximal angled stent with the intersection of the side-branch
vessel and the main vessel so that the proximal angled stent does
not extend into the main vessel; inflating the expandable member
thereby expanding and implanting the proximal angled stent at the
target area in the side-branch vessel; deflating the expandable
member and withdrawing the side-branch catheter from the patient;
and withdrawing the tracking and stent-positioning guide wires from
the patient.
22. The method of claim 21, further comprising implanting a
main-vessel stent in the main vessel, including after the step of
withdrawing the side-branch catheter and while the
stent-positioning guide wire remains in position in the main
vessel: providing a main-vessel catheter having a proximal end and
a distal end and a tracking guide wire lumen extending through at
least a portion thereof, an expandable member adjacent the distal
end of the main-vessel catheter and having the main-vessel stent
mounted thereon, a positioning guide wire lumen attached to the
outer surface of the main-vessel catheter and extending over at
least a portion of the surface of the expandable member; providing
a tracking guide wire contained in the stent-positioning guide wire
lumen; inserting the proximal end of the stent-positioning guide
wire into the tracking guide wire lumen; advancing the main-vessel
catheter and the expandable member over the stent-positioning guide
wire in the main vessel until the main-vessel catheter is distal
end about one cm proximal to the side-branch vessel; advancing the
tracking guide wire out of the stent-positioning guide wire lumen
so that the tracking guide wire distal end advances into the
side-branch vessel; manipulating and torquing the tracking and
stent-positioning guide wires until the expandable member and
main-vessel stent are in the main vessel and adjacent the
side-branch vessel; inflating the expandable member and the
main-vessel stent into contact with the main vessel thereby
implanting the stent in the main vessel; deflating the expandable
member and withdrawing the main-vessel catheter from the patient;
and withdrawing the tracking and stent-positioning guide wires from
the patient.
23. The method of claim 22, wherein providing the stent-positioning
guide wire lumen step further comprises providing the
stent-positioning lumen having a straight portion and an angulated
portion.
24. A method of stenting a bifurcated vessel, the method steps
comprising: providing a main-vessel catheter for delivering and
implanting a main-vessel stent having a plurality of stent cells
formed by stent struts; implanting the main-vessel stent in a main
vessel of the bifurcation, the main-vessel stent spanning an
opening to a side-branch vessel and precisely orienting the
main-vessel stent cells with respect to the side-branch ostium so
that subsequent access to the side-branch vessel is not
compromised; withdrawing the main-vessel catheter from the patient;
providing a balloon catheter and advancing the balloon catheter
through the main vessel and through a targeted stent cell and into
the opening of the side-branch vessel; expanding a balloon portion
of the balloon catheter so that the stent struts of the targeted
stent cell adjacent the opening of the side-branch vessel are
deformed thereby forming an opening in main-vessel stent that
substantially corresponds to the opening from the main vessel to
the side-branch vessel; providing a side-branch vessel catheter
having a proximal angled stent mounted on a balloon portion thereof
and advancing the side-branch vessel catheter to the main vessel
and through the opening in the main-vessel stent so that the
side-branch catheter is advanced into the side-branch vessel;
expanding the balloon portion of the side-branch vessel catheter so
that the proximal angled stent on the balloon portion expands into
contact with the side-branch vessel, thereby covering all portions
of the side-branch vessel immediately adjacent the main vessel; and
withdrawing the side-branch vessel catheter from the patient's
vascular system.
25. A stent delivery assembly for treating bifurcated vessels
having a side-branch vessel and a main vessel, comprising: a
main-vessel catheter having a proximal end and a distal end; an
expandable member proximate the distal end of the catheter; a
tracking guide wire lumen extending within at least a portion of
the main-vessel catheter; a tracking guide wire having a distal end
and a proximal end and sized for slidable movement within the
tracking guide wire lumen; a positioning guide wire lumen having a
portion thereof attached to the expandable member and adapted to
receive for slidable engagement a positioning guide wire, the
positioning guide wire having a distal end and a proximal end; the
proximal ends of the tracking and positioning guide wires extend
out of the patient and can be manipulated so that the distal end of
the positioning guide wire is advanced in the main vessel distal to
the side-branch vessel, and the distal end of the tracking guide
wire is advanced into the side-branch vessel.
26. The stent delivery assembly of claim 25, wherein the portion of
positioning guide wire lumen attached to the expandable member
extends along the expandable member with a stent mounted over the
portion of positioning guide wire lumen.
27. The stent delivery assembly of claim 25, wherein a ramp is
associated with a distal end of the positioning guide wire lumen to
assist moving the positioning guide wire radially outwardly.
28. The stent delivery assembly of claim 25, wherein the portion of
positioning guide wire lumen extends along substantially all of the
expandable member.
29. The stent delivery assembly of claim 25, wherein the portion of
positioning guide wire lumen includes a distal section attached to
the distal end of the catheter.
30. The stent delivery assembly of claim 25, wherein the portion of
positioning guide wire lumen is angled and extends along the
expandable member.
31. The stent delivery assembly of claim 25, wherein a main-vessel
stent is mounted on the expandable member and over the portion of
positioning guide wire lumen attached to the balloon.
32. The stent delivery assembly of claim 29, wherein the portion of
the positioning guide wire lumen attached to the expandable member
includes a distal section biased outwardly to spring away from the
expandable member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to stent deployment assemblies for use
at a bifurcation and, more particularly, a catheter assembly for
implanting one or more stents for repairing bifurcations, the
aorto-ostium, and bifurcated blood vessels that are diseased, and a
method and apparatus for delivery and implantation.
[0003] 2. Prior Art
[0004] Stents conventionally repair blood vessels that are diseased
and are generally hollow and cylindrical in shape and have terminal
ends that are generally perpendicular to its longitudinal axis. In
use, the conventional stent is positioned at the diseased area of a
vessel and, after placement, the stent provides an unobstructed
pathway for blood flow.
[0005] Repair of vessels that are diseased at a bifurcation is
particularly challenging since the stent must overlay the entire
diseased area at the bifurcation, yet not itself compromise blood
flow. Therefore, the stent must, without compromising blood flow,
overlay the entire circumference of the ostium to a diseased
portion and extend to a point within and beyond the diseased
portion. Where the stent does not overlay the entire circumference
of the ostium to the diseased portion, the stent fails to
completely repair the bifurcated vessel. Where the stent overlays
the entire circumference of the ostium to the diseased portion, yet
extends into the junction comprising the bifurcation, the diseased
area is repaired, but blood flow may be compromised in other
portions of the bifurcation. Unapposed stent elements may promote
lumen compromise during neointimalization and healing, producing
restenosis and requiring further procedures. Moreover, by extending
into the junction comprising the bifurcation, the stent may block
access to portions of the bifurcated vessel that require
performance of further interventional procedures. Similar problems
are encountered when vessels are diseased at their angled origin
from the aorta as in the ostium of a right coronary or a vein
graft. In this circumstance, a stent overlying the entire
circumference of the ostium extends back into the aorta, creating
problems, including those for repeat catheter access to the vessel
involved in further interventional procedures.
[0006] Conventional stents are designed to repair areas of blood
vessels that are removed from bifurcations and, since a
conventional stent generally terminates at right angles to its
longitudinal axis, the use of conventional stents in the region of
a vessel bifurcation may result in blocking blood flow of a side
branch or fail to repair the bifurcation to the fullest extent
necessary. The conventional stent might be placed so that a portion
of the stent extends into the pathway of blood flow to a side
branch of the bifurcation or extend so far as to completely cover
the path of blood flow in a side branch. The conventional stent
might alternatively be placed proximal to, but not entirely
overlaying the circumference of the ostium to the diseased portion.
Such a position of the conventional stent results in a bifurcation
that is not completely repaired. The only conceivable situation
that the conventional stent, having right-angled terminal ends,
could be placed where the entire circumference of the ostium is
repaired without compromising blood flow, is where the bifurcation
is formed of right angles. 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 ends of the conventional stent overlying the
entire circumference of the ostium to the diseased portion without
extending into a side branch, thereby completely repairing the
right-angled bifurcation.
[0007] 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 the
entire circumference of the ostium to a diseased portion, yet does
not extend into the junction comprising the bifurcation, may be
employed. Such a stent would have the advantage of completely
repairing the vessel at the bifurcation without obstructing blood
flow in other portions of the bifurcation. In addition, such a
stent would allow access to all portions of the bifurcated vessel
should further interventional treatment be necessary. In a
situation involving disease in the origin of an angulated
aorto-ostial vessel, such a stent would have the advantage of
completely repairing the vessel origin without protruding into the
aorta or complicating repeat access.
[0008] In addition to the problems encountered by using the prior
art stents to treat bifurcations, the delivery platform for
implanting such stents has presented numerous problems. For
example, a conventional stent is implanted in the main vessel so
that a portion of the stent is across the side branch, so that
stenting of the side branch must occur through the main-vessel
stent struts. In this method, commonly referred to in the art as
the "monoclonal antibody" approach, the main-vessel stent struts
must be spread apart to form an opening to the side-branch vessel
and then a catheter with a stent is delivered through the opening.
The cell to be spread apart must be randomly and blindly selected
by recrossing the deployed stent with a wire. The drawback with
this approach is 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 the appropriate 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. The drawback with this approach is that there is no
way to tell if the main-vessel stent struts have been properly
oriented and spread apart to provide a clear opening for stenting
the side-branch vessel.
[0009] 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
vessel. A dilatation is then performed in the main vessel to open
and stretch the stent struts extending across the lumen from the
side-branch vessel. Thereafter, the main-vessel stent is implanted
so that its proximal end overlaps with the side-branch 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. Furthermore the deployed stent must be
recrossed with a wire blindly and arbitrarily selecting a
particular stent cell. When dilating the main vessel stretching the
stent struts is therefore random, leaving the possibility of
restricted access, incomplete lumen dilatation, and major stent
distortion.
[0010] In another prior art device and 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 ostium. 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 distal 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 a distal portion of the main
vessel, and a third stent, or a proximal stent, in the main vessel
just proximal to the bifurcation.
[0011] All of the foregoing stent deployment assemblies suffer from
the same problems and limitations. Typically, there is uncovered
intimal surface segments on the main vessel and side-branch vessels
between the stented segments. An uncovered flap or fold in the
intima or plaque will invite a "snowplow" effect, representing a
substantial risk for subacute 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, making successful placement nearly
impossible. 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.
[0012] 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
distal segment, but not extending into the ostium of the distal
side-branch, may be difficult or impossible. The present invention
also offers a solution to this problem.
[0013] References to distal and proximal herein shall mean: the
proximal direction is moving away from or out of the patient and
distal is moving toward or into the patient. These definitions will
apply with reference to body lumens and apparatus, such as
catheters, guide wires, and stents.
SUMMARY OF THE INVENTION
[0014] The invention provides for improved stent designs and stent
delivery assemblies for repairing a main vessel and side-branch
vessel forming a bifurcation, without compromising blood flow in
other portions of the bifurcation, thereby allowing access to all
portions of the bifurcated vessels should further interventional
treatment be necessary. In addition, it provides an improved stent
design and stent delivery system for repairing disease confined to
the aorto-ostium of a vessel without protrusion into the aorta. The
stent delivery assemblies of the invention all share the novel
feature of containing, in addition to a tracking guide wire, a
second positioning wire which affects rotation and precise
positioning of the assembly for deployment of the stent.
[0015] The present invention includes a proximal angled stent for
implanting in a side-branch vessel adjacent to a bifurcation. The
cylindrical member can have substantially any outer wall surface
typical of conventional stents used, for example, in the coronary
arteries. The cylindrical member of the proximal angled stent has a
distal end forming a first plane section that is substantially
transverse to the longitudinal axis of the stent. The proximal end
of the stent forms a second plane section that is at an angle,
preferably an acute angle, relative to the longitudinal axis of the
stent. The acute angle is selected to approximately coincide with
the angle formed by the intersection of the side-branch vessel and
the main vessel so that no portion of the stented area in the
side-branch vessel is left uncovered, and no portion of the
proximal angled stent extends into the main vessel.
[0016] A second stent is provided for implanting in the main vessel
adjacent to a bifurcation in which a cylindrical member has distal
and proximal ends and an outer wall surface therebetween, which can
typically be similar to the outer wall surface of stents used in
the coronary arteries. An aperture is formed in the outer wall
surface of the apertured stent and is sized and positioned on the
outer wall surface so that when the apertured stent is implanted in
the main vessel, the aperture is aligned with the side-branch
vessel and the proximal angled stent in the side-branch vessel,
providing unrestricted blood flow from the main vessel through to
the side-branch vessel. Deployment of the angled and apertured
stents is accomplished by a novel stent delivery system adapted
specifically for treating bifurcated vessels.
[0017] In one embodiment for implanting the proximal angled stent,
a side-branch catheter is provided in which a tracking guide wire
lumen extends within at least a portion of the side-branch
catheter, being designed to be either an over-the-wire or rapid
exchange-type catheter. An expandable member is disposed at the
distal end of the side-branch catheter. A tracking guide wire is
provided for slidable movement within the tracking guide wire
lumen. A positioning guide wire lumen is associated with the
catheter and the expandable member, such that a portion of the
positioning guide wire lumen is on the outer surface of the
catheter and it approaches the proximal end of the outer surface of
the expandable member. A stent-positioning guide wire is provided
for slidable movement within the positioning lumen. The proximal
ends of the tracking and stent-positioning guide wires extend out
of the patient and can be simultaneously manipulated so that the
distal end of the stent-positioning guide wire is advanced in the
main vessel distal to a side-branch vessel, and the distal end of
the tracking guide wire is advanced into the side-branch vessel
distal to the target area. In a preferred embodiment, the
stent-positioning guide wire lumen includes an angulated section so
that the stent-positioning guide wire advanced in the main vessel
distal to the side-branch vessel results in rotation causing the
proximal angled stent to assume the correct position in the
side-branch vessel. The positioning lumen functions to orient the
stent-positioning guide wire to rotate or torque the side-branch
catheter to properly align and position the proximal angled stent
in the side-branch vessel.
[0018] The side-branch catheter assembly is capable of delivering
the proximal angled stent, mounted on the expandable member, in the
side-branch vessel. The side-branch catheter could also be
configured for delivering a self-expanding proximal angled
stent.
[0019] The stent delivery system of the present invention further
includes a main-vessel catheter for delivering a stent in the main
vessel after the side-branch vessel has been stented. The
main-vessel catheter includes a tracking guide wire lumen extending
through at least a portion thereof, and adapted for receiving a
tracking guide wire for slidable movement therein. An expandable
member is positioned near the main-vessel catheter distal end for
delivering and implanting a main-vessel (apertured) stent in the
main vessel. The main-vessel stent includes an aperture on its
outer surface which aligns with the side-branch vessel. A
positioning guide wire lumen is associated with the expandable
member, and is sized for slidably receiving the stent-positioning
guide wire. The stent-positioning guide wire slides within the
positioning guide wire lumen to orient the expandable member so
that it is positioned adjacent to, but not in, the side-branch
vessel with the stent aperture facing the side-branch ostium.
[0020] In a preferred embodiment, both the side-branch catheter and
main-vessel catheter assemblies include the so-called rapid
exchange catheter features which are easily exchangeable for other
catheters while the tracking and positioning guide wires remain
positioned in the side-branch vessel and the main vessel,
respectively. In an alternate embodiment, both catheters may be of
the "over-the-wire" type.
[0021] The present invention further includes a method for
delivering the proximal angled and the main-vessel (apertured)
stents in the bifurcated vessel. In a preferred embodiment of the
side-branch catheter system (side-branch catheter plus proximal
angled stent), the distal end of the tracking guide wire is
advanced into the side-branch vessel and distal to the target area.
The side-branch catheter is then advanced along the tracking guide
wire until the distal end of the catheter is just proximal of
entering the side-branch. The distal end of the integrated,
stent-positioning guide wire is then advanced by the physician
pushing the guide wire from outside the body. The distal end of the
stent-positioning wire travels through the positioning guide wire
lumen and passes close to the proximal end of the proximal angled
stent and expandable member and exits the lumen. The wire is
advanced in the main vessel until the distal end is distal to the
side-branch vessel. The catheter is then advanced into the side
branch until resistance is felt from the stent-positioning guide
wire pushing up against the ostium of the side-branch vessel
causing the proximal angled stent to rotate into position and
arresting its advancement at the ostium. Thereafter, the proximal
angled stent, mounted on the expandable member, is aligned across
the target area and the angled proximal end of the stent is aligned
at the intersection of the side-branch vessel and the main vessel
(the ostium of the side-branch vessel) so that the stent completely
covers the target area in the side-branch vessel, yet does not
extend into the main vessel, thereby blocking blood flow. The
expandable member is expanded thereby expanding and implanting the
proximal angled stent in the side-branch vessel. The positioning
wire prevents forward movement of the expandable member and
proximal angled stent during inflation. Thereafter, the expandable
member is deflated and the side-branch catheter assembly is
withdrawn from the patient in a known rapid-exchange manner. In
this embodiment, the side-branch catheter is designed so that both
the side-branch tracking guide wire and main-vessel positioning
guide wire can be left in their respective vessels should
sequential or simultaneous high pressure balloon inflation be
required in each of the vessels in order to complete the stenting
procedure. In other words, the integrated positioning wire can be
unzipped from the proximal 100 cm of the catheter thereby allowing
it to act as a rapid exchange wire. Preferably, high pressure
balloons are inflated simultaneously in the main vessel and
proximal angled stents in order to avoid deforming one stent by
unopposed balloon inflation within the other one. This additional
step of high pressure balloon inflation is a matter of physician
choice. A further advantage of this embodiment is that by waiting
to advance the integrated stent-positioning wire out of catheter
only when the catheter distal end is near the target area, wire
wrapping, encountered in an embodiment utilizing two non-integrated
guide wires, is avoided. Utilizing this preferred method, the
side-branch vessel can be stented without the need for stenting the
main vessel.
[0022] In an aorto-ostial application of the side-branch catheter
assembly (side-branch catheter plus proximal angulated stent), the
positioning wire is advanced into the aortic root while the
tracking wire is advanced into the right coronary or vein graft
whose angulated origin is to be stented. After advancement of the
proximal-angled stent, mounted on the expanding member, it is
aligned across the target area and the angled proximal end of the
stent is aligned at the ostium.
[0023] In the event that the main vessel is to be stented (with the
stent placed across the bifurcation site), the proximal end of the
main-vessel guide wire is inserted into the distal end of the guide
wire lumen of the main-vessel catheter. The side-branch wire would
be removed from the side branch at this time. The main-vessel
catheter would then be advanced into the body until the catheter is
within one cm or so of the target site. The distal end of the
second (integrated, stent-positioning) guide wire, which resides in
the main-vessel catheter during delivery to the main vessel, is
then advanced by having the physician push the positioning wire
from outside the body. The distal end of the stent-positioning wire
travels through the positioning guide wire lumen and passes
underneath the proximal half of the stent until it exits at the
site of the stent aperture or a designated stent cell where an
aperture can be formed. The catheter is then advanced distally
until resistance is felt from the stent-positioning guide wire
pushing up against the ostium of the side-branch vessel indicating
that the stent aperture is correctly facing the side-branch vessel
ostium and is aligned with the proximal end of the proximal angled
stent. Thereafter, the expandable member on the main-vessel
catheter is inflated, thereby expanding and implanting the
main-vessel stent into contact with the main vessel, with the
aperture in the stent providing a flow path for the blood from the
main vessel through to the side-branch vessel without any
obstructions. The expandable member is deflated and the main-vessel
catheter is removed from the body. The main-vessel catheter is
designed so that both the main-vessel guide wire and side-branch
wire can be left in their respective vessels should sequential or
simultaneous high pressure balloon inflation be required in each of
the vessels in order to complete the stenting procedure. The
presence of the stent-positioning wire in the stent aperture
permits catheter access through this aperture into the side-branch
vessel for balloon inflation to smooth out the aperture in the
main-vessel stent. This additional step is a matter of physician
choice.
[0024] Utilizing this preferred method, the main vessel can be
stented without the need for stenting the side-branch vessel. An
advantage of this embodiment is that a major side branch, not
diseased and requiring treatment, exiting from a main vessel
requiring stenting, may be protected by the positioning wire while
the main vessel is stented. If "snowplowing" compromise or closure
of the side-branch vessel occurs with main-vessel stenting, then
access is already present and guaranteed for stenting of the
side-branch vessel over the wire already in place in the manner
described above. This will allow confident stenting of a main
vessel segment containing a major side branch. In this usage, only
if compromise or occlusion of the side branch occurs, will
additional stenting of the side branch be required.
[0025] In an alternative embodiment, a main-vessel stent that does
not have an aperture on its outer surface is mounted on the
main-vessel catheter and is implanted in the main vessel so that it
spans the opening to the side-branch vessel. Thereafter, a balloon
catheter is inserted through a targeted (non-random) stent cell of
the main-vessel stent, which is centered precisely facing the
side-branch ostium, so that the balloon partially extends into the
side-branch vessel. This balloon has tracked over the positioning
wire which has been left in place through the targeted stent cell
during and after deployment of the main vessel stent. The balloon
is expanded, forming an opening through the stent struts that
corresponds to the opening of the side-branch vessel, providing a
blood-flow path through the main vessel and main-vessel stent and
into the side-branch vessel. A proximal angled stent mounted on a
side-branch catheter is then advanced through the main-vessel stent
and the opening formed in the targeted stent cell through to the
side-branch vessel. The proximal angled stent is expanded and
implanted in the side-branch vessel so that all portions of the
side-branch vessel are covered by the stent in the area of the
bifurcation. After the main-vessel stent and the side-branch vessel
proximal angled stent are implanted, an uncompromised blood-flow
path is formed from the main vessel through the main-vessel stent
and opening into the side-branch vessel, and through the
side-branch vessel proximal angled stent.
[0026] In another alternative embodiment, a stent having a distal
angle is implanted in the main vessel. In portions of the main
vessel having disease that approaches and is directly adjacent to
the side-branch vessel, a distal angle stent is implanted using the
novel catheter of the present invention so that the stent covers
the diseased area, but does not jail or cover the opening to the
side-branch vessel.
[0027] In another alternative embodiment, a Y-shaped catheter and
Y-shaped stent are provided for stenting a bifurcated vessel. In
this embodiment, a dual balloon catheter has a Y-shaped stent
mounted on the balloons and the balloons are positioned side by
side for easier delivery. The balloons are normally biased apart,
but are restrained and held together to provide a low profile
during delivery of the stent. A guide wire is first positioned in a
main vessel at a point distal to the bifurcation. A second guide
wire is retained in the catheter in a second guide wire lumen while
the catheter is advanced over the tracking guide wire so that the
balloons and stent are distal to the bifurcation. The tracking
guide wire is then withdrawn proximally thereby releasing the
balloons which spring apart. The catheter is withdrawn proximally
until it is proximal to the bifurcation. As the catheter is
withdrawn proximally, one of the two guide wires is left in the
main vessel. The other guide wire is then advanced into the
side-branch vessel. The catheter is then advanced over both guide
wires until the balloons and stent are anchored in the bifurcation.
The balloons are inflated and the stent expanded and implanted in
the bifurcation.
[0028] In another embodiment two apertured stents are implanted to
cover the bifurcated vessels. A main-vessel stent has a cylindrical
shape having a heavy cell density on the distal half and light cell
density on the proximal half, and an aperture on its outer surface
at the junction at these two halves. A main-vessel stent is first
implanted in the main vessel so that its aperture aligns with the
ostium of the side-branch vessel, thereby covering the main vessel
proximally with light cell density and distally with heavy cell
density. A second main-vessel stent is then implanted over a
tracking wire into the side branch so that the heavy cell density
portion of the stent is implanted in the side-branch vessel, the
light cell density is implanted in the main vessel and overlaps the
light cell density of the proximal end of the main-vessel stent,
and the aperture faces the main vessel as it departs from the side
branch. Combined densities of proximal light cell portions proximal
to the bifurcation are similar to the heavy cell densities in each
limb distal to the bifurcation. Respective apertures of each of the
two main-vessel stents are aligned with the respective ostia of
both limbs of the bifurcation (main vessel and side branch).
[0029] Other features and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, which illustrate, by
way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] 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.
[0031] 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
proximal portion of the main vessel next to the branch stent, with
interrupted placement of a third stent implanted more distally in
the main vessel.
[0032] 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 distal to the bifurcation.
[0033] 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.
[0034] FIG. 5A is a perspective view of a stent of the present
invention having an angled proximal end.
[0035] FIG. 5B is a side elevational view of the proximal angled
stent of FIG. 5A depicting the distal end being transverse to the
longitudinal axis of the stent, and the proximal end at an angle of
less than 90.degree..
[0036] FIG. 5C is an elevational view of a bifurcation in which a
prior art stent is implanted in the side-branch vessel.
[0037] FIG. 5D 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.
[0038] FIG. 5E is an elevational view of a bifurcation in which the
proximal angled stent of the present invention, as depicted in
FIGS. 5A and 5B, is implanted in the side-branch vessel.
[0039] FIG. 6A is a perspective view depicting the main-vessel
stent of the present invention in which an aperture is formed on
the outer surface of at least a portion of the stent.
[0040] FIG. 6B is a side elevational view of the main-vessel stent
of FIG. 6A.
[0041] FIG. 7A is an elevational view, partially in section, of a
side-branch catheter assembly depicting the distal end of the
catheter with the expandable member and the second guide wire lumen
attached thereto, for receiving the integrated stent-positioning
guide wire, while the tracking guide wire is received by the main
guide wire lumen.
[0042] FIG. 7B is an elevational view, partially in section, of the
catheter assembly of FIG. 7A, in which the stent positioning guide
wire is advanced out of the catheter.
[0043] FIG. 8 is an elevational view, partially in section, of a
side-branch catheter assembly depicting an expandable balloon
having an angled proximal portion corresponding to the angle of the
proximal angled stent.
[0044] FIG. 9A is an elevational view of a bifurcated vessel in
which a side-branch tracking guide wire has been advanced into a
side-branch vessel, with the stent-positioning guide wire remaining
within the catheter until the catheter assembly is just proximal to
the side-branch vessel.
[0045] FIG. 9B is an elevational view of a bifurcation in which a
side-branch tracking guide wire has been advanced through the
patient's vascular system into a side branch, and a
stent-positioning guide wire has been advanced through the
patient's vascular system and into the main vessel distal to the
ostium of the side-branch vessel.
[0046] FIG. 10A is an elevational view of a bifurcation in which
the side-branch catheter assembly has been advanced in the
patient's vasculature so that the proximal angled stent mounted on
the expandable member is positioned in the target area of the
side-branch vessel.
[0047] FIG. 10B is an elevational view of the side-branch catheter
assembly of FIG. 10A in which the proximal angled stent has been
expanded by the balloon portion of the catheter in the side-branch
vessel.
[0048] FIGS. 11A-11D are partial elevational views in which the
side-branch catheter assembly of FIG. 10A is used to implant the
proximal angled stent in the side-branch vessel where the proximal
angled stent is rotated to be properly aligned for implanting in
the vessel.
[0049] FIGS. 12A-12C depict an elevational view, partially in
section, of a main-vessel catheter assembly in which the main
vessel stent has an aperture on its outer surface.
[0050] FIGS. 12D-12F depict an elevational view, partially in
section, of the main-vessel catheter of FIGS. 12A-12C with a ramp
to help orient and advance the guide wire through the aperture in
the main-vessel stent.
[0051] FIGS. 12G-12I depict an elevational view, partially in
section, of an alternative embodiment of the main-vessel catheter
of FIGS. 12A-12C in which the guide wire lumen is angled to pass
under the stent and exit through the stent aperture.
[0052] FIGS. 12J-12L depict an elevational view, partially in
section, of an alternative embodiment of the main-vessel catheter
of FIGS. 12A-12C in which a portion of the guide wire lumen passes
under the stent.
[0053] FIGS. 13A-13E are elevational views, partially in section,
depicting the main-vessel catheter assembly of FIG. 12A and the
main-vessel stent in which two guide wires are used to correctly
position the main vessel stent so that the aperture in the stent is
aligned with the side-branch vessel.
[0054] FIG. 14 is an elevational view of a bifurcated vessel in
which the proximal angled stent is implanted in the side-branch
vessel and a main vessel stent is implanted in the main vessel.
[0055] FIG. 15 is a perspective view of the main-vessel stent of
the present invention for deployment in the main vessel, where a
targeted stent cell provides an opening through which a guide wire
can pass.
[0056] FIGS. 16A-16D are elevational views, partially in section,
of a main vessel catheter having the main vessel stent of FIG. 15
mounted thereon, and its relationship to the guide wire for
advancing through a targeted stent cell.
[0057] FIG. 17 is an elevational view of a bifurcation in which a
main-vessel stent is positioned in a main vessel so that it spans
the opening to the side-branch vessel.
[0058] FIG. 18 is an elevational view of a bifurcation in which a
main-vessel stent is implanted in the main vessel and a balloon
catheter is partially inserted into a side-branch vessel to form an
opening through the targeted stent cell of the main stent.
[0059] FIGS. 19A-19C are elevational views of a bifurcation in
which a main-vessel stent is first implanted in the main vessel and
a catheter assembly next deploys a proximal angled stent in a
side-branch vessel.
[0060] FIGS. 19D and 19E are cross-sectional views looking down the
side-branch vessel at an expanded main vessel prior art stent in
which a random, sub-optimal stent cell was entered and
expanded.
[0061] FIG. 19F is a cross-sectional view looking down the
side-branch vessel at an expanded main-vessel stent of the
invention in which proper targeted stent cell was entered and
expanded.
[0062] FIG. 20A is an elevational view, partially in section,
depicting a main vessel catheter in which the main vessel stent is
mounted over a positioning guide wire lumen.
[0063] FIG. 20B is an elevational view, partially in section, of a
main vessel catheter depicting the main vessel stent mounted over a
section of the positioning guide wire lumen, with a distal portion
of the guide wire lumen associated with the distal tip of the
catheter.
[0064] FIG. 20C is an elevational view, partially in section, of
the catheter of FIG. 20B depicting the positioning guide wire
advanced out of the positioning guide wire lumen.
[0065] FIG. 20D is an elevational view, partially in section,
depicting a main-vessel stent implanted in the main vessel without
jailing or covering the side-branch vessel.
[0066] FIG. 20E is an elevational view, partially in section,
depicting the main-vessel catheter of FIG. 20A having a ramp to
assist in positioning the guide wire.
[0067] FIG. 20F is an elevational view, partially in section, of a
distal angled stent being implanted in the main vessel without
jailing the side-branch vessel.
[0068] FIGS. 21 and 22 are elevational views, partially in section,
depicting an alternative embodiment of the main-vessel catheter of
FIG. 20B in which the distal end of the guide wire lumen springs
away from the expandable balloon. FIGS. 23A-23B, 24A-24B, 25A-25B,
and 26A-26B, are elevational views of various bifurcations which
are indicated for receiving main vessel and side-branch vessel
stents deployed by the catheters of the present invention.
[0069] FIG. 27A is an elevational view, partially in section,
depicting an alternative embodiment in which a Y-shaped catheter
assembly deploys a Y-shaped stent in the bifurcation.
[0070] FIG. 27B is an elevational view depicting an alternative
embodiment in which a dual balloon catheter assembly deploys a
Y-shaped stent in the bifurcation.
[0071] FIG. 28 is an elevational view depicting the Y-shaped
catheter assembly of FIG. 27A in which the stent is mounted on the
balloon portions of the catheter.
[0072] FIG. 29A is an elevational view, partially in section of a
bifurcation in which the Y-shaped catheter of FIG. 27A is
delivering the stent in the bifurcated area, tracking over the wire
that joins the two tips together.
[0073] FIG. 29B is an elevational view, partially in section, of a
bifurcation in which the delivered Y-shaped balloon components have
been released and spread apart by withdrawal of the tracking wire
from the other balloon tip lumen.
[0074] FIG. 29C is an elevational view, partially in section, of
the Y-shaped delivery catheter of FIG. 27A in which the Y-shaped
balloon has been withdrawn proximal to the bifurcation, leaving the
first wire in the right branch.
[0075] FIG. 30 is an elevational view, partially in section, of the
Y-shaped delivery catheter of FIG. 27A in which the second guide
wire is advanced into the left branch.
[0076] FIG. 31 is an elevational view depicting the Y-shaped
atheter of FIG. 27A in which the Y-shaped stent is implanted in the
side branch and main vessels of the bifurcation.
[0077] FIG. 32 is an elevational view, partially in section,
depicting the Y-shaped catheter assembly of FIG. 27A in which the
Y-shaped stent has been implanted and the balloon portions of the
catheter have been deflated.
[0078] FIG. 33 is an elevational view depicting a bifurcated vessel
in which the catheter of FIG. 27A has been withdrawn after
implanting the Y-shaped stent.
[0079] FIG. 34 is an elevational view depicting a modified stent
having an aperture in its sidewall and in which half of the stent
has a heavy stent cell density while the other half of the stent
has a light stent cell density.
[0080] FIG. 35 is an elevational view depicting the stent of FIG.
35 combined to form a stent having a heavy stent cell density in
all portions.
[0081] FIG. 36A is an elevational view depicting a bifurcation, in
which the stent of FIG. 35 has been implanted so that the aperture
corresponds to the side-branch vessel and the stent is implanted in
the main vessel.
[0082] FIG. 36B is an elevational view depicting a bifurcating
vessel in which the stent of FIG. 34 has been implanted so that the
heavy stent cell density is in the side-branch vessel and the light
cell density is in the main vessel. The aperture corresponds to the
continuing lumen of the main vessel.
[0083] FIG. 36C is an elevational view depicting a bifurcated
vessel in which two stents of FIG. 34 have been implanted in the
side-branch vessel and the main vessel respectively so that the
light stent cell density of each overlaps with the light cell
density of the other thereby creating cell density proximal to the
bifurcation similar to the heavy cell density present in each limb
distal to the bifurcation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0084] The present invention includes an assembly and method for
treating bifurcations in, for example, the coronary arteries,
veins, arteries, and other vessels in the body. 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 ostium of the bifurcation, and a second stent is
implanted in the main vessel, across the side-branch ostium. 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.
[0085] Referring to FIG. 2, three prior art stents are required to
stent the bifurcation. 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 an
uncovered luminal area.
[0086] All of the prior art devices depicted in FIGS. 1-4 have
various drawbacks which have been solved by the present
invention.
[0087] In one preferred embodiment of the present invention, as
depicted in FIGS. 5A, 5B and 5E, proximal angled stent 10 is
configured for deployment in side-branch vessel 5. Proximal angled
stent 10 includes a cylindrical member 11 having longitudinal axis
12 which is an imaginary axis extending through cylindrical member
11. Distal end 13 and proximal end 14 define the length of
cylindrical member 11. First plane section 15 is defined by a plane
section through distal end 13 of the cylindrical member, and second
plane section 16 is defined by a plane section through proximal end
14 of the cylindrical member. Second plane section 16 defines acute
angle 18, which is the angle between second plane section 16 and
longitudinal axis 12.
[0088] In treating side-branch vessel 5, if a prior art stent is
used in which there is no acute angle at one end of the stent to
match the angle of the bifurcation, a condition as depicted in
FIGS. 5C and 5D will occur. That is, a stent deployed in
side-branch vessel 5 will leave a portion of the side-branch vessel
exposed, or as depicted in 5D, a portion of the stent will extend
into main-vessel 6. As depicted in FIG. 5E, proximal angled stent
10 of the present invention has an acute angle 18 that approximates
the angle formed by the bifurcation 4 of side-branch vessel 5 and
main-vessel 6. Thus, acute angle 18 is intended to approximate the
angle formed by the intersection of side-branch 5 and main-vessel
6. The angle between side-branch vessel 5 and main-vessel 6 will
vary for each application, and for purposes of the present
invention, should be less than 90.degree.. If there is a 90.degree.
angle between the side-branch vessel and the main vessel, a
conventional stent having ends that are transverse to the stent
longitudinal axis, would be suitable for stenting the side-branch
vessel.
[0089] The proximal angled stent can be implanted in the
side-branch vessel to treat a number of angulated ostial lesions
including, but not limited to, the following:
[0090] 1. The ostium of a left anterior descending artery (LAD)
where there is a circumflex or trifurcation vessel at less than
90.degree. in its departure from the LAD.
[0091] 2. The ostium of the circumflex artery or a trifurcation in
a similar situation as number 1.
[0092] 3. The ostium of a sizeable diagonal.
[0093] 4. The LAD just distal to, but sparing, the origin of a
diagonal.
[0094] 5. The ostium of a circumflex marginal artery with an
angulated take-off.
[0095] 6. Disease in the circumflex artery just distal to a
marginal take-off, but sparing that take-off.
[0096] 7. The aorta-ostium of a right coronary artery with an
angled take-off.
[0097] 8. The origin of an angulated posterior descending
artery.
[0098] 9. The origin of an LV extension branch just at and beyond
the crux, sparing the posterior descending artery.
[0099] 10. The ostium of an angulated vein graft origin.
[0100] 11. Any of many of the above locations in conjunction with
involvement of the bifurcation and an alternate vessel.
[0101] The proximal angled stent of the present invention typically
can be used as a solo device to treat the foregoing indications, or
it can be used in conjunction with the main vessel stent described
herein for stenting the bifurcation.
[0102] In keeping with the invention, as depicted in FIGS. 6A and
6B, main-vessel stent 20 is configured for deployment in
main-vessel 6. Main-vessel stent 20 includes cylindrical member 21
having distal end 22 and proximal end 23. Main-vessel stent 20
includes outer wall surface 24 which extends between distal end 22
and proximal end 23 and incorporates aperture 25 on outer wall
surface 24. Aperture 25 is configured so that, upon expansion, it
approximates the diameter of expanded proximal end 14 of proximal
angled stent 10. When main-vessel stent 20 is implanted and
expanded into contact with main-vessel 6, aperture 25 is aligned
with side-branch vessel 5 and proximal end 14 of proximal angled
stent, thereby providing an unrestricted blood flow path from the
side-branch vessel to the main vessel. Unlike the prior art, the
main-vessel catheter allows selection and positioning of an
aperture at the side-branch ostium. Furthermore, it provides for
the positioning of a guide wire during main-vessel stent deployment
which can be used for additional intervention if necessary. In the
prior art techniques access to a side-branch is through a randomly
selected stent element ("cell") and is only possible after
deployment of the stent. The precise positioning of aperture 25 is
optional and aperture 25 could be positioned either closer to the
proximal or distal end of stent 20.
[0103] Proximal angled stent 10 and main-vessel stent 20 can be
formed from any of a number of materials including, but not limited
to, stainless steel alloys, nickel-titanium alloys (the NiTi can be
either shape memory or pseudoelastic), tantalum, tungsten, or any
number of polymer materials. Such materials of manufacture are
known in the art. Further, proximal angled stent 10 and main-vessel
stent 20 can have virtually any pattern known to prior art stents.
In a preferred configuration, proximal angled stent 10 and
main-vessel stent 20 are formed from a stainless steel material and
have a plurality of cylindrical elements connected by connecting
members, wherein the cylindrical elements have an undulating or
serpentine pattern. Such a stent is disclosed in U.S. Pat. No.
5,514,154 and is manufactured and sold in Europe only, at this
time, by Advanced Cardiovascular Systems, Inc., Santa Clara, Calif.
The stent is sold under the tradename MultiLink.RTM. Stent. Such
stents can be modified to include the novel features of proximal
angled stent 10 (the angulation) and main-vessel stent 20 (the
aperture).
[0104] Proximal angled stent 10 and main-vessel stent 20 preferably
are balloon-expandable stents that are mounted on a balloon portion
of a catheter and crimped tightly onto the balloon to provide a low
profile delivery diameter. After the catheter is positioned so that
the stent and the balloon portion of the catheter are positioned
either in the side-branch or the main vessel, the balloon is
expanded, thereby expanding the stent beyond its elastic limit into
contact with the vessel. Thereafter, the balloon is deflated and
the balloon and catheter are withdrawn from the vessel, leaving the
stent implanted. Deployment of the angled and main-vessel stents is
accomplished by a novel stent delivery system adapted specifically
for treating bifurcated vessels. The proximal angled stent and the
main-vessel stent could be made to be either balloon expandable or
self-expanding.
[0105] In one preferred embodiment for delivering the novel stents
of the present invention, as depicted in FIGS. 7A and 7B,
side-branch stent delivery assembly 30 is provided and includes
side-branch catheter 31. The side-branch catheter includes distal
end 32 which is configured for delivery in the patient's
vasculature and proximal end 33 which remains outside the patient.
First guide wire lumen 34A extends through at least a portion of
side-branch catheter 31 depending on the type of catheter desired
for a particular application. First guide wire lumen 34A preferably
is defined by distal end 34B and side port 34C, which is typical of
the so-called rapid-exchange-type catheters. Typically, a slit (not
shown) extends from side port 34C to just proximal of the balloon
portion of the catheter so that the catheter can be rapidly
exchanged during a medical procedure, as is known.
[0106] The expandable member 35, which is typically a
non-distensible balloon, has a first compressed diameter for
delivery through the vascular system, and a second expanded
diameter for implanting a stent. The expandable member 35 is
positioned near distal end 32, and in any event between distal end
32 of first catheter 31 and side port 34C.
[0107] Referring to FIGS. 7A and 7B, tracking guide wire 36A,
distal end 36B, and proximal end 36C all extend through first guide
wire lumen 34A. Tracking guide wire 36A preferably is a stiff wire
having a diameter of 0.014 inch, but can have a different diameter
and stiffness as required for a particular application. A
particularly suitable guide wire can include those manufactured and
sold under the tradenames Sport.RTM. and Ironman.RTM., manufactured
by Advanced Cardiovascular Systems, Inc., Santa Clara, Calif.
Tracking guide wire 36A is sized for slidable movement within first
guide wire lumen 34A.
[0108] Stent delivery assembly 30 further includes second guide
wire lumen 39A which is associated with expandable member 35.
Second guide wire lumen 39A includes angle portion 39B and straight
portion 39C, and is firmly attached to outer surface 40 of catheter
31, at a point just proximal to expandable member 35. Integrated
stent-positioning guide wire 41A is sized for slidable movement
within second guide wire lumen 39A. A slit 39D is formed in lumen
39A near its distal end so that the stiff guide wire 41A can bow
outwardly as shown in FIG. 7B. The portion of guide wire 41A that
bows out of slit 39D will limit the advancement of catheter 31 as
will be further described infra. Integrated stent-positioning guide
wire 41A has distal end 41B, and proximal end 41C which extends out
of the patient. Again, it is preferred that integrated
stent-positioning guide wire 41A be a fairly stiff wire as
previously described, for the reasons set forth below in delivering
and implanting the stents in the bifurcation.
[0109] In an alternative embodiment, catheter 31 can have an angled
expandable member 42 as depicted in FIG. 8. The proximal end of the
expandable member is angled to coincide with the angle of proximal
angled stent 10 (not shown in FIG. 8 for clarity). This embodiment
is particularly useful in delivering the angled stent since the
second guide wire lumen 39A, and its angled portion 39B, have the
same angle as the stent and the proximal end of the expandable
member.
[0110] In further keeping with the invention, as depicted in FIGS.
9A-11D, proximal angled stent 10 is mounted on side-branch catheter
31 and implanted in side-branch vessel 5. The method of achieving
proximal angled stent implantation is as follows.
[0111] In keeping with the preferred method of the invention,
proximal angled stent 10 first is tightly crimped onto expandable
member 35 for low-profile delivery through the vascular system.
[0112] In the preferred embodiment of the side-branch catheter
system 30 (side-branch catheter plus proximal angled stent), distal
end 36B of guide wire 36A is advanced into side-branch vessel 5 and
distal to the target area, with proximal end 36C remaining outside
the patient. The side-branch catheter 31 is then advanced within a
guiding catheter (not shown) along tracking guide wire 36A until
distal end 32 of the catheter is just proximal (about 1 cm) from
entering side-branch vessel 5. Up to this point, guide wire 41A
resides in second guide wire lumen 39A so that distal end 41B of
the wire preferably is near, but not in, angled portion 39B of
guide wire lumen 39A. This method of delivery prevents the two
guide wires from wrapping around each other, guide wire 41A being
protected by the catheter during delivery. The distal end 41B of
integrated stent positioning guide wire 41A is then advanced by
having the physician push proximal end 41C from outside the body.
The distal end 41B of the integrated stent-positioning guide wire
travels through guide wire lumen 39A and angled portion 39B and
passes close to proximal end 14 of angled stent 10 and expandable
member 35 and exits lumen 39B. As guide wire 41A is advanced into,
through and out of lumen 39B, the stiffness of the wire causes it
to bow outwardly through slit 39D in the distal portion of lumen
39A. Thus, as can be seen for example in FIGS. 9B, 10A, 10B, and
11B-11D, the positioning guide wire bows outwardly and due to its
stiffness, provides a bumper against the ostium of the side-branch
vessel to assist in positioning and deploying the stents. The
stent-positioning guide wire 41A is advanced in the main vessel
until distal end 41B is distal to side-branch vessel 5. The
catheter is then advanced into side-branch vessel 5 until
resistance is felt from the stent-positioning guide wire 41A
pushing up against the ostium of side-branch vessel 5. As
previously described, stent-positioning wire 41A is relatively
stiff, as is tracking guide wire 36A, so that they can properly
orient side-branch catheter 31 as it is advanced into side-branch
vessel 5. Angled portion 39B of second guide wire lumen 39A is
angled to assist in rotating the side-branch catheter into proper
position into the side-branch vessel. If the stent approaches
side-branch vessel 5 in the incorrect position, as depicted in
FIGS. 11A-11D, stent-positioning wire 41A would be forced to make a
very acute angle. The wire stiffness, however, prevents this from
happening and causes the wire to assume the position of least
stress. To relieve this stress buildup, wire 41A creates a torque
on angled portion 39B causing guide wire lumen 39A and side-branch
catheter 31, with proximal angled stent 10, to rotate into the
correct position. Preferably, slit 39D is formed on catheter 31
outer surface near angled portion 39B so that stent-positioning
guide wire 41A can bow outwardly out of slit 39D thereby increasing
the ability to torque the catheter and the proximal angled
stent.
[0113] Thereafter, proximal angled stent 10 mounted on the
expandable member 35 is aligned across the target area, and viewed
under fluoroscopy, the acute angle 18 on the proximal end of the
proximal angled stent is aligned at the intersection of side-branch
vessel 5 and main-vessel 6 (the ostium of the side-branch vessel)
so that the proximal angled stent completely covers the target area
in side-branch vessel 5, yet does not extend into the main-vessel
6, thereby compromising blood flow. The expandable member 35, which
is typically a non-distensible balloon, is expanded by known
methods, thereby expanding the proximal angled stent into contact
with side-branch vessel 5, and thereby implanting the proximal
angled stent in the side-branch vessel. Thereafter, expandable
member 35 is deflated and side-branch catheter assembly 31 is
withdrawn from the patient's vasculature. The side-branch catheter
31 is designed so that both tracking guide wire 36A and
stent-positioning guide wire 41A can be left in their respective
vessels should sequential or simultaneous high pressure balloon
inflation be required in each of the vessels in order to complete
the stenting procedure. In other words, the integrated positioning
wire can be unzipped through the slit (not shown) from the proximal
100 cm of the catheter thereby allowing it to act as a rapid
exchange wire. Preferably, high pressure balloons are inflated
simultaneously in the main vessel and proximal angled stents in
order to avoid deforming one stent by unopposed balloon inflation
within the other one. This additional step is a matter of physician
choice. Utilizing this preferred method, side-branch vessel 5 can
be stented without the need for stenting the main vessel, as shown
in FIGS. 11A-11D.
[0114] If necessary, main-vessel 6 also can be stented after
stenting the side-branch vessel. In that regard, and in keeping
with the invention, main-vessel catheter assembly 50 is provided
for implanting main-vessel stent 20, as depicted in FIGS. 12A to
13E. In one preferred embodiment, as shown in FIGS. 12A-12C,
main-vessel catheter 50 includes distal end 51 which is configured
for advancement within the patient's vasculature, and proximal end
52 which remains outside the patient. The main-vessel catheter
includes guide wire lumen 53A having distal end 53B and side port
53C, which is proximal to the balloon portion of the catheter. Side
port 53C is provided in a so-called rapid-exchange catheter system
which includes a slit (not shown) as is known in the art.
Expandable member 54 is located near distal end 51 of main-vessel
catheter 50. Typically, expandable member 54 is a non-distensible
balloon of the type known in the art for delivering and expanding
stents.
[0115] In further keeping with the invention, positioning guide
wire lumen 55A is positioned partly on the catheter shaft and
partly on expandable member 54, and is configured for slidably
receiving integrated stent-positioning guide wire 56A. Prior to
stent delivery, guide wire 56A resides in guide wire lumen 55A and
only during stent delivery is it then advanced into and through
angled portion 55B of the lumen.
[0116] Other preferred embodiments for implanting main-vessel stent
20 in main-vessel 6 are depicted, for example, in FIGS. 12D-12F.
This embodiment is identical to that depicted in FIGS. 12A-12C,
with the addition of ramp 57 which is mounted on balloon 35 and
provides a slight incline for guide wire 56A as it exits guide wire
lumen 55A. As the guide wire slides along ramp 57, distal portion
56B of the guide wire will move radially outwardly which helps
position the guide wire and orient it into the side-branch vessel.
In another preferred embodiment for implanting the main-vessel
stent in the main vessel, as depicted in FIGS. 12G-12I, guide wire
lumen 55A passes underneath main-vessel stent 20 and on top of
balloon 35. The distal end 55B curves along the balloon so that as
guide wire 56B advances out of the distal end 55B of the lumen, it
is travelling radially outwardly so that it can more easily locate
and advance into the side-branch vessel 5.
[0117] In still another preferred embodiment for implanting
main-vessel stent 20 in the main-vessel 6, as depicted in FIGS.
12J-12L, guide wire lumen 55A is positioned under stent 20 and
terminates at distal end 55B in the middle of aperture 25. The
distal end 55A of the guide wire lumen will spring outwardly which
facilitates advancing guide wire distal end 41B into the side
branch vessel. A distal guide wire lumen 58 is attached to the
balloon 35 outer surface and extends from aperture 25 to
essentially the distal end of the catheter.
[0118] In one preferred method of implanting main-vessel stent 20
in main-vessel 6, as depicted in FIGS. 12A-12I and 13A-13D, guide
wire 41A remains in position in main-vessel 6, while the
side-branch guide wire 36A is withdrawn from the patient.
Main-vessel catheter 50 is backloaded onto guide wire 41A by
inserting proximal end 41B of the wire into the distal end of the
catheter and into guide wire lumen 53A. Main-vessel catheter 50 is
advanced over guide wire 41A and viewed under fluoroscopy until
main-vessel stent 20 is positioned in main-vessel 6, just proximal
to side-branch vessel 5. The distal end 56B of the integrated
stent-positioning guide wire 56A is then advanced by the physician
pushing on proximal end 56C from outside the body. The distal end
56B of wire 56A advances into and through positioning guide wire
lumen 55A and passes underneath the proximal end of the main-vessel
stent 20 and exits the angled portion 55B of the lumen and enters
side-branch vessel 5. The main-vessel catheter 50 is then advanced
distally into the main vessel until resistance is felt from the
stent-positioning guide wire 56A pushing up against the ostium of
the side-branch vessel. The stiffness of stent-positioning guide
wire 56A causes the main-vessel catheter 50, with main-vessel stent
20 thereon, to rotate so that aperture 25 is facing the side-branch
vessel 5 ostium and proximal angled stent 10 already implanted.
[0119] Expandable member 54, which is typically a non-distensible
expandable balloon, is inflated thereby expanding main-vessel stent
20 into contact with main-vessel 6. Aperture 25 correspondingly
expands and when properly aligned, provides a blood flow path
between aperture 25 and proximal angled stent 10 implanted in
side-branch vessel 5. As can be seen in FIGS. 12A-12I and 13A-13D,
positioning guide wire lumen 55A is positioned on expandable member
54, such that when the expandable member is inflated, positioning
guide wire lumen 55A does not interfere with implanting main-vessel
stent 20. After the main-vessel stent is implanted in the main
vessel, expandable member 54 is deflated, and main-vessel catheter
50 withdrawn from the patient. As seen in FIG. 14, the bifurcated
vessel has been fully covered by the stents, side-branch vessel 5
is covered by proximal angled stent 10, and main-vessel 6 is
covered by main-vessel stent 20, so that no portion of bifurcation
4 is left uncovered and there is no overlap in the implanted
stents.
[0120] In an alternative method of implanting main-vessel stent 20
in main-vessel 6 as depicted in FIGS. 12J-12L, tracking guide wire
41A is advanced through guide wire lumen 55A and guide wire lumen
58 so that it advances distally of the distal end 51 of the
catheter. Thus, guide wire distal end 41B is advanced into the main
vessel so that it is distal of the side-branch vessel. Guide wire
56A, which until this point has remained within guide wire lumen
53A (see FIG. 12K), is advanced distally as depicted in FIG. 12L
and advanced into the main vessel distally of the side-branch
vessel. Guide wire 41A is then withdrawn proximally through guide
wire lumen 58 until guide wire distal end 41B is able to exit guide
wire lumen distal end 55B, as shown in FIG. 12L. Since guide wire
lumen 55B is preformed and has bias, it will spring outwardly.
Guide wire 41A can then be advanced into the side-branch vessel for
further positioning. As the catheter 50 is advanced over the guide
wires, distal portion 41B of the guide wire will push against the
ostium of the side-branch vessel thereby insuring the location of
main-vessel stent 20, and importantly aperture 25 will align with
the opening to the side-branch vessel 5.
[0121] A non-angulated stent (see FIG. 15) can be implanted using
the catheter system of FIGS. 7A-11D for stenting a side-branch
vessel having an origin approaching 90.degree. in its takeoff from
the main vessel. In this circumstance the positioning wire serves
solely to arrest the forward movement of the stent precisely at the
origin of the vessel for more precise positioning. However, acute
angle 18 is appropriate for a bifurcated vessel 4 in which the
angulation is acute angle 18, or less than 90.degree.. Thus,
consideration could be given to standard 30.degree., 45.degree.,
and 60.degree. angled stent designs for proximal angled stent 10,
which should provide sufficient luminal wall coverage when keeping
with the present invention. Proximal angled stent 10 has a wide
range of applicability and can be used for stenting ostial
side-branch lesions, ostial circumflex or left anterior descending
(LAD) lesions where the bifurcation is an acute angle, or less than
90.degree., and ostial lesions involving the angulated origin of a
right coronary or vein graft. Importantly, the stents of the
present invention provide full coverage of the ostial intima
without protruding into the main vessel or without compromising
subsequent access to the distal portion of the main vessel.
[0122] In order to assist in properly aligning both proximal angled
stent 10 and main-vessel stent 20 in side-branch vessel 5 and
main-vessel 6, respectively, positioning guide wire lumen 39A, on
side-branch catheter 31, and guide wire lumen 55A, on main-vessel
catheter 50, can be radiopaque, or have a radiopaque marker
associated therewith so that they are visible under fluoroscopy.
Thus, when advancing side-branch catheter 31 and main-vessel
catheter 50, the proper orientation can be more easily determined
by viewing the position of positioning guide wire lumen 39A in
connection with main-vessel 6 or positioning guide wire lumen 55A
in connection with aligning aperture 25 with side-branch vessel 5.
Additionally, positioning guide wire 56A for positioning
main-vessel stent 20 and positioning guide wire 41A for positioning
angled stent 10 are either radiopaque or have radiopaque portions,
such as gold markers, to assist in positioning and orienting the
catheters and stents during implantation and deployment.
[0123] While the foregoing description includes implanting proximal
angled stent 10 in side-branch vessel 5 prior to implanting
main-vessel stent 20 in main-vessel 6, in an alternative preferred
embodiment, the implanting procedure can be reversed. However, it
should be understood that by implanting main-vessel stent 20 in
main-vessel 6, and subsequently implanting proximal angled stent 10
in side-branch vessel 5, aperture 25 must be carefully aligned with
side-branch vessel 5 so that side-branch catheter 31 can be
advanced through expanded main-vessel stent 20 and aperture 25 and
into side-branch vessel 5 for implanting proximal angled stent
10.
[0124] While side-branch catheter 31 and main-vessel catheter 50
have been described herein as being of the rapid-exchange type,
they also can be of a conventional over-the-wire-type catheter. In
over-the-wire-type catheters, the guide wire lumen extends from the
distal end of the catheter to the proximal end with no side port as
is found in the rapid-exchange-type catheters. Typical of
over-the-wire-type catheters is the type disclosed in U.S. Pat.
Nos. 4,323,071 and B1 4,323,071, which are incorporated herein by
reference, and are commonly assigned and commonly owned by Advanced
Cardiovascular Systems, Inc., Santa Clara, Calif.
[0125] In one preferred embodiment of the invention, as depicted in
FIG. 15, main-vessel unmodified stent 60 can be configured without
the side aperture 25 of stent 20. Upon expansion, the individual
strut members 61 of unmodified stent 60 expand sufficiently to
permit a balloon catheter to be inserted therethrough, and
expanded, to form an aperture which corresponds to the opening to
side-branch vessel 5.
[0126] In one preferred method of stenting the bifurcation,
side-branch vessel 5 is first stented as described, for example, in
the manner shown in FIGS. 9A through 11D. Thereafter, main-vessel 6
is stented with unmodified main-vessel stent 60, which does not
have an aperture formed in the side of the stent. As shown in FIGS.
15-18, unmodified stent 60 is mounted on expandable portion 54 of
main-vessel catheter 50. Main-vessel catheter 50 is backloaded onto
the proximal end of guide wire 41A which is already in position in
the main vessel. Main-vessel catheter 50 is advanced over the guide
wire and viewed under fluoroscopy until stent 60 is positioned in
the main vessel about one cm proximal to the side-branch vessel.
The distal end 56B of integrated stent-positioning guide wire 56A
is then advanced by the physician by pushing the proximal end 56C
from outside the body. The distal end 56B of wire 56A travels
through guide wire lumen 55A and passes underneath the proximal end
of unmodified stent 60 and exits the angled end of the lumen 55B
and enters side-branch vessel 5. The main-vessel catheter 50 is
then advanced distally into the main vessel until resistance is
felt from the stent-positioning guide wire 56A pushing up against
the ostium of side-branch vessel 5. The stiffness of
stent-positioning guide wire 56A causes the main-vessel catheter 50
with unmodified stent 60 to rotate so a stent cell 62 is precisely
facing the side-branch vessel 5 ostium. Expandable member 54 is
expanded by known means so that unmodified stent 60 expands into
contact with main-vessel 6. Expandable member 54 is then deflated,
catheter 50 is withdrawn from the patient's vascular system,
leaving guide wire 56A in the side branch.
[0127] At this point, proximal angled stent 10 is implanted in the
side-branch vessel and unmodified main-vessel stent 60 is implanted
and extends across side-branch vessel 5. In order to provide an
opening in unmodified main-vessel stent 60 that aligns with the
opening to the side-branch vessel, third catheter 65, which can be
a standard PTCA catheter, is backloaded onto guide wire 56A,
already in side-branch vessel 5, and advanced within the patient's
vascular system over the guide wire. As shown in FIG. 18, distal
end 66 of catheter 65 is advanced over guide wire 56A until the
distal end 66 of catheter 65 begins to pass through cell 62 of
unmodified main-vessel stent 60 and enter side-branch vessel 5.
Catheter 65 can be of a known type used in angioplasty, as
described above, having a non-distensible member or balloon 67.
Once balloon 67 is positioned through stent cell 62 and in the
opening of side-branch vessel 5, it is expanded, thereby expanding
some of struts 61 comprising unmodified stent 60 and forming a
substantially circular opening from main-vessel 6 through
unmodified stent 60 and into side-branch vessel 5. In essence,
balloon 67 spreads apart some of the struts of unmodified stent 60
to form an opening in stent 60 that corresponds to the opening to
side-branch vessel 5, thereby providing a clear blood flow path
between the main vessel and the side-branch vessel.
[0128] Unmodified main-vessel stent 60 is positioned such that it
crosses the opening to side-branch vessel 5. As set forth above, a
particularly well suited stent for this embodiment includes a stent
distributed under the tradename MultiLink.RTM. Stent, manufactured
by Advanced Cardiovascular Systems, Inc., Santa Clara, Calif. By
implanting unmodified main-vessel stent 60 in main-vessel 6 with an
appropriate stent cell precisely aligned with the side-branch
ostia, dilatation through this same cell over wire 56A assures a
fully expanded and non-distorted cell at the ostium of side-vessel
5.
[0129] In an alternative embodiment, as shown in FIGS. 19A-19C,
unmodified stent 60 is implanted first, then the side-branch
proximal angled stent 10 is implanted. In the preferred method of
deploying unmodified stent 60, the unmodified stent 60 can be
mounted on expandable portion 54 of main-vessel catheter 50.
Main-vessel catheter 50 is backloaded onto the proximal end of
guide wire 41A. Main-vessel catheter 50 is advanced over guide wire
41A and viewed under fluoroscopy until unmodified stent 60 is
positioned in main-vessel 6, proximal to side-branch vessel 5. The
distal end of the integrated stent-positioning guide wire 56B is
then advanced by the physician pushing the proximal end 56C from
outside the body. The distal end 56B of wire 56A travels through
second guide wire lumen 55A and passes underneath the proximal end
of unmodified stent 60 and exits the angled end of the lumen 55B
and enters side-branch vessel 5. The main-vessel catheter 50 is
then advanced distally into the main vessel until resistance is
felt from the stent-positioning guide wire 56A pushing up against
the ostium of the side-branch vessel 5. The stiffness of
stent-positioning guide wire 56A causes the main-vessel catheter 50
with unmodified stent 60 to rotate so a stent cell 62 is precisely
facing the side-branch vessel 5 ostium. Expandable member 54 is
expanded by known means so that unmodified stent 60 expands into
contact with main-vessel 6. Expandable member 54 is then deflated,
and catheter 50 is withdrawn from the patient's vascular system,
leaving guide wire 56A in side branch 5.
[0130] In further keeping with the preferred method of stenting, as
shown in FIG. 19B, third catheter 65, which can be a standard PTCA
catheter, is backloaded onto guide wire 56A already in side-branch
vessel 5 and advanced within the patient's vascular system over the
guide wire. Distal end 66 of catheter 65 is advanced over guide
wire 56A until the distal end 66 of the catheter begins to pass
through struts 61 of stent cell 62 of unmodified main-vessel stent
60 and enter side-branch vessel 5. Catheter 65 can be of a known
type used in angioplasty, as described above, having a
non-distensible member or balloon 67. Once balloon 67 is positioned
through a stent cell 62 the opening of side-branch vessel 5, it is
expanded, thereby expanding some of the struts comprising
unmodified stent 60 and forming a substantially circular opening
from main-vessel 6 through unmodified stent 60 and into side-branch
vessel 5. In essence, balloon 67 spreads apart the struts 61 of
unmodified stent 60 to form an opening in the unmodified stent that
corresponds to the opening to side-branch vessel 5, thereby
providing a clear opening for further stenting side-branch vessel
5.
[0131] With the main vessel now stented as depicted in FIGS.
19A-19C, side-branch vessel 5 is stented in the same manner as
described in FIGS. 9-11. The only difference is that in FIG. 19,
unmodified main-vessel stent 60 already is implanted when catheter
31 is advanced into side-branch vessel 5. Side-branch catheter 31
is backloaded onto guide wire 36A already in side-branch vessel 5.
Side-branch catheter 31 is then advanced until the distal tip of
side-branch catheter 31 just enters the side-branch vessel 5
ostium. The distal end 41B of the integrated guide wire 41A is then
advanced by the physician pushing the proximal end 41C from outside
the body. The distal end 41B of the integrated stent-positioning
guide wire travels through second guide wire lumen 39A and angled
portion 39B and passes close to the proximal end of proximal angled
stent 10 and expandable member 35 and exits lumen 39B. The
stent-positioning guide wire 41A is advanced until the distal end
41B is distal to side-branch vessel 5. The catheter is then
advanced into the side-branch vessel until resistance is felt from
the stent-positioning guide wire 41A pushing up against the ostium
of the side-branch vessel. As previously described,
stent-positioning wire 41A is relatively stiff, as is tracking
guide wire 36A, so that they can properly orient side-branch
catheter 31 as it is advanced into the side-branch vessel. Angled
portion 39B of second guide wire lumen 39A is angled to assist in
rotating the side-branch catheter into proper position into
side-branch vessel 5. If the stent approaches the side-branch
vessel in the incorrect position, the stent-positioning wire 41A
would be forced to make a very acute angle. The wire stiffness,
however, prevents this from happening and causes the wire to assume
the position of least stress. To relieve this stress buildup, wire
41A creates a torque on angled portion 39B causing guide wire lumen
39A and side-branch catheter 31 with proximal angled stent 10 to
rotate into the correct position. Once the proximal angled stent is
positioned in side-branch vessel 5, expandable member 35 is
expanded so that the proximal angled stent expands into contact
with side-branch vessel 5, making sure that proximal end 14 of
proximal angled stent 10 covers and is aligned with the side-branch
vessel 5 at bifurcation 4. Proximal end 14 is aligned so that it
coincides with acute angle 18, thereby ensuring that all portions
of side-branch vessel 5 are covered by the proximal angled stent,
where side-branch vessel 5 meets main-vessel 6. An unobstructed
blood-flow path now exists between expanded unmodified stent 60 and
main-vessel 6 through the opening previously formed and into
side-branch vessel 5 and through implanted proximal angled stent
10.
[0132] Prior art devices that have attempted to first stent the
main vessel and randomly select a stent cell to expand for
alignment with the side-branch vessel, have generally failed. One
such approach, known as the "monoclonal antibody" approach, as
depicted in FIGS. 19D and 19E, depict what can happen when an
inappropriate target stent cell is selected randomly and then
expanded by a high pressure balloon. As shown in FIG. 19D, which is
a view looking down side-branch vessel 5 in cross-section at a
prior art stent 68, the physician randomly selects stent cell 69
which is a sub-optimal cell to expand with the balloon portion of a
catheter. As depicted in FIG. 19E, after balloon expansion in the
suboptimal cell 69, entry into the cell with a catheter may be
impossible or, if accomplished, expansion of the balloon may be
incomplete. The aperture created will be inadequate and major
distortion in the adjacent stent struts may occur. Consequences may
include subacute thrombosis or restenosis. With the present
invention, as shown in FIGS. 19A-19C, the target stent cell 62 is
the optimal cell for expansion, and is preselected with a wire in
place before stent deployment (that same wire remaining in place
for subsequent access), and is oriented optimally with respect to
the side-branch ostium prior to deployment. The resulting expansion
as shown in FIG. 19F, guarantees an optimal aperture where the
stent struts have been expanded providing a blood flow path from
the main vessel to the side-branch vessel.
[0133] In another alternative embodiment for stenting a
bifurcation, as depicted in FIGS. 20A-20C, main-vessel catheter 70
includes expandable member 71 near its distal end, while the
proximal end of the catheter (not shown) is similar to those
previously described and can be either of the rapid-exchange or
over-the-wire types. Catheter 70 includes tracking guide wire lumen
72 for slidably receiving tracking guide wire 73, lumen 72
extending at least partially through the catheter in the
rapid-exchange configuration and all the way through the catheter
in the over-the-wire configuration. The catheter also includes a
positioning guide wire lumen 74 that is associated with the
catheter outer surface and extends onto and is attached to at least
a portion of expandable member 71. As shown in FIG. 20A,
positioning guide wire lumen 74 extends along the expandable member
and ends just at the distal taper of the expandable member. As
depicted in FIGS. 20B and 20C, positioning guide wire lumen 74 can
be formed of two sections, namely distal section 75 attached to the
distal tip of the catheter, and proximal section 76 extending along
and attached to the expandable member and the catheter. As
previously described, guide wires 73, 77 are intended to be
relatively stiff wires so that they can more easily maneuver the
catheter. In these embodiments, stent 78 is mounted on the
expandable member and over positioning guide wire lumen 74.
Positioning guide wire 77 is configured for slidable movement
within positioning lumen 74.
[0134] In the preferred method of stenting a vessel just proximal
to a bifurcation using main-vessel catheter 70, tracking guide wire
73 is first positioned within the main vessel as previously
described. The catheter is then backloaded onto the guide wire by
inserting the wire into the tracking guide wire lumen 72 and
advancing the catheter into the patient's vascular system. At this
point, positioning guide wire 77 resides within positioning guide
wire lumen 74 and is carried into the main vessel where it will be
released and advanced. Once the catheter has reached the target
area, positioning guide wire 77 is advanced distally out of the
positioning guide wire lumen (for FIG. 20A) or pulled back slightly
out of distal section 75 of the positioning guide wire lumen (for
FIGS. 20B and 20C). Once released by removal of the guide wire,
distal section 75 will spring out so that the positioning guide
wire can seek out and be advanced into the side-branch vessel. Once
the positioning guide wire is advanced in the side-branch vessel,
the catheter is again advanced and the stent is implanted in the
main vessel in a manner similar to that described for other
embodiments. The catheter of FIGS. 20A-20C is designed to allow
deployment of a stent very near but not "snowplowing" a bifurcation
or side branch and is configured for treating bifurcations as
depicted in FIGS. 23A-25B. A commonly encountered situation in
which catheter 70 would be used is an LAD that has disease right at
and proximal to the diagonal take-off. After a careful look at
multiple views, the physician should be convinced that the diagonal
is spared, but the lesion is very close and or immediately adjacent
to the diagonal take-off, as shown in FIG. 20D. It is very
difficult to position a standard stent in the LAD and be certain
that the lesion is fully covered and the diagonal is not snowplowed
or jailed. The catheter 70, having one wire in the LAD (main
vessel) and the other in the diagonal (side-branch vessel), would
allow precise definition of the bifurcation and avoid these
problems. Square stent 78A, which has both ends transverse to the
stent axis, could be deployed just proximal to the carina, in which
case the stent distal end may need to be flared a bit, or more
likely, relaxed back to where the positioning guide wire 77 is
resting against the proximal aspect of the ostium, visually
defining the ostium in relationship to the stent and allowing
precise deployment.
[0135] Several alternative embodiments of main-vessel catheter 70
shown in FIG. 20A, are depicted in FIGS. 20E, 21 and 22. The
catheter device shown in FIG. 20E is similar to that shown in FIG.
20A, with the exception that ramp 57 is employed just distal of the
distal end of the guide wire lumen 74 so that as guide wire 77
exits the lumen, it will move outwardly along ramp 57 so that it
more easily advances into the side-branch vessel. Likewise, as
shown in FIGS. 21 and 22, which are similar to the catheter
described and depicted in FIGS. 20B and 20C, it is intended that
guide wire 77 move outwardly so that it can more easily be advanced
into the side-branch vessel. In that regard, the distal end of
guide wire lumen 74 is biased outwardly as shown in FIG. 22, so
that as the guide wire 77 is pulled back from lumen 75, the distal
end of guide wire lumen 74 will spring outwardly thereby assisting
guide wire 77 in moving radially outwardly to be positioned in the
side-branch vessel.
[0136] In order to implant a square main-vessel stent 78A in a main
vessel, where the disease is at or just proximal to the side-branch
vessel, catheter 70 as depicted in FIGS. 21 and 22 is well suited.
For example, catheter 70 is advanced over wire 77 until the
catheter is positioned just proximal of the side-branch vessel.
Guide wire 73, which up to this point has been contained within
catheter 70, is advanced into the main vessel so that it is distal
of the side-branch vessel. Guide wire 77 is then withdrawn
proximally so that its distal end 77A is withdrawn from lumen 75,
whereupon wire 77 and the distal end of guide wire lumen 74 spring
outwardly thereby assisting the positioning of guide wire 77 into
the side-branch vessel. The wire is then advanced into the
side-branch vessel and catheter 77 is advanced so that wire 77
rests on the proximal ostium of the side-branch vessel, wherein
square stent 78A can then be expanded to cover the diseased
portion, but not span or cover (jail) the opening to the
side-branch vessel.
[0137] If the diseased portion of a main vessel is directly
adjacent the opening to the side-branch vessel, as depicted in FIG.
20F then the catheter system as depicted in FIG. 20A can be
incorporated only it would implant distal angled stent 78B. As
shown in FIG. 20F, stent 78B has an angle at its distal end which
coincides with the opening to the side-branch vessel so that the
diseased portion of the main vessel is covered by the distal end of
the stent, with the angle of the stent angled proximally so that
the side-branch vessel is not covered or jailed. Various
alternatives of square stent 78A and distal angled stent 78B are
used for treating various conditions as depicted in FIGS. 23A
through 26B.
[0138] In another alternative embodiment as depicted in FIGS.
27-33, a dual balloon Y-shaped catheter assembly is provided to
stent a bifurcation. In this embodiment, a Y-shaped stent is
implanted to cover the bifurcation. Catheter 90 includes first and
second expandable members 91,92 that are configured to reside side
by side (Y-shaped) for low profile delivery and to spring apart for
implanting the stents. Locking ring 93 may be used to assist in
holding the expandable members together until just prior to use, at
which time it is removed. A guide wire lumen 95 extends at least
through a portion of the catheter and slidably receives guide wire
96. Guide wire lumen 98 extends at least through a portion of the
catheter and slidably receives guide wire 99. Guide wire lumen 98
includes distal section 98A and 98B. A Y-shaped stent 100 is
mounted on the first and second expandable members 91, 92.
[0139] In the preferred method of stenting the bifurcated vessels,
as shown in FIGS. 29 to 33, guide wire 99, previously positioned
distal to the bifurcation in one limb (perhaps the most vulnerable
to problems for wire recrossing), is back loaded into lumens 98A
and 98B and catheter 90 is advanced over wire 99 so that the
catheter is advanced distally beyond the bifurcation. Guide wire 96
which has been contained in lumen 95 to this point, is advanced
along guide wire 99. Wire 99 is then withdrawn until its distal end
pulls out of the distal section 98A. As guide wire 99 is pulled
back (proximally), the first and second expandable members 91,92,
which are normally biased apart, are released and now spring apart.
The wire whose lumen is most distant (lateral) to the bifurcation
(in this case wire 96) is then advanced into the distal vessel and
the other wire (in this case 99) withdrawn as seen in FIG. 29B. The
catheter is then withdrawn proximally so that the expandable
members 91, 91A are now proximal to the bifurcation as depicted in
FIG. 29C and the other guide wire (in this case wire 99) advanced
into the other limb of the bifurcation as shown in FIG. 30.
Catheter 90 is then advanced distally over both guide wires 96 and
99, as shown in FIG. 31, until stent 100 is positioned in the
bifurcation of the intersection of the vessels 105,106. Due to the
appropriate wire selection, rotation of no more than 90.degree.
will be required. Stent 100 is implanted by inflating expandable
members 91,92 in a known manner. The expandable members are then
deflated, and the catheter is withdrawn from the patient. The novel
arrangement of guide wires 96 and 99 and their respective lumens
permit single unit transport of a Y stent to the distal target site
without wire wrapping problems and it allows for minimal
requirements of rotation of the device (less than 90.degree.) for
optimal deployment (allowing minimal twist deformity). The guide
wires may be left in place for further intervention such as
finishing the stents with simultaneous high pressure balloon
inflation.
[0140] In an alternative embodiment of the invention, a pair of
stents having varying stent cell density are implanted in a
bifurcated vessel, as depicted in FIGS. 34-36C.
[0141] As shown in FIG. 34, apertured stent 115 is provided in
which aperture 116 is positioned on its outer surface. Stent 115
includes heavy stent cell density 117 and light stent cell density
118 along its outer surface. As can be seen in FIG. 35, two stents
115 have been combined so that the light density of one overlaps
the light density of the other causing the combined stents to
create relatively uniform heavy cell density and thus providing
relatively uniform heavy cell density over the entire bifurcated
vessel wall.
[0142] As shown in FIGS. 36A to 36C, two stents 115 are implanted
to stent the bifurcation. For sake of clarity, as shown in FIG.
36A, apertured stent 115 shown implanted in the main vessel such
that aperture 116 spans and provides an opening to the side-branch
vessel while heavy stent cell density 117 provides full coverage of
the distal main vessel by stent 115. As depicted in FIG. 36B,
apertured stent 115 is partially implanted in the side-branch
vessel and partially implanted in the main vessel, in this case
with aperture 116 facing the continuing lumen of the main vessel.
More specifically, heavy stent cell density portion 117 is
implanted in the side-branch vessel, while light stent cell density
118 is implanted in the main vessel, with aperture 116 providing an
opening for blood flow through the main vessel. It is intended that
stent 115 be implanted first as seen in FIG. 36A and that a second
stent 115 subsequently be implanted as shown in 36B or, by
physician preference, this sequence may be reversed. Thus, in FIG.
36C, both stents 115 have been implanted, and both apertures 116
provide openings so that blood flow is unimpaired through both main
vessel and side-branch vessel and no stent struts are left
unapposed. The light stent cell density portions 118 of both 115
stents overlap proximal to the bifurcation, thereby insuring that
there is full coverage of the bifurcated area by heavy stent cell
density. Both stents 115 are implanted with the catheter delivery
system described herein which includes a positioning wire to
accurately position and implant the stents in the bifurcated
vessels.
[0143] While the invention herein has been illustrated and
described in terms of an apparatus and method for stenting
bifurcated vessels, it will be apparent to those skilled in the art
that the stents and delivery systems herein can be used in the
coronary arteries, veins and other arteries throughout the
patient's vascular system. Certain dimensions and materials of
manufacture have been described herein, and can be modified without
departing from the spirit and scope of the invention.
* * * * *