U.S. patent application number 11/148712 was filed with the patent office on 2006-12-14 for apparatus and methods for deployment of multiple custom-length prostheses (ii).
This patent application is currently assigned to XTENT, INC., A Delaware Corporation. Invention is credited to Stephen Kao.
Application Number | 20060282149 11/148712 |
Document ID | / |
Family ID | 38006345 |
Filed Date | 2006-12-14 |
United States Patent
Application |
20060282149 |
Kind Code |
A1 |
Kao; Stephen |
December 14, 2006 |
Apparatus and methods for deployment of multiple custom-length
prostheses (II)
Abstract
Apparatus for delivering stents to body lumens include one or
more tubular prostheses carried at the distal end of a catheter
shaft, a sheath slidably disposed over the prostheses, and a
guidewire tube extending from within the sheath to the exterior of
the sheath through an exit port in a sidewall thereof A guidewire
extends slidably through the guidewire tube. The sheath can be
moved relative to the catheter shaft and the guidewire tube to
expose the prostheses for deployment. Methods of delivering stents
are also provided.
Inventors: |
Kao; Stephen; (Sunnyvale,
CA) |
Correspondence
Address: |
LEVINE BAGADE HAN LLP
2483 EAST BAYSHORE ROAD, SUITE 100
PALO ALTO
CA
94303
US
|
Assignee: |
XTENT, INC., A Delaware
Corporation
Menlo Park
CA
|
Family ID: |
38006345 |
Appl. No.: |
11/148712 |
Filed: |
June 8, 2005 |
Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61F 2002/91508
20130101; A61F 2002/9155 20130101; A61F 2250/007 20130101; A61F
2002/91516 20130101; A61F 2/958 20130101; A61F 2/915 20130101; A61F
2002/9583 20130101; A61F 2002/9665 20130101; A61F 2250/0098
20130101; A61F 2002/91525 20130101; A61F 2250/0032 20130101; A61F
2/91 20130101; A61F 2/966 20130101; A61F 2220/005 20130101; A61F
2002/826 20130101; A61F 2002/91533 20130101; A61F 2220/0033
20130101; A61F 2250/0007 20130101; A61F 2002/91558 20130101 |
Class at
Publication: |
623/001.11 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. Apparatus for delivering a prosthesis into a target vessel of a
patient, comprising: a flexible catheter having proximal and distal
ends, said catheter comprising an outer sheath and an inner shaft;
and a plurality of tubular prostheses releasably carried near the
distal end of the catheter over the inner shaft and deployable
therefrom in selectable numbers, the outer sheath disposed over the
prostheses and being axially movable relative thereto; wherein at
least a portion of the tubular prostheses have a radiopaque marker
disposed thereon such that the number of prostheses deployed from
the catheter at one time may be visualized.
2. Apparatus as in claim 1 wherein the radiopaque marker is
disposed only on a portion of each prosthesis.
3. Apparatus as in claim 1 wherein the radiopaque marker comprises
a circumferential stripe on at least one end of each
prosthesis.
4. Apparatus as in claim 1 wherein each prosthesis has a plurality
of axial projections extending from at least one end thereof, the
axial projections being configured to interleave with axial
projections on an adjacent prosthesis, and the radiopaque marker is
disposed on the axial projections.
5. Apparatus as in claim 1 wherein the radiopaque marker comprises
a circumferential stripe in a middle region of each prosthesis.
6. Apparatus as in claim 1 wherein the radiopaque marker covers
only a portion of the prosthesis.
7. Apparatus as in claim 1 wherein the radiopaque marker comprises
a coating on the surface of the prostheses.
8. Apparatus as in claim 1 wherein the radiopaque marker comprises
a radiopaque component coupled to the prosthesis.
9. Apparatus as in claim 1 wherein the radiopaque marker is a
material selected from gold, silver, platinum, titanium, iridium,
and tungsten.
10. Apparatus as in claim 1 wherein the radiopaque marker is
configured so as to indicate the location of each prosthesis in a
line of prostheses deployed end-to-end in a vessel.
11. A method of determining the number of prostheses deployed in a
vessel comprising: deploying from a catheter a plurality of
prostheses end-to-end in a vessel; and visualizing radiopaque
markers on at least a portion of the prostheses, the radiopaque
markers indicating the location of each deployed prosthesis
relative to other of the deployed prostheses.
12. A method as in claim 11 wherein the prostheses have axial
projections on each end thereof, the axial projections on each
prosthesis interleaving with the axial projections on the adjacent
prosthesis.
13. A method as in claim 12 wherein the radiopaque marker is
disposed on the axial projections.
14. A method as in claim 11 further comprising retaining at least
one prosthesis in the catheter while the plurality of prostheses
are deployed in the vessel.
15. A method as in claim 11 further comprising selecting the number
of prostheses to deploy in the vessel from a total number of
prostheses carried by the catheter.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to vascular catheters, and
more specifically to stents and stent delivery catheters for
deployment in the coronary arteries and other vessels.
BACKGROUND OF THE INVENTION
[0002] Stenting has become an increasingly important treatment
option for patients with coronary artery disease. Stenting involves
the placement of a tubular prosthesis within a diseased coronary
artery to expand the arterial lumen and maintain the patency of the
artery. Early stent technology suffered from problems with
restenosis, the tendency of the coronary artery to become
re-occluded following stent placement. However, in recent years,
restenosis rates have decreased dramatically. As a result, the
number of stenting procedures being performed in the United States,
Europe, and elsewhere has soared.
[0003] Stents are delivered to the coronary arteries using long,
flexible vascular catheters typically inserted through a femoral
artery. For self-expanding stents, the stent is simply released
from the delivery catheter and it resiliently expands into
engagement with the vessel wall. For balloon expandable stents, a
balloon on the delivery catheter is expanded which expands and
deforms the stent to the desired diameter, whereupon the balloon is
deflated and removed.
[0004] Current stent delivery technology, however, suffers from a
number of drawbacks. For example, current stent delivery catheters
are not capable of customizing the length of the stent in situ to
match the size of the lesion to be treated. While lesion size may
be measured prior to stenting using angiography or fluoroscopy,
such measurements may be inexact. If a stent is introduced that is
found to be of inappropriate size, the delivery catheter and stent
must be removed from the patient and replaced with a different
device of correct size.
[0005] Moreover, current stent delivery devices cannot treat
multiple lesions with a single catheter. Current devices are
capable of delivering only a single stent with a single catheter,
and if multiple lesions are to be treated, a new catheter and stent
must be introduced for each lesion to be treated.
[0006] Further, current stent delivery devices are not well-adapted
for treating vascular lesions that are very long and/or in curved
regions of a vessel. Current stents have a discrete length that is
relatively short due to their stiffness. If current stents were
made longer so as to treat longer lesions, they would not conform
well to the curvature of vessels or to the movement of vessels on
the surface of the beating heart. On the other hand, any attempt to
place multiple stents end-to-end in longer lesions is hampered by
the inability to maintain appropriate inter-stent spacing and to
prevent overlap of adjacent stents.
[0007] Additionally, some stent delivery catheters and angioplasty
balloon catheters, particularly those having movable external
sheaths to enclose the stent or balloon, suffer from poor tracking
and cumbersome interaction with guidewires. Some such catheters
utilize an "over-the-wire" design in which the guidewire extends
through an inner lumen of the catheter from its proximal end to its
distal end, a design that makes catheter exchanges cumbersome and
time-consuming. Rapid exchange designs have also been proposed for
such catheters wherein the guidewire extends through the distal end
of the catheter and out through a port in a sidewall of the sheath.
However, in these designs the guidewire inhibits smooth retraction
of the sheath and, if the sheath is retracted a substantial
distance, the port can become so displaced from the distal end of
the catheter that the guidewire does not slide smoothly as the
catheter is moved.
[0008] Finally, many stent delivery catheters suffer from
inflexibility and high cross-sectional profile, which hamper
endovascular positioning.
[0009] For these and other reasons, stents and stent delivery
catheters are needed which enable the customization of stent length
in situ, and the treatment of multiple lesions of various sizes,
without requiring removal of the delivery catheter from the
patient. Such stents and stent delivery catheters should be capable
of treating lesions of particularly long length and lesions in
curved regions of a vessel, and should be highly flexible to
conform to vessel shape and movement. Such stent delivery catheters
should further be of minimal cross-sectional profile and should be
highly flexible for endovascular positioning through tortuous
vascular pathways.
BRIEF SUMMARY OF THE INVENTION
[0010] The invention provides apparatus and methods for delivering
prostheses or stents into body lumens. In one aspect of the
invention, an apparatus for delivering a prosthesis into a target
vessel comprises a flexible catheter shaft having proximal and
distal ends and a first lumen therein. A tubular prosthesis is
releasably carried near the distal end of the catheter shaft and is
expandable to a shape suitable for engaging the target vessel. A
sheath is disposed over the catheter shaft and the tubular
prosthesis and is axially movable relative thereto. The sheath has
proximal and distal ends, a sidewall, and an exit port in the
sidewall between the proximal and distal ends. A guidewire tube
extends through the exit port and has a distal extremity disposed
within the tubular prosthesis and a proximal extremity disposed
outside of the sheath, the guidewire tube being adapted for
slidably receiving a guidewire therethrough.
[0011] Preferably, the guidewire tube is slidable through the exit
port so that the sheath slides relative to the guidewire tube as it
is retracted to expose the prosthesis for deployment. Usually the
guidewire tube is fixed relative to the catheter shaft, and may be
attached thereto. If an expandable member is mounted to the
catheter shaft for prosthesis expansion, the guidewire tube may
extend through and attach to the expandable member.
[0012] Because the guidewire tube exits the sheath in a distal
extremity thereof the sheath has a low profile portion proximal to
the exit port that has a smaller diameter than the portion distal
to the exit port. Not only does this reduce the cross-sectional
profile, but increases the flexibility of the device.
[0013] The exit port may be cut into the sidewall of the sheath to
face laterally, or alternatively oriented so as to face generally
in a proximal direction. The exit port is usually positioned so as
to be closer to the distal end of the sheath than to the proximal
end thereof, and is preferably a distance of about 20-35 cm from
the distal end of the sheath. With the sheath advanced fully
distally over the catheter shaft, the proximal extremity of the
guidewire tube exposed outside the sheath is preferably about 3-15
cm in length, although various lengths are possible, even as long
or longer than the catheter shaft itself. The proximal end of the
guidewire tube is preferably disposed a distance of less than about
one-half the length of the catheter shaft from the distal end
thereof, but in some embodiments may extend further proximally,
even as far as the proximal end of the catheter shaft.
[0014] The apparatus of the invention may be configured to deliver
tubular prostheses that are either self-expanding or expandable by
a balloon or other expandable member. When self-expanding
prostheses are used, the sheath is adapted to constrain the
prosthesis in a collapsed configuration. Upon retraction of the
sheath, the prosthesis is released and self-expands to engage the
vessel.
[0015] For balloon-expandable prostheses, an expandable member is
mounted to the catheter shaft near the distal end thereof. The
tubular prosthesis is positionable over the expandable member for
expansion therewith. Usually the expandable member will comprise a
balloon in communication with an inflation lumen in the catheter
shaft for delivery of inflation fluid to the balloon. The sheath is
axially positionable relative to the expandable member and
configured to restrain expansion of a selected portion of the
expandable member. Preferably the sheath is reinforced to prevent
expansion thereof by the expandable member.
[0016] In a preferred aspect of the invention, the tubular
prosthesis comprises a plurality of prosthesis segments. The sheath
is axially movable relative to the prosthesis segments and
configured to restrain expansion of a selectable number of
prosthesis segments. In this way, lesions of various lengths may be
treated by adjusting the length of the prosthesis in situ, without
removal of the device from the body. In these embodiments, a pusher
may be slidably disposed within the sheath proximal to the tubular
prosthesis. The pusher has a distal end in engagement with the
tubular prosthesis for moving the tubular prosthesis relative to
the catheter shaft.
[0017] In a further aspect of the invention, a method of delivering
a prosthesis in a target vessel of a patient comprises inserting a
guidewire through the patient's vasculature to the target vessel;
slidably coupling a delivery catheter to the guidewire, the
delivery catheter having a sheath and a guidewire tube, a proximal
extremity of the guidewire tube being outside the sheath and a
distal extremity of the guidewire tube being inside the sheath, the
guidewire being slidably positioned through the guidewire tube;
advancing the delivery catheter over the guidewire to the target
vessel; retracting the sheath relative to the guidewire tube to
expose a tubular prosthesis carried by the delivery catheter; and
expanding the tubular prosthesis into engagement with the target
vessel.
[0018] Usually, the guidewire tube will extend through an exit port
in the sheath, and the guidewire tube will slide through the exit
port as the sheath is retracted. The method may include sealing the
exit port around the guidewire tube to restrict fluid flow
therethrough, but preferably the exit port allows some fluid flow
to provide flushing of the distal portion of the catheter.
[0019] In a preferred embodiment, an expandable member is fixed to
a distal portion of the guidewire tube and the tubular prosthesis
is positionable over the expandable member. The sheath is slidably
disposed over the prosthesis and the expandable member and may be
retracted a selectable distance to expose a desired length of the
prosthesis and expandable member. The tubular prosthesis will then
be expanded by expanding the expandable member. The sheath may be
used to cover a proximal portion of the expandable member to
constrain the proximal portion from expansion while a distal
portion of the expandable member expands. Usually, the expandable
member is inflatable and will be inflated by delivering inflation
fluid to the expandable member through an inflation lumen in the
catheter shaft. The guidewire tube preferably extends through the
interior of the expandable member, which may be attached to the
guidewire tube.
[0020] In a preferred aspect of the invention, the tubular
prosthesis comprises a plurality of prosthesis segments, and the
method includes positioning a first selected number of the
prosthesis segments on the expandable member for expansion
therewith. The method may further include positioning the sheath
over a second selected number of the prosthesis segments to
constrain expansion thereof. The first selected number of
prosthesis segments may be positioned on the expandable member by
pushing the first selected number with a pusher that is axially
slidable relative to the expandable member.
[0021] In alternative embodiments, the tubular prosthesis
self-expands when the sheath is retracted. In embodiments in which
the prosthesis comprises multiple prosthesis segments, the sheath
may be retracted relative to a selected number of such segments to
allow the segments to self-expand into contact with the vessel.
[0022] In another aspect, the invention provides a balloon catheter
for treating a target vessel that includes a flexible catheter
shaft having proximal and distal ends and a first lumen therein. An
expandable member is connected to the catheter shaft, and a sheath
is disposed over the catheter shaft and the expandable member and
is axially movable relative thereto. The sheath has an exit port in
a sidewall thereof between its proximal and distal ends. A
guidewire tube extends through the exit port and has a proximal
extremity disposed outside of the sheath and a distal extremity
disposed within the sheath that is coupled to the catheter shaft or
the expandable member or both. The guidewire tube is adapted for
slidably receiving a guidewire therethrough. The expandable member
preferably comprises a balloon in fluid communication with the
first lumen to receive inflation fluid therefrom. The sheath may be
positionable to constrain a first selected portion of the
expandable member from expansion while a second selected portion of
the expandable member expands.
[0023] In a preferred embodiment of the balloon catheter of the
invention, a tubular prosthesis is disposed on the expandable
member and is expandable therewith. The tubular prosthesis will
preferably comprise a plurality of unconnected stent segments that
are slidable relative to the expandable member. The sheath is
positionable to expose a first selected portion of the stent
segments while covering a second selected portion of the stent
segments.
[0024] In yet another aspect of the invention, an apparatus for
delivering a prosthesis into a target vessel comprises a flexible
catheter shaft having proximal and distal ends and a tubular
prosthesis slidably coupled to the catheter shaft, the tubular
prosthesis being expandable to a shape suitable for engaging the
target vessel. A pusher is provided for moving the tubular
prosthesis from a pre-deployment position to a deployment position
near the distal end of the catheter shaft. The apparatus further
includes a stop on the catheter shaft configured to engage the
tubular prosthesis when the tubular prosthesis is in the deployment
position.
[0025] In one embodiment, an expandable member is coupled to the
catheter shaft and the tubular prosthesis is adapted for expansion
by the expandable member. The expandable member, e.g. balloon, has
an interior, and the stop is preferably disposed within the
interior of the expandable member. The stop may also be disposed
outside of or on the exterior surface of the expandable member.
Alternatively, the tubular prosthesis is self-expanding and expands
upon being released from the catheter shaft.
[0026] In a preferred aspect, a plurality of tubular prostheses are
slidably coupled to the catheter shaft and are movable by the
pusher to the deployment position. In addition, a sheath may be
movably coupled to the catheter shaft and positionable over the
tubular prosthesis or prostheses.
[0027] In a further method of deploying a tubular prosthesis in a
target vessel according to the invention a catheter shaft is
positioned in a target vessel and the tubular prosthesis is moved
distally relative to the catheter shaft while the catheter shaft
remains in the target vessel until the prosthesis engages a stop
near the distal end of the catheter shaft. The tubular prosthesis
is then expanded to engage a wall of the target vessel.
[0028] After expanding the tubular prosthesis, a second prosthesis
(or any number of additional prostheses) may be moved distally
relative to the catheter shaft until the second prosthesis engages
the stop, and the second prosthesis then expanded to engage a wall
of the target vessel. Alternatively, a second prosthesis may be
moved distally relative to the catheter shaft simultaneously with
moving the tubular prosthesis, and both the second prosthesis and
the tubular prosthesis are expanded together to engage the wall of
the target vessel. Usually, the tubular prosthesis and any
additional prostheses are moved by a pusher movably coupled to the
catheter shaft.
[0029] The tubular prosthesis is preferably expanded by inflating a
balloon coupled to the catheter shaft. Alternatively, the tubular
prosthesis may be self-expandable.
[0030] Further, the method may include retaining a second
prosthesis in an unexpanded configuration on the catheter shaft
while the tubular prosthesis is expanded. In one embodiment, the
second prosthesis is retained within a sheath movably coupled to
the catheter shaft.
[0031] Further aspects of the nature and advantages of the
invention will become apparent from the detailed description below
taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a perspective view of a stent delivery catheter
according to the invention with sheath retracted and expandable
member inflated.
[0033] FIG. 2A is a side cross-section of a distal portion of the
stent delivery catheter of FIG. 1 with expandable member deflated
and sheath advanced distally.
[0034] FIG. 2B is a side cross-section of a distal portion of the
stent delivery catheter of FIG. 1 with expandable member inflated
and sheath retracted.
[0035] FIG. 2C is a side cross-section of a distal portion of a
stent delivery catheter illustrating radiopaque markers attached to
the guidewire tube.
[0036] FIG. 3 is a transverse cross-section through line 3-3 of
FIG. 2A.
[0037] FIG. 4 is a transverse cross-section through line 4-4 of
FIG. 2A.
[0038] FIG. 5A is a side view of a first embodiment of a stent
segment according to the invention in an unexpanded
configuration.
[0039] FIG. 5B is a side view of the stent segment of FIG. 5A in an
expanded configuration.
[0040] FIG. 6A is a side view of a second embodiment of a stent
segment according to the invention in an unexpanded
configuration.
[0041] FIG. 6B is a side view of two of the stent segments of FIG.
6A in an expanded configuration.
[0042] FIGS. 7A-7E are side cut-away views of the stent delivery
catheter of the invention positioned in a vessel with the stent
segments of FIGS. 5A-5B, illustrating various steps of delivering a
prosthesis according to the method of the invention.
[0043] FIG. 8 is a side cut-away view of the stent delivery
catheter of the invention positioned in a vessel with the stent
segments of FIGS. 6A-6B in a deployed configuration.
[0044] FIG. 9 is a perspective view of the distal portion of the
stent delivery catheter of the invention with a portion of the
outer sheath stripped away to reveal a garage member.
[0045] FIG. 9A is an end view of a stop member.
[0046] FIG. 10 is a planar view of a garage member.
[0047] FIG. 11 is a side view of a garage member attached to a pair
of mandrels.
[0048] FIG. 12A is a side view of an expandable member in its
expanded state.
[0049] FIG. 12B is a side view of an expandable member in its
contracted state and having a plurality of stent segments
thereon.
[0050] FIG. 12C is a side cross-section of an expandable member
according to the invention.
[0051] FIG. 13 is a side view of a pusher tube.
[0052] FIG. 13A is a cross-sectional view of the pusher tube of
FIG. 13 taken at line A-A.
[0053] FIGS. 14A-B are side views of a stent segment embodiment
having radiopaque markers affixed thereto.
[0054] FIGS. 15A-C are side views of stent segment embodiments
having radiopaque marker coatings applied thereto.
[0055] FIGS. 15D-E are side views of multiple stent segments in
their expanded configurations having radiopaque marker coatings
applied thereto.
[0056] FIG. 16 is a side view of a slider tube.
[0057] FIG. 16A is a cross-sectional view of the slider tube of
FIG. 16 taken at line A-A.
[0058] FIG. 17 is a side view of a slider body.
[0059] FIG. 17A is a cross-sectional view of the slider body of
FIG. 17 taken at line A-A.
[0060] FIG. 17B is an end view of the slider body of FIG. 17.
[0061] FIG. 18 is a side view of a slider cap.
[0062] FIG. 18A is an end view of the slider cap of FIG. 18.
[0063] FIG. 19 is a perspective view of a slider seal.
DETAILED DESCRIPTION OF THE INVENTION
[0064] The present application relates generally to copending U.S.
patent application Ser. No. 10/637,713, entitled "Apparatus and
Methods for Deployment of Vascular Prostheses," filed Aug. 8, 2003,
which application is hereby incorporated by reference.
[0065] A first embodiment of a stent delivery catheter according to
present invention is illustrated in FIG. 1. Stent delivery catheter
20 includes a catheter body 22 comprising an outer sheath 25
slidably disposed over an inner shaft 27 (not shown in FIG. 1). An
expandable member 24, preferably an inflatable balloon (shown in an
inflated configuration), is mounted to inner shaft 27 and is
exposed by retracting sheath 25 relative to inner shaft 27. A
tapered nosecone 28, composed of a soft elastomeric material to
reduce trauma to the vessel during advancement of the device, is
mounted distally of expandable member 24. A stent 30, which
preferably comprises a plurality of separate or separable stent
segments 32, is disposed on expandable member 24 for expansion
therewith. A guidewire tube 34 is slidably positioned through a
guidewire tube exit port 35 in sheath 25 proximal to expandable
member 24. A guidewire 36 is positioned slidably through guidewire
tube 34, expandable member 24, and nosecone 28 and extends distally
thereof.
[0066] A handle 38 is attached to a proximal end 23 of the sheath
25. The handle 38 performs several functions, including operating
and controlling the catheter body 22 and the components included in
the catheter body. Various embodiments of a preferred handle and
additional details concerning its structure and operation are
described in co-pending U.S. patent application Ser. No. ______,
filed Jun. 8, 2005, (Attorney Docket No. 14592.4002), entitled
"Devices and Methods for Operating and Controlling Interventional
Apparatus," which application is hereby incorporated herein by
reference. Embodiments of another preferred handle and details
concerning its structure and operation are described in co-pending
U.S. application Ser. No. 10/746,466, filed Dec. 23, 2003 (Attorney
Docket No. 021629-002200US), entitled "Devices and Methods for
Controlling and Indicating the Length of an Interventional
Element," which application is also hereby incorporated herein by
reference.
[0067] The handle 38 includes a housing 39 that encloses the
internal components of the handle. The inner shaft 27 is preferably
fixed to the handle, while the outer sheath 25 is able to be
retracted and advanced relative to the handle 38. An adaptor 42 is
attached to the handle 38 at its proximal end, and is fluidly
coupled to the inner shaft 27 in the interior of the housing of the
handle 38. The adaptor 42 is configured to be fluidly coupled to an
inflation device, which may be any commercially available balloon
inflation device such as those sold under the trade name
"Indeflator.TM.", available from Guidant Corp. of Santa Clara,
Calif. The adaptor is in fluid communication with the expandable
member 24 via an inflation lumen in the inner shaft 27 to enable
inflation of the expandable member 24.
[0068] The outer sheath 25 and guidewire 36 each extend through a
slider assembly 50 located on the catheter body 22 at a point
between its proximal and distal ends. The slider assembly 50 is
adapted for insertion into and sealing within a hemostatic valve,
such as on an introducer sheath or guiding catheter, while allowing
relative movement of the outer sheath 25 relative to slider
assembly 50. The slider assembly 50 includes a slider tube 51, a
slider body 52, and a slider cap 53. These components are
illustrated in greater detail in FIGS. 16-19.
[0069] In particular, FIGS. 16 and 16A show the slider tube 51,
which comprises an elongated cylindrical member having a first
through-hole 51 a and a second through-hole 51b. The first
through-hole 51a has a size to provide a slidable passageway for
the catheter body 22, whereas the second through-hole 51b has a
size to provide a slidable passageway for the guidewire 34. The
slider tube 51 is preferably formed from a polymeric material, such
as PTFE, FEP, polyimide, nylon, or Pebax. The slider body 52 is
illustrated in FIGS. 17 and 17A-B. The slider body 52 is also an
elongated member having a cylindrical section 160 and a tapered
section 161. The tapered section 161 has an internal recess 161 a
that has an interior diameter that provides a snug fit with the
external surface of the slider tube 51. The cylindrical section 160
has an internal recess 160a that has an interior diameter that
provides a snug fit with the external surface of the slider cap 53.
The slider body 52 also includes a first through-hole 52a sized to
allow slidable passage of the catheter body 22, and a second
through-hole 52b sized to allow passage of the guidewire 34. The
slider body is preferably formed from a resilient, relatively
incompressible material, such as polycarbonate, and has an exterior
surface adapted for being clamped and sealed within a hemostasis
valve, preferably being smooth and cylindrical in shape. The slider
cap 53 is a relatively short cylindrical member having a first
through-hole 53a sized to allow slidable passage of the catheter
body 22, and a second through-hole sized to allow slidable passage
of the guidewire 34. The slider cap 53 has a size that provides a
snug fit with the internal recess 160a of the cylindrical section
160 of the slider body. The slider cap 53 is also preferably formed
of a resilient, relatively incompressible material, such as
polycarbonate.
[0070] A slider seal 54 is illustrated in FIG. 19. The slider seal
is a short, disc-shaped member having a size adapted to fit snugly
within the internal recess 160a of the cylindrical section 160 of
the slider body. The slider seal 54 includes a first through-hole
54a sized to allow fluidly sealed, slidable passage of the catheter
body 22, and a second through-hole 54b sized to allow fluidly
sealed, slidable passage of the guidewire 34. The slider seal is
preferably formed of a pliable, resilient material, such as a
polymeric material or a silicone compound that is capable of
providing a fluid-tight seal with the sheath and guidewire while
allowing slidable movement thereof.
[0071] The slider assembly 50 is constructed by installing the
proximal end of the slider tube 51 into the internal recess 161 a
of the tapered portion 161 of the slider body, taking care to align
the first and second through-holes of each member appropriately.
The slider seal 54 is installed in the internal recess 160a of the
cylindrical portion 160 of the slider body, and the slider cap 53
is placed over the slider seal 54 within the internal recess 160a,
again taking care to ensure that the first and second through-holes
of each component are properly aligned. The components are then
bonded together by heating or by use of adhesives or other suitable
means. The completed slider assembly 50 is then placed over the
catheter body 22 and the guidewire 34 as shown in FIG. 1.
[0072] Referring now to FIGS. 2A-2B, 3 and 4, which show a distal
portion of the stent delivery catheter in cross-section, it may be
seen that sheath 25 may be extended up to nosecone 28 to fully
surround expandable member 24 and stent segments 32. A garage 55 is
attached to the outer sheath 25 at the distal end 57 of the sheath.
The garage 55 is a generally cylindrical member having a relatively
high circumferential strength such that it is able to prevent the
expandable member 24 from inflating when the garage is extended
over the inflatable member 24. The garage 55 preferably has a
length at least as long as one of the stent segments 32 carried by
the catheter, but preferably less than the combined length of two
such stent segments. The garage 55 is shown in more detail in FIGS.
9-11, and is described more fully below. A radiopaque marker 56 is
preferably formed integrally with or attached to the distal end of
the garage 55 to facilitate visualization of the position of the
sheath 25 using fluoroscopy. The radiopaque marker 56 may have an
axial length selected to provide a visual reference for determining
the appropriate distance for stent segment separation, e.g., 2-4
mm, as described below.
[0073] The outer sheath 25 further includes a valve member 58
within the garage 55 preferably spaced proximally from the distal
end 57 a distance equal to, slightly larger than, or slightly
smaller than the length of one of the stent segments 32. For
example, in a preferred embodiment, each stent segment 32 has a
length of about 4 mm, and the valve member 58 is located
approximately 5 mm from the distal end 57 of the sheath or the
distal end of the garage member 55. In other embodiments, the valve
member 58 may be spaced from the distal end 57 a distance equal to
about 1/4-3/4 of the length of one stent segment 32, more
preferably one-half the length of one stent segment 32. Valve
member 58 preferably comprises a necked-down circumferential waist
or inwardly extending ring-shaped flange 60 configured to
frictionally engage stent segments 32 and thereby restrict the
sliding movement of stent segments 32 distally relative to sheath
25. Flange 60 may be a polymeric or metallic material integrally
formed with sheath 25 or, preferably, with the garage 55, or a
separate annular member bonded or otherwise mounted to the interior
of the sheath 25 or the garage 55. The geometry of flange 60 may be
toroidal with circular cross-section (like an O-ring) or it may
have another cross-sectional shape such as triangular, trapezoidal,
or pyramidal. Preferably flange 60 is a polymer such as silicone or
urethane sufficiently soft, compliant, and resilient to provide
frictional engagement with stent segments 32 without damaging the
stent segment or any coating deposited thereon. Valve member 58
will extend radially inwardly a sufficient distance to engage the
exterior of stent segments 32 with sufficient force to allow the
line of stent segments 32 remaining within sheath 25 to be
retracted proximally with sheath 25 so as to create spacing
relative to those stent segments disposed distally of sheath 25 for
deployment. At the same time, valve member 58 should not exert so
much force that it removes or damages the coating on the exterior
surface of stent segments 32 as sheath 25 is retracted relative to
the stent segments to expose a desired number of stent segments 32.
In a preferred embodiment, stent segments 32 have an outer diameter
of about 0.040-0.050 in. (including coating) and sheath 25 and
garage 55 have inner diameter 0.041-0.051 in. so as to provide
clearance of about 0.001 in. with stent segments 32. Valve member
58 has a preferred inner diameter about 0.003-0.008 in. less than
that of garage 55, or about 0.033-0.048'', so as to provide an
interference fit with stent segments 32. Valve member 58 will
preferably exert a force of about 0.5-5 lbs. on a stent segment 32
positioned within it. Various embodiments of valve member 58 are
described in copending application Ser. No. 10/412,714, Filed Apr.
10, 2003 (Attorney Docket No. 21629-000330), which is incorporated
herein by reference.
[0074] FIGS. 9-11 illustrate the garage 55, the radiopaque marker
56, and the valve member 58 in greater detail. The garage 55 is a
cylindrical member that is preferably mounted to the distal end of
the outer sheath 25. FIG. 9 illustrates the garage 55 as it is
oriented surrounding the stent segments 32 aligned over the inner
shaft. The distal portion of the outer sheath 25 is shown stripped
away in FIG. 9 to reveal the orientation of the garage 55. The
cylindrical garage 55 is preferably formed of a metallic,
polymeric, or other material and in a geometry to provide high
radial strength and high axial flexibility. Superelastic alloys are
preferred materials. A preferred garage material is Nitinol.
[0075] The structure of the garage 55 is illustrated in FIG. 10, in
which the garage 55 is shown in a planar form for clarity. The
garage 55 is preferably laser cut from a tube, but may also be cut,
stamped, or otherwise formed from a sheet of material.
[0076] A number of cut-outs or windows 59 are preferably formed in
the body of the garage to increase its axial flexibility.
Preferably, the garage 55 is constructed in a manner and of
materials that allow it to bend about a transverse axis. Although
the number, size, and shape of the cut-outs 59 may vary, the
illustrated embodiment includes a preferred form. The distal end
55a of the garage 55 is provided with no cut-outs in order to
provide the greatest radial strength at the distal end of the
sheath, where the restraining force against the expandable member
24 is the greatest. A pair of first cut-outs 59a having oval or
rectangular shape are formed a short distance from the distal end
55a of the garage, the pair of first cut-outs 59a being aligned
circumferentially around the periphery of the garage. A series of
narrow second cut-outs 59b having a linear or slot-like shape are
formed over the central portion of the body of the garage 55.
Preferably, the second cut-outs 59b are provided in a staggered
formation to provide greater axial flexibility over the central
portion of the garage. A series of third cut-outs 59c are located
just proximally of the central portion of the garage. The third
cut-outs 59c are of a similar size and shape to the first cut-outs
59a, but are circumferentially staggered from the first cut-outs
59a. A series of fourth rectangular or oval-shaped cut-outs 59d are
located just proximally of the third cut-outs, and are both
narrower and shorter than the third cut-outs 59c. Finally, a series
of fifth cut-outs 59e having a hexagonal shape are provided near
the proximal end 55b of the garage. Each of the fifth cut-outs 59e
is substantially wider (i.e., greater longitudinal length) than the
other cut-outs 59a-d. As noted below, the position of the fifth
cut-outs corresponds with the location of the valve member 58.
[0077] Turning to FIG. 11, the garage 55 is shown supported on a
proximal mandrel 150 and a distal mandrel 152 to facilitate
attachment of the valve member 58 and sheath 25 thereto. The
proximal mandrel is provided with an indentation or concavity
adapted to receive and retain the valve member 58 in place for the
purpose of attaching the valve member 58 to the garage 55 and outer
sheath 25. The radiopaque marker 56 may be placed over the distal
end 55a of the garage 55. After the foregoing components have been
properly aligned, the outer sheath 25 is attached to the proximal
end 55b of garage 55, preferably by placing a piece of shrink
tubing over the garage and distal end of the outer sheath and
heating the assembly. The garage 55 is thereby covered with a
polymer material about its exterior. Of course various other
attachment techniques may be used including heat treatment,
adhesives, or other methods known to those skilled in the art.
[0078] As thus described, the sheath 25 has a distal extremity 62
configured to surround expandable member 24 and stent segments 32
disposed thereon when in an unexpanded configuration. Distal
extremity 62 extends proximally to a junction 63, preferably
aligned with the location of guidewire tube exit port 35, where
distal extremity 62 is joined to a proximal extremity 64 that
extends proximally to handle 38 (see FIG. 1). In a preferred
embodiment, distal extremity 62 has a length of about 15-35 cm and
proximal extremity 64 as a length of about 100-125 cm. Proximal
extremity 64 may be constructed of a variety of biocompatible
polymers, metals, or polymer/metal composites, preferably being
stainless steel or Nitinol. Distal extremity 62 may be a polymer
such as PTFE, FEP, polyimide, nylon, or Pebax, or combinations of
any of these materials. In a preferred form, the distal extremity
62 comprises a composite of nylon, PTFE, and polyimide. The distal
extremity is preferably reinforced with a metallic or polymeric
braid to resist radial expansion when expandable member 24 is
expanded. Sheath 25 may further have a liner surrounding its
interior of low friction material such as PTFE to facilitate
relative motion of sheath 25, stent segments 32, and pusher tube
86.
[0079] Preferably, proximal extremity 64 has a smaller transverse
dimension than distal extremity 62 to accommodate the added width
of guidewire tube 34 within the vessel lumen, as well as to
maximize flexibility and minimize profile. In one embodiment, shown
in FIG. 3, distal extremity 62 is a tubular member having a first
outer diameter, preferably about 1.0-1.5 mm, and proximal extremity
64 is a tubular member having a second, smaller outer diameter,
preferably about 0.7-1.0 mm. At the junction of proximal extremity
64 with distal extremity 62, a proximally-facing crescent-shaped
opening 65 is formed between the two tubular members that creates
guidewire tube exit port 35. Excess space within crescent-shaped
opening 65 may be filled with a filler material such as adhesive or
a polymeric material (e.g., Pebax).
[0080] In an alternative embodiment (not shown), a hole is formed
in the sidewall of distal extremity 62 or proximal extremity 64 to
create guidewire tube exit port 35. Proximally of guidewire tube
exit port 35, the wall of sheath 25 adjacent to guidewire tube 34
is flattened or collapsible inwardly thereby reducing the
transverse dimension of sheath 25 to accommodate the width of
guidewire tube 34.
[0081] Guidewire tube 34 is slidably positioned through guidewire
tube exit port 35. The guidewire tube exit port 35 may be
configured to provide a total or partial fluid seal around the
periphery of guidewire tube 34 to limit blood flow into the
interior of sheath 25 and to limit leakage of saline (or other
flushing fluid) out of sheath 25. This may be accomplished by
sizing guidewire tube exit port 35 appropriately so as to form a
fairly tight frictional seal around guidewire tube 34 while still
allowing the sliding motion thereof relative to sheath 25.
Alternatively an annular sealing ring may be mounted in guidewire
tube exit port 35 to provide the desired seal. Preferably, however,
the guidewire tube exit port 35 is not totally fluid sealed, so as
to provide a slight leakage or fluid flow to provide the ability to
flush the distal extremity 62 of the catheter.
[0082] Guidewire tube exit port 35 will be positioned to provide
optimal tracking of stent delivery catheter 20 through the
vasculature and maximizing the ease with which the catheter can be
inserted onto and removed from a guidewire to facilitate catheter
exchanges. Usually, guidewire tube exit port 35 will be positioned
at a location proximal to expandable member 24 when sheath 25 is
extended fully distally up to nosecone 28, but a distance of no
more than one-half the length of sheath 25 from distal end 57. In
preferred embodiments for coronary applications, guidewire tube
exit port 35 is spaced proximally a distance of about 20-35 cm from
the distal end 57 of sheath 25.
[0083] Guidewire tube 34 should extend proximally from guidewire
tube exit port 35 a distance at least as long as the longest
possible stent that may be deployed, e.g., 30-200 mm depending upon
the application, to allow for retraction of sheath 25 that distance
while retaining a portion of guidewire tube 34 external to sheath
25. Preferably the guidewire tube 34 extends proximally a distance
of about 35 to about 70 mm from the guidewire tube exit port 35
when sheath 25 is in a fully distal position, with the proximal end
thereof disposed a distance of about 23-50 cm from the distal tip
of nosecone 28. Where stent delivery catheter 20 is to be
positioned through a guiding catheter, the proximal end of
guidewire tube 34 will preferably be positioned so as to be within
the guiding catheter when expandable member 24 is positioned at the
target site for stent deployment. Guidewire tube 34 is preferably a
highly flexible polymer such as PTFE, FEP, polyimide, or Pebax, and
may optionally have a metal or polymer braid or fiber embedded in
it to increase kink-resistance and tensile strength.
[0084] Inner shaft 27 forms an inflation lumen 66 that is in
communication with interior of expandable member 24. The inner
shaft 27 may be formed of a polymer material such as PTFE, FEP,
polyimide, or Pebax, or the inner shaft 27 may be a metal such as
stainless steel or Nitinol.
[0085] Expandable member 24 has an expandable balloon member 70
that is joined to a non-expandable tubular leg 72. Expandable
balloon member 70 is a semi-compliant polymer such as Pebax,
polyurethane, or Nylon. Non-compliant, fully elastic, or other
materials such as PTFE may also be used. Preferably, the compliance
of the balloon member allows the expanded diameter of balloon
member 70 to be adjusted by selecting the appropriate inflation
pressure delivered thereto, thereby allowing customization of the
deployed diameter of stent segments 32. For example, in one
embodiment, balloon member 70 may be inflated to a pressure of
between about 5 and about 12 atmospheres, allowing the deployed
stent diameter to be adjusted from about 2.0 mm to 4.0 mm. Of
course, larger and smaller stent diameters are also possible by
utilizing appropriate stent geometry and applying suitable
inflation pressures. Tubular leg 72 is preferably a polymer such as
polyimide, PTFE, FEP, polyurethane, or Pebax and may optionally be
reinforced with a metal or polymer braid or metal or polymer
fibers. Tubular leg 72 has an open proximal end 74 through which
guidewire tube 34 extends. Proximal end 74 of tubular leg 72 is
fixed to distal end 68 of inner shaft 27 and to guidewire tube 34,
forming a fluid-tight seal. Guidewire tube 34 passes through the
interior of balloon member 70 and is mounted to nosecone 28,
thereby providing a passage through the distal portion of catheter
body 22 through which guidewire 36 may pass. Balloon member 70 has
a distal end 76 that extends over an annular stop 78, which is
mounted to the distal end of guidewire tube 34 and/or nosecone 28.
Distal end 76 of balloon member 70 may be bonded to stop 78,
guidewire tube 34, and/or nosecone 28. The stop 78 has a size and
shape selected to engage stent segment 32 and provide a stop
against which stent segments 32 can be located in the ideal
deployment position without being pushed beyond the distal end of
balloon member 70. Additional details concerning stent stops
suitable for use in the devices and methods described herein are
disclosed in U.S. patent application Ser. No. 10/884,616, filed
Jul. 2, 2004, (Atty. docket 21629-000360), which is hereby
incorporated by reference herein.
[0086] Preferably, the stop 78 has a partial cylindrical shape,
rather than a full cylindrical shape, as a relief to reduce
interference with garage 55. For example, FIGS. 9 and 9A illustrate
the stop 78 having a flat portion 81 formed on the opposed lateral
surfaces of the stop 78. A similar flat portion may be formed on
the upper and lower sides of the stop 78. The provision of flat
portions on the stop 78 allows the stop 78 to limit distal movement
of the stent segments 32, while reducing interference between stop
78 and the interior of garage 55.
[0087] Optionally, within the interior of balloon member 70 an
annular base member 80 is mounted to guidewire tube 34 and has a
diameter selected to urge balloon member 70 against stent segments
32 in their unexpanded configuration, thereby providing frictional
engagement with stent segments 32. This helps to limit unintended
sliding movement of stent segments 32 on balloon member 70. Base
member 80 may be made of a soft elastomer, foam, or other
compressible material.
[0088] An additional option or alternative structure for limiting
unintended sliding or movement of the stent segments is the
provision on the distal exterior portion of the expandable member
24 of a layer of material 84 having a high coefficient of friction
so as to frictionally engage the stent segments 32. See FIGS.
12A-C. For example, a layer of a polymeric material 84, such as
polyurethane, will prevent the stent segments 32 from sliding off
the distal end of the balloon, and will cause the stent segments 32
to stop in the desired location near the distal end of the
expandable member 24. The layer of material 84 is preferably formed
over the entire circumference of the distal end of the expandable
member 24, as shown in the Figures, but may alternatively be placed
only at spaced intervals around the periphery. The material layer
84 is preferably formed of elastomeric materials and in a manner
that allows it to expand and contract as the expandable member 24
expands and contracts. For example, the material layer 84 may be
applied by dipping the expandable member 24 in a liquid polymer, by
spraying, or by attaching a sheet or tube of material over the
expandable member 24 by adhesive or heat treatment. As the stent
segments 32 move distally relative to the expandable member 24 in
its contracted state, the distal end of the most distal stent
segment will come into contact with the layer of material 84 and
the friction force encountered by the stent segment 32 will
increase. This will inhibit or prevent additional relative movement
between the stent segment 32 and the expandable member 24. In
addition, the increased frictional resistance may serve as a
tactile indicator to the user of the position of the stent segment
32 relative to the expandable member 24. Material layer 84 may be
of equal thickness along it length, or the thickness of the
material layer 84 may gradually increase in the distal direction to
provide gradually increasing interference with stent segments 32.
Material layer 84 may have an outer surface at the same height as
the outer surface of expandable member 24 to provide a smooth
transition therebetween, or material layer 84 may be of greater
height to provide a step that enhances engagement with stent
segments 32.
[0089] In a preferred embodiment as shown in FIG. 12C, expandable
member 24 is molded with a circumferential channel, stepped
geometry, and/or with reduced wall thickness near its distal end so
as to have a smaller outer diameter in the region where the
material layer 84 is to be applied to accommodate the thickness of
material layer 84. In this way, the outer wall of the expandable
member 24 and material layer 84 will be smooth and continuous
without an abrupt change in elevation, allowing stent segments 32
to slide smoothly from the expandable member 24 to the material
layer 84. Alternatively, expandable member 24 and/or material layer
84 may have an outer diameter or wall thickness that is stepped
outwardly or that gradually increases in the distal direction so as
to increase the frictional resistance with stent segments 32. In
alternative embodiments, material layer 84 may have surface
features such as bumps, ridges, projections, or scales to increase
friction against stent segments 32.
[0090] Annular radiopaque markers 82 may be mounted to the
guidewire tube 34, facilitating visualization of the location of
balloon member 70 with fluoroscopy and enabling appropriate
positioning of stent segments 32 on balloon member 70. Referring to
FIG. 2C, the radiopaque markers 82 are preferably located at
regular intervals along the length of the guidewire tube 34. In a
particularly preferred form, the radiopaque markers 82 are spaced
at intervals that are related to the length of individual stent
segments 32, such as being at intervals equal to the stent segment
lengths, one-half of stent segment length, double stent segment
length, or the like. Stated otherwise, the distance between the
distal ends of adjacent markers 82 (or the proximal ends of
adjacent markers 82, or the mid-points of adjacent markers 82,
etc.) are provided equal to the stent segment lengths, one-half of
stent segments length, double stent segment length, or the like.
Locating multiple radiopaque markers 82 on the guidewire tube 34 at
regularly spaced intervals provides a visual reference for
determining the location and number of stent segments 32 on
expandable member 24 under fluoroscopy. Further, the length of
expandable member 24 and stent segments 32 exposed during
retraction of sheath 25 may be determined under fluoroscopy by
observing the position of marker 56 on garage member 55 relative to
marker(s) 82 on guidewire tube 34. Alternatively, only a single
marker 82 at or near the distal end of balloon member 70 may be
used, or markers may be placed at both the distal end and proximal
end of the base member 80, or markers may be placed at other
locations on nosecone 28, guidewire tube 34, or inner shaft 27.
Such markers may be made of various radiopaque materials such as
platinum/iridium, tantalum, gold, and other materials.
[0091] Stent segments 32 are slidably positioned over balloon
member 70. Depending upon the number of stent segments 32 loaded in
stent delivery catheter 20, stent segments 32 may be positioned
over both balloon member 70 and tubular leg 72. In an exemplary
embodiment, each stent segment is about 2-20 mm in length, more
preferably 2-8 mm in length, and 3-50 stent segments may be
positioned end-to-end in a line over balloon member 70 and tubular
leg 72. Stent segments 32 preferably are in direct contact with
each other, but alternatively separate spacing elements may be
disposed between adjacent stent segments, the spacing elements
being movable with the stent segments along balloon member 70. Such
spacing elements may be plastically deformable or self-expanding so
as to be deployable with stent segments 32 into the vessel, but
alternatively could be configured to remain on balloon member 70
following stent deployment; for example, such spacing elements
could comprise elastic rings which elastically expand with balloon
member 70 and resiliently return to their unexpanded shape when
balloon member 70 is deflated. The spacing elements could be pushed
to the distal end of balloon member 70 against stop 78 as
additional stent segments 32 are advanced distally.
[0092] Stent segments 32 are preferably a malleable metal so as to
be plastically deformable by expandable member 24 as they are
expanded to the desired diameter in the vessel. Alternatively,
stent segments 32 may be formed of an elastic or super elastic
shape memory material such as Nitinol so as to self-expand upon
release into the vessel by retraction of sheath 25. Stent segments
32 may also be composed of polymers or other suitable biocompatible
materials including bioabsorbable or bioerodable materials. In
self-expanding embodiments, expandable member 24 may be eliminated
or may be used for predilatation of a lesion prior to stent
deployment or for augmenting the expansion of the self-expanding
stent segments.
[0093] In preferred embodiments, stent segments 32 are coated with
a drug that inhibits restenosis, such as Rapamycin, Paclitaxel,
Biolimus A9 (available from BioSensors International), analogs,
prodrugs, or derivatives of the foregoing, or other suitable agent,
preferably carried in a durable or bioerodable polymeric or other
suitable carrier material. Alternatively, stent segments 32 may be
coated with other types of drugs and therapeutic materials such as
antibiotics, thrombolytics, anti-thrombotics, anti-inflammatories,
cytotoxic agents, antiproliferative agents, vasodilators, gene
therapy agents, radioactive agents, immunosuppressants, and
chemotherapeutics. Several preferred therapeutic materials are
described in U.S. Published Patent Application No. 2005/0038505,
entitled "Drug-Delivery Endovascular Stent and Method of Forming
the Same," filed Sep. 20, 2004, which application is hereby
incorporated by reference herein. Such materials may be coated over
all or a portion of the surface of stent segments 32, or stent
segments 32 may include apertures, holes, channels, pores, or other
features in which such materials may be deposited. Methods for
coating stent segments 32 are described in the foregoing published
patent application. Various other coating methods known in the art
may also be used, including syringe application, spraying, dipping,
inkjet printing-type technology, and the like.
[0094] Stent segments 32 may have a variety of configurations,
including those described in copending application Ser. No.
10/738,666, filed Dec. 16, 2003 (Attorney Docket No. 21629-000510),
which is incorporated herein by reference. Other preferred stent
configurations are described below. Stent segments 32 are
preferably completely separate from one another without any
interconnections, but alternatively may have couplings between two
or more adjacent segments which permit flexion between the
segments. As a further alternative, one or more adjacent stent
segments may be connected by separable or frangible couplings that
are separated prior to or upon deployment, as described in
co-pending application Ser. No. 10/306,813, filed Nov. 27, 2002
(Attorney Docket No. 21629-000320), which is incorporated herein by
reference.
[0095] A pusher tube 86 is slidably disposed over inner shaft 27.
The structure of the pusher tube 86 is illustrated in FIG. 13, and
its location within the catheter body 22 is best shown in FIGS.
2A-B. The pusher tube 86 contains three primary sections, a distal
extension 88, a ribbon portion 89, and a proximal portion 90. The
proximal portion 90 extends from the handle 38 over the inner shaft
27 and to the ribbon portion 89. The proximal portion 90 is
preferably formed of a tubular material to provide high column
strength but adequate flexibility to extend through the vasculature
from an access site to the coronary ostia or other target vascular
region. A preferred material is stainless steel hypotube. The
ribbon portion 89 of the pusher tube corresponds with the location
of the guidewire exit port 35 on the outer sheath 25. The ribbon
portion 89 is formed of a partial-tube, see, e.g., FIG. 13A, in
order to provide an opening to allow the guidewire tube 34 to pass
through to the exit port 35. The proximal portion of the ribbon
portion 89 is formed out of the same tubular material that makes up
the proximal portion 90 of the pusher tube, e.g., stainless steel
hypotube. The proximal portion of the ribbon portion 89 is joined
to the distal portion of the ribbon 89, such as by a weld 91 or the
ribbon portion and proximal portion may be formed from the same
hypotube which is laser cut in the appropriate geometry. The distal
extension 88 is preferably formed of a slotted tube of rigid
material, such as stainless steel or Nitinol. The slotted tube
making up the distal extension 88 includes a number of cylindrical
rings 92 interconnected by longitudinal connectors 93, thereby
defining a plurality of transverse slots 97 arranged in pairs along
the length of the distal extension. Each pair of slots is disposed
opposite one another on distal extension 88, thus defining a pair
of opposing, longitudinal connectors 93. The longitudinal
connectors 93 are flexible so as to be capable of bending around a
transverse axis. Each pair of transverse slots 97 is oriented at 90
degrees relative to the adjacent pair of slots 97, so that the
pairs of longitudinal connectors 93 alternate between those
oriented vertically and those oriented horizontally. This allows
distal extension 88 to bend about either a horizontal and vertical
transverse axes, thus providing a high degree of flexibility. Of
course, the pairs of transverse slots 97 could be oriented at
various angles relative to adjacent pairs to provide flexibility
about more than two axes. The slots provided in the slotted tube
allows the distal extension 88 to be more axially flexible than it
would be without the slots, while still retaining high column
strength. It is preferable to provide transverse slots 97 and
cylindrical rings 92 that each have a width that is approximately
the same as the length of a stent segment 32. In addition or
alternatively, the transverse slots 97 and cylindrical rings 92 may
be spaced apart by a known fraction or multiple of the stent
segment length. In this way, a detent mechanism may be provided on
the interior surface of the sheath 25, with one or more detents
that releasably engage the cylindrical rings 92 formed in the
distal extension 88 to provide a tactile feedback based upon the
distance that the outer sheath 25 is retracted relative to pusher
tube 86. A nesting tip 94 is formed on the distal end of the distal
extension 88. The nesting tip preferably includes a plurality of
fingers shaped and oriented to engage and interleave with the
proximal end of the most proximal stent segment 32. As described
elsewhere herein, stent segments 32 preferably have axial
extensions or projections on each end which interleave with those
on the adjacent stent segment. Tip 94 of pusher tube 86 preferably
has a geometry with axial projections similar to or complementary
to those of stent segments 32 so as to interleave therewith.
[0096] Preferably, the proximal portion 90 of the pusher tube has a
diameter that is smaller than the diameter of the distal extension
88. Thus, the stainless steel hypotube material making up the
proximal portion 90 of the pusher tube and part of the ribbon
portion 89 may have a first diameter, while the slotted tube making
up the distal extension 88 and the distal portion of the ribbon 89
may have a second, larger diameter. As noted above, the slotted
tube and the hypotube are preferably joined by a weld 91 formed in
the ribbon portion 89.
[0097] As best shown in FIGS. 2A-B, the pusher tube 86 extends
longitudinally within the outer sheath 25 and over the inner shaft
27 through most of the length of the catheter body 22. The distal
extension 88 is slidable over the tubular leg 72 and engages the
stent segment 32 at the proximal end of the line of stent segments
32. At its proximal end (not shown), the pusher tube 86 is coupled
to an actuator associated with the handle 38 (see FIG. 1). In this
way, the pusher tube 86 can be advanced distally relative to inner
shaft 27 to urge the stent segments 32 distally over the expandable
member 24 (or, alternatively, the pusher tube 86 may be held in
position while retracting the expandable member 24 relative to
stent segments 32) until the stent segments engage the stop 78. In
addition, the pusher tube 86 can be used to hold the stent segments
32 in place on the expandable member 24 while the sheath 25 is
retracted to expose a desired number of stent segments 32, as shown
in FIG. 2B. As noted above, the proximal portion 90, ribbon portion
89, and distal extension 88 of the pusher tube are preferably
constructed of stainless steel, but they may alternatively be
constructed of a variety of biocompatible polymers, metals,
polymer/metal composites, alloys, or the like.
[0098] It can be seen that with sheath 25 retracted a desired
distance, expandable member 24 is allowed to expand when inflation
fluid is delivered through inflation lumen 66, thereby expanding a
desired number of stent segments 32 exposed distally of sheath 25.
The remaining portion of expandable member 24 and the remaining
stent segments 32 within sheath 25 are constrained from expansion
by sheath 25.
[0099] FIG. 2B further illustrates that when sheath 25 is retracted
relative to expandable member 24, guidewire tube exit port 35
becomes further away from the point at which guidewire 36 exits the
proximal end 74 of tubular leg 72, increasing the distance that
guidewire 36 must pass within the interior of sheath 25.
Advantageously, guidewire tube 34 provides a smooth and continuous
passage from the tubular leg 72 through guidewire tube exit port
35, eliminating any problems that might result from changing the
alignment of the two. This is particularly important in the present
invention where the stent delivery catheter may carry a large
number of stent segments 32 and sheath 25 may be retracted a
substantial distance relative to expandable member 24, resulting in
substantial misalignment of guidewire tube exit port 35 relative to
tubular leg 72.
[0100] In order to confirm the positioning of the stent segments 32
on the expandable member 24, fluoroscopy is used to visualize the
stent segments 32 relative to the markers 82 located on the inner
shaft 27. In addition, by fluoroscopic visualization of the marker
56 located on the garage 55 at the distal end of the outer sheath
25, the user can see the extent of retraction of the sheath 25
relative to the expandable member 24 and view the location of the
exposed stent segments 32 relative to the sheath 25. Visualization
of the stent segments 32 is further enhanced with the use of
radiopaque markers and/or materials in or on the stent segments
themselves. Markers of radiopaque materials may be applied to the
exterior of stent segments 32, e.g, by applying a metal such as
gold, platinum, a radiopaque polymer, or other suitable coating or
mark on all or a portion of the stent segments. Examples of such
markers are illustrated in FIGS. 14A-B. In those Figures,
radiopaque markers 95 are attached to a plurality of circular
openings formed in the body of the stent segment 32. Six such
markers are formed in a circumferentially aligned pattern in the
FIG. 14A example, while three markers are formed in another
circumferentially aligned pattern in the FIG. 14B example. The
markers may be discs, buttons, or other members that are welded in
place, or they may be provided as rivets or rivet-type members that
are installed in a sized hole or eyelet. Alternatively, stent
segments 32 may include a radiopaque cladding or coating or may be
composed of radiopaque materials such as L-605 cobalt chromium
(ASTM F90), other suitable alloys containing radiopaque elements,
or multilayered materials having radiopaque layers. See, for
example, FIGS. 15A-C, where three patterns of radiopaque coatings
are illustrated. In FIG. 15A, a coating 96 of radiopaque material
is provided in a broad circumferential center stripe on the stent
segment 32. In FIGS. 15B and C, smaller circumferential stripes of
radiopaque coatings 96 are formed on the proximal and distal ends
of the stent segment 32, such as being formed only on the axial
projection portions of the stent segment 32 (see FIG. 15C). In yet
another alternative, stent segments 32 may have a geometry
conducive to fluoroscopic visualization, such as having struts of
greater thickness, sections of higher density, or overlapping
struts.
[0101] Preferably, the radiopaque markers are configured so as to
provide an indication of the number, location, and/or relative
spacing of each stent segment 32 when deployed end-to-end in a line
in a vessel or other body lumen. This allows the operator to
determine how many stent segments 32 have been deployed at a
vascular site, and the spacing between adjacent stent segments 32.
The radiopaque markers allow the operator to visualize with
fluoroscopy the divisions between adjacent stent segments 32 by
observing radiopaque markers on the ends and/or a middle portions
of each stent segment 32. For example, in the embodiment of FIG.
15D, the operator may visualize a central stripe on each segment to
allow an accounting of the number and location of deployed segments
32. In the embodiments of FIG. 1SE, the operator may visualize two
adjacent radiopaque stripes where two segment ends are disposed
side-by-side. If the segments are close together, the operator sees
a single wide stripe, while if the segments are separated by a gap,
the operator may see two parallel stripes, thus providing an
indication of the segment spacing as well as number.
[0102] Some of the possible materials that may be used in stent
segments 32 include (by ASTM number):
[0103] F67-00 Unalloyed Titanium
[0104] F75-01 Cobalt-28 Chromium-6 Molybdenum Alloy
[0105] F90-01 Wrought Cobalt-20 Chromium-15 Tungsten-10 Nickel
Alloy
[0106] F136-02a Wrought Titanium-6 Aluminum-4 Vanadium ELI
Alloy
[0107] F138-00, F139-00 Wrought 18 Chromium-14 Nickel-2.5
Molybdenum Stainless Steel Bar or Sheet
[0108] F560-98 Unalloyed Tantalum
[0109] F562-02 Wrought 35 Cobalt-35 Nickel-20 Chromium-10
Molybdenum Alloy
[0110] F563-00 Wrought Cobalt-20 Nickel-20 Chromium 3.5
Molybdenum-3.5 Tungste-5 Iron Alloy
[0111] F688 Wrought Cobalt-35 Nickel-20 Chromium-10 Molybdenum
Alloy
[0112] F745-00 18 Chromium-12.5 Nickel-2.5 Molybdenum Stainless
Steel
[0113] F799-02 Cobalt-28 Chromium-6 Molybdenum Alloy
[0114] F961-96 Cobalt-35 Nickel-20 Chromium-10 Molybdenum Alloy
[0115] F1058-02 Wrought 40 Cobalt-20 Chromium-16 Iron-15 Nickel-7
Molybdenum Alloy
[0116] F1091-02 Wrought Cobalt-20 Chromium-15 Tungsten-10 Nickel
Alloy
[0117] F1108 Titanium-6 Aluminum-4 Vanadium Alloy
[0118] F1295-01 Wrought Titanium-6 Aluminum-7 Niobium Alloy
[0119] F1314-01 Wrought Nitrogen-strengthened 22 Chromium-13
Nickel-5 Manganese-2.5 Molybdenum Stainless Steel Alloy
[0120] F1241-99 Unalloyed Titanium Wire
[0121] F1 350-02 Wrought 18 Chromium-14 Nickel-2.5 Molybdenum
Stainless Steel Wire
[0122] F1377-98a Cobalt-28 Chromium-6 Molybdenum Powder coating
[0123] F1472-02a Wrought Titanium-6 Aluminum-4 Vanadium Alloy
[0124] F1537-00 Wrought Cobalt-28 Chromium-6 Molybdenum Alloy
[0125] F1580-01 Titanium and Titanium-6 Aluminum-4 Vanadium Alloy
Powder coating
[0126] F1586-02 Wrought Nitrogen Strengthened 21 Chromium-10
Nickel-3 Mnaganese-2.5 Molybdenum Stainless Steel Bar
[0127] F1713-96 Wrought Titanium-13 Niobium-13 Zirconium Alloy
[0128] F1813-01 Wrought Titanium-12 Molybdenum-6 Zirconium-2 Iron
Alloy
[0129] F2063-00 Wrought Nickel-Titanium Shape Memory Alloys
[0130] F2066-01 Wrought Titanium-15 Molybdenum Alloy
[0131] F2146-01 Wrought Titanium-3 Aluminum-2.5 Vanadium Alloy
Seamless Tubing
[0132] F2181-02a Wrought Stainless Steel Tubing.
[0133] FIGS. 5A-B illustrate a portion of a first embodiment of a
stent segment 32. The Figures illustrate a portion of the stent
segment 32 in a planar shape for clarity. The stent segment 32
includes two parallel rows 98A, 98B of I-shaped cells 100 formed
into a cylindrical shape around an axial axis A. Each cell 100
includes upper and lower axial slots 102 and a connecting
circumferential slot 104. The upper and lower slots 102 are bounded
by upper axial struts 106, lower axial struts 107, curved outer
ends 108 and curved inner ends 110. Each circumferential slot 104
is bounded by an outer circumferential strut 109 and an inner
circumferential strut 111. Each I-shaped cell 100 is connected to
the adjacent I-shaped cell 100 in the same row 98A or 98B by a
circumferential connecting strut 113. All or a portion of cells 100
in row 98A merge or join with cells 100 in row 98B at the inner
ends 110, which are integrally formed with the inner ends 110 of
the adjacent cells 100.
[0134] In a preferred embodiment, a spacing member 112 extends
outwardly in the axial direction from a selected number of outer
circumferential struts 109 and/or connecting struts 113. Spacing
member 112 preferably itself forms a subcell 114 in its interior,
but alternatively may be solid without any cell or opening therein.
For those spacing members 112 attached to outer circumferential
struts 109, subcell 114 preferably communicates with I-shaped cell
100. Spacing members 112 are configured to engage the curved outer
ends 108 of an adjacent stent segment 32 so as to maintain
appropriate spacing between adjacent stent segments. In one
embodiment, spacing members 112 have outer ends 116 with two
spaced-apart protrusions 118 that provide a cradle-like structure
to index and stabilize the curved outer end 108 of the adjacent
stent segment. Preferably, spacing members 112 have an axial length
of at least about 10%, more preferably at least about 25%, of the
long dimension L of I-shaped cells 100, so that the I-shaped cells
100 of adjacent stent segments are spaced apart at least that
distance. Because spacing members 112 experience little or no axial
shortening during expansion of stent segments 32, this minimum
spacing between stent segments is maintained both in the unexpanded
and expanded configurations.
[0135] FIG. 5B shows stent segment 32 of FIG. 5A in an expanded
configuration. It may be seen that cells 100 are expanded so that
upper and lower slots 102 are diamond shaped with circumferential
slots 104 remaining basically unchanged. This results in some axial
shortening of the stent segment, thereby increasing the spacing
between adjacent stent segments. The stent geometry is optimized by
balancing the amount of axial shortening and associated
inter-segment spacing, the desired degree of vessel wall coverage,
the desired metal density, and other factors. Because the stent is
comprised of multiple unconnected stent segments 32, any desired
number from 2 up to 10 or more stent segments may be deployed
simultaneously to treat lesions of any length. Further, because
such segments are unconnected to each other, the deployed stent
structure is highly flexible and capable of deployment in long
lesions having curves and other complex shapes.
[0136] As an additional feature, circumferential slots 104 provide
a pathway through which vessel side branches can be accessed for
catheter interventions. Should stent segment 32 be deployed at a
location in which it covers the ostium of a side branch to which
access is desired, a balloon dilatation catheter may be positioned
through circumferential slot 104 and expanded. This deforms
circumferential struts 109, 111 axially outward, thereby expanding
circumferential slot 104 and further expanding upper and lower
slots 102, as shown in phantom in FIG. 5B. This provides a
relatively large opening 120 through which a catheter may be
inserted through stent segment 32 and into the side branch for
placing stents, performing angioplasty, or carrying out other
interventions.
[0137] FIGS. 6A-6B illustrate a second embodiment of a stent
segment 32 according to the invention. In FIG. 6A, a portion of
stent segment 32 is shown in a planar shape for clarity. Similar to
the embodiment of FIG. 5A, stent segment 32 comprises two parallel
rows 122A, 122B of I-shaped cells 124 formed into a cylindrical
shape around axial axis A. Cells 124 have upper and lower axial
slots 126 and a connecting circumferential slot 128. Upper and
lower slots 126 are bounded by upper axial struts 130, lower axial
struts 132, curved outer ends 134, and curved inner ends 136.
Circumferential slots 128 are bounded by outer circumferential
strut 138 and inner circumferential strut 140. Each I-shaped cell
124 is connected to the adjacent I-shaped cell 124 in the same row
122 by a circumferential connecting strut 142. Row 122A is
connected to row 122B by the merger or joining of curved inner ends
136 of at least one (and preferably three) of upper and lower slots
126 in each cell 124.
[0138] One of the differences between the embodiment of FIGS. 6A-6B
and that of FIGS. 5A-5B is the way in which spacing is maintained
between adjacent stent segments. In place of the spacing members
112 of the earlier embodiment, the embodiment of FIG. 6A includes a
bulge 144 in upper and lower axial struts 130, 132 extending
circumferentially outwardly from axial slots 126. These give axial
slots 126 an arrowhead or cross shape at their inner and outer
ends. The bulge 144 in each upper axial strut 130 extends toward
the bulge 144 in a lower axial strut 132 in the same cell 100 or in
an adjacent cell 100, thus creating a concave abutment 146 in the
space between each axial slot 126. Concave abutments 146 are
configured to receive and engage curved outer ends 134 of cells 124
in the adjacent stent segment, thereby maintaining spacing between
the stent segments. The axial location of bulges 144 along upper
and lower axial struts 130, 132 may be selected to provide the
desired degree of inter-segment spacing.
[0139] FIG. 6B shows two stent segments 32 of FIG. 6A in an
expanded condition. It may be seen that axial slots 124 are
deformed into a circumferentially widened modified diamond shape
with bulges 144 on the now diagonal upper and lower axial struts
130, 132. Circumferential slots 128 are generally the same size and
shape as in the unexpanded configuration. Bulges 144 have been
pulled away from each other to some extent, but still provide a
concave abutment 146 to maintain a minimum degree of spacing
between adjacent stent segments. As in the earlier embodiment, some
axial shortening of each segment occurs upon expansion and stent
geometry can be optimized to provide the ideal intersegment
spacing.
[0140] It should also be noted that the embodiment of FIGS. 6A-6B
retains the feature described above with respect to FIGS. 5A-5B to
enable access to vessel side branches blocked by stent segment 32.
Should such side branch access be desired, a dilatation catheter
may be inserted into circumferential slot 128 and expanded to
provide an enlarged opening through which a side branch may be
entered.
[0141] Referring now to FIGS. 7A-7E, the use of the stent delivery
catheter of the invention will be described. While the invention
will be described in the context of coronary artery treatment, it
should be understood that the invention is useful in any of a
variety of blood vessels and other body lumens in which stents are
deployed, including the carotid, femoral, iliac and other arteries,
as well as veins and other fluid-carrying vessels. A guiding
catheter (not shown) is first inserted into a peripheral artery
such as the femoral and advanced to the ostium of the target
coronary artery. A guidewire GW is then inserted through the
guiding catheter into the coronary artery A where lesion L is to be
treated. The proximal end of guidewire GW is then inserted through
nosecone 28 and guidewire tube 34 outside the patient's body and
stent delivery catheter 20 is slidably advanced over guidewire GW
and through the guiding catheter into the coronary artery A. Slider
assembly 50 is positioned within the hemostasis valve at the
proximal end of the guiding catheter, which is then tightened to
provide a hemostatic seal with the exterior of the slider body 52.
Stent delivery catheter 20 is positioned through a lesion L to be
treated such that nosecone 28 is distal to lesion L. During this
positioning, sheath 25 is positioned distally up to nosecone 28 so
as to surround expandable member 24 and all of the stent segments
32 thereon.
[0142] Optionally, lesion L may be pre-dilated prior to stent
deployment. Pre-dilation may be performed prior to introduction of
stent delivery catheter 20 by inserting an angioplasty catheter
over guidewire GW and dilating lesion L. Alternatively, stent
delivery catheter 20 may be used for pre-dilation by retracting
sheath 25 along with stent segments 32 to expose an extremity of
expandable member 24 long enough to extend through the entire
lesion. This may be done while delivery catheter 20 is positioned
proximally of lesion L or with expandable member 24 extending
through lesion L. Fluoroscopy enables the user to visualize the
extent of sheath retraction relative to lesion L by observing the
position of marker 56 on the garage 55 contained at the distal end
of the sheath 25 relative to the markers 82 formed on the guidewire
tube 34 beneath the expandable member 24. To allow stent segments
32 to move proximally relative to expandable member 24, force is
released from pusher tube 86 and valve member 58 engages and draws
the stent segments proximally with sheath 25. The pusher tube 86 is
retracted along with the outer sheath 25 by use of an actuator
provided on the handle 38. With the appropriate length of
expandable member 24 exposed, expandable member 24 is positioned
within lesion L and inflation fluid is introduced through inflation
lumen 66 to inflate expandable member 24 distally of sheath 25 and
thereby dilate lesion L. Expandable member 24 is then deflated and
retracted within sheath 25 while maintaining force on pusher tube
86 so that stent segments 32 are positioned up to the distal end of
expandable member 24, surrounded by sheath 25.
[0143] Following any predilatation, stent delivery catheter 20 is
repositioned in artery A so that nosecone 28 is distal to lesion L
as shown in FIG. 7A. Sheath 25 is then retracted as in FIG. 7B to
expose the appropriate number of stent segments 32 to cover lesion
L. Again, fluoroscopy can be used to visualize the position of
sheath 25 by observing marker 56 thereon relative to marker 82
within expandable member 24. As sheath 25 is drawn proximally,
force is maintained against pusher tube 86 so that stent segments
32 remain positioned up to the distal end of expandable member 24.
It should also be noted that sheath 25 moves proximally relative to
guidewire tube 34, which slides through guidewire tube exit port
35. Advantageously, regardless of the position of sheath 25,
guidewire tube 34 provides a smooth and continuous passage for
guidewire GW so that stent delivery catheter slides easily over
guidewire GW.
[0144] With the desired number of stent segments 32 exposed
distally of sheath 25, it is preferable to create some spacing
between the stent segments to be deployed and those remaining
enclosed within the sheath 25. This reduces the risk of dislodging
or partially expanding the distal-most stent segment 32 within
sheath 25 when expandable member 24 is inflated. Such spacing is
created, as shown in FIG. 7C, by releasing force against pusher
tube 86 and retracting both the pusher tube 86 and the sheath 25 a
short distance simultaneously. The engagement of valve member 58
with stent segments 32 moves those stent segments 32 within sheath
25 away from those stent segments 32 distal to sheath 25. The
length of this spacing is preferably equal to the length of about
1/2-1 stent segment, e.g., in one embodiment about 2-4 mm. By
observing radiopaque marker 56 on sheath 25, the operator can
adjust the spacing to be suitable in comparison to the length of
marker 56, which preferably has a length equal to the desired
spacing distance.
[0145] Expandable member 24 is then inflated by delivering
inflation fluid through inflation lumen 66, as shown in FIG. 7D.
The exposed distal portion of expandable member 24 expands so as to
expand stent segments 32 thereon into engagement with lesion L. If
predilatation was not performed, lesion L may be dilated during the
deployment of stent segments 32 by appropriate expansion of
expandable member 24. Sheath 25 constrains the expansion of the
proximal portion of expandable member 24 and those stent segments
32 within sheath 25.
[0146] Expandable member 24 is then deflated, leaving stent
segments 32 in a plastically-deformed, expanded configuration
within lesion L, as shown in FIG. 7E. The alternative embodiment of
stent segment 32 illustrated in FIGS. 6A-6B is shown in a similarly
expanded condition in FIG. 8. With stent segments 32 deployed,
expandable member 24 may be retracted within sheath 25, again
maintaining force against pusher tube 86 to slide stent segments 32
toward the distal end of expandable member 24. Expandable member 24
is moved proximally relative to stent segments 32 until the
distal-most stent segment engages stop 78 (FIGS. 2A-2B), thereby
placing stent segments 32 in position for deployment. Stent
delivery catheter 20 is then ready to be repositioned at a
different lesion in the same or different artery, and additional
stent segments may be deployed. During such repositioning,
guidewire tube 34 facilitates smooth tracking over guidewire GW.
Advantageously, multiple lesions of various lengths may be treated
in this way without removing stent delivery catheter 20 from the
patient's body. Should there be a need to exchange stent delivery
catheter 20 with other catheters to be introduced over guidewire
GW, guidewire tube 34 facilitates quick and easy exchanges.
[0147] It should be understood that when the movement of the pusher
tube, sheath, or stent segments is described in relation to other
components of the delivery catheter of the invention, such movement
is relative and will encompass both moving the sheath, pusher tube,
or stent segments while keeping the other component(s) stationary,
keeping the sheath, pusher tube or stent segments stationary while
moving the other component(s), or moving multiple components
simultaneously relative to each other.
[0148] While the foregoing description of the invention is directed
to a stent delivery catheter for deploying stents into vascular
lumens to maintain patency, it should be understood that various
other types of wire-guided catheters also may embody the principles
of the invention. For example, balloon catheters for angioplasty
and other purposes, particularly those having a slidable external
sheath surrounding the balloon, may be constructed in accordance
with the invention. Other types of catheters for deployment of
prosthetic devices such as embolic coils, stent grafts, aneurism
repair devices, annuloplasty rings, heart valves, anastomosis
devices, staples or clips, as well as ultrasound and angiography
catheters, electrophysiological mapping and ablation catheters, and
other devices may also utilize the principles of the invention.
[0149] Although the above is complete description of the preferred
embodiments of the invention, various alternatives, additions,
modifications and improvements may be made without departing from
the scope thereof, which is defined by the claims.
* * * * *