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Claims  |
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I claim:
1. A method for introducing a stent or a stent-graft which is diametrically
self-expanding and which is diametrically compressed by axial extension,
said method comprising:
a) providing first and second gripping members, each having a distal
gripping end, said first and second gripping members being axially
displaceable one relative to the other;
b) gripping the distal end of the stent or stent-graft between the gripping
distal ends of said first and second gripping members;
c) providing a sheath member having a proximal and a distal end;
d) inserting the gripped distal end of the stent or stent-graft into the
proximal end of the sheath member and advancing the distal end of the
stent or stent-graft until it is substantially completely covered by the
sheath member;
e) locating the sheath member, the covered stent or stent-graft, and the
first and second gripping members at a site for deploying the stent or
stent-graft;
f) moving one of the sheath member and the first and second gripping
members to effect a displacement of the sheath member in a proximal
direction relative to the first and second gripping members until the
stent or stent-graft is uncovered;
g) releasing the stent or stent-graft from the first and second gripping
members by axially displacing one of said first and second gripping
members relative to the other of said first and second gripping members;
and
h) withdrawing the first and second gripping members from the site for
deploying the stent or stent-graft.
2. A method according to claim 1, further comprising:
after said locating and prior to said moving one of the sheath member and
the first and second gripping members,
i) partially withdrawing the sheath member to uncover only a portion of the
stent or stent-graft; and
j) relocating the sheath member, the partially covered stent or
stent-graft, and the first and second gripping members at the site for
deploying the stent or stent-graft.
3. A method according to claim 2, further comprising:
after said moving one of the sheath member and the first and second
gripping members, and prior to said releasing,
k) distally relocating the stent or stent-graft, and the first and second
gripping members at the site for deploying the stent or stent-graft.
4. A method according to claim 1, further comprising:
after said gripping and prior to said inserting,
i) locking the first and second gripping members in the gripping position
to prevent the distal end of the stent or stent-graft from premature
release from the first and second gripping members.
5. A method according to claim 1, further comprising:
prior to said locating,
i) providing at least one of the first and second gripping members with an
axial throughbore;
j) providing a guide wire extending from the site for deploying the stent
or stent-graft; and
k) sliding the first and second gripping members over the guide wire with
the guide wire extending through the axial throughbore,
wherein
said locating is accomplished by guiding the first and second gripping
members along the guide wire.
6. An apparatus for introducing a stent or a stent-graft which is
diametrically self-expanding and which is diametrically compressed by
axial extension, said apparatus comprising:
a) a hollow tube having a proximal end and a distal end;
b) a control member having a proximal end and a distal end and extending
through said hollow tube;
d) an end cap coupled to said distal end of said control member;
e) a sheath member movable relative to said end cap and having a an inner
diameter larger than an outer diameter of said hollow tube and smaller
than an outer diameter of the stent or stent-graft when the stent or
stent-graft is placed in an expanded position, wherein said sheath member
extends over at least a portion of said hollow tube, said control member,
and the stent or stent-graft when the stent or stent-graft is placed in a
contracted position, and movement of one of said sheath member and said
end cap relative to the other permits the stent or stent-graft to expand,
wherein movement of one of said proximal end of said hollow tube and said
proximal end of said control member relative to the other effects an axial
displacement of one of said hollow tube and said control member relative
to the other from a first position where said end cap covers said distal
end of said hollow tube to a second position where said end cap is axially
spaced from and uncovers said distal end of said hollow tube.
7. An apparatus according to claim 6, further comprising:
f) an actuation means coupled to said proximal ends of said hollow tube and
said control member for effecting an axial displacement of one of said
hollow tube and said control member relative to the other from said first
position where said end cap covers said distal end of said hollow tube to
said second position where said end cap is axially spaced from and
uncovers said distal end of said hollow tube, wherein
the distal end of the stent or stent-graft is capturable between said
distal end of said hollow tube and said end cap by appropriate
manipulation of said actuation means to cause said end cap and hollow tube
to assume said first position, and is releasable from between said distal
end of said hollow tube and said end cap by appropriate manipulation of
said actuation means to cause said end cap and hollow tube to assume said
second position.
8. An apparatus according to claim 7, wherein:
said actuation means includes a lever member pivotally connected to a
handle member, said handle member being coupled to said proximal end of
said hollow tube, and said lever member being coupled to said proximal end
of said control member.
9. An apparatus according to claim 7, wherein:
said actuation means includes a finger grip means coupled to one of said
proximal end of said hollow tube and said proximal end of said control
member, and a handle coupled to the other of said proximal end of said
hollow tube and said proximal end of said control member.
10. An apparatus according to claim 9, wherein:
said finger grip comprises a spool and said handle comprises a slotted
shaft,
said control member is coupled to said slotted shaft, and
said hollow tube is coupled to said spool.
11. An apparatus according to claim 10, wherein:
said end cap and said control member are provided with axial throughbores
for receiving a guide wire, and
said slotted handle is provided with a proximal throughbore which
communicates with the throughbore in said control member.
12. An apparatus according to claim 11, wherein:
said proximal throughbore is at least partially defined by a luer coupling.
13. An apparatus according to claim 7, wherein:
said actuation means comprises a ratchet member coupled to one of said
proximal end of said hollow tube and said proximal end of said control
member and a handle coupled to the other of said proximal end of said
hollow tube and said proximal end of said control member, said handle
having a lever member for engaging said ratchet member.
14. An apparatus according to claim 7, wherein:
said actuation means includes locking means for locking said hollow tube
and said end cap in said first position.
15. An apparatus according to claim 14, wherein:
said locking means is selected from the group consisting of a hook and
eyelet, a set screw, and a latch.
16. An apparatus according to claim 6, wherein:
said hollow tube is a flexible coil having an outer surface covered with a
thin flexible covering.
17. An apparatus according to claim 6, wherein:
said control member is a flexible member covered with a braided covering to
inhibit axial stretching.
18. An apparatus according to claim 6, wherein:
said end cap and said control member are provided with axial throughbores
for receiving a guide wire.
19. An apparatus according to claim 6, wherein:
said end cap has a concave portion which covers said distal end of said
hollow tube when said end cap and said distal end of said hollow tube are
in said first position.
20. An apparatus according to claim 6, wherein:
said sheath member is provided with a proximal gripping flange.
21. An apparatus according to claim 6, wherein:
said sheath member is provided with a proximal hemostasis valve means.
22. An apparatus for introducing a stent or a stent-graft which is
diametrically self-expanding and which is diametrically compressed by
axial extension, said apparatus comprising:
a) a hollow tube having a proximal end, and a distal end having a
substantially frustroconical cover;
b) a control member having a proximal end and a distal end and extending
through said hollow tube;
d) an end cap coupled to said distal end of said control member;
e) an actuation means coupled to said proximal ends end of said hollow tube
and said control member for effecting axial displacement of one of said
hollow tube and said control member relative to the other from a first
position where said end cap covers said distal end of said hollow tube to
a second position where said end cap is axially spaced from and uncovers
said distal end of said hollow tube, wherein
the distal end of the stent or stent-graft is capturable between said
distal end of said hollow tube and said end cap by appropriate
manipulation of said actuation means to cause said end cap and hollow tube
to assume said first position, and is releasable from between said distal
end of said hollow tube and said end cap by appropriate manipulation of
said actuation means to cause said end cap and hollow tube to assume said
second position.
23. An apparatus according to claim 22, wherein:
said end cap has a substantially frustroconical interior surface.
24. An apparatus according to claim 23, wherein:
said end cap and said control member are provided with axial throughbores
for receiving a guide wire.
25. An apparatus according to claim 24, wherein:
said end cap is provided with a distally extending soft catheter tip. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to the delivery and deployment of a
transluminal prosthesis. More particularly, this invention relates to a
method and apparatus for delivering and deploying a flexible tubular
prosthesis having a diameter which is variable by axial movement of the
ends of the prosthesis.
2. State of the Art
Transluminal prostheses are well known in the medical arts for implantation
in blood vessels, biliary ducts, or other similar organs of the living
body. These prostheses are commonly known as stents and are used to
maintain, open, or dilate tubular strictures or to support tubular
structures that are being anastomosed. When bio-compatible materials are
used as a covering or lining for the stent, the prosthesis is called a
stent-graft or endoluminal graft. A typical state of the art stent such as
disclosed in U.S. Pat. No. 4,655,771 to Wallsten or in U.K. Patent Number
1,205,743 to Didcott is shown herein in prior art FIGS. 1, 1a, 2, and 2a.
Didcott and Wallsten disclose a tubular body stent 10 composed of wire
elements 12, each of which extends in a helical configuration with the
centerline 14 of the stent 10 as a common axis. Half of the elements 12
are wound in one direction while the other half are wound in an opposite
direction. With this configuration, the diameter of the stent is
changeable by axial movement of the ends 9, 11 of the stent. Typically,
the crossing elements form a braid-like configuration and are arranged so
that the diameter of the stent 10 is normally expanded as shown in FIGS. 1
and 1a. The diameter may be contracted by pulling the ends 9, 11 of the
stent 10 away from each other as shown by the arrows 16, 18 in FIG. 2.
When the ends of the body are released, the diameter of the stent 10
self-expands and draws the ends 9, 11 of the stent closer to each other.
A stent such as the ones described by Didcott and Wallsten may be
introduced into the body by stretching it until its diameter is reduced
sufficiently so that it can be fed into a catheter. The stent is delivered
through the catheter to the site of deployment and then released from the
catheter whereupon it self-expands. A simple delivery device for locating
and deploying the stent is shown in prior art FIG. 3 and includes a
flexible catheter 20 having a proximal handle 21 and a flexible plunger 22
having a proximal handle 23. As shown in FIG. 3, the stent 10 is partially
inserted into the distal end of the catheter 20 and partially expanded
around the inner wall of an artery 24. Those skilled in the art will
appreciate that prior to delivery and deployment, the stent is completely
inserted into the distal end of the catheter 20 and the distal end of the
catheter is positioned at the site of deployment, such as artery 24. The
handles 21, 23 of the catheter 20 and the plunger 22 are moved relative to
each other as shown by the arrows 25, 27 thereby moving the catheter and
plunger relative to each other and pushing the stent 10 out of the distal
end of the catheter. It will be appreciated, however, that this prior art
delivery device is deficient in several respects. First, pushing the stent
10 with the plunger 22 can damage the wires comprising the stent. In
particular, the wires can kink or bunch up preventing proper deployment of
the stent. The ends of the wires can bend inward occluding the lumen of
the stent. Furthermore, the wires can break and cause the stent to
partially come apart. Second, by releasing the distal end of the stent
first, the stent can no longer be positioned in the distal direction. In
particular, the ends of the wires of the distal end of the stent will
typically lodge themselves in the wall of the artery 24 and prohibit
movement of the stent in the distal direction. Third, as the stent is
released from the catheter, it contracts in length as it expands
diametrically. Therefore, care must be taken to position the distal end of
the catheter further into the artery than the stent is to be deployed so
that when the stent is released, its length will contract to the location
where it is to be deployed. This substantially complicates proper location
of the stent. Fourth, this prior art delivery device is difficult to load.
The stent must be manually stretched and carefully fed into the catheter
without bending the ends of its wires or allowing the ends of the wires to
penetrate the wall of the catheter. Fifth, when a coated stent is deployed
from its distal end first, retrograde to blood flow, for example if it is
maneuvered from the femoral artery to the aorta, the distal end of the
stent opens first, thereby being subjected to the full force of flowing
blood. This blood flow can cause the stent to compress prior to lodging in
the vessel wall, thus further complicating the accuracy of the deployment.
Another known device for delivering and deploying a stent is shown in prior
art FIG. 4. The prior art stretching device 30 of FIG. 4 has an inner
flexible tube 32 and an outer flexible tube 34 which are coupled at their
proximal ends to an actuation means (not shown) for producing relative
axial movement of the tubes. The inner tube 32 is provided with a pointed
gripping device 36 at its distal end, and the outer tube 34 is provided
with a similar gripping device 38 at its distal end. Both gripping devices
36, 38 are operated by respective control wires 37, 39 which extend to the
proximal actuation means (not shown). The broken view of prior art FIG. 4
shows the stent 10 in a dotted line prior to axial stretching. Those
skilled in the art will appreciate that the ends of the stent 10 are
attached by the gripping means 36, 38 to the distal ends of the inner and
outer tubes 32, 34 and the tubes are axially moved to stretch the stent 10
to the size shown in solid lines in FIG. 4. The tubes carrying the
stretched stent are delivered to the site of deployment and moved relative
to each other to expand the stent. The gripping means 36, 38 are then
released and the stent expands diametrically while contracting axially.
This device allows for reasonably precise location of the stent since the
stent can be partially expanded diametrically at its center by movement of
the tubes before releasing the gripping means. However, the prior art
delivery device of FIG. 4 has a very complex and expensive construction.
It is also difficult to manipulate and the pointed gripping means can
damage the ends of the stent. In addition, with the delivery device of
FIG. 4, the stent-graft which is being delivered is exposed to blood
during its insertion, and this can result in a thromboembolism.
Furthermore, the numerous wires required to maintain the stent-graft in
its compressed state increases the profile of the stent-graft. In order to
maintain the stent-graft in its compressed state, the inner members must
be under extreme compression, thereby rendering the device stiff and
difficult to maneuver.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a method for
introducing a stent and a stent delivery system Which will not damage the
stent.
It is also an object of the invention to provide a stent introducing
apparatus which is easy to use.
It is another object of the invention to provide a stent introducing
apparatus which is simple to manufacture.
It is still another object of the invention to provide a method and
apparatus for introducing a stent which allows for precise location of the
stent.
It is yet another object of the invention to provide a stent introducer
which is easily bendable and can track a guide wire.
It is also an object of the invention to provide a stent introducer which
will open from its downstream end first.
It is still another object of the invention to provide a stent introducer
which has a soft tip.
In accord with these objects which will be discussed in detail below, the
stent delivery and deployment apparatus of the present invention includes
an introducer which is removably insertable through a hollow body such as
a blood vessel, a sinus tract, an esophagus, a trachea, a bile duct, an
anus, an intestine, or the like. The introducer includes three concentric
tubes: a hollow tube having a proximal end and a distal end; an inner
tubular actuation member having a proximal end and a distal end; and an
outer sheath. A cup-like gripping member is rigidly attached to the distal
end of the tubular actuation member. The proximal ends of the hollow tube
and the actuation member are coupled to an actuation device which effects
relative movement of the hollow tube and the actuation member. In this
manner, the cup-like gripping member moves relative to the distal end of
the hollow tube, thereby forming a clamping or gripping mechanism between
the cup-like member and the distal end of the hollow tube.
According to the method of the invention, the distal end of a stent or
stent-graft is inserted into the cup-like member and the actuation device
is manipulated to move the cup-like member and the distal end of the
hollow tube together, thereby gripping the distal end of the stent. The
distal end of the introducer is inserted into the sheath and pulls the
distal end of the stent into the sheath, thereby stretching and radially
compressing it to its reduced diameter. The sheath containing the stent
and the remainder of the introducer is maneuvered to the site for
deployment of the stent. The introducer is held in a stationary position
and the sheath is pulled partially back towards the proximal end of the
introducer so that a middle portion of the stent is released from the
sheath. The introducer, stent, and sheath can then be moved as one so that
the stent is precisely located before it is deployed. When the stent is in
a precise desired location, the introducer is held in a stationary
position and the sheath is pulled back further to release the proximal end
of the stent. The actuation device is then manipulated to release the
distal end of the stent from the cup-like cap member and the distal end of
the hollow tube. After this, the introducer is free to be removed through
the lumen of the diametrically expanded stent.
Preferred aspects of the apparatus of the invention include: providing a
latching or ratchet means on the actuation device so that the introducer
can be locked in the stent gripping position until the stent is at the
deployment site; providing the distal end of the hollow tube of the
introducer with a frustroconical tip; and providing a cup-like cap with a
mating frustroconical interior which matingly receives the frustroconical
tip of the hollow tube of the introducer.
According to another embodiment of the invention, the cup-like cap and the
control member are provided with an inner bore through which a guide wire
may be inserted and used to guide the apparatus to the site of stent
deployment. Other optional features of the apparatus include: controlling
the sheath with one or more wires; making the distal end of the cup-like
cap soft to reduce patient trauma; including radiopaque markers on the
introducer so that it can be seen under fluoroscopy; and providing
slippery surfaces on the sheath and the introducer to facilitate release
of the stent. The apparatus may be disposable or reusable and may be
dimensioned to suit particular applications.
Additional objects and advantages of the invention will become apparent to
those skilled in the art upon reference to the detailed description taken
in conjunction with the provided figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a broken side elevation view of a prior art stent expanded in a
non-stressed position;
FIG. 1a is a cross sectional view along line 1A--1A of FIG. 1;
FIG. 2 is a broken side elevation view of a prior art stent stretched and
contracted;
FIG. 2ais a cross sectional view along line 2A--2A of FIG. 2;
FIG. 3 is a broken cross sectional view of a first prior art stent delivery
and deployment apparatus;
FIG. 4 is a broken cross sectional view of the distal end of a second prior
art stent delivery and deployment apparatus;
FIG. 5 is a broken side elevation view in partial section of a first
embodiment of a stent introducer according to the invention;
FIG. 5a is a broken cross sectional view of a sheath for use with the stent
introducer according to the invention;
FIG. 6 is a broken cross sectional view of a second embodiment of a stent
introducer according to the invention;
FIG. 7 is a broken cross sectional view of a third embodiment of a stent
introducer according to the invention;
FIG. 7a is an enlarged broken cross sectional view of a portion of FIG. 7;
FIG. 8 is a broken cross sectional view of the distal end of a fourth
embodiment of a stent introducer according to the invention together with
a sheath;
FIG. 8a is an enlarged broken cross sectional view of the distal portion of
the stent introducer of FIG. 8;
FIG. 8b is an enlarged broken side elevation view of the proximal portion
of the stent introducer of FIG. 8;
FIGS. 9 and 9a are views similar to FIG. 8a showing the attachment of the
distal end of a stent to the introducer;
FIGS. 10 and 10a are views similar to FIG. 9 showing the insertion of the
introducer into the sheath; and
FIGS. 11, 11a, and 11b are views similar to FIG. 10 showing the deployment
of the stent by withdrawal of the sheath and releasing it from the distal
end of the introducer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIGS. 5 and 5a, a first embodiment of the stent delivery
apparatus of the invention includes a stent introducer 40 and a sheath 70.
The stent introducer 40 according to the invention includes a hollow tube
42 having a proximal end 44 and a distal end 46. A control member 48,
which may take the form of a rod, has a proximal end 50 and a distal end
52. The control member 48 extends through the hollow tube 42 and is
coupled at its distal end 52 to the interior of a cup-like cap 54. A lever
actuator 56 has a first handle member of finger grip means 58 and a second
handle or lever member or finger grip means 60 which are pivotally coupled
to each other by a pivot pin 62. An upper end 59of the first handle member
58 is coupled to the proximal end 44 of the hollow tube 42. An upper end
61 the lever member 60 is coupled to the proximal end 50 of the control
member 48. From the foregoing, those skilled in the art will appreciate
that when the handle member 58 and lever 60 are squeezed together, the
control member 48 is moved proximally through the hollow tube 42 and the
end cap 54 is brought into a position where it covers and engages the
distal end 46 of the hollow tube 42. Depending on the particular
application, the hollow tube and the control member may be made rigid or
flexible. Suitable materials for the tube and the control member include
polyethylene, polyurethane, NYLON, TEFLON, metal springs, coils or braids,
metal tubing, reinforced plastics, or combinations of these. If the
introducer is to be made rigid, the tube and control member may be made of
stainless steel, nitinol or the like.
As will be described in detail below with reference to FIGS. 9 and 9a,
according to the method of the invention, the distal end of a stent is
captured and held between the end cap 54 and the distal end 46 of the
hollow tube 42 when the handle and lever members are squeezed together as
described above. In order to hold the end cap against the distal end of
the tube, the handle and,lever members are preferably provided with
locking means such as a hook 57 and eyelet 63. With the distal end of a
stent captured and held between the end cap 54 and the distal end 46 of
the hollow tube 42, the introducer 40 is inserted into the proximal end 72
of a sheath 70 (FIG. 5a) until the end cap 54 extends just beyond the
distal end 74 of the sheath. The sheath, which is preferably made of 75D
polyurethane, NYLON, PET, PFE, PTFE, polyethylene, or the like, is
provided with a proximal gripping flange 76 to aid in this operation as
described in further detail below with reference to FIGS. 10 and 10a.
Moreover, the proximal end 72 of the sheath 70 may be provided with a
valve means (not shown) to prevent blood from leaking out of the sheath.
Turning now to FIG. 6, a second embodiment of the stent introducer 140 has
a similar hollow tube 42 with a proximal end 44 and a distal end 46. In
this embodiment, the end cap 154 is provided with a central bore 155, and
the control member 148 is similarly provided with a central bore 149 which
extends from its proximal end 150 to its distal end 152. The actuator
handle or finger grip means 156 includes an inverted L-shaped member 160
which is coupled to the proximal end 44 of the hollow tube 42, and a
sliding member or finger grip means 158 which is coupled to the proximal
end 150 of the control member 148. Those skilled in the art will
appreciate that when the actuator members 158, 160 are squeezed together,
the end cap 154 covers and engages the distal end 46 of the tube 42. A
latch 163 is provided on the lower portion of the inverted L-shaped member
160 for holding the actuator handle members together as described above
with reference to the first embodiment. Both members 158 and 160 are
provided with bores 159, 161, respectively, through which a guide wire 53
may be inserted. Guide wire 53 extends through the central bore 149 of the
control member 148 and the central bore 155 of the end cap 154 to the
deployment site (not shown) and helps to guide the introducer 140 to the
deployment site.
FIG. 7 shows another embodiment of an introducer 240 according to the
invention. The introducer 240 includes a flexible coil 242 which is
coupled at its proximal end 244 to a pistol grip 260. The distal end 246
of coil, 242 is provided with a tapered capturing or locking member or
cover 247 having a substantially frustroconical distal end. A flexible
control member 248 extends through the coil 242. The control member 248
has a cylinder 258 coupled to its proximal end 250 and an end cap 154
coupled to its distal end 252. The cylinder 258 is provided with a
serrated surface or rack 259 along a proximal portion thereof and is
mounted in a throughbore 262 in the pistol grip or finger grip means 260.
A proximal handle portion 264 is mounted on the proximal end of the
cylinder 258 and is accessible outside the pistol grip as seen in FIG. 7.
The pistol grip 260 is provided with a reversible pawl 261 and a ratchet
trigger or finger grip means 263 which is biased by a return spring 263a.
Those skilled in the art will appreciate that when the reversible pawl 261
is set in a first position, the cylinder 258 may be advanced in the
proximal direction relative to the pistol grip 260 by pulling on the
handle portion 264 so that the end cap 154 is brought into engagement with
and covers the tapered locking member 247. The pawl 261 may also be set in
a second position such that movement of the trigger 263 causes the end cap
154 to move away from the tapered locking member 247. The control member
248 is provided with a longitudinal throughbore 249 which communicates
with a central throughbore 155 in the end cap 154 and a throughbore 265 in
the cylinder 258. A guide wire (not shown) may be inserted through the
central bore 155, the longitudinal bore 249 and the throughbore 265 in
order to aid in guiding the introducer 240 to the site of deployment.
FIG. 7a shows an enlarged cross section of a portion of the coil 242 and
the control member 248. The control member 248 is preferably a
catheter-like structure with a reinforced braid 248a to limit axial
stretching. The coil 242 may also have a thin flexible coating 242a on its
outer surface to prevent blood leakage through the coil.
FIGS. 8, 8a and 8b show a presently preferred embodiment of the stent
introducer 340 according to the invention. The introducer 340 includes a
flexible coil 342 and a coaxial control member 348 which extends through
the coil 342. The proximal ends of the coil and control member are coupled
to a slotted handle 358 such as the type used in endoscopic biopsy
forceps. The distal end 346 of coil 342 is provided with a tapered
capturing or locking member 347 having a substantially frustroconical
distal end.
As shown in FIG. 8, a preferred sheath 170 is provided with a central
throughbore 174 and a proximal collar 178 carrying a sheath fastener hub
176. The hub 176 is provided with internal threads and an O-ring washer
(not shown). The proximal collar 178 is provided with external threads 177
which engage the internal threads of the hub 176. The hub is tightened
against the collar by rotational engagement of their respective threads.
When the hub is thus tightened the O-ring forms a hemostasis valve between
the sheath and the introducer to prevent blood leakage out the proximal
end of the sheath.
FIG. 8a shows the distal portion of a presently preferred embodiment of the
stent introducer according to the invention. This embodiment is similar to
the embodiment described above with a flexible coil 342 having a
frustroconical tapered capturing or locking member 347 at its distal end
346. The control member 348 is preferably made from stiff-plastic such as
polyurethane having a Shore 75D hardness or a steel braid reinforced
polyurethane tube. The distal end 352 of the control member 348 is
provided with a rigid cap 354 which has a proximal cylindrical portion
353, an interior frustroconical portion 353a, an Outer frustroconical
portion 356, and a distally extending soft catheter tip 357. The soft
catheter tip 357 is preferably provided with a tapered distal end 351 and
an internal throughbore 355 which communicates with a longitudinal bore
349 in the control member 348. Bores 355 and 349 are provided for
insertion of a guide wire as well as for the injection of radiopaque dyes
as described in more detail below. It will be appreciated that this
embodiment of the distal portion of the stent introducer can be used with
any one of the actuation handles described above with reference to FIGS.
5-8.
As shown in FIG. 8b, the slotted handle 358 is provided with a shaft 359
having a central slot 360 which communicates with a distal throughbore 362
and a proximal throughbore 364. The proximal throughbore 364 preferably
terminates in a proximal luer coupling 366 and a hand grip or finger grip
means 368 is provided on a proximal portion of the shaft 359 between the
slot 360 and the luer coupling 366. A displaceable spool or finger grip
means 370 having a central throughbore 372 is slideably disposed on the
shaft 359. The spool 370 is also preferably provided with a locking set
screw 374 for locking its position on the shaft 359.
The proximal end of the control member 348 is coupled to the handle 358
preferably by bonding it to the proximal throughbore 364 so that the bore
349 in the control member 348 is in communication with the luer coupling
366. The proximal end 344 of the coil 342 is coupled to the spool 370 by
means of a cross block 376. The coil passes freely through the distal bore
362 in the shaft 359. From the foregoing, it will be understood that
movement of the spool 370 relative to the shaft 359 effects a movement of
the coil 342 relative to the control member 348, and thereby effects
movement of the locking member 347 relative to the cap 354. A guide wire
(not shown) may be inserted through the central bore 355, the longitudinal
bore 349 and the luer coupling 366 in order to aid in guiding the
introducer 340 to the site of deployment. A source of radiopaque fluid may
be coupled to the luer 366 for injection at the deployment site. A
hemostasis value may also be connected to luer 366 to prevent blood from
leaking between the guidewire and the control member.
The method of the invention is best understood with reference to FIGS. 9,
9a, 10, 10a, 11, 11a, and 11b. As seen in FIGS. 9, 9a, 10, and 10a, the
stent introducer 340 according to the invention is operated by the moving
the cap 354 away from the frustroconical tapered locking member 347 as
described above with reference to FIGS. 5-7. The distal end 11 of a stent
10 is diametrically compressed and inserted into the cylindrical portion
353 of the cap 354 as shown in FIG. 9. The diametric compression of the
distal end of the stent can be facilitated by looping a suture around the
distal end of the stent or by using a funnel to insert the distal end of
the stent into the cap 354. The cap 354 is then brought into engagement
with the frustroconical tapered locking member 347 as described above,
thus capturing the distal end 11 of the stent 10. The introducer can be
"locked" in this position by use of the locking device 57, 63, 163, 261,
263 or 374 shown and described above with reference to FIGS. 5-8. The
distally extending soft catheter tip 357 of the cap 354 is then inserted
into the proximal end 72 of a sheath 70 as Shown in FIG. 10. Those skilled
in the art will appreciate that as the introducer 340 is inserted into the
sheath 70, the outer diameter of the stent 10 is compressed and the length
of the stent 10 is extended. While gripping the sheath 70 with the
gripping flange 76, the introducer 340 is advanced proximally until the
entire stent 10 is enclosed within the sheath 70 and the distally
extending soft catheter tip 357 of the cap 354 extends somewhat from the
distal end 74 of the sheath 70 as shown in FIG. 10a. When the stent 10,
sheath 70, and introducer 340 are assembled in the configuration shown in
FIG. 10a, the entire assembly is ready for delivery to the stent
deployment site. Guiding the assembly to the stent deployment site may be
facilitated through the use of a guide wire as described above. Those
skilled in the art will appreciate that a clamping device, such as
clamping device 176 in FIG. 8, can be provided on the sheath to clamp it
to the introducer and prevent inadvertent movement of the sheath relative
to the introducer while the assembly is guided to the deployment site.
Generally, however, there is a snug fit between the introducer, stent, and
sheath, and therefore, clamping is not necessary.
The stent 10 is deployed at the deployment site (not shown) in a sequence
of operations described with reference to FIGS. 11, 11a, and 11b. When the
introducer 340, stent 10, and sheath 70 are positioned at the deployment
site, according to a preferred embodiment, the introducer 340 is held
stationary while the sheath 70 is partially withdrawn in a proximal
direction as shown in FIG. 11, thereby allowing partial diametric
expansion of the stent 10. In this position, the distal end 11 of the
stent 10 remains captured between the cap 354 and the tapered locking
member 347 and the proximal end 9 of the stent 10 remains covered by the
sheath 70. The stent is therefore movable proximally and distally by
moving the sheath 70 and the introducer 340 together since the wire ends
of the stent are prevented from lodging into the organ wall at the
deployment site. When the stent 10 is precisely located, its proximal end
9 is released by further withdrawal of the sheath 70 as shown in FIG. 11a.
The release of the proximal end 9 of the stent 10 prevents the stent from
being moved proximally. However, so long as the distal end 11 of the stent
10 remains captured by the cap 354 and the tapered locking member 347, the
stent can be relocated in the distal direction. The stent 10 is fully
deployed when the distal end 11 of the | | |
