Note: Descriptions are shown in the official language in which they were submitted.
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STENT DEPLOYMENT CATHETER WITIrI COLLAPSIBLE SHEATH
Field of the Invention
This invention relates to a stent delivery catheter system, such as the
kind used in percutaneous transluminal coronary angioplasty (PTCA) procedures.
More particularly, it relates to a stent delivery catheter employing a
collapsible sheath
which collapses during the retraction of a distal sheath during the release of
a self-
expanding or balloon expandable stent.
Background of the Invention
In typical PTCA procedures, a guiding catheter is percutaneously
introduced into the vascular system of a patient and advanced through the
aorta until
the distal end is in the ostium of the desired coronary artery. Using
fluoroscopy, a
guide wire is then advanced through the guiding catheter and across the site
to be
treated in the coronary artery. An over the wire (OTW) balloon catheter is
advanced
over the guide wire to the treatment site. The balloon is then expanded to
reopen the
artery. The OTW catheter may have a guide wire lumen whicli is as long as the
catheter or it may be a rapid exchange catheter wherein the guide wire lumen
is
substantially shorter than the catheter. Alternatively, a fixed wire balloon
catheter
could be used. This device features a guide wire which is affixed to the
catheter and
cannot be removed.
To help prevent arterial closure, repair dissection, or prevent
restenosis, a physician can implant an intravascular prosthesis, or a stent,
for
maintaining vascular patency inside the artery at the lesion. The stent may
either be a
self-expanding stent or a balloon expandable stent. For the latter type, the
stent is
often delivered on a balloon and the balloon is used to the exvand the stent.
The self-
expanding stents may be made of shape memory materials sucll as NITINOL or
constructed of regular metals but of a design which exhibits self expansion
characteristics.
In certain known stent delivery catheters, a stent and an optional
balloon are positioned at the distal end of the catheter, around a core lumen.
The
stent and balloon are held down and covered by a sheath or sleeve. When the
distal
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portion is in its desired location of the targeted vessel the sheath or sleeve
is retracted
to expose the stent. After the sheath is removed, the stent is free to self-
expand or be
expanded with a balloon.
In a coronary stent deployment system which utilizes a retractable
sheath one problem which is encountered is the interaction of the sheath and
guide
catheter upon retraction. The traditional way of dealing with this is to make
the
retractable sheath long enough so that it will be contained in the guide
catheter at all
times. This increases system profile, reduces flexibility and creates excess
friction
upon sheath retraction. The invention disclosed reduces the sheath length,
maintains a
reduced system profile and provides good flexibility.
Summary of the Invention
The present invention provides an improved stent delivery system. The
stent delivery system comprises a catheter having a proximal outer, a stent
receiving
portion adapted to receive a stent near the distal end of the catheter, a
retractable distal
sheath concentrically arranged around the stent receiving portion and a pull
back
means connected to the distal sheath. The catheter further comprises a
collapsible
sheath located between and adhered to the proximal outer and the retractable
distal
sheath. During retraction of the distal sheath the collapsible sheath
collapses upon
itself, or accordions upon its preformed pleats or creases, providing room for
the
distal sheath to retract unencumbered, thereby freeing the loaded stent. The
inclusion
of the collapsible sheath significantly reduces the required sheath length,
maintains a
reduced system profile, provides good flexibility and provides a protective
covering to
the wire pull back mechanism.
Other objects, features, embodiments and characteristics of the present
invention, as well as the methods of operation and functions of the related
elements of
the structure, and the combination of parts and economics of manufacture, will
become more apparent upon consideration of the following description with
reference
to the accompanying drawings, all of which form a part of this specification.
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Brief Description of the Figures
Figure 1 shows a side view of a catheter according to the invention
having a loaded stent including a cross-sectional view of the distal portion
thereof and
a side view of the proximal end of a catheter according to the invention
showing the
manifold portion thereof.
Figure 2 shows a side view of a catheter according to the invention
having a loaded self-expanding stent including a cross-sectional view of the
distal
portion thereof, wherein the loaded stent is shown as partially deployed, and
a side
view of the proximal end of a catheter according to the invention showing the
manifold portion thereof.
Figure 3 shows a side view of a catheter according to the invention
having a loaded stent including a cross-sectional view of the distal portion
thereof,
wherein the loaded stent is shown as fully deployed and a side view of the
proximai
end of a catheter according to the invention showing the m.anifold portion
thereof.
Figure 4 shows a side view of a catheter according to an alternative
embodiment of the invention having a loaded stent including a cross-sectional
view of
the distal portion thereof.
Figure 5 shows a side view of a catheter according to an alternative
embodiment of the invention having a loaded stent including a cross-sectional
view of
the distal portion thereof, wherein the loaded stent is shown as fully
deployed.
Figure 6 shows a side view of a catheter according to an alternative
embodiment of the invention having a loaded stent including a cross-sectional
view of
the distal portion thereof.
,25 Figure 7 is a sectional view of the catheter thereof, taken along line 7-7
in Figure 6.
. Figure 8 shows a side view of a catheter according to an alternative
embodiment of the invention having a loaded stent including a cross-sectional
view of
the distal portion thereof.
Figure 9 shows a side view of a catheter according to an alternative
embodiment of the invention having a loaded stent including a cross-sectional
view of
the distal portion thereof.
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Figure 9a shows a partial exploded view of Fig. 9.
Figure 9b shows a partial exploded view of Fig. 9.
Figure 9c shows a partial exploded view of Fig. 9.
Detailed Description of the Invention
Figure 1 shows a cross-section of the distal portion of a specific
embodiment of the stent delivery catheter, generally designated as 5, that is
the
subject of the present invention. The device generally comprises a proximal
outer 10
which covers the majority of the catheter 5 excluding a portion of the distal
end of the
catheter 5. This outer 10 is characterized by a flexible tube which contains a
pull wire
lumen and a guide wire lumen. Preferably the outer 10 is comprised of a high
density
polyethylene (HDPE), SURLYN, a combination of HDPE and low density
polyethylene (LDPE) or NYLON material. The proximal outer 10 encloses an
optional guide wire lumen 15 which extends through and terminates with the
distal tip
25 of the catheter 5. Preferably the guide wire lumen 15 encloses a guide wire
20
which aids in the navigation of the catheter 5 through the appropriate vessel.
The
guide wire lumen 15 is made of flexible, but incompressible construction such
as a
polymer encapsulated braid or coil. The flexibility of the braid/coil allows
the catheter
5 to navigate through body lumens and the incompressibility of the braid/coil
aids in
maintaining the integrity of the catheter and aids in deployment accuracy when
the
sheath is being retracted during stent release. The braid/coil may be
comprised of
stainless steel or NITINOL, but preferably stainless steel encased in a
polymer such as
a polyimide, HDPE, TEFLON or urethane, but preferably polyimide and TEFLON.
Situated just proximal to the distal tip 25 is the portion 30 of catheter 5
around which the stent is concentrically carried. The stent 35 surrounds the
guide wire lumen 15. The stent 35 is preferably a NitinolTM. or mesh self-
expanding stent, but
may also be a balloon expandable stent carried by an expansion balloon.
Self-expanding and balloon expandable stents are well known in the art and
require
no further instruction.
The present invention further comprises a retractable distal sheath 40
which covers and contains the loaded stent 35. The retractable distal sheath
40 will
hold a self-expanding stent in its reduced delivery configuration. The
retractable
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distal sheath will merely contain a balloon expandable stent which was
positioned over
an expansion balloon. The distal sheath 40 is connected to a retracting member
45, or
pull wire, which allows a physician to retract the distal sheath 40 from the
proximal
end of the catheter 5, tlius releasing the stent 35 in the targeted area of
the vessel. The
retractable sheath 40 may be flexible or rigid, and is generally used to
retain the stent
35 and protect the vessel wall during delivery. The distal sheath is
preferably formed
of a material which provides tensile strength, but is flexible, such as a
braid, coil, a
super elastic allov, polymer, stainless steel or other similar composites. The
retracting
member 45 may be a rod, a cable, a tube which may also be used to transport
fluids, a
pull back wire, -gtiide wire or the like, but is preferably a wire. In
addition, the
retracting member 45 may be tapered along its length to impart varying
flexibility.
Those skilled in the art will recognize other suitable materials and
constructions may
be employed to serve substantially the same function. The figures show two
pull
wires, but one is preferred. It should be understood that any desired number
of pull
wires could be utilized. The retracting member 45 extends longitudinally
within the
proximal outer 10, optionally through a retracting member lumen (not shown),
such as
a HDPE, nylon or polyether block amide (PEBAX) tube. In one embodiment, the
retracting member lumen extends longitudinally under the proximal outer 10,
and
houses the pull back wire 45. The retracting member lumen that houses the pull
back
wire 45 may also carry fluid for purging air from the catheter 5.
The invention additionally comprises a collapsible sheath 50 situated
between the proximal outer 10 and the distal sheath 40. The collapsible sheath
50
covers the exposed area between the proximal outer 10 and the distal sheath
40,
serving to orotect the guide wire lumen 15 and the retracting member 45 in
this area.
The collapsible sheath 50 is adhered to the proximal end of the distal sheath
40 at
point 42 and the distal end of the proximal outer 10 at point 48. These
connections
between compor:ents are preferably made using adhesives such as urethane or
cyanoacrylate, and other suitable adhesives that are well known in the art.
Connections between polymer components can also be made using other bonding
techniques such as thermal welding, ultrasonic welding and the like.
The collapsible sheath 50 is manufactured to induce collapsibility by
winding a coil around the collapsible sheath material, such as a tube of
SURLYN.
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The coil winder controls the pitch or distance between adjacent wraps of wire.
After
the tube is wound, the tube is pressurized, causing the material to expand
between the
gaps in the wire and creating the pleats or creases which allow it to
collapse. The coil
is then removed producing the collapsible sheatli 50 behind.
As the distal sheath 40 is retracted, the collapsible sheath 50 is forced
back, collapsing upon itself into an accordion type configuration to give the
distal
sheath 40 room to retract. The collapsible sheath 50 is longer than the distal
sheath 40
and is made from a highly flexible material such as SURLYN, PEBAX, or
polyethylene, including both HDPE and LDPE, but preferably SURLYN. The distal
sheath 40 and the collapsible sheath 50 may be two separate sheaths/components
adhered to one another, or they may form one continuous sheath.
In the preferred embodiment, the distal sheath 40 is connected via a
collar comprised of a short section of hypotube 55, configured as an annular
ring, to
the pull back wire 45. The proximal end of the distal sheath 40 is attached by
adhesive or heat bond to the annular ring 55 and the distal end of the pull
back wire
45 is connected, preferably brazed, to the inside of the annular ring 55.
Although one
pull back wire 45 is preferred, a plurality of pull back wires may be
connected to the
collar 55. The illustrative figures 1-5 enclosed herein utilize two pull back
wires.
Proximal to the stent 35 is a stopper 60. The stopper 60 is preferably
HDPE and is attached to the guide wire lumen 15, or whatever may comprise the
rigid
inner core, and is used to prevent the stent 35 from moving proximally when
the distal
sheath 40 is retracted.
Preferably, the catheter 5 further comprises an optional neck portion 62
located just proximal to the collar 55. This portion 62 is a slight reduction
in diameter
of the catheter 5 just behind the collar 55. The neck portion 62 aids in
containing the
collar 55 and supplies added leverage to the collar 55 as it retracts the
distal sheath 40.
It additionally aids in compressing the collapsible sheath 50 by providing an
added
brace for the collar 55 as the collar pushes back collapsing the collapsible
sheath 50.
In an alternative embodiment a stiffening wire 60, preferably stainless
steel but optionally NITINOL may also be incorporated longitudinally along the
axis
of the catheter 5 for extra stability and control.
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In a fixed wire embodiment the guide wire lumen 15 may be replaced
with just a guide wire, wherein the distal portion of the guide wire 20 is
bonded to the
distal tip 25.
The proximal portion of the catheter 5, as shown in Figures 1-3,
comprises of a manifold system, generally designated 100, which includes a
sliding
member 110 slidably integrated between the distal and proximal end of the
manifold.
By retracting the sliding member 110 of the manifold 100, distal to proximal,
the
distal sheath 40 is retracted exposing the stent 35. The manifold 100 may
further
comprise a hydrating luer 130, which is preferably located on the distal end
of the
manifold 100 and is used to purge air from the catheter.
To prepare the stent delivery catheter 5 the stent 35 is compressed and
loaded into the stent receiving portion 30 and covered by protective distal
sheath 40.
The distal sheath 40 remains covering the underlying stent 35 during the
placement of
the stent 35 by the delivery catheter 5 through the patient's vasculature.
During the
placement of the stent 35, the distal sheath 40 protects the patient's
vasculature from
the stent 35.
Figures 1-3 illustrate three stages of the deployment of a self-expanding
stent 35 using the preferred embodiment of the catheter of the present
invention. .
Figure 1 represents a loaded deployment catheter 5, with the stent 35 covered
by the
distal sheath 40 and the collapsible sheath 50 in its extended state. Figure 2
shows the
stent 35 partially deployed, with the distal sheath retracted to cause the
collapsible
sheath to partially collapse. In the preferred embodiment the pull wire is
attached to
sliding member 110, which is used to retract sheath 40. As the sliding member
110 is
pulled back, the distal sheath 40 begins to retract. The stent is prevented
from
moving proximally with the sheath by the stopper and therefore, the stent 35
begins to
release and expand while the collapsible sheath 50 begins to collapse upon
itself in an
accordion fashion. Since the distal sheath 40 does not slide back over the
proximal
outer, but rather the collapsible sheath 50 collapses in place, the profile of
the catheter
5 remains nearly the same. Figure 3 shows the stent fully released. At this
point the
distal sheath 40 is fully retracted and the collapsible sheath 50 is
compressed releasing
the stent 35 to allow it to self-expand against the vessel wall 65. After the
stent 35 is
expanded and in place, the catheter 5 is withdrawn. It should be understood
that a
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balloon expandable stent could also be utilized by arranging the stent around
an
optional placement balloon (not shown). Once the sheath 40 is fully retracted
the
placement balloon would be inflated through its inflation lumen (not shown) to
deploy the stent.
Preferably the stent 35 is self expanding, such as a NITINOLTM stent,
or it may be expanded by means of an internal balloon positioned under the
stent 35
on the distal end of the inner core 15. Those skilled in the art will
recognize other
suitable materials and constructions which may be employed to serve
substantially the
same function.
The collapsible sheath is formed such that upon retraction of the distal
sheath 40 the collapsible sheath 50 is compressed to a state approximately 1/5
of its
longitudinally expanded state. The collapsible sheath 50 provides covering of
the wire
mechanism, eliminates the relative motion of the proximal edge of the distal
sheath
40 and reduces the friction involved in retraction of the distal sheath 40.
Unlike
known retractable systems, the distal sheath does not retract over or under
the
proximal outer, which results in an increase in the profile of the catheter,
an increase
in friction as the distal sheath resists being pulled back over the proximal
outer and a
higher likelihood of hang ups due to the faulty engagement between the
proximal end
of the distal sheath and the guide catheter or vessel. In the present
invention the
collapsible sheath 50 compresses thereby providing space for the distal sheath
40 to
retract without any encumbrances.
Figures 4 and 5 illustrate an alternative embodiment of the present
invention. In this case the proximal outer 70 extends distally over the
catheter,
generally designated 90, up to a position in close proximity with the stopper
60 and
the collapsible sheath 75 performs as the distal sheath. The distal end of the
proximal
outer 70 is adhered to the proximal end of the collapsible sheath 75 at point
80. In this
embodiment the collar 55 is connected to collapsible sheath 75 at the distal
end at
point 85. As the pull back wire 45 is drawn proximally, the collapsible sheath
75 is
retracted, collapsing upon itself, and begins to release. As discussed
earlier, stopper
60 prevents the stent from moving proximally with the retracting sheath 75.
Figure 5
illustrates the fully retracted collapsible sheath 75 and the release of the
stem 35 to its
fully expanded position urging against the inner wall of the vessel 65.
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Figure 6 discloses an alternative embodiment of the present invention.
in this case the stent delivery system is generally designated 145 and the
catheter 155
is comprised of a guide wire lumen 15 and a pull back lumen 150. The pull back
lumen is axially connected to the guide wire lumen, traveling along the length
of the
guide wire lumen 15 up to the distal tip 25 at point 153, as the guide wire
lumen
continues through the distal tip 25. Figure 7 illustrates the configuration of
the
catheter 155 from a cross-section perspective along lines 7-7 in Figure 6. A
stent 35
may be concentrically arranged around the catheter 15 near the distal end on
the stent
receiving portion 30. The device further comprises a retractable distal sheath
40
surrounding at least a portion of the stent 35. Figure 6 shows the retractable
distal
sheath 40 partly retracted. The proximal end of the retractable distal sheath
40 is
attached to the collapsible sheath 50 at point 143. The collapsible sheath 50
is
concentrically arranged around the catheter 155 and is shown in Figure 6 as
partially
collapsed. The proximal end of the collapsible sheath 50 is connected,
preferably
adhered, to a fixed anchoring device 140, preferably an annular collar, which
is
affixed to the catheter 155 at point 160. The fixed anchoring device 140
stabilizes the
proximal end of the collapsible sheath 50 allowing it to collapse upon itself
during
retraction of the distal sheath 40. The pull back wire 45 travels, proximal to
distal,
through the pull back lumen 150 and exits through an axial slit (not shown) in
the
surface of the pull back lumen 150. The distal end of the pull back wire is
attached to
annular ring 55, which is in turn attached to the retractable distal sheath
40. During
the application of the device the pull back wire 45 is retracted, sliding
proximally
through the axial slit in the pull back lumen, proximally retracting the
distal sheath 40
causing the collapsible sheath 50 to collapse, freeing the stent 35 for
delivery. The
stopper 60 prevents the stent from moving proximally with the retracting
sheath 75.
Figure 8 illustrates a rapid exchange embodiment of the invention. The
distal end of the catheter is structured and functions in the same fashion as
that of
device shown in Figure 1. The overall length of the catheter is approximately
135
cm, while the length of the guide wire lumen 15 is between approximately 5 cm
to 35
cm from the distal tip 25 to a point where the guide wire lumen 15 and the
guide wire
20 exit the catheter.
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It should be understand that other mechanical methods of retracting the
pull back wire, besides the manifold apparatus disclosed herein, may be
employed.
It should also be understood that the retractable distal sheath 40 and the
collapsible sheath 50 may comprise one continuous sheath, wherein the preform
creases or pleats are incorporated only into the intended collapsible portion.
The design disclosed herein also aids in flushing the catheter. Since the
catheter essentially is sealed to the distal tip 25 and has only one opening
in the distal
segment, that being the end portion of the guide wire lumen 15 at the distal
tip 25,
flushing is made easier and more efficient.
The present invention may be incorporated into both of the two basic
types of catheters used in combination with a guide wire, commonly referred to
as
over-the-wire (OTW) catheters and rapid-exchange (RX) catheters. The
construction
and use of both over-the-wire and rapid-exchange catheters are well known in
the art.
The usable length of the delivery catheter is approximately 135 cm. For a
rapid
exchange catheter the distance from where the guide wire accesses the guide
wire
lumen to the distal tip will be approximately 5 cm to 35 cm.
The key features of the longitudinally collapsible sheath include,
without limitation: low profile both proximally and distally when extended,
relatively
thin walls for low profile and large interior lumens, efficient packing upon
collapse,
flexible, pushable and trackable.
A further embodiment of the invention is shown in Figures 9, 9a, 9b
and 9c. This catheter, generally designated 162, is similar to the above
embodiments
in that it focuses on a retractable sheath portion and an accordion portion,
and it
comprises many of the same materials and elements, which function in
substantially
the same manner.
As shown in Fig. 9, the catheter 162 includes a hand manifold,
generally designated 164, which comprises a handle 161, a sheath actuator
(sliding
member) 163. a safety lock 198, which secures the sheath acruator 164 in place
and is
preferably made of polyethylene, a guide wire inlet 165 for controlling the
guide wire
from the proximal end, and a hydrating luer 167, for flushing. The manifold
164 also
comprises a strain relief tubing 190 which is connected to the distal end of
the handle.
The proximal outer shaft 166 extends distally through the strain relief tubing
190. The
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strain relief tubing 190 protects the proxiurial outer shaft 166 at the
shaft's 166 joining
with the manifold 164. Such protection is needed because of the distinct size
difference between the manifold 164 and the proximal outer shaft 166.
The catheter 162 further comprises a proximal outer shaft, or proximal
outer, 166, preferably made of a polyimide braid, a distal outer shaft 168,
preferably
made of polyethylene, connected to the proximal outer shaft 166 at an adhesive
point
192, preferably by means of a urethane adhesive. The distal outer shaft 168 is
similarly connected to a collapsible sheath/sh"ft 174, which is collapsible in
the
longitudinal direction in an accordion manner at a second adhesive point 200
(preferably using a urethane adhesive) and which is most preferably made of
HDPE,
best shown in Fig. 9a. The collapsible shaft 174 is in turn connected to a
proximal
sheath, or spacer sheath, 176, which is preferably made of polyethylene, at a
third
adhesive point 202 (preferably using a urethane adhesive). The distal end of
the
proximal sheath 176 is adhered at point 204 (preferably using a urethane
adhesive) to
the proximal end of a retractable distal sheatll, or deployment sheath, 184,
which is
preferably made of polyethylene, which encloses a loaded stent 196, preferably
a
NITINOL self expanding stent.
The catheter 162 also further comprises an inter-nal guide wire lumen
170, preferably made of a polyimide braid, which may house a guide wire and
which
extends within the catheter 162 from the guide wire inlet 165 to and through a
distal
tip 186, which is preferably made of polyethylene, at the distal end of the
catheter
162, to which it is connected to the distal tip 186, best seen in Fig. 9c,
preferably
using a urethane adhesive 206. The deployment sheath 184 overlaps the distal
tip 186
in a manner which provides the smoothest profile possible. In Fig. 9c, this
"smooth
,25 profile" is achieved by a notch in the outer surface of the distal tip 186
in which the
distal end of the deployment sheath abuts.
Also housed within the catheter is a pull (back) wire lumen 172,
preferably made of polyethylene, which in turn houses the pull (back) wire
182, which
is preferably stainless steel. The pull wire lumen 172, best seen in Figs. 9a
and b, is
optional and can be adhered and separate from the outer wall of the catheter
162, or
can share conunon inner surfaces with the outer wall of the catheter 162. The
pull
wire lumen 172 extends from a point just distal to the sheath actuator 163,
through the
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catheter 162, to a point at the distal end of the proximal sheath 176, best
seen in Fig.
9b. As seen in Fig. 9a, the pull wire lumen may discontinue and recontinue
when
within the collapsible shaft 174. This is to allow the shaft 174 room to
collapse when
the deployment sheath 184 is retracted.
The pull wire 1$2 is housed within the pull wire lumen 172. The
proximal end of the pull wire 182 is attached to the sheath actuator 163 and
the distal
end of the pull wire 182 is connected to a pull collar (annular ring) 178,
preferably
made of stainless steel, which, as seen in Fig. 9b, is connected, preferably
adhered, to
the inner wall of the proximal end of the deployment sheath 184. This collar,
as in the
above embodiments, can be positioned anywhere along the catheter distal to the
collapsible portion, as long as it is connected so that the sheath covering
the stent is
retracted. As in the other embodiments, when the sheath actuator 163 is
retracted, the
deployment sheath is siniilarly retracted, pushing back the proximal sheath
176, which
in turn applies reward pressure on the collapsible shaft, which collapses onto
itself,
resulting in the release of a stent 196.
Fig. 9b further illustrates a stopper/bumper 180, preferably made of
polyethylene, positioned just proximal to the stent 196 used to prevent the
stent 196
from slipping proximally during the retraction of the deployment sheath 184.
The
bumper is preferably adhered to the guide wire lumen 170 using a urethane
adhesive
208 just distal to the pull collar 178 within the deployment sheath 184.
Figs. 9b and 9c also illustrate a pair of optional markerbands 188
positioned at either end of the loaded stent 196 to provide the physician
means to
accurately position the stent within the vascular lumen at the targeted
problem area
where the stent is to be deployed. Any number, or size, of markerbands may be
incorporated, as long as it aids the physician in accurately positioning the
stent.
Preferably, there are two, positioned as seen in Figs. 9b and 9c, and are
adhered to
the guide wire lumen at the proximal and distal ends 194 of the stent 196,
preferably
using an cyanoacrylate adhesive.
The distal outer shaft 168, preferably made of polyethylene, and the
proximal sheath 176, have reduced diameters as compared to the proximal outer
shaft
166 and the deployment sheath 184, respectively, in order to reduce, the
profile of the
collapsible shaft 174. As can be seen in Figs. 9, 9a and 9b, the outside of
the distal
CA 02439320 2006-10-12
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end of the proximal outer shaft 166 is adhered to the inside of the proximal
end of the
distal outer shaft 168. Just distal to this connection, the diameter of the
distal outer
shaft 168 is decreased. Similarly, the outside of the distal end of the distal
outer shaft
168 is adhered to the inside of the proximal end of the collapsible shaft 174.
The
inside of the distal end of the collapsible shaft 174, in turn, is adhered to
the outside
of the proximal end of the proximal sheath 176, which has approximately the
same
diameter of the distal outer shaft 168. The outside of the distal end of the
proximal
sheath 176, finally, is adhered to the inside of the proximal end of the
deployment
sheath, which is notched down so as to be compatible with the outer diameter
of the
distal end of the proximal sheath 176 and to aid in maintaining the position
of the pull
collar 178 during retraction, best seen in Fig. 9b. This type of construction
reduces
the profile of the collapsible shaft 174 when the shaft 174 is collapsed. The
distal
outer shaft 168 and the proximal sheath 176 could be removed so that the
distal end
of the proximal outer shaft 166 is extended and is adhered to the proximal end
of the
collapsible shaft 174, while the proximal end of the deployment sheath 184 is
extended and is adhered to the distal end of the collapsible shaft 174, but
the overall
profile would be compromised.
It should be further noted that the collapsible portion of the catheter
can be located anywhere along the catheter distal to the manifold and proximal
to the
retractable portion in the above embodiments. The collapsible portion can also
be any
length, as long as it is longer than the length of the loaded stent so as to
allow for
clean deployment of the stent.
Any part of the above sheaths of the catheter distal to the collapsible
portion is considered the retractable portion. The retractable portion
proximal to the
pull collar and the shaft/sheath portions proximal to the collapsible portion
must be
rigid enough to resist collapsing upon itself during the sheath retracting
process. The
guide wire lumen also must be rigid enough to resist the reward pressure
during the
retraction of the retractable portion. See U.S. Pat. No. 5,534,007, titled
PULL
BACK SLEEVE SYSTEM WITH COMPRESSION RESISTANT INNER SHAFT.
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The collapsible shaft is constructed so as to collapse upon retraction of
the retractable portion. The following are descriptions of example methods
used in
creating a polyethylene collapsible sheath and a SURLYN collapsible sheath:
Example 1
Process for Po1, etyl ene(pE) Collapsible
Shaft ForminQ
Materials needed:
1. PE tubing 0.041/0.046 (inches) inner/outer diameter
2. Mandrel stock 0.040 (inches)
3. Coil winder
4. Blade with 0.003 radius edge (inches).
5. Rubber Gloves
Protocol:
Step 1. Place the PE tubing onto the mandrel and into coilwinder.
Step 2. Turn coilwinder on at speed 4, with a .020 pitch and set blade at
35 degree angle.
Step 3. Set blade down on PE tube and plow, or contour, the PE tube.
The resulting PE tube will have a small indent circumferentially
around the tube, preferably in a helical fashion.
Step 4. Hold the PE tube on outside of indent and push together so tube
will accordion, preferably with rubber gloves.
Step 5. Leave accordion tube on mandrel for annealing process. Anneal
tube in an oven at 70 degrees C. for a minimum of 4 hours.
The resulting shaft is then prepared to be incorporated into the catheter.
Example 2:
Process for SURLYN Collapsible
Shaft Formine
Materials needed:
1. Razor blades
2. Balloon Mold (preferably 1.5mm)
3. Spring
4. Cold water bath and hot water bath (80 C)
5. Mandrel (preferably TEFLON coated)
6. SURLYN sleeve (blank)
7. Alcohol (99%)
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8. Grooved accordion mold
9. Air pressure station (preferably 95-100 PST)
Protocol:
Step 1.
Load the blank tubing into the mold using the following method:
Load spring into the balloon mold (note: no spring is required with the
grooved accordion mold). Insert tubing blank into mold until
approximately 1i protrudes from proximal end. Place balloon mold into
holding bracket. Insert end of tubing blank into the Y adapter connector
and tighten. Pressurize tube.
Step 2.
Mold the accordion assembly using the following method:
Lower mold into hot water bath up to the Y adapter and then raise until
top edge of mold reaches surface of water. Hold mold in hot water for
25-30 seconds. Lift mold out of water bath and insert into cold water
bath for 3-5 seconds. Remove mold from water and close air stopcock.
Open Y adapter valve and remove tubing. Remove balloon mold from
bracket. Open mold and pull out tubing with spring (if present). Trim
proximal end of tubing to 5mm and remove spring (if present).
Step 3.
Heat set the folds of the accordion assembly using the following
method:
Slide accordion assembly over mandrel. Slide black sleeve over
mandrel and under shaft of accordion assembly up to the folds. Push
both ends of the folds together from each erid and place a clamp onto
the sleeve to hold it in place. Dip assembly into hot water bath a
maximum of 2mm past folds and hold for 10-15 seconds (note: ensure
folds are submerged in the water). Remove and dip mandrel into cold
water bath for 2-5 seconds. Remove from cold water bath and slide
back sleeve and clamp. Slide accordion assembly off mandrel. Rinse
with alcohol and dry with nitrogen.
The resulting shaft is then prepared to be incorporated into the catheter.
It should also be noted that the part of the retractable portion which
covers the loaded stent can also be contoured to increase its flexibility,
preferably in a
helical fashion.
The above disclosiure is intended to be illustrative and not exhaustive.
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These examples and description will suggest many variations and alternatives
to one of
ordinary skill in this art. All these alternatives and variations are intended
to be
included within the scope of the attached claims. Those familiar with the art
may
recognize other equivalents to the specific embodiments described herein which
equivalents are also intended to be encompassed by the claims attached hereto.
