U.S. patent application number 10/043233 was filed with the patent office on 2002-05-16 for large-diameter introducer sheath having hemostasis valve and removable steering mechanism.
Invention is credited to Evans, Michael A., Freislinger, Kirsten, Hermann, George D., Kim, Steven W., Lenker, Jay A..
Application Number | 20020058910 10/043233 |
Document ID | / |
Family ID | 23288475 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020058910 |
Kind Code |
A1 |
Hermann, George D. ; et
al. |
May 16, 2002 |
Large-diameter introducer sheath having hemostasis valve and
removable steering mechanism
Abstract
A catheter introducing system includes an introducer catheter
comprising a flexible sheath having a hemostasis valve and an
obturator having a steering mechanism operated by a proximal
actuator handle. The catheter introducer system will usually be
introduced with the obturator inside of the flexible sheath so that
the obturator can effect steering by laterally deflecting the
distal end of the combined sheath and obturator. Such catheter
introducing systems are particularly useful for large diameter
sheaths which are not readily introduced over guide wires. A first
exemplary hemostasis valve comprises a compressed foam insert
having an axial lumen therein. A second exemplary hemostasis valve
comprises an elastomeric insert which receives and seals over the
catheter.
Inventors: |
Hermann, George D.; (Los
Gatos, CA) ; Freislinger, Kirsten; (Menlo Park,
CA) ; Kim, Steven W.; (Cupertino, CA) ;
Lenker, Jay A.; (Laguna Beach, CA) ; Evans, Michael
A.; (Palo Alto, CA) |
Correspondence
Address: |
MEDTRONIC AVE, INC.
3576 UNOCAL PLACE
SANTA ROSA
CA
95403
US
|
Family ID: |
23288475 |
Appl. No.: |
10/043233 |
Filed: |
January 14, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10043233 |
Jan 14, 2002 |
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09158777 |
Sep 23, 1998 |
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09158777 |
Sep 23, 1998 |
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08735401 |
Oct 21, 1996 |
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08735401 |
Oct 21, 1996 |
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08330140 |
Oct 24, 1994 |
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Current U.S.
Class: |
604/95.04 ;
604/170.02 |
Current CPC
Class: |
A61M 25/0045 20130101;
A61M 2025/0046 20130101; A61M 2210/127 20130101; A61M 25/0051
20130101; A61B 17/12136 20130101; A61M 25/0138 20130101; A61M
2025/1061 20130101; A61M 2025/0681 20130101; A61M 2025/1052
20130101; A61M 2039/0633 20130101; A61M 25/0147 20130101; A61M
2039/0646 20130101; A61F 2/07 20130101; A61M 2039/0686 20130101;
A61M 25/0053 20130101; A61F 2002/065 20130101; A61B 17/12118
20130101; A61B 17/12109 20130101; A61B 17/12036 20130101; A61M
25/005 20130101; A61M 39/0606 20130101; A61M 25/0662 20130101; A61F
2/958 20130101; A61M 2039/062 20130101; A61M 25/0144 20130101; A61M
2039/066 20130101 |
Class at
Publication: |
604/95.04 ;
604/170.02 |
International
Class: |
A61M 031/00; A61M
005/178 |
Claims
What is claimed is:
1. A catheter introducing system comprising: a flexible sheath
having a proximal end, a distal end, and a lumen extending
therebetween; and an obturator removably receivable in the lumen of
the flexible sheath, said obturator having means actuable from a
proximal end thereof for laterally deflecting at least a distal
portion thereof.
2. A catheter introducing system as in claim 1, wherein the
obturator has an outer diameter which is at least 75% of the inner
diameter of the sheath.
3. A catheter introducing system as in claim 2, wherein the
obturator has a tapered distal end which defines a smooth
transition with the distal end of the sheath.
4. A catheter introducing system as in claim 3, wherein the
obturator has a length which is in the range from one to one and
one-half times that of the flexible sheath.
5. A catheter introducing system as in claim 3, wherein the
obturator has a length which is at least twice that of the flexible
sheath.
6. A catheter introducing system as in claim 1, wherein the
flexible sheath has a length in the range from about 30 cm to 60 cm
and a lumen diameter in the range from about 4 mm to 10 mm and
wherein the obturator has a length in the range from 35 cm to 65 cm
and an outer diameter in the range from about 4 mm to 9 mm.
7. A catheter introducing system as in claim 6, wherein the
obturator comprises an elongate body having a region of enhanced
flexibility over the distal length in the range from 3 cm to 6
cm.
8. A catheter introducing system as in claim 7, wherein the region
of enhanced flexibility is articulated.
9. A catheter introducing system as in claim 7, wherein the
flexible sheath has a region of enhanced flexibility over a distal
length in the range from 5 cm to 15 cm.
10. A catheter introducing system as in claim 1, wherein the
deflecting means comprises a pull wire attached off center at the
distal end of the obturator.
11. A method for introducing a flexible sheath to a target location
in a body lumen, said method comprising: introducing the sheath to
the body lumen; advancing the sheath within the lumen toward the
target location while laterally deflecting at least a distal
portion of an obturator which is removably received in a lumen of
the sheath; and removing the obturator from the sheath to provide
an access lumen through the sheath after reaching the target
location.
12. A method as in claim 11, wherein the laterally deflected distal
portion of the obturator is positioned within a distal portion of
the sheath while the sheath and obturator are advanced
together.
13. A method as in claim 11, wherein the sheath is advanced over
the obturator after the obturator has been advanced toward the
target location.
14. A method as in claim 11, wherein the target location is the
aorta and sheath and obturator are advanced through the subclavian,
external carotid, or axillary artery and the aortic arch to the
aorta.
15. A method as in claim 14, wherein the sheath has a length in the
range from 30 cm to 60 cm and an access lumen diameter in the range
from about 5 mm to 10 mm.
16. A method as in claim 14, further comprising expanding a member
on the exterior of the sheath within the aorta to partially occlude
blood flow.
17. A method as in claim 14, further comprising introducing a
vascular graft through the access lumen into the aorta, the right
iliac, or the left iliac.
18. A method as in claim 17, further comprising expanding a member
on the exterior of the sheath within the vascular graft after said
graft has been positioned at the target location in order to anchor
the graft at said target location.
19. An aortic introducer catheter comprising: a flexible sheath
having a proximal and, a distal end, and a lumen extending
therebetween wherein the length between the proximal and distal
ends is in the range from 30 cm to 60 cm and the lumen diameter is
in the range from 5 mm to 10 mm, and a hemostasis valve secured to
the proximal end of the sheath.
20. An aortic introducer catheter as in claim 19, wherein the
flexible sheath has a region of enhanced flexibility over a distal
length in the range from 5 cm to 15 cm.
21. An aortic introducer catheter as in claim 19, further
comprising an expandable member on the exterior of the sheath
located at from 1 cm to 10 cm from the distal end of the sheath,
wherein said expandable member partially occludes blood flow when
expanded inside the aorta.
22. A aortic introducer catheter as in claim 19, further comprising
an expandable member at the distal end of the sheath, wherein said
expandable member can be positioned within an aortic prosthesis for
internal expansion.
23. An aortic introducer catheter as in claim 19, wherein the
flexible sheath comprises: a tubular inner liner having a proximal
end, a distal end, and a lumen therebetween; a flat wire helical
coil wrapped over an exterior surface of the tubular inner liner,
said coil having spaced-apart adjacent turns; and a plastic coating
formed over the helical coil, penetrating into the space between
adjacent turns of the coil, and bonded to the tubular inner
liner.
24. An aortic introducer catheter as in claim 19, wherein the
hemostasis valve comprises: a housing having an interior and
axially aligned inlet and outlet ports; and a compressible insert
disposed within the interior of the housing, said insert including
a polymeric foam body having an open axial lumen and an exterior
geometry which is similar to but larger than the cavity in the
housing, wherein the insert is confined within the cavity to close
the lumen with said closed lumen being aligned between the inlet
and outlet ports.
25. A catheter sheath comprising: a tubular inner liner having a
proximal end, a distal end, and a lumen therebetween; a flat wire
helical coil wrapped over an exterior surface of the tubular inner
liner, said coil having spaced-apart adjacent turns; and a plastic
coating formed over the helical coil, penetrating into the space
between adjacent turns of the coil, and bonded to the tubular inner
liner.
26. A catheter sheath as in claim 25, wherein the tubular liner is
composed of a material selected from the group consisting of
polyurethane, polytetrafluoroethylene, fluorinated
ethylene-propylene polymer, polyether block amide copolymer,
polyamide, and polyethylene and has a wall thickness in the range
from 0.08 mm to 0.15 mm.
27. A catheter sheath as in claim 25, wherein the helical coil
comprises a stainless steel ribbon having a width in the range from
0.5 mm to 1.5 mm and thickness in the range from 0.08 mm to 0.15
mm, wherein the ribbon is wrapped at from 5 turns to 15 turns per
cm and wherein the spacing between adjacent turns is in the range
from 0.5 mm to 1 mm.
28. A catheter sheath as in claim 25, wherein the plastic coating
is composed of a material selected from the group consisting of
polyurethane, polyether block amide copolymer, polyethylene, and
polyamide, and has a thickness measured from tubular inner liner in
the range from 0.08 mm to 0.15 mm.
29. A catheter sheath as in claim 25, having a region of enhanced
flexibility over a distal length in the range from about 5 cm to 15
cm.
30. A catheter sheath as in claim 25, having a soft tip free from
the helical coil over a distal length in the range of 2 mm to 10
mm.
31. A catheter sheath as in claim 25, further comprising a
hemostasis valve secured to the proximal end of the sheath.
32. A steerable obturator for use with a flexible catheter sheath,
said obturator comprising: a flexible body having a proximal end
and tapered distal tip; and means for laterally deflecting at least
a distal portion of the flexible body.
33. A steerable obturator as in claim 32, wherein the catheter body
has a length in the range from 45 cm to 60 cm and an outer diameter
in the range from 4 mm to 5 mm.
34. A steerable obturator as in claim 33, wherein the catheter body
has a region of enhanced flexibility over a distal length in the
range from about 5 cm to 10 cm.
35. A steerable obturator as in claim 33, wherein the region of
enhanced flexibility is articulated.
36. A steerable obturator as in claim 32, wherein the deflecting
means comprises a pull wire attached off center at the distal end
of the flexible body.
37. A steerable obturator as in claim 36, wherein the deflecting
means further comprises a handle assembly attached to the proximal
end of the flexible body, wherein said handle assembly includes a
first portion attached to the pull wire and a second portion
attached to the flexible body, whereby relative movement of the two
portions causes lateral deflection of the tip.
38. A hemostasis valve comprising: a housing having an interior
cavity and axially aligned inlet and outlet ports; and a
compressible insert disposed within the interior cavity of the
housing, said insert including a polymeric foam body having an open
axial lumen and an exterior geometry which is similar to but larger
than the cavity in the housing, wherein the insert is confined
within the cavity to close the lumen with said closed lumen being
aligned between the inlet and outlet ports.
39. A hemostasis valve as in claim 38, further comprising a second
valve element in series with the compressible insert.
40. A hemostasis valve as in claim 39, wherein the second valve
element is a duck bill or a slit disk structure.
41. A hemostasis valve as in claim 38, wherein the lumen is coated
with a lubricant.
42. A hemostasis valve as in claim 38, wherein the lumen is coated
with a protective layer.
43. A hemostasis valve as in claim 42, wherein the coating material
is selected from the group consisting of polyurethane and
silicone.
44. A hemostasis valve comprising: a housing having an interior
cavity and axially aligned inlet and outlet ports; and an
elastomeric insert within the interior cavity of the housing, said
insert having a forwardly disposed conical face, wherein the face
is radially split to permit passage of a catheter therethrough.
45. A hemostasis valve as in claim 41, wherein the insert further
includes an annular ring disposed proximally of the forwarding
disposed face.
Description
[0001] This application is a continuation of application Ser. No.
08/735,401, filed on Oct. 21, 1996, which is a divisional of
application Ser. No. 08/330,140, filed Oct. 24, 1994, and are
hereby incorporated by reference for all purposes.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to apparatus and
methods for introducing devices to target locations within body
lumens and cavities. In particular, the present invention relates
to introducing catheters and methods which are used to provide
large-diameter access lumens to target locations disposed along or
at the distal end of tortuous paths.
[0004] Introducer sheaths and catheters are commonly used to
provide endoluminal and/or percutaneous access to remote target
locations in a variety of medical procedures, including
intravascular procedures, laparoscopic procedures, and other
minimally invasive procedures. Of specific interest to the present
invention, the endovascular placement of vascular grafts for the
treatment of abdominal aortic aneurysms has been proposed, where
the graft may be inserted into the aorta via an antegrade or
retrograde arterial approach. Such endovascular graft placement
will require the use of a relatively large graft placement
catheter, typically having an outer diameter in the range from 4 mm
to 10 mm. Such large placement catheters will require
correspondingly large introducing catheters or sheaths, typically
having an internal lumen diameter which is at least slightly larger
than the outer diameter of the placement catheter. The placement
and use of such large-diameter introducing catheters or sheaths
will be problematic in several respects.
[0005] In particular, the antegrade path into the subclavian
artery, through the aortic arch, and into the thoracic aorta is
quite tortuous. While the path can be readily negotiated by
conventional intravascular guide wires, such guide wires have very
small diameters and are not sufficiently strong to permit
introduction of a large diameter introducing sheaths thereover. To
overcome this problem, it would be possible to employ an
introducing sheath having an integral steering mechanism. Such
sheaths could be introduced around even the very tight curves
encountered in the transition from the subclavian artery to the
aortic arch. The incorporation of a steering mechanism, however,
necessarily reduces the lumen area of the sheath which is
ultimately available for accommodating the graft-placement
catheter.
[0006] Other problems which arise when introducing sheaths are used
for aortic access include the design of the hemostasis valve. The
hemostasis valve must be able to accommodate very small devices,
such as guide wires, as well as the very large graft-placement
catheter. The body of the sheath must have a very thin wall (to
maximize available area in the access lumen), and a very smooth
lumen to permit the passage of the graft-placement catheters
without sticking or constriction of the catheter. Additionally,
placement of vascular grafts through an introducing sheath located
in the abdominal aorta is further made difficult by the relatively
high blood flow rate through the aorta. Moreover, the ability to
anchor the vascular graft within the aorta and/or adjoining iliac
arteries can be problematic and require additional devices which
are difficult to provide through the limited area of the access
lumen.
[0007] For these reasons, it would be desirable to provide improved
catheter introducing systems and methods, including catheter
sheaths, sheath steering mechanisms, hemostasis valves, and the
like, which overcome at least some of the deficiencies described
above. The introducing sheaths should have a large lumen diameter,
typically being at least 4 mm, to accommodate large diameter
graft-placement catheters, should have good hoop strength to avoid
kinking or collapse of the sheath when bent around tight curves,
and should have good column and tensile strengths to avoid
deformation when the graft-placement catheter is passed through the
lumen. The sheath steering mechanisms should provide for a high
degree of lateral deflection at the distal end of the sheath but
should not take up lumen area which is necessary for subsequent
passage of large diameter catheters. The hemostasis valves should
be able to accommodate both small diameter devices, such as guide
wires, and the large diameter catheters while still maintaining a
tight seal around the catheter to prevent leakage.
[0008] 2. Description of the Background Art
[0009] A steerable sleeve for use in combination with a flexible
catheter is described in DE 39 20 707. U.S. Pat. No. 4,976,688
shows a steerable sheath structure. European Patent Application 488
322 shows a tubular device having a variable curvature controlled
by differential pressure. Other catheter- and device-steering
mechanisms are described in U.S. Pat. Nos. 5,109,830; 5,098,412;
5,019,040; 4,983,165; 4,066,070; and 3,941,119.
[0010] A large-diameter introducer sheath having metal-ribbon
reinforcement and a proximal hemostasis valve is described in U.S.
Pat. No. 5,180,376. Devices covered by the '376 patent are sold by
Arrow International, Inc., Reading, Pa. 19605, under the name super
Arrow Flex.TM. percutaneous sheath introducer set with integral
side port/hemostasis valve. Other reinforced tubular catheter
designs are described in U.S. Pat. Nos. 5,279,596; 5,275,152;
5,226,899; 5,221,270; 5,221,255; 5,069,217; 4,985,022; and
4,411,655.
[0011] U.S. Pat. No. 5,207,656, discloses a hemostasis valve having
a foam member for sealing against a catheter passed therethrough.
The foam member has a lubricant absorbed in an open-cell foam
structure. U.S. Pat. No. 4,475,548, discloses a foam sealing member
for use in an endotracheal tube. European patent application
567,141 describes a trocar valve assembly which may include a
flexibly resilient material for reception of an instrument passed
through the valve. Other hemostasis and similar valve structures
are described in U.S. Pat. Nos. 5,338,313; 5,300,034; 5,279,597;
5,242,425; 5,222,948; 5,215,537; 5,167,636; 5,127,626; 5,104,389;
and 4,177,814.
SUMMARY OF THE INVENTION
[0012] The present invention provides apparatus and methods for
placement of a flexible introducer sheath at a target location in a
body lumen or cavity. Placement of the flexible sheath is usually
percutaneous, i.e., through a puncture or incision in the patient's
skin, and endoluminal i.e., through a body lumen or cavity which
has been accessed through the percutaneous puncture site. An
exemplary use of the apparatus and methods of the present invention
is placement of a flexible sheath through the subclavian or
brachial arteries, through the aortic arch, and into the abdominal
aorta for the delivery of a vascular graft intended for treatment
of an abdominal aneurysm. The apparatus and methods of the present
invention, however, are not limited to use in such graft placement
procedures and may find additional uses in a wide variety of
procedures, including laparoscopic and other minimally invasive
procedures where it is desired to introduce a large diameter sheath
into a body cavity or lumen and subsequently steer or manipulate
the distal end of the sheath to a target location within the
luminal cavity.
[0013] In a first aspect of the present invention, a catheter
introducing system comprises a flexible sheath having a proximal
end, a distal end, and an access lumen extending therebetween. An
obturator is removably received in the lumen of the flexible sheath
and includes a mechanism for laterally deflecting at least a distal
portion of the obturator. In this way, the distal end of the
flexible sheath can be manipulated using the obturator to
facilitate intravascular or other placement of the sheath. After
the sheath has been introduced to the desired target location, the
obturator may be withdrawn, leaving the access lumen open to
receive guide wires, working catheters, and the like. Since the
size of the obturator is limited only by the area of the sheath
access lumen, there is sufficient available cross-sectional area.
for providing effective and efficient steering mechanisms. In
particular, it will be possible to provide steering mechanisms
which are capable of inducing small-radius deflections in the
distal end of the sheath, typically as low as one cm.
[0014] In a second aspect of the present invention, a method for
introducing a flexible sheath to a target location in a body lumen
comprises introducing the sheath to the lumen and advancing the
sheath within the lumen while laterally deflecting at least a
distal portion of an obturator which is removably received in a
lumen of the sheath. The obturator is removed from the sheath after
the target location has been reached in order to provide the
desired access lumen. Usually, the obturator will be within the
sheath with its deflectable distal end axially aligned with a
distal portion of the sheath having enhanced flexibility.
Alternatively, the obturator could be advanced distally beyond the
sheath, using the steering mechanism to reach the desired target
location, with the sheath then being advanced over the obturator.
The method is particularly useful for introducing the sheath into
the subclavian, external carotid, axillary, or brachial arteries,
through the aortic arch, and into the abdominal aorta, but can also
be used for a variety of procedures as described above.
[0015] In a third aspect of the present invention, an aortic
introducer catheter comprises a flexible sheath having a proximal
end, a distal end, and an access lumen extending therebetween. The
length between the proximal and distal ends is in the range from 30
cm to 60 cm and the lumen diameter is in the range from 4 mm to 10
mm. A hemostasis valve is secured to the proximal end of the
sheath, and the aortic introducer catheter is particularly useful
for providing an access lumen into the subclavian or brachial
arteries, through the aortic arch, and into the abdominal aorta.
The catheter preferably has a region of enhanced flexibility over a
distal length in the range from 5 cm to 15 cm so that it may be
utilized in combination with a steerable obturator, as described
above. The aortic introducer catheter may further comprise an
expandable member, typically an inflatable balloon, located at from
1 cm to 10 cm from its distal end where the expandable member can
be used to partially occlude blood flow when expanded inside the
aorta. The catheter may additionally or alternatively, include an
expandable member, again typically an inflatable balloon, at its
distal end, where the distal expandable member can be used for
anchoring an aortic prosthesis by internal expansion.
[0016] In a fourth aspect, the present invention provides a
catheter sheath comprising a tubular inner liner having a proximal
end, a distal end, and a lumen therebetween. The inner liner will
preferably be formed from a lubricous material or have its inner
lumen coated with a silicone gel or other lubricating material.
Flat wire helical coil is wrapped over the exterior surface of the
tubular inner liner, and the coil has spaced-apart adjacent turns.
Plastic coating is formed over the helical coil and penetrates into
the space between the adjacent turns. The coating bonds to the
inner liner to provide an integral structure having a thin wall
with controlled flexibility. The sheath preferably has a region of
enhanced flexibility near its distal end, where flexibility can be
controlled by utilizing liner materials, plastic coating materials,
or both, having lower durometers near the distal end.
Alternatively, the flexibility can be controlled by utilizing
different helical coil materials or by modifying the spacing
between adjacent coil turns to enhance the flexibility. The
catheter sheaths will also preferably have a soft tip over a distal
length in the range from 2 mm to 10 mm. The soft tip will usually
be free from the helical coil and may optionally be formed from a
material having a lower durometer.
[0017] In a fifth aspect of the present invention, a steerable
obturator is provided comprising a flexible body having a proximal
end and a tapered distal end. A mechanism will be provided in the
body for laterally deflecting at least a distal portion of the
body. Typically, the lateral deflection mechanism will comprise a
pull wire which is attached off center at the distal end of the
flexible body. The pull wire can be actuated by a handle secured to
the proximal end of the body. The obturator will preferably have a
region of enhanced flexibility at its distal length, where the
region of enhanced flexibility may comprise a series of articulated
elements.
[0018] In a sixth aspect, the present invention provides a
hemostasis valve comprising a housing having an interior cavity and
axially aligned inlet and outlet ports. A compressible insert is
disposed within the interior cavity of the housing and includes a
polymeric foam body having an open axial lumen in an exterior
geometry which is similar to but larger than the interior cavity in
the housing. By confining the foam insert within the interior
cavity of the housing, the open lumen will be closed to provide a
seal between the axial lined ports of the housing. The
circumference of the lumen, however, will be sufficiently large to
accommodate even large diameter catheters and devices subsequently
introduced through the valve. The particular advantage of this
design is that the lumen in the foam insert will not be stretched
or torn as the catheter is being introduced therethrough. That is,
the original cross-sectional circumference of the lumen will remain
even though the lumen has been collapsed by external compression.
Preferably, the hemostasis valve will include a second valve
element, such as a duckbill or slit disc structure to provide for
hemostasis when no catheter or device is placed through the foam
insert. The lumen of the foam insert will also preferably be coated
with a lubricant and optionally provided with a protective layer to
further guard against tearing of the foam as the catheter is passed
therethrough.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a prospective view of the catheter introducing
system constructed in accordance with the principles of the present
invention and including a flexible sheath and an obturator having a
laterally deflectable distal end.
[0020] FIG. 2 is a prospective view of the catheter introducing
system of FIG. 1, shown with the obturator located in an axial
lumen of the flexible sheath, with a laterally deflected distal end
shown in broken line.
[0021] FIG. 3 is a partial cross-sectional view of a hemostasis
valve mounted at the proximal end of the flexible sheath of the
catheter introducing system of FIG. 1.
[0022] FIG. 4 is a cross-sectional view of a foam insert included
in the hemostasis valve of FIG. 3.
[0023] FIG. 5 is a partial cross-sectional view of the body of the
flexible sheath of the catheter introducing system of FIG. 1.
[0024] FIG. 6 is a side view of an alternate construction of the
flexible sheath of the catheter introducing system of the present
invention.
[0025] FIG. 7 is a cross-sectional view taken along line 7-7 of
FIG. 6.
[0026] FIG. 8 is a proximal end view of a hemostasis valve on the
flexible sheath of FIG. 6.
[0027] FIG. 9 is a side view of the obturator of the catheter
introducing system of FIG. 1 shown with portions broken away.
[0028] FIG. 10 illustrates an alternative construction of the
laterally deflectable distal end of the obturator of FIG. 9.
[0029] FIGS. 11A-11E illustrate use of the catheter introducing
system of FIG. 1 for introducing a vascular graft through the
subclavian artery, aortic arch, and abdominal aorta.
[0030] FIG. 12 is a partial cross-sectional view of an alternative
hemostasis valve which can be mounted at the proximal end of the
flexible sheath of the catheter introducing system of FIG. 1.
[0031] FIG. 13 is a front view of an elastomeric insert included in
the hemostasis valve of FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] The present invention provides a catheter introducing system
including both a large diameter sheath and a steerable obturator
which can be removably introduced into a central lumen of the
sheath. The sheath is usually part of an introducer catheter having
a hemostasis valve at its proximal end. The sheath and obturator
are usually introduced together through a percutaneous access site
to a desired target location within a body lumen or cavity, with
the steerable obturator being used to guide the sheath through a
tortuous path such as in a blood vessel or within an open body
cavity, such as in an insufflated abdomen during a laparoscopic
procedure. Alternatively, the obturator could be advanced distally
beyond the sheath, with the sheath being subsequently advanced over
the obturator. In either case, the obturator is removed after the
sheath reaches the target location, providing an open access lumen
for subsequent introduction of interventional or other catheters
and devices. The catheter introducing system of the present
invention is particularly useful for introducing large diameter
interventional catheters, especially into the brachial or
subclavian arteries, through the aortic arch, and into the
abdominal aorta, more especially for graft placement to treat
abdominal aortic aneurysms.
[0033] The sheath of the catheter introducing system will
preferably include only a single lumen having a relatively large
diameter, usually being at least 4 mm, preferably being from 4 mm
to 10 mm, and more preferably being from 5 mm to 9 mm. For use in
the exemplary aortic introducing catheter, the sheath will have a
lumen diameter from 7 mm to 8 mm, and an outer diameter from 8 mm
to 9 mm. In order to maximize available lumen area (which is an
objective of the design of the catheter introducing system), the
sheath will have a thin wall, usually being from 0.25 mm to 1 mm.
The sheath length will vary depending on the intended use,
typically being from 30 cm to 60 cm. For use in the exemplary
aortic introducer catheter, the sheath length will be from 40 cm to
60 cm, usually being from 40 cm to 50 cm.
[0034] The body of the flexible sheath must have sufficient hoop
strength in order to avoid kinking and collapse during use, even
when the sheath is bent through a small radius curve, preferably as
small as about 1 cm. The sheath must also have sufficient column
strength so that it can be advanced through restricted passages
(although the obturator present in the sheath lumen will contribute
significantly to its effective column strength). To meet these
mechanical requirements, the sheath of the present invention will
preferably be reinforced, such as by an imbedded metal coil, braid,
filament(s), or the like. In a preferred aspect of the present
invention, as illustrated in the exemplary embodiments below, the
sheath will be reinforced with a helical coil formed from a flat
metal ribbon, usually a stainless steel ribbon. The stainless steel
ribbon preferably has a width in the range from about 0.5 mm to 1.5
mm and a thickness in the range from about 0.08 mm to 0.15 mm. In a
particularly preferred construction, the ribbon is wrapped over an
inner liner (as described below) having from 5 turns to 15 turns
per centimeter, wherein the spacing between the adjacent turns is
in the range from 0.5 mm to 1 mm.
[0035] In the exemplary embodiment, the inner liner may be formed
from a lubricous material, such as polytetrafluorethylene (PTFE),
fluorinated ethylenepropylene polymer (FEP), polyether block amide
copolymer (pebax), polyamide (nylon), polyethylene, and the like.
The tubular inner liner will typically have a thickness in the
range from about 0.08 mm to 0.15 mm. The inner liner may also be
formed from a non-lubricous material, such as a polyurethane, where
the inner lumen of the liner is coated with a lubricating material,
such as a silicone gel. Optionally, the lubricating layer may also
be used with other, more lubricous materials, in order to provide
even greater lubricity for the introduction of instruments and
devices through the sheath. The helical coil will be wrapped over
the inner liner, and an outer plastic coating will be melted or
otherwise impregnated over the coil and into the space between
adjacent turns of the coil. The plastic coating is preferably
composed of a material which has elastic properties similar to
those of the liner. Suitable materials include polyurethane,
polyethylene (pebax), polyamide (nylon), and the like. The
thickness of the coating measured from the inner liner to the
exterior of the sheath is typically in the range from 0.8 mm to
0.15 mm. In a preferred construction, both the inner liner and the
outer plastic coating are composed of polyurethane, and the lumen
of the combined inner and outer liner assembly is coated with a
silicone, hydrophilic, or other lubricant. Such lubricating
coatings are well described in the patent literature. See, for
example, U.S. Pat. No. 4,898,591, which is incorporated herein by
reference.
[0036] In a preferred aspect of the present invention, the flexible
sheath will have regions of differing flexibility over its length,
preferably having a region of enhanced flexibility over a distal
length in the range from about 5 cm to 15 cm, more preferably from
5 cm to 10 cm. Such enhanced flexibility may be achieved by
increasing the spacing between adjacent turns of the reinforcement
coil (thus providing reduced reinforcement in the enhanced
flexibility region), utilizing materials for the inner liner and/or
outer plastic coating having lower durometers, selectively reducing
wall thickness, or by other conventional techniques.
[0037] The flexible sheath of the catheter introducing system will
also preferably have a soft tip formed over the distal 2 mm to 10
mm of the sheath body. The soft tip may be formed by terminating
the reinforcement in the soft tip region. Additionally or
alternatively, the softness of the tip can be enhanced by utilizing
the same or different materials for the inner liner and/or outer
coating, where the materials have a lower durometer in the soft tip
region.
[0038] The flexible catheter sheath of the catheter introducing
system may be fabricated by methods well known in the art. In an
exemplary method, the inner layer is formed by wrapping a strip of
the desired plastic material, e.g., a polyurethane, over a mandril,
typically a teflon rod having the desired final inner lumen
diameter. A stainless steel reinforcement ribbon is next wrapped
helically over the polyurethane. Next, another strip of the desired
plastic coating material, e.g., polyurethane, is wrapped over the
stainless steel reinforcement. A shrink wrap tube may then be
placed over the entire assembly, and the assembly cured in an oven
at a temperature sufficient to melt both the inner layer material
and outer layer plastic coating material and to cause shrinkage of
the shrink tube to apply compressive pressure. The shrink tube is
then removed and the flexible sheath cut to the desired length.
Optionally, a silicone, hydrophilic, or other lubricant is then
coated over the interior surface of the sheath lumen to facilitate
introduction and withdrawal of instruments and devices though the
sheath. Such a manufacture results in a generally tapered distal
end of the flexible sheath when the metal reinforcement band is
terminated at the desired distance from the distal tip.
[0039] The introducer catheter of the present invention will
include a hemostasis valve secured to the proximal end of the
sheath. A wide variety of hemostasis valves would be suitable,
including the valves described in U.S. Pat. Nos. 5,338,313;
5,300,034; 5,279,597; 5,242,425; 5,222,948; 5,317,537; 5,207,656;
5,127,626; 5,109,389; and 4,177,814, the full disclosures of which
are incorporated herein by reference. The introducer catheter of
the present invention, however, preferably employs a hemostasis
valve construction which provides for tight lateral sealing against
catheters having a wide range of outside diameters, e.g., from
guide wires to catheters as large as 30 French (10 mm; one French
(F) equals 0.33 mm), often as large as 26 F, and preferably as
large as 22 F.
[0040] A first exemplary hemostasis valve construction employs a
foam insert having an axial lumen. The foam can be an open cell
foam, a closed cell foam, or combination thereof. Suitable foam
materials include silicones, polyurethanes, polyethylenes, and the
like. The foam insert will be contained within a housing having an
interior cavity with axially aligned inlet and outlet ports. The
foam insert will be oversized, with the axial lumen being open when
the insert is an uncompressed state. Usually, the open diameter of
the lumen is at least 0.5 mm, preferably being in the range form
0.5 mm to 5 mm. When the foam insert is disposed within the
interior housing of the cavity, however, the insert will be
compressed sufficiently to close the lumen. The resilient nature of
the foam will permit the lumen to reopen as the catheter is
advanced therethrough. Since the original periphery of the lumen is
maintained (albeit compressed), even large catheters up to the
original diameter of the lumen (or even slightly larger) will be
able to reopen the lumen without tearing or overextending the
lumen.
[0041] In a particular aspect of the first exemplary hemostasis
valve, a second valve element will be provided in series with the
foam insert. Typically, the second element will be a duck bill or
slit valve structure intended to close the hemostasis valve when no
catheter is present in the valve. The lumen of the foam insert may
also be covered with a protective layer and/or coated with a
lubricant. The protective layer will be composed of a material
which is sufficiently flexible to open and close with expansion of
the lumen but which is sufficiently tough to further protect
against tearing or disintegration of the foam insert, preferably
being a polyurethane, a silicone, polyvinyl alcohol, or the
like.
[0042] An alternative hemostasis valve construction employs an
elastomeric insert contained within a housing having an interior
cavity with axially aligned inlet and outlet ports. The elastomeric
insert has a generally cylindrical shank with a forwardly disposed
conical face. The conical face is radially split to form at least
three "petals" which will open as catheters pass therethrough.
Pressure downstream of the valve will hold the conical face closed
when no catheter is present. Optionally, the elastomeric insert may
include an annular ring disposed proximally of the forward conical
face. The annular ring will provide structural support (hoop
strength) for the insert and may provide a sliding seal against
catheters which pass therethrough.
[0043] The flexible sheath of the present invention may further
include a first expandable member, typically an inflatable balloon,
located at from 1 cm to 10 cm from the distal end of the sheath.
The balloon is located on the exterior of the sheath body and
intended to at least partially occlude blood flow when the sheath
is present in a blood vessel, usually the aorta when the sheath is
part of an aortic introducer catheter. A second expandable member
may also or alternatively be disposed near the distal end of the
sheath in order to anchor the sheath at a desired location.
Particular use of the distal expandable member, which will also
typically be a balloon, is to internally expand a vascular
prosthesis, such as a vascular graft, in procedures such as the
placement of vascular grafts in order to treat abdominal aortic
aneurysms.
[0044] The steerable obturator which forms part of the catheter
introducing system comprises a flexible body having a proximal end
and a distal tip. The distal tip will usually be closed, typically
being tapered or blunt. The mechanism for laterally deflecting at
least a distal portion of the flexible body provides the desired
steering capability. The obturator will typically have a length
which is at least equal to that of the flexible sheath so that the
laterally deflectable (steerable) distal end of the obturator can
be aligned with the distal, enhanced flexibility region of the
sheath. In this way, when the obturator is present within the
sheath, the obturator can be used to steer the sheath to desired
target locations as will be described in more detail below. In some
cases, it may be desirable to provide obturator having lengths
substantially greater than that of the associated flexible sheath
which is part of the catheter introducing system. In those cases,
it will be possible to advance the obturator beyond the distal end
of the sheath and subsequently advanced the sheath over the
obturator, after the obturator has reached desired target location.
Thus, the length of the obturator will typically be in the range
from 50 cm to 75 cm, preferably being from 45 cm to 60 when it is
intended to match the sheath length.
[0045] The diameter of the flexible body of the obturator will
usually be slightly less than that of the lumen diameter of the
flexible sheath, typically being about 0.5 mm to 1 mm less than the
lumen diameter. Such a close tolerance is desirable since it
assures that the flexible sheath will conform closely to the
obturator which in turn facilitates steering of the sheath using
the obturator.
[0046] The flexible body of the obturator can be formed from a
variety of materials, typically being a polymer such as
polyurethane, pebax, nylon, or other thermoplastic elastomer.
Usually, the distal portion of the obturator which is intended to
be laterally deflected, i.e., steered, will have a substantially
greater flexibility than the proximal portions of the obturator.
The length of the enhanced flexibility (steerable) region of the
obturator will usually correspond to that of the enhanced
flexibility distal portion of the sheath, typically being from 5 cm
to 15 cm, preferably from 5 cm to 10 cm. Such flexibility can be
enhanced by appropriately choosing the material of the distal
portion, the durometer of the distal portion, and optionally by
mechanically modifying the body to have enhanced flexibility. For
example, the body may include a series of partial cuts along the
side which will be expected to have the greater radius when the
distal end is laterally deflected.
[0047] Alternatively, and in some cases preferably, the enhanced
flexibility distal portion of the obturator may be formed as a
plurality of articulated members, such as pivotally attached links.
An internal spring may be disposed within the links in order to
provide a desired counter force against the lateral deflection
mechanism, as described in more detail below. Each link will
typically have a length from 0.5 cm to 1.5 cm with a total number
of links from 3 to 6. Individual links can be formed from any
medically acceptable material having sufficient strength and
rigidity, such as stainless steel, polycarbonate, glass-reinforced
acetyl resin thermoplastic (such as Delrin.RTM.), and the like.
[0048] A variety of catheter steering mechanisms are known in the
art which can be employed in the obturator of the present
invention. Usually, lateral deflection in only a single direction
will be provided. The obturator and flexible sheath may then be
rotated about their respective axes in order to direct the
combination in the desired direction. Such a steering mechanism can
be readily fabricated using a single pull wire which is connected
off center at the distal end of the obturator.
[0049] The steering mechanism will further include an actuating
handle at the proximal end of the flexible obturator body. In the
case of a single pull wire steering mechanism, the actuator handle
will include a first element attached to the flexible body and a
second element attached to the pull wire. By properly translating
the first and second elements relative to each other, the desired
lateral deflection can be induced in the distal tip of the
obturator.
[0050] Referring now to FIGS. 1-5, a catheter introducing system 10
constructed in accordance with the principles of the present
invention includes an introducing catheter 12 and an obturator 14.
The introducing catheter 12 in turn comprises a flexible sheath 16
and a hemostasis valve assembly 18. The obturator 14 includes both
a flexible body portion 20 and an actuator handle 22. As
illustrated in FIG. 1, the obturator is withdrawn from the central
lumen 24 (FIG. 5) of the flexible sheath 16. FIG. 2 illustrates the
obturator 14 in place within the introducer catheter 12 with a
tapered distal tip 26 extending from the distal end 28 of the
sheath 16. As will be described in greater detail below, proximal
retraction of actuator handle 22 relative to thumb lever 30 causes
lateral deflection of a distal portion of both the obturator 14 and
the flexible sheath 16 which is disposed over the obturator.
Preferably, at least the flexible sheath will have enhanced
flexibility over the region which is laterally deflected.
[0051] As best shown in FIG. 3, hemostasis valve assembly 18
comprises a housing 36 having a foam insert 38 disposed therein.
The housing defines axially aligned inlet and outlet ports 40 and
42, respectively for receiving a guide wire, interventional
catheter, or other elongate device therethrough. The valve further
includes a duck bill structure 44 for sealing against pressure
through inlet port 40 when no catheter or other device is disposed
in the hemostasis valve. A perfusion connector 50 (best illustrated
in FIGS. 1 and 2) is mounted on the housing and communicates with
the inlet port 40 upstream of the duck bill 50. Thus, fluid access
to the lumen 24 may be maintained regardless of whether a catheter
is present in the hemostasis valve assembly 18.
[0052] In preferred aspect of the present invention, the foam
insert 38, in its uncompressed configuration (FIG. 4), will have an
open axial lumen 52, more preferably being flared open at its
proximal end 54. The lumen 52 will close, however, when the insert
38 is confined within the housing 36, as illustrated in FIG. 3. As
discussed above, the inherently large cross-sectional area of the
lumen 52 is advantageous since it permits the lumen to receive
relatively large catheters and other working devices without
stretching or damaging the foam insert. In a particularly preferred
aspect, a protective coating layer 56 will be formed over the lumen
52 surface in order to further protect against damage and loss of
material.
[0053] Referring now to FIG. 5, the flexible sheath 16 comprises an
inner lubricous liner 60 having a helical metal coil 62 wrapped
over its exterior surface. An outer plastic coating 64 is then
formed over the exterior surface of the liner as well as the metal
coil. Specific materials and methods for forming this structure are
described above.
[0054] Referring now to FIG. 6, an aortic introducer catheter 70
particularly intended for introducing devices into the brachial or
subclavian arteries, through the aortic arch, and into the
abdominal aorta is illustrated. The introducer catheter 70 is
constructed generally the same as that shown in FIGS. 1 and 2, with
identical components given identical numbers. The flexible sheath
16', however, is provided with a pair of inflation lumens 72 and
74, as illustrated in FIG. 7. The inflation lumens 72 and 74 are
connected to a first inflatable balloon 76 and a second (distal)
inflatable balloon 78. The first balloon will generally have a
diameter, when inflated, in the range from about 10 mm to 30 mm.
The purpose of the first balloon 76 will be to provide partial
occlusion of blood flow when present in the abdominal aorta. The
diameter of the second balloon 78 will typically be from 15 mm to
22 mm when inflated. The purpose of the second balloon 78 will be
to anchor the distal end of the catheter and, in a more particular
aspect, to anchor expandable grafts and other prostheses within the
aorta according to the method described hereinafter. The balloons
may be formed from a non-distendable material which allows for
precise control of the expanded diameter. Alternatively, either or
both balloons could be formed from elastomeric materials to permit
expansion over a wide range of aorta sizes. The formation of such
expandable balloons is well described in the art. Lumen connectors
80 and 82 will be provided in order to connect the balloons to
suitable inflation sources, typically pressurized contrast medium.
An end view of housing 18 is shown in FIG. 8.
[0055] Obturator 14 is illustrated in more detail in FIG. 9. Thumb
lever 30 of the actuator handle 22 is slidably mounted within the
handle and connected to the proximal end of flexible body 20.
Flexible body 20 is tubular, typically having a closed distal tip
which is preferably tapered to provide atraumatic introduction to
the desired target body location. A pull wire 86 is attached off
center to the distal tip of the flexible body 20. The pull wire
extends through a lumen 87 of the flexible body and is attached at
the proximal end of the actuator handle 22. Thus, distal motion of
the thumb lever 30 relative to the actuator handle 22 will cause
the pull wire to shorten relative to the flexible body 20. Such
shortening, in turn, will cause the distal tip to bend downward
relative to the position shown in FIG. 9. Such downward deflection
is enhanced by weakening of the opposite (upper) side of the
flexible body over the portion which is desired to be laterally
deflected. As illustrated in FIG. 9, a series of cuts 88 may be
made partially through the flexible body portion 20 in order to
provide the desired weakening.
[0056] Referring now to FIG. 10, an alternative construction for
the deflectable distal end of obturator 14 is illustrated.
Deflectable end 90 comprises a plurality of articulated links 92
which are pivotally connected. Pull wire 86 extends through the
pivotally connected links 92, and a spring member 94, typically
formed from nickel-titanium alloy or other super elastic material,
is disposed opposite to the pull wire 86. The spring provides for
straightening of the distal tip when no tension is placed on pull
wire 86. The use of pivotally attached lengths 92 is desirable
since it provides a highly flexible distal end for the
obturator.
[0057] Referring now to FIGS. 11A-11E, use of the catheter
introducer system 10 for placement of the flexible sheath 16
through the subclavian artery SC, across the aortic arch AA, and
into the abdominal aorta ABA will be described. Such procedures are
particularly useful for introducing straight or bifurcated grafts G
(FIG. 11E) for the treatment of abdominal aneurysms A.
[0058] The catheter introducer system is initially introduced
through an appropriate percutaneous access procedure so that the
distal end of the system enters the target artery. Common
percutaneous access procedures include the Seldinger technique, the
use of arterial dialators, and the surgical exposure and isolation
of the artery (commonly referred to as a "cut down" procedure). The
catheter introducer system may be inserted via the brachial artery,
the axillary artery, the subclavian artery, the femoral artery, or
the popliteal artery using any of these percutaneous or surgical
procedures. Alternatively, the introducer system can be placed into
the iliac arteries by direct surgical exposure.
[0059] FIGS. 11A-11E illustrate the case of introducing the
catheter system through the subclavian artery. The distal end can
be deflected in a desired direction, as illustrated in FIG. 11A, so
that it may pass down the subclavian artery SC toward the aortic
arch AA. After reaching the aortic arch AA, as illustrated in FIG.
11B, the catheter introducer system 10 may be rotated about its
axis and the tip deflected in the opposite direction to properly
enter into the aortic arch AA. The introducer system 10 is then
further advanced down the abdominal aorta ABA toward the aneurysm
A, as illustrated in FIG. 11C, with the tip direction being
manipulated by turning the handle and deflecting the tip in an
appropriate manner.
[0060] After reaching the region of the abdominal aorta ABA just
over the aneurysm A, the obturator 14 can be removed leaving an
access lumen in sheath 16 to the abdominal aorta. A delivery
catheter 100 can then be advanced through the sheath 16 in order to
deliver graft G, in a manner generally described in copending
applications Ser. No. 08/290,021, filed on Aug. 12, 1994, and Ser.
No. 08/255,681 filed on Jun. 8, 1994, the full disclosures of which
are incorporated herein by reference. During placement of the graft
G, the partial occlusion balloon 76 will preferably be expanded in
order to slow blood flow to the region of the aneurysm A. Such a
reduction in blood flow rate makes placement of the graft G
substantially easier. Once in place, the graft G can be anchored by
manipulating flexible sheath 16 so that distal balloon 78 enters
the end of the graft G. Expansion of balloon 78 within the graft G
helps to anchor the balloon against the aortic wall. The flexible
sheath 16 may then be withdrawn from the aorta after proper
placement of the graft G has been confirmed.
[0061] Referring now to FIGS. 12 and 13, an alternative hemostasis
valve assembly 100 which may be used in place of valve assembly 18
will be described. Hemostasis valve assembly 100 is attached to the
proximal end of flexible sheath 16 and comprises a valve body 102
having an internal cavity 104 with an expanded section 106.
Elastomeric insert 108 is received in the expanded section 106 and
has a forwardly disposed conical face 110, best seen in FIG. 13.
Conical face 110 is split along at least three lines 112 to form
three "petals" 113, but optionally could be split along four or
more lines. The split face permits passage of a catheter C, as
shown in broken line in FIG. 12. Passage of the catheter C causes
the petals defined in the face 110 to open to permit passage of the
catheter, as illustrated in broken line in FIG. 12. When the
catheter C is removed, the petals of face 110 will close, and will
remain sealed when exposed to positive pressure in the cavity 104.
The elastomeric insert 108 may further include an annular ring 114
disposed distally of the forward face 110. The annular ring
contributes to the hoop strength in the insert. In some cases, ring
114 may further provide for a sliding seal against the catheter
when passing through the insert.
[0062] Although the foregoing invention has been described in some
detail by way of illustration and example, for purposes of clarity
of understanding, it will be obvious that certain changes and
modifications may be practiced within the scope of the appended
claims.
* * * * *