U.S. patent application number 13/964015 was filed with the patent office on 2014-02-13 for stent delivery systems and associated methods.
This patent application is currently assigned to ALTURA MEDICAL, INC.. The applicant listed for this patent is Altura Medical, Inc.. Invention is credited to Andrew H. Cragg, Mahmood Dehdashtian, John Logan, Nelson Quintana, George Tsai.
Application Number | 20140046429 13/964015 |
Document ID | / |
Family ID | 50066773 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140046429 |
Kind Code |
A1 |
Cragg; Andrew H. ; et
al. |
February 13, 2014 |
STENT DELIVERY SYSTEMS AND ASSOCIATED METHODS
Abstract
Stent delivery systems and associated methods for delivering
stents are disclosed herein. In several embodiments, a handle
assembly for delivering a stent from a tubular enclosure can
include a first lead screw having a first lead thread of a first
pitch and first handedness, a second lead screw having a second
lead thread of a second pitch and second handedness different from
the first handedness, and a housing defining threads of the first
and second pitches. The first lead screw can be in mechanical
communication with the tubular enclosure, and the second lead screw
can be in mechanical communication with the stent. Upon rotation of
a portion of the housing, the housing threads can engage the lead
screws so as to induce simultaneous translations of the lead screws
in opposite directions. The simultaneous translations are
configured to deploy the stent from the tubular enclosure.
Inventors: |
Cragg; Andrew H.; (Edina,
MN) ; Logan; John; (Plymouth, MN) ; Tsai;
George; (Mission Viejo, CA) ; Quintana; Nelson;
(Temecula, CA) ; Dehdashtian; Mahmood; (Costa
Mesa, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Altura Medical, Inc. |
Palo Alto |
CA |
US |
|
|
Assignee: |
ALTURA MEDICAL, INC.
Palo Alto
CA
|
Family ID: |
50066773 |
Appl. No.: |
13/964015 |
Filed: |
August 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61681907 |
Aug 10, 2012 |
|
|
|
61799591 |
Mar 15, 2013 |
|
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Current U.S.
Class: |
623/1.12 |
Current CPC
Class: |
A61F 2/954 20130101;
A61F 2002/067 20130101; A61F 2/966 20130101; A61F 2/9517
20200501 |
Class at
Publication: |
623/1.12 |
International
Class: |
A61F 2/966 20060101
A61F002/966 |
Claims
1. A method for implanting a stent at a target area in a vessel for
treatment of an aneurysm, the method comprising: advancing, toward
the target area, a catheter comprising a tubular enclosure covering
the stent; positioning the stent proximate to the target area;
deploying the stent, wherein deploying the stent comprises--
exposing only a portion of the stent, radially expanding the
exposed portion of the stent, and completely exposing the stent
after radially expanding the partially exposed stent; allowing the
stent to anchor at the target area; and withdrawing the catheter
from the target area, wherein deploying the stent comprises
effectuating simultaneous, opposing translations of first and
second handle components such that the first handle component
longitudinally displaces the tubular enclosure in a first
direction, and the second handle component axially compresses the
stent in a second direction opposite the first direction.
2. The method of claim 1 wherein radially expanding the exposed
portion of the stent comprises: constraining one end portion of the
stent in a radially compressed state; and moving the constrained
end portion of the stent independently of and relative to a second
end portion of the stent in a compression direction, thereby
radially expanding the exposed portion of the stent.
3. The method of claim 2 wherein moving the constrained end portion
of the stent comprises pulling a constrained distal end portion of
the stent in a proximal direction.
4. The method of claim 1, further comprising forming a
substantially fluid-tight seal against a wall of the vessel with
the radially expanded, exposed portion of the stent.
5. The method of claim 4, further comprising introducing contrast
fluid through the catheter to verify the seal.
6. The method of claim 2 wherein deploying the stent further
comprises releasing the constrained end portion of the stent to
allow the end portion to expand.
7. The method of claim 2 wherein deploying the stent further
comprises: moving the constrained end portion of the stent
independently from and relative to the second end portion of the
stent in a direction opposite the compression direction, thereby
radially contracting the exposed portion of the stent; and
repositioning the stent relative to the target area.
8. The method of claim 7 wherein deploying the stent further
comprises displacing the tubular enclosure to enclose the stent
before repositioning the stent relative to the target area.
9. The method of claim 1 wherein deploying the stent further
comprises adjusting at least one of rotational orientation and
axial position of the stent after radially expanding the exposed
portion of the stent.
10. The method of claim 1 wherein deploying the stent further
comprises deploying a distal end of the stent before a proximal end
of the stent.
11. The method of claim 10 wherein deploying the stent further
comprises: longitudinally displacing the tubular enclosure in a
proximal direction to expose the stent; and axially compressing the
stent with a distally-directed force.
12. A method for implanting a stent at a target area for treatment
of an aneurysm, the method comprising: advancing, toward the target
area, a catheter comprising a tubular enclosure covering the stent;
positioning the stent proximate to the target area; deploying the
stent by effectuating simultaneous, opposing translations of first
and second handle components, wherein the first handle component
longitudinally displaces the tubular enclosure in a first
direction, and wherein, after the second handle component has been
displaced by a predetermined delay distance, the second handle
component axially compresses the stent in a second direction
opposite the first direction; allowing the stent to anchor at the
target area; and withdrawing the catheter from the target area.
13. The method of claim 12 wherein deploying the stent comprises
deploying a proximal end of the stent before a distal end of the
stent.
14. The method of claim 12 wherein deploying the stent comprises
simultaneously longitudinally displacing the tubular enclosure in a
distal direction to expose the stent and axially compressing the
stent with a proximally-directed force.
15. The method of claim 12, further comprising forming a
substantially fluid-tight seal against a wall of the vessel with
the deployed stent, and introducing contrast fluid through the
catheter to verify the seal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to each of the
following U.S. Provisional patent applications:
[0002] (A) U.S. Provisional Patent Application No. 61/681,907,
filed on Aug. 10, 2012 and entitled "HANDLE ASSEMBLIES FOR STENT
GRAFT DELIVERY SYSTEMS AND ASSOCIATED SYSTEMS AND METHODS"; and
[0003] (B) U.S. Provisional Patent Application No. 61/799,591,
filed Mar. 15, 2013 and entitled "HANDLE ASSEMBLIES FOR STENT GRAFT
DELIVERY SYSTEMS AND ASSOCIATED SYSTEMS AND METHODS."
[0004] Each of the foregoing applications is incorporated herein by
reference in its entirety.
TECHNICAL FIELD
[0005] The present technology relates to treatment of abdominal
aortic aneurysms. More particularly, the present technology relates
to handle assemblies for stent graft delivery systems and
associated systems and methods.
BACKGROUND
[0006] An aneurysm is a dilation of a blood vessel of at least 1.5
times above its normal diameter. The dilated vessel forms a bulge
known as an aneurysmal sac that can weaken vessel walls and
eventually rupture. Aneurysms are most common in the arteries at
the base of the brain (i.e., the Circle of Willis) and in the
largest artery in the human body, the aorta. The abdominal aorta,
spanning from the diaphragm to the aortoiliac bifurcation, is the
most common site for aortic aneurysms. Such abdominal aortic
aneurysms (AAAs) typically occur between the renal and iliac
arteries, and are presently one of the leading causes of death in
the United States.
[0007] The two primary treatments for AAAs are open surgical repair
and endovascular aneurysm repair (EVAR). Surgical repair typically
includes opening the dilated portion of the aorta, inserting a
synthetic tube, and closing the aneurysmal sac around the tube.
Such AAA surgical repairs are highly invasive, and are therefore
associated with significant levels of morbidity and operative
mortality. In addition, surgical repair is not a viable option for
many patients due to their physical conditions.
[0008] Minimally invasive endovascular aneurysm repair (EVAR)
treatments that implant stent grafts across aneurysmal regions of
the aorta have been developed as an alternative or improvement to
open surgery. EVAR typically includes inserting a delivery catheter
into the femoral artery, guiding the catheter to the site of the
aneurysm via X-ray visualization, and delivering a synthetic stent
graft to the AAA via the catheter. The stent graft reinforces the
weakened section of the aorta to prevent rupture of the aneurysm,
and directs the flow of blood through the stent graft away from the
aneurysmal region. Accordingly, the stent graft causes blood flow
to bypass the aneurysm and allows the aneurysm to shrink over
time.
[0009] Most stent and stent graft systems for cardiovascular
applications (e.g., coronary, aortic, peripheral) utilize
self-expanding designs that expand and contract predominantly in
the radial dimension. However, other system include braided stent
grafts that are delivered in a radially compressed, elongated
state. Upon delivery from a delivery catheter, the stent graft will
radially expand and elastically shorten into its free state. In
other words, the effective length of the stent graft changes as its
diameter is forced smaller or larger. For example, a stent graft
having a shallower, denser helix angle will result in a longer
constrained length. Once the stent graft is removed from a
constraining catheter, it can elastically return to its natural,
free length.
[0010] Delivering a stent graft to an artery requires accurate and
precise positioning of the stent graft relative to a target
location in the destination artery. For example, a misplaced stent
graft can block flow to a branching artery. Some stent graft
delivery systems utilize one or more markers (e.g., radiopaque
markers) to establish the alignment of the stent graft relative to
the artery wall. However, the location of the radiopaque markers on
the stent graft can move relative to an initial marker position
because of the change in the stent graft's effective length upon
deployment, as described above. Accordingly, after deployment of a
stent graft, the stent graft (e.g., its proximal or distal edge)
may miss the target point in the artery. Therefore, there are
numerous challenges associated with the accurate positioning of
stent grafts that change dimensions in both the radial and
longitudinal directions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A is an isometric view of a stent graft delivery
system configured in accordance with an embodiment of the
technology.
[0012] FIGS. 1B and 1C are functional schematic diagrams of a
portion of a handle assembly system configured in accordance with
embodiments of the technology.
[0013] FIG. 2A is an isometric view of a handle assembly configured
in accordance with an embodiment of the technology.
[0014] FIGS. 2B and 2C are side views of a delivery catheter of a
stent graft delivery system configured in accordance with an
embodiment of the technology.
[0015] FIGS. 2D and 2E are side views of collets of a stent graft
delivery system configured in accordance with an embodiment of the
technology.
[0016] FIGS. 3A-3C are side views of a delivery catheter of a stent
graft delivery system configured in accordance with an embodiment
of the technology.
[0017] FIGS. 4A-4E are front and side views of collets of a stent
graft delivery system configured in accordance with various
embodiments of the technology.
[0018] FIGS. 5A and 5B are partial side views of a handle assembly
and a housing, respectively, configured in accordance with various
embodiments of the technology.
[0019] FIG. 6A is a partial cut-away view of a handle assembly
configured in accordance with an embodiment of the technology.
[0020] FIGS. 6B-6D are enlarged partial cut-away views of portions
of the handle assembly of FIG. 6A.
[0021] FIG. 6E is an isometric view of a portion of the handle
assembly of FIG. 6A.
[0022] FIG. 7 is an enlarged partial cut-away view of a distal
portion of the handle assembly configured in accordance with an
embodiment of the technology.
[0023] FIG. 8A is an isometric view of a handle assembly configured
in accordance with another embodiment of the technology.
[0024] FIG. 8B is an enlarged, partially translucent isometric view
of a portion of the handle assembly of FIG. 8A.
[0025] FIG. 9 is a partial cut-away isometric view of a handle
assembly configured in accordance with another embodiment of the
technology.
[0026] FIGS. 10A and 10B are side and partial cut-away views,
respectively, of a handle assembly configured in accordance with
another embodiment of the technology.
[0027] FIG. 11A is an isometric view of a stent graft delivery
system configured in accordance with another embodiment of the
technology.
[0028] FIGS. 11B and 11C are side views of a delivery catheter of
the stent graft delivery system of FIG. 11A configured in
accordance with an embodiment of the technology.
[0029] FIG. 11D is a side view of a collet of the a stent graft
delivery system of FIG. 11A configured in accordance with an
embodiment of the technology.
[0030] FIG. 12A is a partial cut-away view of a handle assembly
configured in accordance with an embodiment of the technology.
[0031] FIGS. 12B-12D are enlarged partial cut-away views of
portions of the handle assembly of FIG. 12A.
[0032] FIG. 13 is a partially translucent isometric view of a
portion of a handle assembly configured in accordance with another
embodiment of the technology.
[0033] FIG. 14 is a partially translucent isometric view of a
portion of a handle assembly configured in accordance with another
embodiment of the technology.
[0034] FIG. 15A is a partial isometric view of a portion of a
handle assembly configured in accordance with an embodiment of the
technology.
[0035] FIG. 15B is an enlarged view of a portion of the handle
assembly of FIG. 15A.
[0036] FIG. 15C is a partially translucent side view of a portion
of the handle assembly of FIG. 15A.
[0037] FIGS. 16A and 16B are partially schematic representations of
a method of stent graft delivery in accordance with an embodiment
of the technology.
[0038] FIG. 17 is a partially schematic representation of a method
of stent graft delivery in accordance with an embodiment of the
technology.
[0039] FIGS. 18A-18E illustrate a stent delivery method in
accordance with an embodiment of the technology.
[0040] FIGS. 19A-19C illustrate a stent delivery method in
accordance with another embodiment of the technology.
DETAILED DESCRIPTION
[0041] The present technology is directed toward handle assemblies
for stent delivery systems and associated systems and methods.
Certain specific details are set forth in the following description
and in FIGS. 1A-19C to provide a thorough understanding of various
embodiments of the technology. For example, many embodiments are
described below with respect to the delivery of stent grafts that
at least partially repair AAAs. In other applications and other
embodiments, however, the technology can be used to repair
aneurysms in other portions of the vasculature. Furthermore, the
technology can be used to deliver a stent for any suitable purpose
in any suitable environment. Other details describing well-known
structures and systems often associated with stent grafts and
associated delivery devices and procedures have not been set forth
in the following disclosure to avoid unnecessarily obscuring the
description of the various embodiments of the technology. Many of
the details, dimensions, angles, and other features shown in the
Figures are merely illustrative of certain embodiments of the
technology. For example, dimensions shown in the Figures are
representative of particular embodiments, and other embodiments can
have different dimensions. A person of ordinary skill in the art,
therefore, will accordingly understand that the technology may have
other embodiments with additional elements, or the technology may
have other embodiments without several of the features shown and
described below with reference to FIGS. 1A-19C.
[0042] In this application, the terms "distal" and "proximal" can
reference a relative position of the portions of an implantable
stent graft device and/or a delivery device with reference to an
operator. Proximal refers to a position closer to the operator of
the device, and distal refers to a position that is more distant
from the operator of the device. Also, for purposes of this
disclosure, the term "helix angle" refers to an angle between any
helix and a longitudinal axis of the stent graft.
Selected Embodiments of Stent Delivery Systems
[0043] As shown in FIGS. 1A-1C, various embodiments of a stent
delivery system 100 can include a delivery catheter 120 having a
shaft or tubular enclosure 124 on a distal end portion of the
catheter 120, a braided stent 110 (FIGS. 1B and 1C) constrained
within the tubular enclosure 124, and a handle assembly 150 at a
proximal end portion of the delivery catheter 120. Various
embodiments of the technology may be used to deliver the braided
110 stent to a target area within a body lumen of a human. For
example, one embodiment of the stent delivery system 100 can be
configured to deploy a stent at a target location in an aorta such
that at least a portion of the stent is superior to an aortic
aneurysm. As another example, another embodiment of the stent
delivery system 100 can be configured to deploy a stent at a target
location in an iliac artery such that at least a portion of the
stent is inferior to an aortic aneurysm. Further embodiments of the
technology may be used to deliver a stent to any suitable target
area.
[0044] 1.1 Selected Embodiments of Delivery Catheters and
Stents
[0045] The delivery catheter 120 of various embodiments can include
a distal end portion insertable into a body lumen within a human
and navigable toward a target area, and nested components
configured to mechanically communicate actions of the handle
assembly 150 to distal end portion of the delivery catheter 120.
The stent 110 (FIGS. 1B and 1C) can be constrained in a radially
compressed state at the distal end portion of the delivery catheter
120. In some embodiments, the delivery catheter 120 has a diameter
of approximately 14 Fr, but in other embodiments the delivery
catheter 120 can have a greater diameter or a smaller diameter,
such as 10 Fr or 8 Fr.
Selected Embodiments of Distal End Portions of Delivery
Catheters
[0046] FIGS. 2A-2E illustrate an embodiment of a stent delivery
system 200 configured in accordance with another embodiment of the
technology, and FIGS. 3A-3C illustrate portions of a delivery
catheter 220 of the stent delivery system 200 of FIGS. 2A-2C. As
shown in FIG. 2A, the stent delivery system 200 can include the
delivery catheter 220 and handle assembly 250 operably coupled to
the delivery catheter 220. As shown in FIGS. 2B, 2C, and 3A-3C, the
distal end portion of delivery catheter 220 includes a distal top
cap 222 and an outer sheath 224 that engage a stent 210. More
specifically, the distal top cap 222 covers and constrains at least
a distal end portion 210d of the stent 210 in a radially compressed
configuration, and the outer sheath 224 covers and constrains at
least a proximal end portion 210p of the stent 210 in a radially
compressed configuration. In some embodiments, the top cap 222 and
outer sheath 224 can overlap or meet edge-to-edge so as to entirely
cover the stent 210, though in other embodiments the top cap 222
and outer sheath 224 can leave a medial portion of the stent 210
uncovered. The top cap 222 can have a tapered distal end to help
navigate the catheter through a patient's vasculature, and/or a
radiused proximal edge that may reduce snagging or catching on
vasculature or other features during catheter retraction after
stent deployment.
[0047] FIGS. 11A-12D show an embodiment of a delivery system 400
configured in accordance with another embodiment of the technology.
Similar to the stent delivery system 200 of FIGS. 2A-2E, the stent
delivery system 400 of FIGS. 11A-12D can include a delivery
catheter 420 and handle assembly 450 operably coupled to the
delivery catheter 420. As shown in FIGS. 11B and 11C, the distal
end portion of the delivery catheter 420 can include a distal top
cap 424 having a tubular enclosure that covers and constrains the
entirety of the stent 410 in a radially compressed configuration.
Removing the top cap 424 in a distal direction can expose the stent
410. Similar to the top cap 222 shown in FIGS. 2B and 2C, the top
cap 424 can have a tapered distal end and/or radiused proximal
edge.
[0048] Other embodiments of delivery catheters can have distal end
portions that include an outer sheath that covers and constrains
the entirety of the stent in a radially compressed configuration
such that retraction of the outer sheath in a proximal direction
exposes the stent. Furthermore, in some embodiments, the top cap
222, 424 and/or the outer sheath can include radiopaque markers
that provide visual aids for device positioning during deployment
procedures. Such radiopaque markers can be helical, circumferential
rings, and/or have any other suitable form. Additionally, in some
embodiments, the top cap 222, 424 and/or the outer sheath can
include structural reinforcements, such as filaments, to discourage
deformation in tension or compression. For example,
axially-oriented filaments can be interwoven or otherwise coupled
to the top cap 222, 424 or outer sheath such that the top cap 222,
424 or outer sheath is stretch-resistant and facilitates smooth,
predictable actuation by the various nested components described
below. As another example, the top cap 222, 424 and/or outer sheath
can include other reinforcements to increase column strength and
discourage buckling during actuation by the various nested
components.
Selected Embodiments of Stents and Collets
[0049] As shown in, for example, FIG. 2B, the stent 210 can be
disposed at the distal end portion of the delivery catheter 220.
The stent 210 can be a bare stent or a stent graft, such as those
described in U.S. Application Patent Publication No. 2011/0130824,
which is incorporated herein by reference in its entirety. In other
embodiments, the stent 210 can be any suitable braided stent or
other self-expanding stent. As described above, the stent 210 can
be constrained in a radially compressed configuration by the top
cap 222 and/or an outer sheath. Additionally, as shown in FIG. 2C,
prior to stent deployment, the stent (not shown) can be axially
constrained at the distal end portion of the delivery catheter 220
with one or more collets 226, 228 coupled to one or more nested
components of the delivery catheter 220.
[0050] FIGS. 4A-4E are front and side views of various collets 226,
228 that are configured to couple stents to the distal end portion
of the delivery catheter 220 (FIG. 2C). Generally, the collets 226
and 228 can each include a fluted portion with circumferentially
distributed prongs 227, each of which engages an opening on a stent
and constrains the longitudinal position of the stent at the point
of engagement. Each prong 227 can have a radius of curvature that
matches that of the stent it is configured to engage and a height
that exceeds the height of the stent wire by a suitable amount so
as to help ensure engagement with the stent. For example, the
prongs 227 may have a height about 1.5 times the height of the
stent wire. In other embodiments, the prongs 227 may have other
suitable heights. The number, arrangement, and particular prong
profiles can be suitably tailored to the specific application. For
example, the collets 226 and 228 can include an angled tip, a
5-point angled tip, a rounded tip that reduces or eliminates
friction or undesirable catching on the stent wire, and/or a spring
229 (FIG. 4E) that assists in launching the stent wire into radial
expansion during stent deployment.
[0051] Delivery systems in accordance with the present technology
can include a trailing or proximal collet 226 (FIGS. 4D and 4E)
coupled to a proximal end portion of a stent, a leading or distal
collet 228 (FIGS. 4A-4C) coupled to a distal end portion of the
stent, or both the trailing collet 226 and the leading collet 228.
In other embodiments, individual collets can be coupled to other
suitable portions of a stent (e.g., a medial portion of a stent).
As shown in FIGS. 11B and 11C, in further embodiments one or more
end portions of a stent can be coupled to the distal end portion of
the delivery catheter 420 with a smooth, prongless docking tip
426.
Selected Embodiments of Nested Components
[0052] Nested components along the delivery catheters 220 and 420
described above can be configured to mechanically control aspects
of the distal end portion of the delivery catheter. In various
embodiments, each of the nested components can be configured to
longitudinally move independently of the other nested components,
whereas in other embodiments two or more nested components can
temporarily or permanently be locked together to permit movement in
tandem. At least portions of the nested components outside of a
handle assembly (e.g., the handle assemblies 250 and 450) can be
sufficiently flexible to permit navigation and advancement through
potentially tortuous paths through a blood vessel, though the
degree of flexibility can vary depending on the application (e.g.,
the location of the target site and/or the path to the target
site). The nested components can include a plurality of tubes
and/or wires that are configured to push and/or pull various
components of the distal end portion of the delivery catheter. As a
person of ordinary skill in the art would appreciate, although the
components of the delivery catheters 220 and 420 are described
herein as "nested", in other embodiments the delivery catheters 220
and 420 can include similar operative components arranged laterally
offset from one another.
[0053] FIG. 2C shows an embodiment of the delivery catheter 220 in
which the nested components include a tip tube 230, an inner shaft
232, and a dilator 236, although in other embodiments the delivery
catheter 220 can include any suitable number of tubes and/or
shafts. As shown in FIGS. 6A and 6C, in various embodiments, the
nested components can further include one or more stiffeners 234
disposed within and/or around other nested components. The
stiffener 234 can, for example, axially reinforce a portion of a
pushing component (e.g., the inner shaft 232) to increase the
column strength of the pushing component. The stiffener 234 can be
made of stainless steel or any other suitably rigid material. In
the embodiment shown in FIGS. 2C and 6A, the tip tube 230 is
disposed within the inner shaft 232, and the inner shaft 232 is
disposed within the dilator 236, with the stiffener 234 (FIG. 6A)
surrounding and reinforcing portions of the tip tube 230 and the
inner shaft 232 within the handle assembly 250.
[0054] In the embodiment shown in FIGS. 2B and 2C, the tip tube 230
is operatively connected to the top cap 222 such that proximal and
distal movement of the tip tube 230 corresponds to longitudinal
movement of the top cap 222. For example, sufficient distal
movement of the tip tube 230 can cause the top cap 222 to move
distally enough to release the distal end portion 210d of the stent
210, thereby allowing the distal end portion 210d of the stent 210
to self-expand. In some embodiments, the tip tube 230 can be made
of stainless steel, and in other embodiments the tip tube 230 can
additionally or alternatively include any other suitable materials.
Furthermore, the tube 230 can include suitable structural
reinforcing features, such as a stainless steel braid.
[0055] In the embodiment shown in FIGS. 2A-2E, the inner shaft 232
is operatively connected to the leading collet 228 engaged with the
distal end portion 210d of the stent 210 such that proximal and
distal movement of the inner shaft 232 corresponds to longitudinal
movement of the leading collet 228 and distal end portion 210d of
the stent 210. In other embodiments, the inner shaft 232 can be in
mechanical communication with the distal end portion 210d of the
stent 210 in other suitable manners. The inner shaft 232 can
permit, within its lumen, telescopic movement of the tip tube 230,
thereby allowing longitudinal movement of the top cap 222 relative
to the leading collet 228. The inner shaft 232 can be a tube made
of polyimide and/or other suitable materials.
[0056] In the embodiment shown in FIG. 2C, the dilator 236 is
operatively connected to the trailing collet 226, which is in turn
engaged with the proximal end portion 210p of the stent 210 such
that proximal and distal movement of the dilator 236 corresponds to
longitudinal movement of the trailing collet 226 and the proximal
end portion 210p of the stent 210. The dilator 236 can permit,
within its lumen, telescopic movement of the tip tube 230 and the
inner shaft 232. In turn, the outer sheath 224 can permit, within
its lumen, the telescopic movement of the dilator 236. Accordingly,
the top cap 222, the leading collet 228, and the trailing collet
226 may move relative to one another corresponding to relative
movement of the tip tube 230, the inner shaft 232, and the dilator
236, respectively. The dilator 236 can be made from nylon and/or
various other suitable materials.
[0057] In certain embodiments, the nested components described
above with respect to FIGS. 2C, 6A, and 6C can be used to deliver a
stent to an aorta before an aneurysm. In other embodiments, the
nested components can be used to deliver stents to other blood
vessels, such as the iliac arteries.
[0058] FIGS. 11A-11C show another embodiment of the delivery
catheter 420 in which the nested components include a tip tube 430,
an inner shaft 432, and a dilator 436, although in other
embodiments the delivery catheter 420 can include any suitable
number of tubes and/or shafts. As shown in FIGS. 12A and 12D, the
nested components can additionally include one or more stiffeners
(identified individually as a first stiffener 434a and a second
stiffener 434b, and referred to collectively as stiffeners 434)
disposed within and/or around other nested components. Similar to
the embodiment of FIG. 6A, the stiffeners 434 can, for example,
reinforce a pushing component for increased column strength of that
pushing component. The stiffeners 434 can be made of stainless
steel or any other suitably rigid material. In the embodiment shown
in FIG. 11C, a portion of the tip tube 430 is disposed within the
inner shaft 432, and another portion of the tip tube 430 is
disposed within the dilator 436. As shown in FIG. 12A, the first
and second stiffeners 434a and 434b can surround and reinforce
another portion of the tip tube 430 within the handle assembly 450.
In other embodiments, however, the nested components can be
configured in any suitable arrangement. Furthermore, some or all of
the nested components can be replaced or supplemented with wires or
other suitable control mechanisms.
[0059] In the embodiment of FIGS. 11A-12B, the tip tube 430 is
operatively connected to the top cap 424 such that the proximal and
distal movement of the tip tube 430 corresponds to longitudinal
movement of the top cap 424. In particular, sufficient distal
movement of the tip tube 430 can cause the top cap 424 to move
distally enough to release the stent 410, thereby allowing the
stent to self-expand. The tip tube 430 can be made of stainless
steel and/or other suitable materials. Furthermore, the tube 430
can include suitable structural reinforcing features, such as a
stainless steel braid.
[0060] As further shown in the embodiment of FIGS. 11A-12B, the
inner shaft 432 is operatively connected to the leading collet 428,
which is in turn engaged with the distal end portion 410d of the
stent 410 such that proximal and distal movement of the inner shaft
432 corresponds to longitudinal movement of the leading collet 428
and the distal end portion 410d of the stent 410. In other
embodiments, the inner shaft 432 can be in mechanical communication
with the distal end portion 410d of the stent 410 in any suitable
manner. Within its lumen, the inner shaft 432 can permit telescopic
movement of the tip tube 430. The inner shaft 432 can be a tube
made of polyimide and/or other suitable materials.
[0061] As shown in FIG. 11C, the dilator 436 can be coupled to a
docking tip 426, which engages with the proximal end portion 410p
of the stent 410 at the distal end portion of the delivery catheter
420. Within its lumen, the dilator 436 can permit telescopic
movement of the inner shaft 432 and the tip tube 430. The dilator
436 is made of nylon and/or other suitable materials.
[0062] In certain embodiments, the nested components described
above with respect to FIGS. 11A-12B can be used to deliver a stent
to an iliac artery after an aneurysm. In other embodiments, the
nested components can be used to deliver stents to other blood
vessels, such as the aorta.
[0063] Though the above embodiments are described in detail with
particular arrangements of nested components, in other embodiments
the nested components can be configured in any suitable
arrangement. Additionally, other embodiments can include any
suitable number of nested push/pull components. Furthermore, some
or all of the nested components can be replaced or supplemented
with wires or other suitable control mechanisms.
[0064] 1.2 Selected Embodiments of Handle Assemblies
[0065] Various embodiments of handle assemblies can be used in
conjunction with other aspects of the stent delivery systems 200
and 400 as described above, but can additionally or alternatively
be used to deploy any suitable stent or stent graft constrained
within a tubular enclosure of a delivery catheter in a radially
compressed, elongated state. In particular, as described in further
detail below and demonstrated in the functional diagrams of FIGS.
1B and 1C, the handle assembly 150 of FIG. 1A can incorporate
various mechanisms to effectuate the opposing displacement of an
uncovering component 160 and a position compensating component 162
at a predetermined payout ratio, which deploys the stent 110 in a
controlled manner. The uncovering component or element 160 can also
configured to expose the stent 110 from the tubular enclosure 124
and allow the exposed portion of stent 110 to radially self-expand.
The position compensating component 162 provides an axially
compressive force on the stent 110 that counteracts the
longitudinal displacement otherwise resulting from changing stent
length as the stent 110 radially expands. Generally speaking, as
shown in FIG. 1B, the position compensating component 162 can
actuate in a distal direction while the uncovering element 160 can
actuate in a proximal direction. Alternatively, as shown in FIG.
1C, the positioning compensating component 162 can actuate in a
proximal direction while the uncovering component 160 can actuate
in a distal direction.
[0066] The synchronized motion of the uncovering component 160 and
the position compensating component 162 can control the axial
position of the exposed portion of the stent 110. When the ratio of
the components' movements is matched to or corresponds to the helix
angle of the stent 110, the position of the deployed stent 110 can
be maintained relative to a particular destination target location.
Although in many applications it is desirable that at least one end
of the stent 110 remain stationary during deployment, in some
alternative applications it might be desirable to modify the
predetermined payout ratio so that the exposed portion of the stent
110 moves in a controlled manner at a predetermined rate.
Selected Embodiments of Lead Screws
[0067] FIGS. 5A-12D illustrate various handle assemblies with lead
screws configured in accordance with embodiments of the technology.
For instance, as shown in FIGS. 5A and 5B, various embodiments of a
handle assembly for delivering a stent from a tubular enclosure
(e.g., the tubular enclosure 124 of FIG. 1A) can include a first
lead screw 260, a second lead screw 262, and a housing 270
surrounding at least a portion of each of the first and second lead
screws 260 and 262. The first lead screw 260 has a lead thread of a
first pitch and a first handedness (i.e., the lead screw has a
right-handed or left-handed thread), and is coupled to the tubular
enclosure. The second lead screw 262 has a lead thread of a second
pitch and a second handedness different from the first handedness,
and is coupled to the stent. The housing 270 surrounds at least a
portion of each of the first and second lead screws 260 and 262,
and defines two housing threads, including a first housing thread
276 with the same pitch and handedness as the first lead screw 260
and a second housing thread 278 with the same pitch and handedness
as the second lead screw 262. The housing 270 and lead screws 260,
262 can be configured to cooperate such that upon rotation of at
least a portion of the housing around a longitudinal axis, the
first housing thread 276 engages the first lead screw 260 and
second housing thread 278 engages the second lead screw 262. The
engagements between the housing threads 276, 278 and the lead
screws 260, 262 induce simultaneous translations of the first and
second lead screws 260 and 262 in opposite directions along a
longitudinal axis A-A (FIG. 5A) of the housing 270, and the
simultaneous translations deploy the stent from the tubular
enclosure. In particular, translation of the first lead screw 260
can cause the tubular enclosure to translate to expose the stent
and allow the exposed portion of the stent to radially self-expand.
At the same time, translation of the second lead screw 262 can
apply an axially compressive force to the stent that substantially
avoids or counterbalances longitudinal displacement of the end of
the stent that is initially exposed.
[0068] As shown in FIGS. 5A-12D, various embodiments of handle
assemblies can include first and second lead screws that have
different handedness such that their rotation in the same direction
induces their movement in opposite directions. For example, the
first lead screw can have a right-handed thread, and the second
lead screw can have a left-handed thread. Alternatively, the first
lead screw can have a left-handed thread, and the second lead screw
can have a right-handed thread. Since the first and second lead
screws have threads of opposite handedness, their concurrent
rotation in the same direction will induce their translations in
opposite directions. Additionally, the threads of lead screws can
be external threads (e.g., as shown in FIG. 5A) or internal
threads.
[0069] Furthermore, as shown in FIGS. 5A-12D, the first and second
lead screws in various embodiments of the handle assembly can have
different thread pitches such that their concurrent rotation
induces their movement at different rates of travel. As shown in
FIG. 5A, for example, the first lead screw 260, which is in
mechanical communication with the tubular enclosure, can have a
relatively coarse thread pitch, and the second lead screw 262,
which is in mechanical communication with the proximal or distal
end portion of the stent, can have a relatively fine thread pitch.
Alternatively, the first lead screw 260 can have a relatively fine
thread pitch, while the second lead screw 262 can have a relatively
coarse thread pitch, or the first and second lead screws 260 and
262 can have substantially equal thread pitches. The ratio of
thread pitches corresponds to a predetermined payout ratio of the
first and second lead screws 260 and 262 and, in various
embodiments, can correspond to the braid angle of the stent. In
certain embodiments, for example, the ratio of the coarse thread
(e.g., on the first lead screw 260) to the fine thread (e.g., on
the second lead screw 262) is approximately 1.5:1. Payout ratios
ranging from about 1:1 to about 2:1 have also been shown to provide
acceptable stent deployment. In other embodiments, the payout ratio
of the first and second lead screws 260 and 262 can differ
depending on the application. For example, both the first and
second lead screws 260 and 262 can have relatively fine thread
pitches that may allow for precise deployment, since a fine lead
screw axially translates less distance per rotation than a coarse
lead screw would for the same rotation. In this manner, the
specific pitches and/or the ratio of the pitches can be selected to
achieve a particular degree of mechanical advantage, a particular
speed and precision of stent deployment, and/or a selected
predetermined payout ratio.
[0070] As shown in FIGS. 5A-12D, the first and second lead screws
can have cross-sections that enable them to longitudinally overlap
and slide adjacent to each other along the longitudinal axis of the
handle. As shown in FIG. 5A, for example, at least the threaded
lengths of the lead screws 260, 262 are "half" lead screws, each
having an approximately semi-circular cross-section and arranged so
that the lead screws 260, 262 are concentric. When mated
longitudinally, the semi-circular cross-sections cooperate to
define a lumen through which various push/pull tubes, wires, and/or
other suitable mechanisms for stent deployment can travel and
extend distally into the delivery catheter. In other embodiments,
the first and second lead screws 260 and 262 can have other
complementary arcuate cross-sections, and/or other suitable
cross-sectional shapes.
[0071] In various embodiments, the lead screws 260 and 262 can have
an initial offset arrangement prior to stent deployment such that
the first and second lead screws 260 and 262 have no longitudinal
overlap within the housing 270 or overlap for only a portion of the
length of the lead screws 260, 262. Upon rotation of the housing
270, the lead screws 260, 262 can translate relative to one another
to increase their longitudinal overlap. In certain embodiments, for
example, the lead screws 260, 262 in the initial offset arrangement
have an initial overlap area of approximately five to nine
centimeters (e.g., seven centimeters). In operation, the handle
assembly can be configured such that rotation of the housing 270
during the course of stent deployment induces the first lead screw
260 (and movement of the tubular enclosure coupled thereto) to
axially translate a distance of approximately 15 to 25 centimeters
relative to its position in the initial offset arrangement.
Additionally, the handle assembly can be configured such that
rotation of the housing during the course of stent deployment
induces the second lead screw 262 (and movement of the associated
end of the stent) to axially translate a distance of approximately
5 to 15 centimeters. For example, in one embodiment the second lead
screw 262, which is in mechanical communication with an end of the
stent, is configured to shorten the length of the stent (relative
to the length of the stent in its elongated radially compressed
configuration) by approximately 25% to 75% (e.g., approximately
50%). In other embodiments, the degree of change in the stent
length pre-deployment to post-deployment can differ depending on
the specific application. In other embodiments, rotation of the
housing 270 during stent deployment can cause the first lead screw
262 to axially translate more than 25 centimeters or less than 15
centimeters from its initial position, and cause the second lead
screw 262 to axially translate more than 15 centimeters or less
than 5 centimeters from its initial position.
[0072] In various embodiments, the first and second lead screws 260
and 262 can define additional mating features to facilitate mutual
alignment. For example, one lead screw (e.g., the first lead screw
260) can define a longitudinal key or spline that slidingly engages
with a longitudinal slot on the other lead screw (e.g., the second
lead screw 262) such that the lead screws maintain longitudinal
alignment with each other as the lead screws longitudinally
translate past one another. In other embodiments, one or both lead
screws can include other suitable alignment features.
[0073] The first and second lead screws 260 and 262 can be made of
injection molded plastic of suitable column strength and overall
torsional rigidity to bear axial loads and/or torsional loads
during stent deployment. In other embodiments, the lead screws 260,
262 can additionally or alternatively include other suitable
materials that are milled, turned, casted, and/or formed in any
suitable manufacturing process to create the threads and other
associated features of the lead screws 260, 262. The lead screws
260, 262 can additionally or alternatively meet predetermined load
requirements by including particular thread types (e.g., acme
threads or other trapezoidal thread forms) and/or material
reinforcements. In some embodiments, the plastic material is of a
formulation including a lubricant for low-friction thread
engagement, such as LUBRILOY.RTM. D2000. Furthermore, suitable
external lubricants can additionally or alternatively be applied to
the lead screws 260, 262 to help ensure smooth engagement of the
threads.
[0074] As shown in FIGS. 5A-12D, in various embodiments of the
handle assembly, the housing can include a stationary portion and
rotatable shaft portion. As shown in FIG. 5A, for example, the
housing 270 can include a first or rotatable shaft portion 252a and
a second or stationary portion 252b coupled to one another and
secured by a locking collar 254. Though the first shaft portion
252a is referred to herein as the "rotatable shaft portion 252a" of
the housing 270 and the second shaft portion 252b is referred to as
the "stationary shaft portion 252b", it should be understood that
in other embodiments either the first or second shaft portion 252a
or 252b can be rotated in an absolute frame of reference, and/or
rotated relative to the other shaft portion 252a, 252b. As shown in
FIG. 5B, the rotatable shaft portion 252a can define housing the
first and second housing threads 276 and 278 that are configured to
threadingly engage with corresponding threads on lead screws 260
and 262. Accordingly, rotation of the rotatable shaft portion 252a
relative to the stationary shaft portion 252b can cause the first
and second threads 276 and 278 to engage the corresponding threads
on lead screws 260 and 262, and therefore cause the first and
second lead screws 260 and 262 to axially translate. In other
embodiments, any suitable portion of the housing 270 can define the
threads 276 and 278. Similarly, FIG. 11A illustrates another
embodiment in which the housing 470 includes a first or rotatable
shaft portion 452a and a second or stationary portion 452b that are
coupled to one another and secured by a locking collar 454.
[0075] In some embodiments, as shown in FIG. 5B, the housing 270
defines internal threads configured to engage with the externally
threaded lead screws 260, 262 (FIG. 5A). In other embodiments, the
housing 270 can define external threads configured to engage with
internally threaded lead screws. In some embodiments, as shown in
FIGS. 5A and 5B, the stationary shaft portion 252b (or another
suitable part of housing 270) can include one or more keyway
splines 279 (FIG. 5B), and/or any other suitable key mechanism.
Each keyway spline 279 can engage a respective axial groove 269
(FIG. 5A) in one of the lead screws 260, 262 to prevent rotation of
the lead screws 260, 262 when the rotatable shaft portion 252a
rotates, thereby substantially constraining the lead screws 260,
262 to axial translation only.
[0076] The housing 270 can include shell pieces that mate and
couple to one another to form the stationary shaft portion 252b and
the rotatable shaft portion 252a. The shell pieces can define keys
and/or other interlocking or alignment features to properly mate
and form a volume or enclosure that is configured to house or
otherwise contain the first and second lead screws 260 and 262
and/or other catheter components. The shell pieces can be snap fit
together, attached by screws and/or other mechanical fasteners,
and/or otherwise joined. Similar to the first and second lead
screws 260 and 262, the portions of the housing 270 can be composed
of a suitable rigid plastic formed by injection molding. In other
embodiments, the housing 270 can additionally or alternatively
include any other suitable materials and/or be formed by casting,
turning, milling, and/or any other suitable manufacturing process.
In various embodiments, the housing 270 can be made of a lubricious
plastic material and/or coated with external lubricant to
facilitate smooth thread engagement with the lead screws 260, 262
and relative rotation between the rotating and stationary shaft
portions 252a and 252b of the housing 270.
[0077] FIGS. 6A-6E show an embodiment of the handle assembly 250
with the first and second lead screws 260 and 262. In this
embodiment, the handle assembly 250 is configured to deploy, from
the outer sheath 224 or other tubular enclosure, a distal end of
the stent (not shown) before the proximal end of the stent during
stent delivery. By deploying the distal end of the stent first and
maintaining the axial position of the exposed distal end of the
stent, the handle assembly 250 enables accurate and precise
positioning of the distal end of the stent. This functionality can
be useful for applications where accurate and precise placement of
the distal end of the stent is clinically necessary. For example,
then the aorta is accessed through the femoral artery (as is
typical of EVAR procedures for AAA repair), this embodiment of
handle assembly 250 can be used to deploy a stent graft in a known
region of healthy aortic tissue that is superior to an aortic
aneurysm but inferior to a renal artery. Precise superior
positioning of the distal end of the stent is expected to increase
(e.g., maximize) coverage of and sealing to healthy aortic neck
tissue without blocking blood flow into the renal artery. In other
embodiments, the handle assembly 250 may be used in various other
applications that require or benefit from accurate placement of a
distal end of the stent (with respect to the handle operator)
1.
[0078] In the embodiment shown in FIGS. 6A-6E, the first lead screw
260 is directly or indirectly coupled to a tubular enclosure that
can translate in a proximal direction to expose the stent. For
example, as shown in FIGS. 6A and 6B, the first lead screw 260 can
be coupled to outer sheath 224 of the delivery catheter such that
translation of the first lead screw 260 actuates corresponding
translation of the outer sheath 224. In certain embodiments, the
first lead screw 260 can be coupled to a distal coupler 242, which
is in turn coupled to the outer sheath 224 such that proximal and
distal movement of the first lead screw 260 corresponds to proximal
and distal movement of the outer sheath 224. For instance,
sufficient proximal movement of the first lead screw 260 and distal
coupler 242 will cause the outer sheath 224 to move proximally
enough to expose the distal portion of the stent, thereby allowing
the exposed portion of the stent to expand. Alternatively, the
coupling between the first lead screw 260 and the outer sheath 224
can include any suitable mechanical communication between the first
lead screw 260 and a tubular enclosure housing a stent. For
example, the first lead screw 260 can be coupled directly to the
tubular enclosure, coupled to a push or pull tube, a wire, and/or
another suitable mechanism that is in turn coupled to the tubular
enclosure. The first lead screw 260 can be coupled to the distal
coupler 242 and/or other coupling epoxy, snap fit coupler designs,
and/or any suitable mechanical fasteners. However, the coupling can
additionally or alternatively include any suitable kind of coupling
that effectuates movement of the tubular enclosure.
[0079] As shown in FIGS. 6A-6E, the second lead screw 262 can be
directly or indirectly coupled to a proximal end of the stent (not
shown) such that translation of the second lead screw 262 actuates
corresponding translation of the proximal end of the stent. As
shown in FIG. 6D, the second lead screw 262 is configurable to be
mechanical communication with a proximal coupler 240 that is
coupled to dilator 236, which is in turn coupled to the proximal
end of the stent (e.g., as shown in FIG. 2C). For example, the
second lead screw 262 can have a coupler engagement surface 264 in
the same longitudinal path as the proximal coupler 240 such that
when second lead screw 262 moves a sufficient distance in a distal
direction, the coupler engagement surface 264 will abut the
proximal coupler 240. After this engagement occurs, distal movement
of the second lead screw 262 will cause corresponding distal
advancement of the proximal coupler 240, the dilator 236, and the
proximal end of the stent. Alternatively, the coupling between the
second lead screw 262 and the proximal end of the stent (or other
suitable stent portion) can include any suitable mechanical
communication, such as those described above regarding the coupling
between the first lead screw 260 and the outer sheath.
[0080] The handle assembly 250 can further include a stent
compressor in mechanical communication with a first portion (e.g.,
a distal portion) of the stent and independently movable relative
to a second portion of the stent such that movement of the stent
compressor is independent of the lead screws 260, 262 and
corresponds to axial compression and radial expansion of the stent.
In the embodiment illustrated in FIG. 6E, for example, the stent
compressor is defined by an axial compression slider 280 that is in
mechanical communication with the distal end of the stent
independent of the first and second lead screws 260 and 262. In
other embodiments, the handle assembly 250 can include The axial
compression slider 280 can be configured to axially compress the
stent to facilitate positioning and longitudinal and rotational
orientation. In particular, after the stent has been partially
exposed and the exposed portion of the stent is able to radially
expand, longitudinal proximal movement of the axial compression
slider 280 can cause radial expansion and/or supplement
self-expansion of the exposed portion of stent. In this manner, a
practitioner can partially deploy the stent in a "jackhammer" type
motion to compress the braided stent, reposition the stent as
necessary to best interface with the vasculature (e.g., achieve
opposition between the vessel wall and stent graft to form or
confirm a seal) and/or other adjacent device components, and then
fully deploy the stent by allowing the stent to self-expand (or
supplementing radial expansion with the axial compression slider
280) without constraint by the outer sheath, top cap, and/or distal
collet. Furthermore, the practitioner can make adjustments by
manipulating the axial compression slider 280 in a stent tensioning
direction, thereby radially compressing the stent again to allow
for repositioning of the stent.
[0081] In one embodiment, the axial compression slider 280 is
configured to expand the stent from a first radius when in its
radially compressed configuration to a deployment radius that is
sufficiently large to form an at least substantially fluid-tight
seal against the vessel in which the stent is being deployed. For
example, the axial compression slider 280 can be configured to
expand from a smaller first radius to a larger deployment radius,
where the deployment radius is between approximately three and five
times the first radius (e.g., at least four times the first
radius). However, in other embodiments the expansion ratio, or
other relative change in cross-sectional stent dimension (e.g.,
diameter), can depend on the specific application.
[0082] Referring to FIG. 6C, the axial compression slider 280 (FIG.
6E) can engage a distal bearing assembly 282, which is coupled to
an inner shaft 232 by epoxy or any suitable fastening means. The
inner shaft 232 can be in mechanical communication with the distal
end of stent. Longitudinal movement of the compression slider 280
can correspond to longitudinal movement of the distal bearing
assembly 282. The distal bearing assembly 282 can ride within one
or more slots 274 on opposite sides of the handle housing 270 (FIG.
6A), and this longitudinal movement of the bearing assembly 282 can
correspond to longitudinal movement of the distal end of the stent.
In various embodiments, (e.g., when the proximal end of the stent
is substantially stationary), proximal movement of the slider 280
will proximally pull the distal end of the stent so that the stent
is in an axially compressed, radially expanded state. Similarly,
distal movement of the slider 280 after some stent compression will
distally extend the distal end of the stent so the stent is in a
tensioned, radially constrained state, thereby allowing the
practitioner to reposition the subsequently constrained stent
relative to the vasculature. As shown in FIG. 6E, the axial
compression slider 280 can include a locking tab 284 that
selectively engages with one or more notches 272 (FIGS. 6A and 6C)
and/or other types of locking portions on the handle of the housing
270. Engagement of the locking tab 284 with one of the notches 272
enables the operator to fix longitudinal position of the partially
expanded/deployed stent in anticipation of full deployment. When
the locking tab 284 is disengaged from the notches 272, such as by
a depression of a lever or button by the device operator, the
slider 280 is free to longitudinally move and axially compress the
stent. When the locking tab 284 is engaged with one of the notches
272, the longitudinal position of the slider 280 is set. In various
embodiments, the set of notches 272 can correspond to discrete
degree of stent compression that the operator can use to gauge
stent deployment. In other embodiments, the handle assembly 250 can
include any suitable locking mechanism for securing the
longitudinal position of slider 280.
[0083] Other variations of the handle assembly 250 can include
other mechanisms for facilitating axial stent compression
independently of the first and second lead screws 260 and 262. For
example, the embodiment of FIGS. 8A and 8B includes an axial
compression slider 380 and/or other stent compressor that can be
used to rotationally and longitudinally manipulate a compression
coupler 384, which is coupled to the inner shaft by epoxy and/or
any suitable fastening means. Similar to the slider 280 described
above with reference to FIGS. 6A-6E, longitudinal translation of
the slider 380 corresponds, through mechanical communication, to
longitudinal movement of the distal end portion of a stent for
selective and reversible axial compression of the stent. As shown
in FIG. 8B, the longitudinal position of the slider 380 can be
locked by rotating the slider 380 so that the coupler 384 engages
one of the plurality of slider lock notches 382 in the handle
housing. As another example, the embodiment of FIG. 9 includes a
compression lead screw 380' coupled to the inner shaft by epoxy or
any suitable fastening means. Rotation of the compression lead
screw 380' will result in its longitudinal translation and
corresponding longitudinal motion of the inner shaft and distal end
portion of the stent for selective and reversible axial compression
of the stent.
[0084] Referring back to FIGS. 6A-6E, the handle assembly 250
embodiment can further include a top cap slider 290 (FIG. 6E) that
is configured to distally move the top cap 222. The top cap slider
290 can engage a proximal bearing assembly 292 (FIG. 6C), which is
coupled to the tip tube 230 by epoxy or any suitable fastening
means. Like the distal bearing assembly 282, the proximal bearing
assembly 292 can ride along one or more slots 274 on opposite sides
of the handle housing during its longitudinal movement. Because tip
tube 230 is in mechanical communication with the top cap 222,
longitudinal movement of the top cap slider 290 corresponds to
longitudinal movement of the top cap 222. In particular, sufficient
distal movement of the top cap slider 290 can completely expose a
distal end portion of the stent. As shown in FIG. 6E, the top cap
slider 290 can be selectively coupled to the axial compression
slider 280 by means of a removable slider collar 294. When the
slider collar 294 is coupled to both the compression slider 280 and
the top cap slider 290 (e.g., with a snap fit or fasteners) the
compression slider 280 and the top cap slider 290 can move in
tandem. When the slider collar 294 is removed, the compression
slider 280 and the top cap slider 290 are movable independent of
one another. In some embodiments, the top cap slider 290 can also
be locked directly to the compression slider 280 by a snap fit
and/or other suitable fasteners (e.g., after the slider collar 294
is removed). An alternative embodiment of the top cap slider 290 is
shown in FIGS. 10A and 10B, in which the top cap slider 290 is
positioned on the proximal end portion of the housing and engages
proximal bearing assembly 292 in a manner similar to that described
above.
[0085] Other variations of the handle assembly 250 can include
other mechanisms for moving a top cap. For example, the embodiment
of FIGS. 8A and 8B includes a tip release screw 390. When turned,
the tip release screw 390 can move distally and cause the top cap
to move distally and release the distal end portion of the stent.
The threads of the tip release screw 390 can prevent accidental
deployment as the result of pushing axially on the head of the tip
release screw 390. As another example, the embodiment of FIG. 9
includes a tip release pusher 390'. When pushed in a distal
direction, the tip release pusher 390' moves distally and causes
the top cap to move distally and release the distal end portion of
the stent. In these and other embodiments, additional locks and/or
other safety mechanisms (e.g., collars, mechanical fasteners,
mechanical keys, etc.) can be removeably coupled to the mechanisms
for moving the top cap to reduce the likelihood of accidental or
premature deployment of the top cap.
[0086] FIGS. 11A-12D show another embodiment of the handle assembly
450 with the first and second lead screws 460 and 462. In this
embodiment, the handle assembly 450 is configured to deploy, from a
tubular enclosure 420 (FIG. 11A), a proximal end portion 410p of
the stent 410 before the distal end portion 410d of the stent 410
during a "reverse deployment" stent delivery. By deploying the
proximal end portion 410p of the stent 410 first and maintaining
the axial position of the exposed proximal end of the stent 410,
the handle assembly 450 can facilitate accurate and precise
positioning of the proximal end portion 410p of the stent 410. This
functionality can be useful for applications in which it is
important to align the proximal end of the stent 410 correctly. For
example, assuming an approach through the femoral artery typical of
EVAR procedures for AAA repair, this embodiment can be used to
deploy a stent graft in an iliac artery for overlapping and sealing
with an implanted aortic stent as it may be desirable to ensure
that (1) adequate stent length will be deployed in the iliac
artery, and/or (2) no vessels branching from the iliac artery
(e.g., the hypogastric artery) are inadvertently blocked. In other
embodiments, the handle assembly 450 may be used in other
applications that benefit from accurate and precise placement of a
proximal end of the stent.
[0087] In the embodiment of the handle assembly 450 shown in FIGS.
11A-12D, the first lead screw 460 can be directly or indirectly
coupled to a tubular enclosure that can travel in a distal
direction to expose the stent. For example, the first lead screw
460 can be in mechanical communication with the top cap 424 of the
delivery catheter such that distal translation of the first lead
screw 460 actuates corresponding distal translation of the top cap
424. As shown in FIG. 12D, the first lead screw 460 can be coupled
to a proximal coupler 440, which is in turn coupled to the tip tube
430, and the tip tube 430 is coupled to the top cap 424. In
particular, sufficient distal movement of the first lead screw 460
and the proximal coupler 440 will cause the top cap 424 (and/or any
outer sheath attached to and extending the top cap 424 along the
stent) to move distally enough to expose the proximal end portion
of the stent, and additional distal motion of the first lead screw
460 will eventually cause top cap 424 to release the entire length
of the stent, thereby allowing the stent to self-expand.
Alternatively, the coupling between the first lead screw 460 and
the top cap 424 can include any other suitable mechanical
communication between the first lead screw 460 and the top cap 424,
such as the direct or indirect methods described above with respect
to the embodiment of FIGS. 6A-6E. In further embodiments, the
coupling can additionally or alternatively include any suitable
kind of coupling that effectuates movement of the distal top cap
424.
[0088] In the embodiment of the handle assembly 450 shown in FIGS.
11A-12D, the second lead screw 462 is directly or indirectly
coupled to a distal end portion 410d of the stent 410 such that
translation of the second lead screw 462 actuates corresponding
translation of the distal end portion 410d of the stent 410. The
second lead screw 462 can be configured to be in mechanical
communication with the distal coupler 442 (FIG. 12C), which is
coupled to the inner shaft 432, and the inner shaft 432 is engaged
with the distal end portion 410d of the stent 410 by the leading
collet 428. More particularly, as shown in FIG. 12C, the second
lead screw 462 has a coupler engagement surface 464 moving within a
neck 444 of the distal coupler 442 such that when second lead screw
462 moves proximally enough across the neck 444, the coupler
engagement surface 464 will abut and engage the distal coupler 442.
After this engagement occurs, additional proximal movement of the
second lead screw 462 will cause corresponding proximal advancement
of the distal coupler 442, the inner shaft 432, and the distal end
portion 410d of the stent 410. Alternatively, the coupling between
the second lead screw 462 and the distal end portion 410d of the
stent 410 (or any suitable stent portion) can include any suitable
mechanical communication.
[0089] FIG. 13 is a partially transparent, isometric view of a
portion of a handle assembly 550 configured in accordance with
another embodiment of the technology. The handle assembly 550 can
include a first lead screw 560 having a first pitch and a second
lead screw 562 having a second pitch different from the first
pitch. Similar to the handle assemblies in the embodiments
described above, one of the lead screws 560 or 562 is in mechanical
communication with a tubular enclosure surrounding a stent, and the
other lead screw 560 or 562 is in mechanical communication with
either a proximal or distal end portion of the stent. The first and
second lead screws 560 and 562 can be of opposite handedness and
engaged with a shaft 564 such that a clockwise or counterclockwise
rotation of the shaft 564 will cause the lead screws 560, 562 to
axially translate in opposite directions. In some variations,
second lead screw 562 can be internally threaded with a thread
corresponding to the pitch and handedness of first lead screw 560,
such that the first lead screw 560 can pass longitudinally within
the second lead screw 562 as the lead screws 560, 562 axially
translate.
[0090] FIG. 14 illustrates a handle assembly 650 configured in
accordance with yet another embodiment of the technology. The
handle assembly 650 can include a series of coaxial, nested first
and second racks 660 and 662 that engage with respective first and
second pinions 670 and 672 such that the movements of racks 660,
662 and pinions 670, 672 are interrelated by gearing. One of the
racks 660 or 662 can be configured to be coupled to a tubular
enclosure (e.g., a catheter or top cap), and the other rack 660 or
662 can be configured to be coupled to a stent (e.g., using similar
attachment mechanisms as described above). Variations of the handle
assembly 650 of FIG. 14 can include different actuation inputs that
induce opposing movement of the racks 660 and 662. For example,
rotation of either the first pinion 670 or the second pinion 672 by
a handle component (not shown) will effectuate the simultaneous
longitudinal translations of the first and second racks 660 and 662
in opposite directions. Alternatively, actuation of either the
first rack 660 or the second rack 662 by a handle component (not
shown) will be translated through the gearing to effectuate the
simultaneous longitudinal translation of the other rack 660 or 662
in an opposite direction. The pitches of the racks 660, 662 and the
pinions 670, 672 can vary to facilitate different absolute and
relative rates of travel of the racks 660, 662 for each revolution
of the pinions 670, 672. In still other embodiments, the handle
assembly 650 can include suitable additional features, and/or have
a different suitable gearing configuration.
Other Aspects of Handle Assemblies
[0091] In some embodiments, the handle assemblies described above
can include a delay system that delays the synchronized actions of
exposing a stent and axially compressing the stent until after a
portion of the stent is exposed. In particular, in some variations,
the delay system delays mechanical communication between a moving
position compensating element and the stent until a predetermined
portion of the stent is exposed from a tubular enclosure. In other
variations, the delay system delays movement of the position
compensating element until a predetermined portion of the stent is
exposed from the tubular enclosure. The delay can be based on, for
example, the distance that the tubular enclosure must travel before
beginning to expose the stent. The delay system can accordingly
avoid premature radial expansion of the stent within the tubular
enclosure.
[0092] FIG. 6D illustrates one embodiment of a delay system in
which there is a spatial longitudinal offset between the proximal
coupler 240 and the coupler engagement surface 264 of the second
lead screw 262. The longitudinal offset corresponds to a
predetermined delay distance. Upon rotation of the shaft portion of
the handle assembly, both the first and second lead screws 260 and
262 begin to move in opposite directions, but because of the
longitudinal offset between the coupler engagement surface 264 of
the second lead screw 262 and the proximal coupler 240, the coupler
engagement surface 264 does not abut the proximal coupler 240 until
the second lead screw 262 has traversed the offset. In other words,
rotation of the handle actuates both lead screws 260, 262, but
during an initial delay lasting until the coupler engagement
surface 264 has traversed the predetermined delay distance,
rotation of the handle can result in translation of first lead
screw 260 to partially expose the stent without resulting in axial
compression of the stent.
[0093] FIG. 12C illustrates another embodiment of a delay system in
which the distal coupler 442 with the neck 444 is responsible for a
delay in synchronization, where the length of the neck 444 is equal
to a predetermined delay distance. Upon rotation of the shaft
portion of the handle assembly 450, both the first and second lead
screws 460 and 462 begin to move in opposite directions, but
because of the neck 444 of distal coupler 442, the coupler
engagement surface 464 of the second lead screw 462 does not abut
the shoulder of the distal coupler 442 until the second lead screw
462 has traversed the neck 444. In other words, similar to the
embodiment of FIG. 6D, rotation of portions of the handle assembly
450 actuates both lead screws 460, 462, but during an initial delay
lasting until the coupler engagement surface 464 has traversed the
predetermined delay distance across the coupler neck 444, rotation
of the handle can result in translation of the first lead screw 460
to partially expose the stent, without resulting in axial
compression of the stent.
[0094] In other embodiments of delay systems, the proximal or
distal coupler can be in a reverse configuration with respect to
the uncovering element and the position compensating element,
and/or the delay system can include other components to facilitate
a delay. Furthermore, in some embodiments, the handle assembly does
not include a delay system to delay axial compression of the stent.
In an auto-compression embodiment, the simultaneous actions of
exposing the stent and axially compressing the stent can be
carefully synchronized (e.g., with no delay of either action) with
relative rates appropriate so that a suitable amount of axial
compression is performed at the same time the stent is initially
exposed.
[0095] In some embodiments, the housing can include a mechanism
that operates additionally or alternatively to the axial
compression slider 280 (FIG. 6E) and radially compresses the stent
diameter after partial deployment. For example, as shown in FIGS.
10A and 10B, the handle assembly can include a repositioning ring
281 that, when moved longitudinally along the axis of the housing,
can be used to reduce the outer profile of a stent that has been
axially compressed to a radially expanded state (e.g., by
simultaneous auto-compression as described above, or by an
independent axially compressing component). The repositioning ring
281 can be in mechanical communication with an end portion of the
stent by a push or pull tube such that proximal or distal movement
of the repositioning ring 281 causes corresponding movement of an
end of the stent, thereby extending and radially contracting the
stent.
[0096] As another example, the stent can be undeployed by
backdriving the shaft portion of the handle, rotating the shaft
portion in a direction opposite the direction required for
deployment, such as to reverse the paths of the lead screws. In
this reverse deployment, the stent becomes elongated and radially
compressed, and the sheath recovers the exposed portion of the
stent. Once the stent returns to its radially compressed state, the
device operator can reposition the stent relative to the
surrounding environment.
[0097] As shown in FIG. 15A, in some embodiments the housing
further includes a rotational control mechanism 350 that limits
rotation of the shaft portion to rotation in a deployment direction
(i.e., the direction that actuates stent deployment). In preventing
the rotation of the shaft portion in the direction opposite the
deployment direction, the rotational control mechanism 350 can
prevent axial compression of the stent when the stent is still
radially constrained in the tubular enclosure, as well as
selectively lock against reverse deployment while stent deployment
is in progress. In some embodiments, the rotational control
mechanism 350 can be selectively disengaged so as to selectively
permit rotation in the direction opposite the deployment direction,
such as to permit reverse deployment. When the rotational control
mechanism 350 is disengaged, the shaft portion can be rotated in
the direction opposite the deployment direction in order to
reconstrain the stent within the tubular enclosure. By permitting
reverse deployment, the handle assembly can allow repositioning of
the entire stent even after the stent has been partially deployed,
if so desired.
[0098] As shown in FIGS. 15A-15C, a locking collar can define at
least one channel 352 and the rotatable shaft portion can define at
least one spring tab 354. As long as the rotational control
mechanism 350 is engaged, the spring tab 354 flexes to accommodate
rotation of the shaft portion in the deployment direction, but the
spring tab 354 engages and stops against the channel 352 when the
shaft portion is rotated in the direction opposite of the
deployment direction. When the spring tab 354 stops against the
channel 352, tactile and/or audio clicking feedback can inform the
handle operator that he or she has rotated the shaft in an
impermissible direction. The locking collar can include multiple
channels 352 (e.g., four channels 352 equally circumferentially
distributed around the collar), such that a single spring tab 354
on the shaft portion permits no more than ninety degrees of
rotation in the non-deployment direction. However, in other
embodiments the rotational control mechanism 350 can include any
suitable number of channels 352 and/or spring tabs 354.
Disengagement of the rotational control mechanism 350 can be
performed, for example, by sliding the locking collar distally or
proximally out of the rotational path of the spring tab 354. For
example, as shown in FIG. 15C, moving the locking collar both
rotationally and longitudinally to navigate a key 358 on the shaft
portion through a guide path slot 356 in the locking collar will
permit the locking collar to be oriented in a manner where the
spring tab 354 will not engage with channel 352. Alternatively, the
locking collar can be completely removed to disengage the
rotational control mechanism 350. Furthermore, the housing can
additionally or alternatively include other suitable features for
selectively restraining rotation of the shaft portion to one
direction.
[0099] In some embodiments, the housing additionally or
alternatively includes other control mechanisms that selectively
prevent rotation in a deployment direction. For example, the
housing can include an additional or alternative rotational control
mechanisms that prevent rotation of the shaft portion in the
deployment direction until intentional steps are taken to disengage
the rotational control mechanism, such as to prevent premature
deployment of the stent (e.g., when the delivery catheter is not
yet at the target area).
[0100] In further embodiments, the handle assembly can include one
or more points of entry for contrast fluid. For example, as shown
in FIG. 7, the distal coupler 242 can be coupled to contrast tubing
244 to facilitate injection of contrast fluid through the delivery
catheter to the stent region. The injected contrast fluid aids in
imaging the target area surrounding the stent for purposes of
advancing the delivery catheter and positioning and aligning the
stent during deployment. The distal coupler 242 can include
fluid-tight seal 246 that prevents contrast fluid and/or
recirculating blood from entering the handle assembly. The
fluid-tight seal 246 can include, for example, one or more o-rings.
In other embodiments, the distal coupler 242 can additionally or
alternatively include other suitable sealing features. Since in
these embodiments the distal coupler 242 and sealing mechanism 246
may be in contact with recirculating blood, the distal coupler 242
and sealing mechanism 246 can be made of any suitable biocompatible
material. In other examples, other proximal and/or distal couplers
in handle assembly can be coupled to contrast tubing, and/or the
handle assembly can include other fluid-tight couplers as
appropriate. Furthermore, the couplers for introducing couplers can
define a circular, annular space or other suitable non-circular
shapes.
Selected Embodiments of Methods for Delivering Stent Grafts
[0101] In various embodiments, a method for implanting a stent
graft at a target area for treatment of an aneurysm includes:
advancing, toward the target area, a catheter comprising a tubular
enclosure covering the stent graft; positioning the stent graft
proximate to the target area; deploying the stent graft; allowing
the stent graft to anchor in or at the target area; and withdrawing
the catheter from the target area. Deploying the stent graft can
include effectuating simultaneous, opposing translations of first
and second handle components such that the first the handle
component longitudinally displaces the tubular enclosure in a first
direction, and the second handle component axially compresses the
stent graft in a second direction opposite the first direction. The
method is described further with reference to particular handle
assemblies shown in FIGS. 16A-18E, but the method is not limited to
use of the handle assemblies described herein. Furthermore, though
the method is primarily described in regards to deploying a
specific design of stent graft, it should be understood that the
method can similarly be used to deploy other kinds of stent grafts
or endografts, a bare stent, or any suitable kind of stent.
[0102] Various aspects of advancing the catheter, positioning the
stent graft, allowing the stent graft to anchor in the target area,
and withdrawing the catheter can be similar to those steps
described in U.S. Patent Application Publication No. 2011/0130824,
which is incorporated herein by reference in its entirety. For
example, advancing the catheter can involve entry into a blood
vessel using a percutaneous technique such as the well-known
Seldinger technique.
[0103] With respect to deploying the stent graft, in one embodiment
of the method, a practitioner or device operator can displace the
tubular enclosure in a proximal direction to expose only a portion
of the stent graft, constrain a distal endpoint of the stent graft
in a radially compressed state, and axially compress the stent
graft to radially expand only the exposed portion of the stent
graft. For example, the device operator can initially rotate a
shaft portion of handle to move the outer sheath 724 and expose a
portion of the stent graft 710 (e.g., 2-3 inches). A delay system
can stall any stent graft compression resulting from this initial
rotation, though in other embodiments some amount of stent graft
compression can automatically occur during this initial rotation.
The top cap 722 can still constrain the distal end of the stent
graft after this initial handle rotation. Proximal movement of an
axial compression slider, which is coupled to the distal end of the
stent graft 710d by leading collet 728, pulls leading collet 728
and distal stent graft end 710d proximally, which axially
compresses and radially expands the exposed portion of the stent
graft, as shown in FIG. 16A. During this time, the practitioner can
view, through imaging methods and/or use contrast fluids and
radiopaque markers, the rotational and longitudinal orientation of
the exposed stent graft.
[0104] If not satisfied with the position and alignment of the
stent graft, the device operator can radially collapse the stent
graft down to an outer profile small enough for stent graft
repositioning. In particular, distal movement of the axial
compression slider pushes leading collet 728 and distal stent graft
end 710d distally, which tensions and radially collapses the
exposed portion of the stent graft to a degree suitable for
repositioning. The repositioning process can repeat until the
practitioner is satisfied. In some embodiments, the method can
additionally or alternatively include resheathing the exposed stent
graft with the tubular enclosure. For example, the device operator
can rotate (backdrive) the shaft portion of the handle in the
direction opposite that for actuating deployment, in order to
reposition the sheath over the previously exposed portion of the
stent graft.
[0105] When satisfied with the position and alignment of the stent
graft, the device operator can release the distal end of the stent
graft from its radially compressed state. For example, the device
operator can move a tip slider in a distal direction to remove the
top cap 722 from the stent graft, thereby releasing the distal end
of the stent graft, as shown in FIG. 16B. However, the method can
involve other actuation means, such as rotating a tip screw, to
remove the top cap or other appropriate enclosure.
[0106] Once the distal end of the stent graft is released, the
device operator can simultaneously further expose the stent graft
by displacing the tubular enclosure and axially compress the stent
graft by advancing the unexposed proximal end of the stent graft as
the tubular enclosure is displaced, thereby compensating for stent
graft foreshortening. For example, shown in FIG. 16B, the device
operator can manipulate the handle to induce opposing translations
of first and second handle components, where one handle component
longitudinally displaces the tubular enclosure (e.g., outer sheath
224) in a proximal direction while the other handle component
axially compresses the stent graft with a distally-directed force
(advancing a proximal end of the stent graft 710d via trailing
collet 226).
[0107] With respect to deploying the stent graft, in another
embodiment of the method shown in FIG. 17, in a reverse deployment
scenario, the device operator manipulates the handle to induce
opposing translations of first and second handle components, where
one handle component longitudinally displaces the tubular enclosure
(e.g., top cap 824 via tip tube 830) in a distal direction while
the other handle component axially compresses the stent graft 810
with a proximally-directed force (e.g., retracting a distal end of
the stent graft 810d via leading collet 828 and inner shaft
832).
[0108] FIGS. 18A-18E show an exemplary embodiment of the method
used specifically to deliver stent graft grafts for treatment of an
abdominal aortic aneurysm. In this specific application of the
method, the method deploys stent grafts with D-shaped
cross-sections as described in U.S. Patent Application Publication
No. 2011/0130824, where the flat portions of the D-shaped stent
grafts press against each other to form a straight septum and the
curved portions of the D-shaped stent grafts press against the
aortic wall to form a seal against the aortic wall. The figures
show and are described with reference to the delivery device
embodiment of FIG. 6A, but it should be understood that any
suitable embodiments and variations of the device can similarly be
used in the method. Furthermore, FIGS. 18A-18E show and are
generally described with respect to the operations of handle of
only one delivery device, which is typically identical to the
delivery device used for deploying the depicted contralateral stent
graft.
[0109] In FIG. 18A, stent grafts 910 are positioned superior to the
aneurysm and partially unsheathed. The catheters of two instances
of the delivery system have been advanced toward the target area in
an aorta using various techniques, such as over-the-wire
(guidewires not shown), with a first catheter advanced along the
left iliac artery, and a second catheter advanced along the right
iliac artery. The catheters have been advanced until the top caps
922 and stent grafts 910 are positioned superior to the aneurysm,
where radiopaque markers can aid correct placement of the stent
grafts. In one embodiment, the catheters cross paths within the
aneurysm such that the distal end of each catheter approach and/or
touch the side of the aortic wall that is opposite the side of
entry. In other words, the crossing of catheters may induce a stent
graft 910 passing through the aneurysm from the left iliac artery
to appose the right side of the aortic wall, and a stent graft 910
entering from the right iliac artery to appose the left side of the
aortic wall. On each delivery device, rotation of handle portion
952a has caused internal threads of handle portion 952a to
simultaneously engage first and second lead screws 960 and 962,
resulting in proximal translation of first lead screw 960 and
distal translation of second lead screw 962. Proximal movement of
first lead screw 960 has caused outer sheath 924 to retract and
expose a portion of stent graft 910, though top cap 922 still
constrains the distal end of stent graft 910. Meanwhile, in a delay
system (not shown) as described above with respect to FIG. 6D,
distally-travelling lead screw 962 has not traversed the
predetermined delay distance, such that lead screw 962 does not yet
axially compress the exposed stent graft 910.
[0110] In FIG. 18B, the stent grafts 910 are slightly axially
compressed such that the exposed portions of stent grafts 910 are
slightly radially expanded. In particular, on each delivery device,
the axial compression slider (represented by box 980), which is
coupled to distal bearing assembly 982 in mechanical communication
with the distal end of stent graft 910, has been pulled proximally
to axially compress the exposed portion of stent graft 910. As
described above, such axial compression induces and/or supplements
the radial self-expansion of the stent graft 910. Since in each
device, tip slider (represented by box 990) is coupled to axial
compression slider 980 by removable slider collar 994, top cap 922
moves in tandem with the distal end of the stent graft 910.
Additionally, axial compression slider 980 can optionally be moved
distally to tension and radially collapse the exposed portion of
the stent graft 910.
[0111] In other words, the longitudinal position of the axial
compression slider 980 corresponds to the degree of radial
expansion, so the device operator can move the axial compression
slider 980 both proximally and distally to adjust the radial
expansion and radial contraction, respectively, of the stent graft
910. Furthermore, the device operator can adjust the longitudinal
position of the catheter as a whole by withdrawing and/or advancing
the entire catheter, to adjust the longitudinal position of the
stent grafts 910. Partial radial expansion of the stent grafts,
when viewed under fluoroscopy by the device operator, aids optimal
rotational and/or longitudinal positioning of the stent grafts 910,
both relative to each other and relative to the aortic wall.
[0112] In particular, each partially deployed stent graft 910 is
longitudinally positioned such that its graft material is aligned
with (just inferior to) a renal artery in order to maximize overlap
between the anchoring bare stent portion of stent graft 910 and
healthy aortic neck tissue, without resulting in the graft material
blocking blood flow to the renal arteries. Additionally, as shown
in FIG. 18C, in instances in which the stent grafts 910 are being
deployed in a patient having longitudinally offset renal arteries,
the stent grafts 910 are optimally positioned with a corresponding
longitudinal offset in order to accommodate the offset renal
arteries without sacrificing coverage nor blocking blood flow to
the renal arteries.
[0113] Furthermore, each partially deployed stent graft 910 is
rotationally oriented such that the flat portions of the D-shaped
stent grafts 910 press against each other to form a straight septum
and the curved portions of the D-shaped stent grafts 910 press
against the aortic wall to form a seal against the aortic wall.
[0114] In FIG. 18C, the stent grafts are longitudinally and
rotationally oriented in the desired manner, and further proximal
retraction of axial compression slider 980 has induced additional
radial expansion of the stent graft 910 to cause stent graft 910 to
press against the aortic wall. The two stent grafts 910 in
conjunction can be radially expanded to a have a deployment radius
sufficiently large to form a complete seal between them, as well as
with the aorta wall superior to the aneurysm. This seal can be
verified or confirmed by introducing contrast fluid through the
catheter (e.g., through contrast tubing in the handles) and viewing
whether the expanded stent grafts 910 prevent contrast flow across
the sealed region. Alternatively, other methods of contrast
introduction can be performed to confirm the seal of stent grafts
910 against each other and/or against the vessel wall. As described
above with respect to FIGS. 6C and 6E, axial compression slider 980
locks longitudinally in place with notches on the housing, in
anticipation of full deployment of the stent grafts.
[0115] In FIG. 18D, the distal ends of stent grafts 910 are freed
from top cap 922 and allowed to self-expand against each other and
against the aortic wall. If the stent grafts 910 have barbs or
other suitable anchoring mechanisms, the stent grafts have become
anchored at their deployed position. On each delivery device,
slider collar 994 has been removed to allow tip slider 990 to move
independently of axial compression slider 980. The tip slider 990
has been moved distally to cause top cap 922 to move
correspondingly move distally and release the distal end of the
stent graft. After the distal end of the stent graft 910
self-expands, slider 990 may couple directly to axial slider 980.
At this point during deployment, the device operator may choose to
inject contrast fluid through one or both catheters, with contrast
couplers described above, in order to verify quality of the seal
formed between the stent grafts and with the aortic wall.
[0116] Following verification of position and seal, resumed
rotation of the handle portion in each delivery device again
effectuates the opposing longitudinal translations of the first and
second lead screws 960 and 962. In particular, after the second
lead screw 962 traverses the predetermined delay distance, the
first lead screw 960 continues to proximally retract outer sheath
924 and the second lead screw 962 distally advances the proximal
end of stent graft 910.
[0117] In FIG. 18E, the catheters have been withdrawn from the
stent grafts 910 following full deployment of the stent grafts. The
two simultaneous actions of the lead screws 960 and 962 during
deployment have compensated for the displacement effects of stent
graft foreshortening that would otherwise occur, thereby ensuring
that the distal ends of stent grafts 910 maintain their respective
positions during deployment. The stent grafts of FIG. 18E are shown
with inferior ends terminating within the aneurysm. However, in
other embodiments, each stent graft can extend into and anchor with
a respective iliac artery. For example, the inferior graft end of
the stent grafts 910 can terminate in the common iliac arteries
immediately superior to the internal iliac arteries so as not to
block blood flow to the internal iliac arteries. However, the stent
grafts 910 can be positioned in any suitable manner.
[0118] FIGS. 19A-19C show another exemplary embodiment of the
method, extending that described with respect to 18A-18E. This
specific application of the method deploys iliac stent grafts 1010,
each of which couples to and extends a respective stent graft 910
deployed as described above. The figures show and are described
with reference to the delivery device embodiment of FIG. 12A, but
it should be understood that any suitable embodiments and
variations of the device can similarly be used in the method.
Furthermore, FIGS. 19A-19C depict the operations of handle of only
one delivery device, which is typically identical to the delivery
device used for deploying the depicted contralateral stent
graft.
[0119] In FIG. 19A, stent grafts 1010 are partially deployed
adjacent to previously deployed stent grafts 910. The catheter of
each delivery device was advanced over guidewires toward the
aneurysm and into the lumen of a corresponding stent graft 910. The
proximal graft end of each stent graft 1010 was optimally aligned
to be immediately superior to the internal iliac arteries, so as
not to block the internal iliac arteries. However, the stent grafts
1010 can be positioned in any suitable manner. On each delivery
device, rotation of handle portion 1052a relative to handle portion
1052b has caused internal threads of handle portion 1052a to
simultaneously engage first and second lead screws 1060 and 1062,
resulting in distal translation of first lead screw 1060 and
proximal translation of second lead screw 1062. Distal movement of
first lead screw 1060, which is in mechanical communication through
tip tube 1030 to top cap 1024, has caused top cap 1024 to advance
distally and expose a portion of stent graft 1010. The stent graft
exposure began at the proximal end of the stent graft, which
radially expanded off of docking tip 1026. Through a delay system
(not shown) as described above with respect to FIG. 12C,
proximally-travelling lead screw 1062 travels a predetermined delay
distance before it becomes in mechanical communication with the
distal end of stent graft 1010 through inner shaft 1032. Once the
lead screw 1062 has traversed the predetermined delay distance, its
proximal translation axially compresses the stent graft 1010 by
proximally retracting the distal end of the stent graft 1010.
[0120] In FIG. 19B, the top caps 1024, and/or associated outer
sheath if present, have advanced distally enough to release the
distal ends of the stent grafts 1010, thereby freeing the distal
end of the stent graft 1010. The superior ends of stent grafts 1010
are expanded within in the inferior ends of stent grafts 910, such
as to extend the lumens of stent grafts 910 at a joining within the
aneurysm. In other embodiments, the stent grafts 1010 can couple to
the stent grafts 910 in any suitable location. At this point of
deployment, the device operator may choose to inject contrast fluid
through one or both catheters, using contrast couplers as described
above, in order to verify quality of seal formed between stent
grafts 910 and 1010, and/or with the iliac arterial wall.
[0121] In FIG. 19C, the catheters have been withdrawn from the
stent grafts 1010 following full deployment of the stent grafts.
The two simultaneous actions of the lead screws 1060 and 1062
during deployment of compensated for the displacement effects of
stent graft foreshortening that would otherwise occur, thereby
ensuring that the proximal ends of stent grafts 910 maintain their
respective positions during deployment.
[0122] The handle assemblies and stent delivery methods shown and
described herein offer several advantages over previous devices and
stent delivery methods. For example, the handle assemblies provide
for straightforward delivery of a stent graft to an artery while
maintaining initial stent graft marker positions relative to a
destination arterial wall. Embodiments employing opposing screws
provide a user with the ability to deliver a stent graft at a high
force with relatively little mechanical effort. This allows a user
to exercise improved control over the delivery process, such as by
enabling the user to control the outer diameter and/or length of
the deployed stent. Further, the mechanisms disclosed herein
provide effective push/pull motion while minimizing the number of
parts, assembly time, and cost. The push/pull components move at
relative rates according to the predetermined payout ratio (which,
in the lead screw embodiment described above, is dependent on the
difference in pitch between the lead screws), and determine the
rate of stent deployment and degree of stent radial expansion. Such
control over the rate of stent deployment and degree of stent
radial expansion can allow the handle assemblies to maintain a low
profile and minimize the overall bulk of the delivery device.
[0123] From the foregoing, it will be appreciated that specific
embodiments of the technology have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the disclosure. Certain aspects of the
new technology described in the context of particular embodiments
may be combined or eliminated in other embodiments. Additionally,
while advantages associated with certain embodiments of the new
technology have been described in the context of those embodiments,
other embodiments may also exhibit such advantages, and not all
embodiments need necessarily exhibit such advantages to fall within
the scope of the technology. Accordingly, the disclosure and
associated technology can encompass other embodiments not expressly
shown or described herein.
* * * * *