U.S. patent application number 10/806263 was filed with the patent office on 2004-09-16 for channeled vascular stent apparatus and method.
This patent application is currently assigned to Norman Noble, Inc.. Invention is credited to Miller, Jeffrey A., Noble, Lawrence E..
Application Number | 20040181275 10/806263 |
Document ID | / |
Family ID | 24468730 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040181275 |
Kind Code |
A1 |
Noble, Lawrence E. ; et
al. |
September 16, 2004 |
Channeled vascular stent apparatus and method
Abstract
A vascular stent having one or more channels in the outer
surface. The channel(s) provide increased flexibility, enhanced
perfusion, increased chronic positional stability, and convenient
dispensing of a medication. Preferably the stent is machined into a
mesh-like pattern and the channel(s) are machined into the stent
elements of the pattern. The channels may be oriented in a variety
of ways. Parallel orientation tends to provide greater enhancement
of perfusion whereas perpendicular orientation provides
differential flexibility. For greater control of differential
flexibility, the channel may be further machined in the stent
element, producing a regain of greater flexibility.
Inventors: |
Noble, Lawrence E.;
(Scottsdale, AZ) ; Miller, Jeffrey A.; (Chompson,
OH) |
Correspondence
Address: |
Lawrence M. Nawrocki
NAWROCKI, ROONEY & SIVERTSON, P.A.
Suite 401, Broadway Place East
3433 Broadway Street Northeast
Minneapolis
MN
55413
US
|
Assignee: |
Norman Noble, Inc.,
|
Family ID: |
24468730 |
Appl. No.: |
10/806263 |
Filed: |
March 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10806263 |
Mar 22, 2004 |
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09616274 |
Jul 14, 2000 |
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6709451 |
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Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
A61F 2002/91541
20130101; A61F 2/915 20130101; A61F 2250/0068 20130101; A61F 2/91
20130101; A61F 2002/91575 20130101; A61F 2230/0013 20130101 |
Class at
Publication: |
623/001.15 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. In a vascular stent having a generally cylindrical shape with an
outer surface and an inner surface, the improvement comprising: at
least one channel in said outer surface.
2. The improvement according claim 1 wherein said channel is
oriented generally parallel to said cylindrical shape.
3. The improvement according to claim 1 wherein said channel is
oriented generally perpendicular to said cylindrical shape.
4. The improvement according to claim 1 wherein said stent is
machined to produce a pattern having at least one stent
element.
5. The improvement according to claim 4 wherein said channel is
machined in one of said at least one stent element.
6. The improvement according to claim 5 wherein said channel
contains a medication.
7. An apparatus comprising: a. A vascular stent having a generally
cylindrical shape and having an outer surface; and b. A channel
located on said outer surface.
8. An apparatus according to claim 7 wherein said vascular stent
further comprises a stent element.
9. An apparatus according to claim 8 wherein said channel is
located on said stent element.
10. An apparatus according to claim 9 wherein said channel is
generally parallel to said cylindrical shape.
11. An apparatus according to claim 9 wherein said channel is
generally perpendicular to said cylindrical shape.
12. A method of preparing a vascular stent comprising: a. Securing
a bio-compatible tube having a generally cylindrical shape with an
outer surface; and b. Providing a channel in said outer
surface.
13. A method according to claim 12 further comprising creating a
pattern in said bio-compatible tube producing a stent element.
14. A method according to claim 13 wherein said providing step
further comprises machining said channel into said stent
element.
15. A method according to claim 14 further comprising the step of
embedding a medication into said channel.
16. An apparatus comprising: a. Means for stenting a vessel having
an outer surface; and b. Means located on said outer surface for
enhancing perfusion.
17. An apparatus according to claim 16 further comprising means
responsively coupled to said outer surface for imparting
differential flexiblity.
18. An apparatus according to claim 16 wherein said enhancing means
further comprises a channel within said outer surface.
19. An apparatus according to claim 18 wherein said outer surface
has a pattern producing a stent element.
20. An apparatus according to claim 19 wherein said channel is
located on said stent element in a generally parallel
direction.
21. An apparatus according to claim 19 wherein said channel is
located on said stent element in a generally perpendicular
direction.
Description
CROSS REFERENCE TO CO-PENDING APPLICATIONS
[0001] None.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to medical devices,
and more particularly relates to devices for reinforcement of a
portion of a vascular wall.
[0004] 2. Description of the Prior Art
[0005] It is well known in the prior art to design and build
apparatus for the treatment of various vascular disorders. It is
common to group these therapies in accordance with the location
within the body of the vessel(s) to be treated. For example,
peripheral vascular therapies treat vascular disease of the
extremities. Similarly, cardiac vascular therapies treat vascular
disease of the coronary system. This method of differentiation is
particularly helpful in that the medical procedures and
corresponding medical devices tend to be specifically tailored to
the individual application.
[0006] The primary disease effecting the coronary system involves
the build-up of material within the lumen of a vessel which
partially or completely occludes the vessel preventing adequate
perfusion. Though there are reported attempts in the literature to
provide treatment using systemic drugs, the primary therapies
involve invasive procedures.
[0007] Perhaps most common, is the by-pass surgical procedure. Most
typically this involves a complete thoracotomy during which those
sections of the coronary arteries which are partially or completely
occluded are surgically removed. If the occluded sections prove to
be quite long, it may be necessary to supply artificial or organic
graft material. Common artificial grafts are made from woven
polymer fibers. Natural grafts may be transplanted from a human or
animal donor or may be harvested from the patient, as with the use
of the patient's saphenous vein.
[0008] The key alternative to by-pass surgery is a less invasive
procedure termed percutaneous translumenal coronary angioplasty
(PTCA). In this procedure, a catheter is inserted percutaneously
into an artery (usually the femoral artery in the leg) and advanced
so that the distal portion, containing an inflatable balloon
reaches the occluded section of the coronary artery. Inflation of
the balloon compresses the occluding material into the vessel wall,
thus increasing the effective cross section of the vessel. Because
the procedure is much less invasive than by-pass, it is much less
costly and much less traumatic.
[0009] However, the prevalent medical concern about PTCA involves
the restenosis rate. A number of preliminary studies have shown
that the rate at which treated vessels subsequently reocclude may
be unacceptably high. The exact mechanism whereby restenosis occurs
is not well understand, notwithstanding considerable on-going
research on the topic. Yet, it seems rather intuitive that the
vessel wall, in the region of the initial lesion, may have been
weakened by the disease. It also seems likely that such a weakened
vessel wall may indeed be further weakened by the PTCA procedure,
itself.
[0010] Thus, it has become a common practice to supplement the PTCA
procedure with the implantation of a stent to provide reinforcement
of the vessel wall. A stent is a generally cylindrical structure
which fits snugly the inside dimension of the inner vessel wall,
providing additional radial strength against restenosis. U.S. Pat.
No. 4,307,723, issued to Finney, describes a stent having a
considerably different configuration which is commonly utilized
within the urinary tract.
[0011] U.S. Pat. No. 5,989,207, issued to Hughes, shows a
relatively elongate stent structure. A stent more specifically
configured for coronary use is seen in U.S. Pat. No. 5,879,370,
issued to Fischell et al. Frantzen, in U.S. Pat. No. 5,718,713,
describes a stent structure produced of a mesh having a flattened
outer surface. U.S. Pat. No. 5,843,172, issued to Yan describes a
stent which is porous to provide chronic release of a drug. With
all of these proposed stent structures, there remain the concerns
of accomplishment of the basic purpose of the stent implantation,
without undue chronic movement and without undue prevention of the
perfusion of the endothelial cells of the stented vessel wall.
SUMMARY OF THE INVENTION
[0012] The present invention overcomes many of the disadvantages
found in the prior art by offering a method of and apparatus for
providing the desired stent functions yet having improved
properties of placement and chronic implantation. These
improvements are derived from the fabrication techniques and
physical configuration of the stent of the present invention.
[0013] The present invention offers a greater opportunity for
positioning and dispensing of medication for chronic drug therapy.
It also provides enhanced chronic retention, improved perfusion,
and differential flexibility in placement.
[0014] In the preferred mode of practicing the present invention,
the stent is fabricated from hollow, cylindrical, tube-like stock
of a biocompatible material, such as titanium or medical grade
stainless steel. The raw stock is preferably "machined" on a
machine tool having a rotary laser cutting head, which cuts a
mesh-like pattern through the wall of the metal stock. It may be
appropriate, in certain other applications, to utilize a
memory-type metal, such as Nitinol.
[0015] In addition to the pattern cut entirely through the stock,
one or more pockets or channels are cut into but not through the
stent wall. These pockets or channels can greatly enhance the
positional stability of the stent, because the channel edges tend
to more tightly grip the vessel wall. The pockets or channels can
incidentally provide a path for blood flow between the outer stent
wall and the endothelial cells of the inner vessel wall. As a
result, the present invention can provide enhanced perfusion of the
stented vessel wall. This enhanced perfusion would especially
benefit stent designs having an embedded medication, because it
would generate greater distribution of the drug.
[0016] The pockets or channels may be machined circumferentially or
longitudinally with respect to the normal blood flow. Longitudinal
orientation would tend to provide the greatest enhancement of
perfusion. This will be the configuration for many
applications.
[0017] Circumferential orientation of the pockets or channels
provides all of the above described benefits and also imparts
differential flexibility along the length of the stent. This occurs
because the reduced metal of the pocket or channel more readily
permits a bend to occur at the location of the channel. This
differential flexibility is particularly useful in effective
placement of the stent, although it is also helpful in positional
retention around bends in the vessel wall.
[0018] One particular embodiment of the present invention provides
for differentially machining a stent mesh pattern at one or more
selected locations. These breaks are useful for imparting a
particular desired degree of differential flexibility.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Other objects of the present invention and many of the
attendant advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings, in which like reference numerals
designate like parts throughout the figures thereof and
wherein:
[0020] FIG. 1 is a diagram schematically showing the overall
medical procedure:
[0021] FIG. 2 is a closeup view conceptually showing the operation
of a vascular stent;
[0022] FIG. 3A is a closeup view conceptually showing a stent
machined into a mesh-like pattern;
[0023] FIG. 3B is a closeup view of the mesh-like stent further
machined with the channels of the present invention;
[0024] FIG. 3C is a closeup view of particular sections of the
stent of FIG. 3B;
[0025] FIG. 4 is a very close up sectioned view of the contact
between the longitudinally channeled stent element and the vessel
wall;
[0026] FIG. 5 is a view similar to FIG. 4 having a medication for
chronic therapy;
[0027] FIG. 6 is a very close up view of the contact between the
laterally channeled stent element and the vessel wall;
[0028] FIG. 7 is a view similar to FIG. 6 having a medication for
chronic therapy;
[0029] FIG. 8 is a very close up view of the contact between the
laterally channeled stent element and the vessel wall showing
differential flexibility around a bend in the vessel wall; and
[0030] FIG. 9 is a view similar to that of FIG. 8 wherein the stent
element has been machined into an articulated bridge.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] FIG. 1 is a diagram 10 schematically showing the overall
medical procedure. Patient 12 has experienced occlusion 14 of
coronary artery 16. This has caused insufficient perfusion to
myocardial tissue 18 of patient 12. To conduct the PTCA procedure
known in the art, the distal portion of a catheter containing a
dilation balloon and stent is percutaneously inserted at incision
22 and advanced through artery 20 into coronary artery 16 to
occlusion 14. Occlusion 14 is opened and stented in the manner
known in the art.
[0032] FIG. 2 is a closeup conceptual view of stent 24 as place
after dilatation of occlusion 14 (not shown). Stent 24 is generally
cylindrical in shape having an inner lumen 26. Preferably, stent 24
is fabricated from thin, biocompatible tubing of stainless steel,
titanium, or Nitinol. For coronary applications, stent 24 has a
length of several millimeters to about one centimeter. A pattern
(not shown in FIG. 2) is machined in the wall of stent 24 as
described below. Stent 24 has an outside diameter which is sized to
snugly fit within the inner lumen of coronary artery 16 after
dilatation.
[0033] FIG. 3A is a close-up view of stent 24 as machined into a
mesh-like pattern. Such machining removes much of the mass from the
implanted stent. The mesh-like pattern increases flexibility of the
stent and improves perfusion to the endothelial cells at the inside
surface of the vessel wall.
[0034] Stent element 28 appears as a portion of the generally
cylindrical surface of stent 24. Stent element 28 has a generally
flat outer surface and a generally flat inner surface. Stent
element 28 is preferably recessed in accordance with one of the
embodiments of the present invention as described below in
detail.
[0035] FIG. 3B is a closeup view of the mesh-like stent of FIG. 3A
further machined to include pockets or channels in accordance with
the present invention. As can be seen, the basic structure of the
mesh-like pattern is a plurality of cells 60 interconnected to
provide the desired size. Each cell 60 contains strut 54 and
internal radial arc 62. The cells are connected via connecting
bridge 56. Articulated bridge 58 is further machined as described
in more detail below to enhance differential flexibility. The ends
of stent 24 are defined by a plurality of end radial arcs 64.
Section AA provides a closeup (see FIG. 3C) of a machined channel.
Section BB provides a closeup (see FIG. 3C) of a machined
articulated bridge.
[0036] FIG. 3C is a closeup of Section AA, which is a machined
channel, and Section BB, which is a machined articulated
bridge.
[0037] FIG. 4 is a very close-up sectioned view of stent element 28
(the remainder of stent 24 is not shown for clarity) as chronically
implanted. As shown, stent element 28 is channeled in the
longitudinal direction (i.e., direction of blood flow). Channel 30
is outwardly concave, as shown. This permits greater perfusion of
surface 36 of coronary artery 16. Furthermore, edges 32 and 34 tend
to prevent inadvertent repositioning during chronic
implantation.
[0038] FIG. 5 is a view similar to that shown in FIG. 6 with the
addition of medication 38 within channel 30. Medication 38 is
typically an anti-clotting agent, such as TPA, or an anti-irritant,
such as a suitable steroid. The placement of medication 38 within
channel 30 enhances chronic dispersion of the drug.
[0039] FIG. 6 is a view similar to FIG. 4, in which stent element
28 (the remainder of stent 24 is not shown for clarity) is
channeled laterally (i.e., perpendicular to the direction of blood
flow). Channel 44 is formed in the same manner as channel 30 (see
also FIG. 4), but it is machined perpendicularly. Channel 44, edge
40, and edge 42 function in the same manner as channel 30, edge 32,
and edge 34.
[0040] FIG. 7 is a view similar to FIG. 6 wherein channel 44
contains medication 38. This embodiment functions similar to the
embodiment of FIG. 5.
[0041] FIG. 8 is a view similar to FIG. 6 wherein channel 44 is
utilized to provide differential flexibility to stent element 28.
This differential flexibility is important in accommodating bend 46
of vessel 16. This differential flexibility also assists in
resisting inadvertent repositioning.
[0042] FIG. 9 is a view similar to FIG. 8 wherein channel 40 has
been machined deeply into stent element 28 and wherein the thin
region 48 in stent element 28 imparts a particular articulation in
stent 24.
[0043] Having thus described the preferred embodiments of the
present invention, those of skill in the art will readily
appreciate that the teachings found herein may be applied to yet
other embodiments within the scope of the claims hereto
attached.
* * * * *