U.S. patent application number 14/280441 was filed with the patent office on 2014-09-04 for apparatus for treating vulnerable plaque.
This patent application is currently assigned to Abbott Cardiovascular Systems Inc.. The applicant listed for this patent is Abbott Cardiovascular Systems Inc.. Invention is credited to Stephen Dirk Pacetti.
Application Number | 20140249475 14/280441 |
Document ID | / |
Family ID | 42314281 |
Filed Date | 2014-09-04 |
United States Patent
Application |
20140249475 |
Kind Code |
A1 |
Pacetti; Stephen Dirk |
September 4, 2014 |
APPARATUS FOR TREATING VULNERABLE PLAQUE
Abstract
Embodiments include a medical device having a balloon portion
with a first end, a second end, and a variable balloon mass to
inflate the balloon portion non-uniformly from the first end to the
second end. In one embodiment, the balloon portion inflates in a
controlled manner to rupture a vulnerable plaque near the second
end.
Inventors: |
Pacetti; Stephen Dirk; (San
Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Abbott Cardiovascular Systems Inc. |
Santa Clara |
CA |
US |
|
|
Assignee: |
Abbott Cardiovascular Systems
Inc.
Santa Clara
CA
|
Family ID: |
42314281 |
Appl. No.: |
14/280441 |
Filed: |
May 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11607768 |
Dec 1, 2006 |
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14280441 |
|
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10459171 |
Jun 10, 2003 |
7753926 |
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11607768 |
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Current U.S.
Class: |
604/96.01 ;
606/159 |
Current CPC
Class: |
A61B 17/22032 20130101;
A61M 2025/1097 20130101; A61M 29/02 20130101; A61M 25/10 20130101;
A61B 2017/22081 20130101; A61B 17/320725 20130101 |
Class at
Publication: |
604/96.01 ;
606/159 |
International
Class: |
A61B 17/3207 20060101
A61B017/3207; A61M 25/10 20060101 A61M025/10 |
Claims
1. A balloon catheter, comprising: a balloon portion having a
proximal end attached to the catheter, a distal end attached to the
catheter, and a variable balloon mass to result in said balloon
portion expanding non-uniformly from said proximal end to said
distal end during inflation, wherein said balloon portion is
adapted to rupture a vulnerable plaque in a blood vessel from said
proximal end to said distal end, wherein said balloon comprises at
least one internal member to shape the inflation profile of the
balloon.
2. The balloon catheter of claim 1, wherein said at least one
internal member is to result in the balloon inflating from a
non-inflated uniform diameter from the proximal end to the distal
end to have a diameter that tapers from the proximal end to the
distal end to rupture said vulnerable plaque near the distal
end.
3. The balloon catheter of claim 1, wherein said at least one
internal member is one of disk-shaped or spokes, is coupled to an
inner surface of said balloon, is disposed substantially
perpendicular to said tubular shape of said balloon, and is made of
an elastomeric material.
4. The balloon catheter of claim 3, wherein an expandable member
disposed near a distal end of said balloon is thicker relative to
an expandable member disposed near said proximal end.
5. The balloon catheter of claim 1, wherein said at least one
expandable member extends near said proximal end to near said
distal end and is coupled to an inner surface of said balloon.
6. The balloon catheter of claim 5, wherein said at least one
expandable member has a thickness that tapers from near said distal
end to near said proximal end.
7. The balloon catheter of claim 6, wherein three expandable
members are disposed equidistantly within said balloon.
8. The medical device of claim 7, wherein three balloon segments
are coupled to each other linearly and have an increasing wall
thickness from said proximal end to said distal end, and wherein
each of the three balloon segments has an independent inflation
lumen.
9. The medical device of claim 7, wherein three balloon segments
are coupled to each other linearly and have an increasing wall
thickness from said proximal end to said distal end, and wherein
said three balloon segments share a common inflation lumen.
10. The balloon catheter of claim 1 wherein the balloon is
configured to be inflated with an inflation medium, which is heated
to a temperature which is higher than a normal body
temperature.
11. The balloon catheter of claim 1 further comprising: a detector
coupled to said balloon portion, said detector for detecting a
vulnerable plaque; a drug lumen coupled to said balloon portion,
said drug lumen for releasing an anticoagulant as said balloon is
inflated; and a perfusion lumen coupled to said balloon portion,
said perfusion lumen for allowing blood to flow downstream from
said vulnerable plaque while said balloon is inflated.
12. A medical device, comprising: a catheter having a proximal
portion and a distal portion; and at least one balloon, disposed
near said distal portion, having a proximal end and a distal end,
wherein said at least one balloon is adapted to inflate from said
proximal end to said distal end to rupture a vulnerable plaque in a
blood vessel near said distal end, wherein said at least one
balloon comprises a middle portion and at least one internal member
to shape the inflation profile of the balloon to taper along an
inflatable length of the balloon from said distal end to said
middle portion and from said middle portion to said proximal
end.
13. The medical device of claim 12, wherein said at least one
internal member is to result in the balloon inflating from a
non-inflated uniform diameter from the proximal end to the distal
end to have a diameter that tapers from the proximal end to the
distal end to rupture said vulnerable plaque near the distal
end.
14. The medical device of claim 12, wherein said at least one
balloon has a tubular shape when inflated, and wherein said
catheter has at least one inflation lumen formed therein.
15. The medical device of claim 12, wherein said at least one
balloon, when non-inflated, has a folded configuration.
16. The medical device of claim 15, wherein said at least one
balloon, when non-inflated, has a diameter that tapers down from
said proximal end to said distal end, and wherein said at least one
balloon has a length of about 8 to 30 mm.
17. The medical device of claim 12, wherein said at least one
balloon is made of a compliant material comprising one of a high
durometer polyurethane, nylon, mylar, and Pebax.
18. The medical device of claim 12, wherein said at least one
expandable member is one of disk-shaped or spokes, is coupled to an
inner surface of said at least one balloon, is disposed
substantially perpendicular to said tubular shape of said at least
one balloon, and is made of an elastomeric material.
19. The medical device of claim 18, wherein an expandable member
disposed near a distal end of said at least one balloon is thicker
relative to an expandable member disposed near said proximal
end.
20. The medical device of claim 12, wherein said at least one
expandable member extends near said proximal end to near said
distal end and is coupled to an inner surface of said at least one
balloon.
21. The medical device of claim 20, wherein said at least one
expandable member has a thickness that tapers from near said distal
end to near said proximal end.
22. The medical device of claim 21, wherein three expandable
members are disposed equidistantly within said at least one
balloon.
23. The medical device of claim 22, wherein three balloon segments
are coupled to each other linearly and have an increasing wall
thickness from said proximal end to said distal end, and wherein
each of the three balloon segments has an independent inflation
lumen.
24. The medical device of claim 22, wherein three balloon segments
are coupled to each other linearly and have an increasing wall
thickness from said proximal end to said distal end, and wherein
said three balloon segments share a common inflation lumen.
25. A medical device, comprising: means for controlling the
inflation behavior of a balloon catheter; and means for treating a
vulnerable plaque, wherein means for controlling further comprises
means for inflating said balloon catheter non-uniformly from a
first end to a second end, wherein said balloon comprises at least
one internal member to shape the inflation profile of the
balloon.
26. The medical device of claim 25, wherein means treating further
comprises means for rupturing said vulnerable plaque in a direction
with a blood flow.
Description
RELATED APPLICATION
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 11/607,768 filed Dec. 1, 2006, which is a
divisional of U.S. patent application Ser. No. 10/459,171 filed
Jun. 10, 2003 entitled, "Method and Apparatus for Treating
Vulnerable Plaque", which issued as U.S. Pat. No. 7,753,926 on Jul.
13, 2010.
TECHNICAL FIELD
[0002] The invention, in one embodiment, relates generally to the
treatment of atherosclerosis such as heart related diseases, and
more particularly, in one embodiment, to the treatment of
vulnerable plaque.
BACKGROUND
[0003] Coronary heart disease is generally thought to be caused by
the narrowing of coronary arteries by atherosclerosis, the buildup
of fatty deposits in the lining of the arteries. The process that
may lead to atherosclerosis begins with the accumulation of excess
lipids and cholesterol in the blood. These substances infiltrate
the lining of arteries, gradually increasing in size to form
deposits commonly referred to as plaque or atherosclerotic
occlusions. Plaques narrow the arterial lumen and impede blood
flow. Thrombus can accumulate on the lesion, eventually creating a
blood clot that may block the artery completely.
[0004] The phenomenon of "vulnerable plaque" has created new
challenges in recent years for the treatment of heart disease.
Unlike occlusive plaques that impede blood flow, vulnerable plaque
develops within the arterial walls, but it often does so without
the characteristic substantial narrowing of the arterial lumen and
resulting symptoms. As such, conventional methods for detecting
heart disease, such as an angiogram, may not detect vulnerable
plaque growth into the arterial wall. After death, histological
examination of the heart can reveal the presence of intact and
ruptured vulnerable plaques in the coronary arteries.
[0005] The intrinsic histological features that may characterize a
vulnerable plaque include increased lipid content, increased
macrophage, foam cell and T-lymphocyte content, and reduced
collagen and smooth muscle cell ("SMC") content. This fibroatheroma
type of vulnerable plaque is often referred to as "soft," having a
large lipid pool covered by a fibrous cap. The fibrous cap contains
mostly collagen, whose reduced concentration combined with
macrophage derived enzyme degradation can cause the fibrous cap of
these lesions to rupture under unpredictable circumstances. When
ruptured, the lipid core contents, thought to include tissue
factor, contact the arterial bloodstream, cause a blood clot to
form that can completely block the artery resulting in an acute
coronary syndrome ("ACS") event. This type of atherosclerosis is
coined "vulnerable" because of the unpredictable tendency of the
plaque to rupture. It is thought that hemodynamic and cardiac
forces, which yield circumferential stress, shear stress, and
flexion stress, may cause disruption of a fibroatheroma type of
vulnerable plaque. These forces may rise as the result of simple
movements, such as getting out of bed in the morning, or in vivo
forces related to blood flow and the beating of the heart. It is
thought that plaque vulnerability in fibroatheroma types is
determined primarily by factors which include: (1) size and
consistency of the lipid core; (2) thickness of the fibrous cap
covering the lipid core; and (3) inflammation and repair within the
fibrous cap.
[0006] FIGS. 1A-1C illustrate the bursting of a vulnerable plaque
and the blockage of blood flow by the resulting scar tissue. FIG.
1A illustrates the growth of a vulnerable plaque within the vessel
wall. As is typical of vulnerable plaque, it does not extend far
out into the vessel lumen to obstruct blood flow (as indicated by
the directional arrows). FIG. 1B illustrates the rupturing of the
vulnerable plaque, and in this case, in a direction against blood
flow. This event alone may cause an occlusive thrombosis.
Alternatively, the ruptured contents may be washed downstream by
the blood flow (if the ruptured contents are relatively small)
without any harmful effects. However, as illustrated by FIG. 1C,
the fibrous cap that remains as dissected edges, and torn flaps,
can protrude into the blood flow, or even form pockets that further
increase the chances of an occlusive clot formation. The interior
lining of the fibrous cap, and lipid pool, has no coverage of
endothelial cells. In addition to mechanical obstructions, all of
these surfaces are highly thrombogenic. As such, the therapeutic
rupture of a vulnerable plaque might be a viable treatment method
if not for the uncontrolled mechanics of the rupture, exposing
thrombogenic surfaces, creating issue flaps and dissection, and
even forming occlusive pockets. The prior art does not provide for
a device or technique to treat vulnerable plaque by rupturing it in
a controlled manner while minimizing harmful side effects.
SUMMARY
[0007] Embodiments of a medical device having a balloon portion
with a first end, a second end, and a variable balloon mass to
inflate the balloon portion non-uniformly from the first end to the
second end are described. In one embodiment, the balloon portion
inflates in a controlled manner to rupture a vulnerable plaque near
the second end. In an alternative embodiment, at least one balloon
is disposed near a distal portion of a catheter. The balloon
inflates from a proximal end to a distal end to rupture a
vulnerable plaque near the distal end and in the direction of blood
flow.
[0008] Additional embodiments, features, and advantages of the
medical device will be apparent from the accompanying drawings, and
from the detailed description that follows below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention may best be understood by referring to the
following description and accompanying drawings that are used to
illustrate embodiments of the invention. In the drawings:
[0010] FIGS. 1A-1C illustrate the bursting of a vulnerable plaque
and the downstream blockage of blood flow.
[0011] FIG. 2A illustrates one embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0012] FIG. 2B illustrates one embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0013] FIG. 2C illustrates one embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0014] FIG. 2D illustrates one embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0015] FIG. 3 illustrates one embodiment of a medical device that
may be used to control the bursting of a vulnerable plaque.
[0016] FIG. 3A illustrates a proximal portion of the medical device
shown in FIG. 3.
[0017] FIG. 3B illustrates a distal portion of the medical device
shown in FIG. 3.
[0018] FIG. 3C illustrates a cross-sectional view taken along line
A-A of the medical device shown in FIG. 3B.
[0019] FIG. 3D illustrates a cross-sectional view taken along line
B-B of the medical device shown in FIG. 3B.
[0020] FIG. 3E illustrates a cross-sectional view taken along line
C-C of the medical device shown in FIG. 3B.
[0021] FIG. 3F illustrates a cross-sectional view taken along line
D-D of the medical device shown in FIG. 3B.
[0022] FIG. 4A illustrates one embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0023] FIG. 4B illustrates one embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0024] FIG. 5A illustrates a cross-sectional view of the balloon
catheter shown in FIGS. 4A-4B.
[0025] FIG. 5B illustrates a cross-sectional view of the balloon
catheter shown in FIGS. 4A-4B.
[0026] FIG. 6A illustrates an alternative cross-sectional view of
the balloon catheter shown in FIGS. 4A-4B.
[0027] FIG. 6B illustrates an alternative cross-sectional view of
the balloon catheter shown in FIGS. 4A-4B.
[0028] FIG. 7A illustrates another embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0029] FIG. 7B illustrates another embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0030] FIG. 7C illustrates another embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0031] FIG. 8A illustrates another embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0032] FIG. 8B illustrates another embodiment of a balloon catheter
that may used for the controlled bursting of a vulnerable
plaque.
[0033] FIG. 9 illustrates a cross-sectional view of the balloon
catheter shown in FIGS. 8A-8B.
[0034] FIG. 10A illustrates another embodiment of a balloon
catheter that may be used for the controlled bursting of a
vulnerable plaque.
[0035] FIG. 10B illustrates another embodiment of a balloon
catheter that may be used for the controlled bursting of a
vulnerable plaque.
[0036] FIG. 11A illustrates a cross-sectional view taken along line
A-A of the balloon catheter shown in FIGS. 10A-10B.
[0037] FIG. 11B illustrates a cross-sectional view taken along line
B-B of the balloon catheter shown in FIGS. 10A-10B.
[0038] FIG. 11C illustrates a cross-sectional view taken along line
C-C of the balloon catheter shown in FIGS. 10A-10B.
[0039] FIG. 12A illustrates another embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0040] FIG. 12B illustrates another embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0041] FIG. 12C illustrates another embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0042] FIG. 12D illustrates another embodiment of a method for the
controlled bursting of a vulnerable plaque.
[0043] FIG. 13 illustrates another embodiment of a medical device
that may be used to control the bursting of a vulnerable
plaque.
[0044] FIG. 13A illustrates a proximal portion of the medical
device shown in FIG. 13.
[0045] FIG. 13B illustrates a distal portion of the medical device
shown in FIG. 13.
[0046] FIG. 14A illustrates a cross-sectional view taken along line
A-A of the balloon catheter shown in FIG. 13B.
[0047] FIG. 14B illustrates a cross-sectional view taken along line
B-B of the balloon catheter shown in FIG. 13B.
[0048] FIG. 14C illustrates a cross-sectional view taken along line
C-C of the balloon catheter shown in FIG. 13B.
[0049] FIG. 14D illustrates a cross-sectional view taken along line
D-D of the balloon catheter shown in FIG. 13B.
[0050] FIG. 15 illustrates another embodiment of a medical device
that may be used to control the bursting of a vulnerable
plaque.
DETAILED DESCRIPTION
[0051] In the following description, numerous specific details are
set forth such as examples of specific components, processes, etc.
in order to provide a thorough understanding of various embodiments
of the present invention. It will be apparent, however, to one
skilled in the art that these specific details need not be employed
to practice various embodiments of the present invention. In other
instances, well known components or methods have not been described
in detail in order to avoid unnecessarily obscuring various
embodiments of the present invention. The term "coupled" as used
herein means connected directly to or indirectly connected through
one or more intervening components, structures or elements.
[0052] Apparatuses and methods for treating vulnerable plaque are
described. In one embodiment of the present invention, a vulnerable
plaque is ruptured in a controlled manner. Embodiments of the
present invention also include a medical device that provides
percutaneous treatment for vulnerable plaque. Embodiments of the
present invention prevent dissections and torn tissue flaps from
blocking blood flow, while minimizing the exposure of thrombogenic
surfaces, after the vulnerable plaque has been ruptured. In one
embodiment of the present invention, a medical device in the form
of a balloon catheter, disposed along a length of a vulnerable
plaque, inflates in a controlled manner from a proximal end towards
the distal end, and in the same direction of the blood flow. This
causes the vulnerable plaque to rupture towards the distal end of
the balloon and fibrous cap, and consequently in the same direction
as the blood flow. In doing so, the fibrous cap is preferentially
ruptured at its distal edge, or side edges. As such, one embodiment
of the medical device described herein provides the advantage of
controlling the point at which the contents of a vulnerable plaque
are squeezed out, or released into the bloodstream. Furthermore,
torn tissue flaps, dissections, or vulnerable plaque tissue (e.g.,
plaque cap) may not form in a manner that will obstruct blood flow
at the treatment site. Treatment of a vulnerable plaque with a
percutaneous balloon catheter can also cause lipid redistribution
external to the blood vessel. In one embodiment of the present
invention, the balloon catheter may be advanced percutaneously to
the target vulnerable plaque to avoid the need for invasive
surgery. In another embodiment, the balloon portion of the catheter
is strong and reliable under varying amounts of pressure and is
also capable of forming a variety of expandable shapes.
[0053] FIGS. 2A-2D illustrate cross-sectional views of one
embodiment of a medical device that may control the bursting of a
vulnerable plaque into the bloodstream. FIG. 2A illustrates
arterial wall 206 that forms a lumen 205 for blood flow in the
direction of the arrows indicated. Vulnerable plaque 225 has formed
within arterial wall 206 with plaque cap 230 facing arterial lumen
205. In one embodiment, the medical device is a balloon catheter
having catheter portion 215 and balloon 216. The balloon 216 has a
proximal end 217 and distal end 218. Balloon 216 is positioned
along a length of vulnerable plaque 225. Proximal end 217 of
balloon 216 is shown slightly inflated to form a tapered shape from
proximal end 217 to distal end 218. FIG. 2B illustrates proximal
end 217 of balloon 216 substantially inflated that causes
vulnerable plaque 225 to be pushed toward distal end 218 of balloon
216. FIG. 2C shows balloon 216 completely inflated from its
proximal end 217 to its distal end 218. Vulnerable plaque 225 has
now been squeezed toward distal end 218 of balloon 216. The
pressure formed in vulnerable plaque 225 by inflating balloon 216
causes vulnerable plaque 225 to rupture. Particularly, vulnerable
plaque 225 has ruptured into arterial lumen 205 near distal end 218
of balloon 216, in a direction with the blood flow. FIG. 2D shows
arterial lumen 205 with the balloon catheter removed. What remains
of the vulnerable plaque is the remnants of the fibrous cap, here
shown in cross section. Because the vulnerable plaque lipid core
was squeezed out at primarily the distal edge of the lesion, tissue
tears are limited to this area, and the rest of the plaque cap is
largely intact. As such, the plaque cap is less likely to obstruct
blood flow. If the vulnerable plaque were ruptured in an
uncontrolled, random manner, the fibrous cap can be torn into
tissue flaps or form a pocket that obstructs blood flow.
[0054] Various techniques may be utilized to detect the presence
and location of vulnerable plaque. For example, an ultrasound probe
("IVUS") or an optical coherence tomography probe ("OCT") may be
guided through the arteries to scan for vulnerable plaque.
Alternatively, magnetic resonance imaging ("MRI") devices may be
able to detect vulnerable plaque. Near Infrared spectroscopy is
another technique for detecting vulnerable plaque. For example,
certain wavelengths of light penetrate the arterial wall and
produce a specific chemical signature that could correlate to
vulnerable plaque composition. Additionally, thermography may also
be used to detect vulnerable plaque. Plaques that rupture tend to
be inflamed, and data indicates this correlates to a higher
temperature compared to non-vulnerable type plaques that do not
rupture. As such, a temperature sensitive probe that measures the
temperature of arteries could indicate the presence of vulnerable
plaque. Alternatively, liquid crystal thermography methods may also
be used. For example, a balloon material made of a thermochromic
liquid crystal material may be able to optically detect property
changes when exposed to increases in temperature. When the balloon
contacts a vulnerable plaque, the higher temperature of the
vulnerable plaque may be detected by analyzing a beam of light
directed towards the suspected vulnerable plaque region and the
balloon material in contact therewith. The light may undergo a
color change in the balloon material as a result of the higher
temperature. Any one of these detectors of vulnerable plaque may be
integrated into a catheter such as the device shown in FIGS. 2A-2D
or other embodiments described herein.
[0055] FIG. 3 illustrates a perspective view of one embodiment of
the present invention that may be used to rupture the vulnerable
plaque in a controlled manner. In one embodiment, the present
invention is a percutaneous medical device in the form of a balloon
catheter 300. Balloon catheter 300 has a proximal portion 305, a
distal portion 310, and an elongated catheter portion 315. FIG. 3A
shows an enlarged view of proximal portion 305 having a port 330
that leads to an inflation lumen 332. An opening 341 may be formed
by an inner wall 342 to form a guidewire lumen 340. A catheter wall
316 may be formed around inflation lumen 332 and guidewire lumen
340. FIG. 3B shows an enlarged view of distal portion 310 having
catheter wall 316 that forms inflation lumen 332 with inner wall
342. Inner wall 342 also forms guidewire lumen 340. Inflatable
balloon 350 may be disposed near distal portion 310 with a proximal
end 352 coupled to catheter wall 316 and distal end 354 coupled to
inner wall 342. Inflation lumen 332 is continuous from port 330
near a proximal portion 305 all the way to balloon 350 near distal
portion 310. As such, balloon 350 may be inflated by injecting an
inflation medium (e.g., a liquid or a gas) into port 330. The
inflation medium may be slightly heated relative to normal body
temperatures in order to liquefy the lipids in the vulnerable
plaque; in one example, the inflation medium may be heated to about
104.degree. F.
[0056] FIGS. 3C-3F illustrate various cross-sectional views of
distal portion 310. FIG. 3C shows a cross-sectional view of distal
portion 310 taken along line A-A. This region of balloon catheter
300 has catheter wall 316, inflation lumen 332, inner wall 342, and
guidewire lumen 340. FIG. 3D shows a cross-sectional view of
balloon catheter 300 taken along line B-B. This region of balloon
catheter 300 has balloon 350, inflation lumen 332, catheter wall
316, inner wall 342, and guidewire lumen 340. FIG. 3E shows a
cross-sectional view of balloon catheter 300 taking along line C-C.
This region of balloon catheter 300 has balloon 350, inflation
lumen 332, inner wall 342, and guidewire lumen 340. FIG. 3F shows a
cross-sectional view of balloon catheter 300 taking along line D-D.
This region of balloon catheter 300 has inner wall 342 and
guidewire lumen 340. In one embodiment, inner wall 342 and
guidewire lumen 340 extend from a proximal portion 305 to distal
portion 310.
[0057] In one embodiment of the present invention, balloon catheter
300 may be sized for percutaneous delivery through a blood vessel
for advancement to the arterial region (e.g., a coronary artery.)
In an alternative embodiment, balloon catheter 300 may be sized for
percutaneous delivery to other parts of the human body. In yet
another embodiment, a guidewire (not shown) may be initially
advanced to the treatment location. Catheter 300 may be loaded and
tracked over the guidewire (within guidewire lumen 340) to be
positioned near the vulnerable plaque. In other embodiments,
catheter 300 may be any of the catheter types used in the art,
including but not limited to "rapid exchange" (RX) catheters,
"over-the-wire" (OTW) catheters, or a "tip RX" catheters. If a
guidewire is utilized, the guidewire may be removed after the
distal portion 310 of catheter 300 has reached the target
vulnerable plaque. The catheter may, in certain embodiments,
include a drug lumen which is continuous from a proximal port to an
opening at a distal portion of the catheter. This drug lumen may be
used to release heparin or other anticoagulants downstream of the
balloon as the balloon is inflated. This will tend to prevent the
ruptured contents of the vulnerable plaque from causing a
thrombosis. Alternatively, the guidewire lumen may be used as a
drug lumen (e.g., after the guidewire is removed from the lumen.)
The catheter may also include, in certain embodiments, a perfusion
lumen which is coupled to the balloon and which allows blood to
flow downstream from the vulnerable plaque while the balloon is
inflated.
[0058] The catheter assembly can be formed from conventional
materials of construction. The material forming the catheter body
can be any metal or polymer with ductile properties which would be
acceptable for the needs of intravascular devices. Specifically,
the material chosen for the catheter body should have sufficient
flexibility so it can be easily advanced through tortuous
anatomy.
[0059] FIGS. 4A and 4B illustrate one embodiment of the present
invention in which a distal portion 310 of the balloon catheter has
a balloon 350 that inflates non-uniformly such that the proximal
end 352 inflates first, followed by the distal end 354. In one
embodiment, distal portion 310 may be part of balloon catheter 300
described above with respect to FIG. 3. Distal portion 310 has
catheter wall 316, inflation lumen 332, inner wall 342, and
guidewire lumen 340. Balloon 350 has a proximal end 352 coupled to
catheter wall 316 and a distal end 354 coupled to inner wall 342.
FIG. 4A shows balloon 350 having a wall thickness that tapers from
proximal end 352 towards distal end 354, that is, the thickness of
the balloon wall reduces along the balloon length from the proximal
end 352 to the distal end 354. Additionally, balloon 350 is molded
such that the overall shape of balloon 350 tapers from the proximal
end 352 to the distal end 354. As balloon 350 begins to inflate the
proximal end 352 inflates first to reach a size as dictated by its
material properties. Furthermore, the thickness of balloon 350 near
proximal end 352 limits the diameter and size to which it can
expand. As the pressure continues to increase with the addition of
more and more inflation medium, the distal end 354 of balloon 350
begins to expand to form the fully inflated form of balloon 350 as
illustrated in FIG. 4B. This design of a balloon that inflates from
proximal to distal requires a balloon with a larger proximal than
distal diameter at rest, a thicker balloon wall near proximal end
354, and a balloon material with low to medium compliance.
[0060] In one embodiment of the present invention, balloon 350 may
be made of elastomeric or compliant material including, but not
limited to, nylon 12, nylon 6, nylon 6.6, polyether-block
copolyamide polymers ("Pebax.RTM."), poly(ethylene terephthalate)
(Mylar.RTM.), polyethylene, polypropylene, polyether urethanes,
polycarbonate urethanes, polyester urethanes, silicone urethanes,
and polyesters (Hytrel.RTM.). In one embodiment, balloon 350 may
have a length in the range of 8-30 mm. Varying the distribution of
balloon mass from one end to the other may be achieved by a number
of methods known in the art. Balloon wall thickness may be made
variable (for example, tapered from a proximal end to a distal end)
by an extrusion process. Alternatively, a balloon wall thickness
may be varied by injection molding. Other methods are known in the
art; however, a detailed description is not provided herein.
[0061] FIGS. 5A and 5B show cross-sectional views of a balloon in a
non-inflated state and a fully inflated state, respectively. To
minimize the overall profile of balloon 350 in the non-inflated
state, balloon 350 may be folded into a particular pattern. FIG. 5A
shows one embodiment of a tri-fold pattern that balloon 350 may
have in the non-inflated state. This portion of the balloon has
balloon 350, inner wall 342, and guidewire lumen 340. When the
fully inflated, as shown in FIG. 5B, the folded balloon portions
expand into a substantially circular shape with balloon 350,
inflation lumen 332, inner wall 342, and guidewire lumen 340.
Although present, inflation lumen 332 is not shown in the
non-inflated state of FIG. 5A.
[0062] FIGS. 6A and 6B show cross-sectional views of an alternative
embodiment of a folded pattern for a balloon in a non inflated
state. In this embodiment balloon 350 forms a bi-fold (twofold
instead of three as shown with respect to FIG. 5A). As shown in
FIG. 6A the folded configuration has balloon 350 inner wall 342,
and guidewire lumen 340. In the fully inflated state as illustrated
in FIG. 6B, the balloon portion expands to form the same
substantially circular shape as illustrated in FIG. 5B. In the
inflated state, balloon portion has balloon 350, inflation lumen
332, inner wall 342, and guidewire lumen 340.
[0063] FIGS. 7A-7C illustrate cross-sectional views of another
embodiment of a medical device that may be used to rupture in a
controlled manner. FIG. 7A illustrates a balloon catheter portion
410 in a non-inflated state in which proximal end 452 may have
substantially uniform diameter as distal end 454. In the
non-inflated state, balloon catheter portion 410 maintains a low
profile for advancement through a tortuous anatomy. Balloon
catheter 410 includes catheter portion 416 that is coupled to the
proximal end 452 of balloon 450. An inner wall 442 may form a
guidewire lumen 440 within catheter 416. An inflation lumen 432 may
also be formed between catheter 416 and inner wall 442. In this
embodiment, the thickness of balloon 450 tapers from the distal end
454 to the proximal end 452. In one embodiment, balloon 450 may be
made of a highly elastomeric or high compliant material.
Alternatively, proximal end 452 may be composed of high durometer
polyurethane or another suitable thermoplastic elastomer such as
Pebax.RTM., Hytrel.RTM., and Kraton.RTM.. The stress-strain
behavior of an elastomer includes an ultimate strain where further
elongation stops. This physical property of balloon 450, coupled
with the greater distal wall thickness than the proximal wall
thickness, results in a balloon 450 which inflates from the
proximal end 452 to the distal end 454. In one embodiment, balloon
catheter 410, as illustrated, may be part of a medical device in
which the balloon catheter portion 410 is the distal portion of an
elongated catheter with a proximal portion having input ports, for
example, as illustrated in FIG. 3.
[0064] FIG. 7B illustrates balloon catheter 410 in a partially
inflated state. As an inflation medium is delivered through
inflation lumen 432, the proximal end 452 of balloon 450 inflates
first. Proximal end 452 of balloon 450 inflates to a predetermined
size or diameter based on the material, and the lesser wall
thickness of balloon 450 near proximal end 452. FIG. 7C illustrates
both proximal end 452 and distal end 454 of balloon 450 fully
inflated to a substantially uniform size or diameter. As discussed
above, because a thickness of balloon 450 near distal end 454 is
greater than proximal end 452, distal end 454 will inflate last.
This produces the effect as described with FIGS. 2A-2D (with the
vulnerable plaque undergoing rupture near distal end 454).
[0065] FIGS. 8A and 8B illustrate another embodiment of a medical
device for rupturing the vulnerable plaque in a controlled manner
with an inflatable balloon. FIG. 8A shows a distal portion of a
balloon catheter 510 with inflatable balloon 550 disposed on
catheter 516. Catheter 516 includes a guidewire lumen 540 formed by
an inner catheter wall or tube 542. An inflation lumen 532 may be
formed between catheter 516 and inner catheter portion 542. Balloon
550 may have one or more internal members (e.g., 560, 562) to
control the elastic resistance of balloon 550. In one embodiment,
the elastic members may be elastomeric disk shaped members that
extend from a surface of catheter 516 to an inner surface of
balloon 550. For example, a first member 560 may be disposed near a
central portion 555 of balloon 550, and a second member 562 may be
disposed near a distal portion 554 of balloon 550. The internal
members form inflation chambers 533, 534, and 535 within balloon
550. First member 560 may have a thickness that is less than the
second member 562. Because of the difference in thickness between
members 560 and 562, each member may exhibit varying compliance
properties. In other words, first member 560 may expand with less
pressure applied as compared to second member 562. As such, when an
inflation medium is delivered to balloon 550, proximal portion 552
will expand first followed by a central portion 555, and distal
portion 554 expanding last. The material properties and thickness
of balloon 550 may determine the size and diameter to which balloon
550 fully expands.
[0066] FIG. 8B illustrates balloon 550 in a fully inflated state.
As discussed above, the varying thickness of internal members 560
and 562 disposed within balloon 550 determines the inflation
behavior from proximal portion 552 to distal portion 554. This
produces the effect discussed above with respect to FIGS. 2A-2D to
rupture the vulnerable plaque in a controlled manner. In one
embodiment, inflated balloon 550 may have a substantially
cylindrical shape. In an alternative embodiment, balloon 550 may
have other shapes.
[0067] FIG. 9 illustrates a cross-sectional view of balloon 550
taken along line A-A through first internal member 560. In one
embodiment, internal member 560 may be disk-shaped such that
internal member 560 makes continuous contact with an inner surface
of balloon 550. If the internal members are not solid discs, then
chambers 533, 534, and 535 would be in communication with each
other and inner tubular member 516 need only extend past the
proximal attachment of the balloon. An inflation lumen is formed
between catheter 516 and inner wall 542. A guidewire lumen 540 may
also be formed by inner catheter 542. The internal members are not
limited or restricted to disk shaped structures. It may be
appreciated by one of skill in the art that other structural shapes
may be used for the internal members. For example, the internal
members may be a series of spokes (not shown) disposed around
catheter 516 within balloon 550. In another embodiment, alternative
structures may be used.
[0068] FIG. 10A illustrates an alternative embodiment of a balloon
catheter that inflates from a proximal portion towards the distal
portion for controlling the bursting of a vulnerable plaque. FIG.
10A illustrates a partial see-through view of balloon catheter
portion 610. An inflatable balloon 650 is disposed over catheter
616 with proximal portion 652 and distal portion 654 of balloon 650
coupled to catheter 616. An internal member 660 extends from
proximal portion 652 to distal portion 654 of balloon 650. In one
embodiment of the present invention, internal member 616 does not
extend into the shoulder regions of balloon 650. A thickness 653 of
internal member 660 increases from a proximal end 661 towards
distal end 662. Internal member 660 also extends from a surface of
catheter 616 towards an inner surface of balloon 650. In one
embodiment, internal member 660 may be made of an elastomeric
material. As such, because proximal end 661 is thinner than distal
end 662, balloon 650 inflates first near proximal portion 652 when
an inflation medium is injected through an inflation lumen (not
shown) to inflate balloon 650. It should be noted that for clarity
of description only one internal member is illustrated. However, in
alternative embodiments, multiple internal members may be disposed
within balloon 650. In one alternative embodiment, 3 internal
members may be disposed within balloon 650, spaced approximately
120 degrees around catheter 616.
[0069] FIG. 10B illustrates a top view of balloon catheter portion
610 described above with respect to FIG. 10A. As illustrated in
this partial see-through view, internal member 660 extends along a
length of balloon 650 from the proximal portion 652 towards the
distal portion 654. A thickness of internal member 660 increases
from the proximal end 661 towards the distal end 662. A topside or
surface of internal member 660 is coupled to an inner surface of
balloon 650 and a bottom surface of internal member 660 is coupled
to a surface of catheter 616.
[0070] FIGS. 11A-11C illustrated cross-sectional views of balloon
catheter 610 described above with respect to FIGS. 10A and 10B.
FIG. 11A shows a cross-sectional view taken along line A-A of
balloon 650 in an un-inflated state. Balloon 650 includes 3
internal members 665, 666, and 667 disposed approximately 120
degrees apart from each other around catheter 616 disposed within
balloon 650. A bottom surface of each internal member is coupled to
catheter 616, and a top surface is coupled to an inner surface of
balloon 650. An inflation lumen 632 is formed between catheter 616
and inner catheter 642 for passing an inflation medium (e.g., a gas
or a liquid) into balloon 650. A guidewire lumen 640 may be formed
by inner catheter 642 for passing a guidewire therein.
[0071] FIGS. 11B and 11C illustrate cross-sectional views of
inflated balloon 650 near proximal portion 652 and distal portion
654, respectively. FIG. 11B shows a cross-sectional view of balloon
650 taken along line B-B. Balloon 650 has inflated to a
substantially round shape with internal members 665, 666, and 667
expanded radially from catheter 616. A thickness of each internal
member is thin compared to the thickness near distal portion 654 as
illustrated by FIG. 11C, which shows a cross-sectional view taken
along line C-C. In one embodiment, the thickness of the internal
members gradually increases from the proximal end 661 to the distal
end 662. This variable thickness causes the proximal portion 652 of
balloon 650 to inflate first followed by the distal portion 654.
When disposed near a targeted vulnerable plaque, balloon 650
inflates to force the vulnerable plaque to burst near the distal
portion 654 and in a direction downstream with the blood flow. As
discussed above, this controlled rupture minimizes the formation of
residual tissue flaps or pockets that may obstruct blood flow after
the vulnerable plaque has been drained.
[0072] FIGS. 12A-12D illustrate an alternative embodiment of a
medical device that ruptures a vulnerable plaque along its distal
margin and in a direction of blood flow. A percutaneous medical
device in the form of a catheter includes multiple balloons
disposed near a distal end. The balloons may be disposed in a
linear fashion and allowed to inflate in a particular order. For
example, a catheter 715 may have three balloons 716, 717, and 718
disposed linearly along the catheter shaft. To treat a vulnerable
plaque 725 that has developed within a blood vessel wall 706,
catheter 715 is advanced within the blood lumen 705 such that a
proximal portion 720 and prevents the vulnerable plaque 725, from
forming tissue flaps, tears, and pockets that obstruct blood flow.
Next, as illustrated in FIG. 12B, balloon 716 disposed near
proximal portion 720 is inflated first. The inflation of balloon
716 pushes or squeezes vulnerable plaque 725 towards distal portion
730. Next, as illustrated in FIG. 12C, the inflation of balloon 717
continues to push vulnerable plaque 725 towards distal portion 730.
FIG. 12D illustrates the inflation of balloon 718 that causes the
buildup of enough pressure within vulnerable plaque 725 to cause
its rupture. The sequential inflation from balloons 716 to 718
results in vulnerable plaque 725 rupturing in a direction
consistent with the blood flow (as indicated by the arrows), and
prevents the vulnerable plaque 725 from forming scar tissue that
obstructs blood flow.
[0073] FIG. 13A illustrates a perspective view of a balloon
catheter for controlling the rupturing of the vulnerable plaque as
described above with respect to FIGS. 12A-12D. Catheter 800
includes a proximal portion 805, an elongated shaft portion 802,
and a distal portion 810. Proximal portion 805 has one or more
inflation ports for independently inflating balloons disposed near
proximal portion 810. For example, catheter 800 may have three
inflation ports 806, 807, and 808 for inflating balloons 816, 817,
and 818. A guidewire port 809 may also be disposed near proximal
portion 805 for inserting a guidewire within shaft portion 802 into
the balloons disposed near distal portion 810. In one embodiment,
catheter 800 may be sized for percutaneous delivery through a blood
vessel for advancement to the arterial region. In an alternative
embodiment, catheter 800 may be sized for percutaneous delivery to
other parts of the human body. Although catheter 800 illustrates
three inflation ports corresponding to three balloons, it may be
appreciated that any number of balloons may be disposed near distal
portion 810, each having a corresponding inflation port.
Alternatively, more than one balloon may be inflated by a single
inflation port.
[0074] FIG. 13A illustrates an enlarged view of proximal portion
805 of catheter 800 shown in FIG. 13. An inflation port 806 leads
to inflation lumen 830, port 807 leads to inflation lumen 832, and
inflation port 808 leads to inflation lumen 834. A guidewire lumen
840 may also be formed within a center of proximal portion 805.
FIG. 13B illustrates an enlarged view of a distal portion 810 of
catheter 800 shown in FIG. 13. Balloons 816, 817, and 818 extend
from catheter shaft portion 802. Each balloon and has its own
inflation lumen with inflation lumen 830 extending into balloon
816, inflation lumen 832 extending into balloon 817, and inflation
lumen 834 extending into balloon 818. Also, guidewire lumen 840
extends within all three balloons and past distal balloon 818. As
such, to rupture a vulnerable plaque as illustrated in FIGS.
12A-12D, an inflation medium is inserted first through port 806 and
through lumen 830 to inflate balloon 816. Next, inflation medium is
inserted into port 807 through lumen 832 to inflate balloon 817.
Lastly, inflation medium is inserted through port 808 and through
lumen 834 to inflate balloon 818.
[0075] FIGS. 14A-14D illustrate various cross-sectional views of
distal portion 810 as discussed above with respect to FIG. 13B.
FIG. 14A illustrates a cross-sectional view taken along line A-A
showing balloon 816, inflation lumen 830, inflation lumen 832,
inflation lumen 834, and guidewire lumen 840. FIG. 14D illustrates
a cross-sectional view taken along line B-B showing balloon 817,
inflation lumen 832, inflation lumen 834, and guidewire lumen 840.
FIG. 14C illustrates a cross-sectional view taken along line C-C
showing balloon 818, inflation lumen 834, and guidewire lumen 840.
FIG. 14D illustrates a cross-sectional view taken along line D-D
showing catheter shaft portion 802 and guidewire lumen 840. In an
alternative embodiment, balloons 816, 817, and 818 may have a
common inflation lumen and still be inflated in a particular order
(e.g., by controlling the rate at which the inflation medium is
passed into the balloons).
[0076] FIG. 15 illustrates a view of an alternative embodiment of a
multi-balloon catheter for controlling the rupture of a vulnerable
plaque. A distal portion 910 may have three balloons 916, 917, and
918, with balloon 916 as the most proximal balloon and balloon 918
being the most distal balloon. Each balloon may have a
predetermined thickness, for example, with balloon 916 having a
thickness 926, balloon 917 having a thickness 927, and balloon 918
having a thickness 928. The thickness of each balloon increases
distally from balloon 916 towards balloon 918. It should be noted
that the relative thickness as shown in FIG. 15 may be exaggerated
for the purpose of describing the structural properties of distal
portion 910. As inflation medium is passed into the three balloons,
balloon 916 inflates first followed by balloon 917 with balloon 918
inflating last. In one embodiment, balloons 916, 917, and 918 may
be made of elastomeric or compliant materials, including but not
limited to, Pebax.RTM., Mylar.RTM., Hytrel.RTM., and Kraton.RTM..
In an alternative embodiment, other polymers may be used.
[0077] In the foregoing specification, a medical device has been
described with reference to specific exemplary embodiments thereof.
For example, the medical device may be used to treat other diseased
sites including occluded vascular grafts or heart valves. It will,
however, be evident that various modifications and changes may be
made thereto without departing from the broader spirit and scope of
the medical device as set forth in the appended claims. The
specification and figures are, accordingly, to be regarded in an
illustrative rather than a restrictive sense.
* * * * *