U.S. patent application number 09/909419 was filed with the patent office on 2002-03-21 for aspiration catheter.
Invention is credited to Bagaoisan, Celso J., Ha, Hung V., Lam, Sivette, Patel, Mukund R..
Application Number | 20020035347 09/909419 |
Document ID | / |
Family ID | 34080932 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020035347 |
Kind Code |
A1 |
Bagaoisan, Celso J. ; et
al. |
March 21, 2002 |
Aspiration catheter
Abstract
Aspiration catheters suitable for use in the treatment of an
occlusion in a blood vessel are disclosed. These catheters are
especially useful in the removal of occlusions from saphenous vein
grafts, the coronary and carotid arteries, arteries above the
aortic arch and even smaller vessels. The catheters of the present
invention are provided in either over-the-wire or in single
operator form. Radiopaque markers are preferably incorporated into
distal ends of the catheters to facilitate their positioning within
the body. The catheters are provided with varying flexibility along
the length of the shaft, such that they are soft and flexible
enough to be navigated through the vasculature of a patient without
causing damage, but are stiff enough to sustain the axial push
required to position the catheter properly and to sustain the
aspiration pressures.
Inventors: |
Bagaoisan, Celso J.; (Union
City, CA) ; Ha, Hung V.; (San Jose, CA) ;
Patel, Mukund R.; (San Jose, CA) ; Lam, Sivette;
(San Jose, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
620 NEWPORT CENTER DRIVE
SIXTEENTH FLOOR
NEWPORT BEACH
CA
92660
US
|
Family ID: |
34080932 |
Appl. No.: |
09/909419 |
Filed: |
July 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09909419 |
Jul 18, 2001 |
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09454522 |
Dec 6, 1999 |
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09454522 |
Dec 6, 1999 |
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08813808 |
Mar 6, 1997 |
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Current U.S.
Class: |
604/35 ;
604/41 |
Current CPC
Class: |
A61M 2025/1052 20130101;
A61M 2025/109 20130101; A61M 25/1011 20130101; A61M 2025/1015
20130101; A61M 2025/1093 20130101 |
Class at
Publication: |
604/35 ;
604/41 |
International
Class: |
A61M 001/00 |
Claims
What is claimed is:
1. An aspiration catheter, comprising an elongate flexible tubular
body having a proximal end and a distal end; a main lumen extending
through the tubular body; an aspiration port at the proximal end of
the tubular body, the aspiration port being in fluid communication
with the main lumen; and a tip on the distal end of the tubular
body, the tip being formed of a more flexible material than that
used to form the tubular body.
2. The catheter of claim 1, further comprising a reinforcement
incorporated into at least a portion of said tubular body.
3. The catheter of claim 2, wherein said reinforcement is selected
from the group consisting of a metallic braid, a polymer coil, and
a metallic coil.
4. The catheter of claim 2, wherein the reinforcement is formed of
a material selected from the group consisting of a polymer,
stainless steel, ELGILOY, silver plated stainless steel, gold
plated stainless steel, platinum, nitinol, or a combination
thereof.
5. The catheter of claim 1, wherein the distal end of the tubular
body is more flexible than the proximal end of the tubular
body.
6. The catheter of claim 5, wherein the tubular body has a braid
density or coil pitch at the distal end equal to or greater than
the density or pitch at the proximal end.
7. The catheter of claim 1, wherein the main lumen is sized to
receive at least one separate catheter which is slidably disposed
therein.
8. The catheter of claim 1, wherein the main lumen has an inner
diameter of approximately 0.045".
9. The catheter of claim 1, further comprising a second lumen
adjacent said first lumen adapted to receive a guidewire
therethrough.
10. The catheter of claim 9, wherein said second lumen extends
substantially the entire length of the tubular body.
11. The catheter of claim 9, wherein said second lumen extends less
than about 40 cm in a proximal direction from the distal end of the
tubular body.
12. The catheter of claim 9, wherein said second lumen has a slit
through a side wall of the lumen to allow insertion and removal of
the guidewire therethrough.
13. The catheter of claim 9, wherein said second lumen has an inner
diameter of approximately 0.020".
14. The catheter of claim 1, wherein said distal tip of said
catheter comprises at least one side port.
15. The catheter of claim 1, wherein said distal tip of said
catheter is tapered.
16. The catheter of claim 1, wherein said distal tip of said
catheter is blunt.
17. The catheter of claim 1, wherein said distal tip of said
catheter has an oblique opening.
18. The catheter of claim 1, further comprising a valve in fluid
communication with the main lumen to control aspiration at the
distal end of said catheter.
19. The catheter of claim 1, further comprising a coating on an
outer surface of said catheter.
20. The catheter of claim 19, wherein said coating is selected from
the group consisting of hydrophilic, hydrophobic, antithrombogenic,
and a combination thereof.
21. The catheter of claim 1, further comprising a therapeutic
device on said distal end.
22. The catheter of claim 21, wherein said therapeutic device is
selected from the group consisting of an angioplasty balloon, a
stent deploying device, and an atherectomy device.
23. An aspiration catheter, comprising an elongate flexible tubular
body having a proximal end and a distal end; a main lumen extending
through the tubular body, said main lumen being sized to receive at
least one separate catheter which is slidably disposed therein; an
aspiration port at the proximal end of the tubular body, the
aspiration port being in fluid communication with the main lumen;
and a tip on the distal end of the tubular body, the tip being
formed of a more flexible material than that used to form the
tubular body.
24. The catheter of claim 23, further comprising a second lumen
adjacent said first lumen adapted to receive a guidewire
therethrough.
25. The catheter of claim 24, wherein said second lumen extends
substantially the entire length of the tubular body.
26. The catheter of claim 24, wherein said second lumen extends
less than 40 cm in a proximal direction from the distal end of the
tubular body.
27. The catheter of claim 24, wherein said second lumen has a slit
through a side wall of the lumen to allow insertion and removal of
the guidewire therethrough.
28. The catheter of claim 23, wherein said distal tip of said
catheter comprises at least one side port.
29. The catheter of claim 23, wherein said distal tip of said
catheter is angled to increase the area of an opening at said
distal tip.
30. The catheter of claim 23, further comprising a valve in fluid
communication with the main lumen.
31. The catheter of claim 23, further comprising a reinforcement
incorporated into at least a portion of said tubular body.
32. An aspiration catheter, comprising: an elongate flexible
tubular body having a proximal end and a distal end; a main
aspiration lumen through said tubular body; an aspiration port on
the proximal end of the tubular body, the aspiration port being in
fluid communication with the main lumen; a therapeutic device
attached to the distal end of the tubular body; and a tip on the
distal end of the tubular body, the tip being formed of a more
flexible material than that used to form the tubular body.
33. The catheter of claim 32, wherein said therapeutic device
comprises an inflatable balloon and said catheter further comprises
a separate inflation lumen adjacent said main lumen.
34. The catheter of claim 32, wherein said therapeutic device is an
atherectomy device.
35. The catheter of claim 32, further comprising a valve in fluid
communication with said main aspiration lumen.
36. The catheter of claim 32, further comprising a reinforcement
incorporated into at least a portion of said tubular body.
37. The catheter of claim 32, wherein said distal tip of said
catheter is tapered.
38. The catheter of claim 32, wherein said distal tip of said
catheter has an oblique opening.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to aspiration catheters for
aspirating emboli, thrombi, and other types of particles from the
vasculature of a patient, the apparatus being particularly well
suited for aspiration within saphenous vein grafts, coronary
arteries, and similar vessels.
[0003] 2. Description of the Related Art
[0004] Human blood vessels often become occluded or completely
blocked by plaque, thrombi, other deposits, emboli or other
substances, which reduce the blood carrying capacity of the vessel.
Should the blockage occur at a critical place in the circulatory
system, serious and permanent injury, or even death, can occur. To
prevent this, some form of medical intervention is usually
performed when significant occlusion is detected.
[0005] Coronary heart disease is an extremely common disorder in
developed countries, and is the leading cause of death in the U.S.
Damage to or malfunction of the heart is caused by narrowing or
blockage of the coronary arteries (atherosclerosis) that supply
blood to the heart. The coronary arteries are first narrowed and
may eventually be completely blocked by plaque, and may further be
complicated by the formation of thrombi (blood clots) on the
roughened surfaces of the plaques. Myocardial infarction can result
from atherosclerosis, especially from an occlusive or near
occlusive thrombi overlying or adjacent to the atherosclerotic
plaque, leading to death of portions of the heart muscle. Thrombi
and emboli also often result from myocardial infarction, and these
clots can block the coronary arteries, or can migrate further
downstream, causing additional complications.
[0006] Various types of intervention techniques have been developed
which facilitate the reduction or removal of the blockage in the
blood vessel, allowing increased blood flow through the vessel. One
technique for treating stenosis or occlusion of a blood vessel is
balloon angioplasty. A balloon catheter is inserted into the
narrowed or blocked area, and the balloon is inflated to expand the
constricted area. In many cases, near normal blood flow is
restored. It can be difficult, however, to treat plaque deposits
and thrombi in the coronary arteries, because the coronary arteries
are small, which makes accessing them with commonly used catheters
difficult.
[0007] Other types of intervention include atherectomy, deployment
of stents, introduction of specific medication by infusion, and
bypass surgery. Each of these methods are not without the risk of
embolism caused by the dislodgement of the blocking material which
then moves downstream. In addition, the size of the blocked vessel
may limit percutaneous access to the vessel.
[0008] In coronary bypass surgery, a more costly and invasive form
of intervention, a section of a vein, usually the saphenous vein
taken from the leg, is used to form a connection between the aorta
and the coronary artery distal to the obstruction. Over time,
however, the saphenous vein graft may itself become diseased,
stenosed, or occluded, similar to the bypassed vessel.
Atherosclerotic plaque in saphenous vein grafts tends to be more
friable and less fibrocalcific than its counterpart in native
coronary arteries.
[0009] Diffusely diseased old saphenous vein grafts with friable
atherosclerotic lesions and thrombi have therefore been associated
with iatrogenic distal embolic debris. Balloon dilatation of
saphenous vein grafts is more likely to produce symptomatic
embolization than dilatation of the coronary arteries, not only
because of the difference in the plaque but also because vein
grafts and their atheromatous plaques are generally larger than the
coronary arteries to which they are anastomosed. Once the plaque
and thrombi are dislodged from the vein, they can move downstream,
completely blocking another portion of the coronary artery and
causing myocardial infarction. In fact, coronary embolization as a
complication of balloon angioplasty of saphenous vein grafts is
higher than that in balloon angioplasty of native coronary
arteries. Therefore, balloon angioplasty of vein grafts is
performed with the realization that involvement by friable
atherosclerosis is likely and that atheroembolization represents a
significant risk.
[0010] Because of these complications and high recurrence rates,
old diffusely diseased saphenous vein grafts have been considered
contraindications for angioplasty and atherectomy, severely
limiting the options for minimally invasive treatment. However,
some diffusely diseased or occluded saphenous vein grafts may be
associated with acute ischemic syndromes, necessitating some form
of intervention.
[0011] There is therefore a need for improved methods of treatment
for occluded vessels such as saphenous vein grafts and the smaller
coronary arteries which decrease the risks to the patient.
SUMMARY OF THE INVENTION
[0012] The present invention provides novel aspiration catheters
for removing plaque, thrombi, emboli, and other types of
obstructions from blood vessels. The present invention
advantageously satisfies the need in the prior art by providing a
catheter adapted to be compactly utilized in even the smaller size
blood vessels. It can also be easily adapted to provide efficient
and speedy evacuation in larger size vessels. This system is
compatible with more common therapy devices in widespread use
today, and is designed for rapid evacuation and ease of use.
[0013] The catheters of the present invention are provided in
either over-the-wire or in single operator form. The catheters are
sized so as to be used in very small blood vessels. Radiopaque
markers are preferably incorporated into the distal ends of the
catheters to facilitate their positioning within the body. The
catheters are provided with varying flexibility along the length of
the shaft, such that they are soft and flexible enough to be
navigated through the vasculature of a patient without causing
damage, but are stiff enough to sustain the axial push required to
position the catheter properly and to sustain the aspiration
pressures.
[0014] The catheters are preferably sized so as to allow the
slidable insertion of a therapy catheter through the main
aspiration lumen of the aspiration catheter. Alternatively, the
therapy catheter can be built over the aspiration catheter. In
either case, the aspiration and therapy catheters can be delivered
simultaneously, saving valuable time during the procedure.
[0015] One embodiment of the aspiration catheter of the present
invention therefore comprises an elongate flexible tubular body
having a proximal end and a distal end. The catheter body or shaft
incorporates a reinforcement such as a metallic braid or coil or a
polymer coil to provide strength and flexibility to the device. A
main lumen extends the length of the tubular body, and an
aspiration port at the proximal end of the catheter body is in
fluid communication with the main lumen, such that aspiration
pressure can be provided through the port and main lumen. The
distal tip on the catheter is formed of a more flexible material
than that used to form the rest of the catheter shaft.
[0016] The reinforcement can be formed from a variety of materials,
including polymers, stainless steel, silver or gold plated
stainless steel, ELGILOY, platinum, nitinol, or a combination
thereof. The distal end of the catheter body is preferably more
flexible than the proximal end, and this can be achieved by
providing a braid or coil density at the distal end which is
greater than the braid or coil density at the proximal end.
[0017] The catheter's main lumen is preferably sized to receive at
least one separate catheter, such as a therapy catheter, which is
slidably disposed therein. The inner diameter of the main lumen is
preferably about 0.045".
[0018] The aspiration catheter of the present invention can include
a second lumen adjacent the main lumen which is adapted to receive
a guidewire therethrough. The second lumen can extend substantially
the entire length of the tubular body, or can extend less than 40
cm or less than 20 cm in a proximal direction from the distal end
of the body. The second lumen can contain a slit through a side
wall to allow insertion and removal of the guidewire therethrough.
In a preferred embodiment, the second lumen has an inner diameter
of approximately 0.020" to receive a 0.014" diameter guidewire.
[0019] The distal tip of the catheter can have at least one side
port to facilitate aspiration. The distal tip can be tapered,
blunt, or angled to create an oblique opening. The catheter
preferably also comprises a valve in fluid communication with the
main lumen, to control the application of aspiration pressure at
the distal end of the device. The aspiration catheter of the
present invention can also incorporate various coatings, such as
hydrophilic or hydrophobic coatings, antithrombogenic coatings, or
a combination thereof.
[0020] In another embodiment of the present invention, the
aspiration catheter comprises an elongate flexible tubular body
having a proximal end and a distal end, a main lumen extending
through the tubular body sized to receive at least one separate
catheter which is slidably disposed therein, an aspiration port at
the proximal end of the tubular body, the aspiration port being in
fluid communication with the main lumen, and a tip on the distal
end of the tubular body, the tip being formed of a more flexible
material than that used to form the tubular body. Again, the
catheter can have a second lumen adjacent the first adapted to
receive a guidewire therethrough, a specially shaped distal tip,
and an optional valve in fluid communication with the main
lumen.
[0021] In yet another embodiment of the present invention, the
aspiration catheter comprises an elongate flexible tubular body
having a proximal end and a distal end, a main aspiration lumen
through the tubular body, an aspiration port on the proximal end of
the tubular body in fluid communication with the main lumen, a
therapeutic device attached to the distal end of the tubular body,
and a tip on the distal end of the tubular body formed of a more
flexible material than that used to form the tubular body itself.
The therapeutic device can be an inflatable balloon and the
catheter can include a separate inflation lumen for the balloon
adjacent the main lumen.
[0022] Accordingly, the catheters of the present invention provide
for very fast and efficient aspiration of the working area
surrounding the occlusion in a blood vessel. The catheters can be
utilized in a wide range of vessel diameters, including extremely
small ones, are easy to use and can quickly and efficiently
evacuate occlusions and debris, allowing the physician to restore
normal blood flow in these vessels in a very short period of
time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a perspective view of a human heart showing a
saphenous vein graft used to bypass a portion of the coronary
arteries.
[0024] FIG. 2 is a side view of an over-the-wire aspiration
catheter in accordance with the present invention.
[0025] FIG. 3 is a cross section of the aspiration catheter of FIG.
2, taken along line 3-3 in FIG. 2.
[0026] FIG. 4 is a cross section of the aspiration catheter of FIG.
2 showing a guide wire over which the aspiration catheter
rides.
[0027] FIG. 5 is a side view of a single operator type aspiration
catheter in accordance with the present invention.
[0028] FIG. 6 is a cross section of the proximal end of the
aspiration catheter of FIG. 5, taken along line 6-6 of FIG. 5.
[0029] FIG. 7A is a cross section of one embodiment of the distal
end of the aspiration catheter of FIG. 5, taken along line 7-7 of
FIG. 5.
[0030] FIG. 7B is a cross section of another embodiment of the
distal end of the aspiration catheter of FIG. 5, also taken along
line 7-7 of FIG. 5, showing a slit in the outer wall of the
guidewire lumen through which the guidewire can be inserted and
removed.
[0031] FIGS. 8A-C are side views of the various embodiments of the
distal end of the aspiration catheter of the present invention.
[0032] FIG. 9 is a perspective view of an over-the-wire aspiration
catheter and guidewire inserted into a saphenous vein graft in
accordance with the present invention, with the vein graft shown
partially cut away.
[0033] FIG. 10 is a schematic view of an occlusion catheter
apparatus for use in the method of the present invention;
[0034] FIG. 11 is a schematic cross-sectional view of a distal
portion of the catheter apparatus shown in FIG. 10.
[0035] FIG. 12 is a perspective view of a valve which can be
positioned at the proximal end of the catheter of the present
invention to control aspiration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0036] The present invention provides novel aspiration catheters
for aspirating emboli, plaque, thrombi or other occlusions from a
blood vessel and methods of using same. The present invention is
adapted for use in the treatment and removal of an occlusion in a
blood vessel in which the occlusion has a length and a width or
thickness which at least partially occludes the vessel's lumen.
Thus, the catheters of the present invention are effective in
treating both partial and complete occlusions of the blood vessels.
As used herein, "occlusion" includes both partial and complete
occlusions, stenosis, emboli, thrombi, plaque and any other
substance which at least partially occludes the vessel's lumen.
[0037] The method of the present invention can be used to provide
aspiration with or without the need for a separate irrigation
catheter and irrigation fluid. In the context of removing plaque,
thrombi or other blockages from blood vessels, it has heretofore
been proposed that an isolated "chamber" surrounding the occlusion
be created prior to attempting treatment, and that separate
irrigation fluid be provided through an irrigation catheter to the
chamber. It has been discovered that isolation of the occlusion is
not required in some cases, and that the occlusion can be
successfully removed through therapy and/or aspirating of the
resulting debris without the need for delivery of a separate
irrigation catheter and irrigation fluid in those vessels where
certain pressure and fluid flow conditions exist, such as saphenous
vein grafts, coronary arteries, carotid arteries and similar
vessels.
[0038] In non-bifurcated areas of the blood vessels, it has been
discovered that fluid from the proximal portion of the same vessel
acts as an infusion source. One can therefore occlude only the
distal portion of the vessel to create a working area surrounding
the occlusion and allow blood to flow from the proximal portion of
the vessel into the working area. The working area surrounding the
occlusion is aspirated through the guiding catheter or aspiration
catheter. It should be noted that, as used herein, "proximal"
refers to the portion of the apparatus closest to the end which
remains outside the patient's body, and "distal" refers to the
portion closest to the end inserted into the patient's body.
[0039] The method and apparatus of the present invention can be
used in any vessel of the body where the pressure is at least 0.2
psi, and preferably, is about 1.2 psi, with a flow rate of at least
10 cc per minute. The method and apparatus are particularly suited
for use in removal of occlusions from saphenous vein grafts,
coronary and carotid arteries, and in other non-branching vessels
having similar pressures and flow where a suitable working area can
be created. A saphenous vein graft is depicted in FIG. 1. The graft
2 is used to bypass one of the occluded coronary arteries 4, and
connects the aorta 6 to the coronary artery at a location distal
the occlusion 8. Although the present invention will be described
in connection with a saphenous vein graft, it should be understood
that this application is merely exemplary, and the method can be
used in other blood vessels as well.
[0040] Apparatus Used With the Present Invention
[0041] 1. Guide Catheter and Occlusion Catheter
[0042] To perform the method of the present invention, a guide
catheter having a single lumen is first introduced into the
patient's vasculature through an incision made in the femoral
artery in the groin and used to guide the insertion of other
catheters and devices to the desired site. Following insertion of
the guide catheter, a second catheter is inserted through the guide
catheter and past the site of the occlusion. The catheter has an
occlusive device, such as an inflatable balloon, filter or other
mechanical occlusive device, attached at its distal end. The
occlusive device should be capable of preventing the migration of
particles and debris from the working area, either through total or
partial occlusion of the vessel. Note that the occlusion of the
vessel need not be complete. Substantial occlusion of the vessel
can be sufficient for purposes of the present invention. The
catheter should be sized so as to be slidable with respect to the
therapy and aspiration catheters inserted over the catheter. The
catheter is preferably made of metal such as stainless steel or
nitinol, plastics, or composites. A guidewire having an occlusive
device on its distal end is also suitable for use in the present
method. The method of the present invention can be effectively
carried out using a number of guidewires or catheters that perform
the function of occluding the vessel and allowing for the slidable
insertion of various other catheters and devices. The term
"catheter" as used herein is therefore intended to include both
guidewires and catheters with these desired characteristics.
[0043] A catheter suitable for use in the present invention is
illustrated in FIGS. 10 and 11. The catheter apparatus 110 is
generally comprised of four communicating members including an
elongated tubular member 114, an inflatable balloon member 116, a
core-wire member 120 and a coil member 122. The catheter apparatus
110 is preferably provided with an outer coating of a lubricous
material, such as Teflon.
[0044] The body member 114 of the catheter apparatus 110 is in the
form of hypotubing and is provided with proximal and distal ends
114A and 114B as well as an inner lumen 115 extending along the
tubular member 114. The balloon member 116 is coaxially mounted on
the distal end 114B of the tubular member 114 by suitable adhesives
119 at a proximal end 116A and a distal end 116B of the balloon
member 116 as in the manner shown in FIG. 11. The core-wire member
120 of the catheter 110 may be comprised of a flexible wire 120.
The flexible wire 120 is joined by soldering, crimping or brazing
at a proximal end 120A of the flexible wire 120 to the distal end
114B of the tubular member 114 as in the manner show in FIG.
11.
[0045] The proximal end 120A of the flexible wire 120 can have a
transverse cross sectional area substantially less than the
smallest transverse cross-sectional area of the inner lumen 115 of
the tubular member 114. The flexible wire 120 can also taper in the
distal end 120B to smaller diameters to provide greater flexibility
to the flexible wire 120. However, the flexible wire may be in the
form of a solid rod, ribbon or a helical coil or wire or
combinations thereof.
[0046] As shown in FIG. 11, the distal end 120B of the flexible
wire 120 is secured to a rounded plug 118 of solder or braze at the
distal end 122B of the coil member 122. The coil member 122 of the
catheter 110 may be comprised of a helical coil 122. The coil
member 122 is coaxially disposed about the flexible wire 120, and
is secured to the flexible wire 120 by soldering or brazing at
about the proximal end 120A of the flexible wire 120 as in the
manner shown in FIG. 11.
[0047] The balloon member 116 is preferably a compliant balloon
formed of a suitable elastic material such as a latex or the like.
The flexible coil 122 is preferably formed of a wire of platinum or
gold based alloys. The flexible core-wire 120 and the tubular
member 114 are preferably formed of a superelastic nickel-titanium
alloy.
[0048] The catheters of the present invention are preferably
provided with a coating on the outer surface, or on both the inner
and outer surfaces. Suitable coatings include hydrophilic,
hydrophobic and antithrombogenic coatings. Examples include heparin
and TEFLON. These coatings can be applied using methods well known
in the art.
[0049] Additional details relative to the catheters described above
are found in copending applications Serial Nos. ______, ______, and
, ______ filed on the same date as the present application,
entitled "Catheter for Emboli Containment" (Attorney Docket No.
PERCUS.009A), "Pre-Stretched Catheter Balloon" (Attorney Docket No.
PERCUS.010A) and "Hollow Medical Wires and Methods of Constructing
Same" (Attorney Docket No. PERCUS.002A), all of which are hereby
incorporated by reference.
[0050] 2. Therapy Catheter
[0051] Once the guiding catheter and second catheter have been
properly positioned inside the vessel, the occlusive device at the
distal end of the catheter is actuated to occlude the vessel distal
to the existing occlusion to create a working area. A therapy
catheter then is delivered to the site of the occlusion. The term
"therapy catheter" is meant to include any of a number of known
devices used to treat an occluded vessel. For example, a catheter
carrying an inflatable balloon for use in balloon angioplasty can
be delivered to dilate the occlusion. Thermal balloon angioplasty
includes the use of heat to "mold" the vessel to the size and shape
of the angioplasty balloon. Similarly, an intravascular stent can
be delivered via a balloon catheter and deployed at the site of the
occlusion to keep the vessel open. Cutting, shaving, scraping or
pulverizing devices can be delivered to excise the occlusion in a
procedure known as atherectomy. A laser or ultrasound device can
also be delivered and used to ablate plaque in the vessel. Various
thrombolytic or other types of drugs can be delivered locally in
high concentrations to the site of the occlusion. It is also
possible to deliver various chemical substances or enzymes via a
catheter to the site of the stenosis to dissolve the obstruction.
The term "therapy catheter" encompasses these and similar
devices.
[0052] 3. Aspiration Catheter
[0053] After the therapy has been performed and the stenosis has
been removed or reduced using any of the methods and apparatus
described above, the working area is aspirated to remove fluid and
debris. Aspiration pressure can be provided through the guide
catheter if desired. A source of negative pressure is attached at
the proximal end of the guide catheter to create reverse flow, and
fluid and debris are aspirated through the guide catheter's main
lumen.
[0054] Alternatively, an aspiration catheter or similar debris
removing device is delivered to the working area to remove
particles and any other debris. The term "aspiration catheter"
includes any device which creates an area of fluid turbulence and
uses negative pressure and reverse flow to aspirate fluid and
debris, and includes those devices which create a venturi effect
within the vessel. It should be noted that any particles which
break free during therapy and aspiration procedures will be kept at
the site of the procedure within the working area by the occlusive
device occluding the distal portion of the vessel in combination
with the blood pressure coming from the proximal portion of the
vessel. The debris is prevented from migrating elsewhere, and
remains localized for removal by aspiration.
[0055] An aspiration catheter particularly suited for use in the
treatment and removal of occlusions in blood vessels is illustrated
in FIG. 2. The catheter 10 includes an adaptor 14, preferably a
female luer adaptor, and a seal 16 at its proximal end. The
catheter 10 further includes an aspiration port 18 to which a
source of negative pressure is attached. The aspiration catheter
further comprises a long tubular body 20 having a distal end 22.
The distal tip 22 can include a radiopaque marker to aid in
locating the tip 22 during insertion into the patient, and is
preferably soft to prevent damage to the patient's vasculature. The
aspiration catheter is preferably about 145 cm in length, although
this length can be varied as desired.
[0056] The aspiration catheter illustrated in FIG. 2 is an
over-the-wire catheter. As seen in FIG. 3, the catheter body 20 is
hollow, with an internal diameter ranging from about 0.030" to
about 0.070". Preferably, the inner diameter is about 0.045".
During insertion of the aspiration catheter 10, the proximal end of
a guidewire 26 is inserted into the distal end of the aspiration
catheter 22, and the aspiration a catheter 10 is slidably advanced
over the guidewire 26, which is positioned inside the hollow lumen
24 of the aspiration catheter 10. The position of the guidewire 26
relative to the body 20 of the aspiration catheter 10 is
illustrated in FIG. 4, but of course can vary. For this type of
aspiration catheter 10, a very long guidewire 26, generally around
300 cm in length, is used to facilitate the insertion of the
aspiration catheter 10 over the guidewire 26.
[0057] Alternatively, the aspiration catheter 30 can be of a single
operator design, as illustrated in FIGS. 5-7. The catheter 30 has
an adaptor 32 and an aspiration port 34 at its proximal end. Like
the over-the-wire aspiration catheter 10, the single operator
aspiration catheter 30 further comprises a long tubular body 36
having a distal end 38. The distal tip 38 can include a radiopaque
marker to aid in locating the tip 38 during insertion into the
patient, and is preferably soft to prevent damage to the patient's
vasculature. At the distal end of the shaft 38, a guidewire lumen
40 is attached. This lumen 40 provides a separate lumen, apart from
the main aspiration lumen 42 of the catheter 30, for the insertion
of the guidewire 26. The inner diameter of the guidewire lumen
ranges from about 0.016" to about 0.020" for use with a 0.014"
guidewire system. In a preferred embodiment, the inner diameter of
the lumen is about 0.019". This guidewire lumen can be less than 10
cm in length, but can extend 30 cm or longer in a proximal
direction. As illustrated in FIG. 7, during delivery of the
aspiration catheter 30, the proximal end of the guidewire 26 is
inserted into the distal end of the guidewire lumen 40, and the
guidewire lumen 40 is slidably advanced over the guidewire 26.
Unlike the over-the-wire catheter 10 described above, only a short
segment of the single operator aspiration catheter 30 rides over
the guidewire 26, and the guidewire 26 remains in the guidewire
lumen 40 and does not enter the aspiration lumen 42 of the
aspiration catheter 30. With the single operator system 30, the
long guidewire 26 used with the over-the-wire catheter 10, and the
extra operator needed to handle it, are not required.
[0058] Although the guidewire lumen 40 is shown in FIG. 5 as being
located only on the distal end 38 of the shaft of the aspiration
catheter 36, the lumen 40 can also be made to extend the entire
length of the shaft 36 if desired. In both embodiments, the
aspiration lumen 42 is advantageously left completely unobstructed
to provide more efficient aspiration. The guidewire lumen 40 can
also include a slit 41 along the entire length in the outside wall
of the lumen as shown in FIG. 7B to facilitate faster and easier
insertion and removal of the guidewire 26 through the side wall of
the lumen. By inserting and removing the guidewire through the side
wall of the aspiration catheter, the need to remove adapters and
attachments from the proximal end prior to slidably advancing or
removing the aspiration catheter over the guidewire is
eliminated.
[0059] In both the over-the-wire and single operator type
aspiration catheters, the elongate catheter shaft must have
sufficient structural integrity, or "stiffness," to permit the
catheter to be pushed through the vasculature to distal arterial
locations without buckling or undesirable bending of the body. It
is also desirable, however, for the body to be fairly flexible near
its distal end, so that the tubular body may be navigated through
tortuous blood vessel networks. Thus, in one preferred embodiment,
the tubular body of the aspiration catheter is formed from a
polymer such as polyethylene or PEBAX (Atochem, France) made to
have variable stiffness along its length, with the proximal portion
of the tubular body being less flexible than the distal portion of
the body. Advantageously, a tubular body of this construction
enables a user to more easily insert the tubular body into vascular
networks difficult to access using conventional catheters of
uniform stiffness. This is because the stiffer proximal portion
provides the requisite structural integrity needed to advance the
catheter without buckling, while the more flexible distal region is
more easily advanced into and through tortuous blood vessel
passageways.
[0060] In one preferred embodiment, variable stiffness along the
length of the catheter shaft is achieved by forming a polymeric
tubular body which incorporates a reinforcement along its length.
For example, the tubular body may be provided with a reinforcing
braid or coil incorporated into its wall structure. The
reinforcement can be formed of metal or of various polymers. To
achieve variable stiffness, the proximal region of the catheter is
provided with a braid or coil having a higher braid or coil density
than that present in the braid or coil of the distal region. The
lower braid density in the proximal region makes it less flexible,
or "stiffer", than the distal region of the catheter.
[0061] The precise density of the braiding or coiling provided to
the proximal, distal and transition regions can be varied
considerably at the time of manufacture, such that catheters having
a variety of different flexibility profiles may be created.
Moreover, the braid or coil density may be varied within the
catheter regions as well, by providing a braid or coil which has a
braid or coil density gradient along its length. For example, the
most proximal part of the proximal region may be provided with a
metallic braid having a braid density of about 10 picks per inch,
with the braid density decreasing at a rate of about 2-10 picks per
inch as the braid extends in the distal direction. This reinforced
construction of the catheter provides adequate proximal stiffness
for axial push, while preventing collapse of the distal tip during
aspiration.
[0062] A variety of different materials, known to be ductile and
shapeable into fine wires, may be used to form the reinforcement.
For example, various polymers, stainless steel, silver or gold
plated stainless steel, platinum, nitinol, or a combination thereof
are suitable. In one preferred embodiment, the braid is formed of
stainless steel, and has a braid density which varies from 10 picks
per inch at the most proximal part of the proximal region of the
catheter, to 100 picks per inch at the most distal part of the
distal region of the catheter.
[0063] Reinforcing braids or coils may be introduced into the
structure of the catheter body through conventional catheter
forming techniques. For example, the tubular body may be formed by
inserting a 72D PEBAX tube into a variable braid density stainless
steel sleeve, and then inserting the sleeved tube into a 72D PEBAX
outer tube of the same length, so that the braided sleeve is
sandwiched between the two tubes. A shaping mandrel may be inserted
within the inner PEBAX tube, and shaping container over the outer
PEBAX tube, and the entire apparatus may then be placed in a hot
box kept at a temperature slightly greater than the melting
temperature of the PEBAX tubes. The PEBAX tubes will melt and fuse
together, and once cooled, will form a tubular body incorporating
the braid. This same technique can be used to form a tubular body
incorporating a coil.
[0064] In another embodiment, variable stiffness of the tubular
body may be achieved by forming the proximal and distal regions of
the tubular body out of polymeric materials having differing
degrees of stiffness. For example, one half of an inner tube of 72D
PEBAX may be inserted into an outer tube of 40D PEBAX, and the
other half of the inner tube may be inserted into a 72D PEBAX outer
tube. The combination may then be heat fused, as described above.
The 40D/72D PEBAX combination forms a more flexible tubular body
than the region of the 72D/72D PEBAX combination. More or less
flexible materials may be used as desired to alter the flexibility
of the resulting tubular body. Furthermore, the flexibility of the
various regions of a tubular body formed in this manner may be
varied further by incorporating a braid or coil having either a
uniform braid density or coil pitch, or a varying density or coil,
into the tubular body, as described above.
[0065] Moreover, any of a variety of different polymeric materials
known by those of skill in the art to be suitable for catheter body
manufacture may be used to form the catheter body. For example, the
body may be formed out of polymers such as polyethylene, PEBAX,
polyimide, polyether etherketone, and the like. Different materials
might also be combined to select for desirable flexibility
properties.
[0066] Also, although the catheter body has been described in the
context of having two regions of differing flexibility, it will be
readily appreciated by those of skill in the art that three or more
regions of differing flexibility may easily be provided, by
adapting the teachings contained herein.
[0067] The distal tip of the aspiration catheter is preferably
formed from 25D to 40D PEBAX with a radiopaque filler such as
BaSO4. Alternatively, the distal end of the catheter can also be
provided with a soft distal tip which is not pre-formed with the
tubular body, but is instead attached to the body as a post
manufacturing step. The distal tip is preferably soft enough and
flexible enough so as to minimize trauma to body vessels as the
catheter is advanced and to facilitate navigation of the catheter
in tortuous vessels, but must also be strong enough to avoid
collapse during aspiration. In one preferred embodiment, the distal
tip is formed as a 0.5 cm sleeve of 25-35D PEBAX and is bonded to
the tubular body by use of an adhesive. Alternately, the distal tip
may be attached to the tubular body by heat bonding, as is known to
those of skill in the art.
[0068] The entire distal end of the aspiration catheter can also be
attached as a separate post manufacturing step. A tubing made of
polyethylene (PE), PEBAX, or polyimide can be fused to the distal
end of the main body section of the catheter. This tubing can be
from about 5 to about 60 cm in length, but is preferably around 30
cm. The distal end of the aspiration catheter can also be provided
with a radiopaque material. Advantageously, radiopaque material
serves as a marker to help the user position the catheter inside
the patient's body. Various well-known radiopaque materials may be
used in the distal end to form the marker, such as platinum or
gold. Alternatively, BaSO4 can be incorporated into the polymer
resin itself.
[0069] FIGS. 8A, 8B, and 8C illustrate various embodiments of the
distal end of the aspiration catheter of the present invention.
FIG. 8A shows the preferred tip 44, wherein the end has been angled
and is oblique to provide effective retrieval of particles. The
angle can be from about 5 degrees to about 90 degrees; an angle of
about 25 degrees is preferred. This angled tip 44 is also shown in
FIG. 5. This angled tip 44 maximizes the area of aspiration. The
distal tip of the aspiration catheter can also be blunt 45, as
shown in FIG. 8B, or can be tapered 46. Side ports 47 can be
drilled along the distal tip of the catheter to enhance the
aspiration rate, as illustrated in FIGS. 8C and 2.
[0070] In another embodiment not shown, the aspiration catheter can
be configured such that the therapy catheter can be inserted
through the lumen of the aspiration catheter. The lumen is made
large enough to accommodate the desired therapy catheter. This
allows the aspiration catheter and the therapy catheter to be
delivered into the patient at the same time. When therapy is
complete, the therapy catheter is removed while the aspiration
catheter remains in place. This eliminates the need to separately
deliver the aspiration catheter after removal of the therapy
catheter, saving valuable time. It is preferable that the size of
the guide catheter used during this type of procedure be sized from
at least 8 to about 10 French to accommodate the size of the
"over-the-therapy-catheter" aspiration catheter, In yet another
embodiment, also not shown, the therapy catheter can be built over
the aspiration catheter. For example, a dual or triple lumen
catheter having a dilatation balloon at its distal end can be used.
One lumen is used to inflate the dilatation balloon to be used for
angioplasty, while the second lumen is used for aspiration. The
third lumen is used as a guidewire lumen. Alternatively, the
aspiration catheter can be designed to deploy a stent within the
occluded artery, or could include an atherectomy device on its
distal end. These designs allows a single combined aspiration
catheter and therapy catheter to be delivered into the patient.
When therapy is complete, aspiration is carried out without the
need to first remove the therapy catheter or separately deliver an
aspiration catheter.
[0071] The proximal end of the aspiration catheter can be fitted
with a valve, as illustrated in FIG. 12. The valve allows the user
to regulate the aspiration pressure. For example, a syringe can be
connected to the valve and aspiration port at the proximal end of
the catheter. With the valve closed, the syringe piston can be
retracted completely to provide a vacuum. The valve is then opened
to provide aspiration at the distal end of the aspiration catheter.
Aspiration pressure can be provided in short bursts or continuously
as the user desires by opening and closing the valve at the
proximal end of the catheter. This valve therefore provides control
over the aspiration within the vessel. The aspiration catheters of
the present invention can also include a coating on the outer
surface. Suitable coatings include hydrophilic, hydrophobic, and
antithrombogenic coatings, or a combination thereof. Examples of
suitable coatings include heparin and TEFLON.
[0072] Use of the devices just described will now be explained in
connection with the method of the present invention.
[0073] Method of the Present Invention
[0074] The method of the present invention as used to remove plaque
and any associated thrombi from a saphenous vein graft is described
below in connection with FIG. 9. Again, it should be noted that
this application is merely exemplary, and that the method of the
present invention can be used in other blood vessels and to remove
other types of occlusions as well.
[0075] A guide catheter (not shown) is introduced into the
patient's vasculature through an incision in the femoral artery in
the groin of the patient. The guide catheter has a single large
lumen, and is used to guide the insertion of other catheters and
devices. The guide catheter is advanced until it reaches the aorta
and the ostium of the vein graft, where it will remain in place
throughout the procedure. Fluoroscopy is typically used to guide
the guide catheter and other devices to the desired location within
the patient. The devices are frequently marked with radiopaque
markers to facilitate visualization of the insertion and
positioning of the devices within the patient's vasculature.
[0076] Next, a catheter or guidewire 50 having an occlusive device
at its distal end is delivered through the guide catheter into the
saphenous vein graft 5 and past the site of the occlusion 56. In
this example, the occlusive device is an inflatable balloon 52. The
balloon 52 is inflated to occlude the vein graft 5 at a site distal
to the occlusion 56. The blood coming from the aorta enters the
saphenous vein graft 5 and keeps any particles 58 dislodged during
the procedure from flowing proximally. In addition, the blood
pressure and flow coming from the aorta provides the irrigation
necessary for aspiration. As noted above, the blood pressure in the
vessel is preferably at least about 0.2 psi, and the proximal flow
rate is at least about 10 cc per minute.
[0077] Once the vein 5 is occluded, a therapy catheter (not shown)
is delivered, if desired. The therapy catheter can be any of a
number of devices, including a balloon catheter used to perform
angioplasty, a catheter which delivers a stent, a catheter for
delivering enzymes, chemicals, or drugs to dissolve and treat the
occlusion, an atherectomy device, a rheolitic device, or a laser or
ultrasound device used to ablate the occlusion. Alternatively, the
therapy catheter can be eliminated and use of the guide catheter or
a separate aspiration catheter alone can be used to aspirate the
occlusion. This method is especially useful to remove emboli from
the coronary arteries following acute myocardial infarction,
because the aspiration catheter can be made small enough to enter
the coronary arteries.
[0078] Once the desired therapy is performed, the therapy catheter
is withdrawn from the patient's body and an aspiration catheter 60
is delivered over the guidewire 50 and through the guiding
catheter. The aspiration catheter 60 rides over the guidewire 50
with the guidewire 50 inserted through the aspiration lumen 62 of
the catheter 60. Alternatively, a single operator type aspiration
catheter can be used, in which only a portion of the aspiration
catheter rides over the guidewire, which is inserted into a
separate guidewire lumen. FIG. 9 illustrates the treatment site
after the over-the-wire aspiration catheter 60 is inserted into the
saphenous vein graft 5.
[0079] The distal tip of the aspiration catheter 64 is initially
positioned close to the occlusive balloon 52. The operator then
slides the aspiration catheter in a proximal direction, increasing
the distance between the distal tip 64 and the balloon 52.
Aspiration can therefore occur anywhere between about 0 to 20 cm
proximal to the occlusive device. If desired, the distal tip of the
aspiration catheter 64 can be slidably advanced in the distal
direction more than once to ensure complete aspiration of all
debris. The blood pressure supplied by the aorta will move any
particles 58 from a position proximal to the distal tip of the
aspiration catheter 64, thus allowing them to be aspirated, as
illustrated by the arrows in FIG. 9. If a particle, however, is too
far distal to the tip of the aspiration catheter 64, the blood
pressure will keep it there and not allow it to aspirated from the
vessel 5. Once aspiration has begun, additional blood will flow
into the area, creating turbulence and allowing for successful
removal of debris.
[0080] A preferred source of negative pressure is any container
containing a fixed vacuum, such as a syringe, attached to the
proximal end of the aspiration catheter at the aspiration port 34
(see FIG. 5). A mechanical pump or bulb or any other appropriate
source of negative pressure can also be used. Other aspiration
methods, including those which utilize a venturi effect, can also
be used. The difference between the existing pressure within the
vessel and the aspiration pressure within the vessel should not
exceed 60 psi, and more preferably, should not exceed about 30 psi.
If too much aspiration pressure is applied, the change in pressure
in the vessel will be too great and damage may occur to the vessel
itself.
[0081] After the area inside the graft 5 just proximal to the
occlusive balloon 52 is aspirated to remove any particles 58 or
other debris, the aspiration catheter 60 is removed. The balloon 52
is deflated and the guidewire 50 and guiding catheter are
removed.
[0082] As described above, the aspiration catheter can be sized
such that it can receive the therapy catheter within its lumen, or
the therapy catheter can be built over the aspiration catheter. For
example, an angioplasty balloon can be attached to the distal end
of the aspiration catheter. Alternatively, the aspiration catheter
can be designed to deploy a stent within the occluded artery, or
could include an atherectomy device on its distal end. The
aspiration catheter and the therapy catheter are delivered over the
guidewire and into the vein graft together. When therapy is
complete, the therapy catheter is removed while the aspiration
catheter remains in place. When aspiration is complete, the
aspiration catheter, guidewire and guiding catheter are removed
from the patient's body. Delivering the aspiration catheter and
therapy catheter together saves time, which is critical during
these types of procedures. Alternatively, the guide catheter can be
used to provide aspiration through its main lumen.
[0083] While the foregoing detailed description has described
several embodiments of the apparatus and methods of the present
invention, it is to be understood that the above description is
illustrative only and not limiting of the disclosed invention. It
will be appreciated that the specific dimensions of the various
catheters and guidewires can differ from those described above, and
that the methods described can be used within any biological
conduit within the body and remain within the scope of the present
invention. Thus, the invention is to be limited only by the claims
which follow.
* * * * *