U.S. patent application number 13/664499 was filed with the patent office on 2013-11-07 for debulking catheter.
This patent application is currently assigned to Covidien LP. The applicant listed for this patent is Covidien LP. Invention is credited to William John Olson.
Application Number | 20130296901 13/664499 |
Document ID | / |
Family ID | 39170735 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130296901 |
Kind Code |
A1 |
Olson; William John |
November 7, 2013 |
DEBULKING CATHETER
Abstract
A catheter includes a rotatable cutter in a catheter body
adjacent a window and operatively connected to a rotatable shaft
for rotation therewith. The rotatable cutter includes a
proximally-facing cutting edge. The rotatable cutter is selectively
positionable to a cutting position in which the rotatable cutter
extends partially outside the window to expose the cutting edge
such that the catheter can be moved proximally within the body
lumen as the rotatable cutter is rotating to remove tissue from the
lumen and direct the removed tissue through the window and into a
removed-tissue lumen.
Inventors: |
Olson; William John; (Menlo
Park, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covidien LP; |
|
|
US |
|
|
Assignee: |
Covidien LP
Mansfield
MA
|
Family ID: |
39170735 |
Appl. No.: |
13/664499 |
Filed: |
October 31, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11934670 |
Nov 2, 2007 |
8328829 |
|
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13664499 |
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Current U.S.
Class: |
606/159 |
Current CPC
Class: |
A61B 17/32075 20130101;
A61B 2017/320775 20130101; A61B 2017/320791 20130101; A61B
17/320783 20130101 |
Class at
Publication: |
606/159 |
International
Class: |
A61B 17/3207 20060101
A61B017/3207 |
Claims
1. A catheter for removing tissue from a body lumen of a subject,
the catheter comprising: an elongate catheter body having proximal
and distal ends and a longitudinal axis extending therebetween, the
catheter body being sized and shaped for introduction into the body
lumen of the subject; a window adjacent the distal end of the
catheter body and extending generally transversely into the
catheter body relative to the longitudinal axis of the catheter
body for receiving removed tissue from the body lumen; a
removed-tissue lumen in the catheter body and in communication with
the window for receiving removed tissue passing through the window;
a rotatable shaft having proximal and distal ends and a
longitudinal axis extending therebetween, the shaft extending
longitudinally within the catheter body and configured for
selective rotation about its longitudinal axis relative to the
catheter body; a rotatable cutter in the catheter body adjacent the
window and operatively connected to the rotatable shaft for
rotation therewith, the rotatable cutter including a
proximally-facing cutting edge, wherein the rotatable cutter is
selectively positionable to a cutting position in which the
rotatable cutter extends partially outside the window to expose the
cutting edge such that the catheter can be moved proximally within
the body lumen as the rotatable cutter is rotating to remove tissue
from the lumen and direct the removed tissue through the window and
into the removed-tissue lumen.
2. The catheter set forth in claim 1, wherein the rotatable cutter
is selectively lockable in the cutting position.
3. The catheter set forth in claim 2, wherein the cutting edge
extends about 0.025 mm to 0.64 mm outside the window when the
rotatable cutter is in the cutting position.
4. The catheter set forth in claim 1, wherein the catheter includes
a transport mechanism for moving the removed tissue proximally
within the removed-tissue lumen.
5. The catheter set forth in claim 4, wherein the rotatable shaft
extends into the removed-tissue lumen, and the transport mechanism
comprises a helical screw on the rotatable shaft.
6. The catheter set forth in claim 1, wherein the rotatable shaft
is selectively moveable longitudinally relative to the catheter
body to impart selective longitudinal movement of the rotatable
cutter relative to the window.
7. The catheter set forth in claim 1, further comprising a
stationary cutting element for removing tissue from the lumen, the
stationary cutting element located adjacent to the window.
8. The catheter set forth in claim 7, wherein the rotatable shaft
is selectively moveable longitudinally relative to the catheter
body to impart selective longitudinal movement of the rotatable
cutter relative to the stationary cutting element between a first
longitudinal position, in which the rotatable cutter is in
registration with the window and the cutting edge of the rotatable
cutter is spaced a first longitudinal distance from the stationary
cutting element to define a first effective open area of the window
leading to the removed-tissue lumen, and a second longitudinal
position, in which the rotatable cutter is in registration with the
window and the cutting edge of the rotatable cutter is spaced a
second longitudinal distance from the stationary cutting element to
define a second effective open area of the window leading to the
removed-tissue lumen, wherein the first longitudinal distal is
greater than the second longitudinal distance and the first
effective open area of the window is greater than the second
effective open area of the window.
9. The catheter set forth in claim 1, wherein the rotatable cutter
is selectively positionable to a non-cutting position in which an
entirety of the rotatable cutter is disposed within the catheter
body and the cutting edge is not exposed through the window.
10. A catheter for removing tissue from a body lumen of a subject,
the catheter comprising: an elongate catheter body having proximal
and distal ends and a longitudinal axis extending therebetween, the
catheter body being sized and shaped for introduction into the body
lumen of the subject; a window adjacent the distal end of the
catheter body and extending generally transversely into the
catheter body relative to the longitudinal axis of the catheter
body for receiving removed tissue from the body lumen; a
removed-tissue lumen in the catheter body and in communication with
the window for receiving removed tissue passing through the window;
a stationary cutting element for removing tissue from the body
lumen, the stationary cutting element located adjacent to the
window and configured to direct tissue cut from the body lumen
toward the window; a plunger assembly in the elongate catheter
body, the plunger assembly including a shaft having proximal and
distal ends and a longitudinal axis extending therebetween, the
shaft extending longitudinally through the elongate catheter body
and configured for rotation about its longitudinal axis and
longitudinal movement relative to the catheter body; a plunger
secured adjacent the distal end of the shaft within the
removed-tissue lumen, the plunger configured to rotate with the
shaft and move longitudinally with the shaft within the
removed-tissue lumen, wherein the plunger is longitudinally
moveable within the removed-tissue lumen between a first
longitudinal position, in which the plunger is in registration with
the window and spaced a first longitudinal distance from the
stationary cutting element to define a first effective open area of
the window leading to the removed-tissue lumen, and a second
longitudinal position, in which the plunger is in registration with
the window and spaced a second longitudinal distance from the
stationary cutting element to define a second effective open area
of the window leading to the removed-tissue lumen, wherein the
first longitudinal distal is greater than the second longitudinal
distance and the first effective open area of the window is greater
than the second effective open area of the window.
11. The catheter set forth in claim 10, wherein the window is at
least partially defined by a proximal window edge and a distal
window edge of the catheter body, wherein the stationary cutting
element is adjacent said proximal window edge.
12. The catheter set forth in claim 11, wherein the stationary
cutting element extends along said proximal window edge.
13. The catheter set forth in claim 12, wherein the stationary
cutting element is V-shaped.
14. The catheter set forth in claim 11, wherein the stationary
cutting element faces distally.
15. The catheter set forth in claim 14, wherein the first
longitudinal position of the plunger is distal to the second
longitudinal position of the plunger.
16. The catheter set forth in claim 10, wherein the plunger
includes a cutting element.
17. The catheter set forth in claim 16, wherein plunger comprises a
cutting wheel facing proximally.
18. The catheter set forth in claim 17, wherein the shaft of the
plunger assembly includes a helical screw for transporting removed
plaque proximally within the removed-tissue lumen.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent Ser. No. 11/934,670, filed Nov. 2, 2007, the entirety of
which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] Restriction of blood circulation due to the atherosclerotic
build up of plaque in arteries is the source of much mortality and
morbidity. Plaque deposits in cardiac arteries can result in angina
and myocardial infarction. Plaque deposits in peripheral arteries
of the limbs can result in peripheral artery disease (PAD). PAD
affects about 20% of the population over 70, and in more severe
forms (which afflict about 2 million people in the U.S.) can lead
to non-healing ulcers, infection, and eventually loss of limb due
to amputation. Most people die within two years of such
amputations.
[0003] Although many techniques, such as stenting and balloon
angioplasty, have been developed to help restore circulation to
plaque occluded cardiac arteries, these methods tend to be less
effective for peripheral arteries. Stents, although well suited to
low-mobility cardiac arteries, tend to either restenose or
frequently break in peripheral limb arteries because these arteries
are subjected to greater movement and mechanical stress. Balloon
angioplasty, which stretches the artery walls while it compresses
and redistributes plaque, tends to cause a greater and typically
less acceptable amount of artery wall damage when it is used with
peripheral arteries. Additionally, since angioplasty simply
redistributes plaque rather than actually removing plaque, in the
higher mobility peripheral arteries, the redistributed plaque tends
to relatively quickly distribute itself back into an unacceptable
configuration again.
[0004] From the surgical perspective, one of the most ideal ways to
treat arteries blocked by plaque is to remove the plaque from the
inside of the artery using an atherectomy catheter. Such catheters,
which come in a variety of different designs, can be introduced
into the body at a convenient location and threaded inside the
artery to the plaque occluded target region (which can usually be
determined exactly using fluoroscopy and appropriate radio opaque
contrast dyes). Once they are at the correct region, atherectomy
catheters then surgically remove the occluding plaque.
[0005] Many different types of atherectomy catheter devices have
been proposed, including catheters with rotating burrs (Boston
Scientific Rotablator), lasers to photo-dissolve tissue
(Spectrametics Laser Catheter), and cutter-balloon catheters
(Guidant AtheroCath). All have certain drawbacks, however, such as
difficulty in traversing through small and torturous arteries to
get to the plaque occluded target zone or zones.
[0006] One of the biggest problems plaguing prior art atherectomy
catheters is the problem of gracefully handing the shaved plaque
remnants. Some designs, such as the Rotablator, make no attempt at
all to handle the liberated plaque fragments, and instead let the
fragments migrate through the circulation. This can cause many
problems, because the liberated plaque remnants can be
thrombogenic, and can end up causing downstream occlusions. Other
catheter designs attempt to reduce this problem by capturing the
plaque shavings and safely removing them from the body. Capturing
the plaque shavings also makes the samples available for pathologic
and medical diagnostic examination, and may give important
information as to the root causes behind the plaque build-up in the
first place.
[0007] Examples of such cutting catheters include Andreas U.S. Pat.
No. 5,250,059; Farley, U.S. Pat. No. 5,624,457; Conley U.S. Pat.
No. 5,669,920; Schultz U.S. Pat. No. 5,836,957; and Rogers U.S.
Pat. No. 6,120,515. Other prior art includes Snow, U.S. application
Ser. No. 09/930,372; Methods for removing atheromatous material
from a body lumen
[0008] More recent atherectomy catheters, such as the Fox Hollow
SilverHawk articulated rotating blade atherectomy catheter, have
been designed to address such issues. The SilverHawk catheter
(exemplified by U.S. patent application Ser. Nos. 10/027,418;
10/288,559; 10/896,747; and others) uses a unique rotating blade,
window, and hinged hollow nose design, which can be controlled to
either assume a straight position or an angled (drooped)
position.
[0009] To use the SilverHawk atherectomy catheter, the operator
will usually first insert a guide wire to the proper location,
attach the SilverHawk to the guidewire, and introduce the
SilverHawk through a convenient artery port, often located near the
groin region. The operator then maneuvers the SilverHawk device to
the appropriate region of plaque with the SilverHawk hinged
(bendable) nose in a straight configuration. Once at the target
zone, the operator then bends the angle of the SilverHawk's hollow
nose. The nose contacts the artery wall opposite the plaque target,
and which in turn results in an opposing force that presses the
catheter's window and cutter against the plaque.
[0010] The operator will then spin-up the cutter, and move the
catheter across the target zone. The rotary cutter cuts a thin
strip of plaque, which is directed, by the motion of the cutter and
the device's geometry, into the hollow nose cone. The cuttings stay
in the nose cone, where they can eventually be removed from the
body and analyzed.
[0011] The SilverHawk atherectomy catheter represented a
significant advance in the state of the art, because it enabled
substantially longer regions (often several centimeters or more) of
plaque to be shaved for each pass of the catheter over a region. An
additional advantage was that the catheter could be rotated;
exposing the window and the rotating blade to another region, and a
target region of plaque could thus be shaved multiple times,
allowing precise control over the amount and geometry of the plaque
reduction process.
[0012] Although the SilverHawk catheter demonstrated the utility of
this type of approach, further improvements were still desirable.
In particular, the available plaque storage space in the device's
hollow nose cone was limited, and improvements in trimming
partially attached plaque shavings were also desirable.
[0013] One problem was that whenever the nose cone filled with
plaque, the catheter needed to be pulled from the body, cleaned,
and then laboriously rethreaded to the correct location in the
target zone again. This tended to significantly prolong the length
and effort required for many medical procedures, and thus was
undesirable to both physician and patient alike. Methods to reduce
this burden were thus highly desirable.
[0014] A second problem was how to optimize plaque handling near
the edges of trimmed areas. In some cases, plaque would be
partially severed by the rotating cutter, yet still remain
partially attached to the artery wall. This dangling plaque
sometimes had a tendency to deform when a cutter passed over it,
rather than be neatly severed and stored in the catheter's plaque
storage compartment. Here, an alternative cutting means that could
either cut the plaque from the opposite direction, and/or pinch
off, cut, and store dangling plaque would be advantageous.
[0015] Atherectomy design engineers face some formidable design
challenges, however. In order to navigate the narrow and torturous
arteries, veins and other lumens of the body, such catheters must
have extremely small diameters, usually on the order of 1 to 3
millimeters (3-9 French). At the same time, the devices must be
flexible enough to be threaded through such arteries, yet have
sections that are rigid enough to accomplish the required
positioning, cutting, and plaque storage functions.
[0016] Due to these many design constraints, mechanical designs
that might be relatively simple to execute with larger diameter
devices become very problematic at such extremely small diameters.
Additional constraints, such as the need to use biocompatible
materials, the need for extremely high reliability, and the need
for accommodate a wide variety of different plaque targets in
different patients make the design of such devices quite
challenging.
BRIEF SUMMARY OF THE INVENTION
[0017] The present invention is an improved atherectomy catheter
designed with increased plaque carrying cap ability, and an
improved ability to trim plaque, including the dangling portions of
plaque that are still partially attached to artery or other body
lumen walls. The catheter will normally comprise a long catheter
tube, with a cutting head attached to the tube comprising at least
a hollow rigid tubular portion with a bladed edge window, and an
adjustable angle distal nose portion. The catheter head may
additionally contain either a moveable plunger or a moveable
plunger cutting wheel. The catheter may achieve its plaque cutting
action by more than one modality.
[0018] In a first cutting modality, an operator controlled variable
angle (drooping) nose or nose region is bent by the operator. The
tip of the nose contacts an opposite artery wall or other body
lumen, forcing (as an equal and opposite reaction) a bladed window
opening on the opposite side of the catheter up against a target
region of plaque on the opposite artery wall. The operator then
retracts a plunger or shield that obscures the bladed edge of the
catheter window, and advances the catheter. The bladed window edge
shaves the plaque, and plaque shavings pass through the window
opening into a hollow storage space inside the catheter, where the
shavings are stored. The shavings may then be subsequently removed
from the body and subjected to pathological or medical diagnostic
analysis as needed.
[0019] In a second cutting modality, an operator uses the
catheter's moveable plunger to close the catheter's open window. As
it closes the window, the plunger presses any dangling plaque that
is protruding into the window up against the bladed edge of the
window. The dangling plaque is severed by the pinching action of
the window blade and the plunger, and again enters the hollow
storage space inside the catheter.
[0020] In a third cutting modality, an operator spins up a moveable
combination plunger and cutting wheel, and uses the spinning
plunger/cutting wheel to almost close the catheter's open window,
while optionally advancing or retracting the catheter. The dangling
plaque is thus subjected to cutting action from both sides, as well
as a pinching action, and an optional force due to advancement or
retraction of the catheter. The severed plaque fragment and again
enters the hollow storage space inside the catheter.
[0021] In a fourth cutting modality, an operator may spin up a
moveable plunger cutting wheel, and cut plaque by alternately
advancing and retracting the catheter head. Plaque will be
subjected to cutting from the bladed window when the catheter is
advanced, and will be subjected to cutting from the rotating
plunger when the catheter is retracted. As before, the shavings
will again enter into the hollow storage space inside the
catheter.
[0022] Normally, when the operator wishes to advance or retract the
catheter through the body either towards or away from the target
zone, the operator will use a mechanism connected to the plunger to
close the window. This helps insure that the bladed window edge
will not inadvertently damage non-target regions of the arteries or
other body lumens.
[0023] It is contemplated that in normal operation, the operator
may switch between various cutting modalities as appears best for
the given situation. The present design gives the operator a
greater number of cutting options than prior art designs, thus
allowing quicker and more precise procedures to be accomplished.
Due to the fact that the present invention stores the plaque
shavings in the relatively large hollow storage space of the
catheter body, rather than the relatively small storage space of
the catheter nose (as was done with prior art designs), the
catheter may additionally operate for a longer period of time
before it must be withdrawn from the body for cleaning, and
reinserted. This speeds up the procedure time, and reduces the
burden on patients and physicians.
[0024] In an alternative embodiment of the present invention,
sensors may also be added to the design to help the operator
properly position the device relative to target plaque or other
body lumen targets of interest, and also properly orient the
cutting window of the device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows an overall view of the unit, including the
proximal operator control, the catheter, and the distal catheter
cutting head.
[0026] FIG. 2A shows a top view of the distal catheter cutting
head.
[0027] FIG. 2B shows a side view of the distal catheter cutting
head with the adjustable angle catheter nose in the up
configuration.
[0028] FIG. 2C shows a side view of the distal catheter cutting
head with the nose angled down in a drooped configuration.
[0029] FIG. 3 shows how a guide wire may be threaded through the
catheter and the distal cutting head.
[0030] FIG. 4A shows the razor edge on the catheter window cutting
through plaque with the plug in an open window configuration.
[0031] FIG. 4B shows the how dangling plaque may be cut off and
stored in the head of the device by closing the plug.
[0032] FIG. 5 shows a variety of different catheter window blade
edges.
DESCRIPTION OF THE INVENTION
[0033] The present art is normally intended for use with human
patients, as well as various veterinary applications. For
simplicity, this combined human or animal use will be referred to
as use in mammals, although of course such devices could also be
used in appropriate non-mammal animals such as birds, reptiles, and
amphibians, etc., as appropriate.
[0034] It should also be understood that although the examples of
cutting unwanted plaque deposits in arteries are used throughout
this disclosure, the actual invention may be used for a broader
variety of applications, including removing tumors, getting
biopsies, etc. in arteries, veins, and any other tubular or roughly
tubular body lumen.
[0035] Nomenclature: The handle end of the catheter is the proximal
location, and the nose cone tip of the catheter is the distal
location.
[0036] An overview of the device is shown in FIG. 1. The device
consists of a handle (101), one or more control knobs, tabs, or
switches (102), a long catheter tube or shaft (103), and the
cutting atherectomy head (104).
[0037] The catheter tube or shaft (103) will typically consist of a
flexible tube, which is often hollow and capable of passing a guide
wire, as well as optionally other materials such as drugs and
contrast materials, control wires, drive shafts, sensors, sensor
fibers or wires, ultrasonic signals, and the like. The control
wires may optionally be used to operate plunger settings, nose
angle, and the like as will be discussed in the next sections.
[0038] In some embodiments, the handle (101) may also contain a
battery and motor for driving a screw material transport device in
the catheter head (104), or a rotating combination plunger and
cutter. In this case, the tube (103) may contain a shaft or hollow
shaft additionally capable of transmitting torque from a motor
mounted in the handle to the atherectomy head.
[0039] The cutting atherectomy head (104) will typically consist of
a hollow body and a moveable tapered nose, which in some
embodiments is connected to the front of the hollow body by at
least one hinge. The head will additionally consist of at least a
window with a razor edge, and a moveable plunger or combination
plunger/cutter that can transition from a more distal (open window)
position to a more proximal (closed window) position. Head (104)
may additionally contain openings or ports to accommodate a
guidewire to allow the catheter head to be precisely threaded
through torturous arteries, veins, or other body lumens.
[0040] In the event that use with a guide wire is desired, to allow
the head's bladed window and plunger cutting mechanism to operate
freely and without risk accidentally cutting or entangling with the
guide wire, the guide wire may be routed to exit from the proximal
region of the catheter head, and then reenter the catheter head at
the distal region of the head, thus skipping the plaque cutting and
storage regions of the head. In some configurations, the guide wire
will reenter the catheter head at the distal nose region, travel
through the nose end of the head for a short distance, and then
finally exit the head again through a third exit port, often
located near the tip of the catheter's nose located at the extreme
distal end of the catheter.
[0041] FIGS. 2A, 2B, and 2C show close-ups of the cutting
atherectomy head (104) from various angles. FIG. 2A shows the head
from the top. The figure shows the head's adjustable angle nose
cone (201), hinge pins (202), moveable plug (203), window opening
(204), window blade edge (205), the plug movement shaft (206) an
optional helical screw to help move and compact any plaque shavings
(207), and the main body of the head (210).
[0042] The catheter's nose (201) usually has a tapered or conical
atraumatic design intended to allow the catheter head to easily
migrate through arteries. It may be composed of softer materials,
and may additionally have an internal coiled spring or other means
to allow the tip to bend somewhat as needed to migrate through
torturous arteries and other body lumen structures.
[0043] FIG. 2B shows the same head from the side. Here the
adjustable angle nose (201) is shown in the "up" or straight
configuration, which allows the catheter head to migrate though the
torturous arteries and body lumens with maximum ease. In this
figure the plug (203) is shown in the extended configuration and
the window (204) is open. In actual operation however, when the
head is being moved through the arteries to a target site, plug
(203) will normally be in a closed position, closing window (204),
and normally blocking window blade (205). This closed position
helps to prevent the window blade (205) from accidentally nicking
or cutting non-target regions of the arteries or other body lumens
while the device is being moved to and from its various target
zones.
[0044] FIG. 2C shows the head from the side, showing the catheter
operating in a cutting configuration after the catheter head has
been threaded to its designated target zone. Once the catheter is
in position, the adjustable angle catheter nose (201) is put into a
bent or drooped position through either a cam mechanism (not
shown), or other means. Suitable cam mechanisms and deflection
means for adjusting the angle of similar type catheter noses were
previously taught by copending application Ser. Nos. 10/896,741,
and 10/027,418, the contents of which are incorporated herein by
reference.
[0045] In this angled or drooped position, the nose cone (201),
which is shown held to the main body (210) by hinge pins (202),
rotates to a "bent" configuration. This adjustable angle nose is
typically rotated by the operator increasing the angle of the bend
until the nose tip makes contact with the opposite wall of a body
lumen (i.e. an opposite artery wall). Once the nose tip makes
contact with an opposite wall, an equal and opposite force is
generated (by the normal laws of physics) that acts to push or
"urge" window (204) and the blade (205) against the target zone on
the opposite lumen wall. This target is usually a plaque occluded
region of an artery wall.
[0046] This design thus differs from earlier cutting catheter
designs, such as the Guidant AtheroCath, which used a balloon on
one side of the cutting head to force the cutting portion of the
catheter against the target plaque.
[0047] One problem with earlier cutting catheter designs is the
catheters either did not collect the plaque shavings at all
(potentially causing significant complications and adverse
effects), or else the earlier designs had only a relatively limited
ability (storage volume) to store this collected plaque.
[0048] As an example, prior art atherectomy catheters typically
stored plaque shavings in the hollow distal (nose) side of the
catheter head. Although functional, the volume of this hollow nose
is quite limited. As an unfortunate consequence, medical procedures
had to be frequently interrupted whenever the catheter head filled
up with plaque. The catheter then had to be carefully withdrawn,
stored plaque removed, then slowly and carefully reinserted back to
the target zone. This prolonged the medical procedures, and led to
strain on the patient and physician, as well as encouraging less
complete plaque removal.
[0049] By contrast, the present art solves this limited storage
problem by adapting a novel design in which the plaque cutting
blade (205) is mounted on one or more edges of a hollow window
(204) that in turn opens up into a much larger plaque shaving
storage area (206) contained in the main body of the catheter head
(210).
[0050] A second advantage of the present invention's bladed window
design that it gives the operator a wider variety of cutting
options. The operator may use the bladed window (204, 205) as a
scraper, paring off unwanted plaque by advancing the catheter. The
operator may use the bladed window, in combination with a plunger
(203) to pinch off plaque. The operator may use the bladed window
with a combination plunger and rotary cutter to cut plaque from
both directions. The net effect is that the operator has a greater
variety of cutting means at his or her disposal, and can thus
choose the most appropriate means to fit the particular target at
hand.
[0051] In some embodiments, the catheter may additionally have
sensors, such as directional ultrasonic or infrared sensors,
mounted on the catheter head. In one embodiment, the orientation of
the sensor or sensors is directed to give the operator information
as to the status of the plaque and/or artery of or other body lumen
that is facing the cutting window of the catheter. This can allow
the operator to determine if the catheter is in the proper
orientation relative to its intended target. Examples of such
sensors were described in more detail in application Ser. No.
10/421,980, the contents of which are incorporated herein by
reference.
[0052] Device dimensions: Typically the catheter cutting head (210)
will have a diameter between about 1 to 2.2 millimeters. The
cutting window (204) will typically have a length of about 1.2 to
2.5 millimeters. In embodiments where the plunger (203) is a
plunger equipped with a cutting wheel that contains a cam or other
orientation control mechanism that allows the cutting wheel portion
of the plunger to extend slightly outside the window, the plunger
orientation control mechanism may allow the plunger to at least
temporarily be locked into a position that allows the cutting outer
edge of the plunger to extend about 0.025 to 0.64 mm outside the
cutting window.
[0053] This adjustable "slightly outside" configuration can also be
used when the plunger does not have a cutting edge as well, as a
slightly protruding plunger creates a "safety razor" type
configuration in which any tendency of the blade to cut too deeply
is mitigated by the force of the artery wall against the protruding
plunger.
[0054] The net effect of the present design is to allow the
operator to move the catheter backward along the target region of
plaque, and shave off a long thin portion of this plaque using the
cutting edge of plunger (203). The operator may then move the
catheter forward, and cut off plaque using blade (205). In this
configuration, both forward and backward movement can produce
cutting activity, if desired.
[0055] The plunger (203) will typically have a diameter of about
1.14 mm, and a width typically at least as long as window (204).
The window facing side of the plunger and may have a dull edge, a
sharp cutting edge, other edge. The geometry of the plunger's
window-facing edge may be chosen so that when the plunger is moved
to close the window, window blade (205) may be partially or totally
covered or obscured by the plunger. Alternatively, the plunger may
be designed to provide a flat or curved edge to help pinch
material, and may be designed as to stop just short of contacting
the window blade so as to avoid dulling window blade (205). If
plunger (203) is designed to function as a cutting wheel, then
usually some sort of safety stop will be used so as to prevent
plunger (203) from coming into total contact with blade edge
(205).
[0056] If the plunger is designed to additionally operate as a
rotating cutting wheel, then the catheter will have a mechanism to
rotate the plunger/cutting wheel at high speeds, typically greater
than 100 rotations per minute (rpm), preferably around 8000
rotations per minute (rpm).
[0057] As previously discussed, in some configurations, the plunger
will be mounted on a shuttle or cam mechanism to allow the operator
to adjust the protrusion of the plunger from the window. This will
allow plunger (203) to function somewhat as the stop on a safety
razor, and help prevent blade (205) from accidentally penetrating
too far into plaque during a cutting step. That is, plunger (203)
may be angled as to protrude partially outside of the window (204),
and in particular further outside window (204) than blade (205).
Thus if blade (205) starts to cut too deep, the protruding portion
of plunger (203) will then start to generate a downward deflection
force to help prevent blade (205) from cutting at a larger
depth.
[0058] The cutting edge of the blades may be optionally hardened by
an appropriate coating, such as ME-92, tungsten carbide, or other
suitable materials as taught by U.S. Pat. Nos. 4,771,774;
5,242,460; 5,312,425; 5,431,673; and 5,674,232.
[0059] In other cases, the action of blade can be facilitated by
ultrasonic vibration, laser cutting, radiofrequency electrodes, and
the like. In this case, appropriate mechanisms (i.e. a
piezoelectric ultrasonic vibrator, laser diode or optical fiber,
electrodes, etc. may also be provided in the catheter head to drive
the blade as needed. If the action of the ultrasonic, laser, or
electrode cutter is sufficiently robust enough as to make it a
spinning blade unnecessary, then the blade may either not be spun
up, or the blade rotary mechanism may be omitted, or a non-rotating
blade may be used.
[0060] In many embodiments, it will be useful to allow the location
and orientation of the catheter head to be identified by
constructing the catheter head (210), nose (201), and cutting
window/plunger region (204), (203) out of suitable combinations of
translucent and radio opaque materials, thus, for example, enabling
the region distal to the cutting window to be distinguished from
the region proximal to the cutting head by fluoroscopy or other
X-ray detection means.
[0061] In addition to fluoroscopy localization, other modalities,
such as light (optical) and sonic (ultrasonic) localization methods
may also be used. Here orientation may be facilitated by running a
fiber optic strand through the catheter tube (103) (not shown) to
an appropriate location on the catheter head, and determining the
location and orientation of the head by optical means.
Alternatively an ultrasonic transducer or pickup may be
incorporated into the catheter head.
[0062] Typically the flexible outer catheter tube (103) between the
handle (101) and the head (104) will have a length between 50 cm
and 200 cm, a diameter between 1 French (0.33 mm) and 12 French (4
mm), and will usually be between 3 French (1 mm) and 9 French (3
mm) in diameter. The catheter body will often be made from extruded
organic polymers such as polyvinylchloride, polyurethane,
polyester, polytetrafluoroethylene (PTFE), silicon rubber, or
similar materials. The catheter body may be reinforced as needed
with wires, coils, or filaments as needed to give the body
additional strength and to control rigidity and pushability.
[0063] Portions of the catheter head (104) (distal region of the
catheter) will often be rigid or partially rigid, and can be made
from materials such as metals, hard plastics, composite materials,
NiTi steel (optionally coated with titanium nitride, tantalum,
ME-92.RTM. or diamonds. Usually stainless steel or platinum/iridium
will be used. The length of the middle portion of the catheter head
may vary between about 5 to 35 mm, and will usually be between
about 10 to 25 mm; however alternative lengths (longer or shorter)
may also be used.
[0064] As previously discussed, the extreme distal end of the
catheter head (the nose) (201) will usually be made to be both
flexible and atraumatic so as to allow the catheter to be threaded
through arteries with maximum ease and minimum trauma. Because, in
this design, the nose is no longer used to store plaque, this nose
design may be optimized to accommodate the plunger, optional cams
or drive mechanisms, and also optimized to allow easy passage of
the catheter through arteries. In some cases, the distal tip will
have an inner coil construction to maximize flexibility. The
distance between the rigid part of the catheter head and the distal
end tip of the flexible catheter nose will typically be between 10
and 30 mm, but may vary as needs dictate.
[0065] The present device will often be designed to make use of a
monorail guidewire to assist in positioning the cutter to the
proper location at the target site. Usually the guidewire will have
diameters between about 0.010'' and 0.032'', usually around
0.014''. Although this guidewire may optionally pass through much
of the 50 to 200 cm length of the flexible catheter through a
hollow hole in the center of the catheter, it will usually be
desirable to have the guidewire leave catheter head proximal to the
plaque storage, window, cutting and cutting driver mechanism, and
then rejoin the catheter head after these portions have been
passed. This prevents interference with the plaque debulking
mechanism. Thus the guidewire may have a portion that is external
to the catheter head in this region.
[0066] In some embodiments, it may be desirable to protect the
portion or portions of the guidewire that is briefly external to
the catheter head by a guidewire lumen or a telescoping guidewire
lumen with a length between about 2 and 14 cm, or even longer as
needed to accommodate higher plaque storage volumes. This
telescoping guidewire lumen protects both the guidewire from
accidental cutting or entanglement with the blade and window, and
also helps protect the patient's artery or other body lumen linings
from inadvertent excessive pressure while the catheter head
traverses narrow passages.
[0067] FIG. 3 shows one example of how the catheter of the present
invention may interact with a guide wire. In order to do this,
either the catheter tube (103) and or the catheter head and nose
(210), (201) may have hollow passages or openings in order to be
compatible with such guide wires. This is shown in FIG. 3. Here a
guide wire (301) originally threaded through the hollow catheter
tube (103) exits the catheter head (210) at aperture (302). The
guide wire thus bypasses the hollow plaque storage region of the
catheter head (303) which in this example may be separated from the
hollow catheter tube (103) by a divider (304).
[0068] In this embodiment, the guidewire travels outside of the
head of the catheter (210) for a while (e.g. 5 to 15 cm) until it
reaches a first opening (305) in the catheter nose. The guide wire
may then be threaded through the catheter nose until it reaches a
second opening (306), where it may then exit. Other guide wire
configurations may be used, or alternatively, no guide wire at all
may be used.
[0069] As shown in FIG. 4A, once the catheter head has been
maneuvered to the appropriate target zone, the adjustable angle
nose (201) is angled or drooped, and the plug (203) is pushed
distally (201), opening up window (204) and exposing the window
knife edge (205). The angled or drooped nose (201) contacts the
opposite wall of artery or body lumen (401), providing pressure to
force or "urge" window (204) and knife edge (205) against the wall
of the artery (402) and against the target plaque (403). The
operator can then advance (more) the catheter head (210) forward
(distally) by applying forward pressure to the catheter tube (103)
or advancing some other type of drive mechanism.
[0070] Blade (205) shaves off some of this plaque (403) and this
removed plaque (404) enters the hollow cavity of catheter head
(210). Helical screw (207) can then act to move this plaque further
back into the storage cavity. As previously discussed, plunger
(203) can optionally be rotated by a cam mechanism and advanced
partially out of the window (205) in order to provide greater
control over the depth of the cut by blade (205).
[0071] As shown in FIG. 4B, the dangling plaque (404) can also be
trimmed by moving plunger (203) proximally back into the catheter
head (210) thus closing or partially closing window (204). The
plunger forces the dangling plaque (404) up against the knife edge
(205) pinching or cutting the dangling plaque. This severed plaque
(405) then enters the hollow capillary head where it can be moved
to the back by an optional helical screw (207), suction, or other
mechanism.
[0072] As previously discussed, in alternative embodiments, plunger
(203) may be a rotating plunger that also has its own cutting head
along the edge of the plunger facing the window. Alternatively
plunger (203) may have an edge configuration designed to shield or
partially shield blade (205) from inadvertent contact with body
lumens when the window (204) is closed or partially closed by the
plunger (203). The plunger mechanism may additionally have various
cams or stops designed to place the plunger at the appropriate
angle and orientation necessary to perform its function.
[0073] FIG. 5 (501) to (506) shows various alternate blade (205)
and window (204) configurations that may be used with the
device.
* * * * *