U.S. patent application number 12/392220 was filed with the patent office on 2009-06-18 for catheter with open faced end portion.
Invention is credited to William M. Appling, Theodore J. Beyer, Carol L. Lancette.
Application Number | 20090157051 12/392220 |
Document ID | / |
Family ID | 39360608 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090157051 |
Kind Code |
A1 |
Appling; William M. ; et
al. |
June 18, 2009 |
Catheter with open faced end portion
Abstract
A vascular access catheter that has a substantially distal end
portion that has a distal tip. The distal end portion has a sloped
face in the distal portion of the catheter, an outflow lumen
aperture, and a second inflow lumen aperture. The outflow lumen
aperture is substantially completely open in the sloped face and
exits the distal portion adjacent the distal tip. The catheter has
a guidewire lumen that is located at least in the region of the
distal portion of the catheter and is capable of receiving a
guidewire. The guidewire lumen has a proximal aperture and a distal
aperture that extends distally of the outflow lumen aperture. The
guidewire distal aperture exits at the distal most edge of the
distal end portion. The guidewire lumen may extend a partial length
of the catheter or substantially the entire length of the catheter.
The catheter distal portion may be substantially straight or
curved.
Inventors: |
Appling; William M.;
(Granville, NY) ; Beyer; Theodore J.; (Queensbury,
NY) ; Lancette; Carol L.; (Hudson Falls, NY) |
Correspondence
Address: |
ANGIODYNAMICS, INC.
603 QUEENSBURY AVENUE
QUEENSBURY
NY
12804
US
|
Family ID: |
39360608 |
Appl. No.: |
12/392220 |
Filed: |
February 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11557369 |
Nov 7, 2006 |
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12392220 |
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Current U.S.
Class: |
604/528 |
Current CPC
Class: |
A61M 25/008 20130101;
A61M 25/0068 20130101; A61M 25/0071 20130101; A61M 2025/0031
20130101; A61M 25/003 20130101; A61M 2025/0037 20130101 |
Class at
Publication: |
604/528 |
International
Class: |
A61M 25/09 20060101
A61M025/09 |
Claims
1-27. (canceled)
28. A method of inserting a vascular access catheter into a vessel,
wherein the method comprises: a. providing a vascular access
catheter, wherein the catheter comprises a proximal portion and a
distal portion, wherein the distal portion has a distal end
portion, and wherein the distal end portion has a distal tip and is
substantially sloped with a sloped face; and at least two lumens,
wherein each lumen has at least one aperture that communicates
between the lumen and the exterior of the lumen: and a first lumen
aperture, wherein the first lumen aperture exits the distal portion
adjacent the distal tip, and wherein the first lumen aperture is
substantially completely open in the sloped face; and a third lumen
located at least in the region of the distal portion, wherein the
third lumen is capable of receiving a guidewire, and wherein the
third lumen has a proximal aperture and a distal aperture, and
wherein the distal aperture of the third lumen exits the distal
portion distally of the first lumen aperture; and b. inserting the
guidewire into a vessel in a patient body; and c. inserting a
guidewire into the distal aperture of the third lumen; and d.
advancing the guidewire through the third lumen and into the first
lumen; and e. inserting the catheter into a vessel in a patient
body over the guidewire; and f. positioning the distal portion of
the catheter at a desired location; and g. removing the guidewire
from the third lumen.
29. The method of claim 28, further comprising providing a
catheter, wherein the third lumen exits at the distal most edge of
the sloped distal end portion.
30. The method of claim 28, further comprising providing a
catheter, wherein the third lumen extends a partial length of the
catheter.
31. The method of claim 28, further comprising providing a
catheter, wherein the catheter comprises a substantially curved
distal portion.
32. The method of claim 31, further comprising straightening the
curved distal portion of the catheter upon insertion of the
guidewire into the third lumen.
33. The catheter of claim 28, wherein the distal portion is
substantially bent in its unstressed state.
34. The method of claim 33, further comprising straightening the
bent distal portion of the catheter upon insertion of the guidewire
into the third lumen.
35. The method of claim 28, further comprising providing a
catheter, wherein the catheter is a hemodialysis catheter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0004] Not Applicable
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] The present invention pertains to the field of medical
devices. More particularly, the present invention relates to blood
treatment catheters and a method of using such catheters.
[0007] 2. Description of the Related Art Including Information
Disclosed Under 37 CFR 1.97 and 1.98
[0008] Hemodialysis is a method for removing waste products such as
potassium and urea from the blood, such as in the case of renal
failure. During hemodialysis, waste products that have accumulated
in the blood because of kidney failure are transferred via mass
transfer from the blood across a semi permeable dialysis membrane
to a balanced salt solution. The efficiency of a hemodialysis
procedure depends on the amount of blood brought into contact with
the dialysis membrane. A flow of 250 milliliters of blood per
minute under a pressure gradient of 100 millimeters of mercury is
considered a minimum requirement for adequate dialysis. Over the
past several years, flow rates between 350 milliliters per minute
and 400 milliliters per minute have become common.
[0009] The long hours and the frequency of the dialysis treatment
in patients with renal failure require reliable, continued access
to the venous system for blood exchange. Long-term venous access
mechanisms commonly used for hemodialysis treatment include
vascular access ports, dialysis grafts, and hemodialysis catheters.
One type of blood treatment catheter that is well-known in the art
is a dual or triple-lumen hemodialysis catheter. These catheters
are designed to provide long-term access to the venous system for
dialysis. The dual-lumen catheter typically has an inflow lumen for
withdrawing blood to be treated from a blood vessel and an outflow
lumen for returning cleansed blood to the vessel. The distal
segment of the catheter is preferably positioned at the junction of
the superior vena cava and right atrium to obtain a blood flow of
sufficient volume to accommodate dialysis treatment requirements.
This allows blood to be simultaneously withdrawn from one lumen, to
flow into the dialysis circuit, and be returned via the other
lumen. Triple lumen catheters function in a similar manner but have
an additional smaller lumen which may be used for guidewire
insertion, administration and withdrawal of fluids such as drugs or
blood sampling, and for injection of contrast media required for
imaging procedures.
[0010] To optimize blood flow rates during dialysis and reduce
treatment times, catheters have been designed to maximize the
cross-sectional lumen area of the inflow and outflow lumens. It is
well known in the art that blood flow rates are negatively impacted
if the cross-sectional area of the lumens does not remain
essentially consistent and as large as possible throughout the
entire length of the catheter from the proximal portion of the
catheter to the distal portion of the catheter. Catheters with
large, consistent luminal space typically have exit ports with
blunt or flat-faced open tips, so as not to compromise the luminal
area. Typically the exit port at the distal end of the catheter is
cut at a 90 degree angle to the axis of the catheter.
[0011] While blunt, open ended catheters maintain optimal flow
rates, they are difficult to insert into the patient because of
their blunt leading ends. An introducer sheath will often be used
to facilitate insertion. The introducer sheath has a dilating tip
which is easily advanced through the track and into the vessel. The
sheath has a large lumen into which the blunt-tipped catheter is
inserted and advanced into the vessel. Although an introducer
sheath may facilitate catheter placement, use of a sheath has
several disadvantages. A sheath increases the risk of air embolism
due to the presence of air gaps between the sheath and catheter. In
addition, procedures that use an introducer sheath result in an
enlarged insertion track due to the larger diameter of the sheath
relative to the catheter. The use of a sheath also increases
procedure time and costs.
[0012] A guidewire insertion technique is therefore often the
preferred insertion technique for dialysis catheter placement. A
guidewire is a thin, flexible wire that is usually made of
stainless steel and has an atraumatic tip. A guidewire is typically
inserted into a lumen of a dual or triple lumen catheter and then
the catheter is advanced over the guidewire through the tissue
track and into the vessel. The guidewire also provides additional
stiffness or reinforcement in the wall of a catheter, to prevent
kinking or accordianing of the catheter shaft as it is advanced
through a tissue track and into a vessel.
[0013] If a guidewire is used for insertion of a blunt-end catheter
with a large distal end opening, excess space will exist between
the outer diameter of the guidewire and the inner diameter of the
catheter lumen. A close fit between the lumen and the inserted
guidewire is not dimensionally possible, thus leaving an annular
gap between the guidewire and the distal opening of the catheter
lumen. The excess annular space causes the leading distal edge of
the catheter to accordion proximally over the guidewire during
insertion, resulting in difficulties in advancing the catheter into
the vessel. The distal portion of the catheter may grab or snare
tissue as the practitioner attempts to advance the catheter into
and through the vessel. This can increase procedure time, prevent
the practitioner from reaching the intended target site within a
patient vessel, or potentially cause other complications.
[0014] To overcome insertion difficulties common with inserting
blunt tipped catheters, dialysis catheters have been designed with
conical tapered distal portions that are narrower compared to the
proximal portion of the catheter. The conical tip acts as a dilator
to facilitate advancement of the catheter through the tissue track
and into the vessel. These conical tip designs may include a
guidewire lumen that exits from the distal tip of the catheter
through a guidewire opening of reduced diameter, typically 0.037
inches.
[0015] While conical, tapered tip designs address the problems
associated with inserting blunt tip full lumen distal end designs,
they are disadvantageous in that they do not allow for optimum flow
rates due to the reduced lumen diameter at the distal tip. To
overcome reduced flow rates, conical, tapered tip catheters have
been designed with distal side facing ports or apertures cut
through the catheter sidewall. The ports are located proximal to
the conical tapered section and accordingly provide an exit channel
from the lumen at a location where the cross-sectional area of the
lumen has not been reduced.
[0016] Using side holes or apertures eliminates the problems of
reduced flow rates but side-facing apertures are more likely to
occlude than distally facing apertures. Those side holes located
adjacent to the vessel wall are more likely to become blocked by
the vessel wall, and are thus prone to clot-formation. In addition,
the presence of side holes compromises the effectiveness of a fluid
lock. A fluid lock, as known in the art, is used to prevent clot
formation within the catheter between dialysis sessions. Typically,
a heparin-saline fluid solution is infused into the full length of
the catheter lumens. The fluid lock will only be effective up to
the first proximal side hole, where the fluid will exit from the
catheter and be replaced by blood. In the absence of the
heparin-saline fluid solution, a portion of the lumen distal of the
first side hole will become occluded by clot formation,
complicating future dialysis sessions.
[0017] Another common complication of dialysis catheters is
occlusion of the inflow and outflow apertures due to contact
between the catheter and the vessel wall at the location of the
apertures. During dialysis, negative pressure is generated within
the inflow lumen in order to draw blood from the vessel through the
lumen and into the dialysis machine. The suction created by the
negative pressure may cause the catheter to move away from the
center of the vessel and into contact with the vessel wall. The
vessel wall essentially blocks the aperture, preventing further
blood from being drawn into the inflow lumen. Although not as
common, the outflow apertures may also come to rest up against the
vessel wall, resulting in occlusion.
[0018] Thus, there exists a need in the art for a dual or triple
lumen hemodialysis catheter that has a dilating distal tip that is
not reduced in lumen cross-sectional area compared to the rest of
the lumen. Such a lumen would be able to maintain consistent and
optimal blood flow rates throughout the entire length of the
catheter, eliminating the need for side hole ports. The catheter
would have one lumen capable of receiving a guidewire that can
provide enhanced guidewire tracking along various lengths of the
catheter, thereby eliminating the need for an introducer sheath.
The catheter would be designed to prevent occlusion of the blood
lumen apertures by having a distal end shape that creates a barrier
between the blood lumens and vessel wall.
[0019] A hemodialysis catheter has not yet been proposed that
solves all of the above-mentioned problems. The present invention
addresses problems with prior art catheters by providing a
hemodialysis catheter that has at least two lumens, each with at
least one aperture, and a distal portion that has one lumen with a
substantially open sloped face distal end portion with a distal tip
and consistent cross-sectional area compared to the rest of the
lumen of the catheter, which allows for maximum blood flow. The
catheter also has a third lumen located adjacent the distal tip
that is capable of receiving a guidewire. The guidewire aperture
and the sloped face of the distal end portion facilitate insertion,
without the use of an introducer sheath. The luminal cross-section
area is maintained for the entire length of the catheter,
eliminating the need for side holes, and thereby avoiding problems
associated with compromised fluid lock and resulting side hole
occlusion. The catheter 1 may optionally include a curved or bent
distal end shape to prevent contact between the lumen apertures and
the vessel wall.
[0020] Accordingly, it is a purpose of the present invention to
provide a hemodialysis catheter that may have two or three lumens
and a sloped open-faced distal end portion that provides for
optimal blood flow rates by maintaining a uniform cross-sectional
area throughout the lumen, eliminating the need for attachments or
additional steps, thereby minimizing procedure time and improving
patient treatment outcomes.
[0021] A further purpose of this invention is to provide a catheter
that maintains the cross-sectional area of the blood lumen of the
catheter without increasing the outer diameter of the catheter.
[0022] A further purpose of this invention is to provide a
transitional guidewire lumen that is positioned at the distal most
edge of the sloped distal end portion of the catheter that does not
cause the overall outer diameter of the catheter to be
increased.
[0023] A further purpose of this invention is to provide a catheter
that is capable of receiving a guidewire in a third lumen that is
designed for optimal guidewire tracking without requiring the use
of an introducer sheath. The lumen may extend a partial length of
the catheter, where it may be joined to another lumen, or it may
extend substantially all the way through to the proximal end of the
catheter, which may be useful for injections or infusion of drug
treatments.
[0024] A further purpose of this invention is to provide a catheter
that minimizes occlusion of the lumen apertures of the catheter by
providing a substantially curved distal portion that abuts against
the vessel wall while the catheter is deployed in a vessel. The
abutting curved distal portion acts to guard one of the lumen
apertures of the catheter from being occluded, which in turn,
maintains maximum blood flow.
[0025] A further purpose of this invention is to provide a catheter
that has a distal portion that allows for increased ease of
insertion of the catheter into a vessel. The insertion is
facilitated by straightening or flattening the distal portion of
the catheter from a substantially curved to a straight
configuration, which causes less resistance upon insertion. The
distal portion of the catheter is more flexible, compared to the
rest of the catheter, which helps to facilitate straightening of
the distal portion. The flexibility of the distal portion of the
catheter allows the distal portion to return to its original
configuration after the guidewire is removed.
[0026] It is a further purpose of this invention to provide a
catheter that maximizes flow rates without requiring side hole
ports.
[0027] It is yet another purpose of this invention to provide a
non-conical distal end portion catheter that may be placed without
the use of an introducer sheath.
[0028] Various other objectives and advantages of the present
invention will become apparent to those skilled in the art as more
detailed description is set forth below. Without limiting the scope
of the invention, a brief summary of some of the claimed
embodiments of the invention is set forth below. Additional details
of the summarized embodiments of the invention and/or additional
embodiments of the invention may be found in the Detailed
Description of the Invention.
BRIEF SUMMARY OF THE INVENTION
[0029] The present invention is advantageous over the prior art
because it provides a dual or triple lumen catheter with a
substantially open lumen aperture at the distal portion of the
catheter that allows for optimal blood flow by maintaining the
lumen cross-sectional area throughout the entire catheter without
increasing the outer diameter of the catheter. The need for
supplemental side holes is eliminated because the cross-sectional
area of the blood flow lumens is maintained.
[0030] The vascular access catheter of the present invention has a
proximal portion and a distal portion. The distal portion of the
catheter has a distal tip and a distal end portion, which is
substantially sloped with a sloped face. The catheter includes at
least two lumens, each lumen having at least one aperture that
communicates between the lumen and the exterior of the lumen. The
catheter has a first lumen aperture, which is substantially
completely open in the sloped face and exits the distal portion
adjacent the distal tip. A third lumen is located at least in the
region of the distal portion of the catheter. The third lumen is
capable of receiving a guidewire and has a proximal aperture and a
distal aperture which exits the distal portion distally of the
first lumen aperture.
[0031] The first lumen may function as an outflow lumen, and the
second lumen may function as an inflow lumen, but these
functionalities may be interchanged between the first lumen and the
second lumen. The inflow lumen aperture of the catheter is spaced
proximally of the outflow aperture to minimize re-circulation. The
cross-sectional area of each lumen is substantially uniform
throughout the entire length of the catheter. The catheter
optionally provides a substantially curved distal portion which
serves as a guard against occlusion of the catheter lumens.
[0032] The third guidewire lumen extends distally adjacent the
substantially open outflow lumen aperture, either partially or
substantially completely throughout the entire catheter, thereby
providing enhanced guidewire tracking capabilities and eliminating
the need for an introducer sheath. The guidewire lumen also allows
the curved distal portion of the catheter to be straightened for
easier insertion. The distal end portion of the catheter has a
forward-facing sloped surface profile, instead of a blunt face, to
facilitate catheter insertion and advancement, as well as to assist
in orienting the catheter end portion once in a vessel.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0033] The foregoing advantages and features, as well as other
advantages and features, will become apparent with reference to the
description and accompanying figures below, which are included to
provide an understanding of the invention and constitute a part of
the specification, in which like numerals represent like elements,
and in which:
[0034] FIG. 1 is a plan view of the catheter and a partial
cross-sectional view of the distal portion of the catheter, in
accordance with the present invention.
[0035] FIG. 2A is an enlarged partial cross-sectional view of the
distal portion of the catheter of FIG. 1, in accordance with the
present invention.
[0036] FIG. 2B illustrates three different cross-sectional views of
the catheter shaft and one cross-sectional end view of the catheter
of FIG. 2A along lines A-A, B-B, C-C, and D-D, respectively, in
accordance with the present invention.
[0037] FIG. 3A is an enlarged partial cross-sectional view of an
additional embodiment of the catheter with a curved distal portion,
in accordance with the present invention.
[0038] FIG. 3B is a cross-sectional end view of the curved distal
portion of the catheter of FIG. 3A, in accordance with the present
invention.
[0039] FIG. 4A is a partial cross-sectional view of an additional
embodiment of the catheter with a curved distal portion, in
accordance with the present invention.
[0040] FIG. 4B is a cross-sectional end view of the curved distal
portion of the catheter of FIG. 4A, in accordance with the present
invention.
[0041] FIG. 5A is a partial cross-sectional side view of the
catheter of FIGS. 3A and 3B, while deployed inside a vessel with a
guidewire inserted into the catheter, in accordance with the
present invention.
[0042] FIG. 5B is a partial cross-sectional side view of the
catheter of FIG. 5A after the guidewire has been removed from the
catheter, in accordance with the present invention.
[0043] FIG. 6A is a plan view of a triple lumen catheter and a
partial cross-sectional view of the distal portion, in accordance
with the present invention.
[0044] FIG. 6B illustrates two different cross-sectional views of
the catheter shaft of FIG. 6A, along lines G-G and H-H,
respectively, in accordance with the present invention.
[0045] FIG. 7A is a plan view of an additional embodiment of a
triple lumen catheter and a partial cross-sectional view of the
distal portion, in accordance with the present invention.
[0046] FIG. 7B illustrates two different cross-sectional views of
the catheter of FIG. 7A at the catheter shaft, along lines I-I and
J-J, respectively, in accordance with the present invention.
DETAILED DESCRIPTION
[0047] The following detailed description should be read with
reference to the drawings, in which like elements in different
drawings are identically numbered. The drawings, which are not
necessarily to scale, depict selected preferred embodiments and are
not intended to limit the scope of the invention. The detailed
description illustrates by way of example, not by way of
limitation, the principles of the invention.
[0048] The present invention pertains to a hemodialysis catheter
and a method of inserting the catheter in the body of a patient.
The hemodialysis catheter of the present invention is illustrated
in FIGS. 1-7.
[0049] FIG. 1 illustrates one embodiment of the hemodialysis
catheter of the present invention. The unitary catheter 1 has a
proximal portion 3 and a distal portion 5. In this embodiment, the
distal portion 5 of the catheter 1 is substantially straight. The
proximal portion 3 of the catheter 1 is comprised of a bifurcate
49, a suture ring 47 coaxially arranged around the distal portion
of the bifurcate 49, a pair of extension tubes 50, 51, extension
tube clamps 55, catheter hub connectors 53 for connection to a
dialysis machine, and a catheter shaft 7 which extends from the
bifurcate 49 to the distal tip 8 at the distal portion 5 of the
catheter 1.
[0050] Catheter shaft 7 is a tubular structure comprised of an
outer wall 16 and two longitudinal lumens 19 and 9 extending
substantially the entire length of the catheter shaft 7. Lumen 19
is in fluid communication with extension tube 51, and lumen 9 is in
fluid communication with extension tube 50. Both extension tubes
50, 51 communicate through bifurcate 49. Blood is typically
withdrawn from the vessel into lumen 19 where it is passed through
the extension tube 51 into the dialysis machine. Blood is returned
to the patient through extension tube 50 into lumen 9 which exits
through the distal aperture 11 into the vessel.
[0051] The outer diameter of the catheter 1 is approximately 0.203
inches, although other diameter catheters are within the scope of
this invention. The usable length of the catheter 1, as measured
from the distal end of bifurcate 49 to the distal tip 8, is between
approximately 20 cm to 55 cm, depending on the patient's anatomy
and physician preference. Preferably, the catheter 1 usable length
is between approximately 32 and 36 cm.
[0052] The catheter 1 of the present invention is a unitary
catheter composed of carbothane, but any suitable material may be
used, such as, but not limited to, polyurethane or silicone. The
catheter 1 of the present invention may also contain a radiopaque
material to enhance visibility under fluoroscopy. The catheter
shaft 7 is preferably more flexible at its distal portion 5 than
its proximal portion 3 because the distal portion 5 is of a reduced
diameter and is formed with less material, compared to the proximal
portion 3. The catheter shaft 7 may optionally be comprised of
materials of different durometers to produce a shaft 7 with
enhanced flexibility at the distal portion 5. It is preferable that
the catheter shaft 7 be stiffer at the proximal portion 3 outside
of the patient's body for durability and more flexible at the
distal portion 5 to facilitate insertion of the catheter 1 and to
provide a catheter 1 with an atraumatic tip, when placed within a
vessel.
[0053] The catheter 1 has an inflow lumen 19 that exits the distal
portion 5 of the catheter 1 through an inflow aperture 21. The
inflow lumen 19 is typically used for withdrawal of blood from the
patient. The inflow aperture 21 is forward-facing, as defined by an
angle greater than about 90 degrees proximally from the axis of the
catheter 1. The catheter 1 also has an outflow lumen 9 which is
typically used for delivering cleansed blood back into the
patient's circulatory system. Blood exits the distal portion 5 of
the catheter 1 through outflow aperture 11, located distally of the
inflow aperture 21. The two lumens 9 and 19 are separated along
their longitudinal length by dividing wall 17. Although designated
herein as inflow and outflow lumens, dialysis may be performed by
reversing the blood flow through the lumens. Hence, the terms first
lumen and second lumen may also be used herein to designate the
interchangeability of the outflow and inflow lumens,
respectively.
[0054] The catheter 1 has a third guidewire lumen 37 that is
located at least in the region of the distal portion 5. The
guidewire lumen 37 extends proximally from guidewire exit aperture
39 to proximal guidewire aperture 41 where lumen 37 terminates
within outflow lumen 9. The guidewire lumen 37 is capable of
slidably receiving a guidewire (not shown). The guidewire lumen 37
provides a guidewire track for the guidewire to facilitate
insertion of the catheter 1 through tissue into the target vessel.
In this embodiment, the guidewire lumen 37 extends a partial length
of the catheter 1. For instance, the length of the guidewire lumen
37 may be between approximately 3 mm and 10 mm, and preferably
between approximately 6 mm and 7 mm in length. The inner diameter
of guidewire lumen 37 may be approximately 0.037 inches so as to
accommodate a guidewire with an outer diameter of approximately
0.035 inches.
[0055] The distal tip 8, outflow aperture 11, and the guidewire
exit aperture 39 define the sloped distal end portion 35 of the
distal portion 5 of the catheter 1. Sloped, as it pertains to the
description herein, means that distal end portion 35 has an edge
that is not at a perpendicular angle to the axis of the catheter 1,
and could include end portions 35 defined by flat, arcuate, or
extended arcuate surfaces. The sloped distal end portion 35 which
extends from the proximal most edge of the outflow lumen aperture
11 to the distal most edge of the third lumen 37 is approximately 5
mm, although the length will vary based on the angle of the slope.
The angle of the sloped distal end portion 35 may between
approximately 15 degrees and 75 degrees from the axis of the
catheter 1. Preferably, the sloped distal end portion 35 is
approximately 30 degrees relative to the axis of the catheter
1.
[0056] In a key aspect of this invention, the sloped distal end
portion 35 acts as a dilator to provide enhanced insertion and
tracking functionality without compromising flow rates, as will be
explained in greater detail below.
[0057] Distal portion 5, defined as the length between the distal
most edge of the inflow aperture 21 and the distal most edge of the
guidewire exit aperture 39, is approximately 2.5 cm, and in the
depicted embodiment in FIG. 1, is substantially straight. The
length between the distal most edge of the inflow aperture 21 and
the proximal most edge of the outflow lumen aperture 11 is
approximately 2 cm, so as to provide sufficient separation between
the two lumens to minimize re-circulation of blood during dialysis.
Recirculation is a complication of dialysis in which treated blood
exiting from the outflow aperture 11 is pulled back into the
catheter 1 through the inflow aperture 21 and re-processed by the
dialysis machine. Recirculation reduces the efficiency of the
cleansing process and results in inadequate dialysis if
recirculation rates are too high. By spacing the inflow aperture 21
and outflow aperture 11 sufficiently apart, the recirculation rate
during treatment is reduced to an acceptable level.
[0058] FIG. 2A illustrates an enlarged sectional view of the distal
portion 5 of the catheter shaft 7 of FIG. 1. The outer wall 16 of
the proximal portion 3 of the catheter shaft 7 surrounds an outflow
lumen 9 and an inflow lumen 19, which are separated by a dividing
wall 17. The outflow lumen 9 extends from the proximal most end of
the catheter shaft 7 to aperture 11, located in sloped distal end
portion 35. Inflow lumen 19 extends distally from the proximal most
end of catheter shaft 7 to inflow aperture 21.
[0059] The distal portion 5 of the catheter 1 includes a sloped
distal end portion 35, which is comprised of distal tip 8,
guidewire exit aperture 39, and outflow lumen aperture 11. The
sloped profile of distal end portion 35 performs several key
functions. The forward-facing slope provides a tapered leading edge
to facilitate insertion and advancement of the catheter 1. The
forward-facing orientation of the slope is also advantageous in
that it is angled away from the vessel wall to minimize engagement
with the vessel wall, once inserted. The distal-most leading edge
of the sloped end portion 35 terminates in a guidewire exit
aperture 39 for optimized guidewire tracking. Distal end portion 35
also includes a forward-facing, full size outflow lumen 11. Thus,
in a key aspect of the invention, the sloped distal end portion 35
combines the features of a distal end profile capable of tracking
over a guidewire and dilating the insertion track as well as
minimizing vessel wall contact with an aperture that is not reduced
in cross-sectional area.
[0060] The partial transitional guidewire lumen 37 that is adapted
for insertion of a guidewire (not shown), allows for ease of
insertion of the guidewire into the catheter 1 and also allows ease
of insertion of the catheter 1 into a vessel over the guidewire.
The guidewire lumen 37 has an inner diameter of approximately 0.037
inches, which closely fits around an inserted guidewire of
approximately 0.035 inches. These dimensions allow the guidewire to
slide within the lumen 37, while eliminating space between the
outer diameter of the guidewire and the inner diameter of the lumen
37. This enhanced guidewire tracking prevents tissue from being
snagged during advancement of the catheter 1 into a target
location, and it provides a dilating function, thereby reducing
trauma and tissue disruption to the vessel. The guidewire and
catheter 1 may therefore be easily inserted into a vessel without
requiring the use of an introducer sheath. Eliminating the
introducer sheath is advantageous in several aspects, including
reduced procedure time and costs, and minimized risk of air
embolism due to absence of air gaps between the sheath and the
catheter 1.
[0061] The transitional partial guidewire lumen 37 is also
advantageous because, in addition to providing enhanced guidewire
tracking, the outer diameter of the catheter 1 does not have to be
increased to accommodate the partial lumen 37 adjacent to the
outflow lumen aperture 11 at the distal most edge of the distal tip
8. This allows the cross-sectional area of the outflow lumen 9 to
be maintained and provides for maximum blood flow.
[0062] FIG. 2B illustrates four different cross-sectional views of
the catheter shaft 7 of the first embodiment. The lumen
configuration of the catheter 1 transitions from a double-D lumen,
illustrated along line A-A, to a single-D lumen, illustrated along
line B-B, to a single round outflow lumen 9 illustrated along line
C-C, finally ending in a single round outflow lumen 9 at the distal
most tip of the catheter 1, with a guidewire lumen 37 located
adjacent the outflow lumen 9, which is illustrated along line
D-D.
[0063] The first cross-sectional view, A-A, illustrates the
double-D lumen configuration of the catheter shaft 7 which extends
to just proximal of line B-B, where the inflow lumen 19 terminates
at aperture 21. Although the lumens of the catheter 1 of the
present invention preferably have a double-D configuration, the
catheter 1 may have any suitable cross-sectional lumen shape as
required for the particular use of the catheter 1. The advantage of
a double-D lumen configuration is that it allows for maximal flow
rates for a catheter 1 circular in cross-sectional profile, which
fact is well known in the art. The outflow lumen 9 and the inflow
lumen 19 are shown separated by a dividing wall 17. The outflow
lumen 9 has an inner wall 13. The inflow lumen 19 has an inner wall
25. As illustrated in line A-A, the dividing wall 17 has a width of
approximately 0.144 inches. In this embodiment, the preferred
height of each double-D lumen is approximately 0.064 inches.
[0064] A cross-sectional view of line B-B in the distal portion 5
of the catheter 1 is also illustrated. Outer wall 16 and inner wall
25 define the inflow lumen 19, which is shown as an end view,
terminating proximally of line B-B. The outflow lumen 9 extends
distally of the inflow lumen 19, which terminates at inflow
aperture 21, proximal to line B-B. At the termination point of
inflow aperture 21, the double-D lumen also terminates and is
continued as a single-D lumen 9.
[0065] At line C-C, the single-D shaped lumen has transitioned to a
single round shaped outflow lumen 9. In this view, the transitional
wall 14 represents the inner wall of the dividing wall 17 of the
outflow lumen 9 at the double-D lumen section. At line C-C, the
outflow lumen 9 has an inner diameter of approximately 0.095 inches
and an outer diameter of approximately 0.140 inches. The rounded
outer profile of the catheter shaft 7 at line C-C is of a smaller
outer cross-sectional diameter than the cross-sectional diameter of
the catheter shaft 7 at line B-B, which measures 0.203 inches. The
reduced diameter facilitates insertion and advancement of the
distal end of the catheter 1 through the tissue track and into the
vessel.
[0066] A cross-sectional end view of the catheter 1, as taken along
line D-D, is also illustrated. The cross-sectional end view, taken
along lines D-D of FIG. 2B illustrates the guidewire lumen 37.
Lumen 37 has a substantially circular shape defined by an inner
wall 43. The inner diameter of the guidewire lumen 37 is
approximately 0.037 inches. The guidewire lumen 37 is capable of
receiving a guidewire that is approximately 0.035 inches.
[0067] Lumen 37 is surrounded by an expanded guidewire wall segment
100 which separates lumen 37 from outflow lumen 9. Wall segment 100
may be formed using several techniques well known in the art
including re-forming existing shaft material, or using a
supplemental tip-forming or a molding process. In a key aspect of
the invention, lumen 37 is positioned within guidewire wall segment
100 to ensure that the cross-sectional area of outflow lumen 9 at
the sloped distal end portion 35 is equivalent to the proximal
portion 3 of the lumen 9.
[0068] The catheter 1 of the present invention is advantageous
because although the profiles of the lumens 19 and 9 change at
different sections of the catheter 1, the cross-sectional lumen
areas are maintained throughout the length of the catheter 1.
Specifically, the cross-sectional area of each of the double-D
lumens, taken along line A-A, which is approximately 0.00702
inches.sup.2, is substantially equal to the cross-sectional area of
the catheter 1 taken along line D-D, which is approximately 0.00708
inches.sup.2. This substantially equivalent cross-sectional area
allows for optimal and consistent blood flow within the catheter 1
throughout treatment of the patient.
[0069] In addition, unlike current unitary catheter designs, the
catheter 1 of the current invention allows for insertion over a
guidewire utilizing a leading distal end guidewire aperture without
increasing the overall diameter of the catheter 1 and without
compromising the cross-sectional luminal area of the outflow lumen
9. The cross-sectional diameter of the sloped distal portion 35
taken along the axis of the catheter shaft 7 is preferably 0.160
inches, but may range from 0.150 to 0.180 inches. The reduced
cross-sectional diameter of the outflow lumen 9 at line D-D, which
is approximately 0.043 inches less that the proximal portion 3 of
the catheter shaft 7, which has a cross-sectional diameter of
approximately 0.203 inches, which thus facilitates insertion and
advancement of the catheter 1 into a patient's body without
compromising the cross-sectional luminal area of the outflow lumen
9.
[0070] Accordingly, in one aspect of the invention, a catheter 1
with a non-conical sloped dilating distal portion 35 is provided
that maintains a consistent, uniform luminal area throughout the
entire length of the catheter shaft 7. The substantially completely
open sloped face geometry of the outflow lumen aperture 11 of the
distal tip 8 allows for maximum blood flow because the
cross-sectional area of the outflow lumen 9 is maintained from the
proximal portion 3 to the distal portion 5 of the catheter 1, while
the outer diameter of the catheter 1 is not increased. Because of
its size and orientation, the outflow lumen aperture 11 is not
likely to occlude, compared with typical conical-tapered or blunt
tip catheters with smaller side wall lumen openings.
[0071] FIG. 3A illustrates another embodiment of the catheter 1 of
the present invention. In this embodiment, the catheter shaft 7 has
a double-D lumen configuration at its proximal portion 3, which
transitions to a circular configuration with inflow and outflow
apertures, similar to the embodiment illustrated in FIG. 1. The
catheter shaft 7 of FIG. 3A is different from FIG. 1 in that it has
a substantially curved distal portion 5 instead of a straight
distal portion 5. The distal portion 5 of catheter shaft 7 may have
any suitable curved shape configuration, including, but not limited
to a curved, bent or semi-helical shape.
[0072] As further distinguished from the first embodiment of
catheter 1 illustrated in FIGS. 1 and 2, the distal portion 5 of
the catheter 1, is defined by a guard portion 29. The guard portion
29 has an apex 31. The apex 31 is located at the outermost point of
the guard portion 29 and is equal to or greater in height than the
outer wall 16 of the inflow aperture 21. The guard portion 29 is
also defined by an inner angle 33 opposite the inflow apex 31. The
inner angle 33 may be between approximately 45 degrees and 135
degrees. Preferably, the inner angle 33 of the guard portion 29 is
equal to or greater than about 90 degrees, depending on the
curvature of the guard portion 29. Most preferably, the inner angle
is approximately 90 degrees. The curved distal portion 5 may have
substantially straight portions on either side of the inner angle
33, or the curved distal portion 5 may be a substantially
continuous series of arcuate arcs.
[0073] FIG. 3B illustrates the distal portion 5 of the catheter 1
of FIG. 3A along line E-E. The apex 31 of the guard portion 29 is
illustrated. The distal end of inflow aperture 21 is partially
visible, being protected by apex 31. The outer wall 15 of the
distal portion 5 of the catheter 1 transitions into a shared outer
wall 18 of the outflow lumen 9 and guidewire lumen 37, which has an
inside wall 43. The transition point of the guidewire aperture 41,
where the guidewire lumen 37 joins the outflow lumen 9, is visible
inside of the outflow lumen 9.
[0074] As shown in FIG. 3B, the space between the apex 31 and the
outer wall 16 of the inflow aperture 21 functions as a guard to
prevent aperture 21 from moving up against the vessel wall and
potentially occluding the inflow aperture 21 as long as the height
of the apex 31 is equal to or greater than the height of the outer
wall 16 of inflow aperture 21. When the negative pressure of a
blood draw into the inflow lumen causes the catheter 1 to move
toward the vessel wall, the apex 31 of the guard 29 will abut up
against the vessel wall rather than the inflow aperture 21. More
specifically, the difference in height between the apex 31 of the
guard portion 29 and the proximal most portion of the inflow
aperture 21 helps the guard portion 29 to act as a guard and
prevent inflow aperture 21 from contacting or resting against the
vessel wall. Guard portion 29 thus functions to ensure that
aperture 21 remains positioned away from the vessel wall so as to
avoid being partially or completely blocked and compromising
outcome of the treatment session.
[0075] Apex 31 provides an additional clinical advantage over prior
art dialysis catheters. Apex 31, with its extended height, provides
a separating barrier between the inflow aperture 21 and the outflow
aperture 9, to further minimize mixing cleansed and uncleansed
blood during a dialysis session and decreasing recirculation
problems.
[0076] The guidewire lumen 37 shared outer wall 18, combined with
the forward-facing orientation of the sloped distal end portion 35
also protects the outflow aperture 11 from being blocked if the
catheter 1 comes into contact with the vessel wall. Still referring
to FIG. 3A, the catheter shaft 7 may be oriented such that it abuts
the vessel wall at distal tip 8 rather than at apex 31. In this
orientation, the distal tip 8 with guidewire exit aperture 39
contacts with the vessel wall and provides a spacing function
similar to the guard 29 to protect the outflow aperture 11 from
contacting and being blocked by the vessel wall. The forward-facing
angle of the sloped distal end portion 35 is oriented away from the
vessel wall and will not become occluded by the vessel wall because
it is protected by the distal tip 8.
[0077] FIG. 4A illustrates yet another embodiment of catheter shaft
7 of the present invention. The substantially bent distal portion 5
of the catheter 1 of this embodiment defines an angle of greater
than about 90 degrees from the axis of the catheter 1, such that
the distal tip 8 is greater in height than the proximal most edge
of the inflow lumen aperture 21. The advantages described above in
relation to the embodiment of the distal portion 5 of the catheter
1 illustrated in FIGS. 3A and 3B also apply to the embodiment
illustrated in FIGS. 4A and 4B. The embodiment illustrated in FIG.
4 has an additional clinical advantage of a more direct blood flow
path through lumen 9 which may enhance flow rates during
dialysis.
[0078] A method of inserting the catheter 1 of the present
invention into a blood vessel is also disclosed herein and
illustrated in FIGS. 5A and 5B. Although FIGS. 5A and 5B illustrate
use of the catheter 1 embodied in FIGS. 3A and 3B, the method of
inserting the catheter 1 may encompass the use of any of the
embodiments of the catheter 1 described herein and illustrated in
FIGS. 1 through 7. The method involves providing the catheter 1
described in any of FIGS. 1 through 7, inserting a guidewire 61
into a vessel 57 in a patient body; inserting the proximal end of
the guidewire 61 into the guidewire exit aperture 39 of the
guidewire lumen 37; advancing the guidewire 61 through the
guidewire lumen 37 and into the outflow lumen 9; inserting the
catheter 1 into a vessel 57 in a patient body over the guidewire
61; positioning the distal portion of the catheter at a desired
location within the target vessel 57; and removing the guidewire 61
from the catheter. If the catheter 1 of the embodiments illustrated
in any of FIG. 3 or 4 is used, the method may further involve
providing a catheter with a substantially curved or bent distal
portion 5. The method may further involve straightening the distal
portion of the catheter upon insertion of the guidewire 61 into the
guidewire lumen 37. After the guidewire 61 is inserted into the
guidewire lumen 37, the entire inserted guidewire 61 and the distal
portion of the catheter become approximately parallel with the axis
of the catheter shaft 7, as illustrated in FIG. 5A.
[0079] FIG. 5A illustrates the tapered profile of sloped distal end
portion 35 with its leading distal tip 8. This profile provides an
atraumatic dilating function by gradually expanding the tissue
track from the approximate size of a guidewire, typically 0.035
inches, to the slightly larger diameter of the distal tip 8, to the
diameter of the catheter shaft 7 at the proximal most edge of
outflow aperture 11, which is approximately 0.160 inches, to the
maximum diameter of the catheter shaft 7 at inflow aperture 21,
which is approximately 0.203 inches. Because of the dilating
profile of the catheter 1 of the current invention, use of an
introducer sheath is not necessary.
[0080] FIG. 5B illustrates a partial sectional side view of the
catheter of FIG. 5A deployed within a vessel 57 inside of a patient
body after the guidewire 61 has been removed from the catheter
shaft 7. When the guidewire 61 is removed from the catheter shaft
7, the distal portion of the catheter 1 then resumes its
substantially curved configuration. The distal portion of the
catheter has flexibility and a shaped memory, formed during the
manufacturing process of the catheter, which allows the
substantially curved distal portion of the catheter 1 to return to
its original curved unstressed state after the guidewire 61 has
been removed. Thus, the inner angle 33 of the guard portion 29
returns to an angle equal to or greater than about 90 degrees from
the catheter shaft 7 axis.
[0081] When the catheter 1 is deployed in the vessel 57, the
catheter 1 may migrate from the center of the vessel lumen 63 and
abut up against the inner wall 59 of the vessel 57, as shown in
FIG. 5B. The guard 29 contacts the inner vessel wall 59 at apex 31.
The apex 31 of the guard portion 29 acts as a shield, preventing
the aperture 21 from being occluded by vessel wall 59. It also
provides a recirculation barrier between the inflow aperture 21 and
the outflow aperture 11.
[0082] Also shown in FIG. 5B, the guard 29 also acts to orient
outflow aperture 11 more centrally within the vessel 57 where blood
volume is highest, thereby further minimizing recirculation rates,
increasing the efficiency of the dialysis session, and reducing
vessel wall 59 trauma caused by sustained contact with the
catheter.
[0083] FIG. 6A illustrates yet another embodiment of the catheter 1
at line G-G of the present invention. In this embodiment, the
catheter 1 is identical to the embodiment illustrated in FIG. 1,
except that the catheter 1 has a guidewire lumen 27 which extends
substantially the entire length of the catheter 1 from the distal
tip 8 to bifurcate 49, where the guidewire 27 lumen fluidly joins
to extension tube 54.
[0084] FIG. 6B illustrates the cross-sectional area of the catheter
1 of FIG. 6A taken along line G-G and H-H. The cross-sectional view
along line G-G illustrates the outflow lumen 9 and the inflow lumen
19 separated by a dividing wall 17 and a guidewire lumen 27 defined
by an outer wall 43. The outer diameter of the catheter 1 is
approximately 0.203 inches, equivalent to previous embodiments. To
accommodate the guidewire lumen 27 within the double-D section of
the catheter 1 without increasing the outer diameter of the
catheter 1, the dividing wall 17 is positioned slightly off-center.
This balances the cross-sectional area of each lumen providing
consistent even flow in both directions. The resulting
cross-sectional area of each lumen 19 and 9 is approximately 0.0065
inches.sup.2, which is approximately 0.00052 inches less than the
transitional guidewire lumen embodiments previously illustrated.
This luminal area reduction of 0.00052 is insignificant in terms of
impact on flow rates.
[0085] Along line H-H at the distal portion 5 of the catheter 1,
the double-D lumen has transitioned to a single round outflow lumen
9. Also illustrated along line H-H, the cross-sectional lumen area
of outflow lumen 9 is maintained at its largest diameter to distal
aperture 11, as with the previous embodiments.
[0086] The embodiment illustrated in FIGS. 6A and 6B has several
clinical advantages. The guidewire lumen 27, which is fluidly
connected with extension tube 54, may be used for the delivery of
drugs, injections of fluids, such as contrast media, and for blood
sampling, eliminating the need for the practitioner to place a
secondary vascular access device. In addition, the cross-sectional
luminal areas of previous embodiments are maintained without having
to increase the outer diameter of the catheter 1. The substantially
straight shape of the catheter 1 provides for direct blood flow
paths and optimal flow rates in addition to minimal guidewire
friction in comparison to curved embodiments. The continuous
guidewire lumen 27 allows for the guidewire exchange or
re-insertion, if necessary, after the catheter 1 has been placed in
a vessel. The distal portion 5 of the catheter 1 is concentrically
aligned within the outer circumference of the proximal portion 3 of
the catheter shaft 7, as best illustrated in FIG. 6B, along line
H-H. This alignment provides a structural barrier separating the
inflow and outflow lumens 19 and 9, thereby minimizing
recirculation rates during the dialysis session.
[0087] In an alternative embodiment of the present invention, as
illustrated in FIGS. 7A and 7B, the guidewire lumen 27 may have a
liner 64 placed along the inner wall 43 of the lumen 27. The liner
64 is a tubular structure that functions to increase the burst
pressure of the guidewire lumen 27. Burst pressure is defined
herein as the amount of pressure that the lumen 27 may withstand
during high pressure applications, such as contrast media
injections, before rupturing. The liner 64 allows a higher burst
pressure of the lumen 27 by providing a liner 64 material with a
higher yield stress than the material of the catheter shaft 7. The
liner 64 may be made of any suitable material that may increase the
burst pressure of the lumen 27, such as, but not limited to nylon
or polyamide. The liner 64 may also reduce friction over the
guidewire 61, thereby further enhancing guidewire 61 tracking
capabilities of the lumen 27.
[0088] The liner 64 may have a wall thickness of between
approximately 0.002 and 0.005 inches. The liner 64 may optionally
be constructed of a higher strength material than the catheter
shaft 7, so as to allow thinner surrounding catheter wall sections
102, thereby minimizing reduction in luminal cross-sectional area
of the inflow 19 and outflow 9 lumens. The liner 64 disclosed
herein may also be placed inside of the partial guidewire lumen 37
described herein in the previous embodiments and illustrated in
FIGS. 1 through 5.
[0089] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to". Those familiar with the art may recognize
other equivalents to the specific embodiments described herein,
which equivalents are also intended to be encompassed by the
claims.
[0090] Further, the particular features presented in the dependent
claims can be combined with each other in other manners within the
scope of the invention such that the invention should be recognized
as also specifically directed to other embodiments having any other
possible combination of the features of the dependent claims. For
instance, for purposes of claim publication, any dependent claim
which follows should be taken as alternatively written in a
multiple dependent form from all prior claims which possess all
antecedents referenced in such dependent claim if such multiple
dependent format is an accepted format within the jurisdiction
(e.g., each claim depending directly from claim 1 should be
alternatively taken as depending from all previous claims). In
jurisdictions where multiple dependent claim formats are
restricted, the following dependent claims should each be also
taken as alternatively written in each singly dependent claim
format which creates a dependency from a prior
antecedent-possessing claim other than the specific claim listed in
such dependent claim below.
[0091] This completes the description of the selected embodiments
of the invention. Those skilled in the art may recognize other
equivalents to the specific embodiments described herein which
equivalents are intended to be encompassed by the claims attached
hereto.
* * * * *