U.S. patent application number 11/754759 was filed with the patent office on 2007-12-06 for sleeve valve catheters.
Invention is credited to Jesus W. Casas, Kenneth T. Heruth, Timothy G. Laske, Mary M. Morris, David S. Olson, Michael R. Ujhelyi.
Application Number | 20070282259 11/754759 |
Document ID | / |
Family ID | 46327966 |
Filed Date | 2007-12-06 |
United States Patent
Application |
20070282259 |
Kind Code |
A1 |
Morris; Mary M. ; et
al. |
December 6, 2007 |
SLEEVE VALVE CATHETERS
Abstract
A catheter body includes an exit port over which a pressure
responsive sleeve is formed that allows material to exit a lumen of
the catheter body at a given pressure. In one embodiment, a surface
of the sleeve is approximately flush with a surface of the catheter
body.
Inventors: |
Morris; Mary M.; (Shoreview,
MN) ; Laske; Timothy G.; (Shoreview, MN) ;
Heruth; Kenneth T.; (Edina, MN) ; Ujhelyi; Michael
R.; (Maple Grove, MN) ; Casas; Jesus W.;
(Brooklyn Park, MN) ; Olson; David S.; (Scandia,
MN) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MINNEAPOLIS
MN
55432-9924
US
|
Family ID: |
46327966 |
Appl. No.: |
11/754759 |
Filed: |
May 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10382757 |
Mar 6, 2003 |
7235067 |
|
|
11754759 |
May 29, 2007 |
|
|
|
Current U.S.
Class: |
604/118 |
Current CPC
Class: |
A61M 25/0075
20130101 |
Class at
Publication: |
604/118 |
International
Class: |
A61M 25/14 20060101
A61M025/14 |
Claims
1. A medical device comprising: a catheter body including an
interior surface defining a lumen and an exterior surface; an exit
port formed within the catheter body to allow material to exit the
lumen of the catheter body; a pressure responsive sleeve fitting
around the exterior surface and covering the exit port, an outer
surface of the sleeve is substantially flush with the first outer
diameter of the catheter body; and an anti-blocking interface
between the sleeve and the catheter body.
2. The medical device of claim 1, wherein the sleeve has a
substantially uniform thickness.
3. The medical device of claim 1, wherein the anti-blocking
interface comprises one of graphite and talc.
4. The medical device of claim 1, wherein the sleeve includes a
substantially straight edge.
5. The medical device of claim 4, wherein the sleeve has a length
that ranges from about 0.1 to about 0.9 inches.
6. The medical device of claim 4, wherein the blocking interface
extends from about an entire length of sleeve to about half the
sleeve length.
7. The medical device of claim 1, wherein the sleeve includes a
plurality of sleeves and the exit port includes a plurality of exit
ports.
8. The medical device of claim 7, wherein each of the plurality of
sleeves is constructed to allow material to exit the lumen of the
catheter body at a different pressure level.
9. The medical device of claim 8, wherein one of the plurality of
sleeves, located more proximate to a distal end of the catheter
body, is constructed to allow the material to exit the lumen at a
lower pressure differential than one of the sleeves located farther
from the distal end.
10. The medical device of claim 7, wherein each of the plurality of
exit ports is a different size to allow material to exit the lumen
of the catheter body at different pressure levels.
11. The medical device of claim 7, wherein the catheter body
further comprises a first and second branch and a first of the
plurality of exit ports is formed in the first branch and a second
of the plurality of exit ports is formed in the second branch.
12. The medical device of claim 7, wherein the lumen comprises a
plurality of lumens and a first exit port corresponds with a first
of the plurality of lumens and a second exit port corresponds with
a second of the plurality of lumens.
13. A medical device comprising: a catheter body including an
interior surface defining a lumen and an exterior surface; an exit
port formed in the catheter body to allow material to exit the
lumen of the catheter body; a pressure responsive sleeve formed
from molded liquid silicone rubber having a wall thickness between
approximately 0.002 inch and approximately 0.010 inch wherein the
sleeve surrounds a portion of the exterior surface of the catheter
body and covers the exit port; and an anti-blocking interface
between the sleeve and the catheter body.
14. The medical device of claim 13, wherein the liquid silicone
rubber has a durometer between approximately 30 and approximately
70 on a shore A scale.
15. The medical device of claim 13, wherein the sleeve has a
uniform thickness.
16. The medical device of claim 13, wherein the sleeve includes a
plurality of sleeves and the exit port includes a plurality of exit
ports covered by the plurality of sleeves.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part to
non-provisional U.S. patent application Ser. No. 10/382,757 filed
Mar. 6, 2003.
TECHNICAL FIELD
[0002] The invention relates to sleeve valve catheters for
administration of material into a body of a patient.
BACKGROUND
[0003] Medical catheters are used for the administration of
therapeutic agents or nutrients either into a blood stream or a
body cavity of a patient. A catheter includes an exit port to
deliver solutions, for example nutrients or therapeutic agents, or
a combination thereof, from a lumen of the catheter to the
body.
[0004] Conventional catheters include at least one pressure
responsive valve, such as a sleeve valve. A sleeve valve is formed
by covering an exit port of the catheter with a sleeve. The sleeve
is constructed of an elastic material to provide the sleeve with
the ability to expand and contract in response to pressure
gradients. The pressure responsive valve opens and, in turn,
permits fluid flow through the catheter in response to an applied
pressure differential. More particularly, when the pressure
differential exceeds a threshold, the fluid in the lumen of the
catheter expands the sleeve and flows out of the catheter. When the
pressure differential decreases below the threshold pressure
differential, the sleeve forms a seal with the exterior of the
catheter to prevent fluid flow in or out of the catheter.
[0005] Some patients may require an implanted catheter for an
extended period of time. However, catheters that remain implanted
in a body of a patient may become occluded over time due to blood
ingression, thrombus formation or fibrous tissue encapsulation.
When a catheter does become occluded, the patient will not receive
the necessary therapeutic agents or nutrients. In this case, the
catheter must be removed and either cleaned or replaced with a new
catheter.
BRIEF DESCRIPTION OF DRAWINGS
[0006] FIG. 1 is a schematic diagram illustrating a sleeve valve
catheter.
[0007] FIG. 2 is a cross-sectional side view illustrating an
exemplary sleeve valve catheter that comprises a sleeve with a
tapered edge.
[0008] FIG. 3 is a cross-sectional side view of another exemplary
sleeve valve catheter.
[0009] FIG. 4 is a cross-sectional side view of another exemplary
sleeve valve catheter that has a non-uniform thickness along a
length of a sleeve.
[0010] FIG. 5 is a cross-sectional side view illustrating another
exemplary sleeve valve catheter that comprises a sleeve with a
tapered edge.
[0011] FIG. 6 is a cross-sectional end view illustrating the sleeve
valve catheter of FIG. 2.
[0012] FIG. 7 is a cross-sectional end view of a sleeve valve
catheter with a non-uniform thickness.
[0013] FIG. 8 is a cross-sectional side view illustrating another
exemplary sleeve valve catheter that comprises a plurality of
sleeve valves with tapered edges.
[0014] FIG. 9 is a cross-sectional side view illustrating an
exemplary sleeve valve catheter that includes a sleeve having
substantially the same outer diameter as a catheter body that the
sleeve surrounds.
[0015] FIGS. 10A and 10B are cross-sectional side views of other
exemplary sleeve valve catheters that include a sleeve having
substantially the same outer diameter as catheter body.
[0016] FIG. 11 is a flow diagram illustrating a method of
manufacturing a sleeve of a sleeve valve catheter.
[0017] FIG. 12 is a schematic diagram illustrating an implanted
catheter including a sleeve valve according to one embodiment of
the present invention.
[0018] FIG. 13 is a schematic diagram illustrating an implanted
catheter including a sleeve valve according to another embodiment
of the present invention.
[0019] FIG. 14 is a schematic diagram illustrating a distal end of
the implanted catheter of FIG. 12.
[0020] FIG. 15 is a schematic diagram illustrating a sleeve valve
catheter.
DETAILED DESCRIPTION
[0021] FIG. 1 is a schematic diagram illustrating a sleeve valve
catheter 10 for administration of therapeutic agents or nutrients
into a body of a patient. Sleeve valve catheter 10 is inserted into
the body of the patient and, more particularly, into a vessel 12 of
the patient defined by vessel walls 13A and 13B ("vessel walls
13"). Sleeve valve catheter 10 infuses fluid or other material into
the blood stream flowing through vessel 12. Although in the example
of FIG. 1 sleeve valve catheter 10 is implanted within vessel 12,
sleeve valve catheter 10 may be implanted in other body lumens,
cavities, or spaces, such as the brain ventricle.
[0022] In the example of FIG. 1, sleeve valve catheter 10 includes
a catheter body 14 with a proximal end 16 that resides outside of
the body of the patient and a distal end 18 that is implanted
within vessel 12. In other embodiments, proximal end 16 may be
within the body and coupled to an implanted drug delivery device or
a catheter access port. Sleeve valve catheter 10 receives a fluid
or other material via an opening 19 at proximal end 16. The fluid,
for example, may be a solution that includes therapeutic agents,
nutrients, or a combination thereof to be delivered to the body of
the patient. Therapeutic agents include, for example, drugs, cells,
proteins, and genetic material. As illustrated in FIG. 1, proximal
end 16 includes a fitting 20 that couples to a source of the fluid
or to a device that injects the fluid into the body of the patient.
Types of fitting 20 include a quick-connect fitting and a luer lock
fitting, and types of material sources include a syringe, a pump,
and other similar injection devices.
[0023] Distal end 18 of catheter body 14 may be tapered to reduce
the likelihood of thrombus formation at distal end 18. Thrombus
formation generally occurs in regions of turbulence and/or
stagnancy in the blood flow, which leads to clotting. In the
example of FIG. 1, the distal end of catheter body 14 is rounded to
reduce the amount of blood flow turbulence and stagnancy. However,
distal end 18 may be tapered differently. For instance, distal end
18 may have a linear or nonlinear taper. Catheter body 14 may be
closed at distal end 18 in order to build up pressure within
catheter body 14 to open a pressure responsive valve.
[0024] Sleeve valve catheter 10 further includes at least one
sleeve valve 22 that functions as a one-way pressure responsive
valve. In other words, sleeve valve 22 permits fluid flow from
catheter 10 to vessel 12, but restricts fluid flow into catheter
10. Sleeve valve 22 comprises a sleeve 24 that surrounds a portion
of catheter body 14 proximate an exit port 26 and covers exit port
26. Sleeve 24 is constructed of an elastic material, which provides
sleeve 24 the ability to expand and contract. When fluid within a
lumen formed by catheter body 14 generates a large pressure
differential between inside catheter body 14 and outside catheter
body 14, the fluid in the lumen attempts to exit catheter body 14
via exit port 26.
[0025] In response to the pressure build-up within catheter body
14, sleeve 24 expands. With a large enough pressure differential,
sleeve 24 will expand enough to allow the fluid to flow from
catheter body 14 to vessel 12. In this manner, sleeve valve
catheter 10 administers therapeutic agents or nutrients into a body
of a patient. When the fluid within the lumen of catheter body 14
does not have a high pressure level, sleeve 24 forms a seal with an
exterior surface of catheter body 14, preventing fluid from flowing
into or out of catheter body 14.
[0026] In one embodiment, sleeve valve catheter 10 includes a
plurality of sleeve valves. One or more sleeve valves act as
surrogate valves in the case a primary valve becomes occluded. The
plurality of sleeve valves may be longitudinally displaced relative
to one another along a length of catheter body 14.
[0027] In accordance with one embodiment of the invention, as in
the example illustrated in FIG. 1, catheter body 14 includes a
recess that receives sleeve 24 such that sleeve 24 has
substantially the same outer diameter as catheter body 14. In this
manner, an exterior surface of sleeve 24 is substantially flush
with the exterior surface of catheter body 14, which reduces the
turbulence and/or stagnancy in the blood flow adjacent the edge of
sleeve 24 that may lead to thrombus formation. FIGS. 9A-B and 10
further describe alternate embodiments of such sleeve valve
catheters. In other embodiments, if sleeve 24 is not positioned
within a recess, one or both edges of sleeve 24 are tapered to
reduce the turbulence and/or stagnancy in the blood flow adjacent
the edge of sleeve 24.
[0028] In another embodiment of the present invention, an exterior
portion of sleeve valve catheter 10 includes a coating that elutes
a therapeutic agent. The coating may be on an exterior portion of
sleeve 24, an exterior portion of catheter body 14, or both.
According to various embodiments, agents eluted from the coating
are selected from a group including drugs, proteins, and genes
adapted to reduce the likelihood of thrombus formation or fibrous
tissue encapsulation. For example, the exterior portion of sleeve
valve catheter 10 includes a coating of Heparin to reduce the
likelihood of thrombus formation.
[0029] Sleeve 24 is constructed of an elastic material such as
silicone. The elastic material gives sleeve 24 the compliance to
expand and contract in response to applied pressure differentials.
Catheter body 14 is constructed such that sleeve 24 is more
compliant than catheter body 14. Sleeve 24 must be more compliant
than catheter body 14 in order for the applied pressure
differentials to open sleeve valve 22. In one embodiment according
to the present invention, catheter body 14 is constructed of a
non-compliant polymer to prevent catheter body 14 from expanding,
or `ballooning`, which increases the liquid volume and pressure
necessary to open sleeve valve 22. Non-compliant polymers, from
which catheter body 14 is constructed, are selected from a group of
biocompatible materials including polyurethane, fluoropolymers,
polyimide, polyamide, polyethylene, and polypropylene. In another
embodiment according to the present invention catheter body 14 is
constructed of a compliant material such as a silicone, wherein
walls of catheter body 14 are formed thicker than sleeve 24 so that
catheter body 14 is less compliant than sleeve 24. When sleeve 24
and catheter body 14 are both constructed of silicone, crosslinking
between the silicone material of sleeve 24 with the silicone
material of catheter tube 14 may cause sleeve 24 and catheter body
14 to stick together and resist opening in response to the pressure
differential. According to another embodiment of the present
invention, in which both catheter body 14 and sleeve 30 are
constructed of silicone, a material is applied at the interface
between sleeve 24 and body 14 in order to prevent blocking between
the interface of catheter body 14 and sleeve 30. The term
"blocking" refers to the cross-linking between the silicone
material of sleeve 30 with the silicone material of catheter tube
14.
[0030] Sleeve valve catheter 10 performs as any of a number of
catheters for administration of therapeutic agents or nutrients
into a body of a patient, for example, a central venous catheter, a
vascular catheter, an intra-cerebral ventricular catheter, a
pericardial catheter, an intrathecal catheter, or an epidural
catheter. The different catheters may vary in size and shape
depending on the application; for example, a catheter that is
placed in a smaller vessel needs to have a smaller diameter than a
catheter that is placed in a larger vessel.
[0031] FIG. 2 is a cross-sectional side view of an exemplary sleeve
valve catheter 28 that comprises a sleeve 30 with a tapered edge 32
to reduce the likelihood of occlusion. FIG. 2(A) illustrates sleeve
valve catheter 28 in a closed state. The term "closed" state refers
to a state in which a large enough pressure differential does not
exist to open sleeve valve catheter 28 to allow fluid flow from the
interior lumen of sleeve valve catheter 28 to a body of a patient.
FIG. 2(B) illustrates sleeve valve catheter 28 in an open state.
The term "open" state refers to a state in which a large enough
pressure differential exists to overcome the elastic force of
sleeve 30 and thereby open sleeve valve catheter 28, allowing the
sleeve valve catheter to infuse fluid into the body of the
patient.
[0032] Sleeve valve catheter 28 comprises a catheter body 14
including an interior surface 34 defining a lumen 36 and an
exterior surface 38 exposed to an environment within a vessel 12.
Sleeve valve catheter 28 further includes at least one exit port 26
along catheter body 14 through which material exits lumen 34.
Sleeve 30 surrounds a portion of exterior surface 38 and covers
exit port 26. In one embodiment according to the present invention,
an inner diameter of sleeve 30 is substantially equal to an outer
diameter of catheter body 14 such that sleeve 30 fits snuggly
around the portion of exterior surface 38 adjacent exit port 26. In
other embodiments, the inner diameter of sleeve 30 is slightly
smaller than the outer diameter of catheter body 14 in order to
create a tighter fit. In alternate embodiments, exit port 26 is
circular, oval, square or any other geometric shape. Sleeve 30 and
exit port 26 together form pressure responsive sleeve valve 29.
[0033] Blood flow over sleeve 30 occurs in the direction indicated
by arrows 40A and 40B ("arrows 40"). In the example of FIG. 2(A),
sleeve valve catheter 28 is in a closed state. While in the closed
state, sleeve 30 forms a seal with the portion of exterior surface
38 adjacent exit port 26 to prevent fluid flow from lumen 36 to the
body of the patient. In one embodiment, tapered edge 32 is
proximate distal end 18 of catheter 28. Alternatively, tapered edge
32 is farther from distal end 18, or both edges of sleeve 30 are
tapered to further reduce turbulence and stagnancy in the blood
flow.
[0034] In one embodiment according to the present invention, sleeve
30 is molded, via Liquid Silicone Rubber (LSR) molding techniques,
often referred to as Liquid Injection Molding (LIM), to form
tapered edge 32; a material from which sleeve 30 is molded, liquid
silicone rubber, or LSR, allows molding of sleeve 30 with a
thickness and uniformity that is not possible with conventional
silicone molding techniques. According to one embodiment, the LSR
used to mold sleeve 30 is selected to have a lower viscosity than
the conventionally used high consistency rubber (HCR) silicone,
also known as gum stock silicone. The lower viscosity of the LSR
improves flowability and helps to achieve a reduced thickness of
sleeve 30, which increases the compliance and lowers the opening
pressure of sleeve 30. Conventional molding techniques, such as hot
silicone molding, for example, achieve a sleeve thickness of
approximately 0.010 inches. Using LSR, however, the sleeve
thickness may be reduced to nearly 0.0025 inches. LSR molding may
be performed using standard thermo-set injection molding machines
that have an LSR conversion kit installed. These molding machines
may be obtained from vendors such as Boy, Engel, or Arburg.
[0035] Further, LSR allows tapered edge 32 to be molded rather than
cut. However, according to another embodiment of the present
invention, sleeve 30 is formed using other shaping techniques such
as hot or cold transfer silicone molding, injection molding,
extrusion, dipping or the like. For example, sleeve 30 is extruded
and then cut to form tapered edge 32.
[0036] Tapered edge 32 has a constant negative slope that gradually
tapers from an outer edge of sleeve 30 to exterior surface 38 of
catheter body 14. The slope of tapered edge 32 may be varied to
achieve a more gradual taper or a steeper taper.
[0037] In the example of FIG. 2(B), sleeve valve catheter 28 is in
an open state. Sleeve valve catheter 28 transforms from the closed
state to the open state in response to an increased pressure level
within lumen 36 that causes sleeve valve 29 to open. More
particularly, as the pressure level of a fluid within lumen 36
increases, the fluid attempts to exit lumen 36 via exit port 26. As
the pressure of the fluid attempting to exit lumen 36 via exit port
26 increases, sleeve 30 begins to expand. Sleeve 30 continues to
expand, in turn, breaking the seal between sleeve 30 and the
portion of the exterior surface 38 adjacent exit port 26.
[0038] As illustrated in FIG. 2(B), the seal between sleeve 30 and
exterior surface 38 breaks toward one of the edges of sleeve 30.
However, seal between sleeve 30 and exterior surface 38 may be
broken toward both edges of sleeve 30 in other embodiments. When
the pressure differential between inside catheter body 14 and
outside catheter body 14 is large enough, sleeve 30 will expand
enough to put lumen 36 in fluid communication with the blood flow
through vessel 12. The pressure differential is such that sleeve
valve catheter 28 infuses nutrients or therapeutic agents into the
body of the patient as shown by arrow 42. Further, the large
pressure differential when the valve is open generally prevents the
occurrence of blood ingression into lumen 36 during the open
state.
[0039] The pressure level at which sleeve 30 expands depends on the
properties of sleeve 30 such as the compliance of sleeve 30, the
length of sleeve 30, the thickness of sleeve 30 or any combination
thereof. For example, a thickness of sleeve 30 near distal end 18
is thinner than a thickness of sleeve 30 toward proximal end 16 so
that sleeve 30 only opens toward distal end 18. The pressure
differential at which sleeve 30 expands may further depend on the
size and shape of exit port 26. For example, a larger exit port
needs a smaller pressure differential to cause sleeve 30 to expand
than a smaller exit port.
[0040] As described above, sleeve 30 is constructed of an elastic
material such as silicone and must be more compliant than catheter
body 14 in order for sleeve valve 29 to operate properly. In the
case in which both catheter body 14 and sleeve 30 are constructed
of silicone, according to one embodiment of the present invention,
a material, for example graphite or talc, is applied at the
interface between sleeve 30 and body 14 in order to prevent
blocking between body 14 and sleeve 30. The term "blocking" refers
to the crosslinking between the silicone material of sleeve 30 with
the silicone material of catheter tube 14, which can cause sleeve
30 and catheter tube 14 to stick together and resist opening in
response to the pressure differential. Crosslinking between the
interface of catheter body 14 and sleeve 30 occurs at a given time
and temperature. When blocking occurs, a much higher pressure
differential is needed to open sleeve valve 30, which is
undesirable.
[0041] FIG. 3 is a cross-sectional side view of another exemplary
sleeve valve catheter 43 that allows material to exit lumen 36 out
both ends of sleeve 30. Sleeve valve catheter 43 conforms
substantially to sleeve valve catheter 28 illustrated in FIG. 2(B),
but the seal between sleeve 30 and exterior surface 38 breaks
toward both edges of sleeve 30. In this manner, material exits
lumen 36 via both ends of sleeve 30 as illustrated by arrows
42A-42B ("arrows 42").
[0042] FIG. 4 is a cross-sectional side view of another exemplary
sleeve valve catheter 44 that has a non-uniform thickness along a
length of sleeve 30. Sleeve valve catheter 44 conforms
substantially to sleeve valve catheter 28 illustrated in FIG. 2,
but a thickness of sleeve 30 near distal end 18 is thinner than a
thickness of sleeve 30 toward proximal end 16. The varying
thickness along the length of sleeve 30 causes sleeve 30 to be more
compliant toward distal end 18. In this manner, the pressure
differential necessary to open sleeve 30 toward distal end 18 is
decreased, in turn, causing sleeve valve 29 to more likely infuse
fluids toward distal end 18. In an alternate embodiment, the
varying thickness along the length of sleeve 30 is in the other
direction, i.e., the thickness of sleeve 30 near proximal end 16 is
thinner than a thickness of sleeve 30 toward distal end 18.
[0043] FIG. 5 is a cross-sectional side view of another exemplary
sleeve valve catheter 45 that comprises a sleeve 30 with a tapered
edge 48 to reduce the likelihood of occlusion. Sleeve valve
catheter 45 conforms substantially to sleeve valve catheter 28
illustrated in FIG. 2, but tapered edge 48 is shaped differently
from tapered edge 32 of FIG. 2. Tapered edge 48 is a curved taper
instead of a constant negative slope taper. More particularly, the
curved taper of tapered edge 48 takes a convex shape. However, the
tapered edge of the sleeve valve catheters may take any shape.
[0044] FIG. 6 is a cross-sectional end view of sleeve valve
catheter 28 of FIG. 2 from C to C'. Sleeve valve catheter 28
includes a catheter body 14 that defines a lumen 36. Sleeve valve
catheter 28 further includes at least one exit port 26. A sleeve 30
completely encircles catheter body 14 adjacent exit port 26 and
covers exit port 26. As shown in the example of FIG. 6, an inner
diameter of sleeve 30 is substantially the same as an outer
diameter of catheter body 14. In other embodiments, the unstretched
inner diameter of sleeve 30 is slightly smaller than the outer
diameter of catheter body 14 in order to obtain a tighter fit. The
tighter fit of sleeve 30 around the portion of catheter body 14
adjacent exit port 26 forms a stronger seal while sleeve valve
catheter 28 and, more particularly, sleeve valve 29 is in a closed
state. The seal reduces the likelihood of blood ingression, which
may lead to occlusion. Although in the example of FIG. 6 sleeve
valve catheter 28 has a circular shape, sleeve valve catheter 28
may be geometrically formed to take any shape.
[0045] In the example illustrated in FIG. 6, sleeve 30 has a
uniform thickness, i.e., the thickness of sleeve 30 remains the
same around the entire circumference of catheter body 14. However,
in an alternate embodiment, sleeve 30 is formed with a non-uniform
thickness around the circumference of the catheter body, as
illustrated in FIG. 7. In the example illustrated in FIG. 6, the
thickness of sleeve 30 is less than the thickness of catheter body
14 in order for sleeve 30 to be more compliant than catheter body
14. As mentioned above, molding sleeve 30 using LSR allows sleeve
30 to be thinner and more uniform than when sleeve 30 is formed via
conventional molding or other shaping techniques. In addition, LSR
molding permits sleeve 30 to be molded with nonuniformities, if
desired, such as reduced thicknesses in particular areas.
[0046] In the example illustrated in FIG. 6, sleeve valve catheter
28 includes a single exit port 26. However, in alternate
embodiments, sleeve valve catheter 28 includes multiple exit ports
covered by sleeve 30 and circumferentially displaced relative to
one another around the circumference of catheter body 14 to reduce
the pressure differential needed to expand sleeve 30 to open sleeve
valve catheter 28.
[0047] FIG. 7 is a cross-sectional end view of a sleeve valve
catheter 49 with a non-uniform thickness about the circumference of
catheter body 14. Sleeve valve catheter 49 conforms substantially
to sleeve valve catheter 28 illustrated in FIG. 6, but sleeve 51
has a non-uniform thickness. Specifically, the thickness of sleeve
51 proximate exit port 26 is less than the thickness of a major
portion of sleeve 51. The reduced thickness of sleeve 51 proximate
exit port 26 makes sleeve 51 proximate exit port 26 more resilient
and decreases the pressure differential needed to separate sleeve
51 from catheter body 14. In this manner, the thickness of sleeve
51 may be adjusted in order to adjust the pressure differential
required to expand and open sleeve 51.
[0048] FIG. 8 is a cross-sectional side view of another exemplary
sleeve valve catheter 50 that comprises a plurality of sleeve
valves 52A-52B ("sleeve valves 52") with tapered edges 32A-32B
("tapered edges 32") to reduce the likelihood of occlusion.
[0049] Sleeve valve catheter 50 comprises a catheter body 53 that
includes an interior surface 34 defining a lumen 36 and an exterior
surface 38 exposed to an environment within a vessel. Sleeve valve
catheter 50 further includes exit ports 54A-54B ("exit ports 54")
along catheter body 53 through which material exits lumen 36. Exit
ports 54 may be circular, oval, square or any other geometric
shape. Sleeves 56A-56B ("sleeves 56") surround a portion of
exterior surface 38 adjacent respective exit ports 54 and cover
exit ports 54. Although sleeve valve catheter 50 of FIG. 8 only
includes sleeve valves 52A and 52B, sleeve valve catheter 50 may
include any number of sleeve valves 52.
[0050] As illustrated in FIG. 8, exit ports 54 are longitudinally
displaced relative to one another along a length of catheter body
53 and exit port 54A is located farther from distal end 16 than
exit port 54B. As further illustrated in FIG. 8, exit ports 54 are
circumferentially displaced relative to one another along the
length of catheter body 54. In the example cross section of FIG. 8,
exit port 54A resides on a top circumferential portion and exit
port 54B resides on a bottom circumferential portion of catheter
body 53. In this manner, exit ports 54 reside on opposite sides of
catheter body 53. In an alternate embodiment, exit ports 54 are
both on a top portion of catheter body 53. The longitudinal and
circumferential displacement of exit ports 54 provides redundancy
in case one of exit ports 54 becomes occluded.
[0051] According to embodiments of the present invention, sleeve
valves 52 are constructed to allow material to exit lumen 36 at
different pressure levels. The pressure differential at which
sleeve valves 52 allow material to exit lumen 36 are adjusted by
selecting the size of exit ports 54, the length and thickness of
sleeves 56, the compliance of sleeves 56, the number of exit ports
associated with each of sleeves 56 or a combination thereof. For
example, exit port 54B is larger than exit port 54A in order to
reduce the pressure level at which slit valve 52B will open. In
this manner, sleeve valve catheter 50 may be designed such that
sleeve valve 52A functions as a surrogate valve for sleeve valve
52B. In other words, sleeve valve 52A allows material to exit lumen
36 only when sleeve valve 52B becomes occluded. For example, sleeve
valve 52B may allow material to exit lumen 36 at a lower pressure
differential than sleeve valve 52A. When sleeve valve 52B becomes
occluded, material no longer exits lumen 36, in turn, causing the
pressure level within lumen 36 to increase. The pressure level
within lumen 36 continues to increase until the pressure level
exceeds a threshold pressure differential of sleeve valve 52A. In
this manner, when one of exit ports 54 becomes occluded, catheter
50 may remain implanted instead of being replaced.
[0052] Although in the example illustrated in FIG. 8 tapers 32 of
sleeves 56 are linear, the tapers of sleeves 56 may be curved
tapers that have a convex or concave shape. Further, the tapers of
sleeves 56 may be a combination of different shaped tapers.
[0053] FIG. 9 is a cross-sectional side view of an exemplary sleeve
valve catheter 60 that includes a sleeve 64 having substantially
the same outer diameter as catheter body 62 to reduce the
likelihood of occlusion of catheter 60. FIG. 9(A) illustrates
sleeve valve catheter 60 in a closed state. FIG. 9(B) illustrates
sleeve valve catheter 60 in an open state.
[0054] Sleeve valve catheter 60 comprises a catheter body 62 that
includes an interior surface 66 defining a lumen 68 and an exterior
surface 70 exposed to an environment within a vessel 12. Exterior
surface 70 includes at least one recessed area 72 to receive sleeve
64. Sleeve valve catheter 60 further includes at least one exit
port 74 along catheter body 62 through which material may exit
lumen 68. As illustrated in FIG. 9, exit port 74 is formed within
recessed area 72 of catheter body 62. Sleeve 64 surrounds exterior
surface 70 of recessed area 72 adjacent exit port 74 and covers
exit port 74. Sleeve 64 and exit port 74 together comprise a sleeve
valve 76.
[0055] According to one embodiment, an inner diameter of sleeve 64
is substantially the same as an outer diameter of recessed area 72
of catheter body 62; in an alternate embodiment, the inner diameter
of sleeve 64 is slightly smaller than the outer diameter of
recessed area 72 in order to fit tightly. As illustrated in FIG. 9,
the outer diameter of sleeve 64 is substantially the same as an
outer diameter of a non-recessed portion of catheter body 62. In
this manner, the exterior surface of sleeve 64 is substantially
flush with exterior surface 70 of catheter body 62, which reduces
the likelihood of thrombus formation from turbulence and/or
stagnancy in the blood flow.
[0056] In order to form sleeve valve 76, a solvent that causes
sleeve 64 to expand may be applied to sleeve 64 in order to fit
sleeve 64 over non-recessed portions of catheter body 62. After
sleeve 64 is in place, the solvent begins to evaporate, in turn,
causing sleeve 64 to contract to the original size. Examples of
solvents include isopropyl alcohol and heptane.
[0057] In the example illustrated in FIG. 9(B), sleeve valve 76 is
in an open state. Sleeve valve 76 transforms from the closed state
to the open state in response to an increased pressure level within
lumen 68. More particularly, as the pressure of a material within
lumen 68 increases, the material begins to attempt to exit lumen 68
via exit port 74. As the pressure of the fluid attempting to exit
lumen 68 via exit port 74 increases, sleeve 64 begins to expand.
Sleeve 76 continues to expand, in turn, separating sleeve 64 from
exterior surface 70 of recessed area 72. When the pressure
differential between inside catheter body 62 and outside catheter
body 62 is large enough, sleeve 64 separates from exterior surface
70 and puts lumen 68 in fluid communication with the blood flow
through vessel 12. In this manner, sleeve valve catheter 60 opens
to infuse nutrients or therapeutic agents into the body of the
patient.
[0058] As described above for sleeves with a tapered edge, sleeve
64 is constructed of an elastic material such as silicone.
According to one embodiment of the present invention, sleeve 64 is
molded using LSR molding techniques to achieve a thinner, more
uniform sleeve than may be achieved via conventional shaping
techniques. Catheter body 62 is constructed such that sleeve 64 is
more compliant than catheter body 62. In one embodiment according
to the present invention, catheter body 62 is constructed of a
non-compliant polymer such as polyurethane, fluoropolymer,
polyimide, polyamide, polyethylene, or polypropylene. According to
an alternate embodiment, catheter body 62 is constructed of
silicone. In the case in which both catheter body 62 and sleeve 64
are constructed of silicone, catheter body 62 may be thicker than
sleeve 64 so that the compliance of sleeve 64 is greater. Further,
in one embodiment, a material, such as graphite or talc, is applied
at an interface between sleeve 64 and body 62 in order to prevent
blocking between body 62 and sleeve 64 due to crosslinking.
[0059] FIG. 10A is a cross-sectional side view of another exemplary
sleeve valve catheter 77 that includes a sleeve 78 having
substantially the same outer diameter as catheter body 62 to reduce
the likelihood of occlusion of catheter 77. Sleeve valve catheter
77 conforms substantially to sleeve valve catheter 60 illustrated
in FIG. 9, but sleeve 78 has a non-uniform thickness. More
specifically, a thickness of sleeve 78 near distal end 18 is
thinner than a thickness of sleeve 78 toward proximal end 16,
providing sleeve 78 with a tapered diametric profile. The varying
thickness along the length of sleeve 78 causes sleeve 78 to be more
compliant toward distal end 18. In this manner, the pressure
differential necessary to open sleeve valve 76 toward distal end 18
is decreased, in turn, causing sleeve valve 76 to more likely
infuse fluids toward distal end 18. In an alternate embodiment, the
varying thickness along the length of sleeve 78 is in the other
direction, i.e., the thickness of sleeve 78 near proximal end 16 is
thinner than a thickness of sleeve 78 toward distal end 18. FIG.
10B is a cross-sectional side view of yet another exemplary sleeve
valve catheter 177. As illustrated in FIG. 10B sleeve 178 includes
an internal tapered edge 180.
[0060] FIG. 11 is a flow diagram illustrating a method of
manufacturing sleeves of sleeve valve catheters, such as sleeve 24
of FIG. 1. Initially, a mold having an inner cavity that is shaped
like a sleeve of a sleeve valve catheter is heated (80). The mold
may be heated while the mold is in a closed position. The mold is
shaped to form a sleeve that has a uniform thickness or the mold is
shaped to form a sleeve that has a non-uniform thickness. The mold
may also be shaped to attain a sleeve with tapered edges.
[0061] Next, LSR is injected into the heated mold and allowed to
cure (82, 84). The LSR injected into the mold has a lower viscosity
prior to curing than does conventional silicones, such as gum stock
silicone. The lower viscosity provides the LSR the ability to flow
and cure with a thickness that is much thinner than attainable via
conventional molding techniques such as hot and cold transfer
molding or injection molding. According to one embodiment of the
present invention, the LSR injected into the mold has a durometer
between approximately 30 and approximately 70 on a shore A scale.
However, the durometer value of the LSR may vary depending on the
application of the sleeve valve catheter. According to the present
invention, thicknesses of alternate embodiments of sleeves formed
from injection-molded LSR range from approximately 0.002 inch to
approximately 0.010 inch. When a taper is desired at one or more
edges of the sleeve and the mold is not shaped to form the tapered
edge, the cured LSR sleeve is cut to form the taper (86, 88,
90).
[0062] According to one embodiment of the present invention, the
sleeve, whether tapered or not, is chemically weakened to increase
the compliance of the sleeve (92). The sleeve may, for example, be
chemically weakened by adding silicone oil to decrease the amount
of silica in the LSR injected into the mold. Alternatively, a lower
durometer LSR may be used. The increased compliance of the sleeve
lowers the pressure differential needed to open the sleeve
valve.
[0063] FIG. 12 is a schematic diagram illustrating an implanted
catheter including a sleeve valve according to one embodiment of
the present invention. As illustrated in FIG. 12, a sleeve valve
catheter 94 includes a distal end 18 implanted within a brain 96
and a proximal end 16 coupled to an implanted pump 98. Catheter 94
further includes at least one sleeve valve, conforming to any of
the embodiments described herein, near distal end 18 for delivery
of therapeutic agents or nutrients from pump 98 to brain 96. One
embodiment of catheter 94 is further described in conjunction with
FIG. 14.
[0064] FIG. 13 is a schematic diagram illustrating an implanted
catheter including a sleeve valve according to another embodiment
of the present invention. As illustrated in FIG. 13, a sleeve valve
catheter 100 includes a distal end 18 implanted within a spine 102
and a proximal end 16 coupled to an implanted pump 98. Catheter 100
further includes at least one sleeve valve, conforming to any of
the embodiments described herein, near distal end 18 for delivery
of therapeutic agents or nutrients from pump 98 to spine 102.
[0065] FIG. 14 is a schematic diagram illustrating a distal end of
the implanted catheter of FIG. 12. As illustrated in FIG. 14,
distal end 18 of sleeve valve catheter 94 includes branches 106A
and 106B, each branch including at least one sleeve valve,
conforming to any of the embodiments described herein.
EXAMPLES
[0066] Sleeve valve catheter patency was evaluated for small
volume, intermittent, fluid delivery for twelve weeks in a canine
model. Results for a first sleeve valve catheter, identified herein
as #9134, and a second sleeve valve catheter, identified herein as
#9248, are presented in Table 1 and Table 2, respectively.
[0067] Catheter bodies for the two sleeve valve catheters were
fabricated from extruded NuSil Med4719 silicone tubing having a
durometer of approximately 55 on a Shore A scale, an ID of
approximately 0.040 inch, and an OD of approximately 0.080 inch.
For each catheter, a sleeve was fitted over an exit port formed in
the catheter body in proximity to a distal end of the catheter. The
sleeves, including tapered edges and having a wall thickness of
approximately 0.0025 inch, were fabricated from Dow Corning G7-4850
molded liquid silicone rubber having a durometer of approximately
50 on a Shore A scale. A graphite material, Graphite Micro #250
available from Asbury Graphite Mills Inc., was spread between an
internal surface of the sleeve and the catheter body, in proximity
to the exit port, to reduce blocking between the sleeve and the
catheter body.
[0068] Pressure waveforms were recorded during bolus delivery of
saline at weeks 0, 1, 2, 3, 5, 7, 9, and 12. Each bolus had a
volume of approximately 0.1 milliliter and was delivered at an
infusion rate of approximately 0.05 milliliter per minute. During
the fluid injection, intra-catheter pressures were recorded.
TABLE-US-00001 TABLE 1 Pressures for sleeve valve of # 9134 -
implanted at a junction of a jugular vein and a superior vena cava.
PRESSURE (mmHg) Weeks 0 1 2 3 5 7 9 12 Steady State 76 69 67 NA 61
75 75 73 Maximum 88 93 87 NA 73 80 84 78
[0069] TABLE-US-00002 TABLE 2 Pressures for sleeve valve of #9248 -
implanted at a junction of a superior vena cava and an atrium
PRESSURE (mmHg) Weeks 0 1 2 3 5 7 9 12 Steady State 62 94 77 63 65
62 67 80 Maximum 63 98 85 80 71 85 87 247
[0070] FIG. 15 depicts medical device 200. Medical device 200
includes a coil 204 reinforced catheter 202, a catheter body 14, a
sleeve valve catheter 228, and catheter tip 210. Catheter 202 is
proximal to sleeve valve catheter 228. Catheter 202 includes a coil
204 to prevent kinking and collapse of a lumen associated with
catheter body 14.
[0071] Sleeve valve 214 surrounds catheter body 208. In this
embodiment, sleeve valve 28 includes an anti-blocking interface 216
disposed between sleeve 214 and tubing 208. Anti-blocking interface
216 comprises graphite, talc or other suitable material. In one
embodiment, anti-blocking interface 216 extends the full length of
sleeve 214. In another embodiment, anti-blocking interface 216
covers only a portion of sleeve 214. An adhesive bond 212 is
coupled to sleeve 214, blocking interface 216, and tubing 208.
Adhesive bond 212 essentially mechanically connects together sleeve
214, blocking interface 216, and tubing 208. Exemplary adhesive
bond 212 includes silicone medical adhesive. Catheter tip 210
extends distally from sleeve 214. Catheter tip comprises a
radiopaque material such as barium, tantalum, or platinum filled
silicone.
[0072] Various embodiments along with examples of the invention
have been described. Various modifications may be made without
departing from the scope of the claims. The techniques of the
invention may, for example, be applied to a catheter that has a
sleeve valve and a slit valve. Further, the techniques of the
invention may be applied to a multi-lumen catheter. For example, a
first lumen within the multi-lumen catheter may be associated with
a first sleeve valve and a second lumen within the multi-lumen
catheter may be associated with a second sleeve valve. The sleeve
valves associated with the first and second lumens may correspond
only to their respective lumens such that the fluids of the lumens
do not interact with one another within the catheter. These and
other embodiments are within the scope of the following claims.
* * * * *