US20120238964A1 - Sleeve valve catheters - Google Patents

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.

Description

RELATED APPLICATION
• This application is a continuation of U.S. patent application Ser. No. 11/754,759, filed May 29, 2007 entitled “SLEEVE VALVE CATHETERS” which is a continuation-in-part to non-provisional U.S. patent application Ser. No. 10/382,757 filed Mar. 6, 2003, U.S. Pat. No. 7,235,067, herein incorporated by reference in its entirety.
• This application is related to U.S. patent application Ser. No. 13/486,523, filed on even date herewith entitled “SLEEVE VALVE CATHETERS” herein incorporated by reference in its entirety.
TECHNICAL FIELD
• The invention relates to sleeve valve catheters for administration of material into a body of a patient.
BACKGROUND
• 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.
• 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.
• 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
• FIG. 1 is a schematic diagram illustrating a sleeve valve catheter.
• FIG. 2 is a cross-sectional side view illustrating an exemplary sleeve valve catheter that comprises a sleeve with a tapered edge.
• FIG. 3 is a cross-sectional side view of another exemplary sleeve valve catheter.
• 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.
• FIG. 5 is a cross-sectional side view illustrating another exemplary sleeve valve catheter that comprises a sleeve with a tapered edge.
• FIG. 6 is a cross-sectional end view illustrating the sleeve valve catheter ofFIG. 2.
• FIG. 7 is a cross-sectional end view of a sleeve valve catheter with a non-uniform thickness.
• FIG. 8 is a cross-sectional side view illustrating another exemplary sleeve valve catheter that comprises a plurality of sleeve valves with tapered edges.
• 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.
• 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.
• FIG. 11 is a flow diagram illustrating a method of manufacturing a sleeve of a sleeve valve catheter.
• FIG. 12 is a schematic diagram illustrating an implanted catheter including a sleeve valve according to one embodiment of the present invention.
• FIG. 13 is a schematic diagram illustrating an implanted catheter including a sleeve valve according to another embodiment of the present invention.
• FIG. 14 is a schematic diagram illustrating a distal end of the implanted catheter ofFIG. 12.
• FIG. 15 is a schematic diagram illustrating a sleeve valve catheter.
DETAILED DESCRIPTION
• FIG. 1 is a schematic diagram illustrating asleeve valve catheter10 for administration of therapeutic agents or nutrients into a body of a patient.Sleeve valve catheter10 is inserted into the body of the patient and, more particularly, into avessel12 of the patient defined byvessel walls13A and13B (“vessel walls13”).Sleeve valve catheter10 infuses fluid or other material into the blood stream flowing throughvessel12. Although in the example ofFIG. 1sleeve valve catheter10 is implanted withinvessel12,sleeve valve catheter10 may be implanted in other body lumens, cavities, or spaces, such as the brain ventricle.
• In the example ofFIG. 1,sleeve valve catheter10 includes acatheter body14 with aproximal end16 that resides outside of the body of the patient and adistal end18 that is implanted withinvessel12. In other embodiments,proximal end16 may be within the body and coupled to an implanted drug delivery device or a catheter access port.Sleeve valve catheter10 receives a fluid or other material via an opening19 atproximal end16. 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 inFIG. 1,proximal end16 includes a fitting20 that couples to a source of the fluid or to a device that injects the fluid into the body of the patient. Types of fitting20 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.
• Distal end18 ofcatheter body14 may be tapered to reduce the likelihood of thrombus formation atdistal end18. Thrombus formation generally occurs in regions of turbulence and/or stagnancy in the blood flow, which leads to clotting. In the example ofFIG. 1, the distal end ofcatheter body14 is rounded to reduce the amount of blood flow turbulence and stagnancy. However,distal end18 may be tapered differently. For instance,distal end18 may have a linear or nonlinear taper.Catheter body14 may be closed atdistal end18 in order to build up pressure withincatheter body14 to open a pressure responsive valve.
• Sleeve valve catheter10 further includes at least onesleeve valve22 that functions as a one-way pressure responsive valve. In other words,sleeve valve22 permits fluid flow fromcatheter10 tovessel12, but restricts fluid flow intocatheter10.Sleeve valve22 comprises asleeve24 that surrounds a portion ofcatheter body14 proximate anexit port26 and coversexit port26.Sleeve24 is constructed of an elastic material, which providessleeve24 the ability to expand and contract. When fluid within a lumen formed bycatheter body14 generates a large pressure differential betweeninside catheter body14 andoutside catheter body14, the fluid in the lumen attempts to exitcatheter body14 viaexit port26.
• In response to the pressure build-up withincatheter body14, sleeve24 expands. With a large enough pressure differential,sleeve24 will expand enough to allow the fluid to flow fromcatheter body14 tovessel12. In this manner,sleeve valve catheter10 administers therapeutic agents or nutrients into a body of a patient. When the fluid within the lumen ofcatheter body14 does not have a high pressure level,sleeve24 forms a seal with an exterior surface ofcatheter body14, preventing fluid from flowing into or out ofcatheter body14.
• In one embodiment,sleeve valve catheter10 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 ofcatheter body14.
• In accordance with one embodiment of the invention, as in the example illustrated inFIG. 1,catheter body14 includes a recess that receivessleeve24 such thatsleeve24 has substantially the same outer diameter ascatheter body14. In this manner, an exterior surface ofsleeve24 is substantially flush with the exterior surface ofcatheter body14, which reduces the turbulence and/or stagnancy in the blood flow adjacent the edge ofsleeve24 that may lead to thrombus formation.FIGS. 9A-B and10 further describe alternate embodiments of such sleeve valve catheters. In other embodiments, ifsleeve24 is not positioned within a recess, one or both edges ofsleeve24 are tapered to reduce the turbulence and/or stagnancy in the blood flow adjacent the edge ofsleeve24.
• In another embodiment of the present invention, an exterior portion ofsleeve valve catheter10 includes a coating that elutes a therapeutic agent. The coating may be on an exterior portion ofsleeve24, an exterior portion ofcatheter body14, 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 ofsleeve valve catheter10 includes a coating of Heparin to reduce the likelihood of thrombus formation.
• Sleeve24 is constructed of an elastic material such as silicone. The elastic material givessleeve24 the compliance to expand and contract in response to applied pressure differentials.Catheter body14 is constructed such thatsleeve24 is more compliant thancatheter body14.Sleeve24 must be more compliant thancatheter body14 in order for the applied pressure differentials to opensleeve valve22. In one embodiment according to the present invention,catheter body14 is constructed of a non-compliant polymer to preventcatheter body14 from expanding, or ‘ballooning’, which increases the liquid volume and pressure necessary to opensleeve valve22. Non-compliant polymers, from whichcatheter body14 is constructed, are selected from a group of biocompatible materials including polyurethane, fluoropolymers, polyimide, polyamide, polyethylene, and polypropylene. In another embodiment according to the presentinvention catheter body14 is constructed of a compliant material such as a silicone, wherein walls ofcatheter body14 are formed thicker thansleeve24 so thatcatheter body14 is less compliant thansleeve24. Whensleeve24 andcatheter body14 are both constructed of silicone, crosslinking between the silicone material ofsleeve24 with the silicone material ofcatheter tube14 may causesleeve24 andcatheter body14 to stick together and resist opening in response to the pressure differential. According to another embodiment of the present invention, in which bothcatheter body14 andsleeve30 are constructed of silicone, a material is applied at the interface betweensleeve24 andbody14 in order to prevent blocking between the interface ofcatheter body14 andsleeve30. The term “blocking” refers to the cross-linking between the silicone material ofsleeve30 with the silicone material ofcatheter tube14.
• Sleeve valve catheter10 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.
• FIG. 2 is a cross-sectional side view of an exemplarysleeve valve catheter28 that comprises asleeve30 with atapered edge32 to reduce the likelihood of occlusion.FIG. 2(A) illustratessleeve valve catheter28 in a closed state. The term “closed” state refers to a state in which a large enough pressure differential does not exist to opensleeve valve catheter28 to allow fluid flow from the interior lumen ofsleeve valve catheter28 to a body of a patient.FIG. 2(B) illustratessleeve valve catheter28 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 ofsleeve30 and thereby opensleeve valve catheter28, allowing the sleeve valve catheter to infuse fluid into the body of the patient.
• Sleeve valve catheter28 comprises acatheter body14 including aninterior surface34 defining alumen36 and anexterior surface38 exposed to an environment within avessel12.Sleeve valve catheter28 further includes at least oneexit port26 alongcatheter body14 through which material exitslumen34.Sleeve30 surrounds a portion ofexterior surface38 and coversexit port26. In one embodiment according to the present invention, an inner diameter ofsleeve30 is substantially equal to an outer diameter ofcatheter body14 such thatsleeve30 fits snuggly around the portion ofexterior surface38adjacent exit port26. In other embodiments, the inner diameter ofsleeve30 is slightly smaller than the outer diameter ofcatheter body14 in order to create a tighter fit. In alternate embodiments,exit port26 is circular, oval, square or any other geometric shape.Sleeve30 andexit port26 together form pressureresponsive sleeve valve29.
• Blood flow oversleeve30 occurs in the direction indicated byarrows40A and40B (“arrows40”). In the example ofFIG. 2(A),sleeve valve catheter28 is in a closed state. While in the closed state,sleeve30 forms a seal with the portion ofexterior surface38adjacent exit port26 to prevent fluid flow fromlumen36 to the body of the patient. In one embodiment, taperededge32 is proximatedistal end18 ofcatheter28. Alternatively, taperededge32 is farther fromdistal end18, or both edges ofsleeve30 are tapered to further reduce turbulence and stagnancy in the blood flow.
• In one embodiment according to the present invention,sleeve30 is molded, via Liquid Silicone Rubber (LSR) molding techniques, often referred to as Liquid Injection Molding (LIM), to form taperededge32; a material from whichsleeve30 is molded, liquid silicone rubber, or LSR, allows molding ofsleeve30 with a thickness and uniformity that is not possible with conventional silicone molding techniques. According to one embodiment, the LSR used to moldsleeve30 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 ofsleeve30, which increases the compliance and lowers the opening pressure ofsleeve30. 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.
• Further, LSR allows taperededge32 to be molded rather than cut. However, according to another embodiment of the present invention,sleeve30 is formed using other shaping techniques such as hot or cold transfer silicone molding, injection molding, extrusion, dipping or the like. For example,sleeve30 is extruded and then cut to form taperededge32.
• Tapered edge32 has a constant negative slope that gradually tapers from an outer edge ofsleeve30 toexterior surface38 ofcatheter body14. The slope of taperededge32 may be varied to achieve a more gradual taper or a steeper taper.
• In the example ofFIG. 2(B),sleeve valve catheter28 is in an open state.Sleeve valve catheter28 transforms from the closed state to the open state in response to an increased pressure level withinlumen36 that causessleeve valve29 to open. More particularly, as the pressure level of a fluid withinlumen36 increases, the fluid attempts to exitlumen36 viaexit port26. As the pressure of the fluid attempting to exitlumen36 viaexit port26 increases,sleeve30 begins to expand.Sleeve30 continues to expand, in turn, breaking the seal betweensleeve30 and the portion of theexterior surface38adjacent exit port26.
• As illustrated inFIG. 2(B), the seal betweensleeve30 andexterior surface38 breaks toward one of the edges ofsleeve30. However, seal betweensleeve30 andexterior surface38 may be broken toward both edges ofsleeve30 in other embodiments. When the pressure differential betweeninside catheter body14 andoutside catheter body14 is large enough,sleeve30 will expand enough to putlumen36 in fluid communication with the blood flow throughvessel12. The pressure differential is such thatsleeve valve catheter28 infuses nutrients or therapeutic agents into the body of the patient as shown byarrow42. Further, the large pressure differential when the valve is open generally prevents the occurrence of blood ingression intolumen36 during the open state.
• The pressure level at whichsleeve30 expands depends on the properties ofsleeve30 such as the compliance ofsleeve30, the length ofsleeve30, the thickness ofsleeve30 or any combination thereof. For example, a thickness ofsleeve30 neardistal end18 is thinner than a thickness ofsleeve30 towardproximal end16 so thatsleeve30 only opens towarddistal end18. The pressure differential at whichsleeve30 expands may further depend on the size and shape ofexit port26. For example, a larger exit port needs a smaller pressure differential to causesleeve30 to expand than a smaller exit port.
• As described above,sleeve30 is constructed of an elastic material such as silicone and must be more compliant thancatheter body14 in order forsleeve valve29 to operate properly. In the case in which bothcatheter body14 andsleeve30 are constructed of silicone, according to one embodiment of the present invention, a material, for example graphite or talc, is applied at the interface betweensleeve30 andbody14 in order to prevent blocking betweenbody14 andsleeve30. The term “blocking” refers to the crosslinking between the silicone material ofsleeve30 with the silicone material ofcatheter tube14, which can causesleeve30 andcatheter tube14 to stick together and resist opening in response to the pressure differential. Crosslinking between the interface ofcatheter body14 andsleeve30 occurs at a given time and temperature. When blocking occurs, a much higher pressure differential is needed to opensleeve valve30, which is undesirable.
• FIG. 3 is a cross-sectional side view of another exemplary sleeve valve catheter43 that allows material to exitlumen36 out both ends ofsleeve30. Sleeve valve catheter43 conforms substantially tosleeve valve catheter28 illustrated inFIG. 2(B), but the seal betweensleeve30 andexterior surface38 breaks toward both edges ofsleeve30. In this manner, material exits lumen36 via both ends ofsleeve30 as illustrated by arrows42A-42B (“arrows42”).
• FIG. 4 is a cross-sectional side view of another exemplary sleeve valve catheter44 that has a non-uniform thickness along a length ofsleeve30. Sleeve valve catheter44 conforms substantially tosleeve valve catheter28 illustrated inFIG. 2, but a thickness ofsleeve30 neardistal end18 is thinner than a thickness ofsleeve30 towardproximal end16. The varying thickness along the length ofsleeve30 causessleeve30 to be more compliant towarddistal end18. In this manner, the pressure differential necessary to opensleeve30 towarddistal end18 is decreased, in turn, causingsleeve valve29 to more likely infuse fluids towarddistal end18. In an alternate embodiment, the varying thickness along the length ofsleeve30 is in the other direction, i.e., the thickness ofsleeve30 nearproximal end16 is thinner than a thickness ofsleeve30 towarddistal end18.
• FIG. 5 is a cross-sectional side view of another exemplarysleeve valve catheter45 that comprises asleeve30 with atapered edge48 to reduce the likelihood of occlusion.Sleeve valve catheter45 conforms substantially tosleeve valve catheter28 illustrated inFIG. 2, but taperededge48 is shaped differently from taperededge32 ofFIG. 2.Tapered edge48 is a curved taper instead of a constant negative slope taper. More particularly, the curved taper of taperededge48 takes a convex shape. However, the tapered edge of the sleeve valve catheters may take any shape.
• FIG. 6 is a cross-sectional end view ofsleeve valve catheter28 ofFIG. 2 from C to C′.Sleeve valve catheter28 includes acatheter body14 that defines alumen36.Sleeve valve catheter28 further includes at least oneexit port26. Asleeve30 completely encirclescatheter body14adjacent exit port26 and coversexit port26. As shown in the example ofFIG. 6, an inner diameter ofsleeve30 is substantially the same as an outer diameter ofcatheter body14. In other embodiments, the unstretched inner diameter ofsleeve30 is slightly smaller than the outer diameter ofcatheter body14 in order to obtain a tighter fit. The tighter fit ofsleeve30 around the portion ofcatheter body14adjacent exit port26 forms a stronger seal whilesleeve valve catheter28 and, more particularly,sleeve valve29 is in a closed state. The seal reduces the likelihood of blood ingression, which may lead to occlusion. Although in the example ofFIG. 6sleeve valve catheter28 has a circular shape,sleeve valve catheter28 may be geometrically formed to take any shape.
• In the example illustrated inFIG. 6,sleeve30 has a uniform thickness, i.e., the thickness ofsleeve30 remains the same around the entire circumference ofcatheter body14. However, in an alternate embodiment,sleeve30 is formed with a non-uniform thickness around the circumference of the catheter body, as illustrated inFIG. 7. In the example illustrated inFIG. 6, the thickness ofsleeve30 is less than the thickness ofcatheter body14 in order forsleeve30 to be more compliant thancatheter body14. As mentioned above, moldingsleeve30 using LSR allowssleeve30 to be thinner and more uniform than whensleeve30 is formed via conventional molding or other shaping techniques. In addition, LSR molding permitssleeve30 to be molded with nonuniformities, if desired, such as reduced thicknesses in particular areas.
• In the example illustrated inFIG. 6,sleeve valve catheter28 includes asingle exit port26. However, in alternate embodiments,sleeve valve catheter28 includes multiple exit ports covered bysleeve30 and circumferentially displaced relative to one another around the circumference ofcatheter body14 to reduce the pressure differential needed to expandsleeve30 to opensleeve valve catheter28.
• FIG. 7 is a cross-sectional end view of a sleeve valve catheter49 with a non-uniform thickness about the circumference ofcatheter body14. Sleeve valve catheter49 conforms substantially tosleeve valve catheter28 illustrated inFIG. 6, but sleeve51 has a non-uniform thickness. Specifically, the thickness of sleeve51proximate exit port26 is less than the thickness of a major portion of sleeve51. The reduced thickness of sleeve51proximate exit port26 makes sleeve51proximate exit port26 more resilient and decreases the pressure differential needed to separate sleeve51 fromcatheter body14. In this manner, the thickness of sleeve51 may be adjusted in order to adjust the pressure differential required to expand and open sleeve51.
• FIG. 8 is a cross-sectional side view of another exemplarysleeve valve catheter50 that comprises a plurality ofsleeve valves52A-52B (“sleeve valves52”) with taperededges32A-32B (“taperededges32”) to reduce the likelihood of occlusion.
• Sleeve valve catheter50 comprises acatheter body53 that includes aninterior surface34 defining alumen36 and anexterior surface38 exposed to an environment within a vessel.Sleeve valve catheter50 further includesexit ports54A-54B (“exit ports54”) alongcatheter body53 through which material exitslumen36. Exit ports54 may be circular, oval, square or any other geometric shape.Sleeves56A-56B (“sleeves56”) surround a portion ofexterior surface38 adjacent respective exit ports54 and cover exit ports54. Althoughsleeve valve catheter50 ofFIG. 8 only includessleeve valves52A and52B,sleeve valve catheter50 may include any number of sleeve valves52.
• As illustrated inFIG. 8, exit ports54 are longitudinally displaced relative to one another along a length ofcatheter body53 andexit port54A is located farther fromdistal end16 thanexit port54B. As further illustrated inFIG. 8, exit ports54 are circumferentially displaced relative to one another along the length of catheter body54. In the example cross section ofFIG. 8,exit port54A resides on a top circumferential portion andexit port54B resides on a bottom circumferential portion ofcatheter body53. In this manner, exit ports54 reside on opposite sides ofcatheter body53. In an alternate embodiment, exit ports54 are both on a top portion ofcatheter body53. The longitudinal and circumferential displacement of exit ports54 provides redundancy in case one of exit ports54 becomes occluded.
• According to embodiments of the present invention, sleeve valves52 are constructed to allow material to exitlumen36 at different pressure levels. The pressure differential at which sleeve valves52 allow material to exitlumen36 are adjusted by selecting the size of exit ports54, the length and thickness of sleeves56, the compliance of sleeves56, the number of exit ports associated with each of sleeves56 or a combination thereof. For example,exit port54B is larger thanexit port54A in order to reduce the pressure level at which slitvalve52B will open. In this manner,sleeve valve catheter50 may be designed such thatsleeve valve52A functions as a surrogate valve forsleeve valve52B. In other words,sleeve valve52A allows material to exitlumen36 only whensleeve valve52B becomes occluded. For example,sleeve valve52B may allow material to exitlumen36 at a lower pressure differential thansleeve valve52A. Whensleeve valve52B becomes occluded, material no longer exitslumen36, in turn, causing the pressure level withinlumen36 to increase. The pressure level withinlumen36 continues to increase until the pressure level exceeds a threshold pressure differential ofsleeve valve52A. In this manner, when one of exit ports54 becomes occluded,catheter50 may remain implanted instead of being replaced.
• Although in the example illustrated inFIG. 8 tapers32 of sleeves56 are linear, the tapers of sleeves56 may be curved tapers that have a convex or concave shape. Further, the tapers of sleeves56 may be a combination of different shaped tapers.
• FIG. 9 is a cross-sectional side view of an exemplarysleeve valve catheter60 that includes asleeve64 having substantially the same outer diameter ascatheter body62 to reduce the likelihood of occlusion ofcatheter60.FIG. 9(A) illustratessleeve valve catheter60 in a closed state.FIG. 9(B) illustratessleeve valve catheter60 in an open state.
• Sleeve valve catheter60 comprises acatheter body62 that includes aninterior surface66 defining alumen68 and anexterior surface70 exposed to an environment within avessel12.Exterior surface70 includes at least one recessedarea72 to receivesleeve64.Sleeve valve catheter60 further includes at least oneexit port74 alongcatheter body62 through which material may exitlumen68. As illustrated inFIG. 9,exit port74 is formed within recessedarea72 ofcatheter body62.Sleeve64 surroundsexterior surface70 of recessedarea72adjacent exit port74 and coversexit port74.Sleeve64 andexit port74 together comprise asleeve valve76.
• According to one embodiment, an inner diameter ofsleeve64 is substantially the same as an outer diameter of recessedarea72 ofcatheter body62; in an alternate embodiment, the inner diameter ofsleeve64 is slightly smaller than the outer diameter of recessedarea72 in order to fit tightly. As illustrated inFIG. 9, the outer diameter ofsleeve64 is substantially the same as an outer diameter of a non-recessed portion ofcatheter body62. In this manner, the exterior surface ofsleeve64 is substantially flush withexterior surface70 ofcatheter body62, which reduces the likelihood of thrombus formation from turbulence and/or stagnancy in the blood flow.
• In order to formsleeve valve76, a solvent that causessleeve64 to expand may be applied tosleeve64 in order to fitsleeve64 over non-recessed portions ofcatheter body62. Aftersleeve64 is in place, the solvent begins to evaporate, in turn, causingsleeve64 to contract to the original size. Examples of solvents include isopropyl alcohol and heptane.
• In the example illustrated inFIG. 9(B),sleeve valve76 is in an open state.Sleeve valve76 transforms from the closed state to the open state in response to an increased pressure level withinlumen68. More particularly, as the pressure of a material withinlumen68 increases, the material begins to attempt to exitlumen68 viaexit port74. As the pressure of the fluid attempting to exitlumen68 viaexit port74 increases,sleeve64 begins to expand.Sleeve76 continues to expand, in turn, separatingsleeve64 fromexterior surface70 of recessedarea72. When the pressure differential betweeninside catheter body62 andoutside catheter body62 is large enough,sleeve64 separates fromexterior surface70 and puts lumen68 in fluid communication with the blood flow throughvessel12. In this manner,sleeve valve catheter60 opens to infuse nutrients or therapeutic agents into the body of the patient.
• As described above for sleeves with a tapered edge,sleeve64 is constructed of an elastic material such as silicone. According to one embodiment of the present invention,sleeve64 is molded using LSR molding techniques to achieve a thinner, more uniform sleeve than may be achieved via conventional shaping techniques.Catheter body62 is constructed such thatsleeve64 is more compliant thancatheter body62. In one embodiment according to the present invention,catheter body62 is constructed of a non-compliant polymer such as polyurethane, fluoropolymer, polyimide, polyamide, polyethylene, or polypropylene. According to an alternate embodiment,catheter body62 is constructed of silicone. In the case in which bothcatheter body62 andsleeve64 are constructed of silicone,catheter body62 may be thicker thansleeve64 so that the compliance ofsleeve64 is greater. Further, in one embodiment, a material, such as graphite or talc, is applied at an interface betweensleeve64 andbody62 in order to prevent blocking betweenbody62 andsleeve64 due to crosslinking.
• FIG. 10A is a cross-sectional side view of another exemplary sleeve valve catheter77 that includes asleeve78 having substantially the same outer diameter ascatheter body62 to reduce the likelihood of occlusion of catheter77. Sleeve valve catheter77 conforms substantially tosleeve valve catheter60 illustrated inFIG. 9, butsleeve78 has a non-uniform thickness. More specifically, a thickness ofsleeve78 neardistal end18 is thinner than a thickness ofsleeve78 towardproximal end16, providingsleeve78 with a tapered diametric profile. The varying thickness along the length ofsleeve78 causessleeve78 to be more compliant towarddistal end18. In this manner, the pressure differential necessary to opensleeve valve76 towarddistal end18 is decreased, in turn, causingsleeve valve76 to more likely infuse fluids towarddistal end18. In an alternate embodiment, the varying thickness along the length ofsleeve78 is in the other direction, i.e., the thickness ofsleeve78 nearproximal end16 is thinner than a thickness ofsleeve78 towarddistal end18.FIG. 10B is a cross-sectional side view of yet another exemplarysleeve valve catheter177. As illustrated inFIG.10B sleeve178 includes an internaltapered edge180.
• FIG. 11 is a flow diagram illustrating a method of manufacturing sleeves of sleeve valve catheters, such assleeve24 ofFIG. 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.
• 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).
• 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.
• FIG. 12 is a schematic diagram illustrating an implanted catheter including a sleeve valve according to one embodiment of the present invention. As illustrated inFIG. 12, asleeve valve catheter94 includes adistal end18 implanted within abrain96 and aproximal end16 coupled to an implantedpump98.Catheter94 further includes at least one sleeve valve, conforming to any of the embodiments described herein, neardistal end18 for delivery of therapeutic agents or nutrients frompump98 tobrain96. One embodiment ofcatheter94 is further described in conjunction withFIG. 14.
• FIG. 13 is a schematic diagram illustrating an implanted catheter including a sleeve valve according to another embodiment of the present invention. As illustrated inFIG. 13, asleeve valve catheter100 includes adistal end18 implanted within aspine102 and aproximal end16 coupled to an implantedpump98.Catheter100 further includes at least one sleeve valve, conforming to any of the embodiments described herein, neardistal end18 for delivery of therapeutic agents or nutrients frompump98 tospine102.
• FIG. 14 is a schematic diagram illustrating a distal end of the implanted catheter ofFIG. 12. As illustrated inFIG. 14,distal end18 ofsleeve valve catheter94 includesbranches106A and1068, each branch including at least one sleeve valve, conforming to any of the embodiments described herein.
EXAMPLES
• 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.
• 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.
• Pressure waveforms were recorded during bolus delivery of saline atweeks 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 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

• 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

• FIG. 15 depictsmedical device200.Medical device200 includes acoil204 reinforcedcatheter202, acatheter body14, a sleeve valve catheter228, andcatheter tip210.Catheter202 is proximal to sleeve valve catheter228.Catheter202 includes acoil204 to prevent kinking and collapse of a lumen associated withcatheter body14.
• Sleeve valve214 surroundscatheter body208. In this embodiment,sleeve valve28 includes ananti-blocking interface216 disposed betweensleeve214 andtubing208.Anti-blocking interface216 comprises graphite, talc or other suitable material. In one embodiment,anti-blocking interface216 extends the full length ofsleeve214. In another embodiment,anti-blocking interface216 covers only a portion ofsleeve214. Anadhesive bond212 is coupled tosleeve214, blockinginterface216, andtubing208.Adhesive bond212 essentially mechanically connects togethersleeve214, blockinginterface216, andtubing208. Exemplaryadhesive bond212 includes silicone medical adhesive.Catheter tip210 extends distally fromsleeve214. Catheter tip comprises a radiopaque material such as barium, tantalum, or platinum filled silicone.
• 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.

Claims (10)

1. A medical device comprising:

a catheter body having proximal and distal ends and including an interior surface defining a lumen and an exterior surface having an outer circumference;

an exit port formed within a distal portion of the catheter body to allow material to exit the lumen of the catheter body; and

a pressure responsive elastic sleeve having proximal and distal ends, located around the exterior surface and covering the exit port, expandable from a closed position to an open position; and

wherein the distal end of the sleeve valve is sealed to the catheter body around the circumference of the exterior surface of the catheter body.

2. The medical device ofclaim 1, wherein the sleeve valve is sealed to the catheter body by an adhesive.

3. The medical device ofclaim 1 comprising a coil extending along the catheter body proximal to the sleeve valve.

4. The medical device ofclaim 3 wherein the coil is fabricated of metal.

5. The medical device ofclaim 3 wherein the coil is covered by an outer sleeve.

6. A medical device comprising:

a catheter body having proximal and distal ends and including an interior surface defining a lumen and an exterior surface having an outer circumference;

an exit port formed within a distal portion of the catheter body to allow material to exit the lumen of the catheter body; and

a pressure responsive elastic sleeve having proximal and distal ends, located around the exterior surface and covering the exit port, expandable from a closed position to an open position; and a coil extending along the catheter body proximal to the sleeve valve.

7. The medical device ofclaim 6 wherein the coil is fabricated of metal.

8. The medical device ofclaim 6 wherein the coil is covered by an outer sleeve.

9. The medical device ofclaim 6 wherein the distal end of the sleeve valve is sealed to the catheter body around the circumference of the exterior surface of the catheter body.

10. The medical device ofclaim 9, wherein the sleeve valve is sealed to the catheter body by an adhesive.

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