US20060264694A1 - Multilumen catheter for minimizing limb ischemia - Google Patents

Abstract

A multilumen catheter that maximizes the blood flow into and out of the patient's vasculature while also providing for passive and/or active perfusion of tissue downstream of where the catheter resides in the vasculature. The inventive catheter comprises a proximal end, a first distal and a second distal end with first and second lumens extending from the proximal end to each of these distal ends to provide for blood circulation within one blood vessel or between two different blood vessels. The second lumen, and any additional lumens so desired, may be positioned coaxially with or radially around the first lumen. Redirecting means is provided at a distal end of at least one of said lumens for directing blood in a direction generally opposite of the direction of flow through said lumen.

Description

RELATED APPLICATIONS
• This application is a divisional of U.S. application Ser. No. 10/078,283, filed Feb. 14, 2002, which is a continuation-in-part of U.S. application Ser. No. 09/876,281, filed Jun. 6, 2001, both of which are incorporated herein in their entireties by reference.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a multilumen catheter and, in particular, to multilumen catheters designed to prevent ischemia in patients when the catheter is positioned within the body.
• 2. Description of the Related Art
• It is often necessary to divert the flow of blood from a patient's blood vessel back to the same or a different blood vessel as part of treating a patient suffering from one or more of numerous health impairments, including cardiovascular disease, such as congestive heart failure. Although surgical cut-down procedures can achieve this, percutaneous insertion of catheters has made this procedure less invasive and therefore less traumatic to the patient. Still, insertion of a cannula into the circulatory system can cause complex, and sometimes adverse, reactions within the body.
• Some of the percutaneous procedures involve removing blood from the body and subsequently returning it to the body. For example, dialysis treatment involves first removing blood from the patient's circulatory system, treating the blood outside of the body, and then returning the blood to the patient's circulatory system to perfuse the various tissues and organs. Depending on the volume of blood flow, cannulae with large carrying capacity may be necessary. By maximizing the cross-sectional area of the cannula, the volume of blood that may be removed and/or returned to the patient's vascular system via the cannula is maximized. One approach to maximize the cross-sectional area of the cannula involves using either two single lumen catheters or a multi-lumen catheter. In a recirculation application, one lumen would function to withdraw blood and one would function to return blood to the patient. One problem with using two single lumen catheters is that it subjects the patient to multiple percutaneous insertion procedures, which complicates the procedure and increases the potential for infection and other complications. Therefore, it would be desirable to have a catheter assembly which could be inserted into the patient through a single insertion site.
• Multilumen catheters in various forms have been employed for this purpose. For example, multilumen catheters have been made with two, three or more lumens to serve various aspiration and infusion functions, including extracting and returning blood to vessels, taking blood samples for testing and providing medications to the patient's vascular system. Simple multilumen catheters have been made by providing two round catheters of equal or nearly equal length joined by a web, or thin strip. This approach is described in U.S. Pat. No. 5,776,111 to Tesio. Other multilumen catheter designs have a unitary body with at least one septum dividing the lumens which extend from a proximal to a distal end.
• While multilumen catheters require only a single puncture of the epidermis, their performance is limited in at least two ways. For one, the outer perimeter of the multilumen catheter cannot exceed the inner diameter of the vessel into which it is inserted. Furthermore, the already limited cross-sectional area must be divided into at least two lumens, one for withdrawal and one for return. Thus the carrying capacity of each lumen is further reduced. To supply the same amount of blood, the velocity and pressure of the blood in the lumens must increase over what it would be in the vessel itself. This has the potential to cause damage to the vessel as blood comes jetting out of the return lumen. Also, it may put further stress upon blood cells, even causing hemolysis. Thus, multilumen catheters must be made as large as possible to carry enough blood at satisfactory conditions.
• Where the size of a catheter approaches the interior size of a vessel, less and less blood can flow around the catheter. As a result, limited blood supply reaches tissues and organs located downstream of the catheter in the vascular system. With insufficient perfusion, the tissues downstream of the lumen insertion site suffer from ischemia and become oxygen deprived. Prolonged oxygen deprivation can lead to tissue damage, as is well known in the art. Therefore, it would be desirable to have a multilumen catheter that can maximize cross-sectional area of withdrawal and return lumens while at the same time providing for acceptable levels of blood perfusion of tissue downstream of the catheter insertion site in the vascular system. It would also be advantageous to have a multilumen catheter that can also remove blood from one peripheral vessel and return blood to a second peripheral vessel.
SUMMARY OF THE INVENTION
• Overcoming many if not all of the limitations of the prior art, the present invention comprises a multilumen catheter for directing the flow of blood to and from a patient through a single cannulation site. The catheter comprises a proximal end, a first distal end and a second distal end. The first distal end extends farther from the proximal end than the second distal end. A first lumen extends between the first distal end and the proximal end and a second lumen extends between the second distal end and the proximal end. At least one aperture, but preferably a plurality of apertures may be formed in one of the first or second lumens positioned near the proximal end so that the aperture permits active maintenance or enhancement of perfusion of blood to the patient's vasculature downstream of where the aperture resides in the vasculature when the catheter is inserted into the patient for treatment.
• In an alternative embodiment, the multilumen catheter further comprises a third lumen with distal and proximal ends configured to be positioned entirely within the patient's vascular system. This third lumen is configured to permit the passive flow of blood downstream of the catheter site to maintain or enhance perfusion.
• In another embodiment, the multilumen catheter also comprises means for redirecting at least a portion of the blood flow exiting a lumen of the catheter in a direction generally opposite of the direction of flow of blood in the catheter. In one embodiment, the redirecting means is a redirecting tip positioned at the distal end of one of the lumens. In this embodiment, the redirecting tip is configured to redirect at least a portion of the blood flow exiting the lumen in a direction generally opposite of the direction of flow.
• In one embodiment, a connector formed in the shape of a Y (“Y-connector”) is positioned at the proximal end of the multilumen catheter. One leg of the Y-connector is in fluid communication with the first lumen and the other leg of the Y-connector is in fluid communication with the second lumen.
• Preferably, in an application of the present invention, an outflow conduit of a pumping system is fluidly engaged to one lumen of the multilumen catheter and an inflow conduit of the same system is fluidly engaged to the other lumen. The inflow and outflow conduits are fluidly coupled to a pump so that, when connected to the patient, the pump circulates blood from one distal end of the multilumen catheter to the other distal end, and also through at least one aperture in one of the first or second lumens positioned near the proximal end. In one application, the multilumen catheter of the present invention is incorporated into an extracardiac pumping system for supplementing blood circulation in a patient without any component thereof being connected to the patient's heart. Such a system is described in U.S. Pat. Nos. 6,200,260 and 6,299,575, which are incorporated herein by reference. The system includes, in addition to the multilumen catheter, a pump configured to pump blood through the patient at subcardiac rates, an inflow conduit fluidly coupled to the pump to divert blood to the pump from a first blood vessel, and an outflow conduit fluidly coupled to the pump to direct blood from the pump to a second blood vessel.
• Another embodiment of the present invention is an extracardiac pumping system for supplementing blood circulation through a patient without any component thereof being connected to the patient's heart. The extracardiac system comprises a multilumen catheter that has at least two lumens therethrough. Each lumen has a distal end configured for insertion into the patient's vasculature and a proximal end. At least two of the lumens are in fluid communication with each other at their proximal end. The extracardiac pumping system also comprises a pump secured within one of the lumens and configured to pump blood through the patient at subcardiac volumetric rates. The pump has an average flow rate that, during normal operation thereof, is substantially below that of the patient's heart when healthy. The pump can be operated to pump blood from one location in the patient's vasculature to a different location in the vasculature while the proximal end of each lumen resides outside the patient's body.
• The present invention also provides a method for treating a patient using one of the multilumen catheters of the present invention. The method comprises the step of inserting the multilumen catheter described above into the patient at a single cannulation site of a first blood vessel, locating the catheter such that a first lumen may be in fluid communication with a second blood vessel and a second lumen may be in fluid communication with the first blood vessel, withdrawing blood from one of said blood vessels through one of the first or said second lumens, and delivering blood through the other of said first or second lumens so that blood is delivered upstream and downstream of the cannulation site.
BRIEF DESCRIPTION OF THE DRAWINGS
• These and other features and advantages of the invention will now be described with reference to the drawings, which are intended to illustrate and not to limit the invention.
• FIG. 1 is a schematic of one embodiment of the present invention multilumen catheter.
• FIG. 2 is a schematic of an alternative embodiment of the present invention multilumen catheter.
• FIG. 3 is a schematic of an alternative embodiment of the present invention multilumen catheter with a distal end comprising a J-tip configuration.
• FIG. 4 is a schematic of an alternative embodiment of the present invention multilumen catheter comprising a Y-connector.
• FIG. 5 is a schematic of one application of one embodiment of the multilumen catheter to a patient.
• FIG. 6 is an enlarged view of a portion of the proximal end of the embodiment shown inFIG. 1 applied to a patient.
• FIG. 7 is an enlarged view of a portion of the proximal end of the embodiment shown inFIG. 2 applied to a patient.
• FIG. 8 is a schematic of an alternative embodiment of the present invention multilumen catheter having a redirecting tip.
• FIG. 9 is a schematic of an alternative embodiment of the present invention multilumen catheter having coaxial lumens.
• FIG. 10 is a cross-sectional view of the embodiment ofFIG. 9.
• FIG. 11 is a schematic of an alternative embodiment of the present invention multilumen catheter having a second lumen and a third lumen radially housed around a first lumen.
• FIG. 12 is a cross-sectional view of the embodiment ofFIG. 11.
• FIG. 13 is a schematic of an extracardiac pumping system for supplementing blood circulation through a patient.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• Turning now to the drawings provided herein, a more detailed description of the embodiments of the present invention is provided below.
• With reference toFIG. 1, one embodiment of the present invention comprises amultilumen catheter10 designed to lessen ischemia that can occur when a large diameter catheter is inserted into a patient's blood vessel. The multilumen catheter preferably is of unitary construction and requires only one entry point into the patient's body. Themultilumen catheter10 comprises at least two lumens: afirst lumen12 and asecond lumen14. Thefirst lumen12 extends from aproximal end16 of themultilumen catheter10 to a firstdistal end18. Thesecond lumen14 extends from theproximal end16 of themultilumen catheter10 to a seconddistal end20. Thelumens12,14 of themultilumen catheter10 may be arranged one of many different ways. For example, the two lumens may be joined in a side-by-side manner, forming a “figure-8” when viewed from theproximal end16. Alternately, a single cylindrical catheter housing may contain within it two or more side-by-side lumens. A cylindrical catheter housing could be formed with a diametral septum, i.e. a wall, extending across the cylinder at a diameter. A cylindrical housing with concentrically positioned lumens is also contemplated.
• The firstdistal end18 may be formed with one or moredistal apertures22, although such apertures may also be located in the seconddistal end20. Thedistal apertures22 may be positioned close together or spaced circumferentially around the distal end. Theapertures22 serve to decrease the pressure drop across the cannula tip, thereby minimizing damage to vessel walls from jetting effects. It may also be appropriate to practice methods for directing blood flow so as to minimize damage to vessel walls from jetting effects and from the recoil effect on the catheter of blood exiting a catheter. The present invention may further comprise a taperedtip24 at the firstdistal end18, which facilitates insertion and threading of the catheter into the patient. The present invention may also further comprise a taperedtip26 at the seconddistal end20.
• One preferred embodiment of the multilumen catheter further comprises a set ofapertures28 positioned on thecatheter10 near theproximal end16. Theapertures28 are formed on at least one lumen of the catheter to provide for fluid communication between one of thelumens12, or14 of themultilumen catheter10 and the blood vessel in which it resides. Aradiopaque marker30 may be positioned at thedistal end18 of themultilumen catheter10. The multilumen catheter could further comprisemarkings32 near the proximal end of the multilumen catheter which are a known distance from one or more of the distal ends. Thesemarkings32, as well as themarker30 can be used to accurately position the catheter when applied to the patient.
• In another embodiment of the present multilumen catheter shown inFIG. 2, themultilumen catheter110 comprises athird lumen134 extending between aproximal end136 and adistal end138. Thelumen134 is positioned and sized such that when themultilumen catheter110 is applied to the patient (described below), the lumen resides entirely within the patient's body. As described above, thelumen134 may be connected to thecatheter110 in a variety of ways. The purpose of thethird lumen134 is configured to permit the passive flow of blood downstream to the catheter to enhance perfusion. The embodiment shown inFIG. 2 also may haveapertures128 disposed near theproximal end116 of themultilumen catheter110. As described above, this embodiment may further comprise a taperedtip140 at the distal end of thethird lumen134 and a taperedtip142 at the proximal end of thethird lumen134 to facilitate application of the catheter to the patient.
• In one variation of the three lumen embodiment thethird lumen134 may be made of collapsible material. In the collapsed state, thethird lumen134 would conform to at least a portion of the outside surface of themultilumen catheter110. Once applied to the patient, as described in more detail below, thelumen134 would be expanded to the deployed state shown inFIG. 2. This collapsible lumen could comprise a stone basket, or a frame similar to a stent. A stone basket is a structure that can be deployed within a patient's body and is used to capture objects. Here, the basket is used primarily to create a space between thecatheter110 and the vessel wall to permit the passive flow of blood downstream of the catheter site to enhance perfusion.
• In an alternate embodiment of themultilumen catheter210, shown inFIG. 3, the firstdistal end218 is formed in the shape of a J-tip. That is, the opening at thedistal end218 may be curved such that blood exiting thelumen212 is directed back along themultilumen catheter210. Distal aperture(s)222 may be formed at the bend of the J-tip so that blood also exits thelumen212 and flows distal of thecatheter210. The “J” shape of the multi-lumen catheter tip may be formed and/or maintained by pre-loading it with a coil or with wire reinforcement, or by using a shape-memory material to create and maintain this shape. If the catheter is inserted so that the tip is straight and the “J” shape is deployed after the catheter inserted into the patient, the catheter may comprise a tapered tip at the firstdistal end218, as described above.
• Referring toFIG. 4, yet another alternative embodiment of the presentinvention multilumen catheter310 comprises a Y-connector334 formed at the proximal end of themultilumen catheter310. As described above, the lumens are separated in any suitable way such that fluid communication is provided between thedistal end318 of thelumen312 of themultilumen catheter310 and theproximal end336 of one leg of the Y-connector334, and fluid communication is provided between thedistal end320 of thelumen314 of thecatheter310 and theproximal end338 of one leg of the Y-connector334.
• Any of the multilumen catheters described herein may be made from various materials to improve their viability in long-term treatment applications. For example, it is preferred that the biocompatibility of the catheter be improved compared to uncoated catheters to prevent adverse reactions such as compliment activation and the like. To prevent such side effects, the interior lumens of the catheters can be coated with biocompatible materials. Also known in the art are anti-bacterial coatings. Such coatings may be very useful on the outer surface of the catheter. This is especially true at or about where the catheter enters the patient's skin. At such a location, the patient is vulnerable to introduction of bacteria into the body cavity. Anti-bacterial coatings can reduce the likelihood of infection and thus improve the viability of long-term treatments.
• In one application, the multilumen catheter of the present invention may be integrated into a pumping system, such as the one described in more detail in U.S. Pat. No. 6,200,260. Referring toFIG. 5, such a system comprises themultilumen catheter10, aninflow conduit38, anoutflow conduit40 and apump42. One end of theoutflow conduit40 may be connected to the proximal end of thelumen12, while the other end is connected to the inlet of thepump42. One end of theinflow conduit38 may be connected to the proximal end of thelumen14, while the other end is connected to the outlet of thepump42. This results in a flow from the firstdistal end18 to the seconddistal end20. Of course, the flow direction may be reversed using the same multilumen catheter, resulting in a flow fromdistal end20 todistal end18. In that case, theoutflow conduit40 is connected to the proximal end oflumen14 and theinflow conduit38 is connected to the proximal end oflumen12. Referring toFIG. 5, thepresent multilumen catheter10 when incorporated into a pumping system may be applied to a patient in an arterial-arterial fashion. Where themultilumen catheter10 is inserted into thefemoral artery44 of thepatient46. Theradiopaque marker30 which may be incorporated into thedistal end18 of the multilumen catheter is used to track the insertion of the catheter so that to catheter may be positioned at a desired site within the patient's vascular system. As mentioned above,markings32 on the proximal end could also be used to locate the distal end or ends.
• In one example, thedistal end18 may be located in theaortic arch48. The pump draws blood from the patient's vascular system in the area near thedistal end18 and into thelumen12. This blood is further drawn into the lumen of theconduit40 and into thepump42. Thepump42 then expels the blood into the lumen of theoutflow conduit38. This lumen carries the blood into thelumen14 of themultilumen catheter10 and back into the patient's vascular system in the area near thedistal end20. As described in greater detail below regardingFIGS. 6 and 7, theapertures28 and/or thethird lumen134 provide blood flow to the patient's vasculature downstream of where the multilumen catheter resides in the vasculature to maintain or enhance perfusion of blood. The blood flow in the multilumen catheter may be reversed. In that case, blood is drawn from the patient throughdistal end20 and returned to the patient throughdistal end18.
• Referring toFIG. 6, themultilumen catheter10 comprises features that will maintain or increase the blood flow to downstream tissue when the catheter is inserted into the patient. Theapertures28 provide for fluid communication between at least onelumen12 or14 and the patient's blood vessel. Theapertures28, thus, provides active perfusion of the downstream tissues.
• Referring toFIG. 7, thelumen134 of the embodiment shown inFIG. 2 is located entirely within the vessel when thecatheter110 is inserted into the patient. The lumen provides a pathway for blood flow to tissue downstream of the catheter so that thecatheter110 may maintain or increase the flow of blood to downstream tissue. Thelumen134, thus, provides passive perfusion. If desired, apertures may be included in one of the other two lumens to supplement passive perfusion with active perfusion.
• Referring toFIG. 8, yet another alternative embodiment of the present invention is amultilumen catheter410 for directing the flow of blood through a patient through a single cannulation site. Thecatheter410 comprises aproximal end414, a firstdistal end418, and a second distal end422. The firstdistal end418 extends distally farther from theproximal end414 than does the second distal end422. Afirst lumen426 extends between the firstdistal end418 and theproximal end414. Asecond lumen430 extends between the second distal end422 and theproximal end414. As with other embodiments, a radiopaque marker may be provided.
• Means for redirecting the flow of blood out of the catheter is provided. For example, in the embodiment ofFIG. 8, a redirectingtip434 is positioned at the distal end of one of the lumens, in this casefirst lumen426. The redirectingtip434 is configured to redirect at least a portion of the blood flow exiting thelumen426 in a direction generally opposite of the direction of flow of blood in thelumen426. One of a variety of configurations for a redirecting tip may be employed.
• In the embodiment ofFIG. 8, the redirectingtip434 has aclosed end438 at a distal position that is generally hemispherially shaped, although it need not be, and may more particularly have a parabolic profile. Preferably, a plurality ofoutlets442 are provided in the side of thelumen426 that has the redirectingtip434. Theseoutlets442 permit blood to flow out of thelumen426 and into the vasculature of the patient. As shown, theoutlets442 comprise rectangular windows framed bystructural elements444 that connect theclosed end438 to the rest of thecatheter410. It should be recognized that the number and the shape of theoutlets442 can vary.
• The redirectingtip434 further comprises aflow redirecting surface446 that defines the proximal portion of theclosed end438 and the travel path of the redirected blood. In this embodiment, a crosssection of theflow redirecting surface446 taken through the longitudinal axis of thelumen426 reflects two parabolic curves meeting at the longitudinal axis. The three dimensional shape of the redirectingsurface446 of this embodiment is defined by rotating one of the parabolic curves about the longitudinal axis of thelumen426 in which thesurface446 is positioned. This is one geometrical shape that could be used to form the redirectingsurface446 to gradually redirect the flow of the blood exiting thelumen426. Other geometrical shapes could be used as well to define the redirecting surface.
• The J-tip configuration, discussed above is another means for redirecting blood in a direction generally opposite of the direction of flow of blood through thelumen426.
• Referring toFIGS. 9 and 10, amultilumen catheter510 for directing the flow of blood through a patient through a single cannulation site comprises a proximal end516 a first distal end518 and a seconddistal end520. The first distal end518 extends distally farther from theproximal end516 than the seconddistal end520. Afirst lumen522 extends between the first distal end518 and theproximal end516. Asecond lumen524 extends between the seconddistal end520 and theproximal end516, is positioned coaxially with thefirst lumen522, and has a diameter greater than thefirst lumen522. A radiopaque marker may be provided if desired.
• One application of thecatheter510 comprises connecting thesecond lumen524 to a patient's blood vessel, preferably via an anastomosis connection after thefirst lumen522, which is preferably of tubular configuration, is inserted through the same vessel. In this application, blood may be drawn through thesecond lumen524 and redirected into thefirst lumen522 using a circulating system such as that disclosed in U.S. Pat. No. 6,200,260. In another application, the first and second lumen may be inserted in the blood vessel in a manner that results in thesecond lumen524 extending into the vessel. In this application, if desired,apertures526 may be provided to permit a more diffuse discharge of blood into the vessel fromsecond lumen524.
• Referring toFIGS. 11 and 12, amultilumen catheter610 for directing the flow of blood through a patient through a single cannulation site comprises a proximal end616, a firstdistal end618, and a seconddistal end620. The firstdistal end618 extends distally farther from the proximal end616 than the seconddistal end620. Afirst lumen622 extends between the firstdistal end618 and the proximal end616. Asecond lumen624, and if desired athird lumen626, extend between the seconddistal end620 and the proximal end616. In one application, thethird lumen626 is in fluid communication with thesecond lumen624 at a position proximal of thecatheter610, although they need not be. Thesecond lumen624 andthird lumen626 are positioned radially around thefirst lumen622 in ahousing628 that surrounds thefirst lumen622, as shown inFIG. 12. One variation of the catheter shown inFIGS. 11 and 12 comprises a fourth lumen in thehousing628 where, if desired, the fourth lumen may be in fluid communication withsecond lumen624 and/orthird lumen626 proximal of the catheter. The fourth lumen, as well as thesecond lumen624 and thethird lumen626 can be arranged in any suitable manner within thehousing628. In one embodiment, the lumens are arranged symmetrically and radially around thefirst lumen622. Asymmetrical arrangements are also contemplated.
• With reference toFIG. 13, another embodiment of the present invention comprises anextracardiac pumping system700 for supplementing blood circulation through a patient without any component thereof being connected to the patient's heart. Theextracardiac system700 comprises amultilumen catheter704 and apump706 housed within thecatheter704.
• Themultilumen catheter704 of thesystem700 comprises afirst lumen708 with aproximal end710 and adistal end712. Thecatheter704 also comprises asecond lumen716 with aproximal end718 and adistal end720. In other embodiments, thecatheter704 can have additional lumens, as discussed above. The distal ends712,720 are configured for insertion into the patient's vasculature. The twolumens708,716 are in fluid communication with each other at their proximal ends710,718.First lumen708 is longer thansecond lumen716. In other variations, thelumens708,716 could be of the same length.
• Thepump706 is secured within one of thelumens708,716 and is configured to pump blood through the patient at subcardiac volumetric rates the benefits of which are discussed in U.S. Pat. No. 6,200,260. Thepump706 has an average flow rate that, during normal operation thereof, is substantially below that of the patient's heart when healthy. Thepump706 may be operated to pump blood from one location in the patient's vasculature to a different location in the vasculature while theproximal end710 of thefirst lumen708 and theproximal end718 of thesecond lumen716 resides outside the patient's body. If desired, theentire system700 may be implanted into a patient's blood vessel.
• If desired, at least oneaperture724 is provided in one of the lumens, in this case lumen708 and is positioned in the lumen distal from theproximal end710 so that the aperture(s)724 may reside within the patient's vasculature, close to the point of insertion. Theaperture724 can maintain or enhance perfusion of blood to the patient's vasculature downstream of where the aperture(s)724 resides in the vasculature when inserted into the patient. As discussed above, one or more of the lumens of thecatheter704 can have a taperedtip726. Also, at least one aperture may be positioned proximate a distal end of at least one of the lumens. In other embodiment, a third lumen could be provided that is configured similar to, and functions the same as, thethird lumen134 shown inFIG. 2.
• A variety of redirecting tip constructions can be employed in different embodiments of thecatheter704 of theextracardiac pumping system700, as discussed above; forexample redirecting tip730. Also, theextracardiac pumping system700 may be provided with aradiopaque marker728. As discussed above, themarker728 can be used to position thecatheter704 of theextracardiac pumping system700 when applied to a patient.
• The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiment is to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (3)

1. A system for treating a patient, comprising:

a catheter, comprising:

a catheter body having a proximal end, a first distal end, and a second distal end, said first distal end extending distally farther from the proximal end than the second distal end;

a first lumen extending between said first distal end and said proximal end;

a second lumen extending between said second distal end and said proximal end and being in fluid communication with said first lumen at the proximal end; and

a redirecting tip positioned at the distal end of the first lumen;

a pump secured within one of the lumens and configured to pump blood into the first lumen at subcardiac volumetric rates;

wherein the redirecting tip is configured to redirect substantially all of the blood from the pump in a direction generally opposite of the direction of flow in the first lumen.

2. The system ofclaim 1, wherein the redirecting tip further comprises a surface positioned at the distal end of and within the first lumen, the surface configured to redirect substantially all of the blood in a direction generally opposite of the direction of flow in the first lumen.

3. The system ofclaim 1, wherein the pump is secured within the first lumen.

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