Abstract:
An infusion catheter includes a catheter body having a proximal end, a distal end, and two or more lumens extending therethrough. The infusion catheter also includes an infusion tube having a proximal end, a distal end, and one or more ports disposed therethrough. The first lumen of the catheter body is in fluid communication with the lumen of the infusion tube. A central member has a distal end connected to the distal end of the infusion tube, a proximal end, and a proximal portion slidably received in the second lumen of the catheter body. The infusion tube is disposed relative to the central member such that axial advancement of the central member relative to the catheter body radially collapses the infusion tube over the central member and axial retraction of the central member relative to the catheter body radially expands the infusion tube about the central member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/081,681 filed Jul. 17, 2008, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to medical devices and methods. More particularly, the present disclosure relates to an infusion catheter and methods for its use in delivering substances to vasculature. 
     2. Description of the Related Art 
     Catheters are used for delivering drugs through vasculature and other body lumens for a wide variety of purposes. It is often desirable to deliver thrombolytic and other substances to the peripheral vasculature, in particular the peripheral venous vasculature, in order to lyse and help remove clots in patients suffering from deep vein thrombosis (DVT) and other conditions. A number of catheters have been proposed for this purpose. For example, the catheter illustrated in U.S. Pat. No. 5,554,114 includes a pre-shaped spiral coil at its distal end, where the coil can be reduced to a smaller diameter by axially advancing a core wire to facilitate introduction into the vasculature. Although the benefits of such a pre-shaped coil are clearly evident, since the maximum diameter of the coil is fixed, the coil may be too small to treat relatively large blood vessels and may have difficulty in adequately conforming to and delivering thrombolytic and other agents throughout the length of the vessel to be treated especially in vessels of varying diameters. Thus, it would be desirable to provide alternative and improved catheters and methods for delivering thrombolytic agents to the venous and other vasculature. 
     SUMMARY 
     An infusion catheter useful for delivering drugs to the peripheral venous and other vasculature comprises a catheter body, an infusion tube, and a central member. The catheter body has a proximal end, a distal end, and at least a first lumen and a second lumen therethrough. The infusion tube has a proximal end, a distal end, and at least one lumen therethrough, where the proximal end of the infusion tube is connected to the distal end of the catheter body. The infusion tube and catheter body are connected and aligned so that the first lumen of the catheter body is in fluid communication with the lumen of the infusion tube so that substances delivered through the first lumen of the catheter body will flow into and through the lumen of the infusion tube. The infusion tube, in turn, is adapted to deliver liquid agents through its wall, typically having a plurality of perfusion ports formed therethrough. Alternatively, the infusion tube could be porous, perforate, slitted, slotted, or otherwise provided with flow passages adapted to release therapeutic, diagnostic, and other substances through its wall into the blood vessel or other body lumen being treated. 
     The central member has a distal end and a proximal end, where the distal end of the central member is connected to the distal end of the infusion tube. The proximal portion of the central member is slidably received in the second lumen of the catheter body. In this way, the central member may be axially advanced and retracted in order to lengthen and foreshorten the infusion tube, respectively. The infusion tube may be wrapped around the central member one or more times so that, when the central member is axially extended, the infusion tube will be closely positioned about the outer surface of the central member to facilitate insertion of the infusion catheter into a body lumen. Conversely, when the central member is axially retracted in the proximal direction, the infusion tube will expand radially outwardly. Advantageously, it has been found that the infusion tube will assume a generally helical or spiral configuration against the inner wall of the blood vessel or other body lumen in which it has been radially expanded. The helical or spiral configuration helps distribute the drug being delivered to the luminal wall being treated more uniformly in the radial direction. 
     In embodiments of the present disclosure, the infusion tube has a generally straight or linear shape or configuration. That is, when left in neither tension nor compression, the infusion tube will assume a generally straight configuration. In embodiments, a straight stiffening wire is provided within the lumen of the infusion tube in order to provide column strength. Usually, the infusion tube will have a polymeric body with a certain degree of stiffness, such as a nylon polymer having a stiffness or hardness in the range from about 50 kpsi to about 800 kpsi. Providing the stiffening wire increases the column strength of the infusion tube. The real advantage, however, is that when the infusion tube is foreshortened, the stiffening wire helps provide a greater hoop strength as the infusion tube assumes its spiral or helical configuration about the central member. Typically, the stiffening wire is a stainless steel wire having a diameter in the range from about 0.08 mm to about 0.7 mm. The stiffening wire is attached at its distal end to the infusion tube at or near the distal end of the infusion tube. The stiffening wire extends through the entire length of the infusion tube and into the first lumen within the catheter body. Still more usually, a proximal end of the stiffening wire will not be attached to the catheter body, i.e. it will be free so that it can move distally and proximally as the catheter body and infusion wire are bent when advanced through the vasculature or other body lumen. 
     In embodiments for the treatment of the peripheral vasculature, the infusion tube typically has a length in the range from about 1 cm to about 100 cm, and a width, typically an outer diameter, in the range from about 0.3 mm to about 2.8 mm. The catheter body, in turn, has a length in the range from about 5 cm to about 150 cm, and a width, typically an outer diameter, in the range from about 0.66 mm to about 4 mm, and the central member has a length in the range from about 10 cm to about 175 cm, and a width, typically a diameter, in the range from about 0.4 mm to about 3.7 mm. In still other embodiments, the infusion tube will have ports for releasing the substance, and the ports will be formed along its length. The ports may be spaced apart by distances in the range from about 2.5 mm to about 50 mm and may have width or diameter dimensions in the range from about 0.01 mm to about 0.25 mm. In still further specific embodiments, the ports may have variable spacing or porosity along the length of the infusion tube, in order to provide or improve uniform distribution. 
     Thrombolytic and other substances may be delivered to body lumens, particularly the peripheral venous vasculature, using the catheter as described above. For example, the central member may be advanced to draw the infusion tube to a target location within the body lumen, typically a location which is at least partially occluded with thrombus. After being positioned within the treatment region, the central member is drawn proximally to foreshorten the infusion tube and radially deploy the infusion tube outwardly so that it expands toward a wall portion of the body lumen in a helical or spiral geometry, including the regions of thrombus which may be formed along the wall surface. The thrombolytic or other substance may then be introduced into the lumen of the infusion tube so that the substance infuses outwardly through the ports or other release structures toward the wall of the body lumen, typically infusing into the thrombus in order to help break up and dissolve the thrombus or other occlusive materials. 
     As described above in connection with the apparatus of the present disclosure, the infusion tube will generally have a straight configuration, i.e. will have a certain elasticity which assumes a straight configuration when neither tension nor compression are being applied. The infusion tube may be helically wrapped, coiled or spiraled around the central member to provide for a more compact profile when the central member is in an advanced position. Alternatively, the infusion tube may be substantially axially aligned with the central member when the central member is in an advanced position. The infusion tube of the present disclosure is capable of conforming to regions of widely varying diameter within the body lumen to assure good contact and/or efficient delivery of the thrombolytic and other substances into the lumen. The structure of the present disclosure is also particularly useful for treating very long regions within a body lumen, typically regions extending from about 1 cm to about 100 cm within a peripheral vein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the presently disclosed catheter are described herein with references to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a substance delivery catheter constructed in accordance with an embodiment of the present disclosure; 
         FIG. 1A  is a perspective detail view of the portion of  FIG. 1  located in the oval labeled  1 A- 1 A; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  illustrates the catheter of  FIG. 1  within a body lumen with the central member retracted and the infusion lumen radially expanded; 
         FIG. 3A  illustrates the catheter of  FIG. 1  within a body lumen with the central member advanced and the infusion lumen in a collapsed configuration; 
         FIG. 3B  illustrates an alternative embodiment of the presently disclosed catheter within a body lumen with a pair of infusion lumens radially expanded; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 1 ; 
         FIG. 5  is a side cross-sectional view of a portion of the catheter of  FIG. 1  according to an embodiment of the present disclosure; 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a side cross-sectional view of a portion of the catheter of  FIG. 1  according to an embodiment of the present disclosure; 
         FIG. 8  is a cross-sectional view taken along the line  8 - 8  of  FIG. 7 ; and 
         FIG. 9  is a side perspective view of a portion of the catheter shown in  FIG. 1 , with parts separated. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the presently disclosed catheter assembly will now be described in detail with reference to the drawings wherein like reference numerals identify similar or identical elements in each of the several views. In the discussion that follows, the term “proximal” or “trailing” will refer to the portion of a structure that is closer to a user, while the term “distal” or “leading” will refer to the portion of the structure that is farther from the user. In addition, the term spiral as used in association with the infusion tube and the central member means that the infusion tube extends along and at least partially around the central member in a helical, coiled or like configuration. 
     Referring initially to  FIGS. 1-4 , a catheter assembly  10  constructed in accordance with the principles of the present disclosure includes a handle housing  50 , a movable handle  28 , a catheter body  12 , a central member  14 , and an infusion tube  16 . Catheter body  12  extends at least partially into a distal end  54  of handle housing  50  and includes a hub  18  at its proximal end that operates to reinforce the coupling of catheter body  12  into the distal end  54  of handle housing  50 . Hub  18  may be, for example, flexible shrink wrap tubing encapsulating at least a portion of the distal end  54  of handle housing  50  and at least a portion of a proximal end of catheter body  12 . Handle housing  50  includes a first connector  20  at or near its distal end  54  for attaching to a fluid source such as a source of a thrombolytic agent to be delivered through the catheter body  12  and a second connector  21  at or near its distal end  54  for attaching to saline or other liquid for flushing the catheter body  12 . 
     As shown in the cross section of  FIG. 2 , the catheter body  12  defines a first lumen  22  that receives the thrombolytic or other agent through the port  20  and delivers it to a proximal end  24  of the infusion tube  16 . The proximal end  24  of infusion tube  16  may be shrink wrapped (not explicitly shown) and heated to bond the proximal end  24  of infusion tube  16  to first lumen  22  of catheter body  12  at a mid-joint  60  ( FIG. 1 ) via shrink wrap tubing (not explicitly shown). Catheter body  12  includes a second lumen  26  which slidably receives the central member  14  which is typically a polymeric tube or the like operably coupled to the handle  28  at its proximal end. Using the handle  28 , a physician can axially advance (see  FIG. 5 ) and proximally retract (see  FIG. 7 ) the central member  14  in order to control deployment of the infusion tube  16 , as will be described in more detail with reference to  FIGS. 3 ,  5 , and  7 . 
     The infusion tube  16  is straight in its “free” configuration, i.e. where no tension or compression is being applied to the infusion tube  16 . In certain embodiments, the polymeric material (e.g., nylon-12) from which the infusion tube  16  is made may possess sufficient stiffness and elasticity without reinforcement to perform as described herein. Alternatively, as illustrated in  FIG. 4 , a stiffening member or wire  35  that extends through at least a portion of the lumen of the infusion tube  16  may be provided to provide added rigidity to infusion tube  16 . In this scenario, a distal end of the stiffening member or wire  35  is attached at or near its distal end to the distal end of the infusion tube  16  and attached at its proximal end to the catheter body  12  within the infusion lumen  22 , as best seen in  FIG. 2 . In other embodiments, however, a proximal end of the stiffening wire  35  is unattached at its proximal end so that the proximal portion of the stiffening wire may move freely within the lumen  22  of the catheter body as the catheter itself is advanced through a body lumen. 
     As best seen in  FIGS. 1 and 3 , a one-way valve  36  (e.g., a duckbill valve) may be provided at or near the distal end  34  of the central member  14  in order to prevent back-bleed, i.e., blood flow into central member  14 . One-way valve  36  may be, for example, shrink wrapped or heat-sealed to central member  14  to reduce the cross-sectional profile of catheter assembly  10  and enable catheter assembly  10  to be introduced into a blood vessel or other body lumen. One way valve  36  also facilitates the introduction of a guide wire  38  (see  FIG. 3A ) or a medical fluid into vasculature via central member  14 . 
     The infusion tube  16  defines a lumen  17  (see  FIG. 3 ) along its length and further includes a plurality of release ports  30  which serve to release fluid from the lumen  17  into a blood vessel BV or other luminal wall. 
     Relative to infusion tube  16 , the material from which the central member  14  is made is more rigid or stiff. For example, central member  14  may be made from a polymer such as a polyimide or polyetheretherketone (“PEEK”). A distal end  32  of the infusion tube  16  is attached near distal end  34  of the central member  14  so that axial advancement of the central member  14  operates to lengthen or elongate the infusion tube  16 , as shown in  FIG. 1 , in order to reduce the cross-sectional profile of the infusion tube  16  to enable the infusion tube  16  to be introduced into a blood vessel or other body lumen. 
     Conversely, proximal retraction of the central member  14 , as shown in  FIG. 3 , radially expands the infusion tube  16  so that it moves outwardly toward the inner wall W of the blood vessel BV or other body lumen. The infusion tube  16  may be spirally or helically wrapped around the central member  14  in its deployment configuration, as shown in  FIGS. 1 and 3A . 
     As shown in  FIGS. 1 ,  3  and  3 B, one or more radio-opaque markers or bands  19  may be disposed on the catheter body, central member, and/or infusion tube  16  and/or  16   a  to allow for clear visualization of the treatment region using fluoroscopic imaging. In addition, to promote visualization of the treatment region, the infusion tube  16  may be comprised of a radiopaque filler such as barium sulfate, for example. 
     Referring now to  FIGS. 5-8 , central member  14  extends proximally from catheter body  12  at least partially within handle housing  50  and is operably coupled to a distal end  42  of movable handle  28 . Distal end  42  of movable handle  28  is configured to axially reciprocate within proximal end  52  of handle housing  50  to control movement of central member  14 . More specifically and as shown in  FIG. 5 , as movable handle  28  is axially advanced, as depicted by directional arrow “A”, tension in central member  14  is substantially reduced or eliminated such that infusion tube  16  is lengthened or elongated, as shown in  FIG. 1 . As best shown in the cross-section of  FIG. 8 , distal end  42  of movable handle  28  includes an annular bushing  45  having an outer surface for sliding engagement with an inner surface of handle housing  50 . Annular bushing  45  operates to coaxially stabilize movable handle  28  centrally within handle housing  50  during axial retraction and advancement of handle  28 . In addition, annular busing  45  acts as a seal to allow pressurized flushing of the annular space between central member  14  and catheter body  12  through second connector  21 . 
     As shown in  FIG. 7 , as movable handle  28  is axially retracted within handle housing  50 , as depicted by directional arrow “B”, infusion tube  16  is compressed by central member  14  such that infusion tube  16  shortens and radially expands toward the inner wall W of the blood vessel BV or other body lumen. 
     As best shown in the cross-section of  FIG. 6 , movable handle  28  includes a pair of longitudinal recesses  48   a ,  48   b  disposed at least partially along opposing sides of the distal end  42  of movable handle  28 . A pair of pins  46   a ,  46   b  are disposed through opposing sides of handle housing  50 . Pins  46   a  and  46   b  are configured to be received within longitudinal recesses  48   a ,  48   b , respectively, of a movable handle  28 . A plurality of indents  44  are incrementally formed within longitudinal recesses  48   a  such that upon axial translation of handle  28 , pin,  46   b  is configured to be brought into and out of registration with indents  44 . Indents  44  may be axially spaced apart in a substantially uniform manner such that proximal retraction and/or axial advancement of movable handle  28  may be incrementally controlled to provide controlled radial expansion and contraction of infusion tube  16  within a blood vessel or other body lumen. In this way, infusion tube  16  may be manipulated in a controlled manner to conform to blood vessels or body lumens of various sizes. In one embodiment, pin  46   b  is configured to receive a spring-loaded ball or detent  46   c  which allows for distinct engagement with indents  44 . Alternatively, other known flexible or resilient engagement devices may be provided to releasably retain movable handle  28  at fixed positions in relation to handle housing  50 . 
     One or both of pins  46   a ,  46   b  may be, for example, a dowel pin, a threaded fastener, a spring plunger, or the like, and may be adjusted (i.e., advanced into handle housing  50  or retracted from handle housing  50 ) as needed. In this manner, the size (e.g., circumference) of the housing and/or handle utilized may be varied without compromising interaction between pins  46   a ,  46   b  and longitudinal recesses  48   a ,  48   b.    
     As can be seen in  FIGS. 5 and 6 , longitudinal recesses  48   a ,  48   b  include a pair of distal travel limiting stops  49   a ,  49   b , respectively. In use, movable handle  28  may be advanced until pins  46   a ,  46   b  engage distal travel limiting stops  49   a ,  49   b , respectively. Similarly, as can be seen in  FIG. 7 , longitudinal recesses  48   a ,  48   b  include a pair of proximal travel limiting stops  49   c  (only one is illustrated) which engage pins  46   a ,  46   b  to limit or prevent further axial retraction of movable handle  28 . 
     As movable handle  28  is moved proximally, as illustrated by directional arrow “B” in  FIG. 7 , the central member  14  is retracted to cause the infusion tube  16  to radially expand into a generally spiral configuration, as shown in  FIGS. 3 and 3B . Since the infusion tube  16  is not pre-shaped, however, the spiral will only form as the infusion tube engages the wall surface W of blood vessel BV, thus allowing the infusion tube to conform to a variety of different diameters and irregularities within and along the surface of the wall surface W of blood vessel. Thus, it would not necessarily be expected that the infusion tube  16  will actually achieve the uniform spiral as illustrated in  FIG. 3 , instead, it will more often achieve a generally helical or spiral shape which can adapt to match the topography of the wall being engaged. 
     As shown in  FIG. 3B , catheter  10 , in certain embodiments, may include a second infusion tube  16   a  in addition to infusion tube  16 . In this scenario, infusion tube  16   a  operates substantially as described above with respect to infusion tube  16 . Infusion tube  16   a  may be spirally wrapped around the central member  14  to interweave with infusion tube  16  in the deployed state (not explicitly shown) and to radially expand with infusion tube  16  into a generally spiral configuration upon retraction of movable handle  28  ( FIG. 1 ), as shown in  FIG. 3B . 
     After deployment as shown in  FIGS. 3 and 3B , the thrombolytic or other agent may be released into the first connector  20  so that it flows through lumen  22  ( FIG. 2 ) and into the infusion tube  16  and/or  16   a  for release into the blood vessel BV or other body lumen. Saline may be delivered through second connector  21  prior to any procedure to flush lumen  26 . 
     As shown in  FIGS. 1 ,  5 , and  7 , the proximal end  40  of movable handle  28  includes a female luer  39  that provides access to a lumen  29  ( FIG. 5 ) defined through movable handle  28 . Lumen  29  communicates with the lumen defined by central member  14 . A male-type cap  43  may be removably fastened (e.g., via threading, snap-fit, slide-fit, etc.) into female luer  39  to prevent access or seal the proximal end of lumen  29 . Upon removal of cap  43 , a fluid source may be removably coupled to female luer  39  to introduce fluid such as saline into movable handle  28  and central member  14 . Further, a guide wire  38  (see  FIG. 3A ) may be inserted through lumen  29 , and into central member  14 , and through one-way valve  36  to facilitate introduction of infusion lumen  16  (and/or  16   a ) and central member  14  into the blood vessel BV or other body lumen. 
     Although the specific features of the disclosure are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the disclosure. 
     It will be understood that various modifications may be made to the embodiments of the presently disclosed delivery catheters. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.