Abstract:
The present invention relates generally to intravascular catheters. More particularly, the present invention pertains to angioplasty catheters with a support block. According to a preferred embodiment, an angioplasty catheter comprises an inner tube having a proximal end, a distal end, and a lumen extending therethrough; an outer tube disposed over the inner tube, the outer tube having a proximal end and a distal end; a balloon coupled to the distal end of the outer tube; an inflation lumen defined between the inner tube and the outer tube, the inflation balloon in fluid communication with the balloon; and a support block coupled to the inner tube. In addition, a method for manufacturing an angioplasty catheter is disclosed.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to angioplasty catheters. More particularly, the present invention pertains to angioplasty catheters with improved resistance to balloon and catheter deformation.  
         BACKGROUND OF THE INVENTION  
         [0002]    The use of intravascular catheters has become an effective method for treating many types of vascular disease. In general, an intravascular catheter is inserted into the vascular system of a patient and navigated through the vasculature to a desired target site. Using this method, virtually any target site in a patient&#39;s vascular system may be accessed, including the coronary, cerebral, and peripheral vasculature. Examples of therapeutic purposes for intravascular catheters include percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA).  
           [0003]    The catheter may enter the patient&#39;s vasculature at a convenient location, and then be urged to a target region over a guidewire. Frequently, the path taken by a catheter through the vascular system is tortuous, requiring the guidewire to change direction frequently. Moreover, the catheter may confront a stenosis or a total occlusion when passing through the vasculature.  
           [0004]    The success of the intravascular procedure often depends on the ability of the catheter to pass the stenosis. A clinician may need to apply significant force to the catheter in order to urge it through the stenosis. If the catheter is an angioplasty catheter, the act of attempting to pass the catheter through the stenosis may cause significant damage to the catheter, and may even make it inoperable. A need, therefore, exists for an angioplasty catheter with increased structural support.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention pertains to angioplasty catheters. More particularly, the present invention comprises a refinement of angioplasty catheters that may include enhanced structural support. The present invention includes an angioplasty catheter with improved resistance to balloon deformation, improved prevention of occlusion of lumens (e.g., inflation lumens), and other refinements to the manufacturing of angioplasty catheters.  
           [0006]    In a preferred embodiment, an angioplasty catheter may comprise an inner tube, an outer tube disposed over the inner tube, a balloon coupled to the outer tube, and an inflation lumen defined between the inner tube and the outer tube that is in fluid communication with the balloon. A support block may be coupled to the inner tube. The support block may substantially prevent occlusion of the inflation lumen during coupling of the balloon to the outer tube. In addition, the support block prevents a marker band from substantially occluding the inflation lumen.  
           [0007]    The support block may include a distal region that may have a plurality of distal fins. Moreover, the support block may further comprise a proximal region that may have a plurality of proximal fins. The distal fins and/or the proximal fins may be collapsible.  
           [0008]    The support block may be coupled to the inner tube by injection molding. Alternatively, the support block may be comprised of heat shrinkable material and wherein the support block is coupled to the inner tube by heat shrinking. In an another alternative embodiment, the support block may be coupled to the inner tube by adhesive or by laser bonding. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a plan view of an inner member support block according to a preferred embodiment of the invention;  
         [0010]    [0010]FIG. 2 is a plan view of an alternative inner member support block according to a preferred embodiment of the invention;  
         [0011]    [0011]FIG. 3 is a perspective view of the inner member support block shown in FIG. 1;  
         [0012]    [0012]FIG. 4 is a perspective view of the inner member support block shown in FIG. 2;  
         [0013]    [0013]FIG. 5 is a cross-sectional view of the inner member support block shown in FIG. 3; and  
         [0014]    [0014]FIG. 6 is a cross-sectional view of a second alternative inner member support block according to a preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings represent select embodiments and are not intended to be limiting.  
         [0016]    [0016]FIG. 1 is a plan view of an inner member support block according to a preferred embodiment of the invention. A inner member support block  10  may be coupled to an inner tube  12  and may provide structural support during manufacturing or use of a catheter  14  (e.g., an intravascular catheter, an angioplasty catheter, etc.). An outer tube  16  may be disposed over inner tube  12 , defining an inflation lumen  18  therebetween. A balloon  20  may be coupled to outer tube  16 .  
         [0017]    Support block  10  may have a number of beneficial uses, including maintenance of inflation lumen  18  during manufacturing and use of catheter  14 . For example, inflation lumen  18  may be compressed or balloon  20  may become wrinkled (which may occlude inflation lumen  18  or decrease the fluid communication of inflation lumen  18  with balloon  20 ) when trying to pass catheter  14  through a tight stenosis or a total occlusion. Additionally, support block  10  may substantially prevent the displacement of balloon  20  relative to outer tube  16 , prevent a marker band  22  from occluding inflation lumen  18 , increase axial strength of catheter  14 , enhance strain relief of catheter  14 , etc. These and other uses may be found in the subsequent description.  
         [0018]    Support block  10  may be comprised of polyether block amide (PEBA) which is commerically available from Atochem Polymers of Birdsboro, Pa., and sold under the trade name PEBAX; Grilamid® (ELY 2694), which is commercially available from ______ and sold under the trade name ______; or nylon. Alternatively, support block  10  may be comprised of metals, stainless steel, nickel alloys, nickel-titanium alloys, thermoplastics, high performance engineering resins, fluorinated ethylene propylene (FEP), polymer, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyether-ether ketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysufone, perfluoro(propyl vinyl ether) (PFA), and combinations thereof. Alternative materials may be used for constructing support block  10  without departing from the spirit of the invention.  
         [0019]    Support block  10  may further comprise a distal region  24  that may include a plurality of distal fins  26 . Distal fins  26  may contact the interior surface of balloon  20  and may be collapsible. According to this embodiment, support block  10  may be able to assume a low profile appropriate for navigating catheter  14  through the vasculature of a patient. Collapsible distal fins  26  may also be useful for allowing fins  26  to be wrapped down onto inner tube  12  so that support block  10  may fit into inflation lumen  18  during the initial manufacturing of catheter  14 . However, once support block  10  is positioned outside of inflation lumen  18  at a location within balloon  20 , it would be preferred that support block  10  could not become repositioned within inflation lumen  18 .  
         [0020]    Support block  10  may be coupled to inner tube  12  at a location proximate to marker band  22 . According to this embodiment, support block  10  may substantially minimize displacement of marker band  22  during a procedure that may distort balloon  20  or otherwise apply a force to marker band  22 . This feature of support block  10  may be useful in preventing marker band  22  from moving proximally and occluding inflation lumen  18 .  
         [0021]    A number of manufacturing techniques may be used to couple support block  10  to inner tube  12 . For example, support block  10  may be coupled to inner tube  12  by adhesive, direct molding of support block  10  onto inner tube  12 , slidably disposing support block  10  onto inner tube  12 , fusing support block  10  to inner tube  12 , laser welding, heating shrinking, etc. A person of ordinary skill in the art may be familiar with a number of alternative methods for coupling support block  10  to inner tube  12  without departing from the scope of the invention.  
         [0022]    Inner tube  12  may include a proximal end  28 , a distal end  30 , and a lumen  32  extending therethrough. Lumen  32  may comprise a guidewire lumen, wherein a guidewire  34  may be disposed. A number of materials may be used to manufacture inner tube  12 , including stainless steel, nickel alloys, polymers, etc. Alternatively, materials including those listed above may be used.  
         [0023]    Outer tube  16  may be disposed over inner tube  12 , and may further comprise a proximal end  36 , a distal end  38 , and define inflation lumen  18  therebetween. Inflation lumen  18  may be in fluid communication with balloon  20 . Outer tube  16  may be comprised of a metal, a metal alloy, a polymer, or other suitable materials including those listed above.  
         [0024]    In addition to some of the utilities described above, support block  10  may also be useful for preventing deformation of sleeves used for delivering a stent. According to this embodiment, support block  10  (or a plurality of support blocks  10 ) may be disposed proximate the ends of the sleeve and may prevent the sleeves from folding back upon themselves when they are withdrawn from the stent or maintain lumen dimensionality during the process of coupling the sleeves to the stent. A description of the sleeves can be found in U.S. Pat. No. 4,950,227 to Savin et al., the entire disclosure of which is incorporated by reference.  
         [0025]    [0025]FIG. 2 is a plan view of an alternative inner member support block according to a preferred embodiment of the invention. Support block  110  is similar to support block  10  and further comprises a proximal region  140  in addition to distal region  124  and distal fins  126 . Preferably, at least a portion of proximal region  140  extends into inflation lumen  18 .  
         [0026]    Proximal region  140  may further comprise a plurality of proximal fins  142  (more clearly shown in FIG. 4) that may contact an interior surface of outer tube  16 . According to this embodiment, contact between proximal region  140  and outer tube  16  may help maintain fluid communication between inflation lumen  18  and balloon  20 . More particularly, support block  110  may help to maintain inflation lumen  18  during manufacturing of catheter  14  wherein balloon  20  may be coupled to outer tube  16  by heat bonding, laser welding, etc. The fins may also allow for the flow of inflation media (e.g., air, fluids, etc.) to freely pass from an inflation medium source disposed near proximal end  36  of outer tube  16  to balloon  20 .  
         [0027]    [0027]FIG. 3 is a perspective view of support block  10  according to a preferred embodiment of the invention. From this drawing, distal fins  26  may be seen as well as a plurality of distal valleys  44  located between fins  26 . Distal valleys  44  may be useful for allowing fluid communication between inflation lumen  18  and balloon  20 .  
         [0028]    In a preferred embodiment, support block  10  may include six distal fins  26 . However, it can be anticipated that any number of distal fins  26  may be used without departing from the spirit of the invention. For example, two, four, eight, etc. distal fins  26  may be used.  
         [0029]    Support block  10  may further comprise a proximal end  46  and a distal end  48 . Preferably, support block  10  may taper (i.e., decrease in outside diameter) from proximal end  46  to distal end  48 . As support block  10  tapers, distal fins  26  may broaden such that the width of distal fins  26  near distal end  48  is greater than the width near proximal end  46 . This taper may serve to increase perfusion from inflation lumen  18  into balloon  20  and may even permit perfusion when balloon  20  is collapsed onto support block  10 .  
         [0030]    [0030]FIG. 4 is a perspective view of support block  110  according to a preferred embodiment of the invention. From this drawing, not only can distal fins  126  and distal valleys  144  be seen, but also proximal fins  142 , and a plurality of proximal valleys  150  may be seen between proximal fins  142 . Proximal valleys  150  may be useful for maintaining fluid communication between inflation lumen  18  and balloon  20 . Similar to what is described above, any number of proximal fins  142  (e.g., two, four, six, eight, etc.) may be used without departing from the spirit of the invention.  
         [0031]    Support block  110  may further comprise an abutment surface  52 . Abutment surface  52  may abut against distal end  38  of outer tube  16  and add further support during use of support block  110 . For example, abutment surface  52  may minimize compression of balloon  18 , compression of inner tube  12 , and compression of outer tube  16 . By minimizing compression, inflation lumen  18  may be maintained.  
         [0032]    [0032]FIG. 5 is a cross-sectional view of inner member support block  10  taken proximate distal end  48 . Because of the distal taper of support block  10 , distal fins  42  may be seen in this drawing as distal-distal fins  54  (i.e., distal fins proximate distal end  48 ) and proximal-distal fins  56  (i.e., distal fins proximate proximal end  46 ). According to this embodiment, the broadening of distal fins  42  may be seen.  
         [0033]    Reference numeral  58  refers to a phantom line representing the outside diameter of support block  10  near distal end  48  before distal valleys  44  are formed. From FIG. 5, it should be clear that the width of distal fins  26  broadens near distal end  48  and that, preferably, support block  10  tapers. Similar to what is described above, this taper may serve to increase perfusion from inflation lumen  18  into balloon  20  and may even permit perfusion when balloon  20  is collapsed onto support block  10 .  
         [0034]    [0034]FIG. 6 is a cross-sectional view of a second alternative inner member support block according to a preferred embodiment of the invention. Support block  210  may comprise four fins  260  separated by four valleys  262 . According to a preferred embodiment, this cross section may represent a four-finned support block appropriate for multiple embodiments of the invention. For example, a four-finned support block may be used for distal region  24  of support block  10 , proximal region  140  of support block  110 , and combinations thereof.  
         [0035]    It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.