Abstract:
The invention is directed to a guiding catheter for intraluminal procedures, such as stent delivery, balloon dilatation, atherectomy and the like, and for advancing and delivering intraluminal devices within body lumens. The guiding catheter in accordance with the invention has a multi-strand braided reinforcement layer within the wall of the catheter that has a distal end which is at an angle of at least 15° from a transverse plane perpendicular to the longitudinal axis of the catheter. This construction of the reinforced braided layer assists in the retraction of an intraluminal device back into the inner lumen of the guiding catheter. The guiding catheter may have an inner layer that has a distal end that is also at an angle with respect to a transverse plane perpendicular to the longitudinal axis.

Description:
BACKGROUND OF THE INVENTION 
     This invention generally relates to the guiding catheters for advancing and delivering intraluminal therapeutic and diagnostic devices within a patient&#39;s body lumen and more specifically to a guiding catheter for providing coronary artery access for a variety of coronary procedures including angioplasty, stent delivery and the like. 
     In a typical coronary procedure, a guiding catheter having a preformed distal tip is percutaneously introduced into a patient&#39;s peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. An elongated therapeutic or diagnostic device such as a balloon dilatation catheter or a stent delivery catheter are advanced through the inner lumen of the guiding catheter into one of the patient&#39;s coronary arteries. 
     Further details of devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.): U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson et al.) which are hereby incorporated herein in their entirety by reference thereto. 
     The typical guiding catheter has an inner tubular layer and outer tubular layer and a tubular reinforcing layer of braided wire or ribbon disposed within the wall defined by the inner and outer layer. Frequently, the braided reinforcement layer is embedded in one or both of the inner and outer layers depending upon the manufacturing processing utilized. The distal tip of the guiding catheter is preferably formed of relatively soft polymeric material to avoid traumatic engagement with the walls or the blood vessel or the coronary ostium. The soft tip may be formed of a separate tip which is secured to the distal end of the catheter or may be an extension of one or more of the layers that form the catheter walls. Typically, the braided reinforcement layer terminates proximal to the distal end of the guiding catheter and the distal end of the reinforcement layer lies in a plane perpendicular to the longitudinal axis of the catheter. The ends of the individual wires or strands at the distal end of the braided reinforcement are welded or otherwise secured to adjacent braided structure. 
     During the course of an intraluminal procedure, an intraluminal device, such as a balloon catheter, atherectomy catheter, and the like, may be introduced through the guiding catheter into the vessel or body lumen. Following the intraluminal procedure, the intraluminal device is usually withdrawn through the guiding catheter distal tip. Frequently, however, the operating portion of the intraluminal device presents a larger profile upon withdrawal than when delivered. For example, with balloon catheters for angioplasty or stent delivery, the balloons on the catheters are larger in one or more transverse dimensions after inflation than when passing through the guiding catheter which can make the withdrawal of the deflated balloon back into the interior of guiding catheter problematic. Withdrawal of the intraluminal device into the guiding catheter and then withdrawal of the guiding catheter and the device together is usually preferred. 
     What has been needed is some way to facilitate reentry of the intraluminal device back into the inner lumen of the guiding catheter. The present invention satisfies these and other needs. 
     SUMMARY OF THE INVENTION 
     The invention is generally directed to a guiding catheter for delivery of intraluminal devices which has an elongate tubular body with a multistrand braided reinforcing structure disposed within the wall forming the tubular body. The distal end of the braided reinforcing structure lies in a plane at an angle with respect to the longitudinal axis of the tubular body of the catheter that deviates from a plane perpendicular to the longitudinal axis. The deviation angle for the distal end should be at least 10° preferably at least 30° from the plane perpendicular to the catheter axis. This braided reinforcing structure facilitates the retraction of an intraluminal device, such as a balloon catheter for angioplasty or stent delivery. The angle of the braid opening may follow the braid lay-up angle (the angle characteristic of the wire or ribbon comprising the braided reinforcing layer), or may be at an angle independent of the lay-up angle. The strands (wires or ribbons) of the braided reinforcement may be bonded or welded at the braid terminal end to bond the individual wires or ribbons to the adjacent wires or ribbons. 
     The guiding catheter of the invention comprises a tubular reinforcing layer of braided wire or ribbon disposed about an inner layer and an outer layer disposed about the braided reinforcement layer. The distal end of the guiding catheter, i.e. the portion distal to the braided reinforcement layer is formed of relatively soft material to prevent traumatic engagement with the lining of body lumens through which the guiding catheter is advanced. The reinforcement layer has a plurality of wires or ribbons braided about the inner layer at a characteristic braid angle, typically in a plurality of interwoven helices of both clockwise and counterclockwise orientation with respect to the longitudinal axis of the catheter. Conventional braiding mechanisms may be used to produce the braided layer. 
     The distal end of the braided reinforcement is at an angle with respect to the longitudinal axis of the catheter so the opening at the distal end of the braided reinforcement presents a generally elliptical opening with a greater surface area than an opening which lies in a plane perpendicular to the longitudinal axis which is generally circular in shape. Note that the “opening” referenced is the effective end of the braided reinforcement, since typically the softer and more compliant tip material and/or liner extends distally of the braid. The angled and larger opening in the braided reinforcement provides less abrupt and easier transition for the balloon or other device being withdrawn into the catheter, and thus assists the withdrawal. The inner liner may also have an similarly angled terminal end. The portion of the catheter distal to the angled distal tip of the braided reinforcement structure is pliable enough so that it does not interfere significantly with the expanded distal opening provided by the angled distal tip of the reinforcement. 
    
    
     These and other advantages of the invention will become more apparent from the following detailed description of the invention and the accompanying exemplary drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic elevational view, partially in section of a conventional guiding catheter. 
     FIG. 2 is a longitudinal elevation view of the distal shaft section of a prior art guiding catheter with the outer layer partially removed to expose the braided reinforcement layer. 
     FIG. 3 is a longitudinal elevational view, similar to that of FIG. 2 of the distal shaft section of a guiding catheter which embodies features of the invention. 
     FIG. 4 depicts a longitudinal elevation view of an alternative guiding catheter having features of the invention with the outer layer removed to illustrate the braided reinforcement and inner tubular layer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 schematically depicts an elevational view of a conventional guiding catheter  10  having an elongated shaft  11  with a proximal section  12 , a distal section  13 , a port  14  in the distal end  15  and an inner lumen  16  extending therein to an in fluid communication with the port  14  in the distal end. The distal section  13  is usually provided with a particular shape which facilitates advancement to and seating within the desired opening within the patient&#39;s body such as a coronary ostium. A soft tip  17  is provided on the distal end  15 . An adapter  18  is provided on the proximal end of the catheter to provide access to the inner lumen  16 . A variety of adapters may be utilized including adapters having one or more side arms for providing flushing fluids, radiopaque fluids and the like. 
     FIG. 2 is an enlarged longitudinal elevation view of the distal section of the prior art guiding catheter  10 , with the outer layer  19  being partially removed to expose the braided reinforcement layer  20  surrounding the inner layer  21 . To simplify the drawings it should be noted that the distal section  13  is shown as being straight in FIG. 2 whereas it is shown as being curved in FIG.  1 . Moreover, the individual strands of the reinforcement layer are shown as lines, whereas they maybe formed wires or ribbons of high strength materials. The braided reinforcement layer  20  terminates proximal the distal tip  15  of the catheter shaft  11  and the distal end  22  of the braided reinforcement layer  20  lies in a plane  23  which is generally perpendicular to the longitudinal catheter axis  24 . The inner layer  21  extends beyond the distal end of the reinforcement layer  20  and has a distal end  25 . 
     FIG. 3 depicts a distal section  30  of a guiding catheter  31  embodying features of the invention which generally has an elongated shaft  32  such as that shown in FIG. 1, an inner layer 
     FIG. 3 depicts a distal section  30  of a guiding catheter  31  embodying features of the invention which generally has an elongated shaft  32  such as that shown in FIG. 1, an inner layer  33 , a multistrand braided reinforcement layer  34  disposed about the inner layer and an outer layer  35  disposed about the braided reinforcement layer  34 . The multi-strand braided reinforcement layer  34  has a distal end  36  which lies in a plane  37  at an angle with respect to a transverse plane  38  (shown in phantom) perpendicular to the longitudinal axis  39 . The multiple layered wall structure of the elongated shaft  32  shown generally has the same structure as that shown for the catheter of FIGS. 1 and 2 including having an adapter on the proximal end of the shaft and a curved distal shaft section  30 . The braided reinforcement layer  34  terminates adjacent the distal soft tip  40 . In the embodiment shown in FIG. 3, the liner layer  33  term mates adjacent the port  41  in a distal end  42  which lies in a transverse plane generally perpendicular to the catheter axis. The opening defined by the angled distal end  36  of the braided reinforcement layer is projected outwardly in a plane parallel to the angled plane  37  which has been rotated 90° to show the elliptical shape  43  presented by the opening in the distal end  36 . This provides a substantial increase in the opening area which facilitates entry of the operating ends of intraluminal devices back into the inner lumen  43  of the guiding catheter  31 . 
     Table 1 below compares the increase in effective entrance area of the braid layer distal end opening based on the angle on the opening relative to the catheter axis. The example of Table 1 is a No. 8 French guiding catheter with an inside diameter of 0.088 in. (2.2 mm). Table 1 shows that for an angle of 15°, the area is increased by about 3%. For larger angles the increase in area is greater. As the angle exceeds 30 degrees, the increase in effective entrance area exceeds 10%. 
     Note that this is the increase in the opening area of the braided reinforcement layer itself. Because the braid lies outside the liner, cross-section of the lumen is smaller than the area of the braid opening even at 0%. Thus, for substantially non-perpendicular angles (of about 15° or greater from the perpendicular), the opening angle of the tip provides an effective tip opening area substantially larger than the cross section of the lumen itself. The angle may be selected to produce the desired increase in area and the desired improvement in the pull-back or retraction function. 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Area Increase vs. Angle 
               
             
          
           
               
                               Angle 
                 Area (in 2 ) 
                 % Increase 
               
               
                   
               
             
          
           
               
                                 0 
                 0.0061 (3.94 mm 2 ) 
                 0 
               
               
                 15 
                 0.0063 (4.06 mm 2 ) 
                 3 
               
               
                 30 
                 0.0067 (432 mm 2 ) 
                 10 
               
               
                 45 
                 0.0086 (5.55 mm 2 ) 
                 41 
               
               
                   
               
             
          
         
       
     
     Thus, it is clear that the guide catheter of the invention provides for increased braid end opening area to assist in the withdrawal of an intraluminal device. By the same principal, the end opening of the liner layer may also be increased. 
     The embodiment shown in FIG. 4 illustrates an alternative construction to the distal shaft section  50  of a guiding catheter  51  embodying features of the invention. In this alternative construction the inner layer  52  extends beyond the angled distal end  53  of the braided reinforcement layer  54  and has a distal end  55  which lies in a plane  56  which is at an angle with respect to a transverse plane  57  perpendicular to the longitudinal axis  58 . The angled distal end  55  to the inner layer  52  may be aligned with the angled distal end  53  of the braided reinforcement layer  54  or at another substantial angle to the transverse plane  57  which is perpendicular to longitudinal axis  58 . 
     Guiding catheters designed for coronary artery access generally have a length from about 90 to about 110 cm, preferably about 100 cm. The wall thickness of the catheter shaft ranges from about 0.004 to about 0.01 inch. (0.1-0.25 mm) The outer polymeric layer is about 0.001 to about 0.006 inch (0.025-0.15 mm) and the inner polymeric layer is about 0.001 to about 0.002 inch (0.025-0.005 mm). The presently preferred polymeric materials are various durometers of PEBAX or nylon. Other suitable polymeric materials include polyimide and polyurethanes. A variety of other thermoplastic and thermoelastic polymers, copolymers and blends may be employed. 
     The strands which are braided to form the braided reinforcement layer may have a round (wire) or rectangular (ribbon) and their transverse dimensions depends upon the mechanical properties and the stiffness required for the braided reinforcement layer. For stainless steel wire a diameter of about 0.001 to about 0.003 inch (0.025-0.076 mm) is suitable. For stainless steel ribbon, the transverse cross sectional dimensions are about 0.0005 to 0.002 inch (0.013-0.051 mm) by about 0.003 to about 0.01 inch (0.076-0.054 mm). The maximum wall thickness of the braided reinforcing structure will be located at the cross points of the strands. The transverse and longitudinal dimensions of the catheter, the materials of construction, the number and spacing of the reinforcing strands will vary depending upon the end use of the catheter. The strands forming the braided reinforcement layer can be formed of a variety of materials include stainless steel ( 304 ) and high strength alloys such as MP35N, Elgiloy and L-605 which contain cobalt, chromium and nickel. The high strength alloys generally contain about 28 to about 65% cobalt, about 2 to about 40% nickel, about 5 to about 35% chromium and preferably also contain up to about 12% molybdenum, up to about 20% tungsten, up to about 20% iron and inconsequential amounts of other elements either as positive additions or impurities. The high strength alloy strands are preferably precipitation hardened for optimum properties. High strength plastic strands (e.g. Kevlar) or mixtures of plastic and metallic strands may also be used to form the braided reinforcing structure. Other metallic materials include superelastic NiTi alloys. 
     The adapter on the proximal end of the catheter and the nose piece for the adapter may be formed of conventional polymeric materials such as polycarbonate. 
     The inner layer of the catheter shaft is preferably formed of lubricous material or have a lubricious inner surface. The presently preferred lubricious material is a fluoropolymer. The outer layer is preferably a polyamide elastomer, e.g. a polyether block amide such as PEBAX 55 alone or blended with nylon or PEBAX materials with other durometers. 
     The materials of construction and catheter design not otherwise referred to herein can follow conventional technology. Moreover, while particular forms of the invention have been illustrated and described, it will be apparent that various modifications can be made to the invention. It will also be apparent from the foregoing that those skilled in the art will recognize that features shown in one embodiment may be utilized in other embodiments.