Patent Publication Number: US-2007123926-A1

Title: Pre-curved guiding catheter with mechanically actuated occluder for embolic protection

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to an intraluminal guiding catheter used in a medical procedure, and more particularly, to a guiding catheter with embolic protection by proximal occlusion.  
     BACKGROUND OF THE INVENTION  
      A stenosis, or narrowing of a blood vessel such as a coronary artery may comprise a hard, calcified substance and/or a softer thrombus material. There have been numerous therapeutic procedures developed for the treatment of stenosis in a coronary artery. One of the better-known procedures is percutaneous transluminal coronary angioplasty (PTCA). According to this procedure, the narrowing in the artery can be reduced by positioning a dilatation balloon across the stenosis and inflating the balloon to re-establish acceptable blood flow through the artery. Additional therapeutic procedures may include stent deployment, atherectomy, and thrombectomy, which are well known and have proven effective in the treatment of such stenotic lesions.  
      The therapeutic procedure starts with the introduction of a guiding catheter into the cardiovascular system from a convenient vascular access location, such as through the femoral artery in the groin area or other locations in the arm or neck. The guiding catheter is advanced through the arteries until its distal end is located near the stenosis that is targeted for treatment. During PTCA, the distal end of the guiding catheter is typically inserted only into the ostium, or origin of the coronary artery. A guidewire is advanced through a central bore in the guiding catheter and positioned across the stenosis. A therapy device, such as balloon dilatation catheter, is then slid over the guidewire until the dilatation balloon is properly positioned across the stenosis. The balloon is inflated to dilate the artery. To help prevent the artery from re-closing, a physician can implant a stent inside the artery. The stent is usually delivered to the artery in a compressed shape on a stent delivery catheter and expanded by a balloon to a larger diameter for implantation against the arterial wall.  
      Recently, a variety of devices have been developed to address atheroembolization, which is the obstruction of blood vessels by stenotic debris released during interventional catheterization therapies such as those mentioned above. Distal protection devices (DPDs) such as filters and occluders represent one class of intravascular devices that can be used to prevent atheroembolization. A filter mounted on a guidewire or a catheter may be positioned distally of a stenotic lesion to capture and remove potentially embolic debris without causing hemostasis. Alternatively, an occluder device may be positioned distally of a stenotic lesion to temporarily stop the flow of blood, including any stenotic debris that may have become entrained in the blood. The contaminated blood is aspirated from the treated area before the occluder device is collapsed to permit resumption of blood flow.  
      Occlusion devices may also be placed proximally of a stenotic lesion to provide so-called proximal protection. Proximal occlusion devices may be used alone to prevent atheroembolization, or they may be used in conjunction with a distal occluder to form an isolated treatment chamber about the lesion to be treated. Preliminary deployment of a proximal occlusion device may be advantageous in preventing atheroembolization because advancing a treatment catheter into a tight stenosis can dislodge particulate debris; even before the stenosis is being opened.  
      One type of guiding catheter that may be utilized is described in U.S. Patent Application Publication No. 2002/0026145 A1 entitled “Method and Apparatus for Emboli Containment” to Bagaoisan et al. (“Bagaoisan”). Typical of most guiding catheters, the Bagaoisan catheter is pre-curved at the distal end to set and hold a supporting position in the vasculature while the therapeutic catheter crosses and treats the lesion. Additionally, the Bagaoisan catheter includes an expandable sealing balloon disposed around the guiding catheter distal end that, when appropriately positioned, may be inflated to provide embolic protection by proximal occlusion.  
      Another type of guiding catheter that may be utilized is described in U.S. Pat. No. 6,544,276 to Azizi. In addition to a pre-curved distal end, the guiding catheter in the &#39;276 patent teaches a self-expanding sealing member disposed around the guiding catheter distal end. A sliding sleeve encases the self-expanding sealing member and may be retracted to release same.  
      Known occluder devices typically employ an inflatable occlusion balloon with its attendant expansion apparatuses, which may make the system cumbersome to prepare and use. Additionally, multi-catheter systems used to form isolated treatment chambers may be complex to use when it is desirable for the physician to work quickly to minimize the duration of hemostasis. Furthermore, having a sleeve slide over a self-expanding sealing member can increase the overall size of a guiding catheter. Thus, a need exists for a guiding catheter having a low-profile atheroembolization prevention system that may be activated and deactivated simply and quickly during interventional catheterization procedures. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims taken in conjunction with the accompanying drawings.  
     BRIEF SUMMARY OF THE INVENTION  
      The invention provides a guiding catheter with embolic protection by artery occlusion. The guiding catheter includes an elongate shaft having a central bore and a pre-curved region adjacent the distal end. A sheath is slidably disposed about the shaft. A tubular frame is attached between the distal ends of the shaft and the sheath. The tubular frame is responsive to longitudinal movement between the ends of the frame to transform between a collapsed configuration and an expanded configuration, the expanded configuration having a centrally located major diameter. A non-porous flexible membrane extends along the frame between the frame proximal end and the major diameter such that, when the frame is in the expanded configuration, the major diameter of the frame is apposed to the artery wall and the membrane occludes the artery.  
      A method is disclosed for using the inventive guiding catheter with mechanically actuated occluder for embolic protection. The method includes providing a guiding catheter having the embodiment described above; inserting the guiding catheter into the vascular system of the patient and positioning the flexible membrane proximal to the stenotic lesion to be treated; and moving the sheath along the shaft to expand the frame and sealing membrane into sealing engagement with the wall of the artery to provide proximal occlusion of blood flow.  
      In other embodiments of the invention, the method may also include: inserting a therapeutic device through the central bore of the guiding catheter; positioning the therapeutic portion of the therapeutic device across the stenosis; and treating the stenosis with the therapeutic device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The following drawings are illustrative of particular embodiments of the invention and therefore do not limit its scope. They are presented to assist in providing a proper understanding of the invention. The drawings are not to scale and are intended for use in conjunction with the explanations in the following detailed descriptions. Like reference numerals denote like elements in the drawings, wherein;  
       FIG. 1  is a side view of a distal region of a guiding catheter in accordance with the invention, shown with an occluder in a collapsed configuration;  
       FIG. 2  is a side view of a distal region of the guiding catheter shown in  FIG. 1 , shown with the occluder in an expanded configuration  
       FIG. 3  is a transverse cross-sectional view of the guiding catheter shown in  FIG. 2 , taken along line  2 - 2 ;  
       FIG. 3  is a side view of a distal portion of the guiding catheter of  FIG. 1 , shown with the sealing member in a contracted configuration;  
       FIG. 4  illustrates a guiding catheter in accordance with the invention, shown deployed in the cardiovascular system of a patient; and  
       FIGS. 5-8  illustrate the use of the inventive guiding catheter in a diseased vessel during a typical angioplasty procedure. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.  
      The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of the invention is in the context of protection against atheroembolization during treatment of blood vessels such as the coronary, carotid and renal arteries, the invention may also be used in any other passageways where it is deemed useful to provide temporary occlusion to block fluid flow. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.  
       FIGS. 1 and 2  illustrate a distal region of one embodiment of guiding catheter  100 , including elongate shaft  105  with distal end  110 , which may comprise an optional soft tip. Bore  120  extends through shaft  105  between open proximal and distal ends, has a low-friction surface and is sized and shaped to receive and direct there through a variety of treatment devices such as guidewires and/or therapeutic devices including, but not limited to balloon catheters or stent delivery systems. Elongate sheath  125  is slidably disposed about shaft  105 , terminating adjacent shaft distal end  110 .  
      Occluder  130  is mounted about a distal region of catheter  100  and includes tubular frame  132  clingingly encased by, or impregnated by impermeable flexible membrane  134 . Frame proximal end  140  is affixed adjacent sheath distal end  145  and frame distal end  150  is affixed adjacent shaft distal end  110 . In  FIG. 1 , tubular frame  132  is shown in a collapsed configuration. In  FIG. 2 , tubular frame  132  is shown in an expanded configuration having a broadest transverse section, or major diameter  155 . Sliding sheath  125  proximally or distally along shaft  105  translates frame ends  140 ,  150  apart or together causing transformation of frame  132  between expanded and collapsed configurations. In the unrestricted expanded configuration, major diameter  155  is greater than the diameter of a branch vessel lumen being intubated, such that frame  132  causes membrane  134  to seal against the lumen wall and cause temporary stasis in the vessel, as will be described in further detail below in conjunction with  FIGS. 5-8 .  
      Catheter shaft  105  is a flexible tube that is designed to advance through a patient&#39;s vasculature to remote arterial locations without buckling or undesirable bending. As is well known to those of skill in the art, catheter shaft  105  includes a pre-formed distal curve that can provide enhanced “backup support” as therapeutic catheters are advanced through bore  120  of guiding catheter  100  and across a stenosis. Any one of a number of pre-formed curve shapes may be incorporated into guiding catheter  100 , such as Judkins-type or Amplatz-type curves, as non-limiting examples. Curve  160  may be pre-formed utilizing various known methods including, but not limited to, the method disclosed in U.S. Pat. No. 5,902,287 entitled “Guiding Catheter and Method of Making Same.” 
      Catheter shaft  105  may be constructed of one or more flexible biocompatible materials, including, but not limited to, polyethylene, polypropylene, polyurethane, polyesters, or polyethylene block amide copolymer. Catheter shaft  105  may also include a layer of braided filaments that resist kinking and enhance longitudinal transmission of rotation. To further aid in advancing guiding catheter  100  through the patient&#39;s vasculature, it may be desirable to vary the stiffness of catheter shaft  105  by varying the braid pitch, by varying the properties of materials used in construction, or by combining both techniques.  
      Bore  120  of guiding catheter  100  may provide a slippery interior surface for reducing frictional forces between the interior surface and devices that may be moved through bore  120 . In one exemplary embodiment, the interior surface is provided with a slippery coating, such as a silicone compound or a hydrophilic polymer. In another exemplary embodiment, the interior surface includes a liner formed from a slippery material. Those with skill in the art may appreciate that any one of numerous low-friction, biocompatible materials such as, for example, fluoropolymers (e.g. PTFE, FEP), polyolefins (e.g. polypropylene, high-density polyethylene), or polyamides, may be used for bore  120 .  
      Sheath  125  may comprise flexible biocompatible materials such as those mentioned above with respect to shaft  105 . Furthermore, to provide a small overall diameter of guiding catheter  100 , sheath  125  may comprise thin-walled thermoset polyimide tubing, which has sufficient stiffness to provide precise manual actuation of occluder  130  by pushing or pulling sheath  125  relative to shaft  105 , as indicated by the force vectors in  FIGS. 1 and 2 .  
      Tubular frame  132  may comprise braided filaments or alternatively, an expandable array of struts formed by making parallel slots a solid-walled tube (not shown). The braid filaments or tubing of frame  132  may be made from a high-modulus thermoplastic or thermo-set plastic, nitinol (TiNi), stainless steel or a work-hardenable super alloy comprising nickel, cobalt, chromium and molybdenum. Frame proximal and distal ends  140 ,  150  may be fixed to sheath  125  and catheter shaft  105 , respectively, by any suitable manner known in the art, such as epoxy or cyanoacrylate adhesives. Radiopaque material may be incorporated into one or both of the adhesive bonds, either as a solid marker band or as particulate filler material in the adhesive. Frame proximal end  140  may abut or be located directly around the distal end of sheath  125 . Alternatively, proximal end  140  may be spaced somewhat proximally from the distal end of sheath  125 , as illustrated in  FIGS. 1 and 2 , to provide an intermediate step in both diameter and stiffness along the assembly.  
      Sealing membrane  134  has sufficient flexibility such that when it is actuated or expanded it will form a seal between sheath  125  and the inner wall of the artery or desired vessel. When membrane  134  is contracted or deactivated it will lie snugly against frame  132 . Membrane  134  may be formed from an elastic material such as latex, silicone elastomer, or other viscous forms of natural and synthetic rubbers such as butadiene/acrylonitride copolymers, copolyesters, ethylene vinylacetate (EVA) polymers, ethylene/acrylic copolymers, ethylene/propylene copolymers, polyalkylacrylate polymers, polybutadiene, polybutylene, polyethylene, polyisobutylene, polyisoprene, polyurethane, styrenebutadiene copolymers, and styrene-ethylene/butylene-styrene.  
      Alternatively, membrane  134  may be formed from an inelastic material that is thin, flexible and foldable, such as polyamide, polyethylene, polyethylene terephthalate, polyolefin, polypropylene, or polyvinyl chloride. As shown in  FIG. 3 , sealing membrane  134  may be attached around the outer surface of tubular frame  132  using any suitable manner known in the art, such as adhesive bonding or heat bonding. The proximal end of membrane  134  may be sealingly affixed about frame proximal end  140 , or sealingly affixed to sheath  125  adjacent to frame proximal end  140 . Alternatively, membrane  134  may be impregnated into the interstices of tubular frame  132 , using known techniques such as thermoplastic molding or solvent dipping or casting.  
      Membrane  134  covers a proximal region of tubular frame  132  by extending distally from frame proximal end  140  at least as far as major diameter  155 . The distal region of tubular frame  132  that is not covered by membrane  134  allows unrestricted fluid flow through the interstices of frame  132 , thus permitting rapid transformation of occluder  130  between the collapsed and expanded configurations.  
      As shown in  FIG. 4 , connector fitting  165  is coupled to, and provides a functional access port at the proximal end of guiding catheter  100 . Fitting  165  is attached to shaft  105  and has a central opening in communication with bore  120  to allow passage of therapeutic devices there through. Connector fitting  165  may be made of metal or of a hard polymer (e.g. medical grade polycarbonate, polyvinyl chloride, acrylic, acrylonitrile butadiene styrene (ABS), or polyamide) that possesses the requisite structural integrity, as is well known to those of skill in the art.  
      Control fitting  170  is coupled to the proximal end of sheath  125  and has a central opening to allow shaft  105  to slide there through. Fitting  170  provides an enlarged component for the clinician to manually grasp when sliding sheath  125  along shaft  105  to actuate occluder  130 . Optionally, fitting  170  may include a mechanism (not shown) for temporarily locking shaft  105  and sheath  125  in their relative longitudinal positions that define either the expanded or collapsed configurations of occluder  130 . Fitting  170  may be made of the same or similar material as those mentioned above with respect to connector fitting  165 .  
      An exemplary method of using guiding catheter  100  will now be described.  FIG. 4  illustrates guiding catheter  100  positioned within patient&#39;s vascular system  400  for use with a therapeutic device. The clinician confirms that occluder  130  is in the compressed configuration and inserts the distal end of guiding catheter  100  through introducer sheath  460  into vascular system  400 , typically through a femoral artery in the groin area. Guiding catheter  100  is advanced through aorta  465  until the distal end of the catheter is located in the ostium of targeted branch artery  470 . In the example shown, branch artery  470  is a patient&#39;s left coronary artery.  
      If the clinician elects to use proximal occlusion during the intervention, then the distal end of guiding catheter  100  is inserted into artery  470  until occluder  130  is substantially within artery  470 , as illustrated in  FIG. 5 . At least the portion of occluder  130  that will become, when in the expanded configuration, major diameter  155  is positioned distal to the ostium. The clinician manually separates connector fitting  165  and control fitting  170  to actuate occluder  130 , thus transforming it from the collapsed configuration to the expanded configuration, which provides a seal between occluder  130  and vessel wall  425  and create hemostasis within artery  470 , as illustrated in  FIG. 6 . Connector fitting  165  and control fitting  170  are manually separated according to the clinician&#39;s preference: Shaft  105  may be held stationary in artery  470  while sheath  125  is advanced, or sheath  125  may be held stationary in artery  470  while shaft  105  is withdrawn.  
      A therapeutic device, such as balloon dilatation catheter  480 , including a dilatation balloon, is advanced through bore  120  until the balloon reaches a desired position within stenosis  475 , as illustrated in  FIG. 7 . The dilatation balloon is then inflated to dilate stenosis  475 . Balloon dilatation catheter  480  may then be removed, and blood may be aspirated from artery  470 , including any debris released during the dilation of stenosis  475  as shown in  FIG. 8 . Aspiration may be performed either directly into bore  120  of guiding catheter  100  or, alternatively, into an aspiration catheter (not shown), which may be advanced to the treated area within artery  470 . As will be recognized by those of skill in the art, aspiration during proximal occlusion of an artery requires retrograde blood flow in artery  470 . If retrograde flow through the capillary bed is insufficient to support aspiration of the potentially contaminated blood, then simultaneous flush and aspiration can be established through an aspiration catheter and guiding catheter  100 . Lastly, guiding catheter  100  is withdrawn from vessel lumen  420 .  
      While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.