Abstract:
A temporary intraluminal protection apparatus for use during interventional catheterization procedures, such as angioplasty or stent deployment. A protection element is mounted near the distal end of an elongate shaft, and includes a concave proximal end. To protect distal side branches adjacent a treatment site, the distal end of an inflated balloon of a balloon catheter is receivable within the concave proximal end of the protection element. A tubular actuator slides over the shaft to engage the protection element, causing transformation thereof between an open configuration and a closed configuration.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to intraluminal devices for protecting vessels in a patient from downstream passage of embolic debris that maybe generated during an interventional procedure. The invention concerns either a filter or an occluder mounted on a tubular shaft or a guidewire.  
         BACKGROUND OF THE INVENTION  
         [0002]    A variety of treatments exists for dilating or removing atherosclerotic plaque in blood vessels. The use of an angioplasty balloon catheter is common in the art as a minimally invasive treatment to enlarge a stenotic or diseased blood vessel. When applied to the vessels of the heart, this treatment is known as percutaneous transluminal coronary angioplasty, or PTCA. To provide radial support to the treated vessel in order to prolong the positive effects of PTCA, a stent may be implanted in conjunction with the procedure.  
           [0003]    Thrombectomy is a minimally invasive technique for removal of an entire thrombosis or a sufficient portion of the thrombosis to enlarge the stenotic or diseased blood vessel and may be accomplished instead of a PTCA procedure. Atherectomy is another well known minimally invasive procedure that mechanically cuts or abrades a stenosis within the diseased portion of the vessel. Alternatively, ablation therapies use laser or RF signals to superheat or vaporize the thrombus within the vessel. Emboli loosened during such procedures may be removed from the patient through the catheter.  
           [0004]    During each of these procedures, there is a risk that emboli dislodged by the procedure will migrate through the circulatory system and cause infarction or stroke. Thus, clinicians have approached prevention of escaped emboli through use of occlusion devices, filters, lysing and aspiration techniques. For example, it is known to remove the embolic material by suction through an aspiration lumen in the treatment catheter or by capturing emboli in a filter or occlusion device positioned distal of the treatment area.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is a temporary protection apparatus for use in intraluminal procedures. The device includes a protection element mounted adjacent the distal end of an elongate flexible shaft, such as a guidewire or a hollow tube. The protection element may be pre-mounted about the shaft prior to insertion of the apparatus into the patient. Alternatively, a shaft in accordance with the invention may be inserted without the protection element, which can be slid over the shaft later. The self-expanding protection element may be a filter that captures emboli while allowing body fluid to pass therethrough, or it may be an occluder that temporarily interrupts all fluid flow through a body vessel. A proximal concavity in the protection element permits it to be located about the distal end of an angioplasty or stent delivery balloon such that distally adjacent side branches can be protected. A tubular actuatormaybe slid over the shaft to abut the protection element within the proximal concavity. Further distal advancement of the actuator causes the protection element to reversibly transform from an open configuration to a closed configuration. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where:  
         [0007]    [0007]FIG. 1 is an illustration of a temporary protection apparatus in accordance with the invention deployed adjacent an interventional catheter within a longitudinally sectioned portion of a body vessel;  
         [0008]    [0008]FIG. 2 is an illustration of a longitudinal section of a protection element in accordance with the invention;  
         [0009]    [0009]FIG. 3 is an illustration of a longitudinal section of an alternative protection element in accordance with the invention;  
         [0010]    [0010]FIG. 4 is an illustration of a longitudinal section of a temporary protection apparatus and an actuator in accordance with the invention, shown with the protection element in an open configuration;  
         [0011]    [0011]FIG. 5 is an illustration of a longitudinal section of a temporary protection apparatus and an alternative actuator embodiment in accordance with the invention, shown with the protection element in a closed configuration;  
         [0012]    [0012]FIG. 6 is an illustration of a longitudinal section of a temporary protection apparatus and a third actuator embodiment in accordance with the invention, shown with the protection element in a closed configuration;  
         [0013]    [0013]FIG. 7 is an illustration of a longitudinal section of a temporary protection apparatus and fourth actuator embodiment in accordance with the invention, shown with the protection element in a closed configuration;  
         [0014]    [0014]FIG. 8 is an illustration of a longitudinal section of a temporary protection apparatus and fifth actuator embodiment in accordance with the invention, shown with the protection element in a closed configuration. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    [0015]FIG. 1 illustrates an example of the invention during use. Body vessel  10  includes lumen  15  and side branch  17 . Catheter  20  is shown with balloon  25  inflated to dilate a narrowing in vessel  10  immediately proximal to side branch  17 . Protection apparatus  30  is deployed, or opened, against lumen  15 . In this example, shaft  35  comprises a guidewire extending through both catheter  20  and protection apparatus  30 .  
         [0016]    [0016]FIG. 2 shows protection element  40 , which comprises a tubular braid  41  that has been formed into a shape resembling two nested cones having different heights and being joined at their bases to form ring portion  42  at the proximal end. Outer body  43  is generally conical in shape and tapers in a distal direction from ring portion  42  to distal open apex  44 , which is adapted to be fixedly or slidingly coupled to shaft  35 . Inner body  45  is shorter than outer body  43  and extends there within. Inner body  45  is also generally conical in shape and tapers in a distal direction from ring portion  42  to proximal open apex  46 , which is adapted to be slidingly coupled to shaft  35 . Braid  41  comprises filaments of biocompatible thermoplastics or metals such as stainless steel or nitinol (NiTi), which can be heat treated to create mechanical memory in the shape of protection element  40 . During heating at a temperature suitable for the selected material, braid  41  can be formed into the shape of protection element  40  by being held over a shaped core, or mandrel, or it may be contained in a shaped mold cavity.  
         [0017]    Protection element  40  may be a filter device that relies on pores formed in braid  41 . The device may capture emboli within the concave proximal end formed by inner body  45 , or within the volume formed between inner body  45  and outer body  43 , or at both locations. Selected pores of inner body  45  may be enlarged (not shown) by the use of additional pins or other forming elements during the heat treating process. Enlarged inlet pores can allow embolic debris to pass through inner body  45  and be collected in the volume formed between inner body  45  and outer body  43 . Proximal apex  46  and distal apex  44  may include metal or plastic tubular bands joined to the respective body portions. For example, open apexes  44 , 46  may incorporate radiopaque metal bands soldered, brazed or glued to the respective ends of braid  41 , which can lie within, without or in abutment with the metal bands. Alternatively, solder, braze or adhesive may be used without bands to join the ends of braid  41  and thereby form open apexes  44 , 46 .  
         [0018]    Alternatively, as shown in FIG. 2, braid  41  may be a support structure for porous filter material  47 . Filter material  47  may have one or more layers secured to inner body  45  and/or outer body  43 , and the layer(s) may be located on inner surfaces, outer surfaces, both surfaces, or parts of surfaces. In one exemplary embodiment, protection element  40  may include braid  41 , which has large pores, and filter material  47  which covers only the inner surface of outer body  43 . In this example, emboli can pass easily through the large pores of inner body  45  and be caught inside outer body  43  by filter material  47 .  
         [0019]    Protection element  140 , shown in FIG. 3, is an alternative embodiment of the invention, and is similar to protection element  40  with the following differences. In protection element  140 , proximal apex  46 ′ is inverted (as compared to proximal apex  46 ) such that it lies within inner body  45 . Protection element  140  is a temporary occluder, wherein struts  48  provide support for non-porous material  49 , which interrupts the flow of bodily fluids through vessel  10 . Struts  48  may be any wire-like components that support non-porous material  49  in the memorized shape of protection elements  40 ,  140 , as described above. Struts  48  generally lie in planes radially arranged about a central axis of the apparatus, and may include wire-forms or portions of a slotted tube. Non-porous material  49  may be a flexible elastic or inelastic film attached to struts  48 . Alternatively, non-porous material  49  may comprise a continuous film coating applied to struts  48  as an elastomer dissolved in a dipping solution. Any combination of the features shown in protection elements  40 ,  140  is possible. For example, an occlusive protection element may have a braided support structure with an inverted proximal apex and a non-porous coating applied only to the outer body.  
         [0020]    [0020]FIG. 4 shows protection apparatus  30  and actuator  50 . Protection element  40  is mounted about shaft  35 , which is shown as a standard-type steerable guidewire which includes an elongate shaft having a distal region surrounded by a flexible tubular element, such as a coiled spring. Alternatively, shaft  35  can be a hollow tube, such as a catheter made of suitable medical grade plastics, metals or a combination of such materials. In the embodiment shown, distal open apex  44  and proximal open apex  46  are both slidably coupled to shaft  35 . Shaft  35  may first be introduced into the patient&#39;s vessel without protection element  40 . Then, at the discretion of the clinician, protection element  40  may be slid onto the proximal end (not shown) of shaft  35 . Actuator  50  can be fabricated as any type of pushable sheath in accordance with the field of catheters, including the use of suitable plastic and metal materials. Actuator  50  is a tubular push member slidingly disposed about shaft  35  proximal to protection element  40  and useable to advance protection element  40  to the distal end of shaft  35 . There, the coiled spring acts as stop  37 , which prevents protection element  40  from sliding distally along shaft  35 . Alternatively, stop  37  may be a band or other protrusion on shaft  35 . Optionally, distal open apex  44  maybe fixedly coupled to shaft  35  using solder, braze alloys or adhesives, such as cyanoacrylates. Distal open apex  44  may also be rotatably mounted on shaft  35  between two stops, which would prevent axial movement of distal open apex  44 . Proximal open apex  46  is slidably coupled to shaft  35 , regardless of whether distal open apex  44  is fixed or slidable. As shown in FIGS.  1 - 4 , protection element  40  is self-expanded into an open configuration such that ring portion  42  is capable of sealing engagement with lumen  15 .  
         [0021]    [0021]FIG. 5 shows protection apparatus  30  and alternative actuator  150 , which has elongate, wire-like proximal shaft  154  and relatively short tubular distal section  152 . Actuator  150  is shown having pushed proximal open apex  46  towards distal open apex  44  until protection element  40  is in a closed configuration that compactly envelopes shaft  35  and a distal portion of actuator  150 . In the closed configuration of protection element  40 , ring portion  42  is closed about actuator  50 , forming a proximal folded lip of material connecting outer body  43  with inner body  45 . The transformation of protection element  40  from an open configuration to a closed configuration is accomplished by the clinician pulling shaft  35  while pushing actuator  150 . This transformation can be reversed by removing the distal pressure applied by actuator  150  to proximal open apex  46 , which will permit protection element  40  to expand itself back into the open configuration. In the example shown, while actuator  150  pushes proximal open apex  46  distally, stop  37  restrains slidable distal open apex  44  against distal movement. Alternatively, inverted proximal open apex  46 ′ may be incorporated into the shape of protection element  40 , thus providing an exposed proximal end for selective abutment with actuator  150 .  
         [0022]    Because inner body  45  is shorter than outer body  43 , displacement of proximal open apex  46  towards distal open apex  44  applies a longitudinal tension load to inner body  45  and a longitudinal compression load to outer body  43 . These combined loads work to reduce the diameter of ring portion  42 . Under these conditions, the memorized shape imparted to protection element  40  helps keep outer body  43  from buckling or bulging radially outward. During transformation of protection element  40  between open and closed configurations, ring portion  42  may act as a rolling diaphragm, such that some material may move from one body, through ring portion  42 , to the other body. The closed configuration of protection apparatus  30  has a reduced profile, which is useful for preventing luminal injury whenever the device is moved through the patient&#39;s vessels.  
         [0023]    [0023]FIG. 6 shows protection apparatus  30  and alternative actuator  250  which has actuator distal portion  252  and actuator proximal portion  254 . Actuator distal portion  252  has a length and a diameter sized to fit within inner body  45 , when protection element  40  is in the closed configuration. At least a region of actuator proximal portion  254  that abuts actuator distal portion  252  has a diameter that nearly matches the contracted diameter of ring portion  42  when protection element  40  is in the closed configuration. The step-up in diameter between actuator distal portion  252  and actuator proximal portion  254  provides a smooth transition between actuator  250  and protection element  40 . Such a transition is useful when protection apparatus  30  is drawn proximally through the vessel  10  because it can prevent ring portion  42  from catching on anatomic protrusions or implanted devices, such as stents.  
         [0024]    [0024]FIG. 7 shows protection apparatus  30  and alternative actuator  350  which has actuator distal portion  352  and actuator sheath portion  354 . Actuator distal portion  352  has a diameter sized to fit within inner body  45  when protection element  40  is in the closed configuration. Actuator sheath portion  354  extends over a proximal region of actuator distal portion  352  to create an annular pocket capable of receiving at least a proximal portion of protection element  40 , when it is in the closed configuration. Alternatively, actuator sheath portion  354  can be a separate sheath element (not shown) slidably disposed about an actuator such as actuator  50 . Actuator sheath portion  354  can help retain protection element  40  in the closed configuration. Once protection element  40  is engaged within actuator sheath portion  354 , further advancement of actuator  350  over shaft  35  can cause protection element  40  to become more deeply engaged within the annular pocket. The action that causes deeper engagement of protection element  40  within actuator sheath portion  354  can comprise a rolling diaphragm effect wherein the closed configuration remains at the same diameter while material rolls from outer body  43 , through ring portion  42 , to inner body  45 . FIG. 8 shows protection apparatus  30  wherein alternative actuator  350 ′ has actuator distal portion  352 ′ and flared actuator sheath portion  354 ′. Actuator  350 ′ is similar to actuator  350  except that sheath portion  354 ′ is flared at its distal end to facilitate engagement with ring portion  42  when protection element  40  is in the closed configuration.  
         [0025]    The invention may be used according to the following example. Protection apparatus  30  is provided, comprising protection element  40 , having distal open apex  44  fixedly coupled to a distal region of shaft  35 . Protection element  40  comprises braid  41 , which has fine pores enabling its use as a filter. Actuator  50  is slid over shaft  35  into abutment with proximal open apex  46 . The clinician pushes on actuator  50  while pulling on shaft  35  until the normally open configuration of protection element  40  is transformed into a closed configuration with a reduced profile. In this condition, protection apparatus  30  is inserted into the patient&#39;s vasculature and advanced there through until protection element  40  is located in an artery immediately downstream of a narrowing to be treated. Actuator  50  is withdrawn over shaft  35 , allowing protection element  40  to expand itself into sealing engagement with the artery. A PTCA catheter, with its balloon deflated, is slid over shaft  35  until the balloon is within the targeted narrowing. The PTCA balloon is inflated to dilate the narrowing, and any embolic debris generated thereby is collected by protection element  40 . The PTCA balloon is deflated and the catheter is withdrawn. Actuator  50  is re-inserted over shaft  35  to transform protection element  40  from an open configuration to a closed configuration now containing emboli there within. While held in the closed configuration, protection apparatus  30  is withdrawn from the patient.  
         [0026]    While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made there in without departing from the spirit and scope of the invention. For example, the invention may be used in any intravascular treatment utilizing a guidewire where the possibility of loosening emboli may occur. Although the description herein illustrates angioplasty and stent placement procedures as significant applications, it should be understood that the present invention is in no way limited to those environments.