Abstract:
A flexible elongate device having a distally mounted occluder for collecting particulate debris in a body lumen. The occluder containing a fixed amount of fluid is reversibly expandable by push-pull actuation from a contracted configuration to a deployed configuration wherein the occluder is expanded into sealing engagement with the wall of the body lumen. The occluder has a distal end axially secured to an elongate inner member and a proximal end attached to a distal end of an outer tubular member. The occluder has an impermeable occluder casing for containing the occluder fluid. The elongate inner member is slidable within the outer tubular member such that relative longitudinal movement between the elongate inner member and outer tubular member changes the length of the occluder and thus redistributes the occluder fluid within the occluder casing to transform the occluder between its contracted and deployed configurations.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates generally to intraluminal devices for containing particulate in the vessels of a patient. More particularly, the invention relates to a catheter having a mechanically actuated fluid-column occluder for containing emboli in a blood vessel during an interventional vascular procedure. Furthermore, the invention concerns a mechanically actuated fluid-column occluder mounted on a guidewire that can also be used to direct an interventional catheter to a treatment site within a patient.  
       BACKGROUND OF THE INVENTION  
       [0002]     Catheters have long been used for the treatment of diseases of the cardiovascular system, such as treatment or removal of stenosis. For example, in a percutaneous transluminal coronary angioplasty (PTCA) procedure, a catheter is used to insert a balloon into a patient&#39;s cardiovascular system, position the balloon at a narrowed treatment location, inflate the balloon to expand the narrowing, and remove the balloon from the patient. Another example is the placement of a prosthetic stent in the body on a permanent or semi-permanent basis to support weakened or diseased vascular walls to avoid closure or rupture thereof.  
         [0003]     These non-surgical interventional procedures often avoid the necessity of major surgical operations. However, one common problem associated with these procedures is the potential release into the bloodstream of atherosclerotic or thrombotic debris that can embolize distal vasculature and cause significant health problems to the patient. For example, during deployment of a stent, it is possible for the metal struts of the stent to cut into the stenosis and shear off pieces of plaque which become embolic debris that can travel downstream and lodge somewhere in the patient&#39;s vascular system. Further, particles of clot or plaque material can sometimes dislodge from the stenosis during a balloon angioplasty procedure and become released into the bloodstream.  
         [0004]     Medical devices have been developed to attempt to deal with the problem created when debris or fragments enter the circulatory system during vessel treatment. Practitioners 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 capturing emboli in a filter positioned distal of the treatment area.  
         [0005]     Alternatively, an occlusion device may be deployed distally or proximally of the treatment area to block the flow of contaminated blood, which can then be aspirated along with the embolic debris contained therein. Known occlusion guidewires include an occluder membrane surrounding an expandable mechanical structure that is actuatable by push-pull action of a core wire through an outer tubular member. However, such expandable mechanical structure can be complex to fabricate and can add undesirably to the overall collapsed profile of the occlusion guidewire.  
         [0006]     Other known occlusion catheters or guidewires include an inflatable occlusion balloon located adjacent the distal end of a hollow guidewire. Dilute radiopaque contrast agent is forced through an inflation lumen to inflate and deflate the occlusion balloon. However, operating the balloon may take longer than desired due to the viscosity of the inflation medium, the small size of the inflation lumen, and the requirement to attach, detach and operate one or more inflation accessories at the proximal end of the catheter or guidewire. Accordingly, there is a need for a simplified, low-profile embolic protection device.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     The present invention is a protection device for collecting/containing embolic debris in a body lumen. The protection device includes an outer tubular member, an elongate inner member longitudinally slidable within the outer tubular member, and a mechanically actuated occluder The occluder has a proximal end fixedly sealed about a distal end of the outer tubular member, a distal end axially secured to the elongate inner member and a fixed amount of fluid contained therein. In an embodiment of the present invention, a sliding seal accommodates relative sliding movement between the inner and outer members and prevents leakage of occluder fluid from the occluder. In another embodiment, the occluder has an annular cross-section defined by the coaxial arrangement of an inner and an outer tubular wall. The annular space between the inner and outer walls is filled with a fixed amount of occluder fluid. The inner tubular wall isolates the core wire from occluder fluid. Upon positioning of the occluder within the body lumen distally or proximally of the treatment site, proximal movement of the elongate inner member relative to the outer tubular member forces the ends of the occluder toward each other, thus redistributing the occluder fluid radially outward to deploy the occluder into sealing apposition with a wall of the body lumen.  
         [0008]     In various embodiments of the present invention, the occluder may be comprised of an impervious elastomeric material filled with a biocompatible fluid. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The drawings are not to scale.  
         [0010]      FIG. 1  is a side view of a distal protection device in accordance with an embodiment of the present invention.  
         [0011]      FIG. 2  is a partial cross-section of a distal end of the distal protection device of  FIG. 1  within a patient&#39;s vascular anatomy.  
         [0012]      FIG. 3  is a partial cross-section of a distal end of the distal protection device of  FIG. 1  in accordance with another embodiment of the present invention.  
         [0013]      FIG. 3A  is a transverse cross-section of the distal protection device of  FIG. 3  taken along line A-A.  
         [0014]      FIG. 3B  is an enlarged view of a distal end of the distal protection device of  FIG. 3  in accordance with another embodiment of the present invention.  
         [0015]      FIG. 4  illustrates a distal end of the distal protection device of  FIG. 1  with the occluder in its deployed configuration within the patient&#39;s vascular anatomy.  
         [0016]      FIG. 5  is a partial cross-section of a distal end of a protection device within a patient&#39;s vascular anatomy according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     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.  
         [0018]     While the following description generally refers to a distal protection device, it should be understood that the invention is also applicable to a proximal protection device, wherein the occluder may be deployed proximally of a treatment site to block flow upstream of the site. A treatment apparatus, such as a catheter, may be delivered via a through lumen in the proximal protection device to provide therapy at the site. See lumen  509  in  FIG. 5 . Debris generated during the therapy will not move downstream to embolize because of the temporary stasis in the vessel. Fluid that may be contaminated with debris can be aspirated via the through lumen before the occluder is contracted to allow fluid flow to resume.  
         [0019]     The present invention is a temporary distal protection device for use in minimally invasive procedures, such as vascular interventions or other procedures, where the practitioner desires to capture and remove embolic material that may be dislodged during the procedure. As shown in  FIGS. 1 and 2 , distal protection device  100 , viz, occluder system  100 , includes an elongate tubular member, or catheter shaft,  102 , a core wire  108  slidably extending there through, and a hub  110 . Core wire  108  extends within a lumen  207  of tubular member  102  from a proximal end  104  to a distal end  101  thereof. A seal  205  is secured to distal end  101  of tubular member  102  and slidingly seals about core wire  108  to retain fluid on the distal, or occluder side of seal  205 , like a rod-type seal for a hydraulic cylinder. Alternatively, seal  205  may take the form of a cap that sealingly fits over distal end  101  of tubular member  102 . A fluid-column occluder  106  for containing a fixed amount of biocompatible fluid  212  is joined to distal end  101  of tubular member  102  and core wire  108 , as described below.  
         [0020]     One alternative to rod-type seal  205  is a seal fixed about core wire  108  to slidingly seal anywhere along the interior surface of tubular member  102  to retain fluid on the distal, or occluder side of the seal, like a piston-type seal (not shown) for a hydraulic cylinder. In another alternative embodiment, a rolling diaphragm-type of seal (not shown) can be disposed between tubular member  102  and core wire  108 . A seal that allows movement between core wire  108  and shaft  102  may be located at distal end  101 , e.g. seal  205 , at proximal end  104 , or anywhere in lumen  207  between shaft ends  101 ,  104 . If a seal is located at shaft proximal end  104  or within lumen  207  proximally of shaft distal end  101 , then the portion of lumen  207  distal to the seal will be in fluid communication with the interior of occluder  106  and thus will also contain occluder fluid  212 , which may act as a lubricant between core wire  108  and shaft  102 .  
         [0021]     Fluid-column occluder  106  has a proximal end  214  and a distal end  216 . Occluder distal end  216  is axially secured to core wire  108  and occluder proximal end  214  is attached to distal end  101  of tubular member  102 . Occluder ends  214 ,  216  may be fixedly attached to tubular member  102  and core wire  108 , respectively, by use of a bonding sleeve, and/or an adhesive, as would be apparent to one of ordinary skilled in the relevant art. Occluder  106  is filled with occluder fluid  212  in the form of gas, liquid, semisolid, i.e. a gel, or combinations thereof. Non-limiting examples of suitable fluids  212  are carbon dioxide gas, saline and silicone oil. Other amorphous, fluid-like substances may be utilized, as long as the substance is biocompatible and is capable of redistributing, deforming or flowing in response to forces applied thereto during push-pull actuation of occluder system  100 . In a further embodiment, fluid  212  may comprise suspended radiopaque particles or a dilute or undiluted x-ray contrast agent to aid in fluoroscopic observation of the occluder in vivo. Optionally and/or in addition to fluoroscopic material within fluid  212 , radiopaque markers (not shown) may be placed on proximal and distal ends  214 ,  216  of occluder  106  to aid in fluoroscopic observation during manipulation thereof.  
         [0022]     Core wire  108  may be made from a metal, such as nitinol, stainless steel, or cobalt-chromium superalloy wire. In an embodiment of the present invention (not shown), core wire  108  may be tapered at its distal end and/or be comprised of one or more core wire sections of different materials. Core wire  108  may be centerless-ground to have several diameters in its profile in order to provide regions of different stiffnesses with gradual transitions there between. Core wire  108  has a proximal end  109  that extends outside of the patient from proximal end  104  of tubular member  102 . Core wire  108  may also include a coiled tip portion, such as, coiled tip portion  326  shown in  FIG. 3 , or may include a flexible coil spring that is formed from a round or flat coil of stainless steel and/or one of various radiopaque alloys, such as platinum, as is well known to those of skill in the art of medical guidewires.  
         [0023]     In another embodiment of the present invention, tubular member or catheter shaft  102  may be constructed of multiple shaft components (not shown) of varying flexibility to provide a gradual transition in flexibility. Such a shaft arrangement is disclosed in U.S. Pat. No. 6,706,055, which is incorporated by reference herein in its entirety. In addition, a liner or axial bearings (not shown) as disclosed in the &#39;055 patent may be utilized between core wire  108  and outer shaft  102  in order to facilitate sliding movement there between during expansion and collapse of occluder  106 . In another embodiment, tubular member  102  may be a hollow tube enabling distal protection device  100  to also function as a medical guidewire.  
         [0024]     Tubular member  102  may include a thin-walled, tubular structure of a metallic material, such as stainless steel, nitinol, or a cobalt-chromium superalloy. Such metallic tubing is commonly referred to as hypodermic tubing or a hypotube. Metallic tubing formed from other alloys, as disclosed in U.S. Pat. No. 6,168,571, which is incorporated by reference herein in its entirety, may also be used in the tubing of the present invention. In the alternative, outer shaft  102  may include tubing made from a thermoplastic material, such as polyethylene block amide copolymer, polyvinyl chloride, polyethylene, polyethylene terephthalate, polyamide, or a thermoset polymer, such as polyimide.  
         [0025]     Fluid-column occluder  106  is comprised of an occluder casing  211  that contains occluder fluid  212 . Occluder casing  211  is comprised of a biocompatible elastic material that is impermeable to bodily fluids, as well as to the contained occluder fluid  212 . In an embodiment of the present invention, occluder casing  211  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. Occluder  106  may be made, completely or partially, self-expanding, meaning that occluder  106  may be made to have a mechanical memory to return from the radially contracted or columnar configuration to the radially expanded or deployed configuration, as shown in  FIG. 4 . Such mechanical memory can be achieved in occluder  106  by making occluder casing  211  in the shape of the deployed configuration, as by casting or blow molding occluder casing  211  inside a hollow mold, or by forming occluder casing  211  over a removable mandrel, e.g. by dipping or thermoforming.  
         [0026]     Occluder  106  is sized and shaped such that when it is deployed, as shown in  FIG. 4 , its greatest diameter will be expanded into sealing contact with the inner surface of the blood vessel wall into which it is placed. The inner surface contact is maintained around the expanded circumference to prevent any emboli from escaping past occluder  106 . In the embodiment shown in  FIG. 2 , occluder casing  211  is of a substantially cylindrical or columnar, radially contracted shape filled with occluder fluid  212 , as is occluder casing  511  shown in the embodiment of  FIG. 5  that is described further below.  
         [0027]     Alternatively, as shown in the embodiment of  FIGS. 3, 3A  and  3 B, occluder casing  311  of occluder  306  has an annular cross-section defined by the coaxial arrangement of an inner tubular wall and an outer tubular wall. The annular space between the inner and outer walls is closed at occluder proximal and distal ends  314 ,  316  and the fixed internal volume thus defined is filled with a fixed amount of occluder fluid  212 , as measured by volume or mass. The inner tubular wall defines a central lumen  313  that surrounds core wire  108  and isolates core wire  108  from occluder fluid  212 . As in the embodiment of  FIG. 2 , occluder distal end  316  is axially secured to core wire  108  and occluder proximal end  314  is attached about distal end  101  of tubular member  102 . However, because occluder fluid  212  is contained within annular occluder casing  311  and does not make contact with the portion of core wire  108  within lumen  313 , no seal or sealing member is needed to seal distal end  101  of tubular member  102 .  
         [0028]     In a further embodiment as shown in  FIG. 3B , occluder distal end  316  may be axially secured to and rotatable with respect to core wire  108 . Occluder distal end  316  may be affixed to a cylindrical collar or bearing  324 , such that core wire  108  may rotate relative to occluder  306  and tubular member  102 . The bearing may be held in its axial position relative to core wire  108  by proximal and distal stops  320 ,  322 , which are fixedly attached to core wire  108 .  
         [0029]     Distal protection device  100  is transformable between its radially contracted and deployed configurations by relative movement between proximal and distal ends  214 ,  216  of fluid-column occluder  106 . Distal protection device  100  is tracked through a patient&#39;s vasculature with occluder  106  in its low profile, contracted form, as shown in  FIG. 2 . Once occluder  106  is situated distal of the treatment site, occluder  106  is transformed into its deployed configuration by pulling core wire  108  proximally within tubular member  102 , or by pushing tubular member  102  distally over core wire  108 . This push-pull actuation draws ends  214 ,  216  toward each other, thus shortening the length of occluder  106  and redistributing occluder fluid  212  radially outward within occluder casing  211  to thereby bring occluder  106  into contact with the walls of the vessel lumen, as shown in  FIG. 4 .  
         [0030]     If occluder fluid  212  is a gas, then the initial fixed amount, i.e. fixed mass, of fluid  212  may be compressed from its initial volume to a somewhat smaller volume and corresponding increased internal pressure resulting from shortening the length of occluder  106  during push-pull actuation. However, with proper selection of elastic material and thickness for occluder casing  211 , a gas-filled embodiment of occluder  106  will expand into its deployed configuration in response to push-pull actuation of distal protection device  100 . Occluder  106  is contracted for removal from the body lumen by reversing the push-pull deployment actuation, i.e. by distally advancing core wire  108  relative to tubular member  102  or by proximally drawing tubular member  102  over core wire  108 . As described above, fluid-filled occluder  106  is transformable between contracted and deployed configurations by mechanical actuation, not by adding fluid to, or removing fluid from, the interior of occluder  106 .  
         [0031]      FIG. 5  illustrates a further embodiment of the present invention situated within a body lumen, with an embolic occluder  506  in its contracted configuration. Distal protection device  500  includes occluder  506  attached at a proximal end  514  to a distal end  501  of an outer tubular member or shaft  502  and attached at a distal end  516  to an inner tubular member or shaft  503 . Inner tubular member  503  includes a lumen  509  to slidably accommodate a therapy device (not shown) and/or a guidewire  508  therein, whereas outer tubular member  502  includes a lumen  507  to slidably accommodate inner tubular member  503  therein. Occluder ends  514 ,  516  may be joined to outer and inner tubular members  502 ,  503 , respectively by a bonding sleeve, and/or an adhesive, as would be apparent to one of ordinary skilled in the relevant art. Occluder casing  511  of occluder  506  may be formed from the same elastic materials described above with respect to occluder casing  211 , such that occluder proximal end  514  forms integral seal  505  for accommodating sliding movement of inner tubular member  503  there through without leakage of fluid  512  from occluder  506 . Alternatively, distal protection device  500  may include a seal positioned and secured between inner and outer tubular members  503 ,  502 , as described above with reference to seal  205  in the embodiment of  FIG. 2 .  
         [0032]     Distal protection device  500  is transformable between its deployed and contracted configurations by relative movement between proximal and distal ends  514 ,  516  of occluder  506 . Distal protection device  500  is tracked through a patient&#39;s vasculature over guidewire  508  with occluder  506  in its contracted or columnar configuration, as shown in  FIG. 5 . Once occluder  506  is situated distal of the treatment site, occluder  506  is transformed into its deployed configuration by pulling inner tubular member  503  proximally relative to outer tubular member  502 . This push-pull actuation draws ends  514 ,  516  toward each other, thus shortening the length of occluder  506  and redistributing occluder fluid  512  radially outward within occluder casing  511  to thereby bring occluder  506  into contact with the walls of the vessel lumen.  
         [0033]     Similarly to the embodiment shown in  FIG. 2 , occluder  506  is contracted for removal from the body lumen by distally advancing inner shaft  503  relative to outer shaft  502 . Inner tubular member  503  and outer tubular member  502  may be of any construction or material previously described with reference to tubular member  102 .  
         [0034]     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.