Abstract:
An intravascular filter device comprising a frame having an open configuration and a closed configuration, the frame comprising a plurality of elongate members each having a proximal end and a distal end, and a proximal region and a distal region and being fixedly connected at the proximal end to each other; and a filter having an open end and a closed end disposed on the frame; wherein the elongate members have a bend distal the proximal region and a helical curve over a substantial length of the distal region when the elongate members are in the open configuration.

Description:
This application is a continuation of application Ser. No. 09/972,135 filed on Oct. 5, 2001, now U.S. Pat. No. 6,755,847. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to intravascular medical devices. More particularly it relates to a device used for capturing emboli in a fluid vessel during a variety of intravascular medical procedures and a method of manufacture for that device. 
     BACKGROUND OF THE INVENTION 
     There are a number of intravascular procedures where emboli may be created in the vasculature. It may be desirable to capture these emboli before they flow downstream. 
     SUMMARY OF THE INVENTION 
     Embodiments of the invention pertain to a device for capturing emboli in fluid flowing in a body vessel lumen and a method of manufacturing the device. Certain embodiments of the invention more particularly pertain to a frame and a filter material portion of the emboli capturing system. In certain embodiments the frame comprises a plurality of proximally fixed elongate members attached to a collar which are expandable into a generally helical pattern. This generally helical pattern of elongate members is configured to open the mouth of the filter to a generally circular shape which contacts the walls of the body vessel lumen to channel the fluid through the filter. 
     The frame and collar embodiment may be manufactured from a tube of a suitable material such as Nitinol by cutting a number of slits down a substantial portion of the tube and shape setting the elongate members resulting from the slits. This method of manufacture, where the elongate members and the collar are formed from a single tube, provides a ready means of orienting the elongate members with respect to each other and may easily be adapted to frame and filter devices having a different strut configuration. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows an isometric view of emboli capturing device  110  in an expanded state according to the invention. 
         FIG. 2  shows an isometric view of emboli capturing device  110  in a contracted state according to the invention. 
         FIG. 3  shows an end view of frame  112  used in emboli capturing device  110  according to the invention. 
         FIG. 4  shows an isometric view of emboli capturing device  210  according to the invention. 
         FIG. 5  shows an isometric view of frame embodiment  312  according to the invention. 
         FIG. 6  shows an isometric view of frame embodiment  412  according to the invention. 
         FIG. 7  shows a tube  114  from which frame  112  may be manufactured. 
     
    
    
     DETAILED DESCRIPTION 
     The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several drawings. The detailed description and drawings represent select embodiments and are not intended to be limiting. 
       FIG. 1  is an isometric view illustrating an emboli capturing device  110  constructed in accordance with the principles of the invention. A frame  112  includes a plurality of elongate members  116  and a collar  118 . The plurality of elongate members  116  is fixedly connected at their proximal ends  120  to each other and may be attached to a collar  118 . Plurality of elongate members  116  is configured so that elongate members  116  will bend outward proximal a distal region  130  of elongate members  116  and bend generally helically at distal region  130 . Elongate members  116  may also bend generally in a spiral shape proximal distal region  130  of elongate members  116 . The elongate members  116  may have a region  132  between the outward bending portion and the generally helical portion whose axis will be generally parallel to the axis running through the center of emboli capturing device  110  both when elongate members  116  are in the expanded position as shown in  FIG. 1  and the compressed position as shown in  FIG. 2 . 
     A filter material  122  is disposed such that an open end  124  of filter material  122  is proximal a closed end  126  of filter material  122 . Plurality of elongate members  116  are attached to filter material  122  at points  128  proximate open end  124  of filter material  122  and extend within filter material  122 . Every elongate member  116  may be attached to filter material  122  at points  128  or optionally a lesser number of elongate members  116  may be attached to filter material  122  at points  128 . Points  128  are generally located towards the proximal end of distal region  130  and may be located at region  132  to provide an attachment location where filter material  122  is subjected to a minimum of rotational stress. 
     Emboli capturing device  110  may be disposed on a wire  134  and may be connected to wire  134  at proximal ends  120  of elongate members  116 . Filter material  122  may be attached to wire  134  at closed end  126  or may be slideably disposed on wire  134  at closed end  126  of filter material. An atraumatic tip  136  may be attached to the distal end of wire  134 . 
     Emboli capturing device  110  may be compressed within a lumen  138  of a catheter sheath  140  as depicted in  FIG. 2 . As catheter sheath  140  is slid distally over emboli capturing device  110 , a distal lip  142  of catheter sheath  140  forces elongate members  116  inward. As elongate members  116  are forced inward, points  128  proximate open end  124  of filter material  122 , which is attached to elongate members  116  at points  128 , are forced together, collapsing filter material  122  and allowing it to be drawn into catheter sheath  140 . When emboli capturing device  110  is compressed in catheter sheath  140 , the plurality of elongate members  116  is disposed longitudinally generally parallel to the axis of catheter sheath  140  and filter material  122  collapses from its expanded shape. 
     If elongate members  116  have a generally spiral shape bend as described above, when elongate members are collapsing, points  128  will rotate and twist filter material  122  during the collapsing process. 
       FIG. 3  shows an end view of frame  112  of emboli capturing device  110  in its expanded position. Elongate members  116  have a bend  154  proximal distal region  130  and a generally helical shape  156  at distal region  130  of elongate members  116 . When frame  112  is in the expanded position, the plurality of elongate members  116  may be configured so that distal ends  144  of elongate members  116  overlap the adjacent elongate member  116  such that the perimeter of open end  124  of filter material  122  is given a generally circular shape. This configuration allows filter material  122  to efficiently capture the fluid flow. 
     Elongate members  116  and collar  118  may be made of any resilient flexible material such as Nitinol, stainless steel, polymer or other suitable material. Bends  154  and generally helical shapes  156  may be molded or shape set into the material. 
     Filter material  116  may be made of a number of materials well known in the art such as polyethylene meshes manufactured by Saati Tech and Tetko, Inc. An appropriate material may allow blood cells to pass freely through while capturing emboli of a targeted size. Filter material  116  is depicted in the drawings as conical, but many shapes which have an open end and a closed end are suitable for use in embodiments of the invention. Filter material  116  may be disposed on Frame  112  such that open end  124  is either proximal or distal closed end  126 , as discussed with respect to  FIG. 4  below. 
     Wire  134  may be manufactured from a number of materials commonly used in the art to make guidewires and other wires used in the medical device industry such as stainless steel or Nitinol. 
     The manufacture of catheters suitable for use as catheter sheath  140  is well known in the art. Catheter sheath  140  may be made from a substantially flexible material such as polyethylene, polymer block amides, nylon, or other suitable material. 
     Emboli capturing device  110  may be used downstream of a treatment site in the following manner. Emboli capturing device  110  may be inserted into a deployment sheath. Elongate members  116  and filter material  122  may generally be tightly compressed and the deployment sheath may generally be sized to have the minimum outer diameter sufficient to contain emboli capturing device  110 . The deployment sheath may then be inserted into a body vessel lumen (not shown), generally percutaneously, and advanced to a location downstream of the treatment site. The deployment sheath may then be withdrawn, allowing elongate members  116  and filter material  122  to reach their expanded state. The treatment site therapy may then be performed. The treatment site therapy may be a variety of intravascular procedures including, for example, balloon angioplasty, stent insertion, or release of a therapeutic agent. If the treatment site therapy creates any emboli, the fluid flowing past the treatment site will flow through the filter material, allowing the emboli capturing device to capture the emboli. When retrieval of the device is desired a retrieval sheath may be distally advanced over the emboli capturing device, collapsing the device as described above. The retrieval sheath may generally have a larger inner diameter that the deployment sheath to accommodate any emboli that may be captured by the device. The retrieval sheath may then be removed proximally from the body vessel lumen together with the emboli capturing device. 
       FIG. 4  shows an isometric view of an emboli capturing device  210  in accordance with the invention. Like emboli capturing device  110 , a frame  212  comprises a plurality of elongate members  216  connected at their proximal ends  220  to each other. Elongate members  216  may also be connected at their proximal ends to a collar  218 . Frame  212  may have generally the same shape as frame  112 . In emboli capturing device  210  however, filter material  222  is positioned such that open end  224  of filter material  222  is distal closed end  226  of filter material  222 . Filter material  222  is attached to elongate members  216  proximate open end  224  of filter material  222  at points  228 . Points  228  may be located proximate distal ends  244  of elongate members  216 . Filter material  222  may be attached to or slideably disposed on elongate members  216  at closed end  226  of filter material  222 . 
     Emboli capturing device  210  may be disposed on a catheter  246 . Other devices such as an angioplasty balloon (not shown) may be attached to catheter  146  or deployed through a lumen  248  of catheter  246 . Closed end  226  of filter material  222  may be attached to catheter  246  and collar  218  may be slideably disposed on catheter  246 . Emboli capturing device  210  may be deployed and retrieved in a manner similar to that of the first embodiment. 
     Emboli capturing device  110  may be better adapted for use when the fluid in the body vessel lumen flows distally from the treatment site. Emboli capturing device  110  may be on a guidewire  134  and has open end  124  of filter material  122  proximal closed end  126  of filter material  122 . Emboli capturing device  210  may be better adapted for use when the fluid in the body vessel lumen flows proximally from the treatment site. Emboli capturing device  210  may be on a catheter  246  through which guidewires and treatment site devices such as angioplasty balloons may be used, and has open end  224  of filter material  222  distal closed end  226  of filter material  222 . 
       FIG. 5  is an isometric view of a frame  312  according to the invention. Frame  312  may be used with either emboli capturing device  110  or  210 . Frame  312  has elongate members  316  connected to each other at proximal end  320  and attached to a collar  318 . Collar  318  extends proximally to form a longitudinal catheter like member  352  creating a lumen  350 . If frame  312  is used with emboli capturing device  110  in lieu of frame  112 , a wire  334  may be extended through lumen  350 . Alternatively, member  352  may serve in lieu of proximal portion of wire  334  and one or more elongate members  316  may be made to extend generally parallel to the axis of the emboli capturing device in both the expanded and the contracted state to serve in lieu of the distal portion of wire  334 . If frame  312  is used with emboli capturing device  210  in lieu of frame  212 , member  352  may serve in place of catheter  240 . Frame  312  is suited to manufacturing collar  318  and member  350  from one tube although collar  318  and member  350  may also be made separately and subsequently joined. 
       FIG. 6  is an end view of an alternate frame  412  shown without filter material. Frame  412  comprises collar  418  and elongate members  416 . In this embodiment elongate member  416  have a bend  454  and a second bend  458 . This embodiment uses the constraint of a filter material  422  (not shown in this figure) and a vessel lumen wall (not shown) to form a distal region  430  of elongate members  416  into a generally helical shape. 
       FIG. 7  is an illustration of a tube  114  which may be formed into frame  112  for use in emboli capturing device  110 . The material in slots  162  may be removed to form longitudinal members  116  and collar  118 . The material in slots  162  may be removed such that slots  162  have radial walls, parallel walls or such that elongate members  116  have parallel walls. The desired configuration may then be shape-set into elongate members  116 . Variations are contemplated where different numbers of elongate members  116  are formed and where elongate members  116  have a variety of cross-sectional profiles. This method of manufacture where elongate members  116  and collar  118  are manufactured from a single tube  114  allows precise positioning of elongate members  116 . This method of manufacture may easily be adapted for use with many frame configurations, including other frame configurations disclosed herein. 
     While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims.