Abstract:
Baskets with atraumatic distal tips allow the capture of material from difficult-to-reach areas of the body, while reducing the risk of tissue damage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is based on and claims priority to provisional U.S. patent application Ser. No. 60/082,810 which was filed on Apr. 23, 1998, and U.S. provisional patent application Ser. No. 60/105,448 which was filed on Oct. 23, 1998. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The invention relates generally to medical devices for retrieving material from within a body. More particularly, the invention relates to medical retrieval baskets that have atraumatic distal ends that are contoured or tipless both to minimize the chances of damage to tissue during use and to enhance the ability of the basket to capture material (e.g., stones) disposed or lodged in “pockets” or other areas that are difficult to access in the body.  
         BACKGROUND INFORMATION  
         [0003]    Known stone retrieval devices typically have baskets that are constructed by joining multiple legs together at a base of the basket and at a distal end or tip of the basket such that a “cage” is formed. At the distal tip, the individual legs are joined by soldering, adhesives, etc. such that a protruding tip results. This protrusion or outward projection at the distal end of the basket can poke tissue and cause tissue trauma. In general, the tips or ends of known baskets protrude outward and thus can cause damage by poking or piercing tissue. Also, the protruding tips of known baskets generally do not permit access to or intimate contact with certain areas within the body such as “pockets,” and thus stones residing in such areas are difficult or impossible to retrieve with known baskets.  
         SUMMARY OF THE INVENTION  
         [0004]    It is an object of the invention to provide a medical retrieval basket that does not have a substantially protruding distal basket end or basket tip. That is, a basket according to the invention is atraumatic and does not have any significant distal protrusion or outward projection that can poke tissue, pierce tissue, or otherwise cause trauma to tissue.  
           [0005]    It is another object of the invention to provide a medical retrieval basket that permits access to and/or intimate contact with certain areas within the body such as “pockets” where material to be retrieved (e.g., stones) might reside or be lodged, impacted, or embedded. A tipless or contoured tip basket arrangement can access these areas and retrieve material from those areas whereas a conventional basket with a traumatic tip would not be able to do so because of the traumatic protruding tip that prevents intimate contact between the distal end of the basket and body tissue.  
           [0006]    It is yet another object of the invention to provide a method of using such baskets to retrieve material from within a body. The material can be biological or foreign matter. The material can be, for example, urological stones or any of a variety of other types of material found in the body.  
           [0007]    A basket according to the invention is formed by a plurality of wires, each wire forming a loop. Thus, the basket according to the invention is tipless and atraumatic, and lacks a protruding distal tip.  
           [0008]    The invention generally relates to a medical retrieval device. The device comprises a sheath, a handle, and an atraumatic basket. The sheath has a proximal end and a distal end. The handle is located at the proximal end of the sheath. The basket can remove material from a body, and it is moveable between a collapsed position when the basket is enclosed within the sheath and an expanded position when the basket is extended from the distal end of the sheath. The basket has four or more legs (e.g., six, or eight legs). At least a distal end portion of the atraumatic basket is tipless and formed by a plurality of wires, each wire forming a loop. The apex of each of the loops is positioned at the distal end of the basket. The ends of each loop are attached to one another at the basket base or to an elongated member. The loops are unattached and freely moveable at the distal end of the basket.  
           [0009]    The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.  
         [0011]    [0011]FIG. 1A illustrates one embodiment of a medical retrieval device with an atraumatic basket according to the invention with the basket in an expanded position.  
         [0012]    [0012]FIG. 1B illustrates one embodiment of a medical retrieval device with an atraumatic basket according to the invention with the basket in a collapsed position.  
         [0013]    [0013]FIG. 2A illustrates an embodiment according to the invention of a basket formed by a plurality of loops, the loops being unattached where the loops intersect at the distal end of the basket.  
         [0014]    [0014]FIG. 2B illustrates an embodiment according to the invention of another embodiment of the basket illustrated in FIG. 2A comprising more than two basket loops. 
     
    
     DESCRIPTION  
       [0015]    The basket  10  shown in FIG. 1A is the type that can be collapsed within a sheath  12  for entry into the body. A medical device or extractor  6  that includes the basket  10  of the invention also includes the sheath  12  and a proximal handle  8 . The handle  8 , sheath  12  and basket  10  illustrated in FIGS. 1A and 1B are not shown in their correct size or proportion to each other. The sheath  12  has at least one lumen  14  therein, and it extends from the handle  8  to a distal sheath end  16 . An elongated member such as a cable, coil, shaft, guidewire or mandril wire  18  extends within the lumen  14  from an actuating mechanism  4  at the device handle  8  to the base  20  of the basket  10  where the cable  18  is attached to the basket base  20 . Operation of the actuating mechanism  4  by an operator causes the basket  10  to move relative to the sheath  12  between a collapsed position within the sheath  12  as illustrated in FIG. 1B to an extended position outside of the sheath  12  where the basket  10  is open/expanded and extending beyond the distal end of the sheath  16  as shown in FIG. 1A. Alternatively, the mechanism  4  can cause movement of the sheath  12  to advance the sheath  12  over the stationary basket  10  and cable  18  combination, to thereby collapse the basket  10  within the sheath  12 , and the mechanism  4  can slide the moveable sheath  12  back to expose the stationary basket  10  and allow it to open/expand. In general, both types of basket/sheath movement configurations and related handle mechanisms are known, and can be seen in existing product designs available from, for example, Boston Scientific Corporation (Natick, Mass.). With the basket withdrawn into and collapsed within the sheath  12  as shown in FIG. 1B, the sheath  12  can be inserted into the body by an operator to a site in the body where the material to be retrieved is located (e.g., a stone in the ureter). The basket  10  is then moved relative to the sheath  12  and placed in the extended position, as illustrated in FIG. 1A, such that the basket  10  dilates the body tract and can be manipulated by the operator to entrap or capture material within the basket  10 . The basket  10  can then be moved relative to the sheath  12  to cause the legs  11   a ,  11   b ,  11   c ,  11   d  of the basket  10  to close around the material and capture it. The captured material is then withdrawn from the body along with the sheath and the basket that is holding the material.  
         [0016]    Referring to FIGS. 2A and 2B, a tipless end  22  of the atraumatic basket  10  is constructed by using single wires to form loops  24   a ,  24   b  having legs  11   a ,  11   b ,  11   c ,  11   d  extending from the apex  26   a ,  26   b  of the loops  24   a  and  24 , respectively, the apex  26   a ,  26   b  positioned at the basket distal end  22 . A plurality of pre-formed wire loops is included in a three-dimensional, atraumatic basket. In this embodiment of an atraumatic wire basket, for example, two wire loops  24   a ,  24   b  may be used to form a basket with four legs  11   a ,  11   b ,  11   c ,  11   d  as shown in FIG. 2A, and three wire loops  24   a ,  24   b ,  24   c  may be used to form a basket with six legs  11   a ,  11   b ,  11   c ,  11   d ,  11   e ,  11   f  as shown in FIG. 2B. Additional wire loops may be used to form a basket with more than the four or six legs shown. The apex  26  of each wire loop  24  intersects the apex  26  of the other wire loops  24  of the basket  10  at the basket distal end  22 . The wire loops  24  at the basket distal end are free to slide by one another, i.e., they are not affixed, fused, soldered, welded, glued, joined, secured or attached to one another. The advantages of this configuration of the basket distal end  22  is that the basket end  22  is atraumatic and provides flexibility thereby enhancing the ease by which stones are captured. The two end-sections  1 ,  1 ′ of each wire loop are brought together at the basket base  20  and held in place by welding, soldering, ligating, gluing, crimping or any other means known in the art. In one embodiment, the end-sections  1 ,  1 ′ of the wire loops are affixed (not shown) to a cable, coil, shaft, mandril wire or guidewire  18  that runs longitudinally in a sheath  12  as shown in FIG. 1A and FIG. 1B.  
         [0017]    In yet another aspect, the invention relates to a method for retrieving material from a body such as a body tract or body canal. Material (e.g., biological or foreign) can be retrieved from a body by using a tipless, atraumatic wire basket, each wire forming a loop and having an atraumatic distal basket end according to the invention. The basket of the retrieval device has an atraumatic distal end and thus allows the capture of material that is located in pockets or other difficult-to-access areas within the body. Because the distal basket end is atraumatic, it can make intimate contact with the surface of tissue, even the walls or lining of a pocket-type area, and allow the retrieval of stones or other materials that are unrecoverable with conventional tipped baskets that can cause tissue trauma and are limited in how close the basket can get to the tissue by the existence of the protruding tip. A method for retrieving material from a body includes inserting a retrieval device according to the invention into the body, moving the tipless basket into the extended position, maneuvering the basket via the proximal handle (which is located outside of the body) of the retrieval device until the material (e.g., stone) is entrapped within the three-dimensional basket structure, and then capturing the material within the basket by moving the basket relative to the sheath to close the basket legs around the material. With the material so gripped or held by the basket, the basket can be withdrawn from the body to remove the material from the body. The materials that can be captured with tipless baskets according to the invention include a calculus, or a stone, such as a kidney stone, a ureteral stone, a urinary bladder stone, a gall bladder stone, or a stone within the biliary tree.  
         [0018]    Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims.