Abstract:
A medical retrieval device, and related method, for removing material (such as calculi and stones) from the body of a patient has the ability to capture and readily release material. The retrieval device includes a basket having at least one loop with first and second ends including a plurality of bead elements. The first end of the loop is immovable and the second end of the loop is slideably movable.

Description:
TECHNICAL FIELD  
         [0001]    The invention relates generally to surgical retrieval devices for removing biological or foreign material from the body. More particularly, the invention relates to medical retrieval devices for capturing and releasing material such as stones from a body lumen.  
         BACKGROUND INFORMATION  
         [0002]    Medical retrieval devices generally are used to retrieve biological and foreign material from the body including stones. Such medical retrieval devices include, for example, retrieval baskets, and may be used through an endoscope or a laparoscope.  
           [0003]    One type of known device has a sheath and a retrieval assembly such as a basket that is movable in and out of the sheath. When the basket is within the sheath, the basket assumes a collapsed, reduced diameter profile. When the sheath is retracted relative to the basket or the basket is moved beyond the end of the sheath, the basket expands to a relatively larger diameter than when the basket is enclosed within the sheath. Generally, the contour of known baskets is round or oval and is formed by a plurality of legs.  
           [0004]    With many known retrieval devices, it is technically difficult to release captured material such as a stone from the retrieval assembly once the stone is captured. In some patients, a cicatrix, for example, or some other constriction that reduces the diameter of the lumen of the tract may form in the tract in which the stone is lodged because of recurrent trauma caused by the stone to the lining of the tract. The narrowed lumen of the tract may not be so narrow so as to interfere with insertion of a retrieval device while the retrieval device is in a collapsed position. However, after the retrieval device is inserted into the tract, the retrieval assembly expanded, and the stone captured within the device, the diameter of the retrieval assembly containing the stone may exceed the inner diameter of the narrowed lumen of the tract or the inner diameter of the orifice of the tract into which the retrieval device is inserted. If an excessive pulling force is used by the operator in an attempt to remove the retrieval device and stone, the retrieval device may traumatize the orifice or the lining of the tract or, worse, perforate the tract. In addition, the retrieval device may assume an everted configuration causing damage upon being withdrawn from the tract. Under these conditions, the stone must first be released from the retrieval device followed by withdrawal of the collapsed retrieval device from the tract. If the stone can not be released from the retrieval device, more invasive, surgical approaches are required to disengage the stone from the retrieval device and to remove the retrieval device from the body tract.  
           [0005]    With most, if not all, current medical retrieval device designs, it is difficult to disengage the stone or other material from the retrieval assembly so that the retrieval device can be collapsed and then removed from the body. A medical retrieval device that is capable of collapsing to release a stone captured by the device in the body of a patient is needed. The device described herein addresses this need.  
         SUMMARY OF THE INVENTION  
         [0006]    In general, the invention described herein provides a medical retrieval device including an assembly, such as a retrieval basket for capturing material in the body of a patient and optionally releasing the material in the patient&#39;s body. The retrieval device according to the invention can be used in urological, hepatobiliary, cardiovascular or endoscopic applications by procedures that are minimally invasive. The medical retrieval device described herein may be manufactured from materials that are substantially resistant to the energy emitted from holmium lasers. In a specific application of the device according to the invention, the retrieval device can be used for capturing stones within a body tract such as the biliary or urinary tract.  
           [0007]    In general, in one aspect, the invention features a medical retrieval device comprising at least one loop including a plurality of beads. The loop has a first end and a second end. The first end of the loop is immovable and the second end of the loop is slideably moveable. The slideable movement of the second end of the loop moves the loop for capturing the material in the body of the patient.  
           [0008]    The medical device can include a sheath having a distal portion, a proximal portion, and defining a lumen.  
           [0009]    The loop of the medical device can have at least two positions, a retracted position wherein the loop is constrained within the lumen of the sheath, and a deployed position wherein the loop is extended beyond the distal portion of the sheath. The deployed position of the medical retrieval device may have a deployed expanded position wherein the loop is expanded and a deployed collapsed position wherein the loop is deployed and collapsed.  
           [0010]    The beads can be manufactured from nitinol, polymers, ceramics, stainless steel, or any combination thereof. The plurality of beads can be made from a material substantially resistant to laser energy. The beads can be sized and configured to be self-aligning when the loop including the beads is pulled taut. In a particular embodiment according to the invention, each of the beads has a lumen and each of the loops of the medical retrieval device include a wire that is slideably moveable within the lumen of each of the beads. An elongated member may be connected to the immovable first end of the loop. In a particular embodiment according to the invention, the medical retrieval device includes two loops and a distal tip that links together the two loops.  
           [0011]    Another aspect of the invention features a system for retrieving material from a body comprising an elongated member having a distal end, a proximal end, and a basket. The basket is disposed at the distal end of the elongated member and has a plurality of N legs formed by N/2 loops. The loops have a first end and a second end. The first end of the loop is fixed, for example, to the distal end of the elongated member, and the second end of the loop is moveable. The loops include a plurality of beads having a lumen with a portion of the plurality of N legs extending therethrough. In a particular embodiment according to the invention, the basket has a retracted position in which the basket is positioned in the lumen of the sheath, a deployed position in which the basket is positioned beyond the distal portion of the sheath and open, and a collapsed position in which the basket is positioned beyond the distal portion of the sheath and the plurality of N legs are collapsed.  
           [0012]    In one embodiment, the system can have a distal tip linking the distal ends of the loops. The beads can be sized and configured to form a basket of predetermined size when the basket is in the extended position. The system can include a handle having a first actuator for moving the basket between the retracted and deployed positions.  
           [0013]    In another aspect, the invention relates to a method for retrieving biological or foreign material from a body, comprising the steps of (a) providing a device which includes (i) an elongated member including a distal end and a proximal end; (ii) a basket disposed at the distal end of the elongated member, the basket having a plurality of N legs formed by N/2 loops; and (iii) a plurality of beads having a lumen with a portion of one of the plurality of N legs extending therethrough defining the loops; (b) inserting the device into the body of a patient; (c) capturing the material with the basket; and (d) withdrawing device from the body to remove the material from the body.  
           [0014]    The step of capturing the material can include capturing a calculus, a kidney stone, a ureteral stone, a bladder stone, or a stone in the biliary tree.  
           [0015]    Another aspect of the invention features a medical retrieval device having a basket including at least one loop including a wire and a plurality of beads, each of the beads further comprising a lumen for slideably receiving the wire of the loop. In a particular embodiment of this aspect of the invention, the wire of the loop may have a first end and a second end, the first end being slideably moveable and the second end being immovable. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0016]    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. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:  
         [0017]    [0017]FIG. 1 illustrates a side view of one embodiment of a medical retrieval device with the basket in open position according to the invention;  
         [0018]    [0018]FIG. 2A illustrates a detailed view of the basket of the medical retrieval device in the deployed position according to one embodiment of the invention;  
         [0019]    [0019]FIG. 2B illustrates a detailed view of the basket of the medical retrieval device in the retracted position according to one embodiment of the invention;  
         [0020]    [0020]FIG. 2C illustrates a detailed view of the basket of the medical retrieval device in the deployed and collapsed position according to one embodiment of the invention;  
         [0021]    [0021]FIG. 3 illustrates a detailed view of the basket tip and the interface with the basket beads according to one embodiment of the invention;  
         [0022]    [0022]FIG. 4A to  4 D illustrate detailed views of the basket tip located at the distal end of the medical retrieval device according to one embodiment of the invention;  
         [0023]    [0023]FIGS. 5A to  5 C illustrate detailed views of the bead elements of the basket located at the distal end of the medical retrieval device according to one embodiment of the invention;  
         [0024]    [0024]FIG. 6A illustrates a perspective view of one of the bead elements of the distal end of the medical retrieval device according to one embodiment of the invention;  
         [0025]    [0025]FIG. 6B illustrates a side view of one of the bead elements of the distal end of the medical retrieval device according to one embodiment of the invention;  
         [0026]    [0026]FIG. 6C illustrates an end view of one of the bead elements of the distal end of the medical retrieval device according to one embodiment of the invention;  
         [0027]    [0027]FIG. 6D illustrates a side view of two bead elements in a loose configuration;  
         [0028]    [0028]FIG. 6E illustrates a side view of two bead elements in coupled configuration;  
         [0029]    [0029]FIG. 7A illustrates a side view of the actuator located at the proximal end of the medical retrieval device according to one embodiment of the invention;  
         [0030]    [0030]FIG. 7B illustrates a side view of the medical retrieval device in a clinical application with the basket in the retracted position according to one embodiment of the invention;  
         [0031]    [0031]FIG. 7C illustrates a side view of the medical retrieval device in a clinical application with the basket in the deployed position and coupling a calculus, according to one embodiment of the invention;  
         [0032]    [0032]FIG. 7D illustrates a side view of the medical retrieval device in a clinical application with the basket in the deployed and collapsed position and releasing a calculus, according to one embodiment of the invention.  
         [0033]    [0033]FIG. 8A illustrates a detailed view of one embodiment of the actuator at the proximal end of the medical retrieval device according to one embodiment of the invention; and  
         [0034]    [0034]FIG. 8B illustrates a detailed view of another embodiment of the actuator at the proximal end of the medical retrieval device according to one embodiment of the invention. 
     
    
     DESCRIPTION  
       [0035]    The embodiments described herein have features in common including a retrieval basket having at least one loop having a plurality of beads, which in a proper configuration form the basic shape of the basket. The retrieval basket of the invention is used to retrieve one or more stones and/or other calculi, objects, or other material from a body tract such as biliary and pancreatic ducts, hepatic ducts, cystic duct, common bile duct, ureters, urinary bladder, urethra, renal pelvis, and kidney.  
         [0036]    Referring to FIG. 1, one embodiment of the retrieval device  10  is shown according to the invention. The retrieval device  10  includes a distal portion  15 , a proximal portion  20 , and an intermediate portion  25  therebetween. A basket  30  is located at the distal portion  15 , an elongated member  35  extends along the intermediate portion  25 , and a proximal handle  45  is located at the proximal portion  20 . The elongated member  35  is joined to a basket base  44  at the distal end of the elongated member  35 , and to the handle  45  at the proximal end of the elongated member  35 . In one embodiment of the invention, the elongated member  35  includes a central lumen  40  longitudinally disposed in the elongated member  35 . A sheath  37  defining a lumen  39  extends from the handle  45  to the distal portion  15  of the retrieval device  10 .  
         [0037]    Referring now to FIG. 2A, the elongated member  35  is longitudinally disposed and slideably moveable in the lumen  39  of the sheath  37 . Sheath  37  is preferably made of commonly available materials which provide sufficient strength and flexibility for adequate operation, but which are soft enough to avoid trauma or irritation to the body lumen in which the sheath  37  is deployed. Materials which may be used to form the sheath  37  include biocompatible polyethylenes, nylons, PEBAX (Ato Chimie Corporation, Allee des Vosges Courbevoie, France), TEFLON (E. I. du Pont de Nemours and Company, Wilmington, Del.), urethane, silicones, other suitable polymer materials, and combinations of the aforementioned materials.  
         [0038]    Referring again to FIG. 1, in one embodiment, the proximal handle  45  includes a first actuator  47  and a second actuator  49 . At least one of the actuators  47 ,  49  is disposed within the proximal handle  45  and connected to one or more basket connecting lines  50 . The one or more basket connecting lines  50  are disposed and slideably moveable in the lumen  39  of the sheath  37  or, alternatively, in the lumen  40  of the elongated member  35 .  
         [0039]    In one embodiment, with continued reference to FIG. 2A, basket connecting lines  50  are slideably moveable within the central lumen  40  of the elongated member  35 . The basket conntecting lines  50  are attached to the basket  30  at the distal portion  15  and are attached to the proximal handle  45  (not shown) at the proximal portion  20 . The basket  30  includes a basket tip  55  at a distal end and the basket base  43  at a proximal end of the basket  30 . A cuff  44  is disposed around the basket base  43 .  
         [0040]    The basket  30  is slideably positionable relative to a distal end  99  of the sheath  37 . For example, in one embodiment according to the invention, the basket  30  can be fixed in a stationary position with the sheath  37  operably joined to one of the actuators  47 ,  49  and slideably moveable in a first direction to deploy and open the basket  30  as illustrated in FIG. 2A, and in a second direction to retract and constrain the basket  30  within the lumen  39  of the sheath  37  as illustrated in FIG. 2B. In an alternative embodiment, the sheath  37  is in a fixed position and the elongated member  35  is operably joined to one of the actuators  47 ,  49  and is slideably moveable in a first direction within the lumen  39  of the sheath  37  to deploy and open the basket  30  and in a second direction to cover and collapse the basket  30  within the lumen  39  of the sheath  37 .  
         [0041]    With renewed reference to FIG. 2A, the basket  30  further includes one or more loops  65  which extend between the basket tip  55  and the basket base  43  to form the shape of the basket  30 . The basket base  43  is disposed at the distal end of the elongated member  35 . The basket tip  55  and the basket base  43  define the respective distal and proximal portions of the basket  30 . In one embodiment according to the invention, the basket is defined by a plurality of legs  77  formed by the loops  65 . For N legs  77 , there are N/2 loops  65 . For example, a basket  30  having two legs  77  contains one loop  65 , a basket  30  having four legs  77  contains two loops  65 , a basket  30  having six legs  77  contains three loops  65 , and so on. Other configurations of the basket  30  are contemplated by the invention.  
         [0042]    With continued reference to FIG. 2A in one embodiment according to the invention, the basket base  43  has a plurality of lumens  62   a ,  62   b . Alternatively, the basket base  43  may have only one lumen  62 . Each loop  65  includes a plurality of beads  70  each bead having a lumen  73 . The beads  70  are strung together along a wire  74  extending through the lumen  73  disposed in each of the beads  70 . A first end  75  of the wire  74  is disposed through a lumen  62   a  of the basket base  43  and attached at a wire attachment point  80 , or alternatively attached to the distal end of the elongated member  35 .  
         [0043]    Referring still to FIG. 2A in one embodiment according to the invention, the basket base  43  includes a cuff  44  through which the wire  74  passes. The basket cuff  44  is interposed between the basket base  43  and the beads  70 . A second end  76  of the wire  74  is slideably disposed through a lumen  62   b  of the basket base  43  and is attached to the distal end  78  of the basket connecting line  50 . The lumen  62   b  of the basket base  43  is sized with a diameter large enough to allow slideable movement of the second end of the wire  76  and yet small enough to prevent passage of the beads  70  through the basket base  43  (and basket cuff  44 , if so included). Accordingly, when tension is applied to the basket connecting line  50  to make the basket connecting line  50  taut, the beads  70  of the loop  65  are compressed together along the wire  74  and against the basket base  43  and the basket shape is formed as shown in FIG. 2A. When the connecting line  50  is released to relax the connecting line  50 , the beads  70  separate from one another and the basket  30  collapsed as illustrated in FIG. 2C.  
         [0044]    Referring now to FIG. 3, the distal end of the basket  30  includes one or more wires  74  that are threaded through the basket tip  55  and the lumen  73  of each of the plurality of beads  70  to form the loops  65  that make the basket  30 . In one embodiment, for example, shown in FIGS. 4A and 4B, the wire  74  extends through wire aperture  81  disposed through a proximal portion  82  of the basket tip  55 . As shown in FIG. 4B, a distal portion  83  of the basket tip  55  is tapered or frusto-conical in shape to provide atraumatic passage through a body lumen. Referring to FIG. 4C, in one embodiment according to the invention, the basket tip  55  may have a plurality of apertures  81  to receive one or more wires  74 . Referring to FIG. 4B in one embodiment, for example, four wire apertures  81  may be disposed within the basket tip  55 . This arrangement of apertures  81  is suitable for two wires  74  (a pair of apertures for each wire  74 ). Three or more wires  74  are also contemplated, requiring six of more wire apertures  81 , accordingly. The basket tip  55  can be shaped to provide ease of insertion and passage through a body lumen. The portion of the basket tip  55  interfacing with the other beads  70  of the loops  65  (FIG. 4A) can be shaped to modify the basket shape when the connecting line  50  and wire  74  is pulled taut as illustrated in FIG. 2A.  
         [0045]    In one embodiment, the beads  70  are made of a thermoplastic, polymeric or ceramic material that is substantially resistant to holmium laser energy. Alternatively, the beads  70  can be made of a metal such as nitinol, stainless steel, or any combination of the aforementioned materials. The wire  74  can be made from a suture material. In one preferred embodiment, the wire  74  is a nitinol core with a polytetrafluoroethylene (PTFE) outer coating.  
         [0046]    Referring now to FIGS. 5A-5C, the beads  70  of the loop  65  can be formed into specific shapes, particularly at the mating surfaces  71  between the beads  70 , so that the beads are self-aligning in that the shape of the basket  30  is formed when tension is applied to the connecting line  50  and the wire  74  that runs through the lumen  73  of each of the beads  70 . The beads  70  of the device  10  are each any suitable pierced member for forming the basket  30 . The beads may comprise a variety of shapes, including, for example, cylindrical, spherical, ellipsoidal, toroidal, parallelapipedal, and cubical.  
         [0047]    Referring to FIG. 5A, in one particular embodiment, the profile geometry of the basket  30  may include beads  70  of the loop  65  having mating surfaces  71  that are canted at various angles to form a basket  30  of desired configuration. In one particular embodiment, two kinds of beads  70  are used: a 9-degree bead whereby the mating surfaces  71  at each end of the bead  70  is canted 9 degrees from the vertical as shown in FIG. 5B; and an 11-degree bead whereby the mating surfaces  71  at each end of the bead  70  is canted 11 degrees from the vertical as shown in FIG. 5C. The beads  70  may be canted at other angles at one or both ends of the bead  70  and/or the bead  70  may also be curved along the longitudinal axis of the bead  70  (not shown). For example, the radii of the basket  30  defining the configuration illustrated in FIG. 5A, is shown with R1 equal to measured 0.3130 inches, R2 equal to 0.3645 inches, and R3 equal to 0.2097 inches. The distance, D from the basket base equals 0.2953 inches. Other basket configurations and dimensions including other radii are contemplated by the invention.  
         [0048]    The beads  70  can also include surface characteristics for specific applications. For example, in one embodiment, the beads  70  can be textured to enhance the material gripping properties. All or a portion of the surface of any of the beads  70  can be roughened by a variety of means including, but not limited to, applying a material coating, forming teeth or ribs on the bead surface, or etching the bead surface.  
         [0049]    Referring to FIGS. 6A and 6B, the diameter of the lumen  73  of the beads  70  is sized at least with a diameter sufficient to allow the wire  74  to slideably move through the lumen  73 . As shown in FIGS. 6C-6E in one embodiment, the mating surfaces  71  may be angled to effect the shape of the basket  30  when the wire  74  is pulled taut. In other embodiments, the mating surfaces  71  of the beads  70  can be adapted for specific use or application to modify the basket into other desired shapes when tension is applied to the wire  74 .  
         [0050]    Referring now to FIG. 7A, in one embodiment, the first actuator  47  is similar to the actuator described in U.S. Pat. No. 5,944,728, co-owned with the present application, the entire contents of which are hereby incorporated by reference. Slideably moving the first actuator  47  in a distal direction towards the distal end of the sheath  37  indicated by arrow  91  (FIG. 7B) causes the sheath  37  to cover and constrain the basket  30  within the sheath lumen  39  as shown in FIG. 7B. Conversely, slideably moving the first actuator  47  in a proximal direction towards the operator indicated by arrow  92  (FIG. 7C) causes the sheath  37  to retract from the basket  30  as shown in FIG. 7C. The loops  65  of the basket  30  are biased in an outwardly radial direction such that the loops  65  spring outward when the sheath  37  is withdrawn from the basket  30  deploying the basket  30  from the distal end  99  of the sheath  37 , the loops  65  assuming an arcuate shape, thereby forming basket  30  as shown in FIG. 7C.  
         [0051]    Once the first actuator  47  positions the basket  30  in the deployed and opened position illustrated in FIG. 7C, the second actuator  49  can collapse the basket  30  as illustrated in FIG. 7D, without retracting the basket  30  into the sheath  37 .  
         [0052]    Referring to FIG. 8A, a sectional view of the second actuator  49 , identified by area B of FIG. 7A is depicted. The second actuator is disposed within the proximal handle  45 . In the embodiment shown in FIG. 8A, the second actuator  49  includes a thumb button  100  slideably disposed and retained by an outer cap  105 . The outer cap  105  is affixed to the proximal end of the proximal handle  45 . The thumb button  100  slides within the retaining slots  110  of the outer cap  105 . The thumb button  100  is biased in a proximal direction by a spring tensioner  115 , the spring tensioner  115  is disposed between a spring plate  120  and the thumb button  100 . One or more basket connecting lines  50  extend from the basket  30  at the distal portion  15  of the device  10  through the central lumen  40  of the elongated member  35 , or, alternatively, through the lumen  39  of the sheath  37 , through the proximal handle  45 , and through the spring tensioner  115  for attachment to the thumb button  100 .  
         [0053]    Referring still to FIG. 8A, pushing the thumb button  100  compresses the spring tensioner  115  between the button  100  and the spring plate  120  and moves the basket connecting line  50  in a distal direction to substantially reduce the tension in the wire  74  of each of the loops  65  in the basket  30 . This, in turn, collapses the basket  30  as illustrated in FIG. 8C, and permits release of captured material. This release capability is applicable in instances requiring immediate and unexpected removal of the device  10  from the body. Releasing the thumb button  100  permits the spring tensioner  115  to restore tension to the basket connecting line  50 , the wire  74 , and the loops  65 , thereby re-forming the expanded basket shape of the basket  30  as illustrated in FIG. 7C. Although only a single basket connecting line  50  is shown in FIG. 7C for clarity, multiple connection lines  50  corresponding to multiple loops  65  of the basket  30  are contemplated.  
         [0054]    In an alternative embodiment, the second actuator  49  can be configured as shown in FIG. 8B. A thumb button  100 ′ is disposed through an outer cap  155  and is coupled to an inner spool  160 . The inner spool  160  is slideably disposed within the outer cap  155 , and engages an actuator cam  157  attached to outer cap  155 . The inner spool  160  is affixed to the outer cap  155 , therefore rotating the outer cap  155  causes rotation of the inner spool  160 . The inner spool  160  is biased in a proximal direction by a spring tensioner  165 . The spring tensioner  165  is longitudinally compressed between a mandrel  169  and the inner spool  160 . The basket connecting line  50  is threaded through a bore in the mandrel  170 , the spring tensioner  165 , and around the inner spool  160  and finally the connecting line  50  terminates at the wire attachment point  175  disposed on the inner spool  160 . Depressing the thumb button  150  compresses the spring tensioner  165  between the mandrel  169  and the inner spool  160 , and moves the basket connecting line  50  in a distal direction to substantially reduce the tension in the wire  74  of each of the loops  65  in the basket  30 . This in turn collapses the basket  30  and permits the release of the captured material. Fully depressing the thumb button  150  causes the inner spool  160  to engage the actuator cam  157  and releasably lock the thumb button  150  in the depressed position and the basket  30  in the open and collapsed position.  
         [0055]    With the thumb button  150  locked in the depressed position, the operator can rotate the outer cap  155  in a first direction, thereby rotating the inner spool  160  in a first direction. The rotation of the inner spool  160  winds the basket connecting line  50  onto the inner spool  160  and advances the connecting line  50  in a proximal direction to increase the compressive force of the basket  30 . This allows the operator to set a threshold retention force for retaining the captured material or to apply sufficient force to the material captured within the basket  30  for fragmentation of the stone. The operator can rotate the outer cap  155  in a second direction, opposite the first direction, which in turn rotates the inner spool  160  in an opposite direction and unwinds the basket connecting line  50  from the inner spool  160 . This advanced the connecting line  50  in a distal direction and allows the basket  30  to collapse and open. With this arrangement, the second actuator  49  can be locked at one or more positions to secure the basket  30  in an open state, a closed state, or various positions therebetween in one of two ways. This configurations allows the operator to tighten the basket connecting lines  50  with varying force, permitting the operator to selectively set the compressive strength of the basket  30  for retrieving and retaining material from the body.  
         [0056]    As shown in FIG. 7B, an operator (e.g., a physician) introduces the device  10  into a body tract  180  of the patient with the basket  30  retracted into the lumen  39  of the sheath  37  at its distal end  99  to achieve the retracted position. In one embodiment, the operator can then position the distal portion  15  of the retrieval device  10  proximate to the material to be retrieved such as, for example, a kidney stone, a ureteral stone, urethral stone, a bladder stone, a gallbladder stone, cholelith, or bile duct stone. As schematically depicted in FIG. 7C, the operator moves the first actuator  47  in the direction of the arrow  92  to withdraw the sheath  37  from the basket  30  to fully deploy the basket  30  from the lumen  39  of the sheath  37  into a deployed expanded position. With the basket  30  fully deployed from the lumen  39 , the basket loops  65  extend radially and the basket  30  becomes sized and configured into a shape, for example, as illustrated in FIG. 7C, that can be manipulated over the material to be retrieved (e.g., a calculus  200 ).  
         [0057]    Referring to FIG. 7C, once the operator positions the basket loops  65  generally around the material, the material can be captured within the basket  30  for subsequent removal from the body or the operator can readily release the material should the anatomical environment require it. By now advancing the sheath  37  over the basket  30  in the direction of the arrow  91  (FIG. 7B), the device may also serve as a mechanical lithotripsy system for crushing or fragmenting stones that are too large to removed intact from the body tract  180  by compressing the stone within the basket  30 .  
         [0058]    A situation can arise during the course of a clinical procedure performed by the operator where ready release of the captured material from the basket  30  is required to permit removal of the device  10  from the patient. Referring now to FIG. 7D, in one embodiment, after capture of the material in the body and while the basket  30  is in the deployed expanded position extending from the end of the sheath  37 , the captured material (such as calculus  200 ) can be released from the basket  30 , by depressing the thumb button  100  of the second actuator  49  to rapidly release tension from the basket connecting lines  50  thereby collapsing the basket  30  into a deployed collapsed position and releasing the material disposed within the basket  30 . To restore the loops  65  to the previous radially outward position (illustrated in FIG. 7C, the operator releases the thumb button  100  thereby returning tension to the basket connecting lines  50  and the wire  74  of the loops  65 . Accordingly, referring again to FIG. 2A, the beads  75  strung along the wire  74  of each loop  65  are compressed together between the basket tip  55  and the basket cuff  44  of the basket  30 . The mating surfaces  71  of the beads  75  are configured to from a basket  30  having a predetermined size and shape.  
         [0059]    In general, the basket, elongated member  35 , and proximal handle  45  are not necessarily shown in their correct size or proportion to each other. The size of the basket  30  and elongated member  35  are dimensioned for the application of the retrieval device in the body. For example, for most biliary type applications, the total working length of the distal portion  15  and the intermediate portion  25  ranges from about 60 inches (150 cm) to about 120 inches (300 cm), and preferably about 71 inches (180 cm). In one embodiment, the size of the basket  30  and elongated member  35  are dimensioned for use within a 3.2 mm or larger diameter working channel of an endoscope. In one embodiment, the length of the beads  70  ranges from 0.040 inches (1 mm) to 0.197 inches (5 mm), the outer diameter of the beads  70  can range from 0.006 inches (0.152 mm) to 0.015 inches (0.381 mm), and the inner diameter of the beads  70  can range from 0.004 inches (0.102 mm) to 0.006 inches (0.152 mm).  
         [0060]    The invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, it must be expressly understood that the foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.