referring now to the figures , wherein the components are labeled with like numerals throughout the several figures , and initially to fig1 a and 1 b , one exemplary embodiment of an anastomosis device 10 is illustrated , which includes an elongated catheter shaft 12 having a central drainage lumen 14 that extends generally along the length of catheter shaft 12 . catheter shaft 12 further includes an actuation wire lumen 16 through which an actuation wire for the tissue approximating structure can extend , and an inflation lumen 18 used for inflation and deflation of a balloon near the tip of the device . catheter shaft 12 further includes at least one cable or wire 20 that acts as a reinforcement structure and extends through the wall of catheter shaft 12 along at least part of its length . this cable or wire 20 is made of a material that provides added strength to the device 10 to prevent or minimize stretching or deformation of catheter shaft 12 during manipulation of device 10 and / or to protect the integrity of the device if it is subjected to unanticipated loads , such as impact loads . thus , cable or wire 20 is preferably chosen or designed to be as thin and lightweight as possible so as to not add unnecessary weight or bulk to device 10 , while still providing the desired amount of protection for the device . in addition , cable or wire 20 should be of a size and shape that maintains a relatively flexible catheter shaft 12 for patient comfort . more than one cable or wire 20 may be used in a particular catheter shaft 12 , where multiple wires 20 within a single device may be spaced from each other within the wall of catheter shaft 12 . cable or wire 20 may be coextruded within the wall of catheter shaft 12 , or may instead extend through a central opening of catheter shaft 12 . in a further alternative , cables or wires 20 may be located on the outside of catheter shaft 12 and may be secured to shaft 12 by adhesive mechanical attachment , wrapping of wire 20 about shaft 12 , and the like . cables or wires 20 may be solid lengths of material such as metal , plastic , fabrics , woven materials , and the like , or may instead be hollow tubular structures . each cable or wire 20 may comprise more than one piece of the same or different materials that are woven or otherwise attached to each other along their lengths . fig1 c is a cross - sectional view of a section of wire or cable 22 that may be have a structure as described above relative to fig1 a and 1 b . wire or cable 22 extends through a lumen 24 along at least a portion of a catheter shaft , and may optionally include a ball or enlarged portion 26 at one or both of its ends . this embodiment further includes an adhesive 28 within at least a portion of lumen 24 for securing wire 22 so that it cannot move relative to lumen 24 . if wire 22 includes an enlarged portion 26 , this enlarged portion 26 can provide an anchor point to help prevent movement of wire 22 along the length of the catheter shaft . adhesive 28 may optionally be provided in a color or material that is visible or otherwise detectable to determine the amount of adhesive 28 placed within lumen 24 . in this way , the manufacturer can detect when an adequate amount of adhesive 28 is added to lumen 24 , which can also prevent overflow of adhesive from lumen 24 that may occur with the addition of too much adhesive . fig2 and 3 illustrate a catheter funnel 30 of an anastomosis device that would typically be located at the proximal end of the anastomosis device . this funnel 30 includes an integrated strain relief portion 32 that allows for compression and extension of funnel portion 30 when the device is subjected to external loads . relief portion 32 is illustrated as an accordion - like section of the device between two sections that are generally not expandable or compressible . relief portion 32 may be as long or short as desired , where a longer relief portion 32 will provide additional flexibility to the device . relief portion 32 should have sufficient radial strength to keep it from collapsing on itself or kinking during or after placement within a patient . in addition , relief portion 32 should be long enough that it allows for a normal amount of compression or extension of the device when subjected to loads . relief portion 32 may be a portion of funnel 30 that is an integral to funnel 30 ( e . g ., it is integrally molded or formed with the other portions of funnel 30 ). alternatively , relief portion 32 may be a separate section that is attached at one or both ends to remainder of funnel 30 . further , relief portion 32 may be provided in a different configuration than that shown in order to provide a different flexibility for this portion as compared to the portions on either side of it . for example , relief portion 32 may be configured as an elongated tube that is made of a material that is more flexible or elastic than the areas of funnel 30 to which it is attached , thereby providing the desired strain relief properties to funnel 30 . referring now to fig4 a , a tip portion 40 of an anastomosis device is illustrated , which includes a catheter shaft 42 and a plurality of extending tissue approximating structures or tines 46 . tip portion 40 further includes a connective sheath 44 having two rings of mesh 48 in the general area of the extending tines 46 . rings of mesh 48 are spaced from each other along the length of sheath 44 , and are preferably positioned to include most or all of the areas of sheath 44 through which tines 46 may extend . that is , if the device includes two sets of tines 46 , one ring of mesh 48 is preferably provided for each set of tines 46 , although it is possible that less rings of mesh 48 are provided than the number of sets of tines 46 . mesh 48 adds support to the structure in the areas where the tines extend through sheath 44 and thus may be provided in any area of the anastomosis device through which tines extend ( e . g ., through the catheter shaft if this is the area of the device that includes extending tines ). in this way , the areas of mesh 48 can prevent or minimize tearing or other damage to sheath 44 or catheter body that may occur if it is subjected to certain forces that are placed on the anastomosis device . in addition , mesh 48 can provide sufficient additional structure to the device to prevent sheath 44 from stretching . mesh 48 may be integrated into connective sheath 44 , as shown in fig4 a . alternatively , mesh portions 50 may be overmolded or bonded to a connective sheath , such as to the portion of a connective sheath 52 illustrated in fig4 b . sheaths 44 , 52 may be made of a flexible material , such as silicone , and mesh portions 48 , 50 are preferably made of a relatively lightweight and bendable material , such as metal , plastic , natural or synthetic fibers , or the like . mesh portions 48 , 50 may also have a wide variety of configurations , such as a woven or knitted construction , that allow for relatively easy penetration of any tissue approximating structures . fig5 illustrates another tip portion 60 of an anastomosis device , which includes a catheter shaft 62 and a plurality of extending tissue approximating structures or tines 64 . tip portion 60 further includes a connective sheath 66 having a single elongated area of mesh 68 that extends along the length of sheath 66 for a distance that is long enough to encompass all of the sets of tines 64 that extend from sheath 66 . in this embodiment , mesh 68 extends along the entire length of sheath 66 , which thereby includes both sets of tines 64 . as with the mesh reinforcements provided in fig4 a and 4 b , mesh 68 preferably provides sufficient additional structure to the device to prevent sheath 66 from stretching , and also preferably is strong enough to prevent or minimize tearing or other damage to sheath 66 or catheter body that may occur if it is subjected to certain forces that are placed on the anastomosis device . mesh 68 may either be incorporated into connective sheath 66 or be bonded or overmolded to connective sheath 66 . further , mesh 68 may be provided in any area of the anastomosis device through which tines extend ( e . g ., through the catheter shaft or some other component of the device if this is the area of the device that includes extendible tines ). another tip portion 70 of an anastomosis device is illustrated in fig6 a and 6 b , which includes a catheter shaft 72 and a plurality of extending tissue approximating structures or tines 74 . tip portion 70 further includes a connective sheath 76 having reinforced portions 78 in the area through which tines 74 extend from its outer surface . as shown , reinforced portions 78 may be extending rings of material that are thicker than surrounding sheath 76 . the height , width , and thickness of portions 78 may be similar or different from the illustrated portions 78 , but should preferably provide a desired additional strength to the sheath that helps to prevent or minimize tearing or other damage to sheath 76 in the areas where tines 74 extend through sheath 76 . portions 78 may either be incorporated into the connective sheath 76 or be bonded or overmolded to connective sheath 76 . again , the reinforced portions may be provided in any area of the anastomosis device through which tines extend , such as through the catheter shaft if this is the area of the device that includes extendible tines . fig7 a illustrates a tip portion or assembly 80 of another embodiment of an anastomosis device , which includes a catheter shaft 82 and a connective sheath 84 . tip portion 80 comprises a flexible core 86 ( also illustrated in fig7 b ) configured as an elongated tubular portion 88 with a flanged tip 90 at one end . flanged tip 90 is designed to mate or interlock with an opening 94 of a tip 92 . in this way , force that is exerted on the bottom of a balloon when it is inside the patient will be transmitted along the length of tip assembly 80 and back to catheter shaft 82 . this transmission of force can therefore minimize the forces on the portions of assembly 80 that can include tissue approximating structures or tines , for example . flexible core 86 may be configured with differently sized and shaped tubular portions and flanged tips to provide a similar force transmission . of course , the tip would need to be designed to mate with the portions of the flexible core that would be inserted within it . the anastomosis devices of the invention may further include methods and devices for placing markers on the anastomosis device to facilitate accurate placement of the device within the patient . for one example , tissue approximating structure markers can be used to indicate the location from where the tissue approximating structures expand or extend . these markers could be differentiated visually , such as with color , radiographically , echogenically , or the like . for another example , luminal markers can be used to indicate the locations of the various lumens within a device . these markers could also be differentiated visually , such as with color , radiographically , echogenically , or the like . for another example , directional markers can be used to indicate if and when the tissue approximating structures have been deployed or retracted . these markers could be visual , tactile , audible , or detectable in any other manner . these directional markers can also correspond to the color of other areas of the device , such as the areas where the tine sets are located , so that the user can determine which of multiple sets of tines are deployed or retracted at a given time . a particular anastomosis device may include one or a combination of the structures and devices described above to reinforce or otherwise enhance the flexibility , strength or other properties of a device , as desired . the choices may be made to protect the device from the most likely forces or strains that may occur , thereby preventing or minimizing damage to the anastomosis device and / or injury or discomfort to the patient . in a related embodiment , a surgical tool is disclosed that is adapted to include the strain relief feature described above for connecting external devices to external tissues of a human or animal body . the strain relief features described herein are also applicable to , but not limited to , other external communicating medical devices or tools that may include foley catheters , dialysis ports , venous access devices , and the like . the invention has now been described with reference to several embodiments thereof . the foregoing detailed description and examples have been given for clarity of understanding only . no unnecessary limitations are to be understood therefrom . it will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention .