Patent Publication Number: US-10772638-B2

Title: Occluding device and method of manufacturing occluding devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 14/886,461, filed Oct. 19, 2015, which is a divisional application U.S. patent Ser. No. 13/799,591, filed Mar. 13, 2013, now U.S. Pat. No. 9,192,389, the entire contents of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to medical devices. More particularly, the invention relates to occluding devices and methods of manufacturing occluding devices. 
     BACKGROUND 
     Fibered coils have been used as a primary occluding device for treatment of various arteriovenous malformations (AVM) and varicoceles, as well as for many other arteriovenous abnormalities in the body. Occluding devices are also used to repair abnormal shunts between arteries and veins, prevent or reduce blood flow to tumors, stop hemorrhaging as a result of trauma, and stabilize aneurysms to prevent rupture. Pushable and fluid-deliverable fibered coils may be configured in a variety of sizes with varying diameters and may be made of several different materials including stainless steel and platinum. 
     Some fibered coils have strands of fiber wedged between the coil windings. Upon deployment in a body vessel for occlusion, such coils are bent, thus locally increasing the space between the coil windings. 
     SUMMARY 
     The present invention provides an improved occluding device and an improved method of manufacturing such an occluding device. 
     According to a first aspect of the invention, an occluding device for occlusion of fluid flow through a lumen of a body vessel comprises a primary coil having primary coil windings forming a primary coil body with an outer primary coil radius and a primary coil lumen; and fibers attached to the primary coil, the fibers having a length extending generally radially across the primary coil body between the primary coil windings and outward therefrom, the fibers being blocked from slipping along their length relative to the coil body by an adhesive adhering to the fibers inside the primary coil lumen, the adhesive extending radially outward from the coil lumen no farther than the outer primary coil radius. Thus, the fibers are secured inside the primary coil windings without increasing the diameter of the primary coil during delivery. 
     According to one embodiment of the invention, the adhesive is made of a material that does not form a bond with the primary coil windings. The thus chosen adhesive locks the fibers inside the primary coil without affecting the flexibility of the primary coil. Alternatively or additionally, the adhesive may be made of a durably elastic material. 
     According to another embodiment of the invention, the adhesive may joins a plurality of fiber strands into a fiber bundle. Out of the plurality of fiber strands, two or more fiber strands may extend across the primary coil body between different primary coil windings, thus providing an additional safeguard against dislodging of fiber strands. Even if the primary coil were to break in one location, the fiber bundle would still be secured by the fiber strands extending between different coil windings. 
     According to a further aspect of the invention, the adhesive may thicken the fibers inside the primary coil lumen to a thickness greater than a distance between adjacent primary coil windings and thereby lock the fibers relative to the primary coil. Preferably, the thickness is greater than the distance between adjacent coil windings when the primary coil is in a bent configuration. For example, if the primary coil has a relaxed shape that is curled into a secondary coil with a series of secondary loops, the thickness of the adhesive-thickened fibers is preferably greater than the distance between the adjacent coil windings when the primary coil is in its relaxed shape. 
     According to yet another aspect of the invention, the adhesive is made of a material that forms bonds with both the fibers and the primary coil windings. Preferably, the adhesive material is then chosen from durably elastic materials. 
     According to one aspect of the invention, an occluding device for occlusion of fluid flow through a lumen of a body vessel is manufactured by a method comprising the steps of providing a primary coil having primary coil windings forming a primary coil body with an outer primary coil radius and a primary coil lumen; wedging fibers between adjacent coil windings so that the fibers extend generally radially across the primary coil body between the primary coil windings and outward therefrom; distally inserting an elongated adhesive applicator into the primary coil lumen; proximally withdrawing the adhesive applicator while simultaneously depositing along the primary coil windings; and wherein the fibers and the adhesive are placed in overlapping locations so that the fibers extend through the adhesive. In the course of performing the method, the fibers may be wedged between the adjacent coil windings before the adhesive is deposited, or afterwards. 
     In one embodiment of the invention, the elongated adhesive applicator is a wire guide. 
     According to a further aspect of the invention, the wire guide may be hollow with a longitudinal channel extending from a proximal end to at least one opening near a distal end. For example, the at least one opening may be formed by two radial openings opposite each other. 
     According to yet another aspect of the invention, the at least one opening may be proximally adjacent to a tapered or rounded distal tip. Preferably, the tapered or rounded distal tip has a length of at most about 1 cm. 
     According to an alternative aspect of the invention, the elongated adhesive applicator has an outer surface, and the method comprises the further step of applying adhesive to the outer surface prior to inserting the adhesive applicator into the primary coil lumen. 
     Further details and benefits of the invention become apparent from the following description of various embodiments shown in the attached drawings. The drawings are provided for purely illustrative purposes and are not intended to limit the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         FIG. 1 a    is a side view of an occluding device in accordance with one embodiment of the present invention; 
         FIG. 1 b    is a cross-sectional view of the occluding device of  FIG. 1 a    taken along line  1   b - 1   b;    
         FIG. 2 a    is a side view of a primary coil in  FIG. 1  depicting the occluding device in an uncoiled length; 
         FIG. 2 b    is a cross-sectional view of the primary coil in  FIG. 2   a;    
         FIG. 3 a    illustrates a first step of a first embodiment of a method of assembling the occluding device of  FIG. 2 ; 
         FIG. 3 b    illustrates a second step of the method of  FIG. 3   a;    
         FIG. 3 c    illustrates a third step of the method of  FIGS. 3 a    and  3   b;    
         FIG. 3 d    illustrates a fourth step of the method of  FIGS. 3 a    through  3   c;    
         FIG. 4 a    illustrates a first step of a second embodiment of a method of assembling the occluding device of  FIG. 2 ; 
         FIG. 4 b    illustrates a second step of the method of  FIG. 4   a;    
         FIG. 4 c    illustrates a third step of the method of  FIGS. 4 a    and  4   b;    
         FIG. 5 a    is a cross-sectional view of the occluding device of  FIG. 1 a    taken along line  5   a - 5   a;    
         FIG. 5 b    is an enlarged view of the occluding device in area  5   b  of  FIG. 1 a   ; and 
         FIG. 6  is an exploded view of an embolization kit for one embodiment of the occluding device of the present invention; 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The following provides a detailed description of currently preferred embodiments of the present invention. The description is not intended to limit the invention in any manner, but rather serves to enable those skilled in the art to make and use the invention. 
     The present invention generally provides an occluding device used for transcatheter embolization. The occluding device is preferably used to occlude fluid flow through a lumen of a body vessel such as for an occlusion of an arteriovenous malformation (AVM). The occluding device comprises a primary coil having a relatively low initial tension. The primary coil may be formed in a helical shape to define a secondary coil. Preferably, the primary coil  11  assumes the shape of the secondary coil  12  in a relaxed state, i.e. without the influence of any external forces. The occluding device may be made of any material suitable for occluding devices that is preferably detectable with customary imaging methods, for example platinum for its radiopacity. 
     The occluding device preferably includes fibers wedged or attached between loops of the primary coil and extending therefrom. When the occluding device is deployed in a lumen of a body vessel, the fibers help to occlude fluid flow through the lumen of the body vessel. 
     The occluding device also may be used for treatment of renal AVM, pulmonary AVM, vascular tumors, low-flow fistulas, trauma related hemorrhages, and visceral vasculature defects including varicoceles, aneurysms, and selected telangiectasias. For example, treatment of visceral vasculature defects may include but are not limited to embolotherapy on gastroduodenal hemorrhages, hepatic aneurysms, celiac aneurysms, internal iliac aneurysms, and internal spermatic varicoceles. 
       FIG. 1 a    illustrates an occluding device  10  for occlusion of fluid flow through a lumen of a body vessel in accordance with one embodiment of the present invention. The occluding device shown in  FIGS. 1 a  through 2 b , 5 a , and 5 b    comprises a primary coil  11  formed in a secondary coil  12 . The primary coil  11  is formed to define a primary body  13  defined by primary windings  19  that are arranged adjacent to each other with minimal spacing and that surround a primary lumen  15 . The primary body  13  may be further shaped by a coil winding machine into a helical shape to define a secondary coil  12 . The secondary coil  12  includes a series of secondary loops  20  of a secondary body  14  having a first end  16  and a second end  18 . The series of secondary loops  20  define a cross-sectional lumen formed axially along the secondary coil  12  as seen in  FIG. 5 a   . Preferably, the occluding device  10  further includes fibers  24  attached to the primary windings  19  of the primary coil  11 . 
     Preferably, the primary coil  11  comprises platinum or any other suitable metal, composition, or alloy having between about 50,000 and 350,000 pounds per square inch tensile strength. It has been determined that the tensile strength range described above provides the coil with the capability of being flexible, malleable, and folded. 
     The primary coil  11  may be made by any apparatus known in the art. For example, the coil may be made by any commercial coil winding machine such as a roller deflecting apparatus, a mandrel apparatus, or any other suitable means. 
     In this embodiment, the primary coil  11  may have a length of between about 3 to 20 centimeters. As shown in  FIG. 5 a   , the secondary coil  12  may have an outer diameter ranging between about 3 and 45 millimeters. For most applications, the outer diameter will not exceed about 25 millimeters. The primary coil  11  may have an outer diameter of between about 0.010 and 0.04 inch. The catheter inner diameter through which the occlusion device may be advanced ranges between about 0.014 and 0.045 inch, depending on the outer diameter of the primary coil  11 . 
       FIGS. 1 and 5   b  illustrate the helical body  14  of the secondary coil  12  having a series of connected secondary loops  20  axially spaced apart by a predetermined distance. In this embodiment, the predetermined distance of up to 4 millimeters curl space. Curl space is defined as the distance between two secondary loops  20  of secondary coil  12 . 
     As shown in  FIGS. 1 and 2 , the fibers  24  of the occluding device  10  are attached to the primary coil  11  and extend therefrom. The fibers  24  are spaced apart from each other and are held between the primary windings  19  of the primary coil  11 . The fibers  24  include strands  28  made of a synthetic polymer such as a polyester textile fiber, e.g., DACRON™. As desired, the strands may be wedged between alternating primary windings  19 , alternating double primary windings  19 , or any desired configuration. The strands  28  being held spaced apart from each other along the extended length of the primary coil  11 , e.g., 14 centimeters, avoid an enlarged diameter created when fibers  24  fold or bend over each other when the primary coil  11  is loaded in a catheter. As a result, an undesirable resistance is avoided when the primary coil  11  is advanced through the catheter. 
     Preferably, the strands  28  have a length extending generally radially across the primary body  13  between the primary windings  19  and outward from the primary coil  11 . The length of the fibers  24  ranges between about 3 and about 8 millimeters. In an application the strands may be between about 5 to 6 millimeters long as desired. In this embodiment, the fibers  24  are spaced apart from each other by about 1 to 3 millimeters. Preferably, the strands  28  have an outer diameter of about 0.0005 to 0.002 inch. 
     As shown in  FIG. 1 b    and, in more detail, in  FIG. 2 b   , the fibers  24  are blocked from slipping out of the primary body  13  along their length by an adhesive  30  adhering to the fibers inside the primary coil lumen. In the shown embodiments, the adhesive  30  forms beads  32  around the fibers  24 . The adhesive  30  is generally located inside the lumen  15  of the primary coil  15 . Small amounts of the adhesive  30  may extend between the primary coil windings, but an improved method of manufacturing the occluding device  10  described below ensures that the adhesive generally does not extend farther outward than the outer diameter d of the primary coil  11 . Thus, the adhesive does not enlarge the diameter of the occluding device  10  and does not impede the delivery of the primary coil  11  through a catheter or a syringe. 
       FIG. 2 b    shows the adhesive beads  32  in two locations along the length of each of the fibers  24 . The two locations are those inside the lumen  15  of the primary coil  11  that are adjacent to the primary windings  19 . The adhesive  30  may have a high surface tension that promotes beading around the fibers  24 . Alternatively, the adhesive may only be applied to one location along each fiber  24  or along the entire portion of the fiber that extends inside the primary lumen  15 . 
     In one embodiment of the invention, the adhesive  30  is made of a material that does not form a bond with the preferably metallic primary windings  19 , but with the material of the fibers  24 . Preferably, the adhesive  30  is applied in a low-viscosity state that obtains a higher viscosity after the fibers  24  have been inserted between the primary windings  19 . For example, the material of the adhesive  20  and of the fibers  24  may be chosen to promote cross-linking during a drying or curing process. The curing process may be facilitated by heat, light, or a chemical process over time. Alternatively, the adhesive  30  may be made of a material that forms bonds with both the fibers  24  and the primary coil windings  19 . 
     The adhesive  30  may further be made of a durably elastic material, for example silicone. Due to the elasticity, the adhesive  30  resists breakage and chipping when the primary coil  11  is deformed before and after implantation in a body vessel. Especially if the adhesive  30  also bonds with the primary windings  19 , it is also preferable that the adhesive  30  retains some elasticity to compensate for movements of the primary coil windings  19  relative to each other while the primary coil  11  is loaded into a catheter or syringe and during implantation. 
     As shown in  FIG. 2 b   , the adhesive  30  may join a plurality of fiber strands  28  into a fiber bundle  34 . While  FIG. 2 b    shows fiber bundles  34  with fiber strands  28  that all extend between the same primary windings  19 , alternatively, different fiber strands  28  of the same fiber bundle  35  may also extend outward between different primary windings  19  so that the fiber bundle  35  may, for example, be bifurcated or trifurcated through the primary windings  19 . Larger beads  33  of adhesive may be formed to adhere to the strands  28  of the split fiber bundle  35 . Although only one of the split fiber bundles  35  is shown in  FIG. 2 b   , several or all fiber bundles of the occluding device may be split among primary windings  19 . Thus, even if the primary coil  11  were to be damaged in one location, the fiber bundle  35  would still be secured by fiber strands  28  extending between primary windings  19  unaffected by the damage. 
     Preferably, the adhesive thickens the fibers  24  inside the primary coil lumen  15  to a thickness that is greater than the distance between the adjacent primary coil windings  19 . While the primary coil  11  is usually tightly wound so that no or only minimal spaces are present between the primary windings  19  when the primary coil  11  is straightened absent an expanding force, the spaces increase when the primary coil  11  is curled into the secondary coil  12  or when the primary coil  11  is bent during implantation in the body vessel. Preferably, the adhesive, in the form of the beads  32  or other shapes, thickens the fibers to a thickness that amounts to at least the space between the primary windings  19  when the primary coil  11  assumes a bent shape, particularly the curled shape of the secondary coil  12 . 
       FIGS. 3 a  through 3 d    illustrate a first example of a method of assembling the occluding device  10 . An elongated adhesive applicator  36  is inserted into the primary coil lumen from one axial side and through the primary lumen  15  to the other coaxial end of the primary coil  11 . For example, the adhesive applicator  36  may be a wire guide  37 . 
     In one embodiment of the invention, the wire guide  37  is hollow with a longitudinal channel  38  extending from a proximal end to openings  40  near a distal end. In the embodiment of  FIG. 3 , two radial openings  40  are provided opposite each other. It is, however well within the scope of the present invention to provide only one opening  40 , for example at the distal end of the wire guide  37 , or more than two openings  40 . The openings may be distributed around the circumference of the wire guide. Also, the openings  40  may be axially offset from each other to allow for larger openings  40  than if all openings  40  were all placed side by side in a single axial location the wire guide. 
     If the opening or openings  40  are radial openings, the wire guide  37  may have a rounded or tapered distal tip  42  facilitating the insertion of the wire guide  37  into the primary coil  11  without damage to the primary windings  19 . In the example shown, the distal tip  42  is rounded, but it may additionally be tapered. The rounded tip may even make it possible to insert the wire guide into the primary coil  11  without first straightening the primary coil  11 . The primary coil  11  can easily slip past the rounded tip  42  without damage or plastic deformation, and the rounded tip reduces the risk that the distal end of the wire guide  37  could get caught on any of the primary windings  19 . 
     The tapered or rounded distal tip  42  does not need to be very long to facilitate threading the primary coil onto the wire guide  37 . The distal tip  42  may have a length of up to about 1 cm. While such a short length of the distal tip  42  is preferred, greater lengths are still within the scope of the present invention. 
     Instead of a hollow adhesive applicator  36 , a solid elongated adhesive applicator may be used for applying the adhesive. 
     Once the adhesive applicator  36  is inserted into the primary lumen  15 , the adhesive applicator  26  is slowly withdrawn while the adhesive  30  is simultaneously applied to the primary coil windings  19  inside the primary lumen  15 . 
     When a solid applicator  36  is used to deposit the adhesive, the adhesive  30  may be applied to the outer surface of the adhesive applicator  36  prior to inserting the adhesive applicator  36  into the primary coil lumen  15 . This method of depositing the adhesive  30  is mostly suited for relatively short primary coils  11  because the adhesive  30  may be depleted over only a short axial distance along the primary coil. To double the axial length, in which the adhesive is deposited, the solid adhesive applicator  36  may also be inserted into the lumen and withdrawn from the opposite end of the primary coil  11 . 
     Especially for longer primary coil  11 , the hollow guide wire  37  as shown in  FIGS. 3 a  through 3 c    is better suited for an even axial distribution of the adhesive  30 . While the guide wire  37  is withdrawn from the primary lumen  15 , the adhesive  30  is pressed from the proximal end of the guide wire  37  through the longitudinal channel and out of the openings  40  onto the inside surfaces of the primary windings  19 . The two radial openings  40  of the shown embodiments created to longitudinal lines of adhesive  30  that are circumferentially offset by about 180°. Thus the adhesive is deposited in two lines extending opposite to each other along the inside of the primary lumen  15 . Alternatively, a single distal opening  40  in the guide wire  37  might be used to substantially fill out the primary lumen  15  with the adhesive  30 , or a greater number of radial openings  40  may be used to create more than two longitudinal lines of adhesive  30  along the inside of the primary lumen  15 . 
     As shown in  FIG. 3 d   , after the adhesive  30  has been deposited inside the primary lumen  15 , the fibers  24  may be wedged between adjacent primary coil windings  19  in angular locations where the adhesive has been deposited. For example, as the lines of adhesive  30  are shown to be located at the top and at the bottom of the primary lumen  15 , the fibers  24  may be inserted in a generally vertical orientation. In  FIG. 3 d   , for example, the fibers may be inserted between two adjacent primary coil windings  19  from behind, i.e. from the background of the drawing toward the foreground of the drawing. As a result, the fibers  24  extend generally radially across the primary body  13  between the primary coil windings  19  and outward therefrom. Because the fibers  24  were inserted between the primary windings  19  in a direction generally perpendicular to the length of the fibers  24 , none of the adhesive  30  comes into contact with any portions of the fibers  24  that extend outward from the primary body  13 . This process ensures that the adhesive remains mostly inside the primary lumen and does not enlarge the outer diameter d of the primary coil  11 . 
     In a second embodiment of the method of assembling the occluding device  10 , the step of  FIG. 3 d    is performed first, before any adhesive is deposited in the primary coil  11 , as illustrated in  FIGS. 4 a  through 4 c   . After all the fibers  24  have been placed in their positions between the primary windings  19  according to  FIG. 4 a   , the adhesive applicator  36  with a preferably tapered tip  42  is inserted into the primary lumen  15 , according to  FIG. 4 b   , and deposits the adhesive  30  in the primary lumen  15 . Because the fibers  24  are already present, the tapered tip  42  has a distal end that is preferably narrow enough to form a path past the fibers  24  and that does not pull the fibers  24  into the primary lumen. Thus, the steps of  FIGS. 4 b  and 4 c    of depositing the adhesive  30  inside the primary lumen  15  may be performed after the step shown in  FIG. 4 a   . In this second embodiment of the method according to  FIG. 4 , the fibers  24  may be pulled lengthwise between the primary windings  19 , i. e. along the length of the fibers  24 , because no adhesive is present inside the primary lumen  15 . Thus, even if a fiber portion is pulled from the inside of the primary lumen  15  to the outside, that portion of the fibers  24  has not come into contact with any of the adhesive  30  yet so that the adhesive  30  does not increase the outer diameter d of the primary coil  11 . As mentioned in connection with the method of  FIG. 3 , this second embodiment may also be performed with an applicator having different arrangements of the openings  40 , such as a single distal or radial opening or a plurality of openings distributed around the circumference that may additionally or alternatively be axially offset from each other. 
     Further, while not shown, it is evident that the adhesive may also be applied in an amount filling out the entire lumen of the primary coil  11  by either one of the methods of  FIGS. 3 and 4 . 
     During deployment of the occluding device  10 , the primary coil  11  may be folded across the lumen of a body vessel to be occluded. When the device  10  is deployed from a catheter, a low inherent tension of the primary coil provides the primary coil the capability of being folded across the lumen of a body vessel for cross-sectional occlusion. In this embodiment, when the primary coil is folded with the strands  28 , the occluding device  10  is in a “packed” or “nested” state a length of about 5% or more of the original length of the primary coil  11  as generally known from the prior art. When packed, the occluding device  10  provides a relatively tightly nested, dense mass that effectively occludes fluid flow though a lumen of a body vessel. 
       FIG. 6  depicts a body vessel embolization kit  110  which implements the occluding device in accordance with one embodiment of the present invention. As shown, the kit  110  includes a microcatheter  114  defining a catheter lumen and preferably made from a soft, flexible material such as silicone or any other suitable material. Generally, the microcatheter  114  has a proximal end  122 , a distal end  124 , and a plastic adapter or hub  116  to receive apparatus to be advanced therethrough. In this embodiment, the inside diameter of the microcatheter  114  may range between 0.014 and 0.027 inch. The kit  110  further includes a guide wire  120  which provides the guide catheter  118  a path during insertion of the guide catheter  118  within a body vessel. The size of the wire guide  120  is based on the inside diameter of the guide catheter  118 . 
     In this embodiment, the guide catheter or sheath  118  of the kit  110  is made of polytetrafluoroethylene (PTFE) for percutaneously introducing the microcatheter  114  in a body vessel. Of course, any other suitable material may be used without falling beyond the scope or spirit of the present invention. The guide catheter  118  may have a size of about 4-French to 8-French and allows the microcatheter  114  to be inserted therethrough to a desired location in the body vessel. The guide catheter  118  receives the microcatheter  114  and provides stability of the microcatheter  114  at a desired location of the body vessel. For example, the guide catheter  118  may stay stationary within a common visceral artery, e.g., a common hepatic artery, and add stability to the microcatheter  114  as the microcatheter is advanced through the guide catheter to a point of occlusion in a connecting artery, e.g., the left or right hepatic artery. 
     When the distal end  124  of the microcatheter  114  is at the point of occlusion in the body vessel, the occluding device is loaded at the proximal end  122  of the microcatheter  114  and is advanced through the microcatheter for deployment through the distal end  124 . In this embodiment, a push wire  126  is used to mechanically advance or push the occluding device through the microcatheter  114 . The size of the push wire used depends on the diameters of the microcatheter. 
     It is to be understood that the body vessel embolization kit  110  described above is merely one example of a kit that may be used to deploy the occluding device in a body vessel. Of course, other kits, assemblies, and systems may be used to deploy any embodiment of the occluding device without falling beyond the scope or spirit of the present invention. 
     The occluding device may be deployed in a body vessel by a push embolization method or a squirt embolization method in accordance with the present invention. 
     While the present invention has been described in terms of preferred embodiments, it will be understood, of course, that the invention is not limited thereto since modifications may be made to those skilled in the art, particularly in light of the foregoing teachings.