Abstract:
A catheter assembly for implanting a medical device, comprising a first wire and a second wire, electrically insulated from each other, attached to the medical device at a first attachment point and a second attachment point, respectively. The first wire defines a first region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to a the first attachment point. Similarly, and the second wire defines a second region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to the second attachment point. Also, there is a separately controllable electric supply for the first and the second wire, so that the first wire may be disconnected from the medical device, without disconnecting the second wire.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of application serial number PCT/US12/27259, filed on Mar. 1, 2012 which claims priority from provisional application Ser. No. 61/448,459, filed on Mar. 2, 2011 which are incorporated by reference as if fully set forth herein. 
     
    
     BACKGROUND 
       [0002]    The present disclosure is directed to repairing blood vessel defects, such as aneurysms, and other physiological defects or cavities formed in lumens, tissue, and the like, and, more particularly, to an endovascular implantable device and related endoluminal delivery procedure and deployment techniques. 
         [0003]    Cranial aneurysms occur when a weakened cerebral blood vessel (root vessel) locally expands to form a bulge or balloon-like enlargement in the vessel wall. These aneurysms can occur along a vessel wall or at locations of vessel branches, such as a T-intersection or V-intersection. 
         [0004]    Currently, options for the treatment of brain aneurysms are limited. In one technique, the cranium is opened and a clip is placed at the aneurysm neck to cut off blood flow from the root vessel, thereby reducing swelling and stopping expansion. In another technique, the interior of the aneurysm is accessed by way of a cranial artery, which in turn is reached with a device inserted into the femoral artery. In this technique, coiling material is inserted into the aneurysm, thereby causing clotting which closes off the aneurysm. Both techniques have drawbacks. Opening the cranium always entails some risk. Some locations in the cranium are difficult or impossible to access from the outside. On the other hand, causing clotting in the aneurysm can increase the mass and size of the aneurysm, causing it to press against delicate and critical tissue, and causing further damage. 
         [0005]    Devices and techniques have been developed to facilitate treatment of aneurysms. The application herein is a joint inventor on the following U.S. Patent Publication Nos. 2006/0264905 (“Improved Catheters”), 2006/0264907 (“Catheters Having Stiffening Mechanisms”), 2007/0088387 (“Implantable Aneurysm Closure Systems and Methods”), and 2007/0191884 (“Methods and Systems for Endovascularly Clipping and Repairing Lumen and Tissue Defects”). All of these published applications are incorporated by reference herein in their entirety, to the extent legally possible. 
         [0006]    For example, referring to  FIGS. 1A and 1B , which are reproduced from U.S. Patent Publication No. 2007/0191884, shown therein is a device  130  having a patch or closure structure  131  mounted to or associated with two anchoring structures  132 ,  133 . The closure structure  131  is supported by a framework structure  134  that is provided at least in a perimeter portion and is attached to the closure structure  131  by means of bonding, suturing, or the like. The framework structure  134  is mounted to or associated with the wing-like anchoring structures  132 ,  133 . These anchoring structures  132 ,  133  in a deployed condition are designed so that at least a portion thereof contacts an inner wall of an aneurysm or an internal wall of an associated blood vessel following deployment. 
         [0007]    As can be seen in  FIG. 1A , the anchoring structures  132 ,  133  are generally formed to curve outwardly from an attachment joint  135  to the framework structure  134  and then back inwardly toward one another at the end remote from the attachment point  135 . The anchoring loops  132 ,  133  are generally of the same configuration and same dimension and are located opposite one another as shown in  FIG. 1A . 
         [0008]      FIG. 1B  illustrates a similar device having a closure structure  136  with anchoring structures  137 ,  138  that attach to or project from a framework structure  139  along opposed, lateral edges of the framework structure. The anchoring structures  137 ,  138  as illustrated in  FIG. 1B  are gently curved and, at their terminal sections, extend beyond corresponding terminal sections of the framework structure and the closure structure. The closure and framework structures in this embodiment are generally provided having a surface area that exceeds the surface area of the aneurysm neck, and the anchoring structures generally reside inside the aneurysm following placement of the device. In this configuration, the anchoring structures exert lateral and downward force on the closure structure so that it generally conforms to the profile of the vessel wall at the site of the aneurysm, thereby sealing the neck of the aneurysm from flow in the vessel and providing reconstruction of the vessel wall at the site of the aneurysm. Unfortunately, framework structure  139  and structures  137  and  138  are mismatched in length and are too stiff to apply the mutually opposing forces on interposed tissue, necessary to form an effective clip. In addition this structure is too stiff and expanded to be able to collapse into a configuration that can be fit into the space available in a placement device, small enough to be introduced into the smaller cranial blood vessels. Moreover, its boxy shape makes it difficult to maneuver as is necessary to effect placement into an aneurysm. 
         [0009]      FIGS. 1C-1F  schematically illustrate the devices of  FIGS. 1A and 1B  deployed at the site of an aneurysm. A bulge in the blood vessel B forms an aneurysm A. As shown in  FIGS. 1C and 1D , when the device  130  is deployed across the neck of and within the aneurysm A, the closure structure  131  is positioned to cover the opening of the aneurysm and the anchoring structures  132  and  133  are retained inside and contact an inner aneurysm wall along at least a portion of their surface area. In this fashion, the closure structure  131  and the framework portion  134  are supported across the aneurysm opening and are biased against the neck of the aneurysm from outside the aneurysm. 
         [0010]    In the embodiment illustrated in  FIGS. 1C and 1D , the closure structure  131  and the framework portion  134  are deployed outside the internal space of the aneurysm. In an alternative embodiment illustrated in  FIG. 1E , the closure structure  131  and the framework portion  134  are supported across the aneurysm opening and biased against the neck of the aneurysm from inside the aneurysm. 
         [0011]      FIG. 1F  illustrates an alternative deployment system and methodology, wherein a device having at least two anchoring structures is deployed such that the closure structure  131  is positioned to cover the opening of the aneurysm, and the anchoring structures  132 ,  133  are positioned outside the aneurysm and contact an inner blood vessel wall B in proximity to the aneurysm. In this embodiment, the anchoring structures  132 ,  133  may be generally sized and configured to match the inner diameter of the vessel in proximity to the neck of the aneurysm so that following deployment the anchoring structures contact the vessel wall in a substantially continuous manner without straining or enlarging the vessel wall in the area of the aneurysm. In all of these embodiments, following placement of the device, the closure structure substantially covers the aneurysm neck to effectively repair the vessel defect. The anchoring structures do not substantially interfere with flow of blood in the vessel. 
         [0012]    As can be seen in the foregoing, the structures may be difficult to place, particularly in the circuitous blood vessel network of the brain. For the typical aneurysm, extending in a perpendicular manner from its root blood vessel, it may be a challenge to insert the structure into the aneurysm. Moreover, for the device to seal or close the aneurysm, the anchoring structures must mutually press against the aneurysm sides. If one side wall of an aneurysm is not well suited for supporting an anchoring structure, the anchor for the opposite side will not be well supported to provide sufficient pressure on this opposite side wall. This problem drives the design of anchor structures  132  and  133  to be larger, to facilitate receiving sufficient support from the aneurysm interior surface. This, in turn, has the potential to create a mass effect problem, in which the mass of the structures  132  and  133 , plus any clotting that occurs around them, causes the aneurysm to become more massive, potentially pressing against delicate nervous system tissue as a result. 
         [0013]    Moreover, the situation is even more difficult for aneurysms formed at the intersection of vessels, such as a T-intersection or V-intersection.  FIG. 1G  illustrates a saccular bifurcation aneurysm  150  appearing at the intersection of two vessels  152 ,  154 , branching from a stem vessel  156 . Cerebral bifurcation aneurysms are commonly found at the middle cerebral artery, internal carotid artery, anterior communicating artery, basilar artery, posterior communicating artery, and other locations. 
         [0014]    Typically, to place device  130  into a blood vessel of the brain requires a number of steps. First, an incision is made into the femoral artery and a sheath is introduced, extending approximately to the aorta. A first guide catheter is inserted through the sheath and extended up into the carotid artery. A second guide catheter is coaxially introduced through the first guide catheter and extended up into the target aneurysm. Both guide catheters are introduced using a guide wire having a steerable tip of either stainless steel or nitinol. Then, microcatheter introducer is inserted through the guide catheter, to the aneurysm, and device  130  is placed at the aneurysm site. Heretofore, however, once reaching the aneurysm there has been no effective method for positioning a device that requires precise positioning. A device that would require a definite orientation, at least partially inside the aneurysm, presents particular challenges in positioning during implantation 
         [0015]    Another difficulty in delivering a complex implant into an aneurysm is the lack of space to pack such an implant in a lumen at the end of a microcatheter. Any such device must fold into a cylinder having an internal diameter on the order of  1  mm and a length of about 10 mm. Upon delivery it must expand to anchor itself in place and to seal an area that could be as large as 10 mm 2 . The seal over the neck of the aneurysm although thinner than 1 mm, must be strong enough to affirmatively occlude the aneurysm, with a very high degree of certainty. 
       SUMMARY 
       [0016]    The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
         [0017]    In a first separate aspect, the present invention may take the form of a method of implanting a medical device that utilizes an implantation catheter including a first wire and a second wire, electrically insulated from each other, attached to the medical device at a first attachment point and a second attachment point, respectively. The first wire defines a first region susceptible to electrolytic disintegration, contiguous to a the first attachment point, and the second wire defines a second region, also susceptible to electrolytic disintegration, contiguous to the second attachment point. The medical device is positioned at a first desired positioning and electricity is passed through the first wire, sufficient to heat and disintegrate the first region susceptible to electrolytic disintegration, thereby freeing the medical device from the first wire. Then, the medical device is manipulated with the second wire to achieve a second desired positioning. Finally, electricity is passed through the second wire, sufficient to heat and disintegrate the second region susceptible to electrolytic disintegration, thereby freeing the medical device from the second wire. 
         [0018]    In a second separate aspect, the present invention may take the form of a catheter assembly for implanting a medical device, comprising a first wire and a second wire, electrically insulated from each other, attached to the medical device at a first attachment point and a second attachment point, respectively. The first wire defines a first region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to a the first attachment point. Similarly, and the second wire defines a second region susceptible to electrolytic disintegration, by passing an electric current through it, contiguous to the second attachment point. Also, there is a separately controllable electric supply for the first and the second wire, so that the first wire may be disconnected from the medical device, without disconnecting the second wire. 
         [0019]    In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0020]    Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
           [0021]      FIG. 1A  illustrates an enlarged schematic front isometric view of a known implantable device in a deployed condition; 
           [0022]      FIG. 1B  illustrates an enlarged schematic front isometric view of another known implantable device in a deployed condition; 
           [0023]      FIGS. 1C ,  1 D,  1 E, and  1 F schematically illustrate the devices of  FIGS. 1A and 1B  deployed at the site of an aneurysm; 
           [0024]      FIG. 1G  illustrates a saccular bifurcation aneurysm; 
           [0025]      FIG. 2A  is a sectional side view of an aneurysm closure device, according to the present invention, installed in the neck of an aneurysm that has developed at the side of a blood vessel. 
           [0026]      FIG. 2B  is a sectional side view of the aneurysm closure device of  FIG. 2A , according to the present invention, installed in the neck of an aneurysm that has developed at a Y-intersection of blood vessels. 
           [0027]      FIG. 3  is an isometric view of the aneurysm closure device of  FIG. 2A . 
           [0028]      FIG. 4  is an isometric view of an implantation catheter, according to the present invention, with the closure device of  FIG. 2A  retracted. 
           [0029]      FIG. 5  is an isometric view of the catheter of  FIG. 4 , with the closure device of  FIG. 2A  exposed. 
           [0030]      FIG. 6  is an isometric exploded view of the user control portion of the catheter of  FIG. 4 . 
           [0031]      FIG. 7  is a sectional side view of the distal end of the catheter of  FIG. 4 , with the closure device of  FIG. 2A  retracted. 
           [0032]      FIG. 8  is an isometric view of the distal portion of the positioning assembly of  FIG. 4 , with the closure device of  FIG. 2A  extended. 
           [0033]      FIG. 9  is a cross-sectional view of the distal portion of  FIG. 8 , taken at view line  9 - 9 . 
           [0034]      FIG. 10  is a cross-sectional view of the distal portion of  FIG. 8 , taken at view line  10 - 10 . 
           [0035]      FIG. 11  is a cross-sectional view of the distal portion of  FIG. 8 , taken at view line  11 - 11 . 
           [0036]      FIG. 12A  is a side view of the user control of  FIG. 6 , set in a neutral position. 
           [0037]      FIG. 12B  is a side view of the user control of the distal end of  FIG. 7 , corresponding to the user control setting of  FIG. 12A . 
           [0038]      FIG. 13A  is a side view of the user control of  FIG. 6 , set in a skewed position. 
           [0039]      FIG. 13B  is a side view of the user control of the distal end of  FIG. 7 , corresponding to the user control setting of  FIG. 13A . 
           [0040]      FIG. 14A  is a side view of the user control of  FIG. 6 , set in a position skewed opposite to that of  FIG. 13A . 
           [0041]      FIG. 14B  is a side view of the user control of the distal end of  FIG. 7 , corresponding to the user control setting of  FIG. 12A . 
           [0042]      FIG. 15A  is an isometric view of a work piece shown connected to the distal end of  FIG. 7  for ease of presentation and representing a stage in the manufacturing of the closure device of  FIG. 3 . 
           [0043]      FIG. 15B  is a detail view of a portion of  FIG. 15A , as indicated by circle  15 B, in  FIG. 15A . 
           [0044]      FIG. 15C  is an isometric view of a work piece shown connected to the distal end of  FIG. 7  for ease of presentation and representing a further stage in the manufacturing of the closure device of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0045]    In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures or components or both associated with endovascular coils, including but not limited to deployment mechanisms, have not been shown or described in order to avoid unnecessarily obscuring descriptions of the embodiments. 
         [0046]    Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and variations thereof, such as “comprises” and “comprising” are to be construed in an open inclusive sense, that is, as “including, but not limited to.” The foregoing applies equally to the words “including” and “having.” 
         [0047]    Reference throughout this description to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification are not necessarily all referring to the same embodiment. 
         [0048]    Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0049]    The present disclosure is directed to closing a bulge or aneurysm formed in blood vessel, such as an artery or vein (referred to more generally herein as “vessel”), in a manner that does not suffer from some of the drawbacks of prior art methods. For example, in the prior art method involving the insertion of a wire coil into the aneurysm, the resultant blood clot can create problems through its mass and the possibility of pressing against nearby nerves. In addition, the wire coil can have the effect of keeping the neck open, possibly causing another aneurysm to form. 
         [0050]    The embodiments of the present disclosure combine the closure structure and the anchoring structure into a single unit to improve compactness, allow delivery into the tortuous intracranial circulation system via a microcatheter, and to improve the aneurysm neck closure. In addition, the embodiments of the present disclosure provide enhanced rotation control and placement of the device within the aneurysm via two attachment points for a microcatheter. Moreover, markers can be used at the junctions of the device structure to aid in tracking the movement of the closure device during insertion and placement. 
         [0051]    Referring to  FIG. 2A , a preferred embodiment of an aneurysm closure device  10  is shown in its implanted environment of an aneurysm  12  attached to a root vessel  14 .  FIG. 2B  shows the device  10 , implanted environment, on an aneurysm that has developed at a Y-intersection of blood vessels.  FIG. 3  shows a more detailed perspective view of closure device  10 . In  FIG. 2A , aneurysm closure device  10  is held in place by four anchors: A first aneurysm anchor  16 A and a first root vessel anchor  18 A mutually anchor closure device  10  to a distal side of the aneurysm  12 , while a second aneurysm anchor  16 B and a second root vessel anchor  18 B, mutually anchor closure device  10  on a proximal side of the aneurysm  12 . Referring to  FIG. 3 , it is seen that in the installed state of  FIG. 2A , a seal  20  is placed over the neck of aneurysm  12 , thereby preventing further blood flow into aneurysm  12  and causing it to atrophy over time. 
         [0052]    First anchors  16 A and  18 A act as a first clip, mutually applying gentle pressure toward each other, thereby clipping about the interposed tissue. In similar manner, second anchors  16 B and  18 B act as a second clip. Working together, anchors  16 A,  18 A,  16 B and  18 B hold the seal  20  in place, thereby blocking the flow of blood into aneurysm  12 . 
         [0053]    Closure device  10  includes a wire frame  22 , which is made of nitinol, or some other shape-memory material. Prior to use, closure device  10  is maintained at a temperature below human body temperature, thereby causing wire frame to assume the shape shown in  FIG. 3 , when first pushed out of terminal lumen  56 . In one preferred embodiment, after warming to  37 C, however, anchors  16 A and  18 A, are urged together, as are anchors  16 B and  18 B, thereby more securely clipping to the interposed tissue. In another preferred embodiment, however, the natural spring force of the nitinol causes device  10  to expand when it is pushed out of fossa  56 , and it retains this shape during positioning and use. A set of eyeholes  24  are defined by frame  22  and expanded poly tetrafluoroethylene (ePTFE) thread or fiber  26  is threaded into these eyeholes  24  to form a lattice. The eyeholes  24  are filled with gold solder ( FIG. 15B ), thereby anchoring thread  26  and closing eyeholes  24 . Accordingly, although materials may be useable as thread  26  whatever material is used must be capable of withstanding the temperature of molten gold solder, which is typically 716° C. The ePTFE lattice work  26  is then coated with silicone  28 , which in one preferred embodiment is cured in situ to form the seal  20 . In another preferred embodiment, sheets of silicone are cut to the correct dimensions and adhered together about the ePTFE lattice  26 . In the embodiment shown, silicone  28  is placed on the aneurysm anchors  16 A and  16 B, but in an alternative embodiment, the ePTFE portion on anchors  16 A and  16 B are there to complete the threading arrangement, but are not coated with silicone. In another alternative preferred embodiment more, and smaller, eyeholes  24  are defined. In a preferred embodiment, two spots of radiopaque material  30  are placed at the tip of each aneurysm anchor  16 A and  16 B and one spot of radiopaque material  30  is placed at the tip of each root vessel anchor  18 A and  18 B. Accordingly, a surgeon placing closure device  10  can determine the position of closure device  10 , through a sequence of X-ray images, relative to the contours of the aneurysm  12 , which is shown by the use of a radiopaque dye, placed into the bloodstream. 
         [0054]    In an alternative preferred embodiment at least some of the anchors, serving the function of anchors  16 A- 18 B, are made of a thin sheet of nitinol, or a thin sheet of nitinol covered with a biocompatible silicone, or polymeric material, for forming a good grip on the tissue it contacts. In yet another embodiment, at least some of the anchors are made entirely of polymeric material. In an additional preferred embodiment, ePTFE thread  26  lattice, is replaced with metal filigree, made of a metal such as gold, having a high melting point. In addition, there is a broad range of engineered materials that can be created for this type of purpose. In yet another preferred embodiment, anchors, serving the function of anchors  16 A- 18 B, are made of wire loops or arcs, some of which support an ePTFE reinforced silicone barrier, thereby providing a closure mechanism for an aneurysm. 
         [0055]    Referring to  FIGS. 4-14B , prior to installation, closure device  10  forms a part of a micro-catheter closure device installation assembly  40 , which although specifically adapted to install closure device  10  at an aneurysm also embodies mechanisms that could be used for other tasks, particularly in accessing tissue through a blood vessel. Assembly  40  comprises a micro-catheter subassembly  42 , and a user-control subassembly  44 . A first wire-head handle  46 A and a second wire-head handle  46 B, are attached to a first wire  48 A and a second wire  48 B, respectively. 
         [0056]    Referring to  FIGS. 7-14B , in micro-catheter subassembly  42 , wires  48 A and  48 B pass through a flexible tube  50 , which has an exterior diameter of about  1 . 5  mm, and which has a hydrophilic exterior surface, to aid in progressing toward a blood vessel destination. Tube  50  is divided into a proximal single lumen extent  52 , near-distal dual lumen extent  54 , and a distal fossa or wide-lumen extent  56 . This construction permits for the control of the shape and orientation of distal portion of tube  50 , and for the positioning of closure device  10 , after it has been pushed out of fossa  56 . As shown in  FIG. 13A and 13B , if the first wire-head handle  46 A is retracted relative to second wire-head handle  46 B, then distal fossa  56  bends towards handle  46 A. Likewise, as shown in  FIGS. 14A and 14B , if the second wire-head handle  46 B is retracted relative to first wire-head handle  46 A, then distal fossa  56  bends towards handle  46 B. The orientation of fossa  56 , and the direction it turns to when handle  46 A or  46 B is retracted, can be changed by rotating the wire-head handles  46 A and  46 B, together. After closure device  10  is pushed out of fossa  56 , it responds in like manner, bending toward wire-head handle  46 A, when handle  46 A is retracted, and toward handle  46 B, when handle  46 B is retracted. It can be rotated, and the direction that it bends when wire  46 A or  46 B is pulled can be determined, by rotating the handles  46 A and  46 B, together. This freedom in positioning is important during the implantation process, when as shown in  FIGS. 2A and 2B  anchors  16 A and  16 B must be maneuvered through the neck of the aneurysm  12 , and positioned so that they extend along the same dimension as root vessel  14 . The radiopaque markings  30  ( FIG. 3 ) are invaluable during this process. 
         [0057]    Referring now to  FIG. 6 , subassembly  42  is threaded through an end cap  60 , and passes into a transparent chamber  62 , where wires  48 A and  48 B, emerge from tube  50 , pass through a slider  64  and are separately anchored in handles  46 A and  46 B, respectively. The travel extent of slider  64  is limited by a stop pin  66  and a slot  68 . 
         [0058]    In one preferred embodiment, wires  48 A and  48 B are electrically isolated from each other, either by a thin layer of insulating material or simply by the layout of device  10  and the conductive characteristics of wires  48 A and  48 B. Each include a region  70  ( FIGS. 7 and 8 ) that is susceptible to electrolytic disintegration. To detach closure device  10 , after partial placement and initial orientation, which may be checked by reference to radio opaque markings  30 , an electric current is passed through wire  48 A, causing region  70  of wire  48 A to electrolytically disintegrate. After this, wire  48 B may be used to further orient aneurysm device  10 . 
         [0059]    Although after the freeing of seal  20  from wire  48 A, control may be less certain, it may in some instances be possible to have a greater freedom of positioning device  10  when a single wire  48 B is attached, only. This may be particularly true when a portion of device  10  has contacted body tissue, for example entering aneurysm  12 , and it is desired to orient device  10  properly for the setting of anchors  16 A and  16 B and  18 A and  18 B so that the extend along the length of blood vessel  14 . Again verifying orientation by way of markings  30 , when device  10  is properly oriented electricity is passed through wire  48 B, causing its region  70  to disintegrate, and freeing closure device  10  from wires  48 A and  48 B, entirely so that it can be left in place in its target location, sealing aneurysm  12 . In a preferred embodiment, handles  46 A and  46 B each includes an electrical contact connected to wire  48 A and  48 B, respectively, for attaching to a source of electricity for performing the above-described step. 
         [0060]    Subassembly  42  is introduced into the femoral artery and guided through the carotid artery into the brain&#39;s arterial system, and further guided to the aneurysm  12 . At this point closure device  10  is pushed out of fossa  56 , anchors  16 A and  16 B are guided into aneurysm  12 , and anchors  18 A and  18 B are positioned in root artery  14 . Then a pulse of electricity severs closure device  10  from wires  48 A and  48 B and closure device  10  is installed in place. 
         [0061]    Wires  48 A and  48 B are made of stainless steel alloy  304 , which may also be referred to as alloy  18 - 8 . This material is coated with poly tetrafluoroethylene, except for at detachment points  70  and the points where they are connected to a source of electricity. The nitinol alloy that frame  22  ( FIG. 3 ) is made of is 54.5% to 57% nickel, with the remainder titanium, which forms a super-elastic alloy. The introducer tube  50  is made of high density polyethylene, coated at the distal tip with a hydrophilic coating. Finally, the silicone  28  of the closure device  10  is silicone MED 4820 or MED-6640, which is a high tear strength liquid silicone elastomer, having a Shore A durometer reading of  20 - 40 . A MED6-161 Silicone Primer is used to attach silicone  28  to Nitinol frame  22 . 
         [0062]    While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations, thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.