Abstract:
A complex coil configured such that in a relaxed, minimum energy state configuration loops are formed having various orientations relative to each other. The complex coil provide improved thrombus formation and reduced rotation or tumbling once implanted. The complex coil is formed of a material that may be deformed for purposes of placing the complex coil into a catheter and returns to a complex shape that includes said loops once deployed.

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/096,740 filed Sep. 12, 2008, entitled Three-Dimensional Complex Coil, which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the field of vascular occlusion devices and methods. More specifically, it relates to an apparatus and method for embolizing a targeted site such as an aneurysm in the blood vessel. 
     BACKGROUND OF THE INVENTION 
     The prior art contemplates a number of methods and devices for treating an aneurysm using three-dimensional (3-D) shaped coils, sometimes referred to as “complex coils.” For example, U.S. Pat. No. 5,766,219 to Horton, the contents of which are incorporated by reference, shows a hollow coil structure. U.S. Pat. No. 5,382,259 to Phelps and U.S. Pat. No. 4,994,069 to Ritchart, the contents of which are incorporated by reference, show other 3-D coil designs. U.S. Pat. No. 6,635,069 to Teoh, the contents of which are incorporated by reference, teaches a series of non-overlapping loops. U.S. Pat. No. 6,860,893 to Wallace, the contents of which are incorporated by reference, shows alternative complex coils. U.S. Pat. No. 6,638,291 to Ferrera, the contents of which are incorporated by reference, shows a device similar to Teoh&#39;s and Wallace&#39;s except that a J-shaped proximal segment extends away from the complex portion of the device. 
     The following patents and published patent applications provide further background and are also incorporated herein by reference: U.S. Pat. No. 6,010,498 to Guglielmi; U.S. Pat. No. 6,478,773 to Gandhi; U.S. Pat. No. 5,957,948 to Mariant; U.S. Pat. No. 5,911,731 to Pham; U.S. Pat. No. 4,957,501 to Lahille; and U.S. Publication Nos. 2005/0192618 to Porter, 2005/0192621; to Wallace; and 2002/0107534 to Schaefer; 
     There is, however an ongoing need to provide more advanced and improved complex coils that exhibit greater stability after deployment and increased efficacy for treating aneurysms. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention provides improved devices and methods for treating an aneurysm. Another aspect of the present invention pertains to a device that includes a strand of material that self-forms into a compound shaped series of loops oriented predominately longitudinally about and through a central axis when the device is in a relaxed or low energy state configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a device according to the present invention; 
         FIG. 2  is a perspective view of a portion of a microcoil employed to form a device according to the present invention; 
         FIG. 3  is a perspective view of an embodiment of a mandrel employed to fabricate a device according to the present invention; 
         FIG. 4A-4B  are illustrations of a frame of reference in which a device according to the present invention may be described; 
         FIG. 5  is a perspective view of a wire model of an embodiment of a device according to the present invention; 
         FIG. 6  is an illustration of a frame of reference in which a device according to the present invention may be described; 
         FIGS. 7A-7D  are perspective views of a wire model of an embodiment of a device according to the present invention; 
         FIGS. 8A-8D  are perspective views of a wire model of an embodiment of a device according to the present invention; 
         FIGS. 9A-9D  are perspective views of a wire model of an embodiment of a device according to the present invention; 
         FIG. 9E  is a perspective view of an embodiment of a device according to the present invention; 
         FIG. 10  is a perspective view of an embodiment of a mandrel employed to fabricate a device according to the present invention; and 
         FIG. 11  is a perspective view of an embodiment of a device according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Referring first to  FIGS. 1 and 2 , a microcoil vaso-occlusive device  10 , in accordance with a preferred embodiment of the invention is shown. For the sake of clarity and in order to provide greater perspective to the  FIG. 1 , the device  10  of  FIG. 1  is shown with a central axis  20  that appears as a dowel, i.e. appears exaggerated in size. It is to be understood that central axis  20  is merely an axis and is not a physical component of the device  10 . The device  10  comprises a suitable length of wire  12  formed into the primary configuration of a helical microcoil  14 . Suitable materials for the microcoil  14  include platinum, rhodium, palladium, rhenium, tungsten, gold, silver, tantalum, and various alloys of these metals. Various surgical grade stainless steels may also be used. Preferred materials include the platinum/tungsten alloy known as Platinum 479 (92% Pt, 8% W, available from Sigmund Cohn, of Mount Vernon, N.Y.) and titanium/nickel alloys (such as the titanium/nickel alloy known as “Nitinol”). Another material that may be advantageous is a bimetallic wire comprising a highly elastic metal with a highly radiopaque metal. Such a bimetallic wire would also be resistant to permanent deformation. An example of such a bimetallic wire is a product comprising a Nitinol outer layer and an inner core of pure reference grade platinum, available from Sigmund Cohn, of Mount Vernon, N.Y., and Anomet Products, of Shrewsbury, Mass. 
     The wire  12  employed to form microcoil  14  has a diameter in the range of 0.001 to 0.005 inches. The microcoil  14  has a diameter that is typically in the range of about 0.008 to 0.016 inches. The axial length of the microcoil  14  may be anywhere from about 5 to 100 cm. 
     The primary winding of the microcoil  14  is applied under tension. The amount of tension and the pitch of the primary winding determine the stiffness of the microcoil  14 . These parameters can be varied along the length of the microcoil  14  to form a microcoil having different degrees of stiffness along its length, which may be advantageous in certain applications. 
     The primary microcoil  14  is formed into the secondary configuration by heat treatment, as is well known in the art. For example, the annealed primary coil may be initially placed into the secondary configuration by winding or wrapping the microcoil  14  around a suitably shaped and sized mandrel, or fixture, of refractory material, and then subjecting the microcoil wrapped mandrel to an annealing temperature for a specified period of time. For example, an annealing temperature of about 500 degrees Celsius to about 1000 degrees Celsius, is maintained for about 30 to 90 minutes, then cooled to room temperature and ultrasonically cleaned. The resultant secondary configuration is thereby made permanent and becomes the relaxed or minimum energy state configuration of the microcoil  14 . 
       FIG. 3  shows a mandrel or heat treatment fixture  50  used in the manufacture of the preferred embodiment of the invention. The mandrel  50  comprises a shaft  15  defining a central axis  20  through the mandrel. The exemplary mandrel  50  shown in  FIG. 3  further employs assemblies  30   a - e  separated by disks  40 . As illustrated, the assemblies  30   a - e  may have attached thereto pins  32 . The pins  32  may be formed in various diameters and cross-sectional shapes, such as circular, ovular, triangular, or rectangular shapes. For example, the pins  32  may have a diameter of about 3 mm to 25 mm. Furthermore, the pins  32  may be attached to the assembly body  34  in either a regular, centered configuration relative to the assembly body  34 , or the pins  32  may be attached in an irregular, off-centered configuration relative to the assembly body  34 . For example, as best illustrated in  FIG. 10 , an assembly  30   b  comprises a pin  32   a  attached to the assembly body  34  in an irregular configuration, and a pin  32   b  attached to the assembly body  34  in a regular configuration. The regular and irregular configurations of the pins  32  relative to the assembly bodies  34  are employed, at least in part, in order that adjacent loops may be tangentially-interconnected to one another. Stated alternatively, the regular and irregular configurations of the pins  32  relative to the assembly bodies  34  may facilitate interconnecting adjacent loops such that the adjacent loops connect with one another at a shared or common approximate tangent. 
     The assembly bodies  34  may also be configured in various sizes and shapes, for example, an assembly body  35  of an assembly  30   a , as seen in  FIG. 3 , is formed in the general shape of a trapezoid. The assembly bodies  34  may be formed in numerous other shapes such as rectangles, triangles, spheres, or parallelograms. As illustrated in  FIG. 3 , the assembly body  34  and the pins  32  of the assembly  30   a - e  may be configured so as to form a cross or plus sign when placed over the shaft  15  and viewed along the central axis  20 . As will also be noted from  FIG. 3 , the assemblies  30   a - e  may be mounted over the shaft  15  at different radial orientations relative to the other assemblies  30   a - e  mounted on the shaft  15 . For example, the assembly  30   b  is askew from the general orientation of the assemblies  30   a  and  30   c - e.    
     To form the secondary configuration of the microcoil  14 , the microcoil  14  is first anchored to an end of the mandrel  50 . The microcoil  14  is then wrapped around either a first disk  40  or a first pin  32  to form loops  102  or  100 , respectively, see  FIG. 1 . Upon completion of a first loop, the microcoil  14  may, for example, be brought to a second pin  32 , if fabrication began on a first pin  32 , or to a first disk  40 , if fabrication began on a first pin  32 , or to a first disk  40 , if fabrication began on a pin  32 . In a preferred embodiment, the microcoil  14  does not transition from one disk  40  to another disk  40  without wrapping around at least one pin  32  there between. The microcoil  14  is wrapped around the second location to form a second loop and the process is repeated until the desired device  10  has been formed. During the secondary winding process, the primary coil  14  is kept under tension. The amount of tension is adjusted to control the structural characteristics of the secondary configuration. 
     The number of revolutions or turns that the primary coil  14  is wound around the disks  40  or the pins  32  will depend on the configuration of the loops  100  and  102  of the device  10 . For example, if a loop  102  is interposed between two loops  100  that are connected to the loop  102  at approximately 180 degrees apart, the loop  102  may be wound 1.5 revolutions around the disk  40  from which the loop  102  is formed. The number of revolutions that the primary coil  14  is wound around the disks  40  or the pins  32  may also be adjusted in order to control structural characteristics of the secondary structure. The direction of the revolutions or turns that the primary coil  14  is wound around the disks  40  or the pins  32  so as to minimize the space or length of coil  14  occurring between adjacent connected loops. For example, the direction of the revolutions may alternate between adjacent connected loops. 
     In order to facilitate the detailed description of the orientation and position of the various loops that comprise certain embodiments of the device  10 ,  FIGS. 4A and 4B  illustrate a general frame of reference. Devices according to the present invention may be conceptualized, for example, as employing a series of interconnected loops that are either oriented in a planar manner around the circumference  30  of the central axis  20  or oriented so as to intersect the central axis  20 . As described above, loops are either formed by wrapping microcoil  14  around a disk  40 , forming loops  102 , or a pin  32 , forming loops  100 . Regarding the loops  100 , loops that are oriented around the circumference  30  of the central axis  20 , viewed in cross-section, these loops create a plane that forms a tangent  130  to the circumference  30 . A radius  120  is formed by connecting the central axis  20  and the tangent  130 . A tangent angle α (alpha) is determined by measuring the angle of the radius  120  from zero degrees in an X, Y plane. The loops  100  that are oriented around the circumference  30  of the central axis  20  are formed, for example, by wrapping of the microcoil  14  around the pins  32  of the assembly  32   a - e , see  FIG. 3 . As will be noted, the length of radius  120  may vary such that while a first and second loop  100  of device  10  may have equal tangent angles α they may be positioned at different points along the length of radius  120 . 
     With respect to those loops  102  that intersect the central axis  20 , such loops  102  are formed by wrapping the microcoil  14  around the disks  40 . The orientation of loops  102  intersecting the central axis  20  are described in terms of the loop&#39;s  102  Z,Y offset or intersecting angle μ (mu), as illustrated in  FIG. 4A . Additionally, in certain configurations it may also be necessary to refer to the loop&#39;s  102  X,Y angle of rotation or rotational angle β (beta). For example, a loop  102  that intersects the central axis  20  substantially perpendicular to central axis  20  would have a intersecting angleμ of zero degrees and a rotational angle β of zero degrees. 
     The following provides detailed descriptions of the configurations of various example devices  10  according to certain embodiments of the present invention. Example 1 will be described in the form of a table, as well as textually with respect to the above described reference scheme. Various other examples will be described only in the form of a table according to the same principles and procedure describe with respect to Example 1. 
     With respect to Tables 1-4, loop diameters are provided for each of the loops forming the exemplary devices of Examples 1-4. The loop diameters are referenced to a “nominal” diameter which is determined by the size of the vascular irregularity or aneurysm intended for treatment. Each loop diameter is referenced as either equal to the nominal diameter or a variation from the nominal diameter. For example, if the nominal diameter is equal to 6 mm, each loop characterized as nominal has a diameter of 6 mm. A loop characterized as “−2” has a 4 mm diameter. 
     Example 1 
     
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 DESCRIPTION OF EXAMPLE 1 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Rota- 
               
               
                   
                 Loop 
                   
                 Tangent 
                   
                 Intersecting 
                 tional 
               
               
                 Loop 
                 Diameter 
                 Assembly 
                 Angle (α) 
                 Disk 
                 Angle (μ) 
                 Angle (β) 
               
               
                 No. 
                 (mm) 
                 No. 
                 (Deg.) 
                 No. 
                 (Deg) 
                 (Deg) 
               
               
                   
               
               
                 201 
                 −2 
                 1 
                  0 
                   
                   
                   
               
               
                 202 
                 −1 
                 1 
                 270 
                   
                   
                   
               
               
                 203 
                 Nominal 
                   
                   
                 1 
                 90 
                  0 
               
               
                 204 
                 −1 
                 2 
                 135 
                   
                   
                   
               
               
                 205 
                 Nominal 
                   
                   
                 2 
                 90 
                  0 
               
               
                 206 
                 −1 
                 3 
                 225 
                   
                   
                   
               
               
                 207 
                 −1 
                 3 
                 315 
                   
                   
                   
               
               
                 208 
                   −1/2 
                   
                   
                 3 
                 75 
                 45 
               
               
                 209 
                 −1 
                 4 
                 135 
                   
                   
                   
               
               
                 210 
                   −1/2 
                   
                   
                 4 
                 345  
                 45 
               
               
                 211 
                 −1 
                 5 
                 315 
                   
                   
                   
               
               
                 212 
                 −2 
                 5 
                 225 
               
               
                   
               
             
          
         
       
     
     With reference to  FIGS. 5 and 9E , device  200  includes loops  201 - 212 . Loops  201 - 212  connect to one another in the same order as they are numbered. As noted in TABLE 1 and illustrated in  FIG. 6 , The loop  201 , the first loop of device  200 , is oriented so as to have a tangent angle α of zero (0) degrees with the device  200  oriented such that loop  201  is nearest the viewer&#39;s eye when the device is viewed along the central axis  20 . That is to say, the first loop will serve to define the start position for reference to the remaining loops  202 - 212 . It should also become apparent based on the above description of devices according to the present invention, that each loop is either characterized as a loop  100  or a loop  102 . With respect to loops  100 , for the sake of description, loops  100  will be referenced according to the common or shared assemblies  30  from which the loop is formed, as well as according to each loop&#39;s  100  tangent angle α. Assemblies  30  are referenced starting from the first loop  100 . For example, loop  201  and  202  would have been formed from the same assembly and such assembly would be the first assembly, because it coincides with loop  201 , see TABLE 1. Loops  102  may optionally be placed between the loops  100 . As with reference to the assemblies  30  and the loops  100 , reference to the disks from which the loops  102  are formed begin with the first loop  102  occurring in the device. 
     With specific reference to TABLE 1 and  FIGS. 4A through 6  and  9 E, the configuration of device  200  will be described. Loop  201  is oriented so as to have a tangent angle α of about zero degrees and defines the first assembly. Loop  202  is also within the first assembly and has a tangent angle α of about 270 degrees. Loop  203  is the first loop intersecting the central axis  20  and therefore defines the first disk  40 . Loop  203  is positioned approximately perpendicular through the central axis  20  and therefore has an intersecting angle μ of about 90 degrees and a rotational angle β of about zero degrees. Loop  204  is formed by a second assembly and has a tangent angle α of about 135 degrees. Loop  205  defines the second disk and has an intersecting angle μ of about 90 degrees and a rotational angle β of about zero degrees. Loop  206  defines the third assembly and has a tangent angle α of about 225 degrees. Loop  207  is also positioned on the third assembly and has a tangent angle α of about 315 degrees. Loop  208  is an intersecting loop  102  and defines a third disk. Loop  208  intersects the central axis  20  at an angle nonperpendicular to the axis  20 . Loop  208  has an intersecting angle of about 75 degrees read on the Z,Y plane. Furthermore, loop  208  can be described as being rotated about the X,Y plane, i.e. it has a rotational angle β of about 45 degrees. Loop  209 , is positioned about a circumference  30  of the central axis  20  and therefore defines a forth assembly. Loop  209  has a tangent angle α of about 135 degrees. Loop  210  defines a forth disk and has an intersecting angle μ of about 345 degrees and a rotational angle β of about 45 degrees. Loop  211  defines a fifth assembly and has a tangent angle α of about 315 degrees. Finally, loop  212  is also formed by the fifth assembly and has a tangent angle α of about 225 degrees. 
     As apparent from the positional description of loops  204 ,  206 ,  207 ,  209 ,  211 , and  212 , the planes defined by these loops are approximately 45 degrees askew from the planes defined by loops  201  and  202 . This is best explained by the fact that loop  201  defines the reference plane of the device. From a fabrication perspective, the offset is best illustrated in  FIG. 3 . The mandrel  50  is configured such that the assembly  30   b  is oriented 45 degrees askew to the assemblies  30   a  and  30   c - e.    
     Example 2 
     With reference to  FIGS. 7A-7D , device  300  includes loops  301 - 312 . The orientation of each loop with reference to the reference frame described above is provided in TABLE 2. 
     
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 DESCRIPTION OF EXAMPLE 2. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Rota- 
               
               
                   
                 Loop 
                   
                 Tangent 
                   
                 Intersecting 
                 tional 
               
               
                 Loop 
                 Diameter 
                 Assembly 
                 Angle (α) 
                 Disk 
                 Angle (μ) 
                 Angle (β) 
               
               
                 No. 
                 (mm) 
                 No. 
                 (Deg.) 
                 No. 
                 (Deg) 
                 (Deg) 
               
               
                   
               
               
                 301 
                 −2 
                 1 
                  0 
                   
                   
                   
               
               
                 302 
                 −1 
                 1 
                  90 
                   
                   
                   
               
               
                 303 
                 Nominal 
                   
                   
                 1 
                 90 
                 0 
               
               
                 304 
                 −1 
                 2 
                 315 
                   
                   
                   
               
               
                 305 
                 −1 
                 2 
                 225 
                   
                   
                   
               
               
                 306 
                 Nominal 
                   
                   
                 4 
                 90 
                 0 
               
               
                 307 
                 Nominal 
                 3 
                  90 
                   
                   
                   
               
               
                 308 
                 Nominal 
                   
                   
                 3 
                 90 
                 0 
               
               
                 309 
                 −1 
                 4 
                 315 
                   
                   
                   
               
               
                 310 
                 −1 
                 4 
                 225 
                   
                   
                   
               
               
                 311 
                 Nominal 
                   
                   
                 4 
                 90 
                 0 
               
               
                 312 
                 −2 
                 5 
                  90 
               
               
                   
               
             
          
         
       
     
     Example 3 
     With reference to  FIGS. 8A-8D , device  400  includes loops  401 - 412 . The orientation of each loop with reference to the reference frame described above is provided in TABLE 3. 
     
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 DESCRIPTION OF EXAMPLE 3 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Rota- 
               
               
                   
                 Loop 
                   
                 Tangent 
                   
                 Intersecting 
                 tional 
               
               
                 Loop 
                 Diameter 
                 Assembly 
                 Angle (α) 
                 Disk 
                 Angle (μ) 
                 Angle (β) 
               
               
                 No. 
                 (mm) 
                 No. 
                 (Deg.) 
                 No. 
                 (Deg) 
                 (Deg) 
               
               
                   
               
               
                 401 
                 −2 
                 1 
                  0 
                   
                   
                   
               
               
                 402 
                 −1 
                 1 
                  90 
                   
                   
                   
               
               
                 403 
                 Nominal 
                   
                   
                 1 
                 90 
                   
               
               
                 404 
                 −1 
                 2 
                 315 
                   
                   
                   
               
               
                 405 
                 Nominal 
                   
                   
                 2 
                 90 
                 0 
               
               
                 406 
                 −1 
                 3 
                  90 
                   
                   
                   
               
               
                 407 
                 −1 
                 3 
                 180 
                   
                   
                   
               
               
                 408 
                 Nominal 
                   
                   
                 3 
                 345  
                 45  
               
               
                 409 
                 −1 
                 4 
                 315 
                   
                   
                   
               
               
                 410 
                 −Nominal 
                   
                   
                 4 
                 90 
                 0 
               
               
                 411 
                 −1 
                 5 
                 180 
                   
                   
                   
               
               
                 412 
                 −2 
                 5 
                  90 
               
               
                   
               
             
          
         
       
     
     Example 4 
     With reference to  FIG. 9A-9D , device  500  includes loops  501 - 512 . The orientation of each loop with reference to the reference frame described above is provided in TABLE 4. 
     
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 DESCRIPTION OF EXAMPLE 4 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Rota- 
               
               
                   
                 Loop 
                   
                 Tangent 
                   
                 Intersecting 
                 tional 
               
               
                 Loop 
                 Diameter 
                 Assembly 
                 Angle (α) 
                 Disk 
                 Angle (μ) 
                 Angle (β) 
               
               
                 No. 
                 (mm) 
                 No. 
                 (Deg.) 
                 No. 
                 (Deg) 
                 (Deg) 
               
               
                   
               
               
                 501 
                 −2 
                 1 
                  0 
                   
                   
                   
               
               
                 502 
                 −1 
                 1 
                  90 
                   
                   
                   
               
               
                 503 
                 Nominal 
                   
                   
                 1 
                 90 
                  0 
               
               
                 504 
                 −1 
                 2 
                 315 
                   
                   
                   
               
               
                 505 
                 Nominal 
                   
                   
                 2 
                 90 
                  0 
               
               
                 506 
                 −1 
                 3 
                  90 
                   
                   
                   
               
               
                 507 
                 −1 
                 3 
                 180 
                   
                   
                   
               
               
                 508 
                   −1/2 
                   
                   
                 3 
                 75 
                 270 
               
               
                 509 
                 −1 
                 4 
                  0 
                   
                   
                   
               
               
                 510 
                   −1/2 
                   
                   
                 4 
                 345  
                 270 
               
               
                 511 
                 −1 
                 5 
                 180 
                   
                   
                   
               
               
                 512 
                 −2 
                 5 
                  90 
               
               
                   
               
             
          
         
       
     
     Example 5 
     With reference to  FIG. 11 , device  600  includes loops  601 - 611 . As apparent from  FIG. 11 , loops  601 - 611  alternate between tangential loops  100  and intersecting loops  102 . Stated alternatively, each loop  100  is interposed between two loops  102  and each loop  102  is interposed between two loops  100 . As also apparent from  FIG. 11 , each adjacent pair of loops reside in planes that are approximately perpendicular to one another, i.e. adjacent pairs of loops reside in planes that intersect to form an angle of approximately 90 degrees. 
     In order to deliver the device  10  to the target, such as an aneurysm, the proximal end of the microcoil  14  of device  10  is attached to the distal end of an elongate delivery device, such as a guidewire or microcatheter (not shown). The attachment may be by any of a number of ways known in the art, as exemplified by the following U.S. patents, the disclosures of which are expressly incorporated herein by reference: U.S. Pat. No. 5,108,407 to Geremia et al.; U.S. Pat. No. 5,122,136 to Guglielmi et al.; U.S. Pat. No. 5,234,437 to Sepetka; U.S. Pat. No. 5,261,916 to Engelson; U.S. Pat. No. 5,304,195 to Twyford, Jr. et al.; U.S. Pat. No. 5,312,415 to Palermo; U.S. Pat. No. 5,423,829 to Pham et al.; U.S. Pat. No. 5,522,836 to Palermo; U.S. Pat. No. 5,645,564 to Northrup et al.; U.S. Pat. No. 5,725,546 to Samson; U.S. Pat. No. 5,800,453 to Gia; U.S. Pat. No. 5,814,062 to Sepetka et al.; U.S. Pat. No. 5,911,737 to Lee et al.; U.S. Pat. No. 5,989,242 to Saadat et al.; U.S. Pat. No. 6,022,369 to Jacobsen et al.; U.S. Pat. No. 6,063,100 to Diaz et al.; U.S. Pat. No. 6,068,644 to Lulo et al.; and U.S. Pat. No. 6,102,933 to Lee et al. 
     A method for treating a vascular target with the device  10  may include visualizing the target vascular site by means well-known in the art. The target vascular site may be, for example, an aneurysm branching off a parent artery. Such an aneurysm may have a dome connected to the branch artery by a neck. A catheter is passed intravascularly until it enters the dome of the aneurysm via the neck. The device  10  is passed through the catheter with the assistance of the guidewire or microcatheter until a distal end of the device  10  enters the dome of the aneurysm. 
     As the device  10  enters the aneurysm, it attempts to assume its secondary configuration. Because the microcoil, in its secondary configuration, is larger than the aneurysm, however, it is constrained into a deployed configuration in which it tends to line the periphery of the aneurysm. In this deployed configuration, the microcoil is in an energy state that is substantially higher than its minimum energy state. Thus, when the device is deployed inside a vascular site such as an aneurysm, the confinement of the device within the site causes the device to assume a three-dimensional configuration that has a higher energy state than the minimum energy state. Because the minimum energy state of the device is larger (in at least one dimension) than the space in which it is deployed, the deployed device is constrained by its intimate contact with the walls of the aneurysm from returning to its minimum energy state configuration. Therefore, the device still engages the surrounding aneurysm wall surface, thereby minimizing shifting or tumbling due to blood flow dynamics. Furthermore, the minimum energy state secondary configuration (to which the device attempts to revert) is not one that is conducive to “coin stacking”, thereby minimizing the degree of compaction that is experienced. 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.