Abstract:
The present invention involves a magnetic detachable embolization apparatus and method for embolizing an aneurysm of a blood vessel. The apparatus includes an element adapted to be detachably connected to a distal portion of a catheter for insertion within an aneurysm of a blood vessel, the element being shaped to be retained within the aneurysm, and one or more magnets carried by the element to internally induce a magnetic field from within the aneurysm to control a magnetic field controllable embolic to embolize the aneurysm. The method includes providing a magnetic-field controllable embolic within or adjacent to an aneurysm in a blood vessel, and internally inducing a magnetic field from within the aneurysm to control the magnetic-field controllable embolic to embolize the aneurysm.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates, in general, to an apparatus and method for forming an occlusion in a mammalian body, and, in particular to an apparatus and method for internally inducing a magnetic field in an aneurysm to embolize the aneurysm with a magnetically-controllable substance.  
         BACKGROUND  
         [0002]    Like all parts of the body, the brain is composed of living cells that require a blood supply to provide oxygen and nutrients. A hemorrhage in a blood vessel in the brain or in the space closely surrounding the brain is a common cause of strokes. Hemorrhage refers to bleeding into the brain, usually because of a problem with a blood vessel. The problem is often an aneurysm.  
           [0003]    An aneurysm is an abnormal bulging outward of blood vessel wall. The wall may smoothly bulge outward in all directions (a fusiform aneurysm) or it may form a sack arising from one wall (a saccular aneurysm). If the aneurysm ruptures, a hemorrhage occurs. This can compress and irritate the surrounding blood vessels, resulting in a reduced supply of oxygen and nutrients to the cells, possibly causing a stroke.  
           [0004]    Aneurysms can be treated from outside the blood vessel using surgical techniques or from inside the blood vessel using endovascular techniques. Endovascular treatment of an aneurysm is performed using a catheter. X-ray, magnetic resonance imaging (MRI) equipment, or other visualization equipment may be used to view the progress during the procedure.  
           [0005]    A magnetically directable embolic such as an acrylic, iron-containing glue has been proposed to fill or obliterate aneurysms. The embolic is delivered by means of a catheter and is directed into an aneurysm with an external magnetic field generated by a permanent magnet or electrogmanetic device used for Stereotaxis procedures such as a prototype device made by Stereotaxis Inc. of St. Louis, Mo. An example of such a device is shown and described in U.S. Pat. No. 6,014,580 to Blume, et al. Problems with this approach include that the Stereotaxis machine is cumbersome and expensive and, in some cases, the external magnetic field produced by the Stereotaxis machine is not strong enough to control delivery of the iron-containing, magnetically-directable glue into the aneurysm.  
         SUMMARY OF THE INVENTION  
         [0006]    An aspect of the present invention involves a magnetic detachable embolization apparatus for embolizing an aneurysm of a blood vessel. The apparatus includes an element adapted to be detachably connected to a distal portion of a catheter for insertion within an aneurysm of a blood vessel, the element being shaped to be retained within the aneurysm, and one or more magnets carried by the element to internally induce a magnetic field from within the aneurysm to control a magnetic field controllable embolic to embolize the aneurysm. The one or more magnets may be one or more permanent magnets or electromagnets.  
           [0007]    An additional aspect of the present invention involves a method for embolizing an aneurysm of a blood vessel. The method includes providing a magnetic-field controllable embolic at an aneurysm in a blood vessel, and internally inducing a magnetic field at the aneurysm site to control the magnetic-field controllable embolic to embolize the aneurysm.  
           [0008]    Other features and advantages of the invention will be evident from reading the following detailed description, which is intended to illustrate, but not limit, the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The drawings illustrate the design and utility of preferred embodiments of the present invention, in which similar elements are referred to by common reference numerals.  
         [0010]    [0010]FIG. 1 is a side-elevational view of an embodiment of a catheter that may be used with the magnetic detachable embolization apparatus.  
         [0011]    [0011]FIG. 2 is a side-elevational view of a distal portion of the catheter illustrated in FIG. 1 in a blood vessel with an embodiment of a magnetic detachable embolization apparatus shown disposed in an aneurysm.  
         [0012]    [0012]FIG. 3 is a side-elevational view of an additional embodiment of a magnetic detachable embolization apparatus.  
         [0013]    [0013]FIG. 4 is a side-elevational view of another embodiment of a magnetic detachable embolization apparatus with a polymer/magnetic-particle composite material surrounding an internal support.  
         [0014]    [0014]FIG. 5 is a side-elevational view of an embodiment of an external support surrounding a polymer/magnetic-particle composite material.  
         [0015]    FIGS.  6 - 8  are exemplary illustrations of how the magnetic properties of the elongate polymer/magnetic-particle composite material may vary.  
         [0016]    [0016]FIG. 9 is a side-elevational view of the distal portion of the catheter illustrated in FIG. 2 with the magnetic detachable embolization apparatus disposed therein in a retracted state.  
         [0017]    [0017]FIG. 10 is side-elevational view of a distal portion of a catheter with a further embodiment of a magnetic detachable embolization apparatus shown.  
         [0018]    [0018]FIG. 11 is side-elevational view of a still further embodiment of a magnetic detachable embolization apparatus shown. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    With reference to FIG. 1, an exemplary multi-section catheter  100  that may be used to deliver and deploy a magnetic detachable embolization apparatus  105 , which is constructed in accordance with an embodiment of the invention, at a targeted aneurysm  107  (FIG. 2) will now be described. Although the invention will be described in terms of aneurysm treatment, it may also be adaptable for endovascular occlusion in arteries, veins, vascular malformations, and arteriovenous fistulas. The invention may also be used for forming an occlusion in other areas of a mammalian body.  
         [0020]    The catheter  100  includes a distal section  110 , an intermediate section  120 , and a proximal section  130 . The sections decrease in flexibility from the proximal section  130  to the distal section  110 .  
         [0021]    The distal section  110  is very flexible and soft to allow deep penetration into the extraordinary convolutions of the neurological vasculature without trauma. The magnetic detachable embolization apparatus  105  is deployed from the distal section  110  of the catheter  100  at a distal end  135 . The distal section  110  may include one or more radio-opaque bands  140  to allow viewing of the position of the distal section under fluoroscopy.  
         [0022]    A luer assembly  150  at the proximal section  130  of the catheter  100  accomodates a core, utility, pusher, or guide wire  160 . The wire  160  may be made of any well-known guide wire material in the art such as stainless steel. The magnetic detachable embolization apparatus  105  may be attached to a distal end of the wire  160 . The luer assembly  150  may also include a fluid port for introducing and/or removing a magnetically controllable embolization substance and a power port  170  for connecting the catheter  100  to a power supply. The catheter  100  may also include any well-known steering assembly in the art for delivering the magnetic detachable embolization apparatus  105  to the targeted aneurysm  107 .  
         [0023]    With reference to FIG. 2, an embodiment of the magnetic detachable embolization apparatus  105  will now be described. The apparatus  105  includes one or more permanent Neodynium (NdFeB) or Samarium Cobalt (SmCo) magnets  200  attached to an element shaped to retain or secure the apparatus  105  within the aneurysm  107 . In the embodiment shown, the element is a multi-loop assembly  205  made of a shape memory material such as Nitinol™. The multi-loop assembly  205  may be a modified TriSpan™ coil sold by Target Therapeutics® of Freemont, Calif. The multi-loop assembly  205  preferably includes three wire wings or loops, a first wire loop  210 , a second wire loop  220 , and a third wire loop  230 . Although the assembly  205  is shown as having three wire loops, other numbers of loops may be used. The expanded wings or loops  210 ,  220 ,  230  of the multi-loop assembly  205  help to secure the device in the aneurysm  107  once the assembly  205  is deployed in the aneurysm  107 .  
         [0024]    The multi-loop assembly  205  is coupled to the wire  160  by a detachment mechanism  250 . Examples of detachment mechanisms that may be used include a mechanical detachment mechanism such as that described in U.S. Pat. No. 5,250,071 (“the &#39;71 patent”) to Palermo (or the mechanical detachment mechanism described below with respect to FIG. 5) and an electrolytic detachment mechanism such as those described in U.S. Pat. No. 5,122,136 (“the &#39;136 patent”) to Guglielmi, et al. and U.S. Pat. No. 6,123,714 (“the &#39;714 patent) to Gia, et al. The &#39;71, &#39;136, and &#39;714 patents are incorporated by reference as though set forth in full. Preferably, an electrolytic detachment mechanism similar to those described in the &#39; 136  patent or the &#39;714 patent is used. An electrolytic detachment mechanism includes an electrolytic, sacrificial joint that separates when a small electric current is applied therethrough. The &#39;136 patent describes a soldered electrolytic, sacrificial joint and the &#39;714 patent describes a solderless electrolytic, sacrificial joint.  
         [0025]    Although the magnetic detachable embolization apparatus  105  has been described as having a multi-loop configuration, in alternative embodiments, the apparatus may include other configurations. For example, with reference to FIG. 3, the magnetic detachable embolization apparatus  105  may be comprised of a generally spherical, basket assembly  305 . The basket assembly  305  includes a plurality of arced wire splines  310 ,  320 ,  330 ,  340 ,  350 ,  360  attached at distal ends to a permanent Neodynium (NdFeB) or Samarium Cobalt (SmCo) magnet  200  and attached at proximal ends to a detachment mechanism  250 . One or more of the splines  310 ,  320 ,  330 ,  340 ,  350 ,  360  may carry one or more magnets  200 .  
         [0026]    The apparatus  105  may come in a variety of sizes to accommodate different size aneurysms and/or a variety of configurations to accomodate aneurysms having different shapes.  
         [0027]    With reference to FIG. 4, although the apparatus  105  has been shown as having a single magnet  200 , the apparatus  105  may carry multiple magnets. For example, the multi-loop assembly  205  may be coated with a polymer and magnetic-particle composite material  362  having multiple tiny magnetic particles therein. The composite material  362  allows enhanced control over magnetic liquid embolics by distribution of the tiny magnetic particles over the entire length of the assembly  205 . The composite material  362  also gives the apparatus  105  more flexibility than the embodiment shown in FIG. 2. The multi-loop assembly  205  serves as an internal support  364  that imparts shape memory to the apparatus  105 .  
         [0028]    With reference to FIG. 5, in an alternative embodiment, an external support  366  may impart shape memory to the apparatus  105 . For example, the external support  366  may be a platinum coil that surrounds the polymer/magnetic-particle composite material  362 .  
         [0029]    In a further embodiment, the apparatus  105  may include a polymer/magnetic-particle composite material  362  without an internal support  364  or external support  366 . The composite material  362  may include a shape memory polymer in the composite without other support. When deployed, the composite material  362  forms an element shaped to retain or secure the apparatus  105  within the aneurysm.  
         [0030]    In a still further embodiment, the apparatus may include the composite material  362  where the composite material  362  has no other support and does not include a shape memory.  
         [0031]    With reference to FIGS.  6 - 8 , the magnetic properties of the composite material  362  may be varied such that the apparatus  105  exhibits single or multiple magnetic dipoles. FIG. 6 illustrates an embodiment of the composite material  362  where the material  362  includes single dipoles. FIGS. 7 and 8 illustrate embodiments of the composite material  362  where the material  362  includes multiple dipoles. In FIG. 7, the composite material  362  has multiple dipoles aligned with the longitudinal axis of the material  362 . In FIG. 8, the composite material  362  has multiple dipoles aligned transversely with respect to the longitudinal axis of the material  362 .  
         [0032]    With reference specifically to FIGS. 2 and 9, the magnetic detachable embolization apparatus  105  will now be described in use. The catheter  100  is introduced into the vasculature of a patient via a cannula or introducer sheath and snaked through the vasculature of the patient to the targeted aneurysm  107  by any well-known method in the art. X-ray, fluoroscopy or other well-know visualization techniques may be used to assist the physician in directing the catheter  10  to the targeted aneurysm  107 . The catheter  100  may be introduced over a guide wire such as the guide wire  106  to facilitate delivery of the catheter  100  to the targeted aneurysm  107 . FIG. 9 illustrates the magnetic detachable embolization apparatus  105  in a retracted or un-deployed state, which is how the apparatus  105  may be oriented as the catheter  100  is being delivered to the targeted aneurysm  107 , before the apparatus  105  is deployed at the aneurysm site. The wire loops  210 ,  220 ,  230  are folded together so as to fit inside the distal portion  110  of the catheter  100 . The distal end  135  of the catheter  100  may be positioned at the aneurysm site adjacent a neck  385  of the aneurysm  107 , at the neck  385  of the aneurysm  107 , or within the aneurysm  107 .  
         [0033]    Once the distal end  135  of the catheter  100  is delivered to the aneurysm  107 , the apparatus  105  may be deployed within the aneurysm  107 . This may be accomplished by advancing the guide wire  250  distally through the catheter  100 . Preferably, the apparatus  105  has a pre-shaped memory so that the apparatus  105  will automatically deploy into the configuration shown in FIG. 2 when the apparatus  105  is advanced into the aneurysm  107 . In an alternative embodiment, the catheter  100  may include a sheath that is retracted to deploy the apparatus  105 . The apparatus  105  is preferably positioned in the aneurysm  107  so that the first wire loop  210  is positioned near a top center of a dome  390  of the aneurysm  107 . The wire loops  210 ,  220 ,  230  hold the apparatus  105  securely within the aneurysm  107 .  
         [0034]    Next, a magnetically controllable embolic, preferably an acrylic, iron-containing glue, is delivered to the aneurysm  107  via the catheter  100 . In an alternative embodiment, the embolic may have a different composition. The one or more permanent magnets  200  (or the polymer/magnetic-particle composite material  362  illustrated in FIG. 4- 8 ) of the apparatus  105  internally attracts, from within the  20  aneurysm  107 , the iron-containing embolic to the magnet(s)  200 /material  362 , filling the aneurysm  107 . The apparatus  105  may be detached from the wire  160  using the detachment mechanism  250  before or after the embolic is delivered to the aneurysm  107 . Further, if the apparatus  105  is detached from the wire  160  after the embolic is delivered to the aneurysm  107 , the apparatus  105  may be detached from the wire  160  after the embolic has sufficiently hardened or polymerized in the aneurysm  107 .  
         [0035]    The apparatus  105  is left in the aneurysm  107  and the catheter  100  is withdrawn from the patient&#39;s body. The permanent magnet(s)  200 /composite material  362  may continue to attract the iron-containing embolic to the magnet(s)  200  and within the aneurysm  107  after the catheter  100  is withdrawn.  
         [0036]    Although the magnetic detachable embolization apparatus  105  has been described as including a permanent magnet(s)  200 /composite material  362 , in alternative embodiments, the detachable embolization apparatus may include an electromagnet that is used to internally induce a magnetic field within the aneurysm  107  for embolizing the aneurysm  107  by running electrical current through the electromagnet.  
         [0037]    For example, with reference to FIG. 10, an embodiment of an electromagnetic detachable embolization apparatus  500  is shown. The apparatus  500  includes a curvilinear, toroid-shaped electromagnet  503  aligned with an axis  510  of the catheter  100  and a pair of wire loops  520  to help secure the apparatus  500  within the aneurysm  107 . The electromagnet  503  and the wire loops  520  are coupled to a cylindrical base  530  that is configured to be slidably disposed within a distal portion  540  of the catheter  100 . The cylindrical base  530  includes an outer cylindrical conductive surface  560  and an inner cylindrical conductive surface  570 .  
         [0038]    The electromagnet  503  includes a lead wire  505 , a return wire  515 , a main wire  525 , an insulated structural support wire  535 , a first insulating separator  545 , and a second insulating separator  555 . The lead wire  505  is electrically coupled to the inner cylindrical conductive surface  570  of the cylindrical base  530  and the return wire  515  is electrically coupled to the outer cylindrical conductive surface  560  of the cylindrical base  530 . The main wire  525  has a lead end  565  electrically connected to the lead wire  505  and a return end  575  electrically connected to the return wire  515 . The first insulating separator  545  connects the lead wire  505  to a first portion  585  of the insulated structural support wire  535  and the second insulating separator  555  connects the return wire  515  to a second portion  595  of the insulated structural support wire  535 . The main wire  525  includes numerous coils  600  that together form the curvilinear, toroid shape of the electromagnet  503 .  
         [0039]    The cylindrical base  530  will now be described in more detail. The outer cylindrical conductive surface  560  of the cylindrical base  530  may be electrically coupled to the return wire  515  via a cylinder lead wire  625  located inside the cylinder  530 . Alternatively, the return wire  515  may be coupled directly to the outer cylindrical conductive surface  560  of the cylindrical base  530 . The inner cylindrical conductive surface  570  is electrically coupled to the lead wire  505  and includes internal threads  635  threadably engageable with external threads  640  of the wire  160 . A proximal end  645  of the wire  160  is connected to a lead  650  of a current supply  655 . This threaded coupling forms a mechanical detachment mechanism  642 . The inner cylindrical conductive surface  570  is preferably integral with the the outer cylindrical conductive surface  560  of the cylindrical base  530  so as not to allow relative rotation therebetween. Insulating material may be located between the inner cylindrical conductive surface  570  and the outer cylindrical conductive surface  560 . This insulating material may partially or completely fill any space inside the cylindrical base  530 .  
         [0040]    The catheter  100  may include a braided conducting wire  660  in the catheter wall. A proximal end  665  of this wire  660  may be electrically coupled to the current supply  655 . A distal end  667  of the braided wire  660  is electrically coupled to a catheter contact  670 . The catheter contact  670  is cylindrical and is located at the distal end of the catheter  100 . The catheter contact  670  slidably receives the outer cylindrical surface  560  of the cylindrical base  530  for electrical communication therewith. The sliding friction of this connection must be great enough to hold the cylindrical base  530  in place when the wire  160  is unscrewed from the internal threads  635  of the cylindrical base  530 , but small enough to allow the catheter  100  to be withdrawn from the aneurysm site without retaining the apparatus  500 . In an alternative embodiment, the wire  660  and contact  670  may be incorporated within the core wire  160 .  
         [0041]    In use, the catheter  100  is snaked through the vasculature of the patient to a targeted aneurysm  107  with the electromagnetic detachable embolization apparatus  500  collapsed within the distal portion  540  of the catheter  100 . The apparatus  500  is deployed within the aneurysm  107  so that the electromagnet  503  is positioned near a top center of a dome  390  of the aneurysm  107 . The wire loops  520  hold the apparatus  500  securely within the aneurysm  107 . Current supplied by the power source  655  flows through the electromagnet  503 , electromagnetically and internally inducing a magnetic field in the aneurysm  107 . Next, the a magnetically controllable embolic is delivered to the aneurysm  107  via the catheter  100 . The electromagnet  503  of the apparatus  500  attracts the iron-containing embolic to the electromagnet  503 , filling the aneurysm  107 . Once the aneurysm  107  is filled a sufficient amount and the embolic has hardened or polymerized a sufficient amount, the distal end of the wire  160  is unscrewed from the internal threads  635  of the cylindrical base  530 . The catheter  100  is withdrawn from the patient&#39;s body and the apparatus  500  is left impregnated in the hardened embolic, within the aneurysm  107 .  
         [0042]    Although the electromagnet  503  has been described above as having a toroidal, curvilinear configuration, in alternative embodiments, the electromagnet may have different configurations.  
         [0043]    For example, with reference to FIG. 11, an embodiment of a linear electromagnet  700  is shown. The electromagnet  700  includes a lead wire  705 , a return wire  715 , a main coiled wire  725 , an insulated structural support wire  735 , a first insulating separator  745  that isolates the lead wire  705  from the support wire  735 , and a second insulating separator  755  that isolates the return wire  715  from the support wire  735 . Otherwise, the electromagnetic detachable embolization apparatus  500  is the same as that illustrated in FIG. 10.  
         [0044]    The above-described embodiments of the invention internally induce a magnetic field, from within the aneurysm, to embolize the aneurysm with a magnetically-directable embolic. This eliminates the needs for a cumbersome and expensive superconducting electromagnetic device or large permanent magnet such as those used for Stereotaxis procedures and produces a stronger and more efficient magnetic field at the point of interest than that produced by such devices.  
         [0045]    While embodiments and applications of this invention have been shown and described, it would be apparent to those in the field that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.