Abstract:
A magnetic embolization apparatus for embolizing an aneurysm of a blood vessel includes a catheter with a distal portion, and a permanent magnet and an electromagnet carried by the distal portion to internally induce a magnetic field in the aneurysm to control a magnetic field controllable embolic to embolize the aneurysm. A related method of embolizing an aneurysm of a blood vessel includes delivering a magnetic-field controllable embolic into an aneurysm, and simultaneously inducing a magnetic field in the aneurysm with a permanent magnet and an electromagnet 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 embolizing an 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 prcedures 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 embolization apparatus for embolizing an aneurysm of a blood vessel. The magnetic embolization apparatus includes a catheter with a distal portion, and a permanent magnet and an electromagnet carried by the distal portion to internally induce a magnetic field in the aneurysm to control a magnetic field controllable embolic to embolize the aneurysm.  
           [0007]    Implementations of the aspect of the invention described immediately above may include one or more of the following. The electromagnet is adapted to induce a magnetic field in a first direction to strengthen a magnetic field induced by the permanent magnet to embolize the aneurysm and in a second direction to counteract the magnetic field induced by the permanent magnet to assist in withdrawing the catheter from the aneurysm without removing any embolic. The distal portion includes a sealed tip to prevent a magnetic field controllable embolic from being drawn into the catheter. The permanent magnet is located circumferentially outside or inside the electromagnet. The catheter includes a wall with the permanent magnet and electromagnet located therein. A guide wire is slidably disposed in the catheter and carries the permanent magnet. The catheter includes a lumen that carries the permanent magnet.  
           [0008]    Another aspect of the invention involves a method of embolizing an aneurysm of a blood vessel. The method includes delivering a magnetic-field controllable embolic into an aneurysm, and simultaneously inducing a magnetic field in the aneurysm with a permanent magnet and an electromagnet to embolize the aneurysm.  
           [0009]    Implementations of the aspect of the invention described immediately above may include one or more of the following. A catheter includes a distal portion with the permanent magnet and the electromagnet located therein, and the step of simultaneously inducing a magnetic field in the aneurysm includes simultaneously inducing a magnetic field in the aneurysm with the permanent magnet and the electromagnet of the catheter to induce the magnetic filed in the aneurysm. The method further includes the steps of using the electromagnet to induce a magnetic field in a first direction to strengthen a magnetic field induced by the permanent magnet to embolize the aneurysm and in a second direction to counteract the magnetic field induced by the permanent magnet to assist in withdrawing the catheter from the aneurysm without removing any embolic. A guide wire is slidably disposed in the catheter and carries the permanent magnet, and the method further includes the step of introducing the permanent magnet into the aneurysm with the guide wire. The step of delivering a magnetic-field controllable embolic into the aneurysm is done with a second, separate microcatheter.  
           [0010]    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  
       [0011]    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.  
         [0012]    [0012]FIG. 1 is a side-elevational view of an embodiment of a catheter that may be used with the magnetic embolization apparatus.  
         [0013]    [0013]FIG. 2 is a cross-sectional view of a distal portion of the catheter illustrated in FIG. 1 in a blood vessel with an embodiment of the magnetic embolization apparatus shown disposed in an aneurysm.  
         [0014]    [0014]FIG. 3 is a cross-sectional view of a distal portion of a catheter with an additional embodiment of a magnetic embolization apparatus shown.  
         [0015]    [0015]FIG. 4 is a cross-sectional view of a distal portion of a catheter including a further embodiment of a magnetic embolization apparatus shown.  
         [0016]    [0016]FIG. 5 is a cross-sectional view of a distal portion of a catheter including a still further embodiment of a magnetic embolization apparatus shown. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    With reference to FIG. 1, an exemplary multi-section catheter  100  that may be used to deliver a magnetic 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. The magnetic embolization apparatus  105  induces a magnetic field in the aneurysm  107  to draw and retain a magnetically controllable embolic in the aneurysm  107 . 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.  
         [0018]    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 .  
         [0019]    The distal section or portion  110  is very flexible and soft to allow deep penetration into the extraordinary convolutions of the neurological vasculature without trauma. The magnetic embolization apparatus  105  is located in 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 or markers  140  to allow viewing of the position of the distal section under fluoroscopy.  
         [0020]    A luer assembly  150  at the proximal section  130  of the catheter  100  may accomodate a pusher, core, 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 luer assembly  150  may also include a fluid port  165  for connecting a fluid supply for introducing and/or removing a magnetically controllable embolic and a power port  170  for connecting the catheter  100  to a power supply. The magnetically controllable embolic may be delivered to the aneurysm site with a second, separate microcatheter (not shown) The catheter  100  may also include any well-known steering assembly in the art for delivering the magnetic embolization apparatus  105  to the targeted aneurysm  107 .  
         [0021]    With reference to FIG. 2, an embodiment of the magnetic embolization apparatus  105  will now be described. The apparatus  105  includes a coiled solenoid or induction electromagnet  210  located in a wall  215  of the catheter body, in the distal portion  110  of the catheter  100 . Electrical current may be supplied to the electromagnet  210  by a power source  220  via a lead wire  230  and returned by a return wire  240  to induce a first magnetic field. Polarity through the electromagnet  210  may be reversed to induce a second magnetic field in an opposite direction from the first magnetic field. A ferrous filling layer or permanent magnet layer  260  may be located in the catheter wall  215 , in the distal portion  110  of the catheter  100 . The layer  260  may be used to help generate a stronger magnetic field at the end of the catheter  100  and/or help reverse the magnetic field to remove the catheter  100  at the end of the procedure. A sealed tip or plug  270  may be located at the distal end  135  of the catheter  110  to prevent the ferrous polymer from entering the catheter  110 . The plug  270  is preferably made of a non-ferrous material. In an alternative embodiment, the plug  270  may be made of a ferrous material.  
         [0022]    The magnetic 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-known visualization techniques may be used to assist the physician in directing the catheter  100  to the targeted aneurysm  107 . The distal end  135  of the catheter  100  may be positioned at the aneurysm site adjacent a neck  280  of the aneurysm  107 , at the neck  280  of the aneurysm  107 , or within the aneurysm  107 . Preferably, the distal end  135  of the catheter  100  is positioned into the aneurysm  107 , near a dome  290  of the aneurysm  107 .  
         [0023]    Next, a magnetically controllable embolic such as a ferrous polymer (e.g., acrylic, iron-containing glue) that hardens over time is delivered to the aneurysm  107  via a separate, second microcatheter (not shown). In an alternative embodiment, the embolic may have a different composition.  
         [0024]    The electromagnet  210  and ferrous filling/permanent magnet layer  260  are used to generate magnetic field lines  310  at the distal portion  110  of the catheter  100  for drawing and retaining the magnetically controllable embolic in the aneurysm  107  for embolization. The electromagnet  210  is actuated by supplying current by the power source  220  through the lead wire  230  to the electromagnet  210 . The ferrous filling layer or permanent magnet layer  260  may help in inducing the magnetic field lines  310  for drawing and retaining the ferrous polymer in the aneurysm  107 . The combined magnetic fields induced by the electromagnet  210  and the permanent magnet  260  provide sufficient attractive force for drawing and maintaining the magnetically controllable embolic in the aneurysm  107  for embolization purposes. The strength of the magnetic field  310  induced by the electromagnet  210  may be controlled by varying the power supplied to the electromagnet  210 .  
         [0025]    If the layer  260  is a ferrous filling layer, magnetic field  310  may be terminated after the embolic has hardened or polymerized a sufficient amount, and the catheter  100  may be withdrawn from the aneurysm site. If the layer  260  is a permanent magnet layer, the polarity of the electromagnet  210  may be reversed, causing opposite magnetic field lines  315  to counteract or cancel out the magnetic field  310  induced by the permanent magnetic layer  260  so that the catheter  100  can be withdrawn from the aneurysm site without removing any of the embolic from the anuerysm  107 .  
         [0026]    The electromagnet  210  may also be used to retrieve cured magnetically controllable embolic that may have escaped the aneurysm  107 .  
         [0027]    With reference to FIG. 3, a magnetic embolization apparatus  350  constructed in accordance with an additional embodiment of the invention and method of use is the same as that described above with respect to FIG. 2 for the magnetic embolization apparatus  105 , except the electromagnet  210  is located circumferentially inside of the ferrous filling layer or permanent magnet layer  260  in the catheter wall  215 . Locating the electromagnet  210  circumferentially inside of the ferrous filling layer or permanent magnet layer  260  helps to enable a stronger magnetic field in the aneurysm  107  for drawing and holding the embolic in the aneurysm  107  during embolization or for cancelling out a possible magnetic field  310  generated by a permanent magnet layer  260  for removing the catheter  100  without removing any of the embolic from the anuerysm  107 .  
         [0028]    With reference to FIG. 4, a magnetic embolization apparatus  400  constructed in accordance with another embodiment of the invention will now be described. The apparatus  400  is part of a catheter  410  having a lumen  420  defined by a lumen wall  430 . The apparatus  400  includes a coiled solenoid or induction electromagnet  460  located in the lumen wall  430 , in a distal portion  470  of the catheter  410 . A guide wire  480 , which may be the same as the guide wire  160  described above, may be slidably disposed within the lumen  420 . At least a distal portion  490  of the guide wire  480  includes a ferrous portion or permanent magnet  500 .  
         [0029]    In use, the magnetic embolization apparatus  400  is snaked through the patient&#39;s vasculature to the targeted aneurysm site. The ferrous polymer is delivered to the aneurysm  107  through a separate, second microcatheter. Magnetic field lines  510  induced from the ferrous portion or permanent magnet  500  cause the ferrous polymer to be drawn into and retained within the aneurysm  107 . The ferrous portion or permanent magnet  500  may be maintained within the distal portion  470  of the catheter  410  or may be deployed from the catheter  410 , into the aneurysm  107  for embolization purposes. To remove the catheter  410  from the aneurysm  107 , the solenoid  460  may be actuated to induce a magnetic field that overcomes, counteracts, or cancels out the magnetic field  510  of the ferrous portion or permanent magnet  500 .  
         [0030]    In an alternative embodiment, the solenoid  460  may be actuated to create, in conjunction with the magnetic field  510  induced from the ferrous portion or permanent magnet  500 , a stronger magnetic field for drawing and retaining the ferrous polymer in the aneurysm  107 . To remove the catheter  410  from the aneurysm  107 , the polarity through the solenoid  460  may be reversed to overcome, counteract, or cancel out the magnetic field of the ferrous portion or permanent magnet  500 .  
         [0031]    With reference to FIG. 5, a magnetic embolization apparatus  600  constructed in accordance with a further embodiment of the invention will now be described. The magnetic embolization apparatus  600  is similar to the magnetic embolization apparatus  400  described above, except the guide wire  480  is replaced with a ferrous portion or permanent magnet  610 . A plug  620  may be located at a distal end  630  of the lumen  420  to prevent the ferrous polymer from entering the lumen  420 .  
         [0032]    The method of use for the magnetic embolization apparatus  600  is the same as that described above with respect to the magnetic embolization apparatus  400 , except the ferrous portion or permanent magnet  610  of the apparatus  600  can not be deployed into the aneurysm  107  apart from the catheter  410 .  
         [0033]    Thus, the magnetic embolization apparatus embodiments described above include a permanent magnet combined with an electromagnet to induce a strong enough magnetic field to draw and maintain the magnetically controllable embolic in the aneurysm  107  for embolization purposes. The polarity of the electromagnet may be reversed to create a magnetic field that counteracts the magnetic field of the permanent magnet to facilitate withdrawal of the catheter from the aneurysm site without removing any of the embolic.  
         [0034]    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.