as may be seen in fig1 the present invention is directed to an implantable medical device such as a stent 10 . in the context of the present application a stent is viewed as a device for providing support or repair to a body lumen . such devices include balloon expandable as well as self expanding stents such as have been described above , as well as stent grafts , vena cava filters , and other similar devices . the stent 10 , of the present invention may be an existing stent which is modified to include magnetic properties or may be a new stent constructed with magnetic properties as provided herein . the present invention is directed to any stent which is characterized as including in at least a portion of the stent &# 39 ; s construction a predetermined quantity of a magnetic material or which has been rendered magnetic by any means . the inventive stent 10 disclosed herein may be made of any stent material known in the art including polymeric materials , metals , ceramics and composites . where the stent is made of metal , the metal may be stainless steel , elgiloy , tantalum or other plastically deformable metals . other suitable metals include shape - memory metals such as nitinol ™. the inventive stents may include suitable radiopaque coatings . for example , the stent 10 may be coated with gold or other noble metals or sputtered with tantalum or other metals . the stent 10 may also be made directly from a radiopaque material to obviate the need for a radiopaque coating or may be made of a material having a radiopaque inner core . the entire stent 10 , or selective portions thereof , may be manufactured from one or more magnetic materials . for example , a predetermined quantity of magnetite or an alloy thereof may be included in the construction of the stent 10 . other materials may be utilized to provide the desired magnetic properties . such materials may be temporary magnetic materials or permanent magnetic materials . some examples of suitable magnetic materials include , magnetic ferrite or ‘ ferrite ’ which is a substance consisting of mixed oxides of iron and one or more other metals , the heat treatment of the mixed oxides produces complex crystals with magnetic properties . an example ferrite material is : nanocrystalline cobalt ferrite , however other ferrite materials may be used . other magnetic materials which may be utilized in the construction of stent 10 include but are not limited to : ceramic and flexible magnetic materials made from strontium ferrous oxide which may be combined with a polymeric substance such as plastic , or rubber ; ndfeb ( this magnetic material may also include dysprosium ); smco ( samarium , cobalt ); and combinations of aluminum , nickel , cobalt , copper , iron , titanium as well as other materials . as indicated above , the beneficial nature of magnetism in healing and pain reduction is known but the mechanism which provides for these results is yet to be fully understood . however , it has been suggested that the magnetic field strength should be fairly strong in order to provide the beneficial effects desired . as a result , in the present invention , the magnet materials or magnetic properties of the stent preferably emit a magnetic field of between about 20 to 10 , 000 gauss and preferably between 400 and 2000 gauss . known stent materials such as nitinol and stainless steel may also be rendered sufficiently magnetic by subjecting the stent material to a sufficient electric and / or magnetic field . such a field may imbue the stent 10 , or a portion thereof with magnetic properties without the need to include the magnetic materials described above in the construction of the stent 10 . as may be seen in fig1 stents , such as the stent 10 presently depicted , typically are constructed of a plurality of interconnected struts and members 12 . by providing one or more of the interconnected members 10 with magnetic properties a portion of the stent is rendered magnetic . alternatively , if all of the members 12 are constructed with magnetic materials or rendered magnetic , the entire stent 10 may be provided with magnetic properties . it is understood that stent 10 is to be inserted into a body , and must therefore be biocompatible . unfortunately , many magnetic materials may not be sufficiently biocompatible to be suitable for use in stent construction . to avoid problems associated with non - biocompatible materials , where one or more members 12 are constructed , in whole or in part , from a magnetic material which is non - biocompatible , the member 12 or a portion thereof may be coated with a biocompatible coating 14 such as may be seen in fig2 . the entire stent 10 or portions thereof may be coated with coating 14 . biocompatible coatings for use with stents are well known , and an example of such a coating may be gold . however , any biocompatible coating may be used with the present invention . as may be seen in fig3 the stent 10 may be configured to include magnetic material within a portion 3 a of one or more of the interconnected members 12 . as depicted in the detailed fig3 a , at least one interconnected member may include one or more chambers 16 which has a portion of magnetic material 18 contained therein . the magnetic material 18 may be in solid or liquid form . where the stent 10 has members 12 which include chambers 16 , the members 12 are preferably constructed of a biocompatible material , thus alleviating the need for an additional coating such as previously discussed . rather than constructing specialized chambers for containing magnetic material or providing individual stent members with magnetic materials in their construction , as may be seen in fig4 the members 12 of stent 10 , may include one or more pores 20 . the pores 20 may be filled with magnetic material 18 , and then optionally coated with a biocompatible coating 14 . another means of providing a stent 10 with magnetic properties may be to coat the stent 10 or a portion thereof with a coating 22 which has magnetic properties , such as is shown in fig5 . such a coating may include magnetic materials such as are described above , or may be a known material which has been rendered magnetic through exposure to a magnetic and / or electric field of sufficient strength . in addition to being directed to the embodiments described above and claimed below , the present invention is further directed to embodiments having different combinations of the features described above and claimed below . as such , the invention is also directed to other embodiments having any other possible combination of the dependent features claimed below . the above examples and disclosure are intended to be illustrative and not exhaustive . these examples and description will suggest many variations and alternatives to one of ordinary skill in this art . all these alternatives and variations are intended to be included within the scope of the attached claims . those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto .
an implantable medical device for intra lumenal support of a body lumen wherein at least a portion of the implantable medical device comprises at least one magnetic material .