Abstract:
Devices, systems and methods are provided for performing implantation procedures in a desired area of the body. Systems include embodiments of medical implants that include scaffold and inflatable portions and delivery systems to position and release the medical implants at a target location within the body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Prov. Ser. 61/525,356 filed Aug. 19, 2011 which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The field of intralumenal therapy for the treatment of vascular disease states has for many years focused on the use of many different types of therapeutic devices. While it is currently unforeseeable that one particular device will be suitable to treat all types of vascular disease states it may however be possible to reduce the number of devices used for some disease states while at the same time improve patient outcomes at a reduced cost. To identify potential opportunities to improve the efficiency and efficacy of the devices and procedures it is important for one to understand the state of the art relative to some of the more common disease states. 
     For instance, one aspect of cerebrovascular disease in which the wall of a blood vessel becomes weakened. Under cerebral flow conditions the weakened vessel wall forms a bulge or aneurysm which can lead to symptomatic neurological deficits or ultimately a hemorrhagic stroke when ruptured. Once diagnosed a small number of these aneurysms are treatable from an endovascular approach using various embolization devices. These embolization devices include detachable balloons, coils, polymerizing liquids, gels, foams, stents and combinations thereof. 
     Detachable balloons were some of the earliest embolization devices used to treat aneurysms. Under fluoroscopic guidance these balloons were positioned within the aneurysm, inflated using a radio-opaque fluid and subsequently detached from their delivery mechanism. There were numerous drawbacks encountered while using these devices such as difficulty in guiding the devices to the treatment site due to size and shape, difficulties in placing the devices within the aneurysm due to the geometry of the balloons relative to the aneurysm geometry, excessive forces generated during detachment the balloons from the delivery system, dislodging of previously place balloons and delayed deflation of the detached balloons. Examples of various detachable balloon systems attempting to address some of the aforementioned drawbacks are disclosed in U.S. Pat. No. 3,834,394 to Hunter entitled, “Occlusion Device and Method and Apparatus for Inserting the Same”, U.S. Pat. No. 4,085,757 to Pevsner entitled, “Miniature Balloon Catheter Method and Apparatus, U.S. Pat. No. 4,327,734 to White Jr. entitled, “Therapeutic Method of Use for Miniature Detachable Balloon” U.S. Pat. No. 4,364,392 to Strother entitled “Detachable Balloon Catheter”, U.S. Pat. No. 4,402,319 to Handa, entitled, “Releasable Balloon Catheter”, U.S. Pat. No. 4,517,979 to Pecenka, entitled, “Detachable Balloon Catheter”, U.S. Pat. No. 4,545,367 to Tucci entitled, “Detachable Balloon Catheter and Method of Use”, U.S. Pat. No. 5,041,090 to Scheglov entitled, “Occluding Device” and U.S. Pat. No. 6,379,329 to Naglreiter entitled, “Detachable Balloon Embolization Device and Method.” Although the presented detachable balloon systems and improvements are numerous, few have been realized as commercial products for aneurysm treatment largely due to an inability to address a majority of the previously mentioned drawbacks. 
     The most widely used embolization devices are detachable embolization coils. These coils are generally made from biologically inert platinum alloys. To treat an aneurysm, the coils are navigated to the treatment site under fluoroscopic visualization and carefully positioned within the dome of an aneurysm using sophisticated, expensive delivery systems. Typical procedures require the positioning and deployment of multiple embolization coils which are then packed to a sufficient density as to provide a mechanical impediment to flow impingement on the fragile diseased vessel wall. Some of these bare embolization coil systems have been describe in U.S. Pat. No. 5,108,407 to Geremia, et al., entitled, “Method And Apparatus For Placement Of An Embolic Coil” and U.S. Pat. No. 5,122,136 to Guglielmi, et al., entitled, “Endovascular Electrolytically Detachable Guidewire Tip For The Electroformation Of Thrombus In Arteries, Veins, Aneurysms, Vascular Malformations And Arteriovenous Fistulas.” These patents disclose devices for delivering embolic coils at predetermined positions within vessels of the human body in order to treat aneurysms, or alternatively, to occlude the blood vessel at a particular location. Many of these systems, depending on the particular location and geometry of the aneurysm, have been used to treat aneurysms with various levels of success. One drawback associated with the use of bare embolization coils relates to the inability to adequately pack or fill the aneurysm due to the geometry of the coils which can lead to long term recanalization of the aneurysm with increased risk of rupture. 
     Some improvements to bare embolization coils have included the incorporation of expandable foams, bioactive materials and hydrogel technology as described in the following U.S. Pat. No. 6,723,108 to Jones, et al., entitled, “Foam Matrix Embolization Device”, U.S. Pat. No. 6,423,085 to Murayama, et al., entitled, “Biodegradable Polymer Coils for Intraluminal Implants” and U.S. Pat. No. 6,238,403 to Greene, et al., entitled, “Filamentous Embolic Device with Expansible Elements.” While some of these improved embolization coils have been moderately successful in preventing or reducing the rupture and re-rupture rate of some aneurysms, the devices have their own drawbacks. For instance, in the case of bioactive coils, the materials eliciting the biological healing response are somewhat difficult to integrate with the coil structure or have mechanical properties incompatible with those of the coil making the devices difficult to accurately position within the aneurysm. In the case of some expandable foam and hydrogel technology, the expansion of the foam or hydrogel is accomplished due to an interaction of the foam or hydrogel with the surrounding blood environment. This expansion may be immediate or time delayed but is generally, at some point, out of the control of the physician. With a time delayed response the physician may find that coils which were initially placed accurately and detached become dislodged during the expansion process leading to subsequent complications. 
     For many aneurysms, such as wide necked or fusiform aneurysms the geometry is not suitable for coiling alone. To somewhat expand the use of embolization coils in treating some wide necked aneurysms, stent like scaffolds have been developed to provide support for coils. These types of stent like scaffolds for use in the treatment of aneurysms have been described in U.S. Pat. No. 6,605,111 to Bose et al., entitled, “Endovascular Thin Film Devices and Methods for Treating Strokes” and U.S. Pat. No. 6,673,106 to Mitelberg, et al., entitled, “Intravascular Stent Device”. While these stent like devices have broadened the types of aneurysms amenable to embolization therapy, utilization of these devices in conjunction with embolization devices is technically more complex for the physician, may involve more risk to the patient and have a substantial cost increase for the healthcare system. 
     To further expand the types of aneurysm suitable for interventional radiological treatment, improved stent like devices have been disclosed in U.S. Pat. No. 5,824,053 to Khosravi et al., entitled, “Helical Mesh Endoprosthesis and Method”, U.S. Pat. No. 5,951,599 to McCrory, entitled, “Occlusion System for the Endovascular Treatment of and Aneurysm” and U.S. Pat. No. 6,063,111 to Hieshima et al., entitled, “Stent Aneurysm Treatment System and Method.” When placed across the neck of an aneurysm the proposed stent like devices purport to have a sufficient density through the wall of the device to reduce flow in the aneurysm allowing the aneurysm to clot, while at the same time having a low enough density through the wall to allow small perforator vessels adjacent to the aneurysm to remain patent. Stent devices of this nature while having the potential to reduce treatment costs have not been realized commercially due to the difficulty in manufacturing, reliability in delivering the devices to the treatment site and an inability to properly position the more dense portion of the stent device accurately over the neck of the aneurysm. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward a medical implant system for use in placing a medical implant at a preselected site within the body of a mammal. In accordance with one aspect of the present invention there is provided an embolization system for use in a mammal. The embolization system includes an elongate flexible delivery system coupled to an embolization device. The elongate filamentous or filament like embolization device comprises an elongate embolic coil member coupled to an expandable embolic balloon member. The embolization device generally resembles a long flexible strand having a generally elongated linear configuration when delivered through the lumen of a catheter and is capable of folding upon itself during placement at a target site in the body. The delivery system includes an elongate tubular filling member positioned within the lumen of an elongate tubular positioning member both having proximal and distal ends and wherein the distal end of the filling member is removably coupled to the embolic balloon member and adapted to provide fluid access to the interior of the balloon member. A valve member (normally biased closed) is included with the balloon member such that when sufficient fluid has been delivered to expand the balloon member to a desired volume, the tubular filling member may be uncoupled from the balloon member thereby allowing the valve member to seal the balloon member and maintain the balloon member inflation. 
     In accordance with another aspect of the present invention there is provided an elongate filamentous embolization device having an elongate filamentous scaffold portion and an expandable portion where the expandable portion includes an elongate balloon member and the scaffold portion takes the form of a radiopaque embolic coil. 
     In accordance with yet another aspect of the present invention there is provided a medical implant having a coating that includes bioactive materials. The bioactive materials may include bioerodible and or biodegradable synthetic materials. The coating may be preferably applied to the exterior of the device and further comprise one or more pharmaceutical substances or drug compositions for delivering to the tissues adjacent to the site of implantation, and one or more ligands, such as peptides which bind to cell surface receptors, small and/or large molecules, and/or antibodies or combinations thereof for capturing and immobilizing, in particular progenitor endothelial cells on the blood contacting surface of the device to promote healing. 
     In accordance with yet another aspect of the present invention there is provided an embolization device having an elongate filamentous scaffold portion and an expandable portion where the expandable portion includes a balloon member having a length that extends substantially the length of the embolic coil. The length of the scaffold portion or embolic coil is preferably greater than ten times the diameter of the inflated expandable portion or balloon member. Additionally, the balloon member may include regions along its length that limit or restrict expansion. 
     In accordance with still another aspect of the present invention, there is provided a method of deploying a medical implant within a portion of a vessel. The method comprises the steps of: positioning a catheter adjacent a target site; delivering an embolization system having an embolization device and delivery system to the target site; deploying the embolization device at the target site; inflating the embolization device with a fluid to increase the volume of a portion of the embolization device; releasing the embolization device from the delivery system; sealing the inflated portion of the embolization device; removing the delivery system and catheter from the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially sectioned view of an embodiment of a medical implant system of the present invention. 
         FIG. 2  is an enlarged partially sectioned view illustrating the distal portion of the medical implant system shown in  FIG. 1 . 
         FIG. 3A  is a partial cross-sectional view of an embolization device according to an embodiment of the present invention. 
         FIG. 3B  is a partial cross-sectional view of an embolization device according to another embodiment of the present invention. 
         FIG. 3C  is a partial cross-sectional view of an embolization device according to yet another embodiment of the present invention. 
         FIGS. 4 through 8  are partial section views illustrating a method of deploying a medical implant within an aneurysm according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Generally a medical implant deployment system of the present invention may be used to position an implant at a preselected site within the body of a mammal.  FIG. 1  generally illustrates embolization system  10  of the present invention which includes elongate catheter  20  having distal and proximal ends  22 ,  24  and lumen  25  extending therethrough. Proximal end  24  includes catheter hub  26  to facilitate access to lumen  25 . Additionally hub  26  includes a Luer connector to facilitate connections with accessory devices commonly used in interventional radiological procedures such as, rotating hemostatic valves. While not shown, the construction of catheter  20  may utilize known catheter technologies that incorporate braiding and or coiling using metallic or non-metallic reinforcing filamentous materials to provide high strength while maintaining catheter flexibility. The term “filamentous” as used herein may be used to describe an object a) composed of or containing filaments b) pertaining to or resembling a filament or c) bearing filaments. The aforementioned definition b) pertaining to or resembling a filament is understood to include general observations of filaments having a substantially longer length relative to its diameter. The incorporation of lubricious hydrophilic and or hydrophobic materials on the inner and or outer surface of the catheter and the application of tip markers are considered to be within the scope of known catheter construction techniques and suitable for uses herein described. Delivery system  30  having distal and proximal ends  32 ,  34  includes an outer tubular positioning member  36  having distal and proximal ends  38 ,  40  and an inner tubular filling member  42  having distal end  44 , aperture  45  and proximal end  46 . Filling member  42  includes hub  48  coupled to proximal end  46  to facilitate coupling to syringes or other fluid delivery sources. Delivery system  30  is positioned within lumen  25  of catheter  20  such that proximal end  34  extends proximal to catheter hub  26 .  FIG. 2  depicts embolization device  50 , having distal and proximal portions  52 ,  54 , which is coupled to delivery system distal end  32  in a removable fashion. Embolization device distal portion  52  includes a scaffold member that takes the form of elongate embolic coil  56  having a traumatic distal end  58 . Distal portion  52  of embolization device  50  includes joint member  59  which couples the distal end of embolic coil  56  to expandable balloon member  60 . Expandable balloon member  60  includes a proximal sealing valve  62  and a tubular retaining element  64  positioned around valve  62 . Distal end  44  of filing member  42  is positioned through sealing valve  62  such that aperture  45  is in fluid communication with balloon member  60 . Sealing valve  62  is formed of a resilient material and has a normally closed configuration such that when filling member distal end  44  is withdrawn from sealing valve  12  the sealing valve closes. The resiliency of sealing valve  62  provides a frictional engagement between the valve and distal end  44  of filling member  42 . Retaining element  64  preferably takes the form of a radiopaque shrink tubing or marker band to provide visibility under fluoroscopy of the proximal end of embolization device  50  and to restrict the expansion of sealing valve  62  thus providing increased frictional engagement between the sealing valve and filling member distal end  44 . Distal end  38  of pusher member  36  is positioned adjacent sealing valve  62  and retaining element  64 . Positioning member  36  is preferably formed of a thin walled metallic hypotube however catheter construction materials and techniques may also be suitable. Preferably, distal end  38  of pusher member  36  is flexible but resists axial elongation and compression and has an outer diameter close to the diameter of sealing valve  62 . Filling member  42  is also preferably formed of a thin walled metallic hypotube however catheter construction materials and techniques may also be suitable. 
     Embolic coil  56  is shown in  FIG. 2  adjacent to expandable balloon member  60  and more specifically in a preferred arrangement of embolization device  50 , at least a substantial portion of the length of coil  56  is positioned within the interior of balloon member  60 . In an alternative arrangement (not shown), a balloon member may have a length substantially comparable to the length of an embolic coil scaffold member, fixedly coupled to the coil however, the scaffold member is not substantially positioned within the interior of the balloon member. In this alternative arrangement, the balloon member and the scaffold member are side by side extending generally parallel to each other during delivery through a catheter lumen. 
       FIG. 3A  illustrates embolization device  50  where balloon member  60  has been expanded and sealing valve  62  is closed. Embolic coil  56  of embolization device  50  is typically formed from a helically coiled wire using suitable biocompatible materials such as platinum, nitinol, gold or stainless steel with platinum being a preferred material. The wire depicted in embolic coil  56  has a preferred cross-sectional geometry which is circular although other shapes such as “D”, rectangular and star are also contemplated. Scaffold members such as embolic coil  56  may take other suitable forms such as elongate braids or multi-filar winds. Embolic coil  56  is shown having a generally straight shape for convenience but preferably has a shape and size suited for a target location. Embolic coil  56  has a “primary” coil diameter that ranges from about 0.005 inches to about 0.050 inches and preferably ranges from about 0.008 inches to about 0.040 inches. The length of embolic coil  56  may vary widely and ranges from about 1 cm to about 150 cm with a preferred range of 2 cm to 80 cm. These coils may be formed into helices, spheres or other complex or convoluted shapes having a “secondary” coil diameter ranging from about 2 mm to 50 mm. The selection of the dimensions for a particular coil is dependent upon the dimensions and geometry of the target anatomical site. For example, to treat an aneurysm having a 7 mm diameter, the embolic coil  56  may preferably have a primary coil diameter in the range of 0.010 inches to 0.020 inches and a shape that is helical or generally spherical with a secondary diameter of about 7 mm to 8 mm dependent upon the stiffness of the coil. Embolization device  50  may also include modifications such as the addition of stretch resistance members to aid in delivery, surface texturing and or the addition of bioactive materials and therapeutic compounds as components or coatings to promote the healing response. Other shapes such as spirals and “hour glasses” may be suitable for other lumenal locations within the body. 
     An alternative embodiment of an embolization device is shown in  FIG. 3B  where embolization device  150  having balloon member  160  includes expansion resisting elements  172  and  174 . The expansion resisting elements restrict or limit portions of balloon member  160  from expanding during inflation. Expansion resisting elements  172  and  174  are preferably formed as tubular segments of shrink tubing that are positioned around portions of balloon member  160 . Alternatively, portions of balloon member  160  may be integrally secured to coil  156  to restrict expansion at that particular location. 
     Another alternative embodiment of an embolization device is shown in  FIG. 3C  where embolization device  250  having embolic coil  256  includes an elongate shaping wire  257  positioned within the lumen of coil  256 . The elongate shaping wire  257  is preferably formed of a resilient material such as nitinol and aids the coil in taking a shape. The shaping wire  257  may be free floating within the lumen of coil  256  or secured at various locations to provide increased stretch resistance. 
     Balloon member  60 , shown in an expanded configuration, may be formed of an elastomeric material such as silicone in a first preferred embodiment having a compliant balloon member and a non-elastomeric material such as polyethylene terephthalate (PET) in a second preferred embodiment having a non-compliant or semi-compliant balloon member. Suitable compliant balloon materials include other polymeric elastomers such as urethanes, polyether block amide (PEBAX) and synthetic rubbers including polyisoprene, nitrile, chloroprene, ethylene propylene diene rubber. Suitable non-compliant or semi-compliant balloon materials include polymers such as nylons, polyolefins and polytetrafluoroethylene (PTFE). Balloon member  60  may be formed by conventional techniques including extrusion and or molding of aforementioned polymers. For non-compliant or semi-compliant balloon members the wall thickness of the balloon member typically ranges from about 0.0001 inches to about 0.003 inches. For compliant balloon members the wall thickness of the balloon member typically ranges from about 0.0005 inches to about 0.006 inches. Embolic coil  56  is positioned within balloon member  60  and balloon member  60  has a length that extends along a substantial portion of the length embolic coil  56  and may include the entire length of embolic coil  56  as shown in  FIG. 3A . Additionally, balloon member  60  may be coated with lubricious hydrophilic and or hydrophobic materials to aid in delivery through lumen of the catheter. Balloon member  60  is preferably inflated with a low viscosity fluid  70  such as saline. Radiopaque fluids such as iodinated contrast solutions may also be suitable and provide the advantage of visibility during inflation. Balloon member  60  may also be inflated using radio-opacified fluids that transition from a liquid to a solid polymerizable or cross linkable solutions such as alginates, cyanoacrylates and monomers of hydroxyl-ethyl methacrylate (HEMA). 
     One important aspect of embolization devices according embodiments of the present invention that include an elongate filamentous scaffold member and an expandable balloon member is to provide stable volume filling of an anatomical target site greater than the volume filling that can be achieved by the filamentous scaffold alone. It is also advantageous in performing medical procedures that the delivery catheters utilized to deliver embolization devices according to embodiments of the present invention be comparable in size to the delivery catheters used when delivering conventional detachable embolic coil systems. As previously discussed, scaffold members such as embolic coils have a primary diameter, and a relationship between the inflated balloon member diameter and the primary diameter of the scaffold member has been determined to allow for the use of delivery catheters comparable in size to the delivery catheters used with conventional detachable coil systems. In a preferred embodiment having a non-compliant or semi-compliant balloon member the inflated balloon member maximum diameter is greater than 1.2 times the primary diameter of the scaffold and is preferably in the range of 1.5 to 4 times the primary scaffold diameter with a most preferred range of 1.7 to 3.5 times the primary scaffold diameter. 
       FIGS. 4 through 8  illustrate the method steps of using embolization system  10  to treat an aneurysm of a blood vessel. Embolization system  10  is inserted into blood vessel  300  and catheter  20  is moved to a position within vessel  300  where catheter distal end  22  is positioned within aneurysm  302  adjacent to aneurysm neck  304  ( FIG. 4 ). Embolization device  50  is inserted into the lumen of catheter  20  and has a generally linear configuration. Delivery system  30 , coupled to embolization device  50 , is advanced distally within catheter  20  such that embolic coil  56  begins to exit catheter lumen  25  and enter aneurysm  302 . Further advancement of delivery system  30  allows embolization device  50 , which is capable of folding upon itself, to take a shape within aneurysm  302  with embolic coil  56  forming a scaffold or framework supporting balloon member  60 . During delivery, the physician may retract and advance delivery system  30  to reposition embolic coil  56  into the desired scaffold geometry. Once embolization device  50  is properly positioned within aneurysm  302  ( FIG. 6 ), a fluid delivery source, such as a fluid filled syringe, is then coupled to filling member hub  48  (not shown). Fluid  70  is delivered to balloon member  60  via filling member  42  to inflate or expand balloon member  60  to a desired volume. It is preferable that fluid  70  is a radiopaque polymerizable liquid, so that the volume filling of balloon member  60  is readily identifiable under fluoroscopy ( FIG. 7 ). Upon achieving the desired filling of balloon member  60 , filling member  42  is retracted relative to pusher member  36 , withdrawing filling member distal end  44  from balloon member  60  thus uncoupling delivery system  30  from embolization device  50  which allows sealing valve  62  to close and seal. The closed sealing valve  62 , maintains the inflation of balloon member  60  and the scaffold created by embolic coil  56  retains balloon member  60  within aneurysm  302 . Delivery system  30  may then be removed from catheter  20  and the body. If the volume filling of the aneurysm is determined to be insufficient, the physician may deploy another embolization device into the aneurysm and fill to achieve the desired result, otherwise catheter  20  can be removed. 
     As is apparent, there are numerous modifications of the preferred embodiment described above which will become readily apparent to one skilled in the art. It should be understood that various modifications including the substitution of elements or components which perform substantially the same function in the same way to achieve substantially the same result may be made by those skilled in the art without departing from the scope of the claims which follow.