Patent Publication Number: US-2004044351-A1

Title: Mechanical occluding device

Description:
RELATED APPLICATIONS  
     [0001] This invention relates to provisional patent No. 60/406,280 filed on Aug. 27, 2002. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to mechanical occluding devices. More particularly, the present invention is directed to a vaso-occluding stent for occluding blood flow to a benign tumor or similar indication and is directed to a detachable balloon that could be used to occlude blood flow to a benign tumor or similar indication or for sealing an opening in the wall of a blood vessel or other percutaneous opening. The present invention is directed to a method for internally ligating vessels. The device and procedure could be used for occluding blood flow to a benign tumor, similar indication, or in support of vessel harvesting.  
       [0004] 2. Background  
       [0005] The recovery time for soft tissue surgery for stent placement is on average forty-seven days while the recovery time for catheteral placement is approximately eleven days. As catheteral procedures have improved and increased over the past decade, Interventional Radiology has developed as a specialized field of radiology in which the treatment of vascular and non-vascular diseases is accomplished through the use of small diameter catheters and the deployment of devices through small diameter catheters. Many of these catheteral procedures involve embolotherapy or hemostasis, which is a minimally invasive procedure that employs an embolic or blocking agent to a targeted vessel to inhibit blood flow to a tumor or similar indication. The present invention is classified as a mechanical occlusion device. Similar devices include balloons, coils, and clamps.  
       [0006] Detachable balloons are mechanical devices that are used for embolotherapy. These balloons can vary in size and shape, and are typically manufactured from either latex or silicone. Detachable balloons can be inflated and left in place to form a permanent blockage and can also be used to provide a temporary blockage to prevent blood loss during surgical procedures. Although the balloons are self-sealing, over time they can deflate and can even migrate causing a blockage in nearby blood vessels.  
       [0007] Ligation of a blood vessel is another means to provide blood flow occlusion. Unfortunately, the lengthy recovery from soft tissue surgery eliminates ligation as a viable means to provide temporary and in some cases permanent occlusion of blood vessels. Ideally, a percutaneous means of tying-off blood vessels is required to support interventional radiological procedures. The present invention is directed to a method for internally ligating vessels. The device and procedure could be used for occluding blood flow to a benign tumor, similar indication, or in support of vessel harvesting.  
       SUMMARY OF THE INVENTION  
       [0008] The vaso-occluding stent of the present invention can be used to occlude blood flow to a benign tumor or similar indication. By slowly occluding blood flow, the post-procedural complications associated with some forms of embolotherapy will be reduced. The vaso-occluding stent of the present invention is deployed through a percutaneous catheteral procedure. The vaso-occluding stent of the present invention is designed to be used in conjunction with currently existing stents, such as Bolton Medical&#39;s “Spiral Force” stent number 11-700-09. This Bolton Medical stent is 9 mm long and expands to a diameter of 2.5 to 4.0 mm. This Bolton Medical stent is compatible with Bolton Medical&#39;s “SF System” catheter, where the stent is preloaded onto a “Rapid Exchange PTCA Catheter.” The vaso-occluding stent of the present invention could also be used with the Bolton Medical&#39;s stent number 20-250-9. In addition, the vaso-occluding stent of the present invention can be resized to function with any similarly functioning stent.  
       [0009] To minimize recovery with human patients, the vaso-occluding stent of the present invention does not require soft tissue surgery. Instead, a catheteral procedure is utilized to implant the device. Since the targeted vessels are typically small diameter vessels, the design of the vaso-occluding stent of the present invention resembles a short, flexible, small diameter tube, and is capable of being expanded and anchored on the inner wall of a vessel. The vaso-occluding stent of the present invention absorbs fluid from the blood stream and expands over a predetermined period of time. The vaso-occluding stent of the present invention can be designed for complete closure or to occlude to a predetermined point to allow a reduced level of blood flow. By controlling the rate of occlusion, side effects from abrupt changes in blood flow are eliminated.  
       [0010] The vaso-occluding stent of the present invention includes the following four components: (1) an expandable stent similar in size and function to an angioplasty stent, (2) casein powder which acts as an expandable filler material (3) stainless steel foil to promote the uniform expansion of the casein and (4) a barrier film that encapsulates the stent, filler and foil.  
       [0011] Casein is a milk by-product and is used as a component of the stent of the present invention because it is inert and will expand over time to slowly occlude blood flow through the vessel. Casein has been incorporated into medical devices that are used in the field of veterinary medicine. The formation of an extra hepatic portosystemic shunt (EPSS) is a congenital condition in dogs and cats that is treated by surgically implanting an Ameroid Constrictor around the EPSS. The Ameroid Constrictor is composed of casein surrounded by a rigid, C-shaped stainless steel band and is placed around the outer wall of the EPSS. The casein material absorbs bodily fluids and slowly occludes the EPSS, thereby reducing the hypertension and promoting the replacement of blood vessels. Although casein is a viable material that has been proven in similar applications, any other inert material with similar solubility and mechanical properties would suffice.  
       [0012] The stent of the present invention can be manufactured either from stainless steel or from Elgiloy, an alloy of cobalt, chromium, nickel and iron. Elgiloy has superior mechanical properties as compared to stainless steel, and is preferred for use with the vaso-occluding stent of the present invention, because an Elgiloy stent will resist fracture or growth due to casein expansion.  
       [0013] Polypropylene (PP) has been selected as the material for the barrier film of the stent of the present invention. Additionally, other polymers such as Polytetrafluoroethylene (PTFE) and Polyethylene (PE) could be used provided their hydrophilic capacity is similar to that of PP. The hydrophilic capacity of all these materials could be modified/increased through the use of radiation grafting or surfactants.  
       [0014] The casein used in the stent of the present invention is pressure formed onto a thin sheet of stainless steel foil, and the casein/foil laminate is spirally wound. When the vaso-occluding stent of the present invention expands from the crimped state to the deployed state, the casein/foil laminate will unwind uniformly to reduce the risk of fracture to the casein. The outer surfaces of the casein, i.e. the two sides and the inner diameter, are first to absorb fluid and expand. The core of the formed casein is smaller in comparison to the outer surface, and therefore, the expansion rate is greater for the first initial period and slows from that point until occlusion is complete. Unlike the Ameroid Constrictor, the vaso-occluding stent of the present invention is placed into the blood stream using a percutaneous catheteral procedure. The stent, foil and casein are completely encapsulated by a micro-porous PP film that acts as (1) a barrier to retain any casein particles that could separate during deployment and (2) to control the rate at which the casein will expand. This feature allows the occlusion rate to be optimized to support specific medical conditions, patient recovery and to minimize mortality. The PP barrier is heat sealed to provide hermetic encapsulation of the components of the vaso-occluding stent of the present invention.  
       [0015] The vaso-occluding stent of the present invention will be fixed in place using a minimally invasive procedure. Placement and setting of the vaso-occluding stent will transmit minimal force to the targeted vessel. The vaso-occluding stent will slowly occlude blood flow through the vessel, either completely or to a predetermined degree. The vaso-occluding stent and all the components of the vaso-occluding stent will be biocompatible and non-biodegradable. By design, the vaso-occluding stent will minimize localized infection and thrombosis, and provide a means to identify the post-procedural location.  
       [0016] The detachable balloon of the present invention includes the following five components: (1) a preformed, expandable balloon manufactured from latex or silicone or another elastomer with similar properties, (2) a septum manufactured from an elastomer or another material with similar properties, to provide an ingress to the inside of the expandable balloon and a seal for the same, (3) a rigid band manufactured from stainless steel, Elgiloy, or a material with similar properties, to act as a sealing surface and to attach the septum to the expandable balloon and seal the device, (4) a crimp ring to fix and seal the balloon and septum to the rigid band assembly, and (5) a solution of saline and expandable particles, such as polyvinyl alcohol (PVA), gelatin foam, n-butyl-cyanoacrylate (nBCA) or a similar material, that are used to inflate the balloon.  
       [0017] Small PVA particles are commonly used to treat uterine fibroids. The surgical procedure for this condition begins by making a small incision near the groin to feed a catheter into the femoral artery. Using X-ray imaging, the catheter is directed near the target site. PVA particles are then injected through the catheter to the local area around the target site. The particles absorb fluid from the bloodstream to enlarge and form a blockage. The vessels at the target site are typically too small for the catheter to enter, and the PVA particles are therefore released some distance from the target site where they can migrate into other local vessels and cause unintended blockages. Also, the success of this form of embolic depends on the development of blood clotting around the PVA particles.  
       [0018] The detachable balloon of the present invention would be placed at a target site using a percutaneous catheteral procedure as described above. The present invention utilizes expandable particles as the media for inflating the expandable balloon. Once the device is in place, the solution is injected through the septum to completely expand the balloon and allow the balloon to anchor to the vessel wall. The balloon is sealed to eliminate the potential for deflation and migration. If a temporary blockage is required, the particles can be removed with a larger syringe, thereby deflating the balloon. Depending on the starting size of the PVA particles, the full expansion can be determined to correctly size a larger syringe for particle removal.  
       [0019] The detachable balloon of the present invention can also be filled with saline or gas, which is currently a typical practice in the medical device industry. For this alternative, the sealing integrity of the septum can be greatly improved by the addition of a diaphragm. To incorporate this feature, the inside flat surface of the rigid band needs to be spherical and convex. The diaphragm is a thin flexible membrane that is stretched across the spherical surface of the rigid band, and conforms to the spherical surface of the rigid band to form a seal. The crimp ring maintains the tension on the diaphragm. The diaphragm has a series of pierced holes around the diameter that is sealed by the spherical surface. As saline or gas is injected into the device, the increase in pressure between the septum and diaphragm causes the diaphragm to separate from the spherical surface, thereby creating a pathway for the gas to enter the balloon. Once the balloon has been inflated, and the injection process has stopped, the pressure differential within the balloon causes the diaphragm to seal against the spherical surface. The balloon can be deflated by either of the following two methods: (1) a needle can extend through both the septum and diaphragm and (2) a needle can extend through only the septum, and a plunger can then be extended to open the diaphragm. This second alternative could also be used to fill the balloon, while allowing the internal pressure of the balloon to be monitored during the inflation process.  
       [0020] The detachable balloon of the present invention can also be combined with an expanding stent to form a permanent, fixed embolic. For this alternative, the detachable balloon of the present invention described above is produced with three equally spaced axial bands that are over-molded onto the stent during the molding process, to produce an integral balloon/stent sub-assembly.  
       [0021] Further, the above concept for the balloon stent can be modified as follows to meet the requirements of the casein-based vaso-occluding stent of the present invention: (1) the expandable balloon is manufactured from a permeable material, such as PP, PTFE, PE, or another polymer with similar properties and (2) the balloon is attached to the internal periphery of the stent by three equally spaced flexible, folding connector bands.  
       [0022] When the balloon stent, modified to meet the requirements of the casein-based vaso-occulating stent of the present invention, is deployed at the target site, the modified balloon stent is expanded to grip the inner wall of the vessel by inflating the balloon briefly with either a saline solution or gas. The balloon is immediately deflated and returns to the original diameter and shape. Since the balloon is manufactured from a microporous barrier material, permeation of fluid or gas through the membrane does not occur during the brief period when the balloon is inflated to anchor the stent to the vessel wall. Also, the external surface of the balloon and device can be coated with heparin, or another thromboresistant drug, that will provide additional resistance to the flow of gas or fluid from the inside of the balloon into the blood stream. Expandable particles, such as PVA, gelatin foam, nBCA or a similar material, are injected into the balloon, filling the balloon without any expansion beyond the original shape. The heparin coating will dissolve shortly after the device is deployed enabling serum from the bloodstream to penetrate the barrier material and expand the particles over time. Similar to the casein-based vaso-occluding stent, the rate of occlusion is controlled by the porosity, both pore size and distribution, of the permeable balloon material.  
       [0023] The internal ligation device of the present invention is intended for use as part of a percutaneous catheteral procedure. The device includes the following six components: (1) non-absorbable monofilament or braided sutures, (2) sharpes to puncture the inner wall of the vessel, (3) slides to advance the sutures through the punctured holes, (4) a clamping mechanism to tie-off the sutures once the vessel is occluded, (5) cutting blades to sever the excess length of suture, and (6) a housing to retain the components and provide mechanical alignment for the ligation process. The sharp tips, cutting blades, and housing are manufactured from stainless steel or another material with similar properties. The clamping mechanism, the sharp sleeves, and the suture slides are manufactured from polypropylene or another polymer with similar properties.  
       [0024] The internal ligation device of the present invention would be placed at a target site using a percutaneous catheteral procedure as described above. Once in place, the sharps would be advanced from the catheter tip by the mechanical control of the interventional radiologist. The sharps are an integral part of the sharp sleeves and can be attached to the sharp sleeves by an insert molding operation or similar process. The sharp sleeves are molded into a curved shape, and they are flexed straight when assembled to and retained by the housing. When the sharp sleeves are extended from the housing, they return to their molded-in curvature. As they continue to extend from the housing, the sharps pierce the vessel wall adjacent to the housing end. The three sharps pierce the inner wall of the blood vessel at three evenly spaced points around the diameter.  
       [0025] The suture slides of the internal ligation device of the present invention are also molded from a flexible polymer. The thin cross-section of the suture slides allows them to easily conform to and follow the shape of the sharp sleeve. The ends of the sutures have preformed arms that have been folded back onto the length of each suture so that the folded end appears to be of slightly larger dimension as compared to the diameter of the remaining length of suture. The sutures are confined in the slides so that the suture arms remain folded back onto the length of the suture.  
       [0026] The suture slides of the internal ligation device of the present invention are advanced, through the sharp sleeves, and push the sutures through the holes in the vessel wall created by the sharps. Once the slides have pushed the sutures through the vessel wall, the arms of the sutures spring out to the preformed shape that extends significantly beyond the diameter of the hole in the vessel wall. The sharp sleeves and suture slides are retracted, and the sutures are pulled tightly to the clamping mechanism, thereby occluding the vessel. The excess length of suture is cut on the top surface of the clamping mechanism by the cutting blades.  
       [0027] The internal ligation device of the present invention could also be modified to allow the sutures to be cauterized rather than being clamped and cut. Another alternative would be to use a cauterizing operation to sever the sutures and bond the suture ends together, thereby eliminating the need for a clamping mechanism.  
       [0028] In summary, the following are the sequences of operations for the ligation of vessels with the internal ligation device of the present invention: (1) sharp sleeves and suture slides advance, (2) sharps pierce vessel wall, (3) suture slides continue to advance, (4) preformed sutures expand outside of the vessel wall, (5) suture slides retract to suture release surfaces, (6) the suture releases shed the sutures, (7) suture slides and sharp sleeves retract inside device, (8) sutures are pulled tight, (9) cutting blades advance, and (10) sutures are cut on the top surface of the clamps. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0029] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where:  
     [0030] FIGS.  1 ( a ) through  1 ( c ) show the cross-sections of the vaso-occluding stent of the present invention in the crimped state, deployed state, and expanded state, respectively.  
     [0031]FIG. 1( d ) is a perspective view of the device.  
     [0032] FIGS.  2 ( a ) and  2 ( b ) show how to make the casein sub-assembly and insert the casein sub-assembly into the stent.  
     [0033]FIG. 3 shows how to form the polypropylene barrier and hermetically seal the vaso-occluding stent with the polypropylene barrier.  
     [0034] FIGS.  4 ( a ) through  4 ( c ) show the detachable balloon device of the present invention located at the target site, the inflation of the balloon with a solution of saline and particles, and the completely expanded particles, respectively. The ratio of saline to particles is balanced to allow nearly complete absorption of the fluid.  
     [0035] FIGS.  4 ( d ) through  4 ( f ) show a cross-sectional view of the diaphragm assembly with the diaphragm closed, a front view of the diaphragm assembly, and a cross-sectional view of the diaphragm assembly with the diaphragm open, respectively.  
     [0036] FIGS.  4 ( g ) and  4 ( h ) show the deflation of the balloon with a needle and the deflation of the balloon using a needle and plunger, respectively.  
     [0037] FIGS.  5 ( a ) through  5 ( c ) show the balloon device of the present invention located at the target site, the inflation of the balloon with the solution of saline and particles, and the completely expanded particles respectively. Similar to the removable, detachable balloon, the ratio of saline to particles is balanced to allow near complete absorption of the fluid.  
     [0038] FIGS.  6 ( a ) through  6 ( d ) show the balloon device of the present invention located at the target site, the balloon inflated with saline to anchor the stent to the vessel wall, the deflated balloon injected with particles, and the inflated balloon after the particles have expanded from absorbing serum from the blood, respectively.  
     [0039] FIGS.  7 ( a ) and  7 ( b ) show the shape of the suture of the internal ligation device of the present invention when retained in the slide.  
     [0040]FIG. 7( c ) shows the unfolded suture arms.  
     [0041] FIGS.  7 ( d ) through  7 ( f ) show a cross-section of the device and identify the individual components.  
     [0042] FIGS.  7 ( g ) through  7 ( p ) show the sequential steps to the operation of the device.  
     [0043]FIG. 7( q ) shows the ligated vessel.  
     [0044]FIG. 7( r ) shows the internal ligation device and plungers. 
    
    
     DESCRIPTION OF THE INVENTION  
     [0045] The first embodiment of the present invention is shown in FIGS.  1 ( a )- 1 ( d ), the vaso-occluding stent  100  comprises an expandable stent  110  similar in size and function to an angioplasty stent, an expandable filler material, such as casein powder  120 , which has been bonded to a thin sheet of foil  140 . The casein/foil subassembly is contained within the stent  110 , and a barrier film  130  encapsulates the stent  110 , the formed casein  120 , and the foil  140 . Casein is an ideal material because the preformed shape does not delaminate from the foil or crack as it expands. The vaso-occluding stent  100  is placed into the blood stream using a percutaneous catheteral procedure. When deployed, the barrier film  130  will expand to follow the deployed diameter of the stent. As the casein  120  expands, the inner diameter of the vaso-occluding stent  100  will decrease until blood flow is completely occluded. Therefore, the barrier film  130  must be able to stretch significantly without rupture.  
     [0046] The stent  110  can be manufactured from Elgiloy, an alloy of cobalt, chromium, nickel and iron. Elgiloy is commonly used for stents and has superior mechanical properties, such as the modulus of elasticity or stiffness, as compared to  316  stainless steel. Elgiloy provides a high level of hoop strength to assure that internal pressure from the casein will not cause further expansion of the stent and damage to the vessel wall.  
     [0047] The casein  120  expands over time to slowly occlude blood flow through the vessel. The casein  120  is pressure formed onto a thin sheet of stainless steel foil  140 , and the casein/foil laminate  120 / 140  is spirally wound, as shown in FIG. 1( a ). When the vaso-occluding stent  100  expands from the crimped state (FIG. 1( a )) to the deployed state (FIG. 1( b )), the casein/foil laminate  120 / 140  will unwind uniformly. The foil  140  protects the formed casein from fracture as the vaso-occluding stent is deployed, and reduces the risk of fracture as the casein  120  expands. Without the foil  140 , the casein  120  would be driven through the stent  110  during deployment. Since expansion begins at the outer surface of the casein, the expansion rate is greater for the initial period and slows from that point until occlusion is complete. Various types of casein  120  can be used in this application among these are kappa-casein glycomacropeptide (GMP), also known as caseinomacropeptide (CMP). This type of casein is soluble and can be pressure formed and bonded to the stainless steel foil  140 . However, any inert, biocompatible, soluble material with similar expansion and mechanical properties can be used in place of the casein.  
     [0048] The barrier film  130  that encapsulates the stent  110 , foil  140  and casein powder  120  act as a barrier to retain any casein particles that could separate during deployment and controls the rate at which the casein will expand. This feature allows the occlusion rate to be optimized to support specific medical conditions and patient recovery and minimize mortality. The barrier film  130  is a micro-porous polypropylene (PP) film that is wrapped completely around the stent  110  and casein powder  120  and foil  140 . The barrier film  130  is heat sealed to provide hermetic encapsulation of the components that comprise the vaso-occluding stent  100 . Heparin can be applied to the barrier film  130  to improve thromboresistance by either photoderivatizing and coupling the heparin to the surface of the polymer, or coating an ionically bonded heparin anitcoagulant onto the polymer. The use of PP as the barrier allows the vaso-occluding stent to be sterilized through radiation exposure.  
     [0049] Placement of a vaso-occluding stent has been designed as a percutaneous catheteral procedure to reduce recovery time. Depending on the targeted site, the placement procedure begins with a small incision either near the groin to access to the femoral artery or near the neck to access the jugular. A catheter is inserted into the major vessel and guided to the targeted site by means of dye and duplex sonography to identify the location. A guide wire is then passed through the catheter, and the initial catheter tube is removed. The vaso-occluding stent is crimped onto a catheteral balloon and manipulated to the targeted vessel using the guide wire. For a larger diameter vessel, deployment can be completed using serial balloon angioplasty. For thromboresistance, heparin is administered to the site through the catheter following placement of the vaso-occluding stent. When used in conjunction with existing surgical procedures, the anti-thrombotic protocols typically used with those procedures will provide the same benefits to the vaso-occluding stent and the affected area of the vessel.  
     [0050] For use with the Bolton stent previously described, the outer diameter of the crimped stent is approximately 2.5 mm and the stent length is approximately 9.0 mm. When deployed, the stent diameter can expand from 3.5 to 6.0 mm in order to sufficiently expand and anchor to the inner wall of the vessel. In cases where the vessel diameter would require excessive elongation of the barrier, the vaso-occluding stent can be designed with additional barrier material on both ends. In other words, the stent would remain 9.0 mm long and the barrier would be 11.0 mm or longer. The diameter of the vaso-occluding stent can also be scaled to accommodate a larger diameter vessel. Shorter stents would be used to navigate a more tortuous route to the target site.  
     [0051] The expansion rate of the casein  120  is rapid initially and reduces over time until occlusion is complete. The pore size of the barrier film  130  is used to control the rate of expansion of the casein powder  120 . The maximum pore size should be no greater than 5 μm to avoid the ingress of bacteria. The pore size of the barrier film  130  can be adjusted below this value to create the desired rate of occlusion. The rate of occlusion also can be adjusted by changing the pore density of the barrier film. Although both PP and PTFE are available as micro-porous films, PP is preferred to PTFE for this application for the following reasons: (1) the ability to be heat sealed or bonded to itself, (2) PP is more hydrophilic than PTFE to allow serum to pass from the blood stream and be absorbed by the casein, (3) the ability to be sterilized with radiation, and (4) PP is considered to be a viable polymer for providing thromboresistance. If necessary, the hydrophilic capacity of the PP can be increased through the use of surfactants or radiation grafting.  
     [0052]FIG. 2( a ) and  2 ( b ) show the method of making the casein sub-assembly and inserting the casein sub-assembly into the stent, respectively. As shown in FIG. 2( a ), a roll of stainless steel  210  is unrolled through an embossing roll  220  to improve the bonding of casein thereto. Next, casein powder  230  is deposited from a bulk feeder  240  to the unwound stainless steel, and spread evenly on the sheet with a doctor blade  260 . Then, calendar rolls  270  pressure bond the casein powder to the stainless steel sheet. The casein/stainless steel sheet is cut to the proper width and rolled into individual coils.  
     [0053] As shown in FIG. 2 b , each individual coil  280  is unwound and fed to a spiral winder  250 . Before entering the spiral winder, the casein/stainless steel sheet is cut to the appropriate length and wound into a casein/foil subassembly by the spiral winder  250 . Then, the casein/foil  290  subassembly is inserted into the stent  295 . A spiral winder  250  used to produce constant force springs, battery electrodes or capacitors can be used.  
     [0054]FIG. 3 shows how to form the polypropylene barrier and hermetically seal the stent with the polypropylene barrier. As shown in FIG. 3, a section of the polypropylene barrier  310  is unrolled and cut to the appropriate length. Next, the cut section of the polypropylene film is folded  320  and wound  330 , as shown in FIG. 3. Then, a U-shaped seam  340  is ultrasonically welded into the barrier film and the casein foil subassembly is inserted therein. Then, the resulting assembly  350  is ultrasonically welded to form a top seam  360 . Finally, the top seam is folded  370  into the inside to form a hermetically sealed stent.  
     [0055] The vaso-occluding stent design of the present invention provides a minimally invasive method to occlude blood flow through a vessel at a predetermined rate. The vaso-occluding stent can be designed to occlude blood flow at any rate from a few hours to several weeks. Numerous benefits are gained from occluding blood flow at a slow rate. Among these is the potential for the local tissue to revascularize in an effort to support increased blood flow, and the potential to reduce shock and cramps from the loss of localized blood flow.  
     [0056] The device of the present invention can be used to occlude blood flow to benign tumors or similar indications and could also be used as an alternative to the Ameroid Constrictor in animals. Also, the design can be modified to provide partial occlusion.  
     [0057] The second embodiment of the present invention  400  is shown in FIGS.  4 - 6 . The detachable balloon  400  of the present invention is comprised of five components: (1) a preformed, expandable balloon  420  manufactured from latex or silicone or another elastomer with similar properties, (2) a septum  430  manufactured from an elastomer or another material with similar properties to provide an ingress to the inside of the expandable balloon  420  and a seal for the same, (3) a rigid band  440  manufactured from stainless steel, elgiloy, or a material with similar properties, to act as a sealing surface and to attach the septum  430  to the expandable balloon  420  and seal the device, (4) a crimp ring  450  to fix and seal the balloon  420  and septum  430  to the rigid band  440  at assembly, and (5) a solution of saline and expandable particles  470 , such as polyvinyl alcohol (PVA), gelatin foam, n-butyl-cyanoacrylate (nBCA) or a similar material, that are used to inflate the balloon  420  as shown in FIG. 4 a  and  4   b.    
     [0058] The present invention would be placed at a target site using a percutaneous catheteral procedure as described above. The present invention utilizes expandable particles as the media for inflating the expandable balloon  420 . Once the device  400  is in place, the solution  470  is injected via a syringe  495  through the septum  430  to completely expand the balloon  420  and allow the balloon  420  to anchor to the vessel wall  490  as shown in FIG. 4 b . The balloon  420  is sealed to eliminate the potential for deflation and migration as shown in FIG. 4 c . If a temporary blockage is required, the particles can be removed with a larger syringe  495 , thereby deflating the balloon. Depending on the starting size of the PVA particles, the full expansion can be determined to correctly size a larger syringe  495  for particle removal.  
     [0059] The detachable balloon  420  of the proposed design can also be filled with saline or gas as is currently typical in the medical device industry. For this alternative, the sealing integrity of the septum  430  can be greatly improved by the addition of a diaphragm  480  as shown in FIG. 4 d . To incorporate this feature, the inside flat surface of the rigid band  440  needs to be spherical and convex. The diaphragm  480  is a thin flexible membrane that is stretched across the spherical surface of the rigid band  440 , and conforms to the spherical surface of the rigid band  440  to form a seal as shown in FIG. 4 e . The crimp ring  450  maintains the tension on the diaphragm  480 . The diaphragm  480  has a series of pierced holes  485  around a diameter that is sealed by the spherical surface as shown in FIGS. 4 d  and  4   e . As saline or gas is injected into the device the increase in pressure between the septum  430  and diaphragm  480  causes the diaphragm  480  to separate from the spherical surface, thereby creating a pathway for the gas to enter the balloon  420  as shown in FIG. 4 f . Once the balloon  420  has been inflated, and the injection process has stopped, the pressure differential within the balloon  420  causes the diaphragm  480  to seal against the spherical surface. The balloon  420  can be deflated by either of two methods. A needle can extend through both the septum  430  and diaphragm  480  as shown in FIG. 4 g . Alternately, a needle can extend through only the septum  430 , and a plunger  496  can then be extended to open the diaphragm  480  as shown in FIG. 4 h . This second alternative could also be used to fill the balloon  420 , and to allow the internal pressure of the balloon  420  to be monitored during the inflation process.  
     [0060] The same concept can be combined with an expanding stent  410  to form a permanent, fixed embolic. For this alternative, the detachable balloon  420  described above is produced with three equally spaced axial bands  460  that are over-molded onto the stent  410  during the molding process, to produce an integral balloon  420 /stent  410  sub-assembly as shown in FIG. 5 a.    
     [0061] The concept for the balloon  420  stent  410  can be modified as follows to meet the requirements of the casein-based vaso-occluding stent  100 . (1) The expandable balloon  420  is manufactured from a permeable material, such as polypropylene (PP), polytetraflouroethylene (PTFE), polyethylene (PE), or another polymer with similar properties. (2) The balloon  420  is attached to the internal periphery of the stent  410  by three equally spaced flexible, folding connector bands  460  as shown in FIG. 5 a.    
     [0062] When the device is deployed at the target site, the stent  410  is expanded to grip the inner wall of the vessel by inflating the balloon  420  briefly with either a saline solution or gas as shown in FIG. 5 b . The balloon is immediately deflated and returns to the original diameter and shape. Since the balloon  420  is manufactured from a microporous barrier material, permeation of fluid or gas through the membrane does not occur during the brief period when the balloon  420  is inflated to anchor the stent  410  to the vessel wall  490 . Also, the external surface of the balloon  420  and device  400  can be coated with heparin, or another thromboresistant drug, that will provide additional resistance to the flow of gas or fluid from the inside of the balloon  420  into the blood stream. Expandable particles, such as polyvinyl alcohol (PVA), gelatin foam, n-butyl-cyanoacrylate (nBCA) or a similar material, are injected into the balloon  420 , filling the balloon  420  without any expansion beyond the original shape as shown in FIG. 5 c . The heparin coating will dissolve shortly after the device  400  is deployed enabling serum from the bloodstream to penetrate the barrier material and expand the particles over time as shown in FIG. 5 d . Similar to the casein-based vaso-occluding stent  100 , the rate of occlusion is controlled by the porosity, both pore size and distribution, of the permeable balloon  420  material.  
     [0063]FIGS. 6 a - 6   d  show the device located at the target site, the balloon  420  inflated with saline to anchor the stent  410  to the vessel wall  490 , the deflated balloon  420  injected with particles, and the inflated balloon  420  after the particles have expanded from absorbing serum from the blood, respectively. FIGS. 5 a - 5   c  show the same device similarly deployed and with the balloon  420  immediately and fully expanded to provide complete immediate occlusion.  
     [0064] The third embodiment is shown in FIGS. 7 a - 7   r . The internal ligation device  700  of the present invention is intended for use as part of a percutaneous catheteral procedure. The internal ligation device  700  is comprised of six components: (1) non-absorbable monofilament or braided sutures  760 , (2) sharps  740  to puncture the inner wall of the vessel  490 , (3) slides  750  to advance the sutures through the punctured holes, (4) a clamping mechanism  780  to tie-off the sutures  760  once the vessel is occluded, (5) cutting blades  790  to sever the excess length of suture  760 , and (6) a housing  710  to retain the components and provide mechanical alignment for the ligation process as shown in FIG. 7 d . The sharps  740 , cutting blades  790 , and housing  710  are manufactured from stainless or another material with similar properties. The clamping mechanism  780 , the sharp sleeves  745 , and the suture slides  750  are manufactured from polypropylene or another polymer with similar properties.  
     [0065] The internal ligation device  700  housing  710  is placed at the target site using a percutaneous catheteral procedure as is known in the art. A user such as an interventional radiologist mechanically controls the internal ligation device by the use of plungers  791 ,  792 ,  793 ,  794 ,  795  as are known in the art and as are shown in FIG. 7 r . Once in place, as shown in FIG. 7 g , the sharps  720  are advanced from the catheter tip, as shown in FIG. 7 h , by the mechanical control of an interventional radiologist. The sharps  740  are an integral part of the sharp sleeves  745  and are attached to the sharp sleeves  745  through an insert molding operation or similar process. The sharp sleeves  745  are molded into a curved shape, and they are flexed straight when assembled to and retained by the housing  710  as shown in FIG. 7 g . When the sharp sleeves  745  are extended from the housing  710  the sharp sleeves  745  return to their molded-in curvature as shown in FIG. 7 h . As the sharp sleeves  745  continue to extend from the housing  710 , the sharps  740  pierce the vessel wall  490  adjacent to the housing  710  at evenly spaced points around the vessel perimeter FIG. 7 h . The suture slides  750  are also molded from a flexible polymer and their thin cross-section allows them to easily conform to and follow the shape of the sharp sleeve  740 . The ends of the sutures  760  exposed outside of the suture slides  750  have preformed arms  770  which are folded back onto the suture  760  end, and when folded back appear to be of slightly larger dimension as compared to the diameter of the remaining length of the suture  760 . The suture arms  770  remain folded back onto the length of the suture  760  when confined in the suture slides  750  as shown in FIG. 7 a  and  7   b . The suture slides  750  are advanced, through the sharp sleeves  745 , and push the sutures  760  through the holes in the vessel wall  490  created by the sharps  740  as shown in FIG. 7 i . Once the suture slides  750  have pushed the sutures  760  through the vessel wall, the arms  770  of the sutures  760  spring out, as shown in FIG. 7 c , to the preformed shape that extends significantly beyond the diameter of the hole in the vessel wall  490  as shown in FIG. 7 j . The sharp sleeves  745  and suture slides  750  are retracted as shown in FIGS. 7 k - 7   m , and the sutures  760  are pulled tightly to the clamping mechanism  780 , thereby occluding the vessel as shown in FIGS. 7 p  and  7   q . The excess length of suture  760  is cut on the top surface of the clamping mechanism  780  by the cutting blades  790  as shown in FIG. 7 n  and  7   o . The device  700  could also be modified to allow the sutures  760  to be cauterized rather than being clamped and cut. Another alternative would be to use a cauterizing operation to sever the sutures  760  and bond the suture  760  ends together, thereby eliminating the need for a clamping mechanism  780 .