Patent Publication Number: US-2005125022-A1

Title: Blood vessel occlusion device

Description:
This is a continuation-in-part of U.S. Ser. No. 10/086,753 filed on Mar. 1, 2002, entitled “Blood Vessel Occlusion Device” (Attorney Docket No. EU159411896US), which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to medical devices that are implanted in the human body. In particular, the present invention relates to medical devices that can be used to occlude blood vessels on a temporary or permanent basis.  
      2. State of the Art  
      Various implantable medical devices have been developed for treating ailments of the human body. One such implantable medical device is an occlusion device used to occlude blood vessels i.e. to prevent the flow of blood through these vessels. These occlusion devices may be used to occlude blood vessels either temporarily or permanently. In certain cases, for example, during a surgery, these devices may be used to stem the flow of blood while the surgery is performed. In other cases, such as in treatment of certain cardiovascular diseases, permanent occlusion devices may be used.  
      There are numerous situations where certain blood vessels such as arteries and veins may have to be occluded. Surgical treatment of an aneurysm is one such situation where occlusion devices are required. An aneurysm is a balloon-like swelling of a blood vessel such as an artery. This swelling may be caused due to diseases such as arteriosclerosis or cystic medial necrosis, or due to infections such as syphilitic or mycotic infections, or even due to trauma. Typically, the aneurysm results in a weakening of the wall of the artery or other blood vessel in which it occurs. The region of the artery (or the blood vessel) that has been affected by the aneurysm may tear or rupture over time because of sustained blood pressure. If the artery tears or ruptures, and consequently bleeding occurs, then there may be severe consequences for the patient. For instance, if an aneurysm affected artery in the brain bursts due to a weakened wall, then cranial hemorrhaging and subsequent death may occur. Hence, aneurysms occurring in certain regions of the body may lead to life-threatening conditions and therefore need to be detected early and treated suitably.  
      Although an aneurysm may occur in any location of the human body, it is more likely to occur in the abdominal aorta. This type of aneurysm is referred to as an Abdominal Aortic Aneurysm (AAA). An AAA usually results in a large swelling in the affected region of the aorta. In cases where the aneurysm affected region of the aorta exceeds 6 cm in diameter, surgery may be necessary to treat the aneurysm as the weakened walls of the aorta may not be able to withstand the pressure of blood flowing through the aorta, and in extreme cases, the aorta may rupture in the affected region leading to internal hemorrhaging.  
      Surgical treatment of AAA typically provides an alternate path for the flow of blood so as to bypass the aneurysm affected region of the aorta. Typically, the bypass is a graft that replaces the affected portion of the aorta.  
      In this surgery, a surgeon makes an incision in the abdominal wall of the patient and gains access to the aneurysm affected region of the aorta. Then, the surgeon clamps the aorta above and below the aneurysm affected region in order to block the flow of blood through the aorta. In the next step, the surgeon opens the aneurysm affected region of the aorta and provides an alternate path for the flow of blood with the bypass graft. As a result, the affected region is bypassed.  
      Once the affected portion of the aorta has been opened, the blood vessels that originate from this cut region of aorta (i.e., the collateral circulation system) are exposed and begin to bleed profusely. Hence, in such cases it is necessary to seal these blood vessels to prevent excessive loss of blood. In such cases, occluding means are often employed during the surgery to prevent excessive bleeding from such blood vessels. In a collateral circulation system, two or more arteries are interconnected by multiple smaller arteries and/or capillaries. Such an interconnected network of arteries leads to sufficient redundancy in the network. Therefore, if one of these arteries is blocked or damaged or otherwise rendered ineffective, blood is still supplied to regions of the body. However, this redundancy in the circulation system also leads to problems when one of these arteries is cut or left open to a larger artery such as the aorta. For instance, the exposed branch arteries may start to bleed since the exposed artery would draw blood from the collateral circulation system. Consequently, arteries that are exposed during this surgical procedure need to be quickly and effectively sealed. In this surgery, opening of the aneurysm affected region of the aorta often exposes  4  to  6  or more collateral arteries that originate in this region. The surgeon must occlude these arteries.  
      Three techniques are usually employed to occlude blood vessels. These include sealing of a blood vessel using a finger, sealing of the blood vessel using a clamp or a clip, and suturing of the blood vessel (which is most commonly used in the AAA surgery).  
      The first technique is the simplest, as a surgeon or other person assisting in the surgery seals the cut blood vessel using a finger. This technique is regularly used since the finger may be readily applied to seal the cut blood vessel. However, this method is often not suitable due to certain drawbacks. First, the space available in the site of the surgery may be reduced considerably. Second, the hand of the person may not allow the blood vessel to be clearly seen and operated upon, and hence this technique may hinder access to the site of the surgery. Third, where numerous blood vessels must be simultaneously sealed, it is difficult to accomplish this using fingers. Fourth, this technique is not a permanent sealing arrangement. Because of these drawbacks, this technique is rarely used to occlude the affected blood vessels (for the entire duration of the surgery). Instead, this technique is sometimes used while another occluding means is applied to the blood vessel.  
      In an alternative technique, a clamp or a clip may be used to occlude a blood vessel. In this technique, the clamp or clip is used to constrict the blood vessel so as to minimize blood flow through the narrow opening in the blood vessel. The surgical clamps and “ligating” clips come in a variety of shapes and sizes. In a typical design, a surgical clamp is connected to an elongated arm and is controlled with a handle. The elongated arm allows the surgeon to apply and remove the clamp easily during the surgery. Two such surgical clamps have been disclosed in U.S. Pat. Nos. 5,133,724 and 5,447,515. However, such designs are not always suitable since the long arm or handle may hinder the surgeon&#39;s access to the affected blood vessel.  
      Alternative designs of clamps also exist where the handle or other such clamp applier may be readily removed from the site of the surgery. U.S. Pat. No. 5,282,812 discloses one such clamp. However, such a surgical clamp has the drawback that it is difficult to quickly loosen or remove the clamp. In this method, the difficulty arises since the surgeon must apply the appropriate amount of force by hand for loosening and removing the clamp. Another drawback of these occlusion devices is that these may not be effective in completely sealing certain blood vessels. For instance, a blood vessel such as an artery usually has a very thick wall. Therefore, it may not be possible to completely seal such an artery using a clamp or a clip. Furthermore, the clamps may slip and slide out of position if a sufficiently large clamping force is not applied. However, this large clamping force may permanently damage the wall of the artery. Finally, the use of ligating clips and clamps is a temporary arrangement because it is not desirable to leave a metallic clamp inside a human body for a long duration. Thus, clamps and clips may not always be suitable for occluding blood vessels.  
      A third technique to occlude blood vessels is to suture these vessels. This technique allows the blood vessel to be completely sealed. However, suturing is usually a time-consuming procedure as compared to other methods mentioned above. Consequently, suturing may not be suitable for all surgical procedures. For instance, consider the surgical procedure used to treat an aneurysm in the lumbar region of the body. In this surgical procedure, a large number of blood vessels must be occluded in order to treat the aneurysm. Hence, if the vessels are cut and sutured, as is done currently, then there may be considerable loss of blood before all blood vessels have been occluded. Moreover, there may be difficulties in the suturing process itself if there are calcium deposits in the area of the aneurysm. Calcium deposits are likely to occur in this region since aneurysms usually begin as micro-tears in the wall of the blood vessel, and calcium and other blood coagulating material are likely to deposit at the site of these tears. Furthermore, these calcium deposits may also weaken sutures that have been applied thereby decreasing the effectiveness of this technique.  
      Consequently, there is a need to quickly and effectively occlude blood vessels during surgical procedures. It should be noted that the need for occluding blood vessels occurs not only in surgery for treating aneurysms but also in other surgeries. Therefore, it would be desirable to have sealing devices capable of permanently and/or temporarily occluding a variety of blood vessels in different regions of the body.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the present invention to provide several means for permanently and temporarily occluding blood vessels such as an artery.  
      It is another object of the invention to provide means for occluding a blood vessel which has calcium or arteriosclerosis plaque deposits therein.  
      It is a further object of the invention to provide blood vessel occluding plugs and tools for inserting those plugs into a blood vessel.  
      In accord with the objects of the invention which will be discussed in more detail hereinafter, various blood vessel occlusion devices (plugs) are disclosed. In all cases, the plugs, or at least portions thereof, are made of silicone or other biocompatible material and include a pilot hole which permits an insertion device to be used to insert the plug into the blood vessel. The plugs of the present invention allow blood vessels to be rapidly occluded. Certain embodiments of the plug may be used to permanently seal the blood vessel, while other embodiments of the plug are designed to temporarily occlude a blood vessel. The plugs of the present invention are designed to be effective even in cases of deposits, such as calcium and/or plaque deposits, in the artery.  
      Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a first embodiment of a permanent occlusion device inserted in a blood vessel in accordance with the present invention.  
       FIG. 2  is a bottom perspective view of the occlusion device of  FIG. 1 .  
       FIG. 3  is a perspective view of an insertion device in accordance with the present invention.  
       FIG. 4  is an exploded view of the insertion device of  FIG. 3 .  
       FIGS. 5-9  shows a second embodiment of a temporary occlusion device that includes a large diameter disc-like section in accordance with the present invention.  
       FIGS. 10 and 11  are cross-sectional views of third and fourth embodiments of the present invention where inserts formed from hard plastic are provided.  
       FIGS. 12A and 12B  are perspective views of a fifth embodiment of the present invention; where a slidable insert formed from hard plastic is seen in first and second positions.  
       FIGS. 13A and 13B  are perspective views of a sixth embodiment of the present invention; where a disc-like flap is section formed from an elastomeric biocompatible material.  
       FIG. 13C  is a cross-sectional view through the central axis of the device of  FIG. 13A . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       FIG. 1  illustrates an artery  104  that has been occluded using a plug  102  in accordance with the present invention. Artery  104  has a lumen  106  through which the blood flows and plug  102  has been inserted axially into lumen  106  to occlude artery  104 . Preferably, the external surface  107  of plug  102  is symmetric about an axis  108  as shown. Furthermore, the external surface  107  preferably tapers from a base  109  disposed at one end to a rounded top portion  110  as shown. To facilitate insertion of the plug  102  into artery  104 , the cross-sectional diameter of the rounded end  110  is smaller than the diameter of lumen  106 . Moreover, to ensure that the plug  102  remains at its desired position in the artery  104 , the cross-sectional diameter of the base  109  is larger (typically on the order of 10 to 35 percent larger and preferably between 25 to 30 percent larger) than the diameter of lumen  106 . The plug  102  also preferably includes spring-biased prongs  208  that extend below the base  109  and radially outward with respect to axis  108  as shown.  
      Artery  104  has a thick elastic wall surrounding lumen  106 . This thick wall has been provided so as to withstand flow of blood at high pressure through artery  104 . The elastic nature of artery  104  allows plug  102  to be tightly grasped by artery  104 . More specifically, when the plug  102  is inserted into its desired position in artery  104 , the larger diameter base  109  and possibly the spring-biased prongs  208  (which extend radially into the elastic wall of the artery  104 ) cause the elastic wall of the artery  104  to be deformed such that the plug  102  is tightly grasped by the wall of the artery  104  as shown. Therefore, the elastic nature of the walls enables the plug  102  to be effective in occluding artery  104 . Furthermore, the elastic walls of artery  104  also permit a small range of plugs  102  of varying diameter to be used for different sizes of arteries  104 . Thus, plug  102  of a certain size may be used for occluding arteries of different sizes. Typically, plug  102  ranges from 1 mm to 4 mm in maximum cross-sectional diameter.  
      As shown in  FIG. 2 , the exterior surface  107  of plug  102  is formed by a layer  202  of biocompatible material. Preferably, silicone is used to form layer  202 . Silicone is useful since it is non-toxic, chemically inert, substantially insoluble in blood and substantially non-immunogenic. In addition to silicone, newer elastomeric biocompatible materials may also be used to manufacture the layer  202 . Ongoing research and development in biocompatible materials have created materials with a longer life, better strength and lower cost-all of which are desirable qualities of the material of the exterior surface layer  202 . Typical examples of such materials include polyurethanes and polyisobutylene-based polymers.  
      Plug  102  is preferably provided with a frame structure  204  that supports the exterior surface layer  202  such that surface layer  202  withstands the forces acting upon it when the plug  102  is inserted into the artery  104 . More specifically, upon inserting the plug  102  into artery  104 , the elastic walls of the artery exert a compressive force on the exterior surface layer  202 . Furthermore, pressure of blood in the artery  104  exerts an axial force on the exterior surface layer  202 . The frame structure  204  mechanically supports the exterior surface layer  107  to counteract these forces. Preferably, the frame structure is corrugated and includes projections  206  that extend radially inward toward the central axis  108  as shown. These features provide for increased strength of the frame structure  204 . In the exemplary plug shown, the frame structure  204  includes four projections that are spaced 90 degrees apart. The radial width of each projection tapers from a point near the top of the projection to the bottom of the projection as shown. The top of the frame structure  204  mechanically supports a prong structure which includes a plurality of spring-biased (preferably metal) prongs  208  and an integral base  209  which is joined to the prongs by joints  211 . In the exemplary plug shown, the four spring-biased prongs  208  are spaced 90 degrees apart. In addition, the base  209  of the prong structure and the top of the frame structure  204  includes pilot holes  210   a ,  210   b . These pilot holes are sized to receive an insertion device  300  and thereby enable plug  102  to be mounted on an insertion device  300  as described below with respect to  FIG. 3 . Preferably, the frame structure  204 , including projections  206  and prongs  208 , are made of hard plastic and/or metal (such as titanium) or some other material of sufficient rigidity and strength.  
      In an alternative embodiment (not shown) of plug  102  of  FIGS. 1 and 2 , the plug  102  may be constructed without any prongs  208 . In this embodiment, plug  102  may be manufactured using materials of sufficient structural rigidity and strength. Furthermore, the prongs  208  may be avoided by suitably increasing the thickness of the frame structure  204 .  
      In a typical surgery, the plug  102  is inserted into artery  104  by substantially aligning the axis  108  of the plug  102  with the longitudinal axis of the artery  104 , and by applying a force along the axis  108 . The surgeon may apply this force either by hand (if feasible) and/or by using a deployment mechanism such as insertion device  300  shown in  FIG. 3 . This insertion device  300  has a casing  302  and a lever  306 . The surgeon uses the lever  306  to operate the insertion device  300 . Lever  306  enables a needle  308 , housed in a tubular needle guard  310 , to be retracted inwards. To insert the plug, the surgeon mounts a plug  102  on the needle  308  of the insertion device (if the plug is not already pre-mounted). This is done by inserting the needle  308  into the pilot holes  210  of the plug  102  such that the distal end  311  of the needle guard butts up against the base  209  of the prong structure. Next, the surgeon aligns the axis  108  of the plug  102  with the longitudinal axis of the artery  104 , and applies an axial force to the insertion device  300 , thereby inserting the needle  308  and the plug  102  mounted thereon to a desired position in artery  104 . As the plug is pushed in the lumen of the artery, the downward angle of the ends of the prongs  208  enables the prongs  208  and plug body ( 107 ,  204 ,  206 ) to slide along the walls of the artery. In addition, the constricting force of the artery compresses the plug body ( 107 ,  204 ,  206 ), which in turn causes the ends of the prongs  208  to be retracted inward with respect to the central axis. In this manner, any damage caused by the prongs  208  to the inner walls of the artery is limited. When force is no longer applied by the surgeon, the prongs  208  spring outwardly and dig into the walls of the artery. The prongs  208  together with small diameter of plug  102  with respect to the diameter of the lumen of the artery  104  enables the elastic walls of the artery  104  to tightly grip and secure the plug  102  as described above. The surgeon then presses button  306  to retract the needle  308  inward such that it is housed in the needle guard  310  and becomes disengaged from the pilot holes  210 , thereby releasing the plug  102  from the insertion device  300 .  
       FIG. 4  shows an exploded view of insertion device  300 . This device is essentially a spring activated device. A spring  400  and a needle guide  402  have been shown encased in casing  302 . When the lever  306  is activated, it propels needle guide  402  toward the back end  312 . In turn, this needle guide propels the needle  308  inwards such that it retracts into the distal end  311  of needle guard  310 . Hence, the needle  308  is released from plug  102 . When the lever  306  is not activated, the spring  400  propels needle guide  402  such that it moves away from the back end  312 . In turn, the needle guide propels needle  308  outward such that it is extends from the distal end  311  of guard  310 . It will be apparent to one skilled in the art that alternative ways to propel the needle may be employed by the insertion device  300 . A lock may be added to deactivate the lever  306  and needle guide  402  such that once the lever  306  has been activated to deploy the plug, the needle  308  remains inside and shrouded by the guard  310  to avoid accidental trauma to the patient, surgeon or nurse.  
      The plug device  102  of  FIGS. 1 and 2  is designed to provide a permanent occlusion of an artery  104 . In other words, it is not meant to be removed. Such a design is useful in many different surgical procedures, for example those requiring that one or more of the intercostal arteries (or lumbar arteries) be permanently occluded. However, in certain circumstances, it may be desirable to provide a mechanism to remove the “permanent” occlusion device. This may be accomplished by pushing on the base  209  of the prong structure  208  (e.g., by inserting a rigid needle/guide structure into pilot holes  210  and pushing with axial force). This will cause the spring-biased prongs  208  to retract radially inward. A relatively rigid sleeve may then be slipped over the retracted prongs so that the prongs  208  do not impale the arterial walls and so that the plug  102  may be pulled from the lumen  106  of the artery  104 .  
       FIGS. 5-9  illustrate a second embodiment of blood vessel occlusion device  500  in accordance with the present invention. Device  500  is a plug intended for temporary occlusion of a vessel such as an artery. Preferably, the external surface  507  of plug  102  is symmetric about an axis  508  as shown. Furthermore, the external surface  507  preferably tapers from a base  509  to a rounded top portion  510  as shown. As best shown in  FIGS. 8 and 9 , a disc-shaped section  511  extends from the base  509 , and a bottom section  512  extends from the underside of the disc-shaped section  511  as shown. The bottom section  512  includes holes  514 A,  514 B that pass through corresponding flat walls structures  515 A,  515 B as shown. A thread  513 , which may be realized by a braided silk suture, a monofilament suture, other suture material, natural or artificial fibers, single filament or multifilament threads, or other suitable material that provides suitable tensile strength (hereinafter referred to as a “thread”), is provided. The thread  513  extends through the holes  514 A,  514 B (and may be knotted as shown). The thread  513  enables the surgeon to pull on the plug device  500  and thereby remove it from artery  104 . Preferably, a needle is threaded with the thread  513 , and the needle/thread  513  is used to puncture the flat walls structures  51  SA,  51  SB to form the holes  514 A,  514 B therein and contemporaneously pass the thread  513  through these holes. In addition, the bottom section  512  preferably includes a pilot hole  516 . This pilot hole  516  enables plug device  500  to be mounted on an insertion device  300 , as described above with respect to  FIGS. 1-4 .  
      To facilitate insertion of the plug device  500  into artery  104 , the cross-sectional diameter of the rounded end  510  is smaller than the diameter of lumen  106 . Moreover, to ensure that the plug device  500  remains at its desired position in the artery  104 , the cross-sectional diameter of the disc-shaped section  511  (labeled D in  FIG. 5 ) is larger (typically on the order of 10 to 35 percent larger and preferably between 25 to 30 percent larger) than the diameter of lumen  106 . Artery  104  has a thick elastic wall surrounding lumen  106 . This thick wall has been provided so as to withstand flow of blood at high pressure through artery  104 . The elastic nature of artery  104  allows plug  500  to be tightly grasped by artery  104 . More specifically, when the plug device  500  is inserted into its desired position in artery  104 , the larger diameter disc-shaped portion  511 , which extends radially into the elastic wall of the artery  104 , cause the elastic wall of the artery  104  to be deformed such that the plug device  500  is tightly grasped by the wall of the artery  104  as shown. Therefore, the elastic nature of the walls enables the plug device  500  to be effective in occluding artery  104 . Furthermore, the elastic walls of artery  104  also permit a small range of plugs  500  of varying diameter to be used for different sizes of arteries  104 . Thus, plug device  500  of a certain size may be used for occluding arteries of different sizes. Typically, plug device  500  ranges from 1 mm to 3 cm (and preferably in the range between 2 mm and 2 cm) in maximum cross-sectional diameter.  
      In a typical surgery, the plug device  500  is inserted into artery  104  by substantially aligning the axis  508  of the plug device  500  with the longitudinal axis of the artery  104 , and by applying a force along the axis  508 . The surgeon may apply this force either by hand (if feasible) and/or by using an insertion device such as insertion device  300  shown in  FIG. 3 . This insertion device  300  has a casing  302  and a lever  306 . The surgeon uses the lever  306  to operate the insertion device  300 . Lever  306  enables a needle  308 , housed in a tubular needle guard  310 , to be retracted inwards. To insert the plug device  500 , the surgeon mounts plug device  500  on the needle  308  of the insertion device (if the plug is not already pre-mounted). This is done by inserting the needle  308  into the pilot hole  516  of plug device  500  such that the distal end  311  of the needle guard butts up against the bottom section  512 . Next, the surgeon aligns the axis  508  of the plug device  500  with the longitudinal axis of the artery  104 , and applies an axial force to the insertion device  300  thereby inserting the needle  308  and the plug device  500  mounted thereon to a desired position in artery  104 . This force inserts plug device  500  into artery  104 ; the artery has a smaller diameter than that of plug device  500 ; further, the elastic walls of artery  104  tightly grip and secure plug device  500  as described above. The surgeon then presses button  306  to retract the needle  308  inward such that it is housed in the needle guard  310  and becomes disengaged from the pilot hole  526 , thereby releasing the plug device  500  from the insertion device  300 . In order to remove the plug device  500  from its occluding position in artery  104 , the surgeon grasps onto and pulls thread  513 , which is attached to the bottom section  512 , such that the plug device  500  is pulled from the lumen  106  of the artery  104 .  
      The plug device  500  is formed preferably from an elastomeric biocompatible material such as silicone. As described above, silicone is useful since it is non-toxic, chemically inert, substantially insoluble in blood and substantially non-immunogenic. In addition to silicone, newer elastomeric biocompatible materials may also be used such as polyurethanes and polyisobutylene-based polymers. Moreover, plug  500  is preferably formed via molding techniques such that the structural elements described above are formed from a unitary piece of material.  
      Preferably, the outer portion of the disc-like section  511  of the plug device  500  is capable of deflecting downward (backward toward the insertion device) when the plug device  500  is inserted into the artery  104  as shown in  FIG. 6 , and is capable of deflecting upward (forward away from the insertion device) when the plug device is removed from the artery  104  as shown in  FIG. 7 . Such deflection facilitates the insertion and removal of the plug device  500  as described above. Such deflection is preferably enhanced by forming the plug with an annular void (e.g., cutaway section)  517  in the bottom part of the disc-like section  511  adjacent the bottom section  512  as best shown in  FIGS. 8 and 9 . This annular void  517  provides a hinge-like effect which enables the outer portion of the disc-like section  511  to deflect downward (backward) and upward (forward) when the plug device  500  is respectively inserted into and removed from the artery  104  as shown in  FIGS. 6 and 7 . Preferably, the upward (forward) deflection of the disc-like section  511  has a greater range than its downward (backward) deflection. The limited range of downward (backward) deflection afforded by void  517  enables the plug  500  to resist blood pressure and be readily removed at the appropriate time during treatment.  
      As described above, the removal thread  513  passes through holes in the bottom section  512  of the plug device  500 . In alternate embodiments, the thread  513  may pass through holes that are formed in other portions of the plug device  500 . For example, the thread  513  may pass through the annular void  517  and further through holes formed in the disc-like section  513  such that it wraps around the top (forward) part of the disc-like section  513 .  
       FIGS. 10 and 11  illustrate third and fourth embodiments of blood vessel occluding devices which are similar in various ways to the second embodiment described above with respect to  FIGS. 5 through 9 . In the embodiment of  FIG. 10 , plug  500 ′ is provided with an insert  521  is disposed along the central axis  508  of the plug device  500 ′. The insert  521 , which is preferably formed from a hard plastic such as nylon or Liquid Crystal Polymer (LCP), includes a barbed section  522  that mechanically affixes the insert  521  to the plug body (sections  511 ,  509 ,  510 ). An eyelet  523  in the insert  521  is provided such that a thread  513  can extend therethrough. The thread  513 , enables the surgeon to pull on the plug device  500 ′ and thereby remove it from artery  104 . The insert  521  also includes a pilot hole  524  that enables plug device  500 ′ to be mounted on an insertion device  300 , as described above.  
      In the embodiment of  FIG. 11 , plug  500 ″ is provided with an insert  525  which is disposed along the central axis  508  of the plug device  500 ″. The insert  525 , which is preferably formed from a hard plastic such as nylon, includes a middle section  526  disposed between a rounded top section  527  and a bottom section  528 . The plug body (sections  509 ,  511 ) is slid over the rounded top section  527  such that it is mechanically supported by the middle section  536  and positioned between the rounded top section  527  and the bottom section  528 . Alternatively, the plug body is molded around the middle section  536  of the insert. An eyelet  529  in the bottom (rear) section of the insert is provided such that the thread  513  can extend therethrough. The thread  513  enables the surgeon to pull on the plug device  500 ″ and thereby remove it from artery  104 . The bottom section  528  of the insert  525  also includes a pilot hole  530  that enables plug device  500 ″ to be mounted on an insertion device  300 , as described above with respect to  FIGS. 3 and 4 , or other needle-based insertion device.  
      The embodiments of  FIGS. 10 and 11  advantageously utilize hard plastic to attachment the thread  513  to the plug device, thereby minimizing the risk of tearing the plug body when pulling on the thread  513  during removal of the plug device.  
       FIGS. 12A and 12B  illustrate another alternative embodiment of a blood vessel occluding device  600  in accordance with the present invention. The plug device  600  includes a sliding insert  601  disposed along the central axis  608  of the plug device  600 . The sliding insert  601 , which is preferably formed from a hard plastic such as nylon, includes a top rounded portion  602 , a coupling shaft  603 , a bulbous section  604  and a bottom section  605 . An umbrella-shaped plug body  606 , preferably formed from an elastomeric biocompatible material such as silicone, surrounds the coupling shaft  603  and has a tapered structure that accepts the bulbous section  604  when the insert  601  is moved upward along the central axis  608  with respect to the plug body  606 . In this manner, by moving the insert  601  upward along the central axis  608  with respect to the plug body  606 , the bulbous section supports the plug body  606  in an expanded state whereby the diameter of the plug body  606  is increased as shown in  FIG. 12A . An eyelet  607  in the sliding insert  601  is provided such that a thread  613  can extend therethrough. The thread  613  enables the surgeon to pull on the plug device  600  and thereby remove it from the lumen  106  of artery  104 . When the surgeon pulls on the thread  613 , the insert  601  moves downward along the central axis  608  with respect to the plug body  606 , and the bulbous section  604  no longer supports the plug body  606 . As a result, the plug body  606  relaxes and may be placed in a relaxed/natural state (by the artery  104 ) whereby the diameter of the plug body  606  is decreased as shown in  FIG. 12A . This relaxed state and decreased plug diameter facilitates easy removal of the plug device  600  from the artery. The sliding insert  601  also includes a pilot hole  624  that enables plug device  600  to be mounted on an insertion device  300 , as described above.  
      To facilitate insertion of the plug device  600  into artery  104 , the cross-sectional diameter of the rounded end  602  is smaller than the diameter of lumen  106 . Moreover, to ensure that the plug device  600  remains at its desired position in the artery  104 , the maximum cross-sectional diameter of the plug body  606  in its expanded state is larger (typically on the order of 10 to 35 percent larger and preferably between 25 to 30 percent larger) than the diameter of lumen  106 . Artery  104  has a thick elastic wall surrounding lumen  106 . This thick wall has been provided so as to withstand flow of blood at high pressure through artery  104 . The elastic nature of artery  104  allows plug  500  to be tightly grasped by artery  104  when the plug  600  is in its expanded state. More specifically, when the plug device  600  is inserted into its desired position in artery  104 , the larger diameter plug body  606  (in its expanded state), which extends radially into the elastic wall of the artery  104 , causes the elastic wall of the artery  104  to be deformed such that the plug device  600  is tightly grasped by the wall of the artery  104  as shown in  FIG. 12A . Therefore, the elastic nature of the walls enables the plug device  600  to be effective in occluding artery  104 . Furthermore, the elastic walls of artery  104  also permit a small range of plugs  600  of varying diameter to be used for different sizes of arteries  104 . Thus, plug device  600  of a certain size may be used for occluding arteries of different sizes. Typically, plug device  600  ranges from 1 mm to 3 cm (and preferably in the range between 2 mm and 2 cm) in maximum cross-sectional diameter.  
       FIGS. 13A-13C  illustrate another exemplary blood vessel occlusion device  700  in accordance with the present invention. Preferably the external surface  707  tapers from a base  709  to a rounded top portion  710  as shown. As best shown in the cross-section of  FIG. 13C , a large diameter disc-shaped flap  711  extends from the base  709 , and a bottom section  712  extends from the underside of the disc-shaped flap  711  as shown. The bottom section  712  includes holes  714 A,  714 B that pass through corresponding flat walls structures  715 A,  715 B as shown. A thread  713  extends through the holes (and may be knotted). The thread  713  enables the surgeon to pull on the plug device  700  and thereby remove it from artery  104 . In addition, the bottom section  712  preferably includes a pilot hole  716  as best shown in 
           FIG. 13C . This pilot hole  716  enables plug device  700  to be mounted on an insertion device  300 , as described above.        
      To facilitate insertion of the plug device  700  into artery  104 , the cross-sectional diameter of the rounded end  710  is smaller than the diameter of lumen  106 . Moreover, to ensure that the plug device  700  remains at its desired position in the artery  104 , the cross-sectional diameter of the disc-shaped flap  711  is larger (typically on the order of 10 to 35 percent larger and preferably between 25 to 30 percent larger) than the diameter of lumen  106  when inserted into the lumen of the artery. This inserted state is shown in  FIG. 13A . Artery  104  has a thick elastic wall surrounding lumen  106 . This thick wall has been provided so as to withstand flow of blood at high pressure through artery  104 . The elastic nature of artery  104  allows plug  700  to be tightly grasped by artery  104 . More specifically, when the plug device  700  is inserted into its desired position in artery  104 , the larger diameter disc-shaped flap  711 , which extends radially into the elastic wall of the artery  104 , cause the elastic wall of the artery  104  to be deformed such that the plug device  700  is tightly grasped by the wall of the artery  104 . Therefore, the elastic nature of the walls enables the plug device  700  to be effective in occluding artery  104 . Furthermore, the elastic walls of artery  104  also permit a small range of plugs  700  of varying diameter to be used for different sizes of arteries  104 . Thus, plug device  700  of a certain size may be used for occluding arteries of different sizes. Typically, plug device  700  ranges from 1 mm to 3 cm (and preferably in the range between 2 mm and 2 cm) in maximum cross-sectional diameter. In order to remove the plug device  700  from its occluding position in artery  104 , the surgeon grasps onto and pulls thread  713 , which is attached to the bottom section  712 , such that the disc-like flap  711  collapses as shown in  FIG. 13B , and the plug device  700  is pulled from the lumen  106  of the artery  104 .  
      Preferably, the plug device  700  is formed from an elastomeric biocompatible material such as silicone. As described above, silicone is useful since it is non-toxic, chemically inert, substantially insoluble in blood and substantially non-immunogenic. In addition to silicone, newer elastomeric biocompatible materials may also be used such as polyurethanes and polyisobutylene-based polymers. Moreover, plug  700  is preferably formed via molding techniques such that the structural elements described above are formed from a unitary piece of material.  
      The plug devices of  FIGS. 5-13C  are designed to provide temporary occlusion of an artery  104 . In other words, they are meant to be easily removed. Such a design is useful in many different surgical procedures that require temporary replacement of an artery. This function is typically provided by a clamp or balloon device.  
      While the present invention has been discussed above in connection with surgical repair of an abdominal aortic aneurysm, it will be apparent to those skilled in the art that it may also be applied to treat other aneurysms, such as abdominal iliac aneurisms, whereby it is required that the supply of blood be cut off to the diseased vessel. III can also be used in other surgical procedures. For example, it can be used to occlude an artery in conjunction with an artery bypass procedure, such as coronary artery bypass, tibial artery bypass which is typically calcified or other vessel bypass procedures. It can also be used as a substitute for modern embolization treatments wherein one of a variety of materials (such as gel-foams, Polyvinyl alcohol material, metal coils, glue), depending on whether vessel occlusion is to be temporary or permanent, is passed through a catheter whose tip lies in or near the vessel to be closed. Such embolization treatments are commonly used to control bleeding from injury (e.g., car accident, gun shot wound, knife wound), a tumor, an ulcer or some other cause on an emergency basis. In addition, such embolization treatments are commonly used to treat arteriovenous malformations (AVMs). In other instances, the plugs of the present invention may be used to occlude arteries in other regions of the body. Furthermore, these plugs may also be used to occlude other blood vessels such as veins and capillaries. The plugs may be utilized in permanent or temporary procedures.  
      There have been described and illustrated herein several embodiments of plugs for occlusion of a blood vessel and methods for the use thereof. While particular embodiments of the invention have been illustrated and described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular materials have been disclosed, it will be appreciated that other materials can be used as well. In addition, while particular sizes of plugs have been disclosed, it will be understood that different sized plugs can be used for use in certain blood vessels. Further, while the plugs have been disclosed with reference to relative direction (e.g., top, bottom, front, rear, etc.), it will be understood that these terms are relative terms and not intended to be limiting with respect to the orientation of the plugs in space. In addition, while the plugs have been disclosed as being provided separately from an insertion device, it will be appreciated that the plugs may be pre-mounted on insertion devices, and sets of plugs and insertion devices may be sold as a kit for a particular surgery. In addition, while it has been disclosed that a thread may be affixed to the plug devices described herein and pulled to thereby remove the plug device from the occluded vessel, it will be appreciated that other material with sufficient tensile strength, such as metal or plastic, can be substituted for this purpose. Numerous other modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art. It will therefore be appreciated by those skilled in the art that those modifications, changes, variations, substitutions and equivalents could be made to the provided invention without deviating from its spirit and scope as claimed.