Abstract:
The invention includes a medical device and more specifically relates to a valve found generally within a frame. In a preferred device, the frame preferably comprises a self-expanding stent frame, and the valve has at least one expandable and contractible pocket member within the stent frame for resisting and permitting fluid flow, respectively.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuation of U.S. patent application Ser. No. 10/457,148, filed on Jun. 9, 2003, pending, which is a continuation of U.S. patent application Ser. No. 10/182,970, filed on filed Jan. 31, 2001, abandoned, which is an National Stage of PCT/US/01/03095, filed on Jan. 31, 2001 and published in English, which claims the benefit of U.S. Provisional Patent Application No. 60/179,195, filed on Jan. 31, 2000. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field of the Invention  
         [0003]     The invention includes a medical device and more specifically to a valve found generally within a frame. In preferred devices the frame is comprised of a radially expandable stent which can be delivered through a delivery device such as a catheter.  
         [0004]     2. Background of the Invention  
         [0005]     Lower extremity venous hypertension in addition to venous insufficiency is a major cause of morbidity in the United States. Symptoms of venous disease include lower extremity edema, varicosities, skin pigmentation changes, skin ulceration, and general poor circulation. One solution to this problem is to replace the defective valve or the vein with a valve assembly.  
         [0006]     Current valves include a pressure responsive, pressure directed ball movement valve assemblies. The problem with mechanical ball valves is that mechanical valves are susceptible to clot formation. Additionally, there are problems associated with long-term wear and tear on the device.  
         [0007]     Artificial valves such as biological valves are also known. Biological valves include homografts, allografts, and xenografts. Problems associated with some biological valves include the supply of the valves, immunity response, or problems associated with matching the size with the donor.  
         [0008]     Finally other problems associated with valve repair include placement problems in which the device cannot be repositioned once it is ejected from the placement catheter, leakage that occurs, around the valve, and emboli formation.  
         [0009]     In light of this background, there remains a need for alternative and improved devices and methods for providing valvular function within vessels of the body. The present invention is addressed to these needs.  
       SUMMARY OF THE INVENTION  
       [0010]     Disclosed is a medical device comprising a frame that has a valve generally located within. In preferred forms of the invention, the frame is comprised of a radially-expandable stent (including especially a self-expanding stent), which can be delivered through a delivery device such as a catheter, and then deployed and expanded at a target site in a body lumen such as an artery or vein. For example, in one preferred use, such a stent and method are used to treat incompetent veins in the legs or feet.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIGS. 1A  to  3  demonstrate one embodiment of the invention comprising a stent.  
         [0012]     FIGS.  4  to  8  demonstrate other embodiments of the present invention comprising the valve.  
         [0013]     FIGS.  9  to  11  demonstrate embodiments that illustrate exemplary ways of attaching a plurality of stents.  
         [0014]     FIGS.  12  to  15  demonstrate exemplary embodiments of the valve configuration in a variety of stent embodiments.  
         [0015]      FIG. 16  demonstrates one aspect of the invention in situ.  
         [0016]     FIGS.  17  to  19  demonstrate other alternative embodiments.  
         [0017]      FIG. 20  depicts a medical assembly of the invention including a stent valve and a delivery device for the stent valve.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     With reference to  FIG. 15 , shown is one embodiment of the present invention. The invention includes a frame such as a wire stent that has a lumen extending therethrough. Near one end of the stent is the valve assembly comprising some leaflets or cusps. A valve opening is generally located between the leaflets through which fluid flows. Although shown as a two leaflet valve, equally the invention can comprise, in any embodiment described herein, at least one leaflet such as two, three or four leaflets.  
         [0019]     With respect to  FIGS. 1A, 1B , and  1 C, a frame is partially shown. The frame can comprise a stent  20 . Choices of stent include a self expanding stent or a non-self expanding stent. In one embodiment of the present invention stent  20  is a self expanding stent such as the Gianturco stent available from Cook Inc. of Bloomington, Ind. as described in U.S. Pat. No. 4,580,568, the entire disclosure of which is expressly incorporated by reference herein. Such stent can be any length, but in one embodiment, the stent is about 15 mm long. Stent  20  includes a plurality of bends  22 , which generally form the area in which the stent struts  24  reverses direction. Bends  22  are generally rounded to provide an atraumatic condition. Since the stent  20  is generally located in a vessel or body lumen of some type, the stent  20  can be cylindrical and therefore has a stent diameter  21  (shown in  FIG. 3 ). In another embodiment, the stent  20  can also have a plurality of connectors  26  that connect adjacent struts  24 . One way to provide a connector  26  is to dispose a solder bead between the adjacent struts. However connector  26  can also be a suture, weld, adhesive, rod, clamp, or other well-known ways to connect adjacent struts  24 . Connector  26  provides several non-critical advantages. Connectors  26  can attach adjacent struts  24  to minimize or prevent flaring of the ends of the stent  20 . Furthermore, connector  26 , if placed near the bend  22 , can create a hole  28  wherein the boundaries of the hole are the wires of the stent operating in general conjunction with the connector  26 . This creates a hole  28  through which a thread or suture can run. However, as shown in  FIG. 1C , a separate prefabricated hole can be created by separately attaching a hole assembly, such as a cap  29  over the bend  22 . In any case, one benefit of the connector  26  or cap  29  is that they increase the radiographic visualization of the invention. Particularly, if the connector  26  is a solder bead, it has increased radiopacity.  
         [0020]     With respect to  FIGS. 2A and 2B , shown is part of the stent in which connector  26  attaches adjacent struts  24 . As mentioned above, a thread or suture can be threaded through the hole  28 . A proximal suture  30  can be sewn through the stent proximal bends  22  or stent proximal ends  31  of the stent. Similarly, a distal suture  32  can be sewn through the stent distal end  33  or the stent distal bends  22  of the stent. One way to thread the suture is shown in  FIG. 2B  wherein the suture  35  (generically any suture) runs over the strut  24  to enter the hole  28 , through hole  28  to come behind the same strut  24 , over the strut  24  and across to the adjacent strut  24  running over the adjacent strut  24 , behind the adjacent strut  24  to come from behind and through hole  28 , and then run subsequently over adjacent strut  24 . Once the struts are connected via the suture, the suture can be pulled to a predetermined tightness to control the overall stent size. Accordingly, the stent can be so constructed to have a predetermined stent perimeter  34 . To this end, the stent lumen  36  will also have an appropriate size. The stent can be constructed so as to have a different perimeter length at the proximal or distal ends.  
         [0021]     With regard to  FIG. 3 , shown is a cylindrical stent  20  that has the proximal and distal sutures running through the bends  22  or holes  28  of the proximal and distal ends of the stent. By altering the tautness of the sutures, the size of the stent lumen  36 , the stent diameter  86 , and the stent perimeters  34 , can be adjusted. As can be seen, distal perimeter suture  32  runs along the stent distal end  33 , whereas proximal perimeter suture  30  runs along the stent proximal end  31 . The respective sutures run through hole  28  of each bend  22 .  
         [0022]     With respect to  FIGS. 4 and 5 , the valve material  38  is shown, in this exemplary embodiment, as a sheet. In so constructing the valve  41 , the valve material  38  is draped across the stent lumen  36  opening (such as shown on the proximal portion of the stent) and then pushed down into the stent lumen  36  itself. Excess material can be kept outside the stent, which will later become a potential fold-over  42 . However, the excess material can also be trimmed off. The valve material  38  is connected to the stent, using for example, distal valve-stent suture  40 . However, any well known ways to connect the valve to the stent is contemplated, such as but not limited to, sutures, adhesives, folds, or the like. In one embodiment shown in  FIG. 5 , the valve-stent suture  40  can share the hole  28  with distal suture  32  near the stent perimeter  34 .  
         [0023]     The valve material  38  can be any biocompatible material such as polyethylene terephalate(PET), polypropylene(PP), polytetrafluorethylene(—PTFE), or any polymer or derivative thereof, and also includes commercially known materials such as GORE-TEX, DACRON, or any other synthetic material. The preferred material  38  will be advantageously compliant and employed so as to permit effective value function as described herein and in the case of collapsible/expandable state devices will retain integrity and function when cycled between tehse states.  
         [0024]     It is preferred to use a biomaterial that serves as a biocompatible scaffold with the ability to remodel host tissue. Accordingly, a naturally occurring biomaterial is highly desirable. One such biomaterial is collagen and more particularly, a collagen based biomaterial called extracellular matrix (ECM). Examples of ECM&#39;s include pericardium, stomach submucosa, liver basement membrane, urinary bladder submucosa, tissue mucosa, dura mater, and small intestine submucosa One such biomaterial is the ECM, such as submucosa, and more particularly is small intestine submucosa (SIS). SIS can be made in the fashion described in Badylak et al., U.S. Pat. No. 4,902,508; Intestinal Collagen Layer described in U.S. Pat. No. 5,733,337 to Carr and in 17 Nature Biotechnology 1083 (November 1999); Cook et al., WIPO Publication WO 98/22158, dated May 28, 1998, which is the published application of PCT/US97/14855; Gastric Submucosa as described in WO 98/26291 (PCT/US97/22729), claiming priority to U.S. Provisional application No. 60/032,686; Liver tissue as described in WO 98/25637 (PCT/US97/22727), claiming priority to 60/032,680; Stomach Submucosa as described in WO 98/25636 (PCT/US97/23010), claiming priority to 60/032,683; and Urinary Bladder Submucosa as described in U.S. Pat. No. 5,554,389; all the disclosures of which are hereby expressly incorporated by reference. Irrespective of the origin of the valve material (synthetic versus naturally occurring), the valve material can be made thicker by making multilaminate constructs, for example SIS constructs as described in U.S. Pat. Nos. 5,968,096; 5,955,110; 5,885,619; and 5,711,969; the disclosures of which are entirely and expressly incorporated by reference.  
         [0025]     With respect to  FIGS. 6A and 6B , shown is the connection of the valve to the stent frame. As described above, the valve can be sutured at the distal portion of the stent using distal valve-stent suture  40 . Similarly, the proximal portion of the valve can be sutured to proximal portion of the stent, and more particularly to proximal perimeter suture  30 . Shown is the valve connected to the proximal portion of the stent at proximal valve-stent suture  44 . Suture  44  can be through a bend  22  or can attach to the proximal perimeter suture  30 . In a traditional Gianturco Z-stent, it is either an 8 (bend) point or 10 (bend) point stent, so one leaflet of the valve can be sutured to the four points of an 8 point stent thereby comprising one half of the stent. To provide further integrity, the valve can be sutured at the proximal and distal end to the perimeter sutures themselves, without actually being sutured to any or all of the stent bends  22 .  
         [0026]     With respect to  FIG. 6B , shown is the valve with the stent frame removed. Once the sutures are generally in place, the valve sheet  38  will form a valve pocket  46 , extending inside the stent lumen in which the fluid will fill. Proximal valve perimeter  48  will have the sutures connecting the valve to the stent (not shown). Once the distal sutures are in place, the general shape will likely resemble a pocket with the pocket having a valve apex  50 . There is a part of the valve that will form central valve portion  49  that is not directly sutured to the stent. This valve portion  49  will form the valve opening  52  through which fluid will pass. Thus, upon filling of the valve pocket  46 , the fluid pressure will exert outwards causing valve portion  49  to extend outward. When it does, it will contact the other leaflets or cusps and form a seal to stop or impede fluid flow.  
         [0027]      FIG. 7  shows a top view of the stent valve. In this particular non-limiting view, shown is the valve opening  52  in a slightly open configuration. Valve pockets  46  are shown in a slightly distended configuration. The valve is connected, for example, by sutures to the stent perimeter  34  and also forms a valve perimeter  48 . Because of the opening and closing of the valve, there may be increased wear and tear at the valve-stent-opening connection. At this point, one embodiment of the present invention provides a reinforcement at this point. For example, this reinforcement can be a plurality of reinforcement sutures  54 , adhesive, another material, or any other mechanism that permits increased structural integrity.  
         [0028]      FIG. 8  demonstrates a view of the stent valve once the distal portion of the valve is sewn to a distal bend  22  and also shows the proximal portion of the valve being connected to the proximal portion of the frame with one suture in the foreground, one suture in the background. In addition, the reinforcement suture  54  is found in the foreground. Although only two sutures  44  are seen at the proximal portion, it is of course well-understood that some or each of the proximal bend of the frame can be connected to the proximal portion of the valve. Similarly, although only one distal suture  40  is shown, there may be as many distal sutures necessary to connect the valve apex  50  or the distal portion of the valve to the frame. It is well understood that this may be just one distal suture or many distal sutures. Varying the number of distal sutures will vary the shape, tightness, and overall configuration of the valve, valve pocket  46 , and the valve apex  50 .  
         [0029]     The valve opening  52  although already described above, is actually created in the final step of preparation of the preferred device manufacture. The construction mentioned above would be repeated on the other side of the valve to create the valve pocket  46 , valve apex  50 , and the like on the other side. At this point, though, there is no valve opening  52 . The valve opening  52  is created by creating a slit in the sheet to create the opening. The slit can be sized according to the intended flow rate of the passing fluid. Accordingly, a large slit would create a large valve opening or orifice and permits a large volume of fluid to pass therethrough. The slit can be created by poking a scalpel through it and running it to the desired length. However, due to potential fatigue at the orifice, another set of reinforcements may be added to the orifice perimeter. Therefore, as shown in  FIGS. 7 and 8 , an orifice reinforcement  53  may be created by any known conventional ways, such as sutures (resorbable or non-resorbable), adhesive, string, staples, rings, or the like.  
         [0030]     Therefore, the stent valve as constructed can be using one stent with the valve material enclosed therein. Of course in the single stent configuration, the overall length can be adjusted by elongating the length of the struts  24 . However, devices of the invention can be built using a plurality of stents to elongate the overall size of the stent, if desired. In this regard, it will be preferred that the length of the device  20  is sufficient to provide an aspect ratio (length to expanded diameter) sufficiently high to facilitate proper alignment of the device  20  within the vessel, with the axis of the device lumen generally aligned with the axis of the vessel. For example, devices having a ratio of length:expanded diameter of 1:1 or greater, or about 2:1 or greater, will be preferred. It will be understood that while such dimensions will advantageously facilitate placement of the inventive devices, they are not necessary to the broader aspects of the invention.  
         [0031]     With reference to  FIG. 15 , shown is a double stent structure with the valve. Returning now to  FIG. 9 , shown is a first stent  58  and a second stent  60 . For the purposes of discussion only, first stent  58  is shown to be atop of the second stent  60 . Ultimately as shown herein by way of example only, the valve will reside in the first stent  58 . It should be noted however that the valve can reside in the second stent  60  also as shown in  FIG. 17 . Furthermore, the overall length can be increased by joining several stent valves together as shown in  FIGS. 18 and 19 , thereby having a plurality of stents, such as a first stent  58 , second stent  60 , and a third stent  61 . The valve  41  can be placed in any or all stents, in any combination, for example, as shown by the dotted lines. In this regard, it is suggested and intended that many stents can be joined and that each or any stent may house a valve or plurality of valves. One benefit of having a plurality of stents is that upon ejection of the placement device, the invention will provide a self-aligning feature in the vessel. This is because the plurality of stents is generally longer with respect to the stent diameter, or the plurality of valve device(s), as discussed above.  
         [0032]     Manufacture of the multi-stent or multi-valve device will generally follow the same construction as described above. The same considerations in making a single valve single stent device applies equally to the elongated device.  
         [0033]     Returning now to  FIGS. 9 and 10 , shown are methods of connecting the first stent  58  and second stent  60 . Equally, the construction shown from now on also includes construction of at least two stents or at least two valves. First stent  58  and second stent  60  has bends  22  that are adjacent each other. Shown in  FIG. 9  is where the first stent  58  has its bends beside the bends of the second stent  60  such that they are not touching each other (although they may touch). They are connected together in the manner described above, and for example by stent-stent suture  56 . Stent-stent suture  56  can be resorbable or non-resorbable. This suture travels through the distal bends of the first stent  56  and the proximal bends of the second stent  60 . The suturing pattern can be that described in  FIG. 2B  and the accompanying discussion. As shown in  FIG. 10 , the bends can be juxtaposed over each other to provide an overlap such that the stent-stent suture  56  will go through the bends at the same time. Therefore, the construction contemplates that the stent bends may touch, overlap, or not at all.  
         [0034]      FIG. 11  shows one embodiment of the present invention in which the valve apex  50  is sutured to at least three bends: two bends of the first stent  56  and one bend of the second stent  60 . In this regard, the valve also operates to keep the first stent  56  partially connected to the second stent  60 . From the bends, a plurality of valve apex sutures  66  are seen. These sutures can emanate from the bends and each bend can have many valve apex sutures  66  that travel in many directions. Using multiple valve apex sutures  66  that emanate in many directions and using a plurality of bends (from either stent), generally functions to minimize any parachuting or inversion of the valve pocket  46 .  
         [0035]      FIG. 12  demonstrates a top view of the multi-stent device in which the valve opening  52  is seen (in a closed position) and the valve pocket  46  and valve apex  50  is connected to three bends. Again it should be understood that many sutures may emanate from many bends from any stent.  
         [0036]     As described earlier, the excess material can either be trimmed off or folded over the outer surface of the device. Shown in  FIGS. 13A and 13B , is the excess material being folded over the device and attached at the distal end of the first stent  58 . Shown in dotted lines is the first stent  58 .  FIG. 13B  shows that the fold-over  42  provides a second material outer sheath so that the suture passes through the inside and outside material to increase structural integrity. Also, by folding over the excess material, a smoother surface is presented rather than the naked frame of the tip of the bend.  
         [0037]     In all embodiments of the invention, the external surface of the frame can be covered with a sheath that is not necessarily the same material as the valve  41 . For example, while the valve can be a naturally occurring material, the outer sheath can be synthetic material such as described herein. The sheath, therefore, can be the fold-over of the valve material, another type of naturally occurring material, or a synthetic material. Accordingly, the sheath may partially or totally cover the frame.  
         [0038]      FIG. 14  shows an embodiment in which both the first stent  58  and second stent  60  are covered by the fold over  42 . Here, the fold-over  42  is connected to the distal portion of the second stent  60 . In this manner, the entire device may be covered with an outer sheath of biomaterial. The benefit of doing so, especially if using SIS or other similar ECMs, is that the regrowth and endothelialization of the device embeds and encapsulates the frame. Accordingly, there is a reduced risk of device migration. Furthermore, due to the remarkable remodeling properties of SIS, the outer SIS sheath acts as a conduit for host tissue to infiltrate the device and remodel the valve itself. Over the course of months, the valves are replaced by host tissue and the SIS disappears.  
         [0039]      FIG. 15  shows yet another embodiment of the present invention. In this demonstration, the valve is located in the first stent  58 , sutured at the proximal end at the stent perimeter. The valve apex  50  is sewn somewhat proximal of the stent-stent suture  56 . The valve apex  50  is sewn at the valve apex sutures  66  to an intermediate portion of the frame. To minimize parachuting or inversion, a valve intermediate portion  75  may be sutured using valve intermediate suture  76  to connect the valve to the frame. In addition, the valve may be so constructed to extend the valve&#39;s length to create an elongated valve pocket  90  (shown by the dotted lines). While the extended pocket  90  can be connected to the distal perimeter of the second stent distal suture  62 , it can also be connected to an intermediate portion of the second stent.  
         [0040]     With further reference to  FIG. 15 , it is seen that the valve opening  52  is a slit that extends across the first stent diameter  21  but terminates several millimeters before reaching the edge. In some embodiments, this distance could be 1-5 mm from the edge. Of course, it is understood that the invention contemplates any distance that varies the length of the slit. Also, shown in  FIG. 15 , but equally applies to any device described herein, is an anchor  92 , which can be anchor barbs  92 . These barbs  92  can dig into the adjacent vessel wall to relatively affix the device at its location. Anchor  92 , although shown as barbs, may include hooks, adhesives, knobs, a textured surface, or any other treated surface that facilitates relative affixation of the device in its location. Similarly, the outer surface of the fold-over or sheath can be so configured to provide anchoring.  
         [0041]      FIG. 16  demonstrates the device upon implantation into the patient. Upon implantation the device generally resides in a vessel  80 . For example, the vessel could be vein, artery or the heart or wherever a valve is necessary. In one preferred use, the vessel is an incompetent vein in the leg or foot of a patient. The device  20  reduces or prevents retrograde blood flow, while normal blood flow is permitted to travel through device  20 . Illustrative veins in which the device  20  may be used include, for example, saphenous veins, femoral veins, popliteal veins, tibial veins, and the inferior vena cava.  
         [0042]     The vessel  80  has an inner lumenal surface  82  in which the fluid flows. The fluid flow path is shown as fluid path  70 . Vessel  80  also has a vessel diameter  84 . The medical device, upon implantation, will also have a device outer stent diameter  86 . The outer diameter  86  will be chosen to permit contact with the inner lumenal surface  82 . The optimized fit will decrease the leakage around the device by contacting the inner lumenal surface  82 . A tight fit can be accomplished by sizing the stent diameter to be greater than the vessel diameter. For example, a stent diameter that is about  110  percent greater than (i.e. 1.1 times) the vessel diameter provides a good fit. Expanded stent diameters of about 10 mm to about 30 mm will be typical in many applications of the present invention. Again, while it is shown in this  FIG. 16  that the valve is located in the first stent  58  and only the first stent  58  is covered by the fold-over  42  or sheath, it should be remembered that the valve could be located in the second stent  60 . Similarly, the fold-over  42  or sheath could extend onto the second stent  60 .  
         [0043]     The standard method of deploying the medical device  20  in a vessel  80  involves the use of a medical assembly (see  FIG. 20 ) including the device  20  and a delivery device such as a percutaneous delivery device, e.g. a catheter  100 . The frame is configured to a contracted state, e.g. by resiliently forming the frame into a contracted configuration, to load into the delivery device (catheter). The catheter can be introduced into the patient via a suitable approach, for example through the jugular or femoral vein. To advance and deploy the device from the distal end of the delivery catheter, a pusher  101  is placed into the catheter lumen. When the device  20  is fully deployed, it assumes the second, expanded configuration within the vessel  80  as depicted in  FIG. 16 . The stent frame, being made of resilient material, conforms to the shape of the vessel wall such that when viewed on end, the device  20  has a circular appearance when deployed in a round vessel.  
         [0044]      FIGS. 17, 18 , and  19  show other described embodiments.  FIG. 17  demonstrates the valve  41  in the second stent  60 . In this embodiment, the valve apex  50  is connected to the second stent&#39;s distal perimeter.  FIG. 18  demonstrates at least two stent frames connected together. In this particular embodiment, the valve is located in the first stent  58 , with the valve apex  50  being connected at the first stent 58-second stent  60  junction. In dotted lines, however, there may be many stents, such as first stent  58 , second stent  60 , and third stent  61 . The valve  41  may be found in any of the stents or in all. Similarly, in the three stent configuration, the valve may begin at the first stent and have the valve apex  50  be generally located in the third stent  61 .  FIG. 19  shows another embodiment of the present invention in which the valve  41  begins in the second stent  60  and extends into the third stent  61  thereby having the first stent  58  being empty.  
         [0045]     Finally, since the device is located in an in vivo environment, the device may be treated with therapeutic agents to facilitate healing. For example, the frame may be treated with therapeutic agents such as anticancer drugs, plaque busters, anti-coagulants, or the like. Similarly, the valve material can be treated with therapeutics agents such as anti-cancer drugs, plaque busters, anti-coagulants, proteins, growth factors, proteoglycans, and the like. Furthermore, radiopaque agents may be added, such as tantalum, barium, bismuth, or the like to increase radiopacity. These ingredients can be bonded to the frame or the valve material such as rubbing the agent in, bonding it, adhering it, or the like.  
         [0046]     While the invention has been illustrated and described in detail in the drawings and the foregoing text, it is understood that these are only some embodiments and that the scope of the invention is not solely defined by the description herein but also by the appended claims. All modifications and changes that come within the spirit of the invention are hereby protected.