Abstract:
A replacement venous valve comprises a pair of support wings and a pair of valve wings. The valve wings are designed to deploy first from a catheter deployment device and provide stability while the support wings then deploy. The valve wings support the venous valve material and the support wings maintain patency of the vein above the valve while simultaneously anchoring the location and orientation of the valve.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to venous valve replacement and, in particular, to replacement venous valves to lower extremities and a therapeutic method of treating venous circulatory disorders.  
         BACKGROUND OF THE INVENTION  
         [0002]    Chronic venous insufficiency (CVI) of the lower extremities is a common condition that is considered a serious public health and socioeconomic problem. In the United States, approximately two million workdays are lost each year, and over 2 million new cases of venous. thrombosis are recorded each year. About 800,000 new cases of venous insufficiency syndrome will also be recorded annually. Ambulatory care costs of about $2,000, per patient, per month, contribute to the estimated U.S. cost of $16,000,000 per month for the treatment of venous stasis ulcers related to CVI.  
           [0003]    It is estimated that greater than 3% of the Medicare population is afflicted by a degree of CVI manifested as non-healing ulcers. Studies have indicated that about 40% of seriously affected individuals cannot work or even leave the house except to obtain medical care: It is estimated that 0.2% of the American work force is afflicted with CVI.  
           [0004]    Chronic venous insufficiency arises from long duration venous hypertension caused by valvular insufficiency and/or venous obstruction secondary to venous thrombosis. Other primary causes of CVI include varicosities of long duration, venous hypoplasia and arteriovenous fistula. The signs and symptoms of CVI have been used to classify the degree of severity of the disease, and reporting standards have been published. Studies demonstrate that deterioration of venous hemodynamic status correlates with disease severity. Venous reflux, measured by ultrasound studies, is the method of choice of initial evaluation of patients with pain and/or swelling in the lower extremities. In most serious cases of CVI, venous stasis ulcers are indicative of incompetent venous valves in all systems, including superficial, common, deep and communicating veins. This global involvement affects at least 30% of all cases. Standard principles of treatment are directed at elimination of venous reflux. Based on this observation, therapeutic intervention is best determined by evaluating the extent of valvular incompetence, and the anatomical distribubon of reflux. Valvular incompetence, a major component of venous hypertension, is present in about 60% of patients with a clinical diagnosis of CVI.  
           [0005]    Endovascular valve replacement refers to a new concept and new technology in the treatment of valvular reflux. The concept involves percutaneous insertion of the prosthetic device under fluoroscopic guidance. The device can be advanced to the desired intravascular location using guide wires and catheters. Deployment at a selected site can be accomplished to correct valvular incompetence. Percutaneous placement of a new valve apparatus provides a less invasive solution compared to surgical transposition or open repair of a valve.  
           [0006]    The modern concept of a stent was introduced in the 1960s. Subsequently, it has been successfully incorporated in the treatment of arterioral aneurysms and occlusive disease. The use of endovascular stents represents one of the most significant changes in the field of vascular surgery since the introduction of surgical graft techniques in the early 1950s.  
           [0007]    Initially, the dominant interest of vascular specialists was application of stents in the arterial system. The venous system and venous disease were not considered an arena for stent application. The utilization of endovascular treatment in venous disease was initially confined to the treatment of obstruction, in the pelvic veins (for CVI) as well as treatment of obstructed hemodialysis access grafts and decompression of portal hypertension (TIPS). Although these procedures enjoy widespread application, the actual number of patients involved is relatively low compared to the number afflicted with CVI and related syndrome. Thus, the necessity for therapy using endovascular technology for the treatment of venous disease arose. The prevalence of CVI and the magnitude of its impact demand development of an effective alternative therapy.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    A replacement venous valve comprises a pair of support wings and a pair of valve wings. The valve wings are designed to deploy first from a catheter deployment device and provide stability while the support wings then deploy. The valve wings support the venous valve material and the support wings maintain patency of the vein above the valve while simultaneously anchoring the location and orientation of the valve. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a schematic depiction of the frame of one embodiment of a replacement valve.  
         [0010]    [0010]FIG. 2 is a generally top perspective view of one embodiment of the replacement valve.  
         [0011]    [0011]FIG. 3 is a schematic side section view of a replacement valve in a vein.  
         [0012]    [0012]FIG. 4 is a schematic side view of one embodiment of the angular relationship of a replacement valve structure in a vein.  
         [0013]    [0013]FIG. 5 is a side section view of a compressed, non-deployed replacement valve in a delivery system component.  
         [0014]    [0014]FIG. 6 is a schematic side section view of a venous valve being localized prior to release in a vein.  
         [0015]    [0015]FIG. 7 is a schematic side section view of the valve wing release opening of a venous valve in a vein.  
         [0016]    [0016]FIG. 8 is a schematic side section view of the stabilizer wing release of a venous valve in a vein.  
         [0017]    [0017]FIG. 9 is a schematic side section view of a venous valve being localized prior to release in a vein.  
         [0018]    [0018]FIG. 10 is a schematic side section view of the valve wing release of a venous valve in a vein.  
         [0019]    [0019]FIG. 11 is a schematic side section view of the valve wing positioning and release of the stabilizer wing in a venous valve in a vein.  
         [0020]    [0020]FIG. 12 is a schematic side section view of the valve wing positioned and the stabilizer wing being deployed in a venous valve in a vein.  
         [0021]    [0021]FIG. 13 is a schematic side section view of the valve wing and stabilizer wing fully deployed in a vein.  
         [0022]    [0022]FIG. 14 is a schematic side section view of the valve functioning in position in a vein.  
         [0023]    [0023]FIG. 15 is an assembly view of an alternate embodiment replacement valve design. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    Within the field of endovascular treatment, no previous technology has effectively used a replacement valve which also acts similar to a self-righting stent in a percutaneously located assembly. Indeed, recognition of the need for such a device, system and method of employment has been lacking. Attempts at venous valve repair are not common. Indeed, minimally invasive repair or replacement procedures are quite uncommon. This is due, in part, to the poor availability of properly sized and properly designed prosthetic venous valves. U.S. Pat. No. 5,500,014 has an excellent discussion of the different attempts to provide prosthetic venous valves, and such discussion is incorporated by reference herein. For the anatomy of venous valves, an excellent reference includes Venous Valves, by R. Gottlub and R. May, published by Springer Verlag, Austria, 1986.  
         [0025]    The inventors have devised a device, system and method of deployment for a valve assembly utilizing various materials having excellent cost, biocompatibility, and ease of use. In one embodiment, a stent is assembled having excellent length and stability characteristics, as well as an improved profile for ease of placement and automatic deployment at a deployment site. The assembly does not rely only on placement at a previous valvular site but may also be utilized either proximal or distal to the incompetent valve site due to the self-expanding and self-orienting features and improved anti-migration characteristics of the assembly.  
         [0026]    The use of the material chosen for endovascular valve leaflet portions of the replacement valve of this assembly may be selected from a variety of biocompatible substances Whether the material is formed of elastomer, sclera, small intestine sub-mucosa (SIS), other mammalian tissue, or other suitable material, the venous stent device of this invention may serve as a substitute for deteriorated venous valves which have been altered by thrombosis or congenital hypoplasia. The valve prosthesis which self-expands similar to a stent will be percutaneously introduced with a small sized catheter delivery system, but demonstrates improved self-righting and orienting within the vein.  
         [0027]    Justification for development of this invention is based on the incidence of venous disorders that lack adequate endovascular therapy. Patients who are treated surgically undergo a more invasive method that involves greater costs and more numerous potential complications. The minimally invasive technique of this invention will decrease length of hospital stay, lower over-all costs and permit an almost immediate return to normal activity. Indeed, it is believed that the availability of this treatment will dramatically alter the lives of many people, including those who might not have been able to undergo previous surgical techniques for the repair or replacement of damaged venous valves.  
         [0028]    [0028]FIG. 1 is a schematic depiction of one embodiment of venous valve assembly  20  with a frame having a first support wing  21 , an opposite second support wing  24 , a first valve wing  22  with its opposite second valve wing  23 . The first interlink  25  joins the support wings  21 ,  24  with the valve wings  22 ,  23  at a first junction. A second interlink  26  joins the support wings  21 ,  24  with the valve wings  22 ,  23  at a second junction. Valve  20  is preferably of unitary, single wire construction, but alternate configurations having a plurality of wires are possible.  
         [0029]    [0029]FIG. 2 shows a venous valve assembly  20  with a first valve leaflet or flexible sheet  30  and a second valve leaflet or flexible sheet  34  with aperture  32  between the flexible sheets. It is recognized that, in operation, aperture  32  includes trailing edge portions  35  which open and closes as valve leaflets respond to the pressure and pumping action of the blood through the valve. As shown in FIG. 3, first support wing  21  and second support wing  24  provide lateral stability by exertion of outward radial force in the form of a support ring exerting outward pressure against the inner lumenal wall  44  at a venous location for the valve. In similar manner, the valve wings  22 ,  23  exert similar force in the form of a valve ring force exerted outwardly against the lumenal wall  44 , and provide similar stabilizing and self-righting advantage to the valve as will be further discussed.  
         [0030]    [0030]FIG. 4 illustrates the approximate included angle desired between each support wing  21  and each valve wing  23  as generally about 60°+/− about no more than 10° and preferably only about +/− a maximum of about 5°, and between first valve wing  23  and second valve wing  22  as their ends push into vein wall  44 .  
         [0031]    [0031]FIG. 5 illustrates the folding of the venous valve stent  20  to a closed position within a deployment system device  50 . It is shown how the respective valve and support wings fold compactly together in an overlapping, butterfly-like relationship.  
         [0032]    [0032]FIG. 6 illustrates the folded venous valve stent  20  inside a delivery system device  50 , such as a catheter. FIGS. 7 and 8 further illustrate the deployment sequence of the replacement valve stent  20  in relation to a vein wall  44 . The venous valve  20  is pushed toward the delivering end of the delivery system  50  until the first valve wing  23  and the second valve wing  22  spring open and engage the vein lumenal wall  44 . The delivery system  50  is withdrawn after the venous valve wings are in the desired position. With the delivery system  50  separated from the venous valve stent  20 , the first support wing  21  and the second support wing  24  then engage the vein wall  44 .  
         [0033]    [0033]FIGS. 9-14 are simpler schematic depictions of the steps of delivering the venous valve stent  20  into a vein. The final step illustrates the position of the venous valve stent in relation to blood flow arrows and depicts the functionality of the valve leaflets.  
         [0034]    [0034]FIG. 15 is an assembly sequence view of another embodiment of a venous valve assembly  200  in which the first support wing  140  is conjoined with the first valve wing  150  to form half of venous valve assembly  200 . The second support wing  160  is conjoined with second valve wing  170  to form the other half of venous valve assembly  200 . The two halves are attached by connectors  180  at opposite locations on the frame. The last sequence view in this figure shows the connected halves with first valve leaflet or flexible sheet  300  and second valve leaflet or flexible sheet  340  attached to the valve wings thereby forming aperture  320  with trailing edges  350  in operation.  
         [0035]    Because numerous modifications may be made of this invention without departing from the spirit thereof, the scope of the invention is not to be limited to the embodiments illustrated and described. Rather, the scope of the invention is to be determined by the following claims and their equivalents.