Abstract:
Disclosed are an instrument, valve prosthesis and procedure for the minimally invasive implantation of a sutureless anti-reflux valve in a patient for the treatment of gastroesophageal reflux disease. A prosthesis is provided that comprises a cylindrical housing, a mounting ring and a one-way anti-reflux valve depending from the mounting ring. The cylindrical housing is constructed of a memory material that can be fixed in the gastroesophageal junction. The mounting ring and the anti-reflux valve are fixed within the housing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a division/continuation-in-part of my earlier copending application Ser. No. 08/987,693, filed Dec. 9, 1997, now U.S. Pat. No. ______, which is hereby incorporated herein by reference in its entirety.  
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    This invention relates to a device and non-invasive surgical method for treating gastroesophageal reflux disease. More specifically, it relates to an anti-reflux valve prosthesis and associated instrumentation for its peroral placement and in situ fixing at the gastroesophageal junction, to prevent the reflux of gastric contents into the esophagus in the treatment of gastroesophageal reflux disease in a patient.  
           [0003]    Gastroesophageal reflux disease (GERD) is the commonest cause of dyspepsia, affecting some 30% of the United States adult population intermittently and some 10% on a continuous and troublesome basis. Gastroesophageal reflux disease produces heartburn, abdominal pain and regurgitation of acid-containing gastric contents into the esophagus and pharynx. It may also lead to alteration of the lining of the esophagus (Barrett&#39;s Esophagus), which may go on to produce esophageal cancer. Current methods of treating GERD include powerful antacid medication therapies and surgical interventions.  
           [0004]    Medication therapy with powerful antacids is directed at treating the symptoms of GERD, and is necessarily not curative. Furthermore, medication-based therapies are not always fully effective, as reflux is not prevented and the esophagus may continue to be exposed to gastric content.  
           [0005]    Surgical intervention typically involves either open surgery (performed through the abdomen or the chest) or laparoscopic surgery (performed through one or more incision access ports inserted through the abdominal wall), and the re-sectioning of tissue or the implanting of a prosthetic device. Although surgical interventions can be curative, these treatments are seriously invasive and have the attendant risk of such procedures. Despite the risk, the field has been motivated to provide solutions to the GERD problem, which has resulted in the development of a number of surgically implantable anti-reflux valve prosthetic devices. Prior anti-reflux valve prostheses are essentially one-way valves implanted at the gastroesophageal junction using open or laparoscopic surgery. The implanted prosthesis allows normal swallowing to take place in an orthograde manner while preventing the reflux of gastric contents from the stomach into the esophagus.  
           [0006]    Examples of surgically implanted esophageal anti-reflux valve prostheses include the devices of: Godin (U.S. Pat. No. 5,314,473) which discloses a one-way, antivalve comprising a flattened tubular part associated with an annular fixing element; and Reich (U.S. Pat. No. 4,846,836) which discloses a bi-directional valve and housing for similar purposes. These devices were developed to be inserted into the gastro-esophageal junction via open or laparoscopic surgery and fixed there. The purpose was to permit the unidirectional passage of ingested materials into the stomach while preventing the reflux of gastric content of the stomach into the esophagus. Typically, these devices require suturing or other means to fix them to the tissue of the esophagus.  
           [0007]    Generally, all of these prior devices and methods require surgical invasion of a body cavity and breach of the body membrane in some fashion (e.g., open surgery or laparoscopy) in order to accomplish their utility. However, such invasive surgical interventions are too frequently complicated by problems such as stricture formation, “gas bloat,” or recurrent symptoms of reflux disease. Additionally, the results obtained by gross surgical treatment can be technique-dependent and vary significantly from surgeon to surgeon.  
           [0008]    In view of the preference for minimally invasive forms of surgery there is a need in the art for GERD treatments that can be fully accomplished without surgically compromising the integrity of a patient&#39;s body membrane. Applicant has invented a peroral procedure for the insertion and implantation of a sutureless anti-reflux valve prosthesis that can address this need. It benefits the field to have an alternative prosthetic device and method that can be practiced to position and fix an anti-reflux prosthesis in place in the esophagus without resort to surgical incision or laparoscopy.  
         SUMMARY OF INVENTION  
         [0009]    The present invention relates to an anti-reflux valve prosthesis system for treating gastroesophageal reflux disease (GERD) in a patient, which does not require open or laparoscopic surgery to implant. The present invention provides for perorally inserting a sutureless anti-reflux valve prosthesis down the lumen of the esophagus, to the gastroesophageal junction, where it is fixed in place. The advantage of this system is that peroral insertion of such a valve eliminates the need for either open formal laparotomy, thoracotomy or a laparoscopic approach using multiple access ports. Peroral installation of an anti-reflux prosthesis has the potential benefit of reducing the trauma, morbidity and hospital stay associated with implantation of anti-reflux valve prostheses relative to other surgical techniques. Furthermore, a system permitting the implantation of a standardized anti-reflux valve in an accurate and reproducible manner has the potential for providing more consistent clinical results than can be achieved with other techniquemethods of treatment.  
           [0010]    A preferred embodiment of the present invention provides a prosthesis comprising a cylindrical housing, a mounting ring and a one-way anti-reflux valve. The cylindrical housing is constructed of a memory material that can be fixed in the distal esophagus. The mounting ring and the anti-reflux valve are fixed within the housing.  
           [0011]    Similar cylindrical devices have been used (without the incorporation of an anti-reflux valve prosthesis) in the treatment of strictures due to esophageal cancer. An example of such a device is the WALLSTENT® esophageal endoprosthesis (Schneider USA, Inc.). These devices typically comprise a cylinder of memory metal in close contact with a sleeve of suitable material, such as silicone. The prosthesis is inserted perorally and positioned using an adaptation of the usual tool used for installing similar cylindrical devices. The prosthesis is fixed in place by the expansion of the cylindrical device housing the anti-reflux valve.  
           [0012]    Another embodiment of the present invention provides an anti-reflux prosthesis comprising a cylindrical housing having an enlarged upper end, an optionally enlarged or bell-shaped lower end, and an interior defined by an interior wall. The cylindrical housing is constructed of a memory material having a normal cross-section. When a force, applied to the housing to make the cross-section small, is removed, the housing returns to its normal cross-section, or is expandable to its normal cross-section, e.g. by a balloon. A mounting ring is fixed to the interior wall of the upper end of the housing. Depending from the mounting ring within the interior of the cylindrical housing is a one-way valve. The present invention further comprises an optional anti-inversion support having two ends, one end of which is fixed to a lower end of the one-way valve and the other end of which is fixed to the wall of the lower end of the cylindrical housing.  
           [0013]    Another aspect of the invention is the provision of a system for peroral insertion and mounting of the ant-reflux valve prosthesis in the gastroesophageal junction. The system includes an overtube for holding the cylindrical housing in a radially compressed condition at a distal end of the overtube for peroral insertion down an esophageal lumen. A stylet indwelling in the overtube is in releasable operative engagement with the housing to eject the housing from the distal end of the overtube. A balloon is preferably disposed at a distal end of the stylet within the cylindrical housing, wherein the balloon is in fluid communication with a central longitudinal passage in the stylet for introducing fluid into the balloon to facilitate expansion of the housing to its normal cross-section following ejection of the housing from the overtube, and for removing said fluid from the balloon to allow retraction of the balloon from the housing into the overtube.  
           [0014]    In a further aspect, the invention provides a method for perorally implanting an anti-reflux valve prosthesis. The method comprises: (a) perorally inserting the anti-reflux valve prosthesis described above in a radially compressed condition down the esophageal lumen; (b) positioning the compressed anti-reflux valve prosthesis near the esophageal junction; and (c) expanding the anti-reflux valve prosthesis to normal cross-section to implant said prosthesis in the esophageal junction. The insertion is preferably effected with the valve prosthesis in an overtube, the positioning preferably includes ejecting the valve prosthesis from the overtube, and the expanding optionally comprises inflating a balloon inside the valve prosthesis.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0015]    [0015]FIG. 1 is a perspective view of a preferred embodiment of the self-anchoring valve prosthesis showing a metal mesh memory material housing containing an antivalve.  
         [0016]    [0016]FIG. 2 is a perspective view of the one-way valve from FIG. 1 as seen from the lower end thereof along the lines  2 - 2 .  
         [0017]    [0017]FIG. 3 is a perspective view of the valve used in the prosthesis of FIG. 2 as seen from the side.  
         [0018]    [0018]FIG. 4 is a perspective view of an alternate embodiment of the self-anchoring valve prosthesis of FIG. 1, further showing a series of barbed spikes attached to a mounting ring.  
         [0019]    [0019]FIG. 5 is a perspective view of another alternate embodiment of the self-anchoring valve prosthesis of FIG. 1, further showing a series of uniform spikes attached to a mounting ring.  
         [0020]    [0020]FIG. 6 is a perspective view of a further alternate embodiment of the self-anchoring valve prosthesis of FIG. 1, showing the wire mesh bent into a series of radially extending wires that function as anchoring spikes.  
         [0021]    [0021]FIG. 7 is a perspective view of yet another alternate embodiment of the self-anchoring valve prosthesis of FIG. 1, further showing a series of spikes affixed to the lower end of the prosthesis.  
         [0022]    [0022]FIG. 8 is a cross-sectional view showing the valve prosthesis of FIG. 1 in an insertion tool disposed in the lumen of a patient&#39;s esophagus in an initial implantation step.  
         [0023]    [0023]FIG. 9 is a cross-sectional view showing the valve prosthesis of FIG. 8 ejected from the distal end of the insertion tool and disposed in the lumen of a patient&#39;s esophagus at the gastroesophageal junction in a first intermediate implantation step.  
         [0024]    [0024]FIG. 10 is a cross-sectional view showing the valve prosthesis of FIG. 9 positioned in the gastroesophageal junction and being expanded with an inflated expansion balloon in a second intermediate implantation step.  
         [0025]    [0025]FIG. 11 is a cross-sectional view showing the valve prosthesis of FIG. 1 implanted in the gastroesophageal junction.  
     
    
     DETAILED DESCRIPTION  
       [0026]    As exemplified by the figures, the present invention provides a peroral prosthesis system for treatment of gastroesophageal reflux disease (GERD) in a patient comprising an anti-reflux valve prosthesis, and a peroral implantation tool for perorally inserting and positioning the valve prosthesis at the distal end of the lumen of the esophagus, and implanting or fixing the valve prosthesis to the lumen wall.  
         [0027]    Referring to FIG. 1, in a preferred embodiment, the present invention provides a valve prosthesis  81  comprising a generally cylindrical housing  83  having a bell-shaped upper end  83   a , a bell-shaped lower end  83   b , and a central bore  83   c . The upper end  83   a  and the lower end  83   b  of the cylindrical housing  83  are used by the prosthesis  81  to engage the lumen of the esophagus (see FIG. 11), and the inner diameter or central bore  83   c  of the cylindrical housing  83  is compatible with orthograde passage of ingested (or swallowed) material through the lumen of the esophagus.  
         [0028]    The cylindrical housing  83  is constructed of a memory material that allows the cylindrical housing  83  to be acted upon and deformed, but to return to its original shape when the deformation force is removed. The cylindrical housing  83  is deformed during installation of the prosthesis  81  (see FIG. 8), but returns to its original shape upon release, or is expandable by a balloon, for example, to its original shape (see FIGS.  9 - 10 ). In a preferred embodiment of the present invention, the memory material comprises a metal wire mesh. The exterior surface of the metal mesh facing the esophageal wall preferably has a textured surface to promote adhesion and facilitate anchoring of the prosthesis  81  to the adjacent esophageal wall, while the interior surfaces are preferably smooth and/or hydrophobic to facilitate the orthograde passage of food and liquids therethrough. Thus, the exterior of the metal mesh can be made of or coated with microporous ceramic such as apatite, for example, hydroxyapatite, open- or closed-cell elastomer foams such as polyurethane, for example, or the like. Smooth materials for the interior surfaces of the metal mesh generally include silicone, polytetrafluoroethylene and the like.  
         [0029]    A mounting ring  13  is fixed to the interior wall of the upper end  83   a  of the cylindrical housing  83 . Preferably, the mounting ring  13  is constructed of the inner coating material (such as silicone) or encased or encapsulated in a suitable biologically and chemically compatible or inert material such as silicone or the like. Suspended from the mounting ring  13  within the interior of the cylindrical housing  83  is a one-way valve  21 . The one-way anti-reflux valve  21  permits the easy passage of ingested material through the bore of the cylindrical housing  83  in one direction, while impeding the reflux of stomach content through the bore of the cylindrical housing  83  in the other direction.  
         [0030]    In the embodiment seen in FIGS. 2 and 3, the valve  21  includes a sleeve  89  depending from the mounting ring  13 . The sleeve  89  can be made of a biologically compatible rubber or silicone material, and preferably includes a plurality of rigid or semi-rigid longitudinal stays  87  longitudinally embedded within the material of the sleeve  89  or securely fixed on either the interior or exterior surface thereof. The stays  87  can be comprise metal wires or polymeric members, having a suitable spring-like quality to urge the sleeve  89  to close, particularly under slight gastric pressure in the stomach  100 . The stays  87  can have a proximal end embedded within the mounting ring  3  to help hold the shape of the valve  21 , and also serve to inhibit inversion of the sleeve  89 .  
         [0031]    The valve  21  is normally closed, and the pressure differential between the stomach  100  and the esophagus  102 , and between the abdominal and thoracic cavities, act to maintain closure of the valve  21 . A suitable anti-reflux valve  21  for practicing the present invention is a typical mitral or bicuspid type valve of a half-flattened cylindrical shape. Such a shape is easily suspended from the mounting ring  13  by its cylindrical end. Other valves, such as sleeve valves, monocuspid valves, hinged disk valves and double hinged valves, are practicable in the present invention by the ordinarily skilled artisan.  
         [0032]    The bell-shaped upper end  83   a  and lower end  83   b  of the cylindrical housing  83  are used to advantage to engage the esophageal lumen  102  and the lining of the stomach  100  adjacent the gastroesophageal junction  104 , respectively. Such engagement aids the mounting ring  13  in securing the prosthesis  81  within the esophagus. However, one skilled in the art will recognize that the engagement of the lumen wall  102  of the esophagus by the housing  83  in the vicinity of the mounting ring  13  alone generally provides enough resistance such that the contribution of the bell-shaped lower end  83   b  is merely for an additional safeguard against the prosthesis  81  being inadvertently dislocated from the esophagus.  
         [0033]    A feature of this embodiment is the optional anti-inversion supports  85 , one end of which is fixed to the lower portion of the valve  21  and the other end of which is fixed to the wall of the lower end  83   b  of the cylindrical housing  83  . The supports  85  prevent the valve  21  from inverting. In the preferred embodiment shown in FIG. 1, the anti-inversion supports are biologically compatible ties affixed within the circumference of the interior wall of the cylindrical housing  83 .  
         [0034]    Referring to FIG. 4, the prosthesis  81  in this embodiment also includes a tissue anchor array  19  for fixing the prosthesis  81  to the lumen  100  of the esophagus. The tissue anchor array  19  extends radially outward away from the axis of the ring  13 . In this embodiment, the tissue anchor array  19  is comprised of barbed spikes  25  for piercing and engaging the lumen wall of the esophagus. The tissue anchor array  19  can be comprised of at least eight spikes or points  25 , but can have as many as forty or more spikes or points  25  arrayed in a plurality of rows. Each of the points  25  preferably has a laterally extending head  26  that can be fixed within the mounting ring  13 , for example, by casting or curing the ring  13  with the heads  26  embedded therein so that when cured, the material of the ring  13  completely covers the heads  26 . The points  25  are aligned to pass between the adjacent wires in the memory metal mesh of the upper end  83   a  of the housing  83 , and if desired, the memory metal mesh can also be embedded in the ring  13  material prior to curing or casting so that the ring  13  is securely fixed to the housing  83  .  
         [0035]    [0035]FIG. 5 illustrates another embodiment of the tissue anchor array  19 . In this embodiment, the tissue anchor array  19  is comprised of straight spikes  27 . The straight spikes  27  engage the lumen wall of the esophagus to secure the mounting ring  13  of the prosthesis  81 , but offer the advantage of easier removal than the barbed spikes  25  of the FIG. 4 embodiment. It may be desirable or necessary at times subsequent to insertion of the prosthesis  81  to remove the prosthesis  81  from the esophagus wall. Barbed spikes  25  cause heightened resistance to removal and act to tear the esophagus wall upon removal. Thus, the uniform spikes  27  of this embodiment can be advantageously used where removal of the prosthesis  81  can be more likely.  
         [0036]    It should be noted that in FIG. 5 the end points  29  of the wire mesh that forms the cylindrical housing  83  are affixed to the mounting ring  13  by being inserted in the mounting ring  13 . However, one skilled in the art will recognize that the end points  29  can be folded over the mounting ring  13 , they can be configured as shown in FIGS. 1 and 4- 5 , or they can be affixed to the mounting ring  13  by adhesives, etc. and remain within the purview of the invention.  
         [0037]    Yet another embodiment of the tissue anchor array  19  is illustrated in FIG. 6. In this embodiment, the tissue anchor array  19  is comprised of the end points  29  of the wire mesh that forms the cylindrical housing  83 . The end points  29  of the wire mesh are bent outward such that they are pointing outwardly from the surface of the mounting ring  13 . Sets of adjacent end points  29  can also be integrally wrapped together to form less flexible spikes that can penetrate the lumen wall without deformation (not shown). One skilled in the art will recognize that the end points  29  can similarly be reinforced at their tips to ensure that they can penetrate the lumen wall without deformation.  
         [0038]    [0038]FIG. 7 illustrates an embodiment of the valve prosthesis  81  having a tissue anchor array  30  adjacent to the bell-shaped lower end  83   b  of the cylindrical housing  83 . In this embodiment, the tissue anchor array  30  extends radially outward from the valve prosthesis  81 . The tissue anchor array  30 , in combination with the inherent anchoring features of the bell shapes, provides additional safeguard that the prosthesis  81  remains secure within the esophagus. In this embodiment, the tissue anchor array  30  is comprised of points or spikes  32  for piercing and engaging the esophageal junction  104 . The tissue anchor array  30  can be comprised of at least eight points or spikes  32 , but can have as many as forty or more points or spikes  32  arrayed in one or a plurality of rows.  
         [0039]    Referring to FIGS.  8 - 11 , in one preferred embodiment, the prosthesis system of the present invention includes an implantation tool  35  for holding and perorally inserting a prosthesis  81  down the lumen of a patient&#39;s esophagus to a position proximate the gastroesophageal junction, and fixing the prosthesis  81  to the lumen wall. The tool  35  comprises a flexible overtube  37 , of a construction and length suitable for peroral insertion into the esophagus. At one end, the overtube  37  has an integral compression collar  39  and at the other end a conventional handle (not shown) for manipulation. The compression collar  39  provides a means for releasably receiving the housing  83  of the prosthesis  81  in a compressed configuration. A hollow stylet  43  is slidably contained (or indwelling) in the length of the overtube  37  from end to end. At the collar  39  of the overtube  37 , the stylet  43  has a balloon  45  attached. The bladder of the balloon  45  communicates with the hollow (not shown) of the stylet  43 , and the balloon  45  is inflatable by pressurizing the hollow of the stylet  43  with a gas or liquid inserted into the hollow from the handle end of the tool  35 .  
         [0040]    It should be noted that because the cylindrical housing  83  of the prosthesis  81  is comprised of a memory material, depending upon the application environment, the balloon  45  within the overtube  37  may not be necessary for secure engagement of the mounting ring  31  to the esophagus. The prosthesis  81  can be secured within the esophagus by placing the compressed prosthesis  81  within the overtube  37 , positioning the overtube  37  within the esophagus, and releasing the prosthesis  81  from the overtube  37  in or near the gastroesophageal junction  104  . Once released, the cylindrical housing  83  springs back or is expanded by inflation of the balloon  45  to its initial form, thereby engaging the lumen wall  102  of the esophagus. The balloon  45  is then deflated for removal of the tool  35 .  
         [0041]    While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of preferred embodiments thereof. Many other variations are possible, which would be obvious to one skilled in the art. Accordingly, the scope of the invention should be determined by the scope of the appended claims and their equivalents, and not just by the illustrative embodiments.