News Column

Patent Issued for Implantable Graft to Close a Fistula

July 15, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Armstrong, David N. (Atlanta, GA), filed on May 30, 2007, was published online on July 1, 2014.

The patent's assignee for patent number 8764791 is Cook Medical Technologies LLC (Bloomington, IN).

News editors obtained the following quote from the background information supplied by the inventors: "Fistulae occur commonly in man. Such fistulae may be congenital or may be caused by infection, inflammatory bowel disease (Crohn's disease), irradiation, trauma, childbirth, or surgery, for example.

"Some fistulae occur between the vagina and the bladder (vesico-vaginal fistulae) or between the vagina and the urethra (urethro-vaginal fistulae). These fistulae may be caused by trauma during childbirth. Traditional surgery for these types of fistulae is complex and not very successful.

"Other fistulae include, but are not limited to, tracheo-esophageal fistulae, gastro-cutaneous fistulae, and anorectal fistulae. For example, anorectal fistulae may occur between the anorectum and vagina (recto-vaginal fistulae), between the anorectum and bladder (recto-vesical fistulae), between the anorectum and urethra (recto-urethral fistulae), or between the anorectum and prostate (recto-prostatic fistulae). Anorectal fistulae may result from infection in the anal glands, which are located around the circumference of the distal anal canal forming an anatomic landmark known as the dentate line 1, shown in FIGS. 1 and 2. Approximately 20-39 such glands are found in man. Infection in an anal gland may result in an abscess, which then tracks through or around the sphincter muscles into the perianal region, where it drains either spontaneously or surgically. The resulting tract is known as a fistula. The inner opening of the fistula, usually located at the dentate line, is known as the primary opening 2. The outer (external) opening, located in the perianal skin, is known as the secondary opening 3.

"FIGS. 1 and 2 show examples of the various paths that an anorectal fistula may take. These paths vary in complexity. Fistulae that take a straight line path from the primary opening 2 to the secondary opening 3 are known as simple fistulae 4. Fistula that contain multiple tracts ramifying from the primary opening 2 and have multiple secondary openings 3 are known as complex fistulae 5.

"The anatomic path that an anorectal fistula takes is classified according to its relationship to the anal sphincter muscles 6, 7. The anal sphincter includes two concentric bands of muscle--the inner, or internal, sphincter 6 and the outer, or external, anal sphincter 7. Fistulae which pass between the two concentric anal sphincters are known as inter-sphincteric fistulae 8. Those which pass through both internal 6 and external 7 sphincters are known as trans-sphincteric fistulae 9, and those which pass above both sphincters are called supra-sphincteric fistulae 10. Fistulae resulting from Crohn's disease usually ignore these anatomic paths, and are known as extra-anatomic fistulae.

"Many complex fistulae contain multiple tracts, some blind-ending 11 and others leading to multiple secondary openings 3. One of the most common and complex types of fistulae are known as horseshoe fistulae 12, as illustrated in FIG. 2. In this instance, the infection starts in the anal gland (the primary opening 2) and two fistulae pass circumferentially around the anal canal, forming a characteristic horseshoe configuration 12.

"Surgical treatment of fistulae traditionally involves passing a fistula probe through the tract, in a blind manner, using only tactile sensation and experience to guide the probe. Having passed the probe through the fistula tract, the overlying tissue is surgically divided. This is known as a surgical fistulotomy. Because a variable amount of sphincter muscle is divided during the procedure, fistulotomy may result in impaired sphincter control or even incontinence.

"Alternatively, the fistula tract may be surgically drained by inserting a narrow diameter rubber drain, known as a seton, through the tract. After the seton is passed through the fistula tract, it may be tied as a loop around the contained tissue and left for several weeks or months. This procedure is usually performed to drain infection from the area and to mature the fistula tract prior to a definitive closure or sealing procedure.

"More recently, methods have evolved to inject sclerosant or sealant (collagen or fibrin glue) into the tract of the fistula. Such sealants are described in Rhee, U.S. Pat. No. 5,752,974, for example. The main drawback with these methods is that the glues have a liquid consistency and tend to run out of the fistula tract once the patient becomes ambulatory. In addition, failure rates of these methods are high (up to 86% failure). See Buchanan et al., Efficacy of Fibrin Sealant in the Management of Complex Anal Fistula, DIS COLON AND RECTUM Vol. 46, No. 9, 46:1167-1174 (September 2003). Usually, multiple injections of glue are required to close the fistula. In some instances, closure of a fistula using a sealant may be performed as a two-stage procedure, comprising a first-stage seton placement, followed by injection of the fibrin glue several weeks later. This procedure reduces residual infection and allows the fistula tract to 'mature' prior to injecting a sealant. Injecting sealant or sclerosant into an unprepared or infected fistula as a one-stage procedure may cause a flare-up of the infection and even further abscess formation. Alternative methods and instruments, such as coring-out instruments (See, e.g., U.S. Pat. Nos. 5,628,762 and 5,643,305), simply make the fistula wider and more difficult to close.

"An additional means of closing the primary opening is by surgically creating a flap of skin, which is drawn across the opening and sutured in place. This procedure (the endo-anal flap procedure) closes the primary opening, but is technically difficult to perform, is painful for the patient, and is associated with a high fistula recurrence rate.

"An important step in successful closure of a fistula is accurate identification and closure of the primary opening. An accurate means of identifying the primary opening involves endoscopic visualization of the fistula tract (fistuloscopy), as disclosed in co-pending application Ser. No. 10/945,634 (Armstrong). Once the primary opening has been accurately identified, effective closure is necessary to prevent recurrence. The current invention comprises a graft that may be used to effectively plug or occlude the primary opening of the fistula tract."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "One object of the present invention is to provide a new technique of minimally invasive fistula closure. Another object is to provide a technique that obviates the need for surgical fistulotomy and avoids surgical pain and the attendant complications of the procedure. Still another object of the invention is to provide an accurate and complete closure of a fistula, thereby preventing a recurrent or persistent fistula. Yet another object of the present invention is to provide a technique that involves no cutting of tissue, sphincter damage, or incontinence.

"The present invention may be used in any type of fistula. For example, the claimed devices and methods may be used to plug or occlude tracheo-esophageal fistulae, gastro-cutaneous fistulae, anorectal fistulae, fistulae occurring between the vagina and the urethra or bladder, or fistulae occurring between any other two portions of the body.

"In one embodiment of the present invention, a biocompatible graft having a curved, generally conical shape is provided. The graft may be used to plug, or occlude the primary opening of the fistula. Desirably, the graft is approximately 5 to 10 centimeters (2 to 4 inches) long and tapers continuously from a thicker, 'trumpet-like' head to a thin filamentous tail. Desirably, the diameter of the head is approximately 5 to 10 millimeters and tapers to a diameter of 1 to 2 millimeters at its tail.

"The graft of the present invention may be made of any suitable biological or synthetic materials. Desirably, the head and the tail are one continuous piece made of the same material. Suitable biological materials include, but are not limited to, cadaveric allografts from human donors or heterografts from animal tissues. Suitable synthetic materials include, but are not limited to, polygalactin, polydioxanone and polyglycolic acid. Desirably, the biological and/or synthetic material used in the graft of the present invention elicits little immunological reaction, has some inherent resistance to infection, and promotes tissue reconstruction (rather than complete absorption of the graft into the surrounding tissue), thereby occluding the fistula.

"The graft of the present invention may be pulled into the fistula, tail first, through the primary opening, toward the secondary opening. In one embodiment, the graft is drawn into the fistula and the trumpet-like head end of the graft is gradually 'wedged' into the primary opening in a manner similar to that of inserting a plug in a hole. The head and/or tail may be further secured by sutures or other suitable means, which may be formed as an integral part of the graft. A trumpet-like head allows the graft to be used for any diameter of primary opening. By applying adequate force to the graft during its insertion, the head of the graft fits snugly into the primary opening and conforms to the size of the primary opening. Multiple or composite grafts may be used for multiple or complex fistulae.

"Additional features and advantages of the present invention will be apparent to one of ordinary skill in the art from the drawings and detailed description of the preferred embodiments below."

For additional information on this patent, see: Armstrong, David N.. Implantable Graft to Close a Fistula. U.S. Patent Number 8764791, filed May 30, 2007, and published online on July 1, 2014. Patent URL:

Keywords for this news article include: Technology.

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Source: Journal of Technology

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