The present invention relates generally to devices for connecting the ends of interrupted blood vessels, urethras or other tubular organs and, more particularly, to a stent that is secured in place within adjacent ends of two interrupted blood vessels, urethras or other tubular organs to establish flow therethrough.
Vascular and microvascular surgery entails the connection of the ends of various sizes and types of interrupted blood vessels. In all cases, it is essential to obtain a secure and leak-free connection between the blood vessel ends.
Currently, both vascular and microvascular surgery utilize extremely technically-demanding processes of hand sewing vessel ends to suture them together. Often, in order to insure successful outcomes, this must be done under loupe or microscopic magnification using delicate suturing techniques requiring great skill and experience on the part of the surgeon. Furthermore, despite surgeons' best efforts and initially successful suturing, the resulting anastomotic site is subject to thrombosis which may adversely impact patient outcomes. There is also the danger that the stitches will cut through a vessel which can produce leakage and failure of the suture. Other drawbacks in connection with the use of hand sewing are the slow and tedious process that it entails which often makes for operations of long duration, and the possible presence of suture material in the lumen of the vessel which may interfere with blood flow or form a nidus for thrombus formation. Additionally, the time required for performing such painstaking microsurgery is significant and increased ischemia time during which time the vessels are not connected puts local tissue—and ultimately the patient—at risk.
There is currently no widely accepted stitchless device or technique for simply and reliably joining arteries end-to-end. Known devices for coupling veins end-to-end without stitching typically involve affixation of separate collar-like members to each of the vessel ends and joinder of these members. However, the transposition of these vein couplers to arteries is difficult because the arterial wall thickness is greater than that of veins. This prevents the proper folding of the artery necessary for proper execution of the coupling device. Also, the collars interfere with or prevent direct contact between the two vessel ends. Additionally, the affixation and joinder techniques currently in use with vein couplers are generally cumbersome and technically difficult to use.
Also, it is often necessary to attach blood vessels of different diameters end-to-end. This mismatch of vessel diameters can create mechanical problems at the anastomotic site that predisposes the site to flow irregularities and thrombosis. Current coupling devices do not optimally address significant vessel mismatches.
In view of the limitations and shortcomings of current hand sewn suturing techniques and stitchless vein attachment devices, it would be highly desirable to provide a simple, reliable device and method that can be used to join both veins or thicker walled arteries end-to-end, quickly, efficiently, securely, and without danger of damaging vessel walls, inducing thromboses, or causing other complications. If a range of different vessel diameters could be accommodated by a single device and method, this would be a further important contribution to the art. If the device and method made possible quick vascular diameter matching and alignment, minimized anastomotic leakage and kinking, and facilitated blood flow at the anastomosis site to minimize the chance of clotting, an important advance in the art of joining blood vessels end-to-end would be at hand. The present invention embodies a device and method that provides all of these properties and advantages. The present invention also provides like properties and advantages when used to join other tubular organs like urethras.
Further advantages and characteristics of the present invention will become apparent to those skilled in the art from the detailed description that follows and the accompanying drawings. Preferred but nonexclusive embodiments of the invention are illustrated and discussed by way of non-limiting examples of the invention.
The present invention may be used wherever two blood vessels or other tubular organs like urethras must be connected in an end-to-end fashion. Common applications include, for example, attachment of blood vessels for organ transplantation, free tissue transfers, or various forms of cardiovascular bypass surgery, as well as urethral anastomoses. The invention is able to accommodate a range of vessel and organ sizes in these and other applications.
The present invention thus consists of stents for connecting two blood vessels or other tubular organs in end-to-end fashion to enable flow therethrough. The invention also includes methods of using such a device in achieving anastomoses of blood vessels or other tubular organs.
The stent includes a central portion, inlet and outlet nipples at opposite ends of the central portion and a lumen passing through the central portion and the nipples. The central portion preferably will be enlarged relative to the nipples to facilitate flow through the stent. Indeed, it is preferred that such an enlarged central portion will have a maximum cross-section between about 125 to 200% of the diameter of the openings of the nipples. Also, the stent preferably will have an outer surface configured so that the transition from the outer surface of the nipples to the outer surface of the central expanded portion is gently sloped.
The contours of the lumen in one embodiment will generally follow the contours of the outer surface of the stent. In embodiments in which the stent has an expanded central portion, the stent wall may be thickened in the area of the expanded portion to reduce the cross-section of the lumen in that area to varying degrees up to and including to such an extent that the inner wall will be flat and the lumen through the stent will be of a uniform tubular shape.
The stent may be made of a solid material or it may be made of a porous mesh. Preferably, the outer surface of the stent will be coated with a tissue ingrowth material. In order to improve the purchase between the stent and the interior of the portions of the vessels that will overlie the stent, the outer surface may also have one or more of a raised netting surface, hooks, serrations, barbs, ribs or a surface configured for ingrowth from the vessels attached to the stent.
The invention also entails a method of joining the ends of two blood vessels (or other tubular vessels) using a stent as discussed above. In practicing the method, the nipples of the stent will be inserted within the lumens of the vessels and the vessels will be clamped to the stent. In stents having a solid wall, one or both of the vessels may be drawn only partially up the outer wall of the nipples and then clamped or the vessels may be drawn up to approximately the midpoint of the stent so that their edges meet. When the stent is in the form of an open mesh, the blood vessels must be drawn up over the entirety of the stent to prevent leakage therethrough. Finally, clamps will be applied as needed either at the nipples and/or at locations on the central portion of the stent. In one embodiment, the two vessels be drawn up along the outer surface of the stent until the vessel ends meet and a clamp applied over the interface between the adjoining vessel ends to both attach the vessels to the stent and to seal the interface between the adjoining vessel ends.
Preferred embodiments of the invention are described with reference to the accompanying drawings, in which like elements bear like reference numerals, and wherein:
The following detailed descriptions and accompanying drawings are provided for the purpose of illustrating and describing certain presently preferred embodiments of the invention. These descriptions and drawings are not intended to limit the scope of the protection of the invention in any way.
Turning to
A lumen 18 passes through the central expanded portion and the nipples of the stent from a first generally annular nipple opening 20 in end 22 of the stent through the center expanded portion 12 to a second opening 24 at end 26. Ends 22 and 26 may be chamfered as shown at 27 to facilitate entry of the nipple into the vessel lumens. The leading edge of the nipple, however, should be rounded to minimize the danger of damaging the vessel as it moves along the nipple lumen. The walls 28 of the stent are generally of uniform thickness so that the contours of lumen 18 generally follow the contours of the outer surface 30 of the stent. Also, the surface 25 of lumen 18 preferably is smooth in order to maximize laminar flow and minimize the danger of clot formation. Indeed, to facilitate blood flow and further minimize the danger of clot formation, the surface of the lumen may be coated with anti-thrombogenic materials including endothelial cells, fibrous coatings, or other compositions. The coating compositions can be growth and differentiation modulators, such as but not limited to, TGF-β and/or bone morphogenic protein(s) (BMPs), bFGF, IGF-1, IGF-II, and anticoagulants, such as but not limited to, streptokinase, urokinase (uPA), and IPA, or ascorbic acid.
As seen in
The stent may be formed from an appropriate metal such as stainless steel, or from a shape memory alloy like Nitinol. If made of metal, the stent can be laser-machined or it can be mechanically expanded in the center portion. The stent may have a solid wall or it may be made of a porous mesh. Also, the outer surface of the stent may be coated with a membrane of porous ePTFE or another polymer to promote tissue ingrowth to help prevent leaking.
In an alternative embodiment, the stent may be formed from a polymer. In a preferred embodiment the polymer may be selected from the group consisting of shape memory polymers, silicone, polyurethane, polyethylene, acrylonitrile butadiene stryrene (ABS), polycarbonate, polypropylene, styrene, polyamide (nylon), polymide, PEEK, PEBAX, polyester, PVC, fluropolymers (TEFLON), and co-polymers.
In another embodiment of the invention as illustrated in
In yet another embodiment of the invention illustrated in
As noted above, in the stent 10 of
In order to join vessels by way of the stent of the invention, clamps will generally be placed over portions of the vessels overlying the stent. Any appropriate spring clip, cable clamp, hose clamp design, or band. For example, adjustable cable tie 82, spring clip 84, or cable clamp 86 of
The following examples illustrate modes of practicing the method of the invention but should not be construed as in any way limiting its scope. A stent in accordance with the present invention thus may be used as illustrated in
Also, it should be appreciated that when the stent has porous mesh walls, the entire stent must be covered with the clamped-in-place vessel ends. However, when the stent has solid walls, one or both of the vessels need not be drawn up to the midpoint of the enlarged center portion but rather may be clamped in place with its end at a desired position on stent nipple.
The procedure of Example 1 is followed except that vessels with different diameter lumens are joined using the stent of
The procedure of Example 1 is followed except that vessels with different diameter lumens are joined using the stent of
In this example, the outer surfaces of the stents are configured as in one of
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.
This patent application claims the benefit of U.S. Provisional Patent Application No. 60/797,946, filed May 5, 2006.
Number | Date | Country | |
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60797946 | May 2006 | US |