Medical device for anastomosis

Abstract

A medical device for an anastomosis is provided. The medical device is distinguished by an inner tubular layer, an outer tubular layer, and a support element defining a longitudinal axis. It is further distinguished by two or more independent C-rings that are angularly distributed and positioned at an acute angle relative to the longitudinal axis of the support element at one end of the support element. The support element and the two or more C-rings are embedded between the inner tubular layer and the outer tubular layer. Envisaged application types are, for example, proximal anastomosis, distal anastomosis, or side-to-side anastomosis in a custom prefabricated graft. Embodiments of the invention can also be incorporated into anastomotic connector device designs. Embodiments of the invention can also be envisaged for vascular graft applications, such as coronary artery bypass grafts (CABG), dialysis access grafts, and peripheral vascular applications.

Description

Technical Field

[0001] The present invention relates to a medical device, and more particularly to a medical device for anastomosis. Background Art

[0002] Coronary artery bypass grafting (CABG) is a surgical procedure that restores blood flow in obstructed coronary arteries. When considering the proximal anastomosis of a CABG, the proximal portion of the graft needs to be trimmed at a nominally 45-degree angle and sutured to the perforation in the aorta. If a pure polymer tube is sutured at the proximal anastomosis, problems such as tip flattening and / or heel buckling / ovalization / kinking may occur. If an incorporated support element (e.g., a strain relief system (SRS)) is used as part of the anastomosis, the support element must be trimmed, which can result in "tip flattening" and thus create a compromised flow pattern at the inlet. Alternatively, metal struts incorporated into the anastomosis may pose a risk of sharp edge irritation or debris migration, which may lead to side effects such as inflammatory reactions or intimal hyperplasia. Other metal support element structures used in CABG devices, such as braided or knitted mesh, are easily loosened when trimmed for incorporation into the anastomosis. Therefore, there is a need in the art to design a new structure that overcomes at least some of these concerns or problems. Summary of the Invention

[0003] The present invention provides a medical device for an anastomosis. The medical device comprises an inner tubular layer, an outer tubular layer, and a support element defining a longitudinal axis. The device further comprises two or more independent C-rings disposed and positioned at one end of the support element at an acute orientation angle relative to the longitudinal axis of the support element. The support element and the two or more C-rings are embedded between the inner tubular layer and the outer tubular layer.

[0004] In one aspect of the present invention, the support element may also have an end ring attached to one end of the support element. The end ring is aligned more or less parallel, adjacent to, but independent of, the two or more C-rings.

[0005] In another aspect of the invention, the inner tubular layer and / or the outer tubular layer is an electrospun layer.

[0006] In yet another aspect of the present invention, the two or more C-rings are circular or oval in shape.

[0007] In yet another aspect of the present invention, the two or more C-rings are closed C-rings.

[0008] In yet another aspect of the present invention, the end ring is an oval closed end ring, an oval open end ring, a circular closed end ring, or a circular open end ring.

[0009] In yet another aspect of the invention, two or more C-rings are made of Nitinol.

[0010] In yet another aspect of the invention, the distance between the end ring attached to the support element and the first freestanding C-ring is nominally in the range of 0.5 to 1.5 mm.

[0011] In yet another aspect of the present invention, the distance between two adjacent C-rings in the two or more independent C-rings is nominally in the range of 1.5 to 2.5 mm.

[0012] In yet another aspect of the present invention, two or more C-rings are under preload.

[0013] In yet another aspect of the present invention, the acute orientation angle is 30-60 degrees or 15-90 degrees.

[0014] In another aspect of the invention, the support element is a stent, SRS, coil, wire, braid, or any other type of support structure used for cardiovascular implants.

[0015] The embodiments of the present invention have at least the following advantages.

[0016] • Separate loops allow the surgeon to trim to a desired trim length at the proximal and / or distal ends.

[0017] Cutting between the rings will avoid cutting through the metal.

[0018] • The shape of the rings and the spacing between two adjacent rings enable good kink resistance near the anastomosis.

[0019] • The openings in each individual ring allow the surgeon to cut the graft axially to enlarge the area of ​​the anastomosis (ie, create a "cobra head") to optimize flow through the anastomosis and reduce intimal hyperplasia, as well as better regulate intimal hyperplasia if it occurs.

[0020] In response to arterial pressure, the individual rings sutured to the anastomosis can and will gradually expand in the radial direction. This will help to reduce excessive shear stress at the anastomosis (and reduce intimal hyperplasia).

[0021] • Due to the rigid circular / oval shape of the ring and the rigidity of the metal at the tip of the anastomosis, buckling of the polymer is prevented and tip flattening is reduced.

[0022] • The C-ring, by virtue of its ability to open radially, allows the diameter of the graft ostium to be larger than the inner diameter of the graft body, thereby creating a funnel effect that optimizes blood flow for optimal chronic patency (at the anastomosis).

[0023] The number of rings used can be increased (using modular production tools, see Figure 4-5400 in ) to allow for a longer trimmable section if needed.

[0024] • The independent ring array has sufficient kink resistance for use in many anastomotic applications bypassing small diameter vessels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A medical device (cross-sectional view) is shown having two tubular layers (inner layer 110 , outer layer 120 ) embedded with a support element 130 and two or more independent C-rings 140 , according to an exemplary embodiment of the present invention.

[0026] Figure 2-3 A medical device is shown having a support element 130 with end rings 132 attached to the support element 130, according to an exemplary embodiment of the present invention. The support element end rings 132 are aligned more or less parallel to two or more separate C-rings 140.

[0027] Figure 4-5 A tool is shown that can assist in positioning and controlling the spacing of a C-ring relative to an implant, according to an exemplary embodiment of the present invention. A spacer wire 410 is used to overexpand the ring. After the wire is removed, the C-ring is deployed to its final position.

[0028] Figure 6 An angiogram is shown according to one embodiment of the present invention, wherein a C-ring is incorporated into the anastomosis. DETAILED DESCRIPTION

[0029] The present invention is a medical device incorporating a support element for anastomotic purposes. Examples of such support elements are stents, SRS, coils, wires, braids, or any other type of support structure typically used for cardiovascular implants. The medical device has two tubular layers (inner layer 110, outer layer 120) embedded in a support element 130, and two or more independent (separate) C-rings 140 near the ends of the support element. A C-ring is defined as a circular or elliptical ring that is not completely closed; that is, it has an opening large enough to accommodate standard surgical scissors for forming an axial slit without cutting through the annular struts. In one embodiment, the C-ring openings of the two or more independent C-rings are aligned with each other (see Figure 4-5 ). In an alternative embodiment, the C-ring may be a closed ring.

[0030] The longitudinal axis of the medical device is defined, and the medical device is then divided into: a (main) body section / portion 150, in which the support element is located; and a proximal end section / portion 160, adjacent to one end of the body section / portion, in which two or more independent C-rings 140 are positioned and distributed at an acute orientation angle relative to the longitudinal axis. Depending on the application scenario, the acute orientation angle can be 15-90 degrees, or preferably 30-60 degrees, or nominally 45 degrees.

[0031] The C-rings are embedded between the inner and outer tubular layers to prevent peeling of the layers. In one embodiment, the orientation angle is nominally approximately 45 degrees, which is consistent with the typical angle surgeons use to cut and trim medical devices for anastomosis procedures. In other words, the surgeon will cut the medical device between the two C-rings (i.e., the trimmable tips) because the outermost C-ring is preferably incorporated into the anastomosis. That is, if the suture is placed around the C-rings, by controlling the spacing between adjacent C-rings, tip flattening and / or heel buckling of the graft anastomosis can be eliminated / minimized.

[0032] In one embodiment, the support element 130 has an oval or circular end ring 132 attached to the support element (and parts thereof). This so-called end ring 132 is aligned more or less parallel to two or more independent C-rings 140.

[0033] In a preferred embodiment, the inner and outer tubular layers are electrospun layers, and the two or more oval C-rings are made of Nitinol.

[0034] The distance D1 between the end ring of the support element's body and the first C-ring is in the range of 0.5 mm to 1.5 mm or 0.5 mm to 2 mm, and is preferably about 1 mm. These exemplary spacings are a function of diameter and, in these examples, work well for a 4 mm inner diameter graft. For larger diameter grafts (i.e., thoracic grafts), they can reach 5 mm.

[0035] The distance D2 between two adjacent C-rings in the two or more C-rings is in the range of 1.5 mm to 2.5 mm or 1.5 mm to 3 mm, and is preferably about 2 mm. Similarly, as with D1, the spacing will be greater for D2 of larger implants.

[0036] This depends on the application, but for design purposes it is fair to consider that D1 is always smaller than D2, as it may be necessary to prevent the first free ring from wedging into the fixed ring.

[0037] In an exemplary embodiment, the C-rings are, by design, allowed to have a protrusion of approximately 45 degrees when assembled on, for example, a 4.5 mm diameter inner tubular layer. Thus, when considering assembly on a 4.7 mm inner tubular layer, this will result in the C-rings being "preloaded" due to the inner tubular layer pushing back on them. It should also be noted that the C-ring structure maintains its functionality, i.e., does not kink due to graft bending curvature as long as adjacent support elements incorporate rings of very similar orientation and similar geometry (e.g., strut width, thickness) at their proximal ends. The C-ring structure allows for radial expansion to conform to the size of the aortotomy, which ideally results in a funneling of the graft entrance, thereby improving hemodynamics. This phenomenon has been repeatedly observed in vivo during follow-up in chronic animal studies via angiography ( Figure 6 ).

[0038] In fact, there are only individually spaced C-rings at the ends, and no wires, so the surgeon does not have to cut the wires. In addition, the geometry of the C-rings eliminates "tip flattening" and heel buckling at the anastomosis because the ring-based support elements can effectively prevent radial deformation.

[0039] The C-ring can be laser cut from a metal tube or flat sheet, preferably nitinol. The profile of the C-ring should avoid sharp edges that could cause long-term abrasion with surrounding tissue and should therefore be smoothed (e.g., mechanically or electropolished). The opening of the C-ring should be wide enough to allow the end user to cut a slit through the ring in the axial direction as a common vascular surgical technique without actually cutting the C-ring.

[0040] The medical device can be made by electrospinning an inner tubular layer 110 onto a metal rod (not shown). The support element 130 can then be placed on the inner tubular electrospun layer 110. The C-ring 140 can then be deployed on top of the inner layer 110 at a controlled location to ensure the correct distance and orientation to the edge of the body 150 of the implant 130. Preferably, a dedicated tool 400 (see FIG. 4 ) can be used for the deployment of the C-ring. Figure 4-5 ). Tool 400 should allow for widening the profile of C-ring 140 beyond the circumference of the tubular layer and for the ring to be stably released into its final position against the tubular inner layer. Arm 410 may be integrated with tool 400 to control the opening of C-ring 140. Finally, the outer tubular layer 120 is electrospun to cover the support element 130 and C-ring 140, thereby providing a smooth connection of the electrospun fibers of the inner and outer layers to form a single electrospun tubular assembly.

[0041] The electrospun materials mentioned in this document can include a urea-pyrimidinone (UPy) quadruple hydrogen bonding motif (initiated by Sijbesma (1997), Science 278, 1601-1604) and a polymer backbone, for example, selected from the group consisting of biodegradable polyesters, polyurethanes, polycarbonates, poly(orthoesters), polyphosphates, polyanhydrides, polyphosphazenes, polyhydroxyalkanoates, polyvinyl alcohol, polypropylene fumarate. Examples of polyesters are polycaprolactone, poly(L-lactide), poly(DL-lactide), poly(valerolactone), polyglycolide, polydioxanone, and copolyesters thereof. Examples of polycarbonates are poly(trimethylene carbonate), poly(dimethylene trimethylene carbonate), and poly(hexamethylene carbonate).

[0042] Alternative non-supramolecular polymers can achieve the same results if the properties of the materials are carefully selected and the materials are processed to ensure the desired surface properties. These polymers can include biodegradable or non-biodegradable polyesters, polyurethanes, polycarbonates, poly(orthoesters), polyphosphates, polyanhydrides, polyphosphazenes, polyhydroxyalkanoates, polyvinyl alcohol, and polypropylene fumarate. Examples of polyesters are polycaprolactone, poly(L-lactide), poly(DL-lactide), poly(valerolactone), polyglycolide, polydioxanone, and their copolyesters. Examples of polycarbonates are poly(trimethylene carbonate), poly(dimethylene trimethylene carbonate), and poly(hexamethylene carbonate).

[0043] Application Examples

[0044] The types of applications that can be envisioned are, for example, proximal anastomosis, distal anastomosis, or side-to-side anastomosis in custom prefabricated grafts. Embodiments of the present invention can also be incorporated into anastomotic connector device designs. Embodiments of the present invention can also be envisioned for (small-caliber) vascular graft applications such as CABG, dialysis access grafts, and peripheral vascular applications, including but not limited to critical limb ischemia, Fem-Pop grafts, or BTK grafts.

Claims

1. A medical device for anastomosis, comprising: (a) Inner tubular layer; (b) outer tubular layer; (c) a support element, the support element defining a longitudinal axis; as well as (d) two or more independent split C-rings distributed and positioned at an acute orientation angle relative to the longitudinal axis of the support element at one end of the support element, and the two or more independent split C-rings are parallel to each other; wherein the support element and two or more open C-rings are embedded between the inner tubular layer and the outer tubular layer, wherein the support element further comprises a closed end ring attached to the one end of the support element, wherein the end ring is aligned substantially parallel to, adjacent to, but independent of, the two or more open C-rings, wherein an outermost split C-ring is incorporated into the anastomosis, and wherein the two or more split C-ring openings are aligned with one another.

2. The medical device according to claim 1, wherein The inner tubular layer is an electrospun layer.

3. The medical device according to claim 1, wherein The outer tubular layer is an electrospun layer.

4. The medical device according to claim 1, wherein The two or more open C-rings are circular or oval.

5. The medical device according to claim 1, wherein The two or more C-rings are made of Nitinol.

6. The medical device according to claim 1, wherein The distance between the end ring attached to the support element and the first separate C-ring is nominally in the range of 0.5 to 1.5 mm.

7. The medical device according to claim 1, wherein The distance between two adjacent C-rings in two or more separate split C-rings is nominally in the range of 1.5 to 2.5 mm.

8. The medical device according to claim 1, wherein The acute orientation angle is 30-60 degrees.

9. The medical device according to claim 1, wherein The acute orientation angle is 15-90 degrees.

10. The medical device according to claim 1, wherein The support element is an SRS, a wire or any other type of support structure used for cardiovascular implants.

11. The medical device according to claim 1, wherein The support element is a coil or a braid.

12. The medical device according to claim 1, wherein The two or more C-rings are under preload.

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