Implantable Stent

Abstract

The invention is a stent designed for indwelling in a body, where its purpose would be to assist in the drainage of liquid from one part of the body to another. The stent is composed of a material that would typically be coiled to form a cylindrical shape along the length of the stent. Each end of the stent would typically be shaped to form a looped pigtail to prevent migration in the vessel. The stent can be used for minimally invasive procedures or alternatively, it could be placed percutaneously. This stent could be used in various parts of the body, such as the ureter, urethra, bile duct, liver, pancreas, vascular system and neurovascular system.

Claims

1. A thick-walled stent, as defined by having a radius of less than ten times its wall thickness, capable of being inserted into a patient comprising a wire or a plurality of wires formed into a helix with closely connecting coils, having a distal and proximal end and an internal lumen, wherein said helix is shaped into a pigtail or a partial loop or a single loop or a plurality of loops at either the proximal end or the distal end or both the proximal and distal ends of said helix wherein said pigtail, partial loop, a single loop or plurality of loops prevent the migration of the stent from the location said stent is implanted in a patient, and further wherein the proximal end of said stent is not longitudinally connected to the distal end of said stent.

2. The stent of claim 1, with an atraumatic tip on either the proximal end or the distal end or both or wherein said wires are hollow or wherein the proximal ends or the distal ends or both the proximal and distal ends of the wires forming the helix ending in an anti-migration pigtail, partial loop, a single loop or a plurality of loops are braided or plated or welded together or attached to another anti-migration feature or wherein said helix is comprised of one or more plurality of coiled wires consecutive coils used to form the helix touch each other or wherein said stent is coated or plated with silver or gold metal, a radiopaque material, an anti-bacterial coating, a drug, a polymer coating or is inserted into a tube or any combination thereof or wherein the plurality of wires coiled together to form the helix of the stent transitions to an uncoiled section and that said uncoiled section further is covered with a tube or is uncovered and is reinforced with a mandrel or a cannula or is not reinforced or wherein said wires are solid wires or wherein said stent is covered by a polymer coating or is inserted in a tube or wherein said hollow wires, plastic coating or outer tube may further have a plurality of holes throughout the surface of said wires, coating or outer tube or wherein said stent is used to treat a urological condition or wherein said tube is manufactured from a tube or metallic tube or a hypotube used to treat bodily vessel obstructions, said stent being formed by a laser cutting said tube, metallic tube or hypotube into a helix.

3. The stent of claim 1, further comprising a wire or rod or a plurality of wires or rods attached to the outer or inner surface of the helix of coiled wire or coiled wires or further comprising a spiral cup shape, circular disc shape or cup shape on top of an inverted cup shape formation at one or both ends.

4. The stent of claim 1 incorporated in a stent kit composed of an outer sheath, a stent inserter or a guide wire, a stent loading tube, ancillary parts and the stent according to claim 1.

5. The stent kit according to claim 4, wherein the outer sheath comprises a tube having a proximal and distal end and an inner lumen extending throughout the entire length of said tube wherein when the stent is inserted into the proximal end of the lumen of said tube said stent is pushed along the length of the tube by the stent inserter and the guide wire of claim 4 or wherein the outer sheath further comprises one or more radiopaque markers at the distal end of the sheath or wherein the outer sheath is coated with a hydrophilic coating or wherein the stent inserter is comprised of a single material or a composition of materials, or braided or coiled materials provided said stent inserter has a compressive strength greater than 50 kPa or wherein the stent inserter further comprises markings on indicating the length of the stent inserter from the distal end to the proximal end of the stent inserter, wherein when the stent is inserted into the patient, said markings indicate to the practitioner inserting the stent, the position of the stent in the patient's body as it is being inserted into the patient or wherein the distal end of the stent inserter is atraumatic or radiopaque or has radiopaque marker bands or wherein the stent inserter is surrounded by a tube that can be detachable or not detachable or where any surface of the inserter or sheath is coated with a lubricious coating or a hydrophilic coating or wherein the stent is inserted into the patient by pulling back the sheath with the stent inserter held in position until the sheath is pulled back and the proximal end of the stent is fully deployed, at which point the sheath is in line with the inserter and both sheath and inserter can be withdrawn from the body in conjunction with each other or separately or wherein the guide wire is an over-the-wire system, a long-wire system, a short-wire system or a wire system through a side port.

6. A method of placing a metallic stent in the ureter using a metallic hypotube as a delivery device, said hypotube comprising a metal tube with a lumen or a number of lumens and having a plurality of openings cut through or cut onto the tube surface to increase flexibility and said stent being pushed from the proximal end of the hypotube to the distal end of the hypotube for delivery within a body lumen of a patient, whereby the hypotube provides pushability and radial strength in narrow ureters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1a is an illustration of prior art and FIG. 1b is an illustration of prior art;

[0050] FIG. 2 is an illustration of the inserter;

[0051] FIG. 3a is a cross-sectional view of the stent inserter with the mandrel placed inside it;

[0052] FIG. 3b is a cross-sectional view of the stent inserter without any mandrel inside it;

[0053] FIG. 4 is an illustration of the outer sheath;

[0054] FIG. 5 is an illustration of the radiopaque tip of the sheath and the stent inserter;

[0055] FIG. 6 is an illustration of the sheath with the stent inserter inside it;

[0056] FIG. 7 is an illustration of the cross-sectional view of the sheath;

[0057] FIG. 8 is an illustration of the markings on the proximal end of the inserter;

[0058] FIG. 9 is an illustration of a coiled pig-tailed stent;

[0059] FIG. 10 is an illustration of a longitudinal section of the coiled stent;

[0060] FIG. 11 is an illustration of a coiled stent with a pig-tail on one end only;

[0061] FIG. 12 is an illustration of a cross-sectional view of the stent;

DETAILED DESCRIPTION OF THE INVENTION

[0062] One embodiment of the present invention is a kit for placing a stent. This kit will typically include an outer sheath, stent inserter, stent and a stent holder. The sheath and inserter are designed to be used in combination according to user requirements and are used solely for placement of the indwelling stent and removed after this has been achieved.

[0063] The stent in this embodiment is typically made from metal wires which have been coiled over a mandrel to create a cylindrical shaped part possessing an internal lumen, which makes up the body of the stent. The ends of the stent would typically be formed into a loop or a pigtail at the distal and proximal ends. The wire of the stent will typically be terminated by laser welding the wire into the end or by welding the wire beneath a ball or similar object to create an atraumatic surface.

[0064] There are numerous possible embodiments associated with the stent kit and stent design for the invention described herein and these are detailed in the claims below. All drawings, summaries, descriptions, embodiments and objects are intended to be illustrative rather than limiting.

Embodiments

[0065] FIG. 1A shows prior art of ureteral stents 34. FIG. 1B shows the function of ureteral stents. Typically, these stents are placed in a minimally invasive manner by passing the stent over a guide wire that has been positioned in the renal pelvis of the kidney. A pusher is used to advance the stent along the wire from the urethra to the bladder and subsequently into the ureter. Other methods for stent placement are percutaneously where the physician accesses the ureter through the skin of patient using nephrostomy methods.

[0066] FIG. 2 displays the stent inserter and outer sheath. An embodiment of the design detailed in FIG. 2 shows the small diameter of the outer sheath. The stent inserter reference number in FIG. 2 is 10. This significantly reduces trauma to the patient during the procedure and is specifically suitable for patients with ureters that are sized in the range from 0.3 mm to 0.7 mm (0.011-0.027). Other physician benefits are the highly radiopaque properties of the stent and the inserter tip allowing the physician to place the device without the need for a guide wire. This would be a benefit during paediatric or small animal veterinary procedures where it is important to keep fluoroscopic exposure to a minimum.

[0067] A sheath incorporating one embodiment of the invention is generally indicated by the reference number 16 in FIG. 4.

[0068] Materials most suitable for the outer sheath might be stainless steel, PTFE, FEP, fluoropolymer, silicone, polyurethane, polyethylene, PEBAX and nylon, but any material approved for use in medical devices can be used. The sheath would typically be flared at the proximal end. The flared end can be attached to the connector cap or handle by gluing or by over-moulding or by welding the proximal end on to a connector cap or handle 17 (FIG. 4). The connector cap could have a male ending to enable it to attach to or detach from the female luer 33 (FIG. 6) of the inserter. The distal end has a radiopaque marker as seen in FIG. 5, reference number 19. The radiopaque marker would typically be a marker band, a radiopaque filler encompassed in the plastic of the sheath or radiopaque ink. The dimensions of the sheath would typically be 15 cm to 60 cm in length 18 (FIG. 4) and typically 0.011 to 0.090 in diameter 20 (FIG. 7).

[0069] The inserter 10 (FIG. 2) can consist of a metal or a plastic polymer material such as, but not restricted to PVC, polyurethane, polyethylene, silicone, FEP, PEBAX, polyamide, polyimide and PEEK. Alternatively, the stent inserter can be a combination of a polymer tube surrounding a metal cannula or mandrel (FIG. 3a). The dimensions of the inserter 10 would typically be 15 cm to 60 cm in length and typically 0.007-0.090 in diameter 15 (FIG. 3a & FIG. 3b). The stent inserter could have markings 21 (FIG. 8) on its length 12 (FIG. 2) to denote distance of the distal end of the inserter within the outer sheath and/or to give indication of the stent and/or inserter position during the procedure.

[0070] If the inserter was to be made of a cannula or mandrel surrounded by a polymer tube, the metal part may be the same length as the polymer tube 13 or it could be shorter than the tube to allow for a polymer atraumatic tip. Alternatively, the metal inserter could be shaped to form an atraumatic tip. The metal inner section may also be ground or electro-polished to taper at the distal end to create an atraumatic tip 14 (FIG. 5).

[0071] For successful placement of the inserter tip in the renal pelvis of the kidney, it is essential that the distal tip of the inserter is highly radiopaque 14. This can be achieved by: incorporating a radiopaque filler in the distal section of the polymer inserter; a radiopaque metal maker band; radiopaque ink; metal plating with a radiopaque metal; or a radiopaque polymer strip embedded in the distal tip during processing. The metal part of the inserter can be attached to the outer inserter tube via a luer and a connector cap 11. The polymer end of the inserter would typically be flared with a female luer end to allow the physician to attach or detach it from the outer sheath.

[0072] An embodiment of the design detailed in FIG. 9 is a coiled stent 22. The stent can be produced by coiling a metal wire such as stainless steel, nitinol, MP35N or MP159 or by using a mix of metal and a polymer. The coil pattern can be any hilar pattern or a variety of hilar patterns 28 (FIG. 10).

[0073] Pressure generated in the kidney and ureter would force urine in through the coils 29 (FIG. 10) of the stent and it could drain into the bladder through the coils in the proximal end of the stent.

[0074] The stent would typically have a looped pigtail 23 on both the distal and proximal ends to prevent migration of the stent from its position in the ureter. The loops would be created by heat-forming the metal used in the stent. The diameter 25 of the loop/pigtail can be in the range of 3-16 mm.

[0075] It is also possible for the stent to have a straight body and only transition into a loop or pigtail on one end 31 (FIG. 11). The stent can also be produced by a braided mesh and with polymer covering/membrane over the mesh.

[0076] Other additions to the stent design could consist of a polymer coating or membrane over the stent. Holes could be created in the membrane of the stent to allow urine to flow into or out of the stent, according to the pressure exerted. The holes could be created by perforating the membrane with a sharp tool or by laser.

[0077] The wire used to create the stent would typically range in size from 0.0005 to 0.040 30 (FIG. 10).

[0078] The wire can be any produced in various shapes. The diameter of the stent would typically be from 0.3 Fr to 5.0 Fr, as seen at reference 32 (FIG. 12). The length of the stent would typically range from 3 cm to 20 cm, as seen at reference 26 (FIG. 9).

[0079] Alternatively, the stent could be created by laser cutting a hollow tube and forming it into the required shape. The laser cutting could begin with a hypotube, HHS, mandrel or cannula to form the required shape. The thickness of the metal tube used to create the stent could range from 0.0005 to 0.040. The laser could cut out a single design iteration or a variety of designs.

[0080] The tip of the stent 24 (FIG. 9) could be created by soldering or laser welding the end of the wire into the end of stent or by welding a radiopaque dome-shaped cap or ball on the ends of the stent or by welding on a plastic or polymer tip. The intention regarding the tip 24 is that it would be atraumatic to the body of the patient and biocompatible. The stent can be plated with a metallic material, such as gold, to enhance its radiopaque properties, prevent encrustation and to provide a smooth surface, onto which bacteria cannot easily adhere. Other forms of finishing would include passivation, mechanical polishing, etching, slurry cleaning the internal diameter and electro-polishing. Anti-bacterial or anti-encrustation coating may also be applied to the stent's surface 27 (FIG. 10) to prevent or reduce encrustation of the stent for its indwell duration.