Curved ureteric access sheath

Abstract

The invention provides a ureteral access sheath (UAS) (10). The UAS includes a resiliently deformable tube (12) provided with shape memory, which shape includes a rounded bend (14) at its leading end which corresponds to the anatomical shape of a ureter's entry up to and past the junction into the renal cavity (renal pelvis) and an access funnel (16) at the trailing end of the tube (12). The UAS (10) further includes a corresponding dilator (18), which dilator (18) is provided with a tubular body (20) with shape memory, which shape includes a rounded bend (22) at its leading end to generally correspond to the bend shape (14) of the resiliently deformable tube (12) of the UAS (10).

Description

[0001] Title: CURVED URETERIC ACCESS SHEATH

[0002] Technical field of the invention

[0003] This invention relates to a ureteric access sheath (UAS).

[0004] Background to the invention

[0005] Ureteric access sheaths are used in the field of endourology as a device to provide atraumatic access for flexible surgical instruments such as endoscopes to a kidney of a patient during intrarenal surgery procedures such as kidney stone treatment and to facilitate irrigation and drainage of the kidney during such procedures.

[0006] Existing ureteric access sheaths are thin walled, fairly rigid, but resiliently flexible straight tubes inserted into the ureter together with a tipped dilator fitted over a guidewire using so-called Seidinger Technique. Ureteric access sheaths are inserted from the bottom (in retrograde direction) through a ureter and placed either at or below the junction of ureter with renal cavity called pyelo-pelvic junction (PUJ) or are inserted just past the junction into the renal cavity (renal pelvis).

[0007] The inventor identified several difficulties and problems with the existing UAS. Firstly, occlusion or partial occlusion can occur due to valvular formation by flaps of loose tissue or due to stricture formation of ureter when the UAS is placed below the PUJ. Secondly, although not recommended due to the straight shape of the UAS, if the UAS is inserted further past the PUJ, the UAS may be blocked due to the curvature of the upper ureter or thirdly, if inserted even further, being blocked by the roof or wall of the renal pelvis. A straight shape UAS is required since the first, major, part of the ureter is generally straight.

[0008] In addition, up to 50% of insertions of UAS leads to ureteric trauma of which most are caused by the edge of the ureteric sheath. The UAS is inserted into the kidney with a snugly fitting dilator inside the UAS. The dilator is provided with central tubular hollow for at least one guidewire. The dilator is slid over the guidewire using the Seidinger technique. Known dilators have a flexible conical tip to help dilate the ureter. The outside diameter of the dilator and its tip is marginally smaller than inner diameter of ureteric access sheet to allow for easy insertion and removal of a dilator into and out of the access sheet. This difference in outer diameter of the dilator and inner diameter of ureteric access sheet forms an exposed shaving edge especially when the tip of the dilator is flexed while traversing through the torturous anatomy of ureter. Such a shaving edge can cause trauma to ureteric mucosa.

[0009] It is an object of the invention to address the problems and difficulties identified above.

[0010] General description of the invention

[0011] According to the invention there is provided a ureteric access sheath (UAS), which includes: a resiliently deformable tube provided with shape memory, which shape includes a rounded bend at its leading end which corresponds to the anatomical shape of a ureter’s entry up to and past the junction into the renal cavity (renal pelvis); and an access funnel at the trailing end of the tube.

[0012] The UAS may include a corresponding dilator, which dilator is provided with a tubular body with shape memory, which shape, optionally, includes a rounded bend at its leading end to generally correspond to the bend shape of the resiliently deformable tube of the UAS.

[0013] The dilator includes a dilator grip or dilator clip at its trailing end, which allows a user to rotate the dilator inside the UAS tube. Indicator markings may be provided on the grip or clip and the access funnel to indicate when the shape of the UAS and dilator corresponds in its natural resting shape and / or when the orientation of the dilator is 180 degrees opposite such that the shape of the UAS and dilator cancels each other to provide a generally straight UAS for initial insertion.

[0014] It is to be appreciated that the invention allows for the shape of the UAS to be manipulated during insertion to start off with a generally straight UAS with the respective memory shapes of the tube and the dilator in opposite orientations and when the bending part of the ureter is reached the dilator can be rotated such that the memory shapes corresponds in orientation to form a rounded bend which corresponds to the anatomy of the ureter. The dilator can then be removed leaving the access sheath on the correct anatomical orientation and shape.

[0015] The leading edge of the UAS tube may preferably be rounded or bevelled from the inner edge of the leading edge towards the outside surface of the tube.

[0016] It is to be understood that the tube is of known surgically acceptable material of standard UAS dimensions with a width ranging between 8F and 16F and required physical attributes such as stiffness, kink resistance and the like. The tube may preferably include a Teflon layer inside, stainless steel coil for reinforcement in the middle layer and Pebax or Polyurethane as outer layer.

[0017] It is to be understood that the access funnel is to provide access to the UAS for a dilator, ureteroscope and the like.

[0018] The dilator may be provided with a tip of flexible, compilable and shape memory deformable soft thermoplastic Polyurethane and which generally conical tip includes a two-part shape, with the leading part having a round pointed circular conical shape integral with the trailing part being in the shape of a right circular conical frustum, wherein the leading part is longer than the trailing part and wherein the angle of the cone relative to the axis of the tube is more acute for the trailing part than the leading part. It is to be appreciated that the leading part of the tip will be more flexible, compilable deformable than the trailing part of the tip which facilitates atraumatic navigation of the tip through a tortuous ureter. The trailing diameter of the trailing part of the shape memory deformable tip may preferably be larger than the inner diameter of the UAS tube such that the trailing surface of the tip, where it extends part the leading edge of the tube when in it operative position, bulges outwardly to obscure the leading edge of the tube. It is to be appreciated that this feature shields the inner wall of the ureter, in use, from a shaving edge formed by the leading edge of the tube and drastically reduces trauma to ureteric mucosa. This advantage may be increased if the edge of the tube is rounded or bevelled as described above. The dilator is tubular to accommodate a guide wire therethrough.

[0019] The invention also extends to a dilator as described above.

[0020] The invention also extends to a ureteric access system, which system includes a UAS as described above and a dilator as described above.

[0021] Detailed description of the invention

[0022] The invention is now described by way of example with reference to the accompanying drawings.

[0023] In the drawings:

[0024] Figure 1 shows a side view of a ureteric access sheath, in accordance with the invention;

[0025] Figure 2 shows a side view of a dilator for use with the ureteric access sheath, in accordance with the invention;

[0026] Figure 3 shows a side view of a ureteric access sheath with its dilator inserted in the same orientation, in accordance with the invention;

[0027] Figure 4 shows a side view of a ureteric access sheath with its dilator inserted in the opposite orientation to straighten the access sheath, in accordance with the invention; and

[0028] Figure 5 shows a detailed side view of the tip of the dilator protruding from the ureteric access sheath, in accordance with the invention. Referring now to the drawings, the ureteric access sheath, in accordance with the invention, is generally indicated by reference numeral 10.

[0029] The ureteric access sheath (UAS) 10 includes a resiliently deformable tube 12 provided with shape memory, which shape includes a rounded bend 14 at its leading end to correspond to the anatomical shape of a ureter up to the junction into the renal cavity (renal pelvis); and an access funnel 16 at the trailing end of the tube 12.

[0030] The UAS 10 includes a corresponding dilator 18, which dilator is provided with a tubular body 20 with shape memory, which shape includes a rounded bend 22 at its leading end to generally correspond to the bend 14 of the UAS 10.

[0031] The dilator 18 includes a dilator clip 24 at its trailing end, which allows a user to rotate the dilator inside the UAS tube 12. Indicator markings 26.1 and 26.2 may be provided on the clip 24 and the access funnel 16 to indicate when the shape of the UAS 10 and dilator 18 corresponds in its natural resting shape (Figure 3) and / or when the orientation of the dilator 18 is 180 degrees opposite such that the shape of the UAS 10 and dilator 18 cancels each other to provide a generally straight UAS 10 for initial insertion (Figure 4). The dilator is tubular to accommodate a guide wire 19 therethrough.

[0032] The leading edge of the UAS tube 18 is rounded from the top of the inner edge towards the outside surface of the tube.

[0033] The Tube comprise of a lining of PTFE and coil reinforcement of stainless steel with outer layer made of Polyurethane or Pebax. In another embodiment, a single extrusion of any one of the above polymeric material may be used.

[0034] The access funnel 16 is to provide access to the UAS 10 for a dilator 18, ureteroscope and the like.

[0035] The dilator 18 is provided with a tip 28 of flexible, compilable and resiliently deformable material such as Polyurethane like Tecoflex and which generally conical tip includes a two-part shape, with the leading part 30.1 having a round pointed circular conical shape integral with the trailing part 30.2 being in the shape of a right circular conic frustum, wherein the leading part is longer than the trailing part and wherein the angle of the cone relative to the axis of the tube is more acute for the trailing part than the leading part. It is to be appreciated that the leading part 30.1 of the tip 28 will me more flexible than the trailing part 30.2 of the tip which facilitates atraumatic navigation of the tip through a tortuous ureter.

[0036] The trailing diameter of the trailing part 30.2 of the deformable tip 28 is larger than the inner diameter of the UAS tube 12 such that the trailing surface of the tip, where it extends part the leading edge of the tube 12 when in it operative position, bulges outwardly to obscure the leading edge of the tube. Despite this bulge, of wider diameter than the internal diameter of the tube 12, the dilator 18 can be easily inserted in the tube 12 due to the soft deformability if the dilator tip 28.

[0037] It shall be understood that the examples are provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.

Claims

CLAIMS1 . A ureteric access sheath (UAS), which includes: a resiliently deformable tube provided with shape memory, which shape includes a rounded bend at its leading end which corresponds to the anatomical shape of a ureter’s entry up to and past the junction into the renal cavity (renal pelvis); and an access funnel at the trailing end of the tube.

2. A UAS as claimed in claim 1 , which includes a corresponding dilator, which dilator is provided with a tubular body with shape memory, which shape includes a rounded bend at its leading end to generally correspond to the bend shape of the resiliently deformable tube of the UAS.

3. A UAS as claimed in claim 1 or claim 2, wherein the dilator includes a dilator grip or dilator clip at its trailing end, which allows a user to rotate the dilator inside the UAS tube.

4. A UAS as claimed in claim 3, wherein the dilator grip or dilator clip includes indicator markings to indicate when the shape of the UAS and dilator corresponds in its natural resting shape and / or when the orientation of the dilator is 180 degrees opposite such that the shape of the UAS and dilator cancels each other to provide a generally straight UAS for initial insertion.

5. A UAS as claimed in any one of claims 2 to 4, wherein the leading edge of the UAS tube is rounded or bevelled from the inner edge of the leading edge towards the outside surface of the tube.

6. A UAS as claimed in any one of claims 2 to 5, wherein the dilator is provided with a tip of flexible, compilable and shape memory deformable soft thermoplastic polyurethane and which generally conical tip includes a two-part shape, with the leading part having a round pointed circular conical shape integral with the trailing part being in the shape of a right circular conical frustum, wherein the leading part is longer than the trailing part and wherein the angle ofthe cone relative to the axis of the tube is more acute for the trailing part than the leading part.

7. A UAS as claimed in claim 6, wherein the trailing diameter of the trailing part of the shape memory deformable tip is larger than the inner diameter of the UAS tube such that the trailing surface of the tip, where it extends part the leading edge of the tube when in it operative position, bulges outwardly to obscure the leading edge of the tube.

8. A dilator, which dilator is provided with a tubular body with shape memory, which shape includes a rounded bend at its leading end to generally correspond to the bend shape of the resiliently deformable tube of a UAS as claimed in any one of claims 1 to 7.

9. A ureteric access system, which system includes a UAS as claimed in any one of claims 1 to 7 and a dilator as claimed in claim 8.

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