Patent Description:
A ureteral access sheath adapted for insertion into a urethra includes an elongate tubular member having a proximal end and a distal end. One type of known ureteral access sheath consist of stainless steel sheath surrounded by a polytetrafluoroethylene (PTFE) inner coating.

<CIT> discloses medical devices and methods for making and using medical devices. An example medical device may include a guide extension catheter. The guide extension catheter may include a proximal member having a proximal outer diameter. A distal sheath member may be attached to the proximal member. The distal sheath member may have a distal outer diameter greater than the proximal outer diameter. The distal sheath member may have a proximal end, a distal end, and a longitudinal slit extending at least partially between the proximal end and the distal end. An expandable member may be attached to the distal sheath member and may extend along the longitudinal slit. The expandable member may be configured to shift between a first configuration and an expanded configuration.

<CIT> discloses an expandable transluminal sheath for introduction into a body.

<CIT> discloses a variable diameter catheter which is folded in a longitudinal manner in order to reduce the diameter for convenient and less traumatic insertion into a body orifice. The fold in the catheter is maintained by a slidably removable external sheath which aids in insertion of the catheter and in dispersion of an anti-infective medication.

<CIT> discloses a stretchable-diameter inserter for hemodynamic studies and related operations.

The invention provides a medical access sheath according to claim <NUM> and a corresponding method according to claim <NUM>. The following description is merely intended to be exemplary and is not intended to limit the scope of the claims.

Referring to <FIG>, there is shown a side perspective view of an apparatus <NUM> incorporating features of an example embodiment. In addition, any suitable size, shape or type of elements or materials could be used.

The apparatus <NUM> in this example embodiment is a medical ureteral access sheath. Referring also to <FIG>, the access sheath <NUM> in this example is configured to extend through a patient's urethra <NUM>, bladder <NUM> and ureter <NUM> and extend perhaps as far as the renal pelvis or ureteropelvic junction (UPJ) <NUM>. The ureteropelvic junction (UPJ, also known as the uretero-pelvic junction or ureteral pelvic junction) is the junction between the ureter and the renal pelvis of the kidney <NUM>. Ureteral access sheaths provide a continuous working channel, simplifying ureteroscopic procedures and protecting the ureter during multiple instrument exchanges. The sheath <NUM> is designed to facilitate ureteroscope insertion and re-insertion of instruments, such as an endoscope, allowing fragments of stones to be removed such as by a tool having a basket.

In this example the access sheath <NUM> comprises a flexible, elongated tubular shape having a proximal end <NUM> and a distal end <NUM>. Referring also to <FIG>, the sheath <NUM> has a first member <NUM>, a second member <NUM> and a cover <NUM>. In one type of example embodiment the sheath may comprise an inner liner on the interior facing surface of the first member <NUM>, such as comprised of polytetrafluoroethylene (PTFE) for example.

The first member <NUM> forms a flexible, structural core for the sheath. In this example, the first member <NUM> has a general tube shape comprised of a shape memory alloy, such as NITINOL for example. The first member <NUM> is a one-piece member having a first section <NUM> and a second section <NUM>. The first section <NUM> has a substantial semi-circular shape. The second section <NUM> has two movable flap portions 26a, 26b extending from opposite sides of the substantial semi-circular shape. The flap portions <NUM> are able to move relative to the first section <NUM> proximate the junctions <NUM>. In alternate example embodiments, the shape of the first section <NUM> and/or the second section <NUM> may be different, and/or the second section <NUM> may comprise more or less than two flap portions. The first member <NUM> helps to form a working channel <NUM> for insertion of tools through the sheath, such as an endoscope for example. The core <NUM> may be lined with PTFE as an hydrophilic coating to reduce friction.

The second member <NUM> is a one-piece member comprised of a suitable material such as a plastic or polymer material. The second member <NUM> has a substantial foil shape which is connected to the two opposing flap portions <NUM> and covers the gap <NUM> between the opposing flap portions <NUM>. The second member <NUM> is reconfigurable between a collapsed shape as shown in <FIG> and an expanded shape as shown in <FIG>. In the collapsed shape the second member <NUM> is located, at least partially, inside the channel <NUM>.

<FIG> shows the sheath in a natural, home configuration. <FIG> shows the sheath in an expanded configuration. In the expanded configuration the flap portions 26a, 26b have been deflected outward as indicated by arrows <NUM>; bending at the junctions <NUM>. The second member <NUM> is, thus, expanded between the enlarged gap between the ends of the flap portions <NUM>. This enlarges the channel <NUM> into a new larger channel <NUM>'.

Features as described herein may be used in a ureteral access sheath. With conventional access sheath technology, a physician has to select an access sheath size prior to the procedure. The size is selected depending on patient anatomy, scope size and the physician's preference to remove large stone fragments. Large access sheath are more traumatic to the ureter and sometimes it will be impossible to push the access sheath all the way up the UPJ (ureteropelvic junction). Features as described herein allow for a very slim sheath to be pushed up, but once in place a bigger lumen may be created, such as to allow for good fluid flow and large scopes/stones to be passed though the sheath. Features as described above allow for an access sheath with a flexible, NITINOL U-Shaped core, allowing for variable cross sectional area. Conventional access sheaths are based on a stainless-steel coil-reinforced sheath that prevents kinking, but does not allow for any flexibility in cross sectional area.

The sheath can either be self-expending, based on a NITINOL spring action, or it may open when an instruments/irrigation are passed through. <FIG> represent an embodiment where the sheath is expanded when an instruments/irrigation are passed through the channel <NUM>. Referring also to <FIG>, an embodiment is shown where a dilator <NUM> is used to control the sheath dimension. In this case, the dilator in the center would have a notch <NUM>, with the second member <NUM>' and at least part of the flap portions <NUM>' being folded inside that notch <NUM>. The access sheath may be loaded over a guidewire and pushed up the ureter. Once in place, the obturator may be removed and the sheath "flaps" would automatically unfold and open to a larger cross sectional area.

Features as described herein may provide a sheath comprising a slit or gap <NUM> and a foil <NUM> in the slit <NUM>; the foil <NUM> configured to be folded. Features as described herein may provide a dilator configured to be inserted to the sheath and keep the foil folded. The foil may be unfolded by removing the dilator from the sheath. The sheath may be expanded by the unfolded foil. Unlike nephrostomy, where an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system (renal pelvis), features as described herein may be used to extend an access sheath along the length of the ureter' perhaps up to the UPJ.

Referring also to <FIG>, another example is shown. <FIG> shows a sheath <NUM> having a core <NUM> made of shape memory alloy and a foil <NUM>. The foil <NUM> may have a locking part <NUM>. A dilator <NUM> is provided to retain the foil <NUM> in its collapsed shape at least partially inside the core <NUM>. The dilator <NUM> has a notch or groove along its length to retain the foil in its collapsed shape. The locking part <NUM> may help lock a portion of the foil <NUM> inside the dilator <NUM> until the dilator <NUM> is withdrawn. When the dilator <NUM> is removed as shown in <FIG>, the spring properties of the core <NUM> automatically expand the shape of the channel <NUM> into <NUM>', and the foil <NUM> unfolds and keeps the channel <NUM> substantially closed along the slit in the core <NUM>.

In one example embodiment a medical access sheath comprises a first member having a longitudinal length and a channel therethrough, where the first member comprises a slit along the longitudinal length, where the channel is configured to expand from a first cross-sectional size to a larger second cross-sectional size, and where the slit is configured to enlarge as the channel expands; and a second member connected to the first member proximate the slit, where the second member extends across the slit, and where the second member is configured to expand when the channel expands from the first size to the second larger size.

The medical access sheath may further comprise a cover along the longitudinal length of the first member, where the cover is substantially not located on the second member. The medical access sheath may comprise a shape memory material, where the second member comprises a polymer material. The medical access sheath may comprise a foil, where the foil is substantially folded at the slit when the channel has the first cross-sectional size, and where the foil is substantially unfolded when the channel has the second cross-sectional size. The medical access sheath may have a home configuration with the channel having the second cross-sectional size, where the sheath is configured to automatically expand from a collapsed configuration, with the channel having the first cross-sectional size, to the home configuration with the channel having the second cross-sectional size. The medical access sheath may have a home configuration with the channel having the first cross-sectional size, where the sheath is configured to expand when an instrument is passed through the channel from the home configuration to an expanded configuration with the channel having the second cross-sectional size. When the medical access sheath is in a collapsed configuration with the channel having the first cross-sectional size, at least a portion of the second member may be configured to be received in a receiving area of a dilator inserted into the channel. The first member may comprise a substantial semi-circular portion and two movable flap portions extending from opposite sides of the substantial semi-circular portion. An apparatus may be provided comprising the medical access sheath; and a dilator located in the channel, where the dilator comprises a receiving area along a longitudinal length of the dilator, where the receiving area has a portion of the second member located therein, and where the receiving area is configured to release the second member from a collapsed configuration to an expanded configuration as the dilator is slid out of the medical access sheath.

An example method may comprise changing a cross-sectional size of a channel in a tube of a medical access sheath from a first size to a different second size, where opposing ends of the tube along a longitudinal slit in the tube move relative to each other; and reconfiguring an expansion member, connected to the tube proximate the slit, to keep access to the channel through the slit closed as the size of the channel changes between the first and second sizes.

Changing of the cross sectional size may comprise removing a dilator from the channel. Changing of the cross sectional size may comprise inserting an instrument into the channel. Changing of the cross sectional size may comprise the tube automatically springing from a first collapsed configuration to a second expanded configuration. The expansion member may comprise a foil, where the foil is substantially folded at the slit when the channel has the first cross-sectional size, and where the foil is substantially unfolded when the channel has the second cross-sectional size. The tube may comprise a substantial semi-circular portion and two movable flap portions extending from opposite sides of the substantial semi-circular portion, where the flap portions move relative to the substantial semi-circular portion as the cross sectional size of the channel changes. The tube may comprise a shape memory material and where the expansion member is a foil, where the shape memory material provides a spring bias of the medical access sheath towards the first size or, alternatively, towards the second size. The expansion member may be a foil, and the foil may provide a spring bias of the medical access sheath towards the first size or, alternatively, towards the second size.

Another example embodiment may comprise a medical access sheath dilator configured to be inserted through a channel of a medical access sheath, where the dilator comprises a receiving area along a longitudinal length of the dilator, where the receiving area is configured to have an expandable portion of the medical access sheath located therein, and where the receiving area is configured to release the expandable portion from a collapsed first configuration to an expanded second configuration as the dilator is slid out of the medical access sheath. An apparatus may comprise the medical access sheath dilator; and the medical access sheath connected to the dilator. The medical access sheath may comprise a first member having a longitudinal length and a channel therethrough, where the first member comprises a slit along the longitudinal length, where the channel is configured to expand from a first cross-sectional size to a larger second cross-sectional size, and where the slit is configured to enlarge as the channel expands, and where the expandable portion is connected to the first member proximate the slit, where the expandable portion extends across the slit, and where the expandable portion is configured to expand when the channel expands from the first size to the second larger size.

A method of manufacturing a medical ureteral access sheath comprising providing a first member, where the first member comprises a longitudinal length and a channel therethrough, where the first member comprises a slit along the longitudinal length, where the channel is configured to expand from a first cross-sectional size to a larger second cross-sectional size, and where the slit is configured to enlarge as the channel expands; and connecting a second member to the first member proximate the slit, where the second member extends across the slit, and where the second member is configured to expand when the channel expands from the first size to the second larger size.

An example medical access sheath may comprise a first member comprising a longitudinal length and a channel therethrough, where the first member comprises a slit along the longitudinal length, where the channel is configured to expand from a first cross-sectional size to a larger second cross-sectional size, and where the slit is configured to enlarge as the channel expands; a second member connected to the first member proximate the slit, where the second member extends across the slit, and where the second member is configured to expand from a first configuration to the second configuration; and a third member removably located within the channel, wherein the third member is configured to keep the second member in the first configuration when the third member is located in the channel, and wherein the third member is configured to release the second member to the second configuration when the third member is removed from the channel.

An example medical apparatus may comprise a medical access sheath comprising a first member comprising a longitudinal length and a channel therethrough, where the first member comprises a slit along the longitudinal length, where the channel is configured to expand from a first cross-sectional size to a larger second cross-sectional size, and where the slit is configured to enlarge as the channel expands; and a second member connected to the first member proximate the slit, where the second member extends across the slit, and where the second member is configured to expand from a first configuration to a second configuration; and a dilator located in the channel, where the dilator comprises a receiving area along a longitudinal length of the dilator, where the receiving area comprises a portion of the second member located therein, and where the receiving area is configured to release the second member from a collapsed first configuration to an expanded second configuration as the dilator is slid out of the medical access sheath.

Claim 1:
A medical access sheath (<NUM>; <NUM>) comprising:
a first member (<NUM>; <NUM>) comprising a longitudinal length and a channel (<NUM>; <NUM>; <NUM>; and <NUM>') therethrough, where the first member comprises a gap (<NUM>) through the first member, where the first member comprises a first material; and
a second member (<NUM>; <NUM>'; <NUM>) connected to the first member, where the second member comprises a different second material,
where the first and second members form a tube, where the gap extends along a longitudinal length of the first member, where the first member forms a first portion of the tube, and where the second member extends across the gap such that the second member forms a second portion of the tube at the gap along the longitudinal length of the first member, where the second member is reconfigurable between a collapsed shape and an expanded shape, where in the expanded shape the medical access sheath has a first cross-sectional size and in the collapsed shape the medical access sheath has a smaller second cross-sectional size.