Patent Description:
BPH is a noncancerous disease that results in enlargement of the prostate. The prostate surrounds a section of the urethra adjoining the bladder, namely the prostatic urethra. Thus, as the prostate expands, it may press inwardly against and place pressure on the prostatic urethra and the neck of the bladder and so make it difficult to pass urine out of the bladder.

It is known to treat BPH in various ways including ongoing medication or, in particularly bad cases, surgery. However, both of these approaches are undesirable. For example, in the US alone more, than $<NUM> billion is spent annually on medication to manage BPH. Furthermore, surgical solutions can be particularly invasive and uncomfortable for the patient. Consequently, there has been a move in the art toward the use of expandable implants or stents that can be inserted into the urethra to react against, and hence to alleviate, the inward pressure applied to the urethra and bladder neck by the enlarged prostate.

Expandable implants provide a minimally invasive and low-cost solution for treating BPH. However, locating the implant in the correct position within the urethra is challenging for a clinician. If the implant is deployed incorrectly, it may not provide adequate symptom relief, may fail due to migration or excessive encrustation and may be challenging and invasive to recover the deployed expander from the patient's body.

An example of an expandable implant, or expander, for treating BPH is disclosed in <CIT>. The expander of <CIT> is designed to be positioned within the prostatic urethra of a patient between the bladder neck and external sphincter and then to expand laterally. The expander thereby applies a radially-outward force on the surrounding walls of the prostatic urethra to alleviate the symptoms of BPH.

Positioning the expander correctly within the prostatic urethra is challenging for a clinician as the expander must be positioned accurately both in a longitudinal direction and circumferentially or angularly. For example, the expander should be positioned longitudinally at a position between the bladder neck and the external sphincter and should also be oriented so as to engage the three lobes of the prostate. If the expander is deployed in an incorrect position, for example by being deployed accidentally or prematurely, then a complex procedure may be required to remove or reposition the expander. As a result, there is a need for a minimally-invasive delivery device that allows a clinician accurately to position and deploy an expandable implant within the prostatic urethra of a patient.

<CIT> describes a delivery device for delivering an expander to a target site within a body lumen such as the prostatic urethra. The delivery device comprises an ejection element with a triangular cross-section configured to engage and support the expander. The delivery device may be inserted into the urethra through the penis and advanced along the urethra to the target site. When the clinician is satisfied that the expander is in the correct position, the ejection element is advanced distally so that the expander is ejected from the delivery device.

Even with the assistance of the delivery device of <CIT>, it can be challenging to position the expander reliably and accurately within a patient's prostatic urethra. For example, advancing the ejection element could cause the expander to spring or jump forward upon deployment, thereby making it difficult to position the expander accurately within the prostatic urethra, both longitudinally and circumferentially. Relying on the expander simply to self-locate relative to the anatomy by virtue of its expansion can be unreliable and unpredictable.

Furthermore, a single-step delivery device such as that described in <CIT> can be susceptible to accidental deployment. Also, the device does not allow a clinician to pause or to reverse deployment of the expander if the clinician determines that the expander is not being positioned accurately within the target site.

<CIT> discloses a stent delivery catheter that comprises outer and inner sheaths and an endoscope serving as an imaging component within the stent. Provision is made to orient the stent on the inner sheath. However, the positioning of the endoscope relative to the sheaths and the stent does not facilitate effective imaging throughout the stent delivery process.

<CIT>, also to Mikus at al, discloses a stent delivery system for use with shape memory stents, in which stent expansion occurs when the stent is heated above the austenite transition temperature. A catheter includes a warming fluid system in which an endoscope used in the procedure can act as a fluid supply line and as a valve to control the flow of warming fluid to the stent. However, this complex system does not address the challenges of accurately and reliably positioning the stent.

<CIT> to Richardson discloses a stent delivery system with fibre-optic imaging capability. Similarly, <CIT> discloses a catheter system having imaging, balloon angioplasty and capability for guided stent deployment. In each case, the relative positions of the imaging system and the implant do not provide for effective imaging throughout the delivery process.

<CIT> discloses a neurovascular intervention device that, like Richardson and Jang et al above, does not provide for effective imaging throughout the delivery process due to the relative positions of the imaging system and a treatment device that can deliver an implant such as a stent. Indeed, simultaneous deployment and imaging may not be possible.

<CIT> discloses a stent delivery device and method that is said to be usable for various procedures, including treatment of BPH. The stent is located in a casing member for positioning and delivery but that casing member would block the view of the anatomy available through an imaging system of the device. In particular, the anatomy cannot be viewed relative to or in line with the distal end of the stent or from inside the stent. Consequently, if the device is used to treat BPH, the imaging system could merely locate the prostatic urethra but could not define and indicate specific alignment of the stent with anatomical features.

<CIT> discloses systems for delivering and deploying self-expanding stents that incorporate mechanisms for retrieving partially-deployed stents. <CIT> to Desrosiers also provides for recapture of a partially-deployed implant. <CIT> to Kao discloses a bi-directional stent delivery system. <CIT> to Roeder discloses an endoluminal stent on a guide wire. In each case, no effective provision is made for imaging the stent delivery location throughout the delivery process, and release and positioning of the stent may be unreliable.

<CIT> discloses a cystoscope delivery system for implanting a flexible expandable stent. The system comprises a sheath defining a central lumen and a secondary lumen extending therethrough and a rigid cystoscope extending distally through the central lumen. The stent is positioned circumferentially around the sheath and a release wire is positioned in and extending through the secondary lumen. When the release wire is pulled proximally, one or both ends of the stent are released to allow the stent to expand.

In general terms, the invention provides a delivery device for imaging and locating an expandable implant within the prostatic urethra of a patient when treating BPH. The delivery device comprises: an inner tube or other elongate element such as a rod; a tubular outer sleeve movable relative to the inner tube between a storage position and a deployed position; and an imaging device.

The outer sleeve surrounds the inner tube to define an annulus between them. The expandable implant is retained within the annulus when the outer sleeve is in the storage position. In the storage position, the outer sleeve at least partially surrounds the expandable implant such that the implant is retained on the inner tube. Thus, when in the storage position, the outer sleeve prevents the expandable implant expanding radially. Conversely, in the deployed position, the expander is uncovered by the outer sleeve to allow the expander to expand radially.

In the storage position, the imaging device allows a clinician to view the expander relative to the anatomy thereby making it easier for the clinician to align the expander correctly relative to the anatomy before releasing the expander from the device. The imaging device may be movable longitudinally relative to the outer sleeve and/or the inner tube or may be fixed against longitudinal movement relative to the outer sleeve and/or the inner tube. For example, the outer sleeve and the imaging device may be movable together relative to the inner tube between the storage position and the deployed position.

Broadly, the invention resides in a delivery device for deploying a self-expanding implant within a body cavity. The device comprises: at least one retention formation for holding the implant against axial or circumferential movement; an elongate longitudinally-extending outer element, radially outboard of the or each retention formation; and an imaging head disposed on a longitudinal axis that extends on a radially-inboard side of the or each retention formation.

The outer element is movable bidirectionally in opposed longitudinal directions relative to the or each retention formation, between: a storage position in which the outer element surrounds the implant and holds the implant engaged with, or prevents the implant disengaging from, the or each retention formation; and a partial-deployment position in which the outer element uncovers a distal portion of the implant while surrounding a proximal portion of the implant to continue holding the implant engaged with the or each retention formation.

Also, the imaging head is retractable proximally between: an advanced position when the outer element is in the storage position; and a retracted position when the outer element is in the partial-deployment position. The imaging head may be configured to define a field of view extending from a viewpoint that is radially inboard with respect to the or each retention formation and hence also inboard with respect to the implant.

The outer element may also be movable longitudinally, relative to the or each retention formation, into a full-deployment position in which the outer element uncovers the proximal portion of the implant to an extent sufficient to disengage the implant from the retention formation for radial self-expansion within the body cavity.

According to an aspect of the present invention there is provided a delivery device for locating an expandable implant for treating BPH within the prostatic urethra of a patient. A delivery tube of the delivery device comprises: a first elongate element that comprises or supports an imaging device; and a second elongate element surrounding the first elongate element to define an annulus therebetween; wherein the second elongate element is retractable relative to the first elongate element, between: a storage position in which the second elongate element is configured to surround the implant thereby retaining the implant within the annulus; a partially-deployed position in which the second elongate element is configured to partially uncover the implant; and a fully-deployed position in which the second elongate element is configured to uncover the implant to an extent sufficient to allow the implant to expand radially within the prostatic urethra.

When in the storage position, the distal image-receiving face of the imaging device may be locked at or near the distal extremity of the delivery device. This allows a clinician to view the anatomy, preferably with an uninterrupted field of view. When in the partially-deployed position, the distal face of the imaging device may be positioned within the interior of the expander, at a location that is proximal relative to the distal tip of the expander. This allows the clinician to view a distal portion of the expander relative to the anatomy, thereby making it easier for the clinician to align the expander relative to the anatomy.

The first elongate element may be, for example, an inner tube or rod and the second elongate element may be an outer sleeve or tube. The first and second elongate elements may be elliptical, for example circular, in cross-section and are preferably cylindrical.

The delivery device of the invention beneficially provides for accurate positioning and deployment of an expandable implant for treating BPH within the prostatic urethra of a patient. The outer sleeve may retain the expandable implant or expander within the annulus by surrounding the expander and preventing radial expansion of the expander until the expander is correctly located within the prostatic urethra.

In an embodiment, when in the partially-deployed position, a distal tip of the outer element, and a distal tip or face of the imaging device, may be positioned proximally with respect to a distal tip of the inner element. Beneficially, the partially-deployed position uncovers a portion of the expander while still retaining the expander in a compressed or stored configuration on the inner element. This allows a clinician to view the expander relative to the anatomy thereby making it easier for a clinician to align the expander relative to the anatomy. Furthermore, moving the outer element from the intermediate partially-deployed position to the fully-deployed position involves a smaller longitudinal movement than from the storage position to the fully-deployed position. This improves the accuracy of deployment of the expander.

In one embodiment, the delivery device may comprise a third elongate element located between the first, inner elongate element and the second, outer elongate element. The third elongate element may an intermediate tube such as a steering tube.

The delivery device may comprise one or more retention features for inhibiting movement of the expander. The retention feature advantageously retains the expandable implant relative to the inner tube or the intermediate tube within the annulus. This beneficially prevents longitudinal or angular movement of the expander relative to the inner tube or steering tube prior to deployment of the expander. In an embodiment, the retention feature may be located within the annulus.

In one embodiment the outer sleeve may surround the retention feature when in the partially-deployed position or in the storage position. This prevents radial expansion of the expander prior to full deployment of the expander. Furthermore, the outer sleeve may be returned from the partially-deployed position to the storage position if the clinician wishes to abort or pause deployment of the expander.

The retention feature may, for example, comprise at least one protrusion on the inner element. In an embodiment, the retention feature comprises a proximal protrusion and a distal protrusion located on the inner element. A slot for at least partially receiving the expander may be defined between the distal protrusion and the proximal protrusion. The expander may be received within the slot. For example, the expander may comprise an apex and one of the protrusions may be located between opposing sides of the apex when the expander is located on the inner element.

The inner element may comprise two, three or more sets of retention features spaced angularly and/or longitudinally that are configured to engage and retain the expander In another embodiment the protrusions may be located on or extending distally from an intermediate tube. The protrusions may be oriented on the inner element or intermediate tube such that the expander is orientated substantially correctly when the delivery device is inserted into the urethra in an upright or otherwise known or predetermined orientation.

A gap may be defined between a top or radially outer surface of a retention feature and a radially inner surface of the outer sleeve when the outer sleeve is in the storage position or in the partially-deployed position. The gap is narrower than a radial thickness of a part of the expander to be engaged by the retention feature. For example, the delivery device the expander may comprise a wire retained by the retention feature and the gap may be smaller than the thickness of the wire. The gap beneficially provides clearance between the retention feature and the outer sleeve to allow the outer sleeve to move freely relative to the inner tube. Furthermore, the gap may allow fluids to flow along the annulus if the annulus forms part of an irrigation channel.

The delivery device further comprises a handle connected to a proximal end of the inner and/or outer elements to allow the delivery device to be held and gripped by a clinician. The handle is operable to move the outer sleeve and the imaging device relative to the or each retention formation between a storage position, a fully-deployed position and a partially-deployed position.

In an embodiment, the handle may comprise a proximal grip and a distal grip. In another embodiment, the handle may comprise a two or three finger power grip, similar to that of an endoscope, in which the middle and or ring and little fingers hold the endoscope handle and the index and or middle fingers operate a steering and other mechanisms.

The handle may comprise a lever, catch or other latch that is movable between a locked position and an unlocked position to serve as a detent. When the latch is in the locked position, the outer element is locked in the storage position. The latch may be movable into an intermediate position and when the lever is in that position, the outer sleeve can be moved from the storage position to the partially-deployed position. The latch may also be movable into a fully-deployed position. When the latch is in the fully-deployed position, the outer element can be moved between the partially-deployed position and the fully-deployed position.

When the expander is retained within the annulus in use, a distal end of the inner element may be located distally or in longitudinal alignment with respect to a distal end of the expander. Alternatively, a distal end of the inner element may be located proximally with respect to a distal end of the expander and distally with respect to a proximal end of the expander.

Beneficially, the inner element provides support to the expander when the expander is retained on the inner element, such that longitudinal struts of the expander are maintained in generally parallel relation when the expander is in the stored configuration. This advantageously promotes radial expansion of the expander during deployment and further reduces the possibility of the expander becoming dislodged from the retention features. Furthermore, the inner element supports the expander when the delivery tube is being inserted into, and along, the urethra. This beneficially prevents the expander being compressed further by the urethra, which could otherwise cause the expander to disengage from the retention features.

The inner element may comprise an inner lumen that may extend along the length of the inner tube. Furthermore, the inner lumen may act as an irrigation channel for clearing the field of view and draining fluids from the bladder and/or the urethra. The imaging device may be at least partially received within the inner lumen, or the inner element may be an imaging device. The imaging device may comprise an imaging chip or fibre optics or the imaging device may comprise a telescope. For example, an imaging chip may be connected to an image display device and wires connecting the imaging device to the image display device and a power source may run through the inner lumen. The imaging device may be in a fixed circumferential position relative to the inner element that retains the expander such that the imaging device cannot rotate, hence facilitating accurate longitudinal and angular alignment of the implant with the anatomy.

In the storage configuration, all or most of the expander may be positioned proximally relative to, and hence outside, the field of view of the imaging device. This is beneficial as the imaging device may generate images of the patient's anatomy to allow the clinician to assess the anatomy prior to the deployment of the expander. However, the field of view of the imaging device may include at least a portion of the expander when the expander is in its stored configuration on the inner tube. The viewpoint, being the origin of the field of view of the imaging device, may be from the inner side of the expander. This is beneficial as the imaging device can then receive images of the expander relative to the anatomy of the patient. This allows the clinician to locate and position the expandable implant accurately relative to the anatomy by using the images from the imaging device.

The imaging device may, for example, be movable relative to the inner element but may be fixed relative to the outer element. As such, the imaging device may be moved relative to the inner element when the outer sleeve is moved between the storage, partially-deployed and fully-deployed positions. In an embodiment the imaging device may be fixed relative to the inner and outer elements in such a way that it cannot rotate circumferentially about a central longitudinal axis of the delivery tube. This allows a clinician to locate the expandable implant accurately in a certain axial position relative to the anatomy without rotational movement, ensuring precise deployment.

In another embodiment, the inner element, and optionally the imaging device, is movable longitudinally relative to an intermediate tube between a distally-advanced position and a proximally-retracted position. A distal tip of the inner element may be positioned distally with respect to the distal tip of the outer element when the inner tube is in the distally advanced position. The outer element may be outside a field of view of the imaging device when the inner element is in the distally-advanced position. The imaging device may, however, be configured such that its field of view captures at least a distal portion of the expander when the inner element is in the proximally-retracted position.

The outer element may comprise graduation marks spaced at longitudinal to provide a visual aid to the clinician when positioning the expander in the desired longitudinal position. The graduation marks could, however, be on the inner element if the outer element is transparent such that the graduation marks on the inner element are visible to the clinician.

In an embodiment, the delivery device may comprise an expandable implant. The implant may be supported by the first elongate element and at least partially covered by the second elongate element.

Also disclosed is a method of deploying a self-expanding implant within a patient's body cavity. The method comprises: inserting an elongate delivery sheath of an implant delivery system into the cavity with an imaging head of the delivery system in a distally-advanced position and with the delivery sheath in a storage position in which the implant is retained within and covered by the delivery sheath; navigating the implant to a target site within the cavity, guided by imagery of the patient's anatomy taken from a first viewpoint defined by the distally-advanced imaging head; retracting the delivery sheath proximally, relative to the implant, to a partial-deployment position in which the implant is at least partially uncovered while still being retained by the delivery sheath; retracting the imaging head proximally, relative to the implant, into a retracted position in which the imaging head defines a second viewpoint that is within and surrounded by the implant; and positioning the implant at the target site guided by imagery of the implant relative to the surrounding anatomy, taken from the second viewpoint defined by the proximally-retracted imaging head.

The patient's anatomy may be imaged from the first viewpoint substantially uninterrupted by the implant or by the delivery sheath. The implant may be imaged relative to the surrounding anatomy from the second viewpoint disposed proximally relative to a distal end of the implant, substantially uninterrupted by the delivery sheath. The outer element and the imaging head may be moved together in the proximal direction.

Also disclosed is a method of deploying an expandable implant within a patient's urethra. The method comprises: inserting a delivery tube into the urethra with the implant and an imaging device retained within and covered by the delivery tube; retracting the delivery tube proximally, relative to the implant, to a partially-retracted position in which the implant is at least partially uncovered while still being retained by the delivery tube; using the imaging device to image the implant together with the patient's anatomy; positioning the implant at a target site within the urethra; and deploying the implant at the target site by further retracting the delivery tube to an extent sufficient to release the implant from the delivery tube.

More specifically, the delivery tube images the anatomy by a camera or other image sensor that sits within an innermost channel of the delivery system and within the inner diameter of the implant. In the partially-retracted position, the implant can be lined up with the anatomy using the camera that generates images from within the implant. After deploying the implant at the target site by further retracting the delivery tube, the camera can image the deployed device within the anatomy with no further manipulation of handle components being required by the user.

Deploying the expander in a two-stage deployment process and under direct vision from the imaging device beneficially reduces the risk of the clinician deploying the implant incorrectly. Furthermore, the partially-retracted position allows the implant to be aligned with the anatomy when it is partially uncovered and when the imaging device is located inside the implant. Imaging the expander with an imaging device located within the implant allows concentric imaging of the expander and the anatomy so that an alignment step can be completed with the anatomy and expander in the same plane aligned with a central axis, which facilitates accuracy of deployment.

Inserting the delivery tube when the implant is covered by an outer sleeve is beneficial as it allows the delivery device to be easily inserted into the urethra without the implant potentially catching on the anatomy. Advantageously, the delivery tube may have a rigid distal tip portion to manipulate and straighten the prostatic urethra, ensuring that the prostatic urethra, the surrounding anatomy and the expander implant will be substantially concentric. Optionally, the delivery tube can steer the implant in response to control inputs from its proximal end.

The method may comprise positioning the implant at the target site at a longitudinal position in the urethra between the patient's bladder neck and external sphincter. The method may comprise advancing a distal end of the delivery tube distally along the urethra to, or distally beyond, the bladder neck. The distal end of the delivery tube may therefore be advanced into the bladder. This allows the anatomy along the length of the urethra to be viewed as the delivery device is advanced along the urethra. This allows the clinician to check for any obstructions within the urethra and to view the prostatic lobes.

The method may then comprise pulling the distal end of the delivery tube back away from the bladder neck in a proximal direction. The bladder neck may thereby be used as a datum for positioning the implant at an appropriate longitudinal position in the prostatic urethra. The delivery tube may comprise graduation marks with which to position the implant in a clinically acceptable position relative to the bladder neck datum prior to deployment.

Positioning the expandable implant may also comprise turning or rotating the implant about a longitudinal axis of the delivery tube when positioning the implant at the target site. The implant may be rotated to align the implant with at least one prostatic lobe of the patient. For example, the implant may comprise at least one apex and may be rotated to align the at least one apex with a prostatic lobe. The implant may be secured relative to the delivery tube such that rotating the delivery tube rotates the expander. The method may comprise aligning at least one apex of the implant with the or each prostatic lobe.

The delivery tube may comprise an inner tube that is static relative to the prostatic urethra when the delivery tube is moved from the partially-deployed configuration to the fully-deployed configuration. The method may comprise holding the implant substantially stationary relative to the prostatic urethra when further retracting the delivery tube from the partially-deployed to the fully-deployed position. This is beneficial as the expandable implant may be secured to the inner tube when in the partially-deployed configuration and thus the expander may remain in a substantially unchanged longitudinal position when the delivery device is moved to the fully-deployed configuration. This improves the accuracy of deployment of the implant from a stored state to a deployed state within the prostatic urethra.

Deploying the implant may comprise expanding the implant radially. The implant may be expanded radially from a stored or compressed state to a deployed or expanded state. The implant may be deployed by moving an outer sleeve longitudinally relative to the implant. The implant may thus be unsheathed or uncovered to allow the implant to expand radially.

Moving the delivery tube to the partially-deployed configuration may comprise operating a safety catch, latch or button to enable the delivery tube to be moved or reconfigured in that way. The method may further comprise operating the safety catch again, for example moving the safety catch to a further position, to enable the delivery tube to be further retracted from the partially-retracted position.

The method may comprise retaining the implant by engagement with retaining formations that remain covered by the delivery tube in the partially-retracted position but that are exposed by said further retraction of the delivery tube to release the implant. The method may further comprise advancing the delivery tube distally to cover the retaining formations again before removing the delivery tube from the urethra. Thus, the method may comprise moving the delivery tube from the fully-deployed configuration to the storage configuration before removing the delivery tube from the urethra.

The method may comprise viewing the implant relative to the urethra from a viewpoint within the implant and disposed proximally relative to a distal end of the implant, when the delivery tube in the partially-retracted position.

The method may comprise aligning at least one apex of the implant with the patient's verumontanum. The method may comprise locating the verumontanum between laterally-spaced longitudinally extending members or struts of the implant. The method may comprise pulling back the implant proximally while avoiding contact of the apex with the verumontanum. Apices of the implant may be aligned with respective lobes of the prostate, being lateral lobes or a transition zone and a median lobe.

The method may further comprise steering the delivery tube or manipulating the anatomy by bending at least a distal portion of the delivery tube along its length.

The method described herein has numerous advantages. For example, the initial field of view of an imaging device need not show the stored implant upon arriving at the prostatic urethra, hence giving an unobstructed view of the anatomy. This helps a clinician to assess the anatomy and to make a judgement on positioning the implant in accordance with the length of the prostatic urethra and the height of the bladder neck height of a particular patient.

Conversely, the positioning step may allow concentric imaging of the implant and the anatomy so that an alignment step can be completed accurately and easily, ensuring that the implant and the anatomy are substantially symmetrical about the same vertical plane and have substantially the same central axis during the deployment step.

Thus, the positioning step allows a view of the implant and the anatomy at the same axial location in the anatomy. The camera lens or other image sensor and the distal tip of the expander, toward the bladder neck, are at the same longitudinal position relative to each other and can travel in this relative position, always locked together. This ensures consistent accuracy in positioning as the implant cannot move on the delivery system during introduction and positioning steps due to the retention features on the distal tip portion of the delivery system.

Arranging the lens or other image sensor within the implant facilitates correct positioning of the implant relative to each critical anatomical feature - namely the bladder neck, the lobes of the prostate and the verumontanum - at the same time.

Viewing of the implant and the anatomy in the same plane, not from a viewpoint behind or beside the implant, facilitates precision of alignment.

A rigid distal tip of the delivery system straightens out the prostatic urethra and ensures that the expander and the prostatic urethra, and therefore the surrounding anatomy, will be substantially concentric. Thus, the camera lens or other image sensor is oriented and located within the implant, imaging beneficially from the inside outwardly. More generally, a steerable tip allows for positioning to suit the curvature, angle or inclination of the prostatic urethra. In this respect, embodiments of the invention combine a steering ring with implant holding features in a manner that is not suggested in the prior art.

Advantageously, no balloon or other positioning device is required in the bladder, hence reducing the duration and complexity of the procedure. Nor is there a need for deployment in the bladder and pulling back, which could also damage the bladder neck.

A simple handle mechanism can effect deployment. The implant is pre-formed and there is no need to adjust or to form the implant in situ. Parts of a delivery handle lock together and control the movement and organisation of delivery sheaths and an imaging sheath. The delivery sheath has features to hold the implant in a locked position relative to the imaging component. The outer sheath moves back or is dimensioned such that it does not obscure viewing of the implant and anatomy during deployment.

The skilled reader will appreciate that whilst the expander described herein is for use in treating BPH, the delivery system of the invention could be used in other applications in which an expandable implant is to be located within a body lumen.

In general terms, embodiments of the invention relate to a delivery device for deploying an expandable implant, or expander, within the prostatic urethra of a patient to alleviate the symptoms of BPH. In a broad sense, the delivery device comprises a handle operatively connected to an elongate delivery tube. The delivery tube comprises an inner tube surrounded by an outer sleeve or sheath with an annulus defined between them. The expander may be retained in a compressed or stored configuration within the annulus. A retention feature positioned at a distal end region of the inner tube retains the expander relative to the inner tube in the compressed or stored configuration within the annulus. An imaging component is housed in or supported by the inner tube.

In use, the delivery tube is inserted into a patient's urethra through the penis and advanced along the urethra to the prostatic urethra. When satisfied that the distal end portion, and thus the expander, is accurately positioned within the prostatic urethra, the clinician operates the handle to retract the outer sheath, thereby allowing the expander to expand and deploy within the prostatic urethra.

Deployment of the expander from the delivery device may be a two-stage process in which the outer sheath is first retracted to a partially-deployed position. In the partially-deployed position, the expander is at least partially unsheathed but remains attached to the delivery device. If the clinician is satisfied that the expander is located correctly following an imaging step and an alignment step, the outer sheath may be moved to the fully-deployed position to release the expander from the delivery device, thereby locating the expander at the target site within the body lumen, in this example the prostatic urethra.

The delivery device advantageously allows the expander to be positioned accurately within the anatomy before being deployed within the prostatic urethra in a controlled manner under direct vision. Controlled deployment beneficially prevents the expander being deployed inadvertently and ensures that the expander is accurately positioned within the prostatic urethra upon and after deployment.

To place embodiments of the invention in a suitable context, reference will firstly be made to <FIG> which shows a schematic diagram of an expandable implant or expander <NUM> suitable for use with embodiments of the present invention. The skilled reader will understand that the expander <NUM> shown in <FIG> is by way of example only and that the delivery device described herein may be suitable for use, or may be adapted for use, with other implants.

The expander <NUM> comprises a single nitinol wire arranged to form a sinusoidal ring. The expander <NUM> can be moved or transformed elastically between an expanded or deployed state as shown in <FIG> and a compressed or stowed state as shown in <FIG>. When released, expander <NUM> will move or transform itself by elastic recovery from the compressed or stowed state of <FIG> into the expanded or deployed state of <FIG>. Specifically, the nitinol wire ring of the expander <NUM> acts with superelastic shape memory properties such that when in the compressed state the expander <NUM> exerts an outward radial force urging itself to the expanded state.

The expander <NUM> has a proximal end <NUM> comprising three proximal prongs <NUM> with respective apices <NUM> and a distal end <NUM> comprising three distal prongs <NUM> with respective apices <NUM>. The apices <NUM>, <NUM> of the distal and proximal ends <NUM>, <NUM> are joined, in circumferential alternation, by longitudinal struts <NUM>.

When the expander <NUM> is in the contracted or compressed state shown in <FIG>, the diameter of the sinusoidal ring defined by the expander <NUM> is reduced such that the expander <NUM> may be advanced along the urethra of a patient with minimal discomfort. The expander <NUM> is delivered to the prostatic urethra <NUM> in that contracted or delivery state.

Referring now to <FIG>, the expander <NUM> is shown in use in the treatment of benign prostatic hyperplasia (BPH) within the prostate <NUM>. In use, the expander <NUM> is located within the prostatic urethra <NUM> between the bladder neck <NUM> and the external sphincter <NUM>. When located in this position, the expander <NUM> exerts an outward radial force against the surrounding walls of the prostatic urethra <NUM> to promote the flow of urine from the bladder <NUM>.

Positioning the expander <NUM> at the correct longitudinal position between the bladder neck <NUM> and the external sphincter <NUM> is challenging and care must be taken to ensure that the expander <NUM> is suitably positioned prior to deployment. Positioning the expander <NUM> too close to either the bladder neck <NUM> or the external sphincter <NUM> is undesirable as their muscle action could otherwise cause the expander <NUM> to migrate over time.

As shown in <FIG>, the expander <NUM> is orientated angularly such that the verumontanum <NUM> and the seminal ducts <NUM> are unobstructed by the wire of the expander <NUM>, thus preserving the patient's sexual function. Furthermore, the longitudinal struts <NUM> of the expander <NUM> are oriented to engage each respective lobe of the prostate <NUM>, thereby exerting an outward radial force on each lobe to maintain an open passage between the bladder neck <NUM> and the external sphincter <NUM>.

Turning now to <FIG>, a delivery device <NUM> for positioning the expander <NUM> within the prostatic urethra <NUM> is shown. The delivery device <NUM> comprises a handle <NUM> operatively connected to an elongate delivery tube <NUM>. The delivery tube <NUM> is configured to at least partially receive the expander <NUM> in a compressed state and to deploy the expander <NUM> within the prostatic urethra <NUM> of a patient. The delivery tube <NUM> may be inserted into the urethra via the patient's penis and advanced along the urethra to a target site, in this example the prostatic urethra <NUM>, where the expander <NUM> may be deployed.

<FIG> shows a schematic view of the distal end portion <NUM> of the delivery tube <NUM> located within the prostatic urethra <NUM>. As shown in <FIG>, the delivery tube <NUM> comprises an inner tube <NUM> that is surrounded by an outer sleeve <NUM>. An annulus <NUM> is defined between the inner tube <NUM> and the outer sleeve <NUM> and the expander <NUM> is located within the annulus <NUM>. The outer sleeve <NUM> surrounds the expander <NUM> thereby preventing the expander <NUM> from expanding from the stored configuration to the deployed configuration. The annulus <NUM> serves to retain the expander <NUM> at the distal end region <NUM> of the delivery tube <NUM> and further acts as an irrigation channel along which fluids may be irrigated to or from the urethra and/or bladder <NUM>.

The handle <NUM> is operatively coupled to the delivery tube <NUM> such that operating the handle <NUM> allows a clinician to move the outer sleeve <NUM> longitudinally relative to the inner tube <NUM>. The lumen <NUM> on the inner tube <NUM> may extend through the handle <NUM> and terminate at a proximal end of the handle <NUM> in a telescope plug <NUM> suitable for receiving an imaging device, such as a telescope. The plug <NUM> may be configured to retain a telescope within the inner lumen <NUM> such that the telescope can provide images from the distal end <NUM> of the delivery tube <NUM>. Beneficially, the plug <NUM> is positioned on the proximal handle <NUM> which is connected to the inner tube <NUM> and outer tube <NUM>. As such, the telescope is fixed relative to the outer tube <NUM> and always moves with it so that the telescope also moves longitudinally relative to the inner tube <NUM> when the clinician operates the handle <NUM>. The plug <NUM> advantageously provides a datum against which the position of the expander <NUM> may be measured in relation to the distal tip of the telescope and the outer sleeve <NUM>.

The outer sleeve <NUM> is movable between a sheathing or storage position in which the expander <NUM> is surrounded by the outer sleeve <NUM> along its length, as shown in <FIG>, and a deployed or retracted position in which the outer sleeve <NUM> is moved proximally relative to the inner tube <NUM> to uncover the expander <NUM> carried by the delivery tube <NUM>. Furthermore, the outer sleeve <NUM> is movable to, and can be held temporarily at, an intermediate or partially-deployed position in which the expander <NUM> is partially uncovered but retained on the inner tube <NUM> as is described in further detail below.

The inner tube <NUM> comprises retention formations <NUM> for preventing longitudinal or angular movement of the expander <NUM> relative to the inner tube <NUM> when the expander <NUM> is being retained in the stored configuration within the delivery tube <NUM>. The retention formations <NUM> are positioned at the proximal end <NUM> of the expander <NUM> at a longitudinal position such that the entire length of the expander <NUM> is retained within the outer sleeve <NUM> at the distal end portion <NUM> of the delivery tube <NUM> when the outer sleeve <NUM> is in the storage configuration. The retention formations <NUM> keep the expander <NUM> in fixed relation to the distal lens of the telescope or other distal imaging device.

<FIG> shows an embodiment in which the distal end portion <NUM> of the inner tube <NUM> extends along the longitudinal length of the expander <NUM> such that the expander <NUM> is supported along substantially its entire length by the inner tube <NUM>. Supporting the expander <NUM> along its full length is beneficial when the expander <NUM> is being advanced along the urethra as it prevents the expander <NUM> deforming and potentially disengaging the retention formations <NUM>. However, in another embodiment, the distal tip <NUM> of the inner tube <NUM> may extend distally from the retention formations <NUM> only part-way along the length of the expander <NUM>.

Turning now to <FIG>, a perspective view of the underside of the distal end portion <NUM> of the inner tube <NUM> is shown with the outer sleeve <NUM> and imaging device removed for clarity. The inner tube <NUM> is an elongate plastics tube comprising the distal end portion <NUM> opposed to a proximal end coupled to the handle <NUM>. The inner tube <NUM> comprises a hollow inner lumen <NUM> that may be used to receive the imaging device, for example the telescope or an imaging chip with a related support and electronics.

As shown in <FIG>, the inner tube <NUM> comprises two sets of retention formations <NUM>. The retention formations <NUM> are configured to prevent longitudinal or rotational movement of the expander <NUM> relative to the inner tube <NUM> and to prevent rotational movement of the expander <NUM> relative to the telescope. The retention formations <NUM> are located on the distal end portion <NUM> of the inner tube <NUM>.

Typically, the retention formations <NUM> are positioned on the inner tube <NUM> at a position proximal of the distal tip <NUM> by a distance in excess of the length of the expander <NUM>. This is beneficial as when the expander <NUM> is in the stored position, the inner tube <NUM> may provide an orifice or aperture for a telescope to visualise the anatomy, with or without the expander also being visible, and can support the expander <NUM> along the entire length of the expander <NUM>. This maintains the longitudinal struts <NUM> generally parallel to each other when in the stored position, thus promoting smooth deployment of the expander <NUM> from the stored position to the expanded position.

Alternatively, when the inner tube <NUM> is shorter than the outer sleeve <NUM> such that the outer sleeve <NUM> overhangs the inner tube <NUM>, the retention formations <NUM> may be located such that the distal end <NUM> of the expander <NUM> also overhangs the distal end of the inner tube <NUM>. In this embodiment, the inner tube <NUM> only provides support to a portion of the expander <NUM>. However, the support provided by the inner tube <NUM> is again sufficient to maintain the longitudinal struts <NUM> generally parallel to each other when the expander <NUM> is in the stored configuration.

The retention formations <NUM> each comprise a distal protrusion <NUM> and a proximal protrusion <NUM> that define a retention slot <NUM> between them. The slot <NUM> is configured to receive a proximal apex <NUM> of the expander <NUM> so as to retain the expander <NUM> on the inner tube <NUM>. When the expander <NUM> is located on the inner tube <NUM> in the compressed configuration, the proximal prong <NUM> of the expander <NUM> wraps around and engages the distal protrusion <NUM> of the retention formation <NUM>. This inhibits longitudinal movement of the expander <NUM> in the distal direction and also rotational movement of the expander <NUM> relative to the inner tube <NUM>. The proximal apex <NUM> may also abut the proximal protrusion <NUM>, thereby inhibiting movement of the expander <NUM> longitudinally in the proximal direction.

<FIG> is a longitudinal sectional view of a retention formation <NUM> with the expander <NUM> in the stored configuration and surrounded by the outer sleeve <NUM>. The retention formation <NUM> prevents longitudinal or rotational movement of the expander <NUM> relative to the inner tube <NUM>. As shown in <FIG>, the outer sleeve <NUM> of the delivery device <NUM> surrounds the expander <NUM> thereby preventing radially-outward expansion of the expander <NUM> to the deployed position. <FIG> shows the outer sleeve <NUM> in a storage or partially-deployed position in which the expander <NUM> is encircled by the outer sleeve <NUM> at least in alignment with the retention formations <NUM>, thereby retaining the expander <NUM> in the stored configuration on the inner tube <NUM>.

The distal protrusion <NUM> and a proximal protrusion <NUM> of the retention feature <NUM> are shown in detail in <FIG>. The protrusions <NUM>, <NUM> each comprise a ramped wall <NUM>, <NUM> such that the retention feature <NUM> has ramped walls <NUM>, <NUM> on the distal and proximal sides of the retention feature <NUM>.

The ramped walls <NUM>, <NUM> of the protrusions <NUM>, <NUM> minimise the potential for the retention features <NUM> to re-engage or catch on the expander <NUM> after the expander <NUM> has been deployed within the prostatic urethra <NUM>. The ramped walls <NUM>, <NUM> are opposed about the retention slot <NUM> of the retention feature <NUM>. Thus, if the inner tube <NUM> is moved longitudinally relative to the deployed expander <NUM> when the outer sleeve <NUM> is in the deployed position, the ramped surfaces <NUM>, <NUM> may contact the expander <NUM> but are unlikely to catch or snag on the expander <NUM>. This is advantageous as catching or snagging the expander <NUM> once it is deployed could cause the expander <NUM> to move longitudinally within the anatomy, which could result in the expander <NUM> being positioned incorrectly.

Furthermore, the proximal protrusion <NUM> and distal protrusion <NUM> comprise generally vertical walls <NUM>, <NUM> that define the sides of the slot <NUM> such that the slot <NUM> has a U-shaped profile. The vertical walls <NUM>, <NUM> of the protrusions <NUM>, <NUM> advantageously act as a guide to radial expansion of the expander <NUM> when the expander <NUM> is being deployed. Specifically, the walls <NUM>, <NUM> confine expansion movement of the expander <NUM> to a substantially radial direction when the expander <NUM> is being deployed, thereby minimising unintended longitudinal movement of the expander <NUM> relative to the inner tube <NUM> during deployment.

The slot <NUM> defined by the distal protrusion <NUM> and the proximal protrusion <NUM> may be dimensioned to have a clearance fit with the wire of the expander <NUM>. In another embodiment, the slot <NUM> may have an interference fit with the wire of the expander <NUM> such that the slot <NUM> applies a retaining force on the expander <NUM>. However, the retaining force applied by the slot <NUM> should be less than the radially-outward self-expansion force of the expander <NUM> such that the expander <NUM> may still be deployed when the outer sleeve <NUM> is pulled back to the deployed position.

As shown in <FIG>, a gap <NUM> is provided in the annulus <NUM> between the top or radially-outer surfaces of the protrusions <NUM>, <NUM> and the inner surface of the outer sleeve <NUM>. The width of the gap <NUM> is less than the diameter of the wire of the expander <NUM> such that the expander <NUM> is retained within the slot <NUM> when the outer sleeve <NUM> is in the storage position. The expander <NUM> may contact the inner surface of the outer sleeve <NUM> when the expander <NUM> is being retained in the stored position by the outer sleeve <NUM> and retention formations <NUM>.

<FIG> is a cross-sectional view of the inner tube <NUM> and the retention formations <NUM>. As shown in <FIG>, the inner tube <NUM> comprises two retention formations <NUM> for retaining the expander <NUM> on the inner tube <NUM>. The retention formations <NUM> are spaced apart from each other angularly by about <NUM>° such that the retention formations <NUM> may engage two of the proximal prongs <NUM> of the expander <NUM>. More generally, with reference to the circumference of the inner tube <NUM>, the retention formations <NUM> are at approximately the four to five o'clock and seven to eight o'clock positions respectively.

It will be noted that, in this example, the retention formations are on the underside of the inner tube <NUM>, in substantially symmetrical positions about a central longitudinal plane of the inner tube <NUM>, but that no retention formation <NUM> is provided on top of the inner tube <NUM>. This is in case the anterior prostatic urethra contacts and presses on the upper surface of the inner tube <NUM> during deployment of the expander <NUM>, in which case such pressure could prevent the expander <NUM> disengaging from a retention formation <NUM> positioned on top of the inner tube <NUM>. However, this configuration of the retention formations <NUM> is not essential. Where there is less concern as to reliable deployment, retention features could be positioned anywhere on the inner tube <NUM>, including its top; for example, three substantially equi-spaced retention features would be possible.

The skilled reader will understand that the retention formations <NUM> may be spaced angularly by any angle that is suitable for engaging and retaining an expander on the inner tube <NUM>. Furthermore, the skilled reader will understand that the inner tube <NUM> may comprise more or fewer than two retention formations <NUM> to engage and retain the expander <NUM>.

The retention formations <NUM> are positioned angularly on the inner tube <NUM> such that when the delivery tube <NUM> is inserted into the urethra with the handle <NUM> in an ergonomic, generally upright position, the expander <NUM> is already oriented to engage the lobes of the prostate <NUM>. This is beneficial as the clinician is only required to make small adjustments, if any, to the angular position of the expander <NUM> when positioning the expander <NUM> within the prostatic urethra <NUM>.

<FIG> is a side view of the handle <NUM> of the delivery device <NUM>. The handle <NUM> is connected to the proximal end of the delivery tube <NUM> such that the handle <NUM> may be held by a clinician and used to position the delivery tube <NUM>. Furthermore, the handle <NUM> is operable to control the position of the outer sleeve <NUM> relative to the inner tube <NUM> such that the outer sleeve <NUM> may be moved between the storage position, the partially-deployed position and the fully-deployed position thereby allowing a clinician to deploy the expander <NUM> by operating the handle <NUM>. The handle <NUM> is also operable to control the position of the imaging sheath relative to the inner tube <NUM> and the outer tube <NUM>.

The handle <NUM> further comprises an irrigation duct <NUM> that is fluidly connected to the annulus <NUM> of the delivery tube <NUM>. An irrigation reservoir may be coupled to the irrigation duct <NUM> such that fluid may be circulated via the annulus <NUM> to clear the field of view of the imaging device <NUM> if debris or blood obscures or blocks the field of view of the imaging device. The irrigation duct <NUM> can also be connected to a vacuum such that the annulus <NUM> can be used to drain fluid from the bladder <NUM> and/or urethra to a waste reservoir, not shown.

The handle <NUM> is designed to be operable by the clinician using one hand. Specifically, the handle <NUM> comprises a proximal grip <NUM> and a distal grip <NUM> that are movable longitudinally relative to each other. Moving the proximal grip <NUM> relative to the distal grip <NUM> causes the outer sleeve <NUM> and telescope to move longitudinally relative to the inner tube <NUM>. For this purpose, the proximal grip <NUM> may be connected to the inner tube <NUM> and the distal grip <NUM> may be connected to the outer sleeve <NUM> and telescope through the plug <NUM>. As such, moving the grips <NUM>, <NUM> relative to each other effects relative movement between the inner tube <NUM> and the outer sleeve <NUM> and telescope plug <NUM>.

In this example, the proximal grip <NUM> comprises a thumb ring <NUM> into which the clinician may place a thumb and the distal grip <NUM> comprises a finger loop <NUM> into which the clinician may place their fingers. The finger loop <NUM> allows the clinician to pull the distal grip <NUM> toward the proximal grip <NUM> thereby moving the outer sleeve <NUM> and the telescope plug <NUM> proximally relative to the inner tube <NUM>. This is beneficial as it ensures that the inner tube <NUM> and thus the expander <NUM> is held static with respect to the prostatic urethra <NUM> during deployment and allows the telescope and outer sleeve <NUM> to move together. Also advantageously, the clinician can view and confirm that the apices of the expander <NUM> are positioned correctly relative to the anatomy and therefore can deploy the expander <NUM> in the desired location within the anatomy.

Furthermore, the clinician may operate the proximal and distal grip in reverse, for example by pushing their fingers against the distal side of the finger loop <NUM>, opening the hand span and in turn moving the distal grip <NUM> distally relative to the proximal grip <NUM>. This is beneficial as it allows the clinician to return the outer sleeve <NUM> from the fully-deployed or partially-deployed position to the storage position.

The handle <NUM> further comprises a safety catch or lever <NUM> that may, for example, be located on an upper surface of the distal grip <NUM> or on either side of the distal grip <NUM> or a power grip. The lever <NUM> is operable to prevent or to permit movement of the proximal grip <NUM> and distal grip <NUM> relative to each other longitudinally. The lever <NUM> may, for example, be movable between three distinct detent positions that correspond to the storage, partially-deployed and fully-deployed positions of the outer sleeve <NUM>.

For example, when the lever <NUM> is in the first, storage, position the proximal grip <NUM> and distal grip <NUM> are locked longitudinally relative to each other such that the outer sleeve <NUM> is retained in the storage position as shown in <FIG>. This is beneficial as the clinician may insert the delivery tube <NUM> into the urethra via the penis without a risk of the outer sleeve <NUM> moving to the deployed position and causing the expander <NUM> to be deployed in the incorrect position.

When the distal end region <NUM> of the delivery tube <NUM> has been advanced sufficiently along the urethra, for example to the bladder neck <NUM> or prostatic urethra <NUM>, the clinician may move the lever <NUM> to the partially-deployed position. This unlocks the proximal and distal grips <NUM>, <NUM> so that the clinician may pull the proximal grip <NUM> back relative to the distal grip <NUM> to move the grips <NUM>, <NUM> and hence the outer sleeve <NUM> of the delivery tube <NUM> to the partially-deployed position. At this stage, movement of the proximal grip <NUM> is related to the delivery tube <NUM> such that only a partial length of about <NUM> to <NUM> of the expander <NUM> is uncovered so that the expander <NUM> will not accidentally release and deploy.

<FIG> shows a schematic plan view of the distal end region <NUM> of the delivery tube <NUM> in the partially-deployed position in which the outer sleeve <NUM> has been retracted to partially unsheath the expander <NUM>. When in the partially-deployed position, the distal end of the outer sleeve <NUM> is positioned distally with respect to the retention formations <NUM> but proximally with respect to the distal end <NUM> of the expander <NUM>. As such, the expander <NUM> is partially unsheathed but is still retained on the inner tube <NUM>. From this position, the clinician may operate the handle <NUM> to return the outer sleeve <NUM> to the storage position if it is decided not to complete deployment of the expander <NUM>.

Moving the outer sleeve <NUM> to the partially-deployed position causes the telescope <NUM> to move proximally such that the distal end <NUM> of the expander <NUM> comes within the field of view <NUM> of the telescope <NUM>. It will be apparent that imaging takes place from the inside out, that is, from a viewpoint within the expander <NUM> looking out at the anatomy through at least a distal portion of the expander <NUM>. This effectively juxtaposes the expander <NUM> with the anatomy and therefore provides a reliable reference for the clinician to see and appreciate the angular and longitudinal position of all parts of the expander <NUM> relative to the prostatic urethra <NUM>.

Once the clinician is satisfied that the expander <NUM> is located correctly within the prostatic urethra <NUM>, the lever <NUM> is moved from its partially-deployed position to its fully-deployed position such that the distal grip <NUM> may be moved longitudinally towards the proximal grip <NUM> to its fully-deployed position. This moves the outer sleeve <NUM> and the telescope <NUM> proximally relative to the inner tube <NUM> as shown in <FIG> in which the expander <NUM> and retention formations <NUM> are fully uncovered by the outer sleeve <NUM>. Uncovering the retention formations <NUM> allows the expander <NUM> to disengage the retention formations <NUM> and to expand radially to the deployed position.

The three stages of deployment, namely stowed, partially-deployed and fully-deployed, beneficially allow the clinician to deploy the expander <NUM> in a controlled manner and mitigates the potential for the expander <NUM> to be deployed accidentally or in the wrong location. For example, the lever <NUM> prevents accidental operation of the handle <NUM> that could cause the expander <NUM> to be deployed incorrectly. Furthermore, the inner tube <NUM> may be held static relative to the anatomy during operation of the handle <NUM> as the telescope <NUM> moves inside it, allowing the anatomy to be visualised together with the expander <NUM>. This improves the accuracy of deployment of the expander <NUM> and promotes radial expansion of the expander <NUM> during deployment with minimal longitudinal movement relative to the anatomy.

<FIG> shows an end-on view of the inner tube <NUM> and expander <NUM> in a stored configuration, with the outer sleeve <NUM> removed for clarity. The inner tube <NUM> comprises an imaging device <NUM> such as a telescope or imaging chip located within the inner lumen <NUM>. The imaging device <NUM> shown comprises an electronic imaging chip <NUM>, such as a CMOS chip and at least one light source <NUM> for illuminating the region that is being imaged by the imaging device <NUM>. The light source <NUM> may be, for example, an LED or optical fibre that is configured to illuminate the area to be imaged by the imaging device <NUM>.

The imaging chip <NUM> has a wide field of view, for example <NUM>° or more, such that the clinician may view a large area of the anatomy. As shown in <FIG>, the field of view <NUM> of the imaging device <NUM> extends through the expander <NUM> when the outer sleeve <NUM> is in the storage configuration and the expander <NUM> is retained on the distal end <NUM> portion of the inner tube <NUM>. This is advantageous as it allows the clinician to view the expander <NUM> relative to the anatomy which assists the clinician when positioning the expander <NUM> angularly and longitudinally within the prostatic urethra <NUM>.

As shown in <FIG>, when the outer sleeve <NUM> is in the storage position, the field of view <NUM> of the imaging device <NUM> extends through the outer sleeve <NUM>. However, in <FIG> when in the partially-deployed position, the outer sleeve <NUM> is retracted such that it is no longer in the field of view <NUM> of the imaging device <NUM>. Retracting the outer sleeve <NUM> out of the field of view of the imaging device <NUM> in the partially-deployed position is beneficial as it improves the extent and clarity of the image provided to the clinician. Furthermore, the partially-deployed position allows the distal prongs <NUM> of the expander <NUM> to contact the lobes of the prostate <NUM> such that the clinician may view and fully appreciate the position of the expander <NUM> relative the prostatic urethra <NUM> prior to full deployment. This advantageously enables the clinician to check if the expander <NUM> is positioned correctly prior to full deployment.

To illustrate this, <FIG> is a schematic view of an image captured by the imaging device <NUM> when the outer sleeve <NUM> is in the partially-deployed position. The image of <FIG> shows each of the distal prongs of the expander <NUM> aligned with and contacting the lateral prostatic lobes around the prostatic urethra <NUM>. Specifically, the posterior prong <NUM> of the expander is shown surrounding or straddling the verumontanum <NUM> whereas the two anterior prongs <NUM>, <NUM> of the expander <NUM> are oriented such that they engage the anterior lobes <NUM>.

It will be apparent that the image provided to the clinician by the imaging device <NUM> beneficially allows simultaneous visualisation of the longitudinal position of the expander <NUM> relative to the anatomy, for example the verumontanum <NUM> and the bladder neck <NUM>, and also the angular position of the expander <NUM> relative to the verumontanum <NUM> and the prostatic lobes. This facilitates accurate positioning of the expander <NUM> within the prostatic urethra <NUM>.

Turning now to <FIG>, a flow chart outlining a method of deploying the expander <NUM> within the prostatic urethra <NUM> is shown. In the first step <NUM>, the clinician inserts the delivery tube <NUM> of the delivery device <NUM> into the urethra of the patient via the penis. The delivery tube <NUM> is inserted into the urethra in the storage configuration such that the expander <NUM> is covered by the outer sleeve <NUM>.

The delivery tube <NUM> is advanced along the urethra until the distal end of the delivery tube <NUM> reaches the bladder neck <NUM>. As the delivery tube <NUM> is advanced along the urethra, the clinician may view the anatomical landmarks of the patient, for example the external sphincter <NUM>, the verumontanum <NUM> and the bladder neck <NUM>, from the image captured by the imaging device <NUM>. This is beneficial as it allows the clinician to assess the patient and to check for any structures that may prevent the expander <NUM> being deployed, for example for an obstructing intravesical median lobe.

Next, in Step <NUM>, the clinician reconfigures the delivery device <NUM> from the storage configuration to the partially-deployed configuration. To do so, the clinician moves the lever <NUM> from the stored position to the partially-deployed position and then moves the distal grip <NUM> in a proximal direction to move the outer sleeve <NUM> proximally relative to the expander <NUM> and the inner tube <NUM> such that the expander <NUM> is partially uncovered. This is allows the clinician to view the distal prongs of the expander <NUM> relative to the lateral prostatic lobes around the prostatic urethra <NUM>.

In Step <NUM>, the clinician positions the expander <NUM> at a target site in the prostatic urethra <NUM> by moving the distal end region <NUM> of the delivery tube <NUM> in a proximal direction from the bladder neck <NUM>. As noted with reference to <FIG>, the extent of proximal movement may be judged with the aid of graduation marks on the delivery tube <NUM> to indicate the axial distance travelled from the bladder neck <NUM>. In this way, the bladder neck <NUM> may be used as a datum for positioning the expander <NUM> longitudinally within the prostatic urethra <NUM>.

When the clinician is satisfied that the distal end region <NUM> and thus the expander <NUM> are at the correct longitudinal position, the clinician may then rotate the delivery device <NUM> to orient the expander <NUM> at an appropriate angle within the target site. The expander <NUM> is oriented such that the distal apices <NUM> of the expander <NUM> that are visible in the image captured by the imaging device <NUM> are aligned with the prostatic lobes around the prostatic urethra <NUM>. The clinician may also move the delivery tube <NUM> in a further distal direction when the expander <NUM> is in the correct orientation such that the verumontanum <NUM> comes into view <NUM>. The expander <NUM> can thereby be placed in a clinically-acceptable position between the bladder neck <NUM> and verumontanum <NUM>, with the apices circumferentially targeting the lateral lobes.

If the clinician is satisfied that the expander <NUM> is correctly positioned within the prostatic urethra <NUM> then they may reconfigure the delivery device <NUM> to the fully-deployed configuration in Step <NUM>. Alternatively, if the clinician is not satisfied with the position of the expander <NUM>, the delivery device <NUM> may be returned to the storage configuration and the procedure may be aborted or tried again.

The delivery device <NUM> is moved into the fully-deployed configuration by first moving the lever <NUM> to the fully-deployed position before moving the distal grip <NUM> in a proximal direction. This moves the outer sleeve <NUM> and telescope proximally while keeping the inner tube <NUM> and thus the expander <NUM> static relative to the target site. In a further embodiment, the inner tube <NUM> may be or comprise a camera lumen that moves in the proximal direction while the expander <NUM> is held stationary relative to the target site. This ensures that the expander <NUM> is deployed in the intended position.

When the outer sleeve <NUM> is moved to the fully-deployed position, the proximal apices <NUM> disengage from the retention features <NUM> and expand in an outward radial direction. The walls <NUM>, <NUM> of the slot <NUM> promote radial expansion of the expander <NUM> and minimise longitudinal movement of the expander <NUM> during deployment.

After the expander <NUM> has been deployed, the delivery device <NUM> may be returned to the storage or partially-deployed configuration in Step <NUM>. This is beneficial as the outer sleeve <NUM> then covers the retention formations <NUM> to reduce the risk of the retention formations <NUM> inadvertently re-engaging and moving the expander <NUM> after deployment. The clinician may then view the deployed expander <NUM> through the imaging device <NUM> to check that the expander <NUM> is correctly positioned. When the clinician is satisfied that the expander <NUM> has been deployed correctly the delivery device <NUM> may be withdrawn proximally from the urethra.

Turning now to <FIG>, an embodiment of the delivery device <NUM> is shown in which the delivery tube <NUM> comprises a series of graduation marks <NUM> spaced at known intervals along the length of the delivery tube <NUM> to allow positioning of the expander <NUM>, that is in a fixed position to the delivery tube <NUM> with the bladder neck <NUM>. <FIG> shows a schematic of the inner tube <NUM> comprising an overmoulded hub <NUM> attached to a proximal end of the inner tube <NUM>. The hub <NUM> comprises a boss hole <NUM> for attaching the hub <NUM> to the handle <NUM>. The boss hole feature <NUM> ensures that the position of the inner tube <NUM> relative to the proximal grip <NUM> is maintained.

The graduation marks <NUM> are shown on the inner tube <NUM>. However, the graduation marks <NUM> may be on the inner tube <NUM> or on the outer sleeve <NUM>. The graduation marks <NUM> are visible to the clinician as the delivery tube <NUM> is advanced along the urethra thereby giving the clinician an indication of the longitudinal position of the distal tip <NUM> of the inner tube <NUM> within the urethra.

The skilled reader will understand that the graduation marks <NUM> may be positioned at any known interval suitable for positioning the delivery tube <NUM> longitudinally within the urethra. Furthermore, the graduation marks <NUM> may be numbered. The graduation marks can also be used to approximate the prostatic urethral length during the procedure, which may guide the clinician to select the most clinically acceptable position for the expander <NUM>.

The graduation marks <NUM> may be used when the distal tip <NUM> of the inner tube <NUM> is located at the bladder neck <NUM> before moving the delivery tube <NUM> in a proximal direction. This is beneficial as the clinician may know that, for example, the expander <NUM> should be located two graduation marks proximally from the bladder neck <NUM>. In this instance, when the proximal tip of the delivery tube <NUM> is located at the bladder neck <NUM>, the clinician may then retract the delivery tube <NUM> by two graduation marks <NUM> to position the expander <NUM> at the desired longitudinal position. The clinician can read the graduation marks along the portion of the delivery tube <NUM> within the patient or outside the patient.

A delivery device <NUM> according to a further embodiment is described below with reference to <FIG>. For clarity, reference numerals for comparable features have been kept consistent across the two embodiments.

<FIG> shows a perspective view of the delivery device <NUM> according to the further embodiment. The delivery device <NUM> comprises a handle <NUM> operatively connected to a flexible delivery tube <NUM>. The delivery tube <NUM> is configured to at least partially receive the expander <NUM> in a compressed state and to position and deploy the expander <NUM> within the prostatic urethra <NUM> of a patient. The delivery tube <NUM> is similar to the previous embodiment in that it comprises an inner tube <NUM> surrounded by an outer sleeve <NUM> movable between a storage position, a partially-deployed position and a fully-deployed position. However, the delivery device shown in <FIG> further comprises an intermediate steering tube that surrounds the inner tube <NUM> and is in turn surrounded by the outer sleeve <NUM>. The steering tube is not shown in <FIG> but is described in further detail below.

The flexibility of the delivery tube <NUM> shown in <FIG> is beneficial as the delivery tube <NUM> can bend and flex to conform to the path of the patient's urethra, thereby reducing any discomfort experienced by the patient. The steering tube allows the position and inclination of the distal tip region <NUM> to be controlled and steered, which beneficially assists in the insertion and positioning of the delivery tube <NUM> within the patient. Furthermore, the steerable delivery tube <NUM> allows the imaging device <NUM> of the delivery tube <NUM> to be moved to provide a wider field of view to the clinician.

<FIG> is a perspective view of the distal end region <NUM> of the delivery tube <NUM>. The distal end region <NUM> of the outer sleeve <NUM> has been shown as transparent in <FIG> for clarity. The distal end portion of the outer sleeve <NUM> is suitably of a rigid plastics material so that it can accommodate the outward radial force exerted by the expander <NUM> and keep the expander <NUM> in a stored position within the system. Conversely, the proximal portion of the outer sleeve <NUM> is suitability of a flexible plastics material and may, for example, consist of or comprise a braided sheath. At least a proximal portion of inner tube <NUM> is also of flexible plastics and may also consist of or comprise a braided sheath.

<FIG> shows the steering tube <NUM> surrounding the inner tube <NUM> and surrounded by the outer sleeve <NUM>. The steering tube <NUM> is an elongate flexible plastics tube with a braided distal end <NUM>. The steering tube <NUM> is operable by a clinician via the handle <NUM> to vary the position and inclination of the distal tip region <NUM> and thus the expander <NUM>. Furthermore, in this embodiment, the retention features <NUM> are secured to and extend distally from the braided distal end <NUM>. The retention features <NUM> are configured to engage the expander <NUM> and to prevent longitudinal or circumferential movement of the expander <NUM> relative to the steering tube <NUM>.

The distal end of the steering tube <NUM> is shown schematically in <FIG> with the inner tube <NUM> and the outer sleeve <NUM> removed for clarity. The steering tube <NUM> comprises a steering ring <NUM> at the distal end <NUM> of the braided portion <NUM>. Two steering wires <NUM> are connected to opposing sides of the steering ring <NUM> and extend proximally along the length of the steering tube <NUM> to the handle <NUM>. The steering wires <NUM> are operably coupled to the handle <NUM> whereby a clinician may vary the tension in the steering wires <NUM>. This causes the position and inclination of the steering ring <NUM>, and thus the expander <NUM>, to be controlled by a clinician operating the handle <NUM>.

The flexibility of the proximal portion of the outer sleeve <NUM> and the flexibility of the inner tube <NUM> are such that they can accommodate and allow the deflected angle of the steering tube <NUM> without kinking or increasing the deflection force required by the steering wires <NUM>.

The steering tube <NUM> further comprises two retention formations <NUM> for retaining the expander <NUM> in the delivery tube <NUM>. The retention formations <NUM> are elongate tabs that extend distally from the distal end <NUM> of the braided portion <NUM> such that the retention formations <NUM> protrude from the end of the steering tube <NUM>. The retention formations <NUM> each comprise a retention slot <NUM> for retaining the expander <NUM> and are spaced angularly about the steering tube <NUM> such that the expander <NUM> is oriented to align with the prostatic lobes when the delivery tube <NUM> is inserted into the prostatic urethra <NUM>.

As shown in <FIG>, the retention formations <NUM> each comprise a proximal protrusion <NUM> and a distal protrusion <NUM> with a retention slot <NUM> defined between them. The retention slot <NUM> is configured to at least partially receive a proximal end <NUM> of the expander <NUM>, thereby inhibiting longitudinal or circumferential movement of the expander <NUM> relative to the inner tube <NUM>. When the outer sleeve <NUM> surrounds the retention formations <NUM>, for example in the storage or partially-deployed configuration, the outer sleeve <NUM> surrounds the retention formations <NUM> and prevents the expander <NUM> from expanding radially and hence disengaging the retention formations <NUM>.

The inner tube <NUM> is movable longitudinally relative to the steering tube <NUM> between a distal position as shown in <FIG> and a proximally retracted position. When in the retracted position, the distal tip <NUM> of the inner tube <NUM> is located between the proximal end <NUM> and the distal end <NUM> of the expander <NUM>. Moving the inner tube <NUM> between the distal position and the retracted position beneficially changes the longitudinal position of the imaging chip <NUM> relative to the expander <NUM>. Specifically, when the inner tube <NUM> is in the distal position, the imaging chip <NUM> is positioned distally of the distal end <NUM> of the expander <NUM> such that expander is not within the field of view of the imaging chip <NUM>. Conversely, when the inner tube <NUM> is in the retracted position, the distal end of the expander <NUM> is within the field of view of the imaging chip <NUM>. This beneficially allows the distal end <NUM> of the expander <NUM> to be imaged relative to the anatomy within the prostatic urethra <NUM>.

As shown in <FIG>, the inner tube <NUM> comprises two grooves <NUM> extending longitudinally in a proximal direction from the distal tip <NUM> of the inner tube <NUM>. The grooves <NUM> are configured to at least partially receive the retention formations <NUM>. This is advantageous as the grooves <NUM> accommodate some of the thickness of the retention formations <NUM> and so reduce the overall diameter of the delivery tube <NUM>.

Furthermore, the grooves <NUM> allow and guide movement of the inner tube <NUM> relative to the steering tube <NUM> between the distal position and the retracted position.

<FIG> is a schematic view of one embodiment of the distal end region <NUM> of the delivery tube <NUM> in the storage configuration. When in the storage configuration, the inner tube <NUM> is in the distal position and the outer sleeve <NUM> is in the storage position surrounding the expander <NUM>. The distal tip <NUM> of the inner tube <NUM> extends distally with respect to the distal end of the outer sleeve <NUM> when the inner tube <NUM> is in the distal position. This beneficially allows the imaging chip <NUM> to capture images of the anatomy that are not obscured by the expander <NUM> or the outer sleeve <NUM>.

Furthermore, the distal end portion of the inner tube <NUM> is of rigid plastics to support the expander <NUM> along its length when the inner tube <NUM> is in the distal position. When the delivery tube <NUM> is being inserted into, and along, the urethra, the inner tube <NUM> thereby prevents the expander <NUM> deflecting inwardly which could otherwise cause the expander <NUM> to disengage from the retention formations <NUM> prematurely.

Turning now to <FIG>, the delivery tube <NUM> is shown here in the partially-deployed configuration. In the partially-deployed configuration, both the inner tube <NUM> and the outer sleeve <NUM> have been moved proximally relative to the expander <NUM> such that the distal end <NUM> of the expander is now unsheathed. Furthermore, the inner tube <NUM> is in the retracted position such that the distal tip <NUM> of the inner tube <NUM> is located at a longitudinal position between the proximal and distal ends of the expander <NUM>. As shown in <FIG>, when the delivery tube <NUM> is in the partially-deployed configuration, the distal end of the outer sleeve <NUM> is located proximally relative to the distal tip <NUM> of the inner tube <NUM> and distally relative to the retention formations <NUM>. The outer sleeve <NUM> therefore retains the expander <NUM> in the stored configuration whilst not obscuring the field of view of the imaging chip <NUM>.

<FIG> is a schematic view of the distal end region <NUM> of the delivery tube <NUM> in the fully-deployed configuration. In the fully-deployed configuration, the outer sleeve <NUM> is moved proximally to the extent that its distal end is located proximally with respect to the retention features <NUM>. This fully uncovers the expander <NUM> and allows the expander <NUM> to expand radially, thereby to disengage from the retention formations <NUM>.

Turning now to <FIG>, this shows a perspective view of the handle <NUM>. The handle <NUM> comprises three buttons 230a, 230b, 230c that are operable by the clinician to reconfigure the delivery tube <NUM> between the storage, partially-deployed and fully-deployed configurations as outlined in <FIG>. The buttons 230a, 230b, 230c allow the clinician to adjust the delivery tube <NUM> easily between the various configurations. The handle <NUM> further comprises a lever <NUM> that is connected to the steering wires <NUM>. The lever <NUM> may be operated to vary the tension in the wires and thus to control the position and inclination of the distal end of the steering tube <NUM>.

The handle <NUM> may further comprise a lever or button that can lock the delivery tube <NUM> in a desired configuration. This prevents the clinician inadvertently reconfiguring the delivery tube <NUM> to the partially-deployed or fully deployed configuration before the expander <NUM> is positioned correctly in the patient's anatomy.

The handle <NUM> of <FIG> further comprises an irrigation tube <NUM>, also shown in <FIG>.

<FIG> shows an alternative embodiment of the steering tube <NUM>. In <FIG>, the retention features <NUM> extend from the distal end <NUM> of the steering tube <NUM>, for example being connected to, and extending distally from, the steering ring <NUM>. Each retention feature <NUM> comprises a distal protrusion <NUM>. In this example, the retention slot <NUM> is defined between the distal protrusion <NUM> and the distal end <NUM> of the braided portion <NUM> of the steering tube <NUM>. The expander <NUM> may be at least partially received within the retention slot <NUM> as before.

<FIG> shows a further embodiment of the steering tube <NUM>. In <FIG>, the retention features <NUM> extend from the distal end of the steering tube <NUM> as described above in relation to <FIG>. However, in this case the retention features <NUM> are attached to and extend from a retaining ring <NUM>. The retention features <NUM> and the retaining ring <NUM> may form a discrete sub-assembly that can be coupled to the steering ring <NUM> of the steering tube <NUM>.

Turning now to <FIG>, a flow chart outlining a method of deploying the expandable implant <NUM> within the prostatic urethra <NUM> is shown. In the first Step <NUM>, the delivery tube <NUM> of the delivery device <NUM> is inserted into the patient's urethra via the penis. The delivery tube <NUM> is inserted in the storage configuration in which the outer sleeve <NUM> surrounds the expander <NUM> thereby retaining the expander <NUM> in the stored configuration. The clinician may operate the handle <NUM> to control the steering ring <NUM> and adjust the angle of the distal tip region <NUM> of the delivery tube <NUM> to aid insertion of the delivery tube <NUM> into and along the urethra.

The distal end of the delivery tube <NUM> is advanced along the urethra until it reaches the bladder neck <NUM>. In Step <NUM>, the delivery tube <NUM> is reconfigured from the storage configuration to a partially-deployed configuration. In the partially-deployed configuration, the inner tube <NUM> is retracted so that the imaging chip <NUM> at the distal end of the inner tube <NUM> may view the distal end <NUM> of the expander <NUM>. Furthermore, the outer sleeve <NUM> is also retracted such that the distal end <NUM> of the expander <NUM> is unsheathed but the proximal end <NUM> of the expander <NUM> remains sheathed and retained on the retention formations <NUM>.

In Step <NUM> the clinician positions the expander <NUM> at a target site in the prostatic urethra <NUM> by moving the distal end region <NUM> of the delivery tube <NUM> in a proximal direction from the bladder neck <NUM> with the aid of graduation marks on the delivery tube <NUM> to indicate the axial distance travelled from the bladder neck <NUM>. The bladder neck <NUM> may thereby be used as a datum for positioning the expander <NUM> longitudinally within the prostatic urethra <NUM>. When satisfied that the distal end region <NUM> and thus the expander <NUM> are in the correct longitudinal position, the clinician may then rotate the delivery device <NUM> to orient the expander <NUM> at the target site. The expander <NUM> is oriented such that the distal apices <NUM> of the expander <NUM> that are visible on the image captured by the imaging device <NUM> are aligned with the prostatic lobes around the prostatic urethra <NUM>.

As before, the clinician may move the delivery tube <NUM> further in a distal direction when the expander <NUM> is in the correct orientation so that the verumontanum <NUM> comes into view. The expander <NUM> can thereby be placed in a clinically-acceptable position between the bladder neck <NUM> and verumontanum <NUM>, with the apices circumferentially targeting the lateral lobes.

In Step <NUM>, when the clinician is satisfied with the position of the expander <NUM>, the outer sleeve <NUM> is retracted to the fully-deployed position such that the expander <NUM> is deployed within the prostatic urethra <NUM>. Finally, in Step <NUM>, the delivery tube <NUM> is removed from the urethra. The delivery tube <NUM> may be withdrawn in the fully-deployed configuration or preferably the clinician reconfigures the delivery tube <NUM> to the partially-deployed or storage configurations. In all configurations, but most effectively in the storage configuration, the clinician may use the imaging chip <NUM> to view the deployed expander <NUM> to confirm that the expander <NUM> has been deployed correctly within the prostatic urethra <NUM>.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application as defined in the claims. For example, the intermediate tube <NUM> to which the expander <NUM> is directly or indirectly fixed need not necessarily have steering functionality.

Turning finally to <FIG>, these drawings show further details of a practical embodiment of the invention.

<FIG> shows three elongate elements of a delivery sheath forming part of a delivery system of the invention. These three elongate elements of the delivery system are concentrically-aligned sheaths, namely: an innermost imaging sheath <NUM> with a rigid camera tip <NUM> that exemplifies an imaging head, an inner or intermediate steering sheath <NUM> surrounding the imaging sheath <NUM>; and an outer sheath <NUM> surrounding the imaging sheath <NUM> and the steering sheath <NUM>. All of the sheaths <NUM>, <NUM>, <NUM> are tubular in this example although, in principle, the imaging sheath <NUM> could be a solid but flexible rod with any wiring, cabling or ducting for the camera tip <NUM> embedded within it, for example in respective parallel channels of an extruded profile. In any event, any such wires or cables must be isolated from each other and from any flow of irrigating liquid that is conveyed along the imaging sheath <NUM>.

The sheaths <NUM>, <NUM>, <NUM> must be as thin as possible to ensure that the overall diameter of the delivery sheath assembly is advantageously small, for example with an outer diameter of less than sixteen French (<NUM>) in the application described. As a non-limiting illustrative example, the outer sheath <NUM> may have a wall thickness of about <NUM> whereas the main proximal section of the steering sheath <NUM> may have a wall thickness of about <NUM>, allowing about <NUM> for the expander <NUM> and for clearance. The wall thickness of the imaging sheath <NUM> under the expander <NUM> may, for example, be about <NUM>.

The sheaths <NUM>, <NUM>, <NUM> are flexible enough to permit an angle of deflection of, say, <NUM> to <NUM> degrees so as to accommodate the curvature of the male urethral anatomy and to access the prostatic urethra. In particular, the sheaths <NUM>, <NUM>, <NUM> must be capable of flexing along their length as they extend along the male urethra from the point of insertion at the penile meatus through to the bladder neck. The sheaths <NUM>, <NUM>, <NUM> therefore each have a flexible steering section to provide for deflection driven by a steering mechanism controlled by a handle (not shown) at the proximal end of the delivery sheath. The sheaths <NUM>, <NUM>, <NUM> also each have a flexible proximal section to provide for deflection imposed by the anatomy, for example to track through the curvature of the penile canal. For example, one or more of the sheaths <NUM>, <NUM>, <NUM> may be braided for flexibility to accommodate curvature of the anatomy and deflection of the imaging tip, but the structure must also be stiff enough axially and circumferentially to resist the forces of insertion, steering, navigation, unsheathing of the expander <NUM> and, if necessary, re-sheathing of the expander <NUM>. As explained below, any or all of the sheaths <NUM>, <NUM>, <NUM> may have tailored stiffness and flexion properties for these purposes.

The torsional stiffness of the sheaths <NUM>, <NUM>, <NUM> must be sufficient to allow for angular alignment of the expander <NUM> about the longitudinal axis. In this respect, the circumferential or angular positioning of the expander <NUM> is controlled by global rotation of the handle. The handle thereby applies torque to the sheaths <NUM>, <NUM>, <NUM> attached to it, noting that the sheaths <NUM>, <NUM>, <NUM> are fixed against circumferential angular movement relative to the handle and so cannot rotate independently of the handle.

Each sheath <NUM>, <NUM>, <NUM> has a hub <NUM> on its proximal end, shown here only on the imaging sheath <NUM> and the steering sheath <NUM>, that allows the sheath to slot into a specific axial position in the handle. The hubs <NUM> lock the respective sheaths <NUM>, <NUM>, <NUM> within the system in such a way that prevents them from moving in any direction except axially along a fixed travel path, as controlled by a clinician operating the handle.

The simplest and most basic form of sheath would be a single extrusion comprising a polymer material of a certain durometer value. However, a single material extrusion with the necessarily thin wall thickness may present a technical challenge as it could kink or buckle when deflected by a steering mechanism, or under axial compression, or under other bending loads. For this reason, any or all of the sheaths <NUM>, <NUM>, <NUM> may benefit from differential material properties along their length to provide the individual sheaths, and the stacked sheath assembly, with the design characteristics required to access the prostatic urethra, to navigate the anatomy, and to steer and support the expander <NUM>.

Examples of characterisation properties to be tailored along the length of a sheath <NUM>, <NUM>, <NUM> may include: flexibility; kink resistance; trackability; the ability to apply axial force parallel to the longitudinal axis - i.e. 'pushability'; and the ability to apply torque about the longitudinal axis - i.e. 'torquability'. Tailoring may, for example, be achieved by the following options:.

<FIG> is a series of views showing components of a distal end portion <NUM> of the delivery sheath of <FIG> as a stack-up assembly, working radially outwardly in sequence from the inside out.

<FIG> shows the braided imaging sheath <NUM> with the rigid camera tip <NUM>. The camera tip <NUM> has image-sensing and lighting features like those shown in <FIG>, in addition to an irrigation channel or duct that extends along the imaging sheath <NUM> and terminates at the distal tip. The irrigation duct may be fluidly connected to a Luer connector on the handle whereby liquid can travel down the imaging sheath <NUM> from the proximal end.

<FIG> shows the steering sheath <NUM> that lies on and surrounds the imaging sheath <NUM> and terminates at the proximal end of the distal end portion <NUM>, hence being spaced from the distal tip to leave a distally-protruding portion of the imaging sheath <NUM> exposed.

<FIG> shows a pull ring <NUM> added to the distal end of the steering sheath <NUM> and <FIG> shows an implant holder <NUM> added to the distal end of the steering sheath <NUM> around the pull ring <NUM>. The pull ring <NUM> and the implant holder <NUM> lie at the interface between the imaging sheath <NUM> and the steering sheath <NUM> and permit longitudinal movement of the imaging sheath <NUM> relative to the steering sheath <NUM>. In particular, the imaging sheath <NUM> slides longitudinally within and with respect to the steering sheath <NUM>, the pull ring <NUM> and the implant holder <NUM>.

The pull ring <NUM> and the implant holder <NUM> will be described in more detail with reference to <FIG>. For now, it will be noted that the proximal end portion of the implant holder <NUM> is radially oversized relative to the diameter of the steering sheath <NUM>, thus defining a cylindrical bearing surface <NUM> that stands proud of the steering sheath <NUM>. It will also be noted that the implant holder <NUM> has a longitudinally-stepped profile such that its distal end portion is narrower than its proximal end portion, defining a distal support surface <NUM> from which a pair of lugs serving as retention formations <NUM> project radially as described previously.

<FIG> shows an implant in the form of an expander <NUM> now added to surround the exposed portion of the imaging sheath <NUM> that protrudes distally from the steering sheath <NUM>. The thickness of the wire of the expander <NUM> is less than the step change in the diameter of the implant holder <NUM> between the bearing surface <NUM> and the support surface <NUM>. The expander <NUM> extends from a proximal end where it is supported by the support surface <NUM> of the implant holder <NUM> to a distal end where it is supported by the camera tip <NUM>. The expander <NUM> is held against axial and circumferential movement relative to the steering sheath <NUM> by the retention formations <NUM>.

<FIG> shows the outer sheath <NUM> now added to surround all of the aforementioned components. The outer sheath <NUM> is shown here advanced distally relative to the steering sheath <NUM> and the expander <NUM> into the storage position that retains and enshrouds the expander <NUM>. Despite being thin-walled, the outer sheath <NUM> must constrain the crimped expander <NUM> without deforming excessively. Optionally, therefore, the outer sheath <NUM> could have a relatively rigid section at its distal tip to constrain the crimped expander <NUM>, adjoining a relatively flexible proximal section forming most of the length of the outer sheath <NUM>.

It will be apparent that longitudinal sliding movement of the outer sheath <NUM> relative to the steering sheath <NUM> is guided and facilitated by sliding on the bearing surface <NUM> of the implant holder <NUM>. This minimises the area of sliding contact, and hence friction, and maintains concentricity between the sheaths <NUM>, <NUM>, <NUM>.

In this example, the distal extremity of the camera tip <NUM> with its image-capturing and lighting components, such as a CMOS chip and LEDs adjacent an irrigation duct, protrudes distally from the distal end of the outer sheath <NUM>. This ensures the best possible field of view as the delivery sheath navigates the anatomy before deployment of the expander <NUM>. However, in other examples, the distal extremity of the camera tip <NUM> could be substantially level with the distal end of the outer sheath <NUM> or could even be recessed proximally to a small extent.

The various views of <FIG> show the distal end portion <NUM> of the delivery sheath and illustrate variants in the length of the rigid camera tip <NUM>, parallel to the longitudinal axis of the delivery sheath.

<FIG> show a short camera tip <NUM> as also shown in the views of <FIG>, in the storage and partially-deployed configurations respectively. Correspondingly, the camera tip <NUM> is shown in advanced and retracted positions in <FIG> respectively. In this example, the length of the camera tip <NUM> is about one quarter of the overall length of the expander <NUM>. A correspondingly long portion of the more flexible imaging sheath <NUM> is exposed beyond the distal end of the steering sheath <NUM> and underlies the expander <NUM>.

<FIG> shows how, in the partially-deployed configuration, the outer sheath <NUM> and the imaging sheath <NUM>, including the camera tip <NUM>, are pulled back proximally relative to the steering sheath <NUM> and hence also relative to the expander <NUM>. Thus, beneficially, the image capture device of the camera tip <NUM> when in the retracted position can visualise the expander <NUM> against a backdrop of the adjacent anatomy, from a viewpoint within the expander <NUM>.

<FIG> show longer camera tips <NUM> than that shown in <FIG>, both views being of the distal end portion <NUM> in the storage configuration in which the expander <NUM> is covered fully by the outer sleeve <NUM>. In <FIG>, the length of the camera tip <NUM> is about half of the overall length of the expander <NUM>. A correspondingly shorter portion of the imaging sheath <NUM> is exposed beyond the distal end of the steering sheath <NUM>. In <FIG>, the camera tip <NUM> extends substantially the entire length of the expander <NUM>. In that case, none of the imaging sheath <NUM> is exposed beyond the distal end of the steering sheath <NUM>.

Thus, by varying the length of the camera tip <NUM> relative to the more flexible imaging sheath <NUM>, the support that underlies the expander <NUM> can be tailored to have differential stiffness along its length. This may, for example, help to accommodate movement of the imaging sheath <NUM> through the deflected steering sheath <NUM>, noting that the imaging sheath <NUM> must move within the deflected section of the steering sheath <NUM> that surrounds it and so must be flexible enough to accommodate its deflected curvature. Conversely, during re-sheathing, the distal end of the camera tip <NUM> must be pushed back to its start position through the distal apices of the expander <NUM> to return to the distal tip of the delivery sheath. The camera tip <NUM> must be supported securely enough to undergo this distal movement without deflection or buckling of the structure that supports the camera tip <NUM>.

Potentially, the stiffness of the imaging sheath <NUM> can be tailored to vary along its length - for example, with tailored braiding comprising braided elements of varying density, pitch, angle and/or thickness - so as to provide stable support for the expander <NUM> and yet to navigate easily around the deflected steering sheath <NUM>.

The various views in <FIG> show the assembly of the pull ring <NUM> and the implant holder <NUM> in more detail. As best seen in <FIG>, a circumferential step <NUM> effects the aforementioned change in external diameter between the bearing surface <NUM> and the support surface <NUM> of the implant holder <NUM>. <FIG> shows that the height or radial protrusion of the retention formations <NUM> is the same as, or slightly less than, the height of the step <NUM>.

Each retention formation <NUM> is spaced distally from the step <NUM> to define a gap or slot <NUM> that can accommodate a respective proximal apex of the expander <NUM> held by the outer sleeve <NUM> (not shown) against the support surface <NUM>. The step <NUM> therefore serves as a proximal retention formation that cooperates with each retention formation <NUM>.

Internally, as best seen in the longitudinal sectional views of <FIG>, the implant holder <NUM> has a circumferential shoulder <NUM> that effects a step change in the diameter of its longitudinal lumen from a narrow distal portion <NUM> to a wider proximal portion <NUM>. The internal diameter of the distal portion <NUM> is a sliding fit with the external diameter of the imaging sheath <NUM> (not shown).

The proximal portion <NUM> of the implant holder <NUM> accommodates the pull ring <NUM> as an interference fit. The pull ring <NUM> could also, or alternatively, be secured in the implant holder <NUM> by a bonding process suitable for polymers such as reflow or over moulding. Adhesives and curing could also be used. The distal end of the pull ring <NUM> abuts the proximally-facing shoulder <NUM>. The proximal end of the pull ring <NUM> lies distally with respect to the proximal end of the implant holder <NUM>. <FIG> shows that a narrowed distal end portion of the steering sheath <NUM> is received and anchored within the pull ring <NUM>. The internal diameter of the steering sheath <NUM> substantially matches that of the distal portion <NUM> of the implant holder <NUM> and so is also a sliding fit with the external diameter of the imaging sheath <NUM>.

As shown in <FIG> and also in <FIG>, the pull ring <NUM> has a circumferential array of angularly-spaced holes <NUM> to facilitate joining the steering ring to the implant holder though a bonding process and two longitudinal slots <NUM> (only one of which is shown) positioned on diametrically-opposed sides of the pull ring <NUM> for anchoring steering wires, not shown.

Thus, this example has an implant holding and steering feature that not only holds the expander <NUM> but can also steer the expander <NUM> and therefore the sheath that supports the expander <NUM>, in this example the innermost imaging sheath <NUM> with its camera tip <NUM>. In this respect, it is advantageous to steer from behind the expander <NUM>, i.e. at a position that is proximal relative to the expander <NUM>, so as to guide the expander <NUM> forward through the anatomy to the deployment location.

In proximal succession from the expander <NUM>, therefore, the steering sheath <NUM> fitted with the pull ring <NUM> and the implant holder <NUM> provides: holding features that hold and orient the expander <NUM>; a steering mechanism acting on a flexible steering section; and a flexible proximal section to track through the penile canal. In conjunction with the imaging sheath <NUM> and the outer sheath <NUM>, the structure of the steering sheath <NUM> must provide sufficient tensile or axial strength for unsheathing and re-sheathing the expander <NUM> and to allow for deflection of the expander. The structure of the steering sheath <NUM> must also provide sufficient torsional strength for orienting the expander <NUM> angularly.

In the example shown, the implant holding feature is a moulded component that accommodates a pull ring for steering, being a separate component. However, in another embodiment, the implant holding feature and a pull ring or other steering formation could instead be integrated into one component.

Finally, <FIG> shows, schematically, how an interlock mechanism can control relative axial movement of the sheaths <NUM>, <NUM>, <NUM> in some embodiments. In this example, that relative movement is permitted and controlled by a control element such as a pin <NUM> that can move along a path defined in this example by a slot <NUM>, for example as the slot <NUM> moves relative to the pin <NUM>. The slot <NUM> may, for example, be defined by the distal grip <NUM> of the handle <NUM>, to which the imaging sleeve <NUM> and the outer sleeve <NUM> may be fixed, whereas the distal grip <NUM> may, for example, move relative to the steering sleeve <NUM> and to the pin <NUM> fixed to the steering sleeve <NUM>.

The slot <NUM> is shaped to interact with the pin <NUM>, defining a detent position that prevents longitudinal movement of the pin <NUM> and limited detent ranges within which longitudinal movement of the pin <NUM> is restricted. Movement of the pin <NUM> out of the detent positions or between and beyond those ranges is enabled only by deliberate relative angular movement between the pin <NUM> and the slot <NUM> about a longitudinal axis, for example by articulating a toggle in the handle <NUM>. More generally, the imaging and outer sheaths <NUM>, <NUM> can only move with articulation of components of the handle <NUM> which allow those sheaths <NUM>, <NUM> to move through pre-calculated distances, respectively within and over the steering sheath <NUM>, all in concentric relation.

In this example, the detent position is defined by a laterally-offset notch <NUM> at one end of the slot <NUM>. The detent ranges are defined by a first section <NUM> of the slot <NUM> in series with a second section <NUM> of the slot <NUM>. The second section <NUM> is offset laterally from the first section <NUM> by a laterally-extending kink or chicane <NUM> in the slot <NUM>.

In a start position shown in <FIG>, the pin <NUM> is received in the notch <NUM> that prevents longitudinal movement of the pin <NUM> along the slot <NUM>. This prevents the distal grip <NUM> being moved toward the proximal grip <NUM> of the handle <NUM> and so locks the outer sleeve <NUM> in its distally-advanced storage position that secures the expander <NUM> against inadvertent deployment.

Moving the pin <NUM> laterally out of the notch <NUM> as shown in <FIG> allows the pin <NUM> to enter and move along the first section <NUM> of the slot <NUM>, enabling the distal grip <NUM> to be pulled toward the proximal grip <NUM> in a first stage of movement. The pin <NUM> can move longitudinally along the first section <NUM> to an extent limited by the chicane <NUM>, as shown in <FIG>. In doing so, the outer sheath <NUM> and the imaging sheath <NUM> move proximally by a fixed axial distance toward the handle <NUM>, into the partially-deployed position.

The outer sheath <NUM> and the imaging sheath <NUM> move together proximally and travel the same longitudinal distance relative to the steering sheath <NUM>, which remains fixed against longitudinal movement relative to the handle <NUM>. As described previously, this movement at least partially uncovers the expander <NUM> and allows the expander <NUM> to be imaged from the inside out, with the anatomy also in view.

Moving the pin <NUM> laterally through the chicane <NUM> as shown in <FIG> frees the pin <NUM> from the first section <NUM> of the slot <NUM> and allows the pin <NUM> to enter the second section <NUM> of the slot <NUM>. The pin <NUM> can now move along the second section <NUM>, enabling the distal grip <NUM> to be pulled further toward the proximal grip <NUM> in a second stage of movement. Longitudinal movement of the pin <NUM> along the second section <NUM> continues until the pin <NUM> encounters the opposite end of the second section <NUM>, as shown in <FIG>. By this stage, the outer sheath <NUM> has moved proximally by a further fixed distance into the fully-deployed position in which the expander <NUM> is uncovered completely, released from the system and therefore deployed.

Advantageously, resistance to lateral movement of the pin <NUM> must be overcome before the pin <NUM> can enter the notch <NUM>, or exit the notch <NUM> into the first section <NUM> of the slot <NUM>, or travel in either direction across the chicane <NUM> between the first and second sections <NUM>, <NUM> of the slot <NUM>. This helps to prevent inadvertent movement and provides touch feedback to the clinician to confirm the position of the pin <NUM> relative to the various parts of the slot <NUM>.

Claim 1:
A delivery device (<NUM>) for deploying a self-expanding implant (<NUM>) within a body cavity, the device (<NUM>) comprising:
at least one retention formation (<NUM>) for holding the implant (<NUM>) against axial or circumferential movement;
an elongate longitudinally-extending outer element (<NUM>, <NUM>), radially outboard of the or each retention formation (<NUM>);
an imaging head (<NUM>, <NUM>) disposed on a longitudinal axis that extends on a radially-inboard side of the or each retention formation (<NUM>); and
a handle (<NUM>) connected to a proximal end of the outer element (<NUM>, <NUM>), the or each retention formation (<NUM>) being fixed axially relative to the handle (<NUM>), and the outer element (<NUM>, <NUM>) and the imaging head (<NUM>, <NUM>) being movable axially relative to the handle (<NUM>);
wherein the outer element (<NUM>, <NUM>) is movable bidirectionally in longitudinal directions relative to the handle (<NUM>) between:
a storage position in which the outer element (<NUM>, <NUM>) surrounds the implant (<NUM>) and holds the implant (<NUM>) engaged with the or each retention formation (<NUM>); and
a partial-deployment position in which the outer element (<NUM>, <NUM>) uncovers a distal portion of the implant (<NUM>) while surrounding a proximal portion of the implant (<NUM>) to continue holding the implant (<NUM>) engaged with the or each retention formation (<NUM>);
and the imaging head (<NUM>, <NUM>) is retractable in a proximal direction relative to the handle (<NUM>) from:
an advanced position when the outer element (<NUM>, <NUM>) is in the storage position; to
a retracted position when the outer element (<NUM>, <NUM>) is in the partial-deployment position.