Vascular graft

An endoprosthetic device comprises a tubular main body having a length including proximal and distal portions, the tubular main body having a flexible portion between the proximal and distal portions, and at least one adjustable length docking branch extending laterally from the tubular main body, and having sections bearing a tab or loop graspable by a user, and optionally further having at least one auxiliary branch, and at least one access branch, for assembly with at least one tubular branch body having a laterally extending access branch, using a delivery system including a delivery shaft, and a retrieval capsule and corresponding press-fit retrieval pin and retrieval wire, wherein the delivery shaft is provided with a pivotal slotted housing serving as a user handle for the delivery shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase filing under 35 U.S.C. § 371 of International Application PCT/GB2017/052916, filed Sep. 28, 2017, and published as WO 2018/060716 on Apr. 5, 2018. PCT/GB2017/052916 claims priority from United Kingdom application number 1616722.3, filed Sep. 30, 2016. The entire contents of each of these prior applications are hereby incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to surgical procedures and provides a prosthetic device for use as a hybrid endograft in a patient requiring surgery, particularly an intervention to treat a vascular pathology.

BACKGROUND OF THE INVENTION

Parts of the vascular system may develop degenerative defects over time, and one such defect is an aneurysm. An aneurysm is an abnormal bulge in the wall of a blood vessel leading to a localised weakening of the blood vessel wall with an increased potential for leakage, rupture and internal bleeding. The aneurysm may cause significant dilation of the natural (native) lumen of the blood vessel compromising natural blood flow. The present disclosure relates to an endograft suitable for insertion into the aneurysm sac in the defective blood vessel to restore the vessel lumen dimensions to those of the natural blood vessel before the aneurysm developed and thereby occlude the aneurysm sac. The disclosed device is suitable for endoluminal treatment of the aortic arch including the ascending and descending aorta and branch arteries; left subclavian artery, left common carotid artery, brachiocephalic artery, right common carotid artery.

Conventional methods for treatment of weakened portions of the vasculature include surgical replacement of the affected portion of the aorta, or a more conservative, minimally invasive endovascular repair.

In surgical intervention, the affected part of the blood vessel can be excised and replaced with a prosthetic graft. This invasive approach is normally performed under general anaesthesia with cardiopulmonary by-pass, so that the patient's thorax can be opened and the prosthesis sutured in place of the aneurysmal vessel. Consequently, the method requires the time of a skilled surgeon and prolonged recovery periods for the patient in hospital. Prosthetic grafts normally used for such replacement are typically made from polyester fabric, which may be woven or knitted, and may be sealed with a sealant, for example gelatine or collagen.

The endovascular repair techniques use endoprosthetic devices which are placed within the patient using bespoke delivery systems designed to deliver the endoprosthetic device in a compact “packaged” form for intraluminal delivery, and including removable restraining means, allowing the endoprosthetic device to be delivered, positioned, and finally selectively deployed. When the endoprosthetic device is deployed, the delivery system is removed, allowing the surgical procedure to be completed.

Hybrid procedures combine a conventional or modified surgical procedure with an endovascular intervention procedure and are feasible in selected high surgical risk patients. For example use of hybrid procedures provides an alternative to open repair in high risk surgical patients with complex aortic pathology. A vascular endoprosthesis apt to exclude an aneurysmal portion of the aorta is disclosed in U.S. Pat. No. 8,740,971 B2 the content of which is incorporated herein by reference.

Whereas there is a continuing need to improve surgical procedures and endoprosthetic devices suitable for addressing patient needs, endoprosthetic devices and methods disclosed herein offer the ability to create an arterial anastomosis with reduced risk of detrimental tension whilst having sufficient scope for manoeuvre during the procedure.

Additionally, the endoprosthetic devices and methods disclosed herein permit blood flow sooner than before, with the ability to expel air from an endoprosthetic device by displacement through a valve feature of blood flow into the endoprosthetic device.

SUMMARY OF THE INVENTION

Using the hybrid endoprosthetic devices disclosed herein in a known procedure or in a procedure modified as disclosed herein permits rapid perfusion of aortic arch branch arteries by anti-grade blood flow whereby subsequent steps required to complete a procedure can be conducted thereafter at an acceptable pace with a foreseeable reduction in risk of ischemia or related problems normally associated with the known procedures. Therefore, the usual time pressure to complete the procedure is somewhat lessened. Significantly, the procedures described in this disclosure are designed to be carried out whilst the patient's heart remains beating, i.e. the patient is not supported on a “heart-lung” machine and so the procedure is classed as an “off-pump” procedure which offers numerous advantages. Nevertheless it is not exclusively restricted to “off-pump” procedures and can be usefully employed due to time savings in “on-pump” procedures where the patient is supported on a “heart-lung” machine.

The term “aortic arch branch arteries” is generally understood to encompass the left subclavian artery, left common carotid artery, right common carotid artery and brachiocephalic artery. Connection of these arteries to an endoprosthetic device is provided for in the following disclosure using newly conceived devices and modifications thereof to be more particularly described herein.

Broadly this disclosure relates to an endoprosthetic device useful in a hybrid surgical procedure, that serves as a substitute for a deteriorated or injured part of a natural vessel, and is configured for flow connection with adjacent natural vessels normally communicating with the deteriorated or injured part of a natural vessel. In particular embodiments, the endoprosthetic device may substitute part of the aortic arch region of the vasculature, and has lateral branches for connection with aortic arch branch vessels. According to aspects to be more particularly described herein below, a device enabling early perfusion in a procedure is disclosed.

According to an aspect, an endoprosthetic device comprises a tubular main body having a length including proximal and distal portions, the tubular main body having a flexible portion between the proximal and distal portions, and is provided with at least one adjustable length docking branch extending laterally from the tubular main body. In embodiments, the endoprosthetic device has at least one access branch. Such an access branch may be positioned on the tubular main body and configured to permit access to a docking branch. Such an access branch may be useful for delivery of a modular component through the docking branch.

In embodiments at least one of the proximal and distal portions of the tubular main body includes a stent.

In embodiments the proximal and distal portions of the tubular main body each include a stent.

Provision of an adjustable length docking branch addresses the frequent problem of anatomical variance in the vasculature of patients.

In embodiments the adjustable length docking branch comprises a crimped fabric sleeve over at least a portion of its adjustable length, enabling the docking branch to be stretched lengthwise, and when required curved in a desired direction.

In embodiments, the crimped fabric comprises expanded polytetrafluoroethylene (ePTFE) or polyester.

The term “crimped” as used in the present disclosure relates to a fabric profile having a circumferential corrugation or spiral profile which when viewed from a side has a generally zig-zag outline or sinusoidal profile wherein the exterior surface undulates from a maximum dimension to a minimum dimension repeatedly over a substantial length of the docking branch. Such a crimped profile permits additional length for the docking branch to be obtained by applying a longitudinal stretch. Alternatively a reduced length can be obtained by applying a longitudinal compression. Additionally the crimp surface also accommodates bending of the docking branch to accommodate re-direction of the docking branch from straight profile to a curved profile which may be required for connection with a native vessel and to account for vascular variance in patients.

In embodiments, the adjustable length docking branch has a length comprising a series of sections, each section having a tab which may be gripped to facilitate trimming of the length of the docking branch.

In embodiments each section has a holding loop instead of a tab which improves the ability to grasp and hold the docking branch for trimming under the slippery conditions of the surgical procedure due to the presence of body fluids.

The tab or loop can be made of a biocompatible material such as a polyester fabric, polyethylene or ePTFE.

In embodiments, the endoprosthetic device is provided with at least one auxiliary branch extending from the tubular main body. The auxiliary branch may be used for a variety of tasks, for example perfusion of the endoprosthetic device, insertion and removal of a surgical tool, or for delivery or removal of components of another device or components of a delivery system.

In embodiments, the, or each auxiliary branch may include an integrated valve to enable at least one of air removal, flushing and perfusion.

According to another aspect a vascular graft is provided as a modular assembly comprising at least one additional component for use with the endoprosthetic device disclosed herein wherein the additional component comprises a tubular branch body having a length including proximal and distal stented portions, the tubular branch body having a flexible portion between the proximal and distal stented portions, and is configured to connect with a docking branch of the endoprosthetic device to form a vascular graft modular assembly.

The tubular branch body may have a laterally extending access branch for a delivery system component or device.

A plurality of such modular components may be provided for attachment respectively to multiple docking branches of the tubular main body.

The provision of a plurality of modular components addresses the problems associated with use of pre-formed one piece multi-branch endoprosthetic devices. Therefore a more flexible and versatile endoprosthetic device is available to the surgeon.

The endoprosthetic device may comprise a modular assembly of a tubular main body and a plurality of tubular branch bodies selected from a kit of modular components comprising a tubular main body, and a plurality of tubular branch bodies wherein the plurality of tubular branch bodies may include tubular branch bodies of the same or differing dimensions to anticipate anatomical variance. For example the tubular branch bodies may be of differing lengths. Optionally the tubular branch bodies may have a tapered length portion.

Whereas endovascular procedures typically involve delivery of endoprosthetic devices in a compact form for expansion within a natural vessel lumen, by use of balloon expansion or by use of compressed resilient stents, the embodiments of the present modular assembly usefully employ multiple stented sections within the proximal and distal portions of the tubular main body and of the or each tubular branch body to facilitate rapid circumferential anastomoses. This feature, in the anticipated procedure in most cases, obviates the need to fully suture the junction of the parts connected by the stented portion.

The endoprosthetic device offers procedural advantages as a modular assembly of the tubular main body and plurality of tubular branch bodies by virtue of enabling a staged (sequential) deployment following insertion through a natural vessel side wall. The compact nature of the modular parts offers a low size profile during the staged deployment procedure. This facilitates the provision of substantially continuous blood flow and provides an ability to reduce ischemia time period.

Furthermore, the staged (sequential) insertion and deployment that is made possible by use of a modular assembly of the tubular main body and plurality of tubular branch bodies also allows the surgical procedure to proceed without the need for a full thoracotomy, avoiding generally the need to place the patient on a heart lung machine. Thereby, the normal risks of induced hypothermia and cardiac arrest associated with a major surgical opening of the chest cavity are also mitigated.

The disclosed modular assembly provides a sealed system that can minimise blood loss and maintain blood perfusion during the surgical procedure.

The modular assembly may mimic the structure of a natural main vessel and associated branch vessel(s).

According to another aspect a delivery system for the vascular graft modular assembly including the endoprosthetic device comprises a sheath for confining a tubular branch body in a compact form for delivery through a lumen, a retrieval capsule and a press-fit retrieval pin configured to fit within the retrieval capsule, and a retrieval wire having a proximal end and a distal end, wherein one of the retrieval capsule and a press-fit retrieval pin is attached to the sheath and the other is attached to the distal end of the retrieval wire, the proximal end of the retrieval wire being available to a user of the system.

In an embodiment, the press-fit retrieval pin may be attached to the sheath whilst the retrieval capsule is attached to the retrieval wire.

In an embodiment, the press-fit retrieval pin has a head portion of a shape enabling it to be captured within a corresponding recess in the retrieval capsule. The shape may be a ball, bullet or arrowhead and the head portion may be made from a resilient material allowing a degree of compression of the head portion during press-fitting into the retrieval capsule and elastic expansion of the head portion when the head portion is located in the corresponding recess in the retrieval capsule.

The retrieval capsule may be part of a retrieval capsule assembly having an external wall configured to form a sealing close fit within a docking branch so as to serve as a movable hemostat within the docking branch so as to minimise blood loss prior to connection of the tubular branch body to the docking branch by deployment of a stented portion of the tubular branch body therein.

In use of such an embodiment for an endoprosthetic device having a tubular main body with at least one docking branch extending laterally from the tubular main body, a user presents a tubular branch body having stented portions in a compact form within a sheath, and having a press-fit retrieval pin attached to the sheath, in juxtaposition with a retrieval capsule with attached retrieval wire previously passed through the tubular main body via an access or auxiliary branch, the retrieval pin is press-fitted into the retrieval capsule, the tubular branch body is then insertable into a docking branch of the main body of the endoprosthetic device, and by pulling upon the retrieval wire, the tubular branch body is first positioned in the docking branch of the main body of the endoprosthetic device and thereafter the stented portions of the tubular branch body may be deployed by removal of the sheath via the access or auxiliary branch.

The manner of removal of the sheath is not limited, and for that purpose a pull strap, pull wire, or pull cord can be used to initiate removal. The sheath may be designed to facilitate removal by having tearable parts, for example a lengthwise axial tear line which can be torn by contact with a pull wire to part the sheath lengthwise. Alternatively, the delivery system may incorporate a slitting tool and the sheath may be designed to split (tear) in a predictable and controllable manner under application of appropriately applied force when in contact with the slitting tool.

The sheath may comprise a smooth polymeric material. A polymerised hydrofluorocarbon such as PTFE is suitable. Alternatively the sheath may be formed from polyethyleneterephthalate (PET). The selected material should be one which is biocompatible and may be readily passed through natural vessels or artificial lumens without sticking. The sheath may be surface treated, for example to impart or enhance hydrophilic properties by applying a hydrophilic coating.

Suitable polymeric flexible materials for the sheath may be selected from thermoplastic polymers, elastomers, and copolymers such as nylon, polyurethane, polyethylene (PE), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), fluorinated ethylene propylene, polyether block amides (PEBA), polyimide, polyether ether ketone, and polybutylene terephthalate.

The sheath may be of a multi-layered construction of flexible, polymeric materials, such as multi-layered extrusions, optionally reinforced as by use of braided layered assemblies or laminar structures incorporating bonding layers and reinforcements, or intermittent extruded composite extrusions and assemblies of variable durometer characteristics.

According to another aspect a valve and air venting capability is introduced into an auxiliary or access branch of the main tubular body by provision of at least a removable valve and an integral valve deliverable upon a delivery shaft.

The removable valve may comprise a C-clamp portion of a pivotal slotted housing mounted upon the delivery shaft, the C-clamp portion being configured to clamp over a fabric tubular body positioned upon the delivery shaft.

The valve and air venting capability may comprise a slotted housing configured around a delivery shaft upon which a device may be mounted and constrained in a compact form within a removable sheath, the slotted housing forming a removable C-shape clamp valve part about the delivery shaft and compact endoprosthetic device positioned upon the delivery shaft. The housing may be pivotally mounted upon the delivery shaft to allow the C-shape clamp valve part to be removed from gripping about the delivery shaft and endoprosthetic device during or after deployment of the endoprosthetic device by removal of the sheath. The pivotal mounting for the housing may be located and spaced distally on the delivery shaft with respect to the position of the C-shape valve part. The housing may also enclose an integral valve and vent positioned upon the delivery shaft, which integral valve and vent may be resident within the access branch of the device after removal of the delivery shaft, and removed subsequently in the procedure when the access branch is to be cut down and sutured closed, the integral valve and vent being removable with the cut off access branch fabric to be disposed of.

The housing may be configured to serve as a user handle for manipulation and control of the delivery system.

The handle may have an internal chamber within which an integral valve deliverable upon the delivery shaft can be positioned for delivery purposes.

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIG. 1, there is shown an endoprosthetic device1. The endoprosthetic device1comprises a tubular main body3having a length including proximal11and distal portions13, the tubular main body having a flexible portion between the proximal11and distal portions13, and is provided with at least one adjustable length docking branch5extending laterally from the tubular main body3.

In embodiments, the endoprosthetic device1has at least one access branch7. Such an access branch7may be positioned on the tubular main body3and configured to permit access to a docking branch5. Such an access branch7may be useful for delivery of a modular component through the docking branch5.

In embodiments at least one of the proximal11and distal portions13of the tubular main body includes a stent15.

In embodiments the adjustable length docking branch5comprises a crimped fabric sleeve enabling the docking branch5to be stretched lengthwise, and when required curved in a desired direction.

In embodiments, the adjustable length docking branch5has a length comprising a series of sections, each section having a tab which may be gripped to facilitate trimming of the length of the docking branch5. However, in the depicted example, each section has a holding loop17instead of a tab which improves the ability to grasp and hold the docking branch5for trimming under the slippery conditions of the surgical procedure due to the presence of body fluids. The tab or loop17can be made of a biocompatible material such as a polyester fabric.

In embodiments, the endoprosthetic device1is provided with at least one auxiliary branch7extending from the tubular main body3. The auxiliary branch7may be used for a variety of tasks, for example perfusion of the endoprosthetic device1, insertion and removal of a surgical tool, or for delivery or removal of components of another device or components of a delivery system.

In embodiments, the, or each auxiliary branch7may include an integrated valve to enable air removal and system flushing.

The device1is also provided with main body access branches9which extend from the main tubular body3.

With reference toFIG. 2, there is shown an example delivery system21for the device1. The system21includes main tubular body sheaths23for confining

proximal11and distal portions13portions of the tubular main body3upon a delivery shaft. Each sheath23is attached to a capsule support holder29, and is provided with a splitter25and a handle27for a surgeon to grip. Each delivery shaft has a tip24to facilitate insertion and passage thereof through a lumen.

The delivery system21also includes a modular component delivery system, which shall be described in more detail below. InFIG. 2, a first portion of the modular component delivery system31is depicted attached to the access branch7, and comprises a branch valve33.

With reference toFIG. 3, there is shown a modular component35for use with the endoprosthetic device1disclosed herein. The component35comprises a tubular branch body36having a length including proximal and distal stented portions39,41. With reference toFIGS. 1 and 3, the tubular branch body36has a flexible portion between the proximal and distal stented portions39,41, and is configured to connect with a docking branch5of the endoprosthetic device1to form a modular assembly.

The tubular branch body36may have a laterally extending access branch37for a delivery system component or device. A plurality of such modular components35may be provided for attachment respectively to multiple docking branches5of the tubular main body3.

The endoprosthetic device1may comprise a modular assembly of a tubular main body3and a plurality of tubular branch bodies selected from a kit of modular components comprising a tubular main body3, and a plurality of tubular branch bodies wherein the plurality of tubular branch bodies may include tubular branch bodies of the same or differing dimensions to anticipate anatomical variance. For example the tubular branch bodies may be of differing lengths. Optionally the tubular branch bodies may be tapered.

With reference toFIG. 4, (and in part toFIG. 3for device parts), there is shown a second portion of the modular component delivery system43. The modular component delivery system comprises a sheath47for confining a tubular branch body having proximal41and distal39portions in a compact form for delivery through a lumen. A press-fit retrieval pin57configured to fit within a separate retrieval capsule (not shown), attachable to a retrieval wire (not shown) is shown protruding from a compact (sheathed) tubular branch55. In the depicted example, the modular component delivery system is shown to include a sheath47confining a compacted tubular branch body36(FIG. 3) of a modular component35, and a valve45. The example sheath47compacts the tubular branch proximal portion upon a delivery shaft of which a tip49is visible, a hub51including a sheath splitter and a sheath pull handle53for releasing the tubular branch body36from the sheath47.

The sheath47may comprise a smooth polymeric material. A polymerised hydrofluorocarbon such as PTFE is also suitable to form the sheath47from. Alternatively the sheath47may be formed from polyethyleneterephthalate (PET). The selected material should be one which is biocompatible and may be readily passed through natural vessels or artificial lumens without sticking. The sheath47may be surface treated, for example to impart or enhance hydrophilic properties by applying a hydrophilic coating. Suitable polymeric flexible materials for the sheath47may be selected from thermoplastic polymers, elastomers, and copolymers such as nylon, polyurethane, polyethylene (PE), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), fluorinated ethylene propylene, polyether block amides (PEBA), polyimide, polyether ether ketone, and polybutylene terephthalate.

The sheath47may be of a multi-layered construction of flexible, polymeric materials, such as multi-layered extrusions, optionally reinforced as by use of braided layered assemblies or laminar structures incorporating bonding layers and reinforcements, or intermittent extruded composite extrusions and assemblies of variable durometer characteristics.

In an embodiment, the press-fit retrieval pin57may be attached to the sheath47whilst the retrieval capsule is attached to the retrieval wire.

In an embodiment, the press-fit retrieval pin57has a head portion of a shape enabling it to be captured within a corresponding recess in the retrieval capsule. The shape may be a ball, bullet or arrowhead and the head portion may be made from a resilient material allowing a degree of compression of the head portion during press-fitting into the retrieval capsule and elastic expansion of the head portion when the head portion is located in the corresponding recess in the retrieval capsule.

With reference toFIGS. 5 to 11, an example of how the endoprosthetic device1may be used to repair a damaged aortic arch59will now be described. First and second purse string sutures surrounded incisions71,73are made in the aortic arch59in two positions to facilitate endovascular insertion of both the proximal and stented portions of the endoprosthetic device1into ascending61and descending aorta portions63of the aortic arch59.

Third and fourth purse string sutures surrounding incisions75,77are also made into the side walls of major vessels which typically extend from the top of the aortic arch59e.g. the Left Sub-Clavian Artery (LSA)69, Left Common Carotid Artery (LCCA)67and Right Common Carotid Artery (RCCA)). In the depicted example, the third incision75is made in the LCCA67and the fourth incision77is made in the LSA69.

The third and fourth incisions75,77facilitate endovascular connections to these vessels by means of modular components35delivered in a similar way to the endoprosthetic device1. These modular components35connect the major vessels to the device1, to ensure that the blood supply is maintained to a cerebral region and upper limbs of a patient.

Compacted distal and proximal sections are each held inside a main tubular body sheath of the endoprosthetic device1are inserted through their respective purse string surrounded incisions71,73.

While in the compacted state the distal and proximal sections enable blood perfusion through the arch59to be maintained. This can be done off-pump, which requires haemostasis across the junction between the sheath and incision to be maintained and this can be controlled through tension applied across a purse string suture, both before and after the unsheathing of the distal and proximal sections.

The distal and proximal sections of the device1are unsheathed in rapid succession, therefore enabling blood flow to be maintained through the aortic arch. This results in the damaged aortic arch sac59being bi-passed through the device1. A mid-section of the device1is outside of the arch59while the proximal and distal sections are within the damaged arch59.

Furthermore the major branch vessels (LSA, LCCA, RCCA) at this stage are now without blood perfusion. To prevent ischemia, these are quickly re-instated and this is facilitated by the provision of modular branch components35a,35b.

A purse string suture and the modular component35aare inserted through the third incision. The purse string tension is then adjusted to ensure haemostasis (to prevent blood loss between the outside of the sheath and the incision).

The other end of the modular component35ais then inserted into the docking branch5of the device1. The retrieval capsule sheath on the end of the modular component35is then clipped into the retrieval capsule within the device1.

The sheath and retrieval capsule can then be withdrawn through the auxiliary branch7. Just prior to this step it is intended to vent air and blood through the branch valve.

The sheath82is removed from the modular component35a, fully deploying it so it opens up within the docking branch7. This essentially connects the main device1to the native vessel, the LSA69in this example, so that blood supply and perfusion is therefore re-established. The intention is that this is performed quickly and efficiently to ensure that ischemia is minimised.

The docking branch5is provided with holding loops17to help locate, hold and stabilise the docking branch when connecting the modular device35b. The docking branch5is also trim-able to facilitate anatomical variances without compromising their function.

In the depicted example, a second modular component35bis then inserted into another docking branch5of the device1(there may be 1, 2, 3 or more docking branches, however only2are shown inFIGS. 10 and 11), and used connect the main device1to the native vessel in the same way as modular component35adescribed above.

The modular branch delivery system withdraws the sheath through the auxiliary branch7of the device1, which towards the end of the procedure is dissected and removed from the device1. The auxiliary branch7may then be cut from the device1.

With blood flowing through the device1and the LCCA and LSA, a surgeon can then transect a main trunk of the damaged aorta arch59, with the main device placed into the cavity of the native arch vessel.

With reference toFIGS. 12 to 16, how the branch modular component delivery system31is used in practice will now be described. In use of such an embodiment for an endoprosthetic device1having a tubular main body3with at least one docking branch5extending laterally from the tubular main body3, a user presents a tubular branch body36having stented portions in a compact form within a sheath47, and having a press-fit retrieval pin57attached to the sheath, in juxtaposition with a retrieval capsule81with attached retrieval wire83previously passed through the tubular main body3via an access or auxiliary branch5, the retrieval pin57is press-fitted into the retrieval capsule81, the tubular branch body36is then insertable into a docking branch5of the main body3of the endoprosthetic device1, and by pulling upon the retrieval wire83, the tubular branch body36is first positioned in the docking branch of the main body of the endoprosthetic device and thereafter the stented portions of the tubular branch body is deployed by removal of the sheath47via the access or auxiliary branch.

The manner of removal of the sheath47is not limited, and for that purpose a pull strap, pull wire, or pull cord can be used to initiate removal. The sheath47may be designed to facilitate removal by having tearable parts, for example a lengthwise axial tear line which can be torn by contact with a pull wire to part the sheath lengthwise. Alternatively, the delivery system may incorporate a slitting tool and the sheath47may be designed to split (tear) in a predictable and controllable manner under application of appropriately applied force when in contact with the slitting tool.

FIGS. 12 to 16show sequential steps of the connection of the modular branch component35to the main body component3and the same reference numerals are used to identify the same parts as used above throughout the sequence.

With reference toFIG. 16, there is shown in detail three sequential stages of the connection of a retrieval capsule81and the retrieval pin57. In the depicted example, the shape of the head portion of the retrieval pin57is shown to be that of an arrowhead. In the first stage of the connection process, the head portion is aligned with the retrieval capsule81. In the second stage of the process, the head portion is press-fitted within the retrieval capsule81. When the head portion is press-fitted inside the retrieval capsule81it undergoes a degree of compression to allow it to enter the retrieval capsule81and then undergoes a degree of elastic expansion to retain it inside the retrieval capsule81.

With reference toFIG. 17, there is shown as an example adjustable length docking branches5for the endoprosthetic device1. Each adjustable length docking branch is shown to extend laterally from the tubular main body3, and to comprise a crimped fabric sleeve enabling the docking branch5to be stretched along its length and when required curved in a desired direction. In the depicted example, the adjustable length docking branch5has a length comprising a series of sections and each section is provided with a holding loop17.

FIG. 18shows the capability of the docking branch5to adjust in length when a stretch is applied to the docking branch5.

As shown inFIG. 19, in use, the surgeon may initially stretch the docking branch5so that it increases in length and then shorten the branch5to the desired length by cutting the branch5with a cutting tool. The docking branches5then return to an unstretched configuration.

With reference toFIGS. 20 to 33, a valve and air venting capability99is introduced into an auxiliary or access branch7of the main tubular body3by provision of at least a removable valve113and an integral valve/vent115deliverable upon a delivery shaft103. The valve and air venting capability99may comprise a slotted housing101configured around a delivery shaft103upon which a device1may be mounted and constrained in a compact form within a removable sheath23, the slotted housing101forming a removable C-shape clamp valve part105about the delivery shaft103and compact endoprosthetic device1positioned upon the delivery shaft103. The housing may be pivotally mounted upon the delivery shaft103to allow the C-shape clamp valve part105to be removed from gripping about the delivery shaft103and endoprosthetic device1during or after deployment of the endoprosthetic device1by removal of the sheath23. The pivotal mounting109for the housing101may be located and spaced distally on the delivery shaft103with respect to the position of the C-shape valve part105. The housing101may include a chamber for enclosing the integral valve and vent positioned upon the delivery shaft103, which integral valve/vent115may be resident within the access branch of the device1after removal of the delivery shaft103, and removed subsequently in the procedure when the access branch is to be cut down and sutured closed, the integral valve115and vent being removable with the cut off access branch fabric to be disposed of.

The housing101may be configured to serve as a user handle for manipulation and control of the delivery system21.

NUMERALS USED IN THE DRAWINGS (FOR REFERENCE ONLY)