ENDOLUMINAL DELIVERY ASSEMBLY

Description Technical Field

This invention relates to a delivery or deployment assembly for intraluminal or endovascular delivery of a stent graft. Background of the Invention The preferred embodiments are discussed generally with respect to the deployment of a stent graft into the thoracic aorta but the teachings herein are not so limited and may, for example, apply to deployment into other body lumens. It is important when delivering a stent graft by intraluminal or endovascular methods to know exactly where the device is in the vasculature, particularly in relation to branch vessels which could be adversely occluded by placement of the stent graft. To avoid occlusion there have been proposed fenestrations along the length of a stent graft and scalloping at the proximal and distal ends of the stent graft to allow flow from a main vessel to a branch vessel through the fenestration or scallop. The use of radio opaque markers around the periphery of the fenestration or scallop in this regard has been proposed. However, this method has not always proven most certain or reliable in terms of placement.

Particularly, when deploying into a curved vessel it is known that a deployment device will take up a position in the vessel on the outside or greater radius side of the curved vessel. This can cause problems in that the bending of the stent graft is not necessarily accurately known, making it difficult to achieve its precise placement.

It is known to retain the proximal and distal ends of a stent graft onto a deployment device to facilitate relative longitudinal and rotational movement of the ends. However, owing to the tortuosity of vessels through which a deployment device must be progressed and the rotation necessary to achieve progression, the final rotational position of a stent graft may not be fully known.

As a result, it can be difficult to ensure correct placement and orientation of a stent graft in such circumstances. Summary of the Invention

The present invention seeks to provide improved delivery of endovascular devices, in particular improved delivery of stent grafts.

The preferred embodiment seeks to provide a retention mechanism for a stent graft onto a deployment device for more accurate deployment of the stent graft therefrom or to at least provide a practitioner with a useful alternative. According to an aspect of the present invention, there is provided an endovascular delivery assembly as specified in claim 1 .

According to another aspect of the present invention, there is provided a stent graft delivery system as specified in claim 12.

In the preferred embodiment, the system provides for the stent graft to be retained onto the deployment device so that a fenestration or scallop on the stent graft is in a selected position with respect to a portion of the deployment device when it is curved, thereby providing for more accurate.

As a particular example, the aorta of a patient comprises an ascending aorta from the aortic heart valve, a thoracic arch and a descending aorta. Major branch vessels extend from the thoracic arch. Occlusion of one or more of these upon placement of a stent graft in the thoracic arch could have serious consequences. The major vessels generally extend from the outside or greater radius side of the curved thoracic arch. Thus, a stent graft retained onto a deployment device such that a scallop on the stent graft is on the outside of the deployment device when it is curved, as provided by the system taught herein, can ensure more correct and reliable placement.

Throughout this specification the term "distal" with respect to a portion of the aorta, a deployment device or a stent graft is intended to mean the portion of the aorta, deployment device or stent graft further away in the direction of blood flow from the heart and the term "proximal" is intended to mean the portion of the aorta, deployment device or end of the stent graft nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be

understood.

In the preferred embodiment, the pusher catheter comprises a longitudinal lumen therethrough, the guide wire catheter extending through the longitudinal lumen so that the guide wire catheter is movable longitudinally and rotationally with respect to the pusher catheter.

There may also be included a flexible sheath over the pusher catheter and extending to the nose cone dilator, thereby to retain the stent graft in a contracted conformation on the guide wire catheter.

The releasable fastening can comprise a release wire system to releasably retain the stent graft to the guide wire catheter.

The release wire system used to retain releasably the stent graft to the guide wire catheter can comprise a wire wound around the guide wire catheter and through the material of the stent graft in a spiral manner, the wire extending to the distal handle. The pitch of the spiral wound wire can be between 20 to 40 mm.

In another embodiment, there may be provided a plurality of suture loops fastened to the stent graft tubular body and around the guide wire catheter, being looped around the release wire. Thereby, when the release wire is withdrawn the suture loops are released to release the stent graft from the guide wire catheter. The release wire may be stitched or looped in and out of the material of the stent graft along the length of the stent graft.

There can further be a releasable retention system for a proximal end of the stent graft and a releasable retention system for a distal end of the stent graft.

The guide wire catheter can have a pre-formed curve just distal of the nose cone dilator to assist with the deployment device fitting into the thoracic arch.

The flexible sheath can also have a pre-formed curve at its proximal end again to assist with the deployment device fitting into the thoracic arch.

According to another aspect of the present invention, there is provided, a stent graft delivery system in which a stent graft is retained on the delivery system such that a longitudinal portion of the stent graft is releasably retained on the delivery device to bend therewith.

In a preferred embodiment there is provided an endovascular delivery device and a stent graft mounted thereon; the delivery device comprising a pusher catheter, a distal handle on the pusher catheter, a proximal nose cone dilator, a guide wire catheter extending from the pusher catheter to and through the nose cone dilator and a flexible sheath over the pusher catheter and extending to the nose cone dilator and thereby retaining the stent graft in a contracted conformation on the guide wire catheter; the stent graft comprising a tubular body of a biocompatible material with a lumen therethrough and a plurality of stents, the stent graft being mounted onto the delivery device for deployment therefrom and being positioned on the guide wire catheter distally of the nose cone dilator and proximally of the pusher catheter and the guide wire catheter passing through the lumen of the stent graft; a release wire system to releasably retain the stent graft to the guide wire catheter, the release wire system including a release wire wound around the guide wire catheter and through the material of the stent graft in a spiral manner along at least part of the length of the stent graft and the release wire extending to a release mechanism on the distal handle to enable withdrawal of the release wire whereby the stent graft is temporarily affixed to the guide wire catheter and curves with curvature of the guide wire catheter in use and whereby when the release wire is withdrawn the stent graft is released from the guide wire catheter.

According to another embodiment, there is provided an endovascular delivery device and a stent graft mounted thereon; the delivery device comprising a pusher catheter, a distal handle on the pusher catheter, a proximal nose cone dilator, a guide wire catheter extending from the pusher catheter to and through the nose cone dilator and a flexible sheath over the pusher catheter and extending to the nose cone dilator and thereby retaining the stent graft in a contracted conformation on the guide wire catheter; the stent graft comprising a tubular body of a biocompatible material with a lumen therethrough and a plurality of stents, the stent graft being mounted onto

the delivery device for deployment therefrom and being positioned on the guide wire catheter distally of the nose cone dilator and proximally of the pusher catheter and the guide wire catheter passing through the lumen of the stent graft; a release wire system to releasably retain the stent graft to the guide wire catheter, the release wire system including a release wire stitched along at least part of the length of the stent graft and a plurality of suture loops fastened to the tubular body of the stent graft and looped around the guide wire catheter and the stitches of the release wire and the release wire extending to a release mechanism on the distal handle to enable withdrawal of the release wire whereby the stent graft is temporarily affixed to the guide wire catheter and curves with curvature of the guide wire catheter in use and whereby when the release wire is withdrawn the stent graft is released from the guide wire catheter. Brief Description of the Drawing

Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 depicts a introducer or delivery device according to one embodiment of the present invention;

Figure 2 depicts the introducer or delivery device of Figure 1 with the sheath withdrawn to show the components underneath it; Figures 3A and 3B show transverse and longitudinal partial cross-sectional views of a stent graft mounted onto a guide wire catheter of a deployment device according to one embodiment of the present invention;

Figures 4A and 4B show transverse and longitudinal partial cross-sectional views of a stent graft mounted onto a guide wire catheter of a deployment device according to an another embodiment of the present invention;

Figure 5 shows a perspective view of the embodiment shown in Figures 3A and 3B;

Figure 6 shows a perspective view of the embodiment shown in Figures 4A and 4B; Figure 7 shows a schematic view of an aorta of a patient with a deployment device and stent graft according to an embodiment of the present

invention deployed therein;

Figure 8 shows another embodiment of introducer or delivery device according to the present invention; and

Figure 9 shows the embodiment of Figure 8 with the sheath withdrawn to show the components underneath it. Detailed Description

Figures 1 , 2 and 3A and 3B depict a delivery device 2 according to one embodiment of the invention. The delivery device 2 has a guide wire catheter 3 which extends from a distal handle 7 to a proximal tapered nose cone dilator 1 1 longitudinally through a passageway or lumen 5 of a delivery catheter 4 which is connected to the handle 7 at its distal end. An introducer sheath 10 fits coaxially around the delivery catheter 4 and extends from a tapered proximal end 13 which optionally includes a radio opaque marker to a connector valve and manipulator 14 attached about distal end 1 5 of the sheath. The introducer sheath 10 extends proximally to the nose cone dilator 1 1 and covers the stent graft 6 during introduction of the deployment device into a patient and is withdrawn distally to expose the stent graft 6 during deployment when the deployment device is in a selected position within the vasculature of a patient.

The stent graft or implantable device 6 is carried on the guide wire catheter 3 proximally of the delivery catheter 4 and distally of the nose cone dilator 1 1 . Connector valve 14 includes a silicone disk (not shown) for preventing the backflow of fluids therethrough. The disk includes a slit for the insertion of the nose cone dilator 1 1 and delivery catheter 4. Connector 14 also includes side arm 16 to which a tube 17 is connected for introducing and aspirating fluids therethrough. Nose cone dilator 1 1 includes a tapered proximal end 19 for accessing and dilating a vascular access site over a well-known and commercially available wire guide (not shown).

The wire guide is inserted in the vessel with an introducer needle using, for example, the well-known percutaneous vascular access Seldinger technique. A well-known male Luer lock connector hub 20 is attached at the distal end of the guide wire catheter 3 for connection to syringes and other medical apparatus.

The handle 7 at the distal end of the pusher catheter 4 remains outside a patient in use and carries the trigger wire release handle mechanisms 8, 9 and 12 used to release the various portions of the stent graft. The proximal end the stent graft 6 is retained on the delivery device by the use of trigger wires (not shown) connected to the release handle 9, the distal end of the stent graft is retained on the delivery device by the use of trigger wires (not shown) connected to the release handle 8. The handle also includes a release mechanism 12 for a release wire for the longitudinal portion of the stent graft according to the present invention as is discussed below. The stent graft 6 comprises a tubular body 22 of a biocompatible material and a plurality of self expanding stents (not shown for clarity).

A release wire 20 extends from the release mechanism 12 on the handle 7 through the lumen 5 in the delivery catheter 4 and exits at the proximal end of the delivery catheter 4, as shown in Figure 2. The release wire 20 is then wound around the guide wire catheter 3 and through the material of the tubular body 22 in a spiral fashion so that there are lengths 24 of release wire 20 outside the tubular body and turns 26 of release wire 20 around the guide wire catheter 3, as can be particularly seen in Figures 3A, 3B and Figure 5. This arrangement holds the guide wire catheter 3 against a selected longitudinal portion of the stent graft. When the stent graft is deployed into the vasculature of a patient and the device is deployed into a curved vessel, the guide wire catheter of the deployment device will normally take up a position in the greater radius side of the curve owing to its relative rigidity. Hence, the longitudinal portion of the stent graft which is releasably bound to the guide wire catheter will also take up a position at the greater radius side of the curve. This means that a stent graft with a fenestration or scallop which is to be deployed on the greater radius side of the curve can be mounted onto the deployment device with the fenestration or scallop adjacent the guide wire. Once deployed the scallop or fenestration will be easier to position correctly.

When it is desired to release the stent graft, the release wire 20 can be withdrawn by removal of the release wire mechanism 12, which will release the stent graft from its engagement with the guide wire catheter.

In this embodiment the order of placement of the release handle mechanisms 8, 9 and 12 on the handle of the introducer is such that the order of release is first the proximal end of the stent graft, then the distal end of the stent graft and subsequently the longitudinal portion. In other embodiments and assemblies the order of placement may be different. For instance it may be desirable to release first the proximal end, then the longitudinal portion and subsequently the distal end.

Another embodiment is shown in Figures 4A, 4B and Figure 6. In this embodiment the release wire 30 is stitched through the material of the tubular body 22 along the longitudinal portion of the stent graft which is to be placed into a curved vessel at the greater radius side of the curve. This leaves portions 32 of the release wire 20 outside of the tubular body 22 and loops 34 of the release wire 20 inside the tubular body 22. Loops of biocompatible thread 36, such as suture material, are then sewn into the graft material to pass around the guide wire catheter 3 and around the trigger wire loops 34. This arrangement holds the guide wire catheter against a selected longitudinal portion of the stent graft. When the stent graft is deployed into the vasculature of a patient and the device is deployed into a curved vessel, the guide wire catheter of the deployment device will normally take up a position in the greater radius side of the curve. Hence, the longitudinal portion of the stent graft which is releasably bound to the guide wire catheter will also take up a position at the greater radius side of the curve. This means that a stent graft with a fenestration or scallop which is to be deployed on the greater radius side of the curve can be mounted onto the deployment device with the fenestration or scallop adjacent the guide wire. Once deployed the scallop or fenestration will be easier to position correctly.

When it is desired to release the stent graft, the release wire 30 can be withdrawn, which will release each of the loops 36 and hence the stent graft from its engagement with the guide wire catheter. The loops 36 remain sewn into the

wall of the graft material and will not cause a problem in the blood stream. Figures 5 and 6 show these two embodiments when the guide wire catheter is curved, such as when it is placed into a curved vessel such as the thoracic of a patient. It will be noted that the stent graft 6 when not constrained by the sheath 10 has a longitudinal portion retained against the guide wire catheter 3 and otherwise extends out to one side of the guide wire catheter. The stent graft has a scallop 6a at its proximal end and the scallop is aligned with the guide wire catheter. When the guide wire catheter 3 is bent the longitudinal portion of the stent graft with a scallop 6a is deployed on the greater radius side of the curve.

If by suitable imaging techniques the great vessel, such as the left subclavian artery, is seen to be off-centre at the top of the curve of the thoracic arch then the stent graft can be mounted onto the deployment device with its scallop similarly off-centre from the longitudinal portion aligned with the guide wire catheter of the deployment device.

Figure 7 shows a cross-sectional view of a thoracic aorta. It can be seen that the thoracic aorta 40 comprises an ascending aorta 41 which receives blood from the heart though an aortic valve 42. At the upper end of the ascending aorta there are branches for the great vessels, the innominate artery 43, the left common carotid artery 44 and the left subclavian artery 45. The aorta after these great vessels is referred to as the descending aorta 46 and it is in this region that a thoracic aortic aneurysm 47 can occur. In a thoracic aortic aneurysm part of the wall 48 of the descending aorta swells and can burst, with serious consequences. The dotted line 48a shows what would be the normal curved wall of the descending aorta.

As shown in Figure 7 a deployment device 50 has been deployed up through the descending aorta over a guide wire 52. The proximal end of the deployment device extends over the thoracic arch 54 and into the ascending aorta 41 . The sheath 56 has been withdrawn to release partially the stent graft 58 but it is still retained by the release wire 60 onto the guide wire catheter 62 of the deployment device 50. The release wire 60 is wound in a spiral fashion around

the guide wire catheter 62 and through the material of the stent graft 58. It can be noted that, as the thoracic arch is curved, the guide wire catheter of the deployment device has taken up a position on the greater radius side of the curve and hence the longitudinal portion of the stent graft which is releasably bound to the guide wire catheter has also taken up a position at the greater radius side of the curve. This enables the scallop 64 at the proximal end of the stent graft 58, which is positioned adjacent the guide wire catheter 3, to be adjacent the left subclavian artery 45 so that the stent graft does not occlude that artery. At the stage shown both the proximal and distal ends of the stent graft have been released but, as discussed above, the distal end may be retained and not released until the longitudinal portion retention has been released.

Withdrawal of the release wire 60 by removal of the release handle mechanism 12 (see Figure 1 ) enables the nose cone dilator 66 to be retracted to the sheath 56 and the entire deployment device can be withdrawn. Figures 8 and 9 show another embodiment of the present invention. The embodiment is similar to that shown in Figure 1 and the same reference numerals are used for corresponding items.

The deployment device 70 has a guide wire catheter 3 which extends from a distal handle 7 to a proximal tapered nose cone dilator 1 1 , longitudinally through a passageway or lumen 5 of a delivery catheter 4 which is connected to the handle 7 at its distal end. An introducer sheath 10 fits coaxially around the delivery catheter 4 and extends from a tapered proximal end 13 which optionally includes a radio opaque marker to a connector valve and manipulator 14 attached about distal end 1 5 of the sheath. The introducer sheath 10 extends proximally to the nose cone dilator 1 1 and covers the stent graft 6 during introduction of the deployment device into a patient and is withdrawn distally to expose the stent graft 6 during deployment when the deployment device is in a selected position within the vasculature of a patient.

The sheath in this embodiment is flexible but has a preformed curve 10a towards its proximal end so that the delivery device can more easily conform to the shape of the thoracic arch without putting an unacceptable stress against the

wall of the thoracic arch. The preformed curved portion of the introducer sheath 10 is sufficiently flexible, however, that when it is retracted back to the pusher catheter 4 as shown in Figure 9 the curved portion 10a of the introducer sheath 10 straightens out. The guide wire catheter 3 also has a preformed curve 3a just distal of the nose cone dilator 1 1 , again so that the delivery device can more easily conform to the shape of the thoracic arch without putting an unacceptable stress against the wall of the thoracic arch.

The stent graft or implantable device 6 is carried on the guide wire catheter 3 proximally of the delivery catheter 4 and distally of the nose cone dilator 1 1.

The stent graft 6 can be seen clearly in Figure 9, in which the sheath 10 is shown retracted onto the pusher catheter 4. The stent graft 6 comprises a tubular body 22 of a biocompatible material and a plurality of self expanding stents (not shown for clarity). In this embodiment the stent graft has a scallop 72 at its proximal end 74.

When correctly deployed the scallop will allow access to the left subclavian artery from the thoracic arc while still allowing a sufficient sealing region or landing zone between the thoracic arch and the aneurysm.

Connector valve 14 includes a silicone disk (not shown) for preventing the backflow of fluids therethrough. The disk includes a slit for the insertion of the nose cone dilator 1 1 and delivery catheter 4. Connector 14 also includes side arm 16 to which a tube 17 is connected for introducing and aspirating fluids therethrough. Nose cone dilator 1 1 includes a tapered proximal end 19 for accessing and dilating a vascular access site over a well-known and commercially available wire guide (not shown).

To deploy the stent graft a wire guide is inserted in the vessel with an introducer needle using, for example, the well-known percutaneous vascular access Seldinger technique. A well-known male Luer lock connector hub 20 is attached at the distal end of the guide wire catheter 3 for connection to syringes and other medical apparatus. The handle 7 at the distal end of the pusher catheter 4 remains outside a patient in use and carries the trigger wire release

handle mechanisms 8, 9 and 12 used to release the various portions of the stent graft. The proximal end the stent graft 6 is retained on the delivery device by the use of trigger wires (not shown) connected to the release handle 9, the distal end of the stent graft is retained on the delivery device by the use of trigger wires (not shown) connected to the release handle 8. The handle also includes a release mechanism 12 for a release wire for the longitudinal portion of the stent graft as is discussed below.

A release wire 20 extends from the release mechanism 12 on the handle 7 through the lumen 5 in the delivery catheter 4 and exits at the proximal end of the delivery catheter 4, as shown in Figure 2. The release wire 20 is then wound around the guide wire catheter 3 and through the material of the tubular body 22 in a spiral fashion so that there are lengths 24 of release wire 20 outside the tubular body and turns 26 of release wire 20 around the guide wire catheter 3. This arrangement holds the guide wire catheter 3 against a selected longitudinal portion of the stent graft. When the stent graft is deployed into the vasculature of a patient and the device is deployed into a curved vessel the curved guide wire catheter 3a of the deployment device will take up a position in the greater radius side of the curve. Hence the longitudinal portion of the stent graft which is releasably bound to the guide wire catheter will also take up a position at the greater radius side of the curve. This means that a stent graft with a fenestration or scallop which is to be deployed on the greater radius side of the curve can be mounted onto the deployment device with the fenestration or scallop adjacent the guide wire. Once deployed, the scallop or fenestration will be easier to position correctly. When it is desired to release the stent graft, the release wire 20 can be withdrawn by removal of the release wire mechanism 12 which will release the stent graft from its engagement with the guide wire catheter.

Throughout this specification various indications have been given as to the scope of this invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for limitation.

Throughout this specification and the claims that follow unless the context requires otherwise, the words 'comprise' and 'include' and variations such as 'comprising' and 'including' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.