WO1999047074A1

WO1999047074A1 - Stent delivery

Info

Publication number: WO1999047074A1
Application number: PCT/GB1999/000620
Authority: WO
Inventors: David Moore
Original assignee: Biocompatibles Limited
Priority date: 1998-03-13
Filing date: 1999-03-02
Publication date: 1999-09-23
Also published as: AU3262899A

Abstract

A device for delivering a stent into a body lumen has a stent support member for attachment, in use, to the distal end of a delivery member arranged to pass through the body lumen. The member is arranged to support, in use, a stent placed thereon. A sheath covers, in use, the external surface of a stent, the sheath comprising a continuous sheath thread wound, in use, around the exterior surface of the stent so as to form a helix and so as to retain the stent in position on the support member. Sheath removing means allows the sheath thread to unwind freely from the stent upon movement of one end of the thread toward the distal end of the delivery member.

Description

1 STENT DELIVERY

The present invention relates to the delivery of implantable stents to their desired location within a body lumen. The lumen may be a peripheral or coronary blood vessel, or may be a bile duct, ureter, oesophagus or ileum. There are several different category of stent. The three main categories are heat-expandable devices, balloon- expandable devices, and self-expanding devices. The present invention is generally concerned with the delivery of self-expanding devices, that is devices which are inserted into the body lumen in a radially compressed condition and which are biased toward a radially expanded position. It may, however, be employed with other categories of stent.

With self-expanding stents the release of the stent in the body lumen allows for the stent to expand radially exerting outwardly directed pressure upon the inner surface of the wall of the body lumen in which it is positioned. Traditionally, such stents have been delivered by moving them to the appropriate position in the body lumen within a rigid sleeve, which holds them in their compressed state, and then removing the sleeve and allowing the stent to expand. Such delivery systems do, however, have a number of problems associated with them. Firstly, as the stent generally contracts axially upon radial expansion, it is difficult to position the ends of the stent, particularly the proximal end, accurately with such delivery devices. This is a particular problem for urological stents, in which mis-alignment of the stent within the urethra can cause incontinence, if one end interferes with the sphincter or encrustation of the stent at the other end if it extends into the bladder.

A further problem associated with such delivery system is that operator contact with the stent can lead to its becoming contaminated or any biocompatible surface that it has being damaged prior to insertion. According to the present invention there is provided a device for delivering a stent into a body lumen, the device comprising: a stent support member for attachment, in use, to the distal end of a delivery member arranged to pass through the body lumen, the member being arranged to support, in use, a stent placed thereon; a sheath covering, in use, the external surface of a stent, the sheath comprising a continuous sheath thread wound, in use, around the exterior surface of the stent so as to form a helix and so as to retain the stent in position on the support member; and sheath removing means for allowing the sheath thread to unwind freely from the stent upon movement of one end of the thread toward the distal end of the delivery member.

The sheath removing means may be a ring attached to the stent support member and may have a low friction surface across which the sheath thread can slide. The sheath removal means may also be attached to the stent support member in such a manner that it rotates around a central axis, the removing means rotating upon movement of the thread toward the delivery member to allow smooth removal of the thread from the surface of the stent without the need for excessive force. The sheath removing means may be positioned at the distal end of the support member.

The thread may be wound around the stent in such a manner that adjacent turns of the helix which it forms are in contact with one another. This ensures that no portion of the stent can expand prior to removal of the sheath (if delivering a self-expanding stent) and also protects the stent from contamination prior to insertion.

The stent may be of the helically braided type. The thread may be wound so that its removal uncovers the end of the stent nearest the proximal end of the delivery member before uncovering the other end. This allows for accurate positioning of the proximal end by an clinician. The sheath thread may be formed from polyester, nylon, or may be a silk suture.

The thread may be held in position by retaining means, such as a resin of low shear strength, to ensure that the thread does not unwind prior to stent positioning.

The delivery member may include an endoscope and the stent support member may be arranged for attachment thereto in use. Alternatively the delivery member may have a lumen arranged to accept an endoscope. With such arrangements the stent support member may be arranged to allow the objective lens of the endoscope to view an end of the stent during the insertion process.

One example of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of a delivery device according to the invention prior to delivery of the stent:

Figure 2 is a schematic diagram of the device of the present invention during stent delivery; and Figure 3 is a schematic diagram of the device of the present invention after delivery of a stent.

Referring to figure 1, a delivery device according to the invention is attached, in use, to a delivery member 1.

In this case, the delivery member 1 is a casing arranged around an endoscope 2 with objective lens 3. The endoscope

2 may be rigid or flexible.

The delivery device has a generally tubular stent support member 4 which attaches to the delivery member 1. In use the support member 4 has a stent 5 placed on it, the stent 5 being retained on the support member 4 by a thread 6 wound around the exterior of the stent 5 in a helical manner. The thread 6 in this example holds the stent 5 in a compressed state. The thread 6 is wound around the stent 5 in such a manner that, when it is unwound it releases the proximal end 7 of the stent 5 first (see figure 2) . A free end of the thread 6 passes over a sheath removing means 10 which is formed from a ring disk 11 rotatably coaxially attached to the support member 4 by a bearing 12.

As the thread 6 is removed from the surface of the stent 5 and slides over the surface of the ring, the ring 11 rotates ensuring smooth and snag-free removal of the thread. In certain applications it may be possible to simply provide a ring 11 having a smooth low friction surface over which the thread 6 moves but which is attached rigidly to the support member 4. Once the thread 6 has been removed fully from the surface of the stent 5 , the stent support member 4 and attached ring 11 can be withdrawn from the middle of the stent 5 which has now expanded to engage with the wall of the body lume . So that a clinician can see the stent 5 and position the stent 5 accurately a viewing port is provided in the delivery member 1 or the stent support member 4.

As can be seen from figure 2, as the stent is delivered from the proximal end of the delivery member first, positioning of the end of the stent 5 can be extremely accurate and is unaffected by a change in axial length of the stent as it is delivered. Also, as the stent is fully encased until its delivery, the possibility of stent damage by the clinician or during storage is reduced significantly.

As can be seen from figure 1, this example of the invention has a sheath thread 6 which continues through to the proximal end of the delivery member 1. It will be appreciated, however, that it could extend simply to the distal end of the delivery member 1, with its free end being capable of attachment to a snare or hooking device so that it can be drawn through a lumen in the delivery member 1 or endoscope for stent delivery.

Claims

1. A device for delivering a stent into a body lumen, the device comprising: a stent support member for attachment, in use, to the distal end of a delivery member arranged to pass through the body lumen, the member being arranged to support, in use, a stent placed thereon; a sheath covering, in use, the external surface of a stent, the sheath comprising a continuous sheath thread wound, in use, around the exterior surface of the stent so as to form a helix and so as to retain the stent in position on the support member; and sheath removing means for allowing the sheath thread to unwind freely from the stent upon movement of one end of the thread toward the distal end of the delivery member.

2. A device according to claim 1, wherein the sheath removing means is a ring attached to the stent support member and has a low friction surface across which the sheath thread can slide.

3. A device according to claim 1 or claim 2, wherein the sheath removal means is attached to the stent support member in such a manner that it rotates around a central axis, the removing means rotating upon movement of the thread toward the delivery member to allow smooth removal of the thread from the surface of the stent.

4. A device according to any of the preceding claims, wherein the sheath removing means is positioned at the distal end of the support member.

5. A device according to any of the preceding claims, wherein the thread is wound around the stent in such a manner that adjacent turns of the helix which it forms are in contact with one another.

6. A device according to any of the preceding claims, further including a stent.

7. A device according to claim 6, wherein the stent is of the helically braided type.

8. A device according to any of the preceding claims, wherein the thread is wound so that its removal uncovers the proximal end of the stent before uncovering the distal end.

9. A device according to any of the preceding claims, wherein the sheath thread is formed from polyester.

10. A device according to any of the preceding claims, wherein the sheath thread is a silk suture.

11. A device according to any of the preceding claims, wherein the thread is held in position by retaining means to ensure that the thread does not unwind prior to stent positioning.

12. A device according to any of the preceding claims, wherein the delivery member includes an endoscope and the stent support member is arranged for attachment thereto in use.

13. A device according to any of the preceding claims, wherein the delivery member has a lumen arranged to accept an endoscope.

14. A device according to claim 12 or claim 13, wherein the stent support member is arranged to allow the objective lens of the endoscope to view the proximal end of the stent during an insertion process.