Delivery system having a rapid pusher assembly for self-expanding stent, and stent exchange configuration

• US 20040199240A1
• Filed: 03/31/2004
• Published: 10/07/2004
• Est. Priority Date: 07/06/2001
• Status: Active Grant

• Current Assignee: Angiomed GmbH & Co. Medizintechnik KG
• Original Assignee: Angiomed GmbH & Co. Medizintechnik KG
• Inventors: Dorn, Jurgen
• Granted Patent: US 8,075,606 B2
• Time in Patent Office: Days
• US Class Current: 623/1.11
• CPC Class Codes: A61F 2/95 Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61F 2/966 with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod
• CPC Class Codes: A61F 2250/0098 radio-opaque, e.g. radio-opaque markers

Abstract

A pusher assembly for a delivery system for a sell-expanding stent (6) which is delivered by proximal withdrawal of a sheath (4) radially surrounding the stent has a stent pusher element (8) which defines a lumen for a guidewire (2), a pusher strand (16) that extends to the proximal end of the delivery system and bears an end-wise compressive stress during release of the stent. A transfer shaft (12) links the distal end of the pusher strand (16) to the pusher element (8) and lies side-by-side with the guidewire (2). In a rapid exchange version, an adapter (20) provides two lumens side-by-side, one (22) carrying the pusher strand (16) and the other (14) defining a proximal guidewire part. To the adapter is mounted the proximal end of the stent sheath (4). The system allows modular (14) construction, a tapered tip (4A) on the sheath, and an uncluttered internal configuration which facilitates passage of pulses (F) of liquids from the proximal to the distal end of the system.

Claims

1. A pusher assembly for a delivery system for a self-expanding stent, the pusher assembly constituting a catheter shaft with a proximal pusher end to receive an end-wise compressive force and a distal pusher end (8) to deliver said force to a stent (6) to be delivered, the pusher assembly comprising:

a pusher strand (16) extending from the proximal pusher end to a distal strand end which is nearer the distal pusher end than the proximal pusher end; and

a pusher element (8) which abuts the stent (6) in use to deliver said force to the stent;

a transfer shaft (12) having a proximal end and a distal end, the proximal end being connected to the distal strand end and the distal end being connected to the pusher element (8);

the pusher element (8) defines a guidewire path, and said transfer shaft (12) lies to one side of said path.

2. Assembly as claimed in claim 1 wherein the transfer shaft (12) is welded to at least one of the pusher element (8) and the pusher strand (16).

3. Assembly as claimed in claim 1 wherein the pusher element (8) is a cylinder with a distal-facing end face to abut the proximal end of the stent (6).

4. Assembly as claimed in claim 1 wherein the pusher element (8) is a radiopaque marker.

5. Assembly as claimed in claim 1 further comprising a carrier tube and wherein the pusher element (8) surrounds a carrier tube (10) itself carried on the pusher element (8) and cantilevered distally from the pusher element (8) to lie in use within the lumen of a stent (6) to be delivered.

6. Assembly as claimed in claim 5 further comprising a radiopaque marker (26) on the carrier tube for marking the distal end of the stent.

7. Assembly as claimed in one of claims 5 or 6 wherein a proximal portion of the carrier tube (10) extends proximally from the pusher element (8) and flares outwardly proximally.

8. Assembly as claimed in claim 1 in which the transfer shaft (12) is present as two shaft portions joined by a connection piece (14).

9. Assembly as claimed in claim 8 wherein the connection piece (14) is a collar.

10. Assembly as claimed in one of claims 8 or 9 wherein each of the transfer shaft portions is soldered to the connection piece (14).

11. A self-expanding stent deployment system for advancement over a guidewire (2) and having a rapid exchange configuration, comprising:

a tubular sheath (4) defining a cavity within which a stent (6) is confinable radially inwardly until deployment, the sheath (4) having a distal end and a proximal end and defining an axis of the system;

a pipe (18) to pull the sheath (4) proximally to release the stent (6) and having a lumen to transport fluid (F) for delivery to the sheath cavity;

a pusher assembly including a pusher element (8) for abutting the stent (6) in use and a rod (16) for restraining the pusher element (8) against proximal movement and extending from a proximal rod end proximally beyond the proximal end of the sheath (4) along the lumen of the pipe (18) to a distal rod end, the rod (16) being capable of carrying an endwise compressive stress (C) suffered by the pusher assembly during deployment of the stent (6);

an adapter (20) defining at least first (24) and second lumens (22) arranged side by side and parallel with the axis of the system and arranged to transmit forces between the sheath (4) and the pipe (18), wherein the first lumen (24) is a guidewire (2) lumen, and the second lumen (22) communicates with the lumen of the pipe (18) and with the sheath (4) cavity, and

the sheath (4) having a tapered tip, distal of the stent (6) cavity which enables the guidewire (2) to pass distally beyond the distal end of the sheath (4).

12. The system according to claim 11, further comprising the pusher element (8) is a cylinder with a distal-facing end face to abut the proximal end of the stent (6).

13. The system according to claim 11 wherein the pusher element (8) constitutes a radiopaque marker.

14. The system according to claim 11 further comprising a transfer shaft (12) which lies inside the sheath (4) to one side of the axis of the sheath and is arranged to transmit forces between the pusher element (8) and the rod (16).

15. The system according to claim 14, wherein the transfer shaft (12) is welded to at least one of the pusher element (8) and the rod (16).

16. The system according to either one of claims 14 or 15, wherein the transfer shaft (12) comprises two shaft portions joined by a connection piece (14).

17. The system according to claim 16, characterised in that the connection piece (14) is a collar.

18. The system according to claim 16, characterised in that each of the transfer shaft (12) portions is soldered to the connection piece (14).

19. The system according to claim 11 wherein the adapter (20) is made of metal.

20. The system according to claim 11 wherein the connection between the sheath (4) and the adapter (20) is made by means of an adhesive.

21. The system according to claim 11 wherein the sheath (4) comprises an encapsulated metal braid (3).

22. The system according to claim 21 further comprising metal studs (20A) disposed around the circumferential surface of the distal end of the adapter (20), the studs cooperatively engaging the metal braid (3).

23. The system according to claim 11 wherein the first lumen (24) is defined by two arcuate segments (23A) and (23B).

24. The system according to claim 11 wherein the pipe (18) is inserted into the first lumen (24) of the adapter (20) until it abuts an end face of a recess provided on the defining walls of the first lumen (24).

25. The system according to claim 11 further comprising a carrier tube and wherein the pusher element (8) surrounds the carrier tube (10) itself carried on the pusher element (8) and cantilevered distally from the pusher element (8) to lie in use within the lumen of the stent (6) to be delivered.

26. The system according to claim 25 wherein the carrier tube (10) itself carries a radiopaque marker (26) for the distal end of the stent (6).

27. The system according to claim 23 wherein a proximal portion of the carrier tube (10) extends proximally from the pusher element (8) and flares outwardly proximally.

28. As assembly as defined in claim 11 further comprising, in combination, a stent contained within the distal region of the sheath in a compressed configuration.

29. A process for assembling a self-expanding stent and a delivery device for the stent comprising:

providing a sheath dimensioned to contain a self-expanding stent in a compressed configuration smaller in diameter than that to which the stent may expand when released from the sheath;

a proximal tubular member connected to the proximal end of the sheath;

a proximal pusher strand disposed within the proximal tubular member, the pusher strand having a proximal end and a distal end;

providing a transfer shaft having a proximal end and a distal end, the length of the transfer shaft being selected with respect to the length of the sheath and the stent such that when the stent is contained within the distal portion of the sheath, the transfer shaft will extend from the distal end of the pusher strand to the region immediately adjacent the proximal end of the stent;

connecting the proximal end of the selected transfer shaft to the distal end of the pusher strand;

the distal end of the transfer shaft having a pusher element attached thereto, the pusher element defining a guidewire path and being adapted to engage the proximal end of a stent contained within the sheath;

the transfer shaft being disposed to one side of the guidewire path; and

placing a stent within the distal portion of the sheath.

30. A catheter comprising a proximal shaft portion and a distal shaft portion attached to the proximal shaft portion, and means to stiffen the catheter at the junction between the proximal shaft portion and the distal shaft portion;

the catheter having a guidewire opening located a substantial distance distally of the proximal end of the catheter for rapid exchange of the catheter over a guidewire.

31. A catheter as defined in claim 30 wherein the guidewire opening is provided by an opening in the means to stiffen the catheter.

32. A catheter as defined in claim 31 wherein the means to stiffen the catheter comprises a mounting piece for attaching the distal shaft portion to the proximal shaft portion.

33. A catheter as defined in claim 31 wherein the guidewire opening faces in a direction substantially parallel to the longitudinal axis of the catheter.

34. A catheter as defined in claim 31 further comprising means to guide passage of a guidewire through the guidewire opening in the catheter.