Stent made by rotational molding or centrifugal casting and method for making the same

• US 6,574,851 B1
• Filed: 07/31/2000
• Issued: 06/10/2003
• Est. Priority Date: 07/31/2000
• Status: Active Grant

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Advanced Cardiovascular Systems Incorporated
• Inventors: Mirizzi, Michael S.
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): Blanco, Javier G.
• Application Number:
  US09/629,075
• Time in Patent Office: 1,044 Days
• Field of Search: 295/271, 295/275, 623/1.11, 264/219, 205/75, 205/667
• US Class Current: 29/527.5
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91516 the meander having a change in frequency along the band
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91575 connected peak to trough
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: B29C 41/003 characterised by the choice of material
• CPC Class Codes: B29C 41/06 about two or more axes
• CPC Class Codes: B29C 41/38 Moulds, cores or other substrates
• CPC Class Codes: Y10T 29/4998 Combined manufacture including applying or shaping of fluent material
• CPC Class Codes: Y10T 29/49988 Metal casting

Abstract

The invention is directed to an expandable or self-expanding stent for implantation in a body lumen, such as an artery. The stent is made from a centrifugal casting process in which liquid casting material is placed within a female mold which includes an elongated cavity having a angular wall formed of grooves cooperating to form a predetermined stent configuration and rotating the female mold to distribute the casting material throughout the network of grooves. The stent can also be made from a rotational molding process in which dry cold powder resin is placed in a female mold and rotated at low speeds and heated to allow the charge of cold powder material to sinter to form the shape of the stent. The invention is also directed to the method for making such stents made from either centrifugal casting or rotational molding processes.

Claims

1. A method of making a stent of a predetermined configuration including:

selecting a female mold formed with an elongated cavity having an annular wall formed with a network of grooves cooperating to form a predetermined stent configuration;

introducing a charge of casting material into the cavity;

rotating the female mold about a rotational axis to distribute the casting material throughout the network of grooves to form the predetermined stent configuration; and

solidifying the casting material to form the stent.

2. The method of claim 1, wherein:

selecting the female mold formed with an elongated cavity includes;

creating a model/pattern of a stent;

placing the model/pattern of the stent on a tooling die; and

pouring mold material over the tooling die to form the female mold.

3. The method of claim 1, further including:

heating the female mold while the female mold is being rotated.

4. The method of claim 3, further including:

cooling the female mold after the female mold has been heated for a predetermined time.

5. The method of claim 4, wherein:

the female mold is still being rotated as the female mold is being cooled.

6. The method of claim 1, wherein:

the casting material is a cold powder resin.

7. The method of claim 1, wherein:

the casting material is a liquid-pourable casting material.

8. The method of claim 1, wherein:

the charge consists of a predetermined amount of casting material which substantially fills the female mold.

9. The method of claim 1, wherein:

the female mold is rotated about a vertical axis.

10. The method of claim 1, wherein:

the female mold is rotated about a horizontal axis.

11. The method of claim 1, wherein:

the female mold is rotated bi-axially.

12. The method of claim 1, wherein:

the network of grooves are configured with undulations.

13. The method of claim 1, wherein:

the cavity is rotating about the rotational axis when the charge is introduced.

14. The method of claim 1, wherein:

the female mold starts to rotate about the axis after the charge of casting material is introduced.

15. The method of claim 1, wherein:

selecting a female mold includes selecting a mold formed with an elongated cavity having an annular wall formed with a network of grooves cooperating to form the outline of an expanded stent.

16. The method of claim 1, wherein:

the stent is formed in a radially compressed condition.

17. The method of claim 1, wherein:

the rotating step includes rotating the female mold cavity at a sufficient tangential velocity to provide a centrifugal acceleration of greater than 1G.

18. The method of claim 1, wherein:

the female mold is formed with a plurality of circumferential grooves having a continuous undulating pattern formed by a plurality of U-shaped pathways linked together in a consecutive alternating inverted relationship; and

at least one interconnecting channel extends longitudinally between adjacent circumferential grooves connecting them together.

19. The method of claim 1, wherein:

the casting material is biocompatible.

20. The method of claim 1, wherein:

the casting material is liquid or pourable metal.

21. The method of claim 1, wherein:

the casting material is liquid or pourable plastic.

22. The method of claim 1, wherein:

the casting material is a powdered polymer.

23. The method of claim 1, wherein:

the casting material is a powdered polymer combined with a drug agent.

24. The method of claim 1, wherein:

the casting material is made from a bioabsorbable material.

25. A method of making a stent of a predetermined configuration including:

selecting a female mold formed with an elongated cavity having an angular wall formed with a network of grooves cooperating to form a predetermined stent configuration;

introducing a charge of casting material into the cavity;

rotating the female mold about a rotational axis to distribute the casting material throughout the network of grooves to form the predetermined configuration;

heating the female mold as it is being rotated about the rotational axis for a predetermined time interval;

cooling the female mold after the expiration of the time period for heating the female mold to allow the female mold and casting material to cool; and

solidifying the casting material to form the stent.

26. The method of claim 25, wherein:

the casting material is a powdered polymer.

27. The method of claim 25, wherein:

the casting material is a powdered polymer combined with a drug agent.