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EP-4740915-A2 - SCAFFOLDS HAVING A RADIOPAQUE MARKER AND METHODS FOR ATTACHING A MARKER TO A SCAFFOLD

EP4740915A2EP 4740915 A2EP4740915 A2EP 4740915A2EP-4740915-A2

Abstract

A scaffold includes a radiopaque marker connected to a strut. The marker is retained within the strut by a head at one or both ends. The marker is attached to the strut by a process that includes forming a rivet from a radiopaque bead and attaching the rivet to the marker including deforming the rivet to enhance resistance to dislodgement during crimping or balloon expansion. The strut has a thickness of about 100 microns.

Inventors

  • LUMAUIG, ROMMEL
  • HARRINGTON, JOEL
  • ABUNASSAR, CHAD
  • HART, David D.
  • CIUREA, Cornel I.
  • RITCHIE, MARK A.
  • KING, JAY A.
  • MCCOY, Jill

Assignees

  • Abbott Cardiovascular Systems Inc.

Dates

Publication Date
20260513
Application Date
20160610

Claims (15)

  1. A method of attaching a radiopaque material to a scaffold, comprising: deforming a spherical bead into a rivet having a head and a shank, the bead comprising radiopaque material; attaching a tool to the head of the rivet, including creating a pressure difference at a tip of the tool to adhere the head of the rivet to the tip of the tool to enable the tool to lift the rivet and maintain an orientation of the rivet relative to the tip; placing the shank through a hole of a scaffold, wherein the head of the rivet rests on one of a luminal surface or an abluminal surface of a strut of the scaffold and a tail of the shank extends out from the other of the luminal surface or the abluminal surface; and forming an interference fit between the rivet and the scaffold including deforming the tail.
  2. The method of claim 1, wherein the scaffold is a polymeric scaffold.
  3. The method of claim 1, wherein the spherical bead is deformed using a die, and wherein the rivet is removed from the die by the tool and the tool transfers the rivet to the scaffold without removing the rivet from the tip of the tool, thereby maintaining the orientation of the shank relative to the tip.
  4. The method of claim 3, wherein the die comprises a plate having a hole and a counter bore.
  5. The method of claim 3, wherein the die comprises a plate having a tapered hole, such that the shank of the rivet is tapered.
  6. The method of any one of claims 1 to 5, wherein the scaffold has a strut thickness and the shank of the rivet has a length that is between 125% and 150% of the strut thickness.
  7. The method of any one of claims 1 to 6, wherein the hole is a tapered hole after forming the interference fit.
  8. The method of any one of claims 1 to 7, wherein forming the interference fit includes deforming the shank of the rivet into a frustum.
  9. The method of any one of claims 1 to 8, wherein the hole is a polygonal hole or an elliptical hole before forming the interference fit.
  10. The method of any one of claims 1 to 9, wherein the tip of the tool comprises a vacuum tip configured for grabbing the head of the rivet and releasing the head therefrom by modifying a gas pressure at the tip.
  11. The method of any one of claims 1 to 10, wherein the hole includes a groove formed about a perimeter.
  12. The method of claim 11, wherein the groove is between an upper rim and a lower rim of the hole.
  13. The method of any one of claims 1 to 12, wherein the rivet has a total length of 190-195 microns and/or a diameter of 300-305 microns.
  14. The method of any one of claims 1 to 13, wherein forming the interference fit includes forming the interference fit between the rivet and the hole of the scaffold.
  15. A medical device made according to the method of any one of claims 1 to 14.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to bioresorbable scaffolds; more particularly, this invention relates to bioresorbable scaffolds for treating an anatomical lumen of the body. Description of the State of the Art Radially expandable endoprostheses are artificial devices adapted to be implanted in an anatomical lumen. An "anatomical lumen" refers to a cavity, or duct, of a tubular organ such as a blood vessel, urinary tract, and bile duct. Stents are examples of endoprostheses that are generally cylindrical in shape and function to hold open and sometimes expand a segment of an anatomical lumen. Stents are often used in the treatment of atherosclerotic stenosis in blood vessels. "Stenosis" refers to a narrowing or constriction of the diameter of a bodily passage or orifice. In such treatments, stents reinforce the walls of the blood vessel and prevent restenosis following angioplasty in the vascular system. "Restenosis" refers to the reoccurrence of stenosis in a blood vessel or heart valve after it has been treated (as by balloon angioplasty, stenting, or valvuloplasty) with apparent success. The treatment of a diseased site or lesion with a stent involves both delivery and deployment of the stent. "Delivery" refers to introducing and transporting the stent through an anatomical lumen to a desired treatment site, such as a lesion. "Deployment" corresponds to expansion of the stent within the lumen at the treatment region. Delivery and deployment of a stent are accomplished by positioning the stent about one end of a catheter, inserting the end of the catheter through the skin into the anatomical lumen, advancing the catheter in the anatomical lumen to a desired treatment location, expanding the stent at the treatment location, and removing the catheter from the lumen. The following terminology is used. When reference is made to a "stent", this term will refer to a permanent structure, usually comprised of a metal or metal alloy, generally speaking, while a scaffold will refer to a structure comprising a bioresorbable polymer, or other resorbable material such as an erodible metal, and capable of radially supporting a vessel for a limited period of time, e.g., 3, 6 or 12 months following implantation. It is understood, however, that the art sometimes uses the term "stent" when referring to either type of structure. Scaffolds and stents traditionally fall into two general categories - balloon expanded and self-expanding. The later type expands (at least partially) to a deployed or expanded state within a vessel when a radial restraint is removed, while the former relies on an externally-applied force to configure it from a crimped or stowed state to the deployed or expanded state. Self-expanding stents are designed to expand significantly when a radial restraint is removed such that a balloon is often not needed to deploy the stent. Self-expanding stents do not undergo, or undergo relatively no plastic or inelastic deformation when stowed in a sheath or expanded within a lumen (with or without an assisting balloon). Balloon expanded stents or scaffolds, by contrast, undergo a significant plastic or inelastic deformation when both crimped and later deployed by a balloon. In the case of a balloon expandable stent, the stent is mounted about a balloon portion of a balloon catheter. The stent is compressed or crimped onto the balloon. Crimping may be achieved by use of an iris-type or other form of crimper, such as the crimping machine disclosed and illustrated in US 2012/0042501. A significant amount of plastic or inelastic deformation occurs both when the balloon expandable stent or scaffold is crimped and later deployed by a balloon. At the treatment site within the lumen, the stent is expanded by inflating the balloon. The stent must be able to satisfy a number of basic, functional requirements. The stent (or scaffold) must be capable of sustaining radial compressive forces as it supports walls of a vessel. Therefore, a stent must possess adequate radial strength. After deployment, the stent must adequately maintain its size and shape throughout its service life despite the various forces that may come to bear on it. In particular, the stent must adequately maintain a vessel at a prescribed diameter for a desired treatment time despite these forces. The treatment time may correspond to the time required for the vessel walls to remodel, after which the stent is no longer needed. Examples of bioresorbable polymer scaffolds include those described in U.S. Patents No. 8,002,817 to Limon, No. 8,303,644 to Lord, and No. 8,388,673 to Yang. FIG. 1 shows a distal region of a bioresorbable polymer scaffold designed for delivery through anatomical lumen using a catheter and plastically expanded using a balloon. The scaffold has a cylindrical shape having a central axis 2 and includes a pattern of interconnecting structural elements, which will be called bar arms or struts 4