Scaffolds having radiopaque markers

Abstract

A scaffold includes a radiopaque marker connected to a strut. The marker is retained within the strut by one or more of a mechanical interference fit, a polymer coating or melt, and/or by friction. The marker can take the form of a bead, rivet or snap-in marker, or a tube deformed when attached to the strut. The strut is made from a tube. The strut has a thickness of about 100 microns.

1 . A method for making a medical device, comprising:
 providing a polymer scaffold including a strut having a hole formed in the strut, wherein the hole has a length, a width, and a hole opening located on a first side and a second side of the strut; and   using a rivet comprising a radiopaque material and having a head and a shank, wherein a diameter of the head is greater than a diameter of the shank, the shank includes a tail and a medial portion, and the shank's medial portion is between the tail and the head;   attaching the rivet to the scaffold including placing the shank into the hole; and   deforming the tail, whereupon the deformed tail has a width that exceeds the hole width.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The method of  claim 1 ,
 wherein the first side and the second side are a luminal side and an abluminal side, respectively, of the hole opening,   wherein the head is placed at the luminal side and held in place by a mandrel disposed within a bore of the scaffold, and the tail extends from the abluminal side of the hole opening, and   the deforming step includes compressing the rivet between a roller or a pin applied to the tail at the abluminal side, and a surface of the mandrel applied to the head at the luminal side of the opening.   
     
     
         5 - 7 . (canceled) 
     
     
         8 . The method of  claim 1 , wherein the marker has an undeformed length L measured from the head to the tail and before the deforming step, a deformed length L′ measured from the head to the deformed tail, the strut has a thickness t, and
 wherein the marker lengths L, L′ and strut thickness t are related as 1.2≤L/t≤1.8 and 1.1≤(L′/t)≤1.5. 
 
     
     
         9 . The method of  claim 1 , wherein the scaffold comprises a polymer having a glass transition temperature (TG), and the scaffold is heated 0-20 degrees above TG when the shank is placed in the hole. 
     
     
         10 . The method of  claim 1 , wherein the polymeric scaffold comprises a polymer having a glass transition temperature (TG), and the scaffold is heated 0-20 degrees above TG after the shank is placed in the hole. 
     
     
         11 . The method of  claim 1 , wherein the radiopaque material is platinum, platinum/iridium alloy, iridium, tantalum, palladium, tungsten, niobium, zirconium, iron, zinc, magnesium, or manganese, or their alloys. 
     
     
         12 - 20 . (canceled) 
     
     
         21 . The method of  claim 1 , wherein the scaffold is made from a polymer comprising poly(L-lactide),
 wherein the scaffold has a wall thickness between 80 and 120 microns, and   wherein following the deforming step a distance measured from the head to the deformed tail is between 100 microns and 150 microns.   
     
     
         22 . The method of  claim 1 , wherein the hole width is a diameter and the deformed tail width is a greater than the diameter of the hole. 
     
     
         23 . The method of  claim 1 , wherein the hole diameter is about the same as the shank diameter before the deforming step.