Method of monitoring positioning of polymer stents

Abstract

The invention is directed to a polymer stent with one or more markers such that when the stent is placed within a lumen, the markers can be detected external to the body. The markers can also be used to monitor the stent position after placement and absorption of bioabsorbable stents. Further, the stent may comprise two markers used to determine the diameter of the stent in real time. It is also contemplated that the stent may comprise at least three markers. The use of at least three markers enables the three dimensional orientation of the stent to be determined at any time. The stent may also comprise markers such that the markers are located in regions with different in vivo lifetimes. It is also contemplated that the pattern and material type of markers on the stent may be used to determine the type of stent within a lumen or box.

1 - 30 . (canceled) 
   
   
       31 . A polymer stent for implantation within a body lumen of a patient, said stent comprising:
 a plurality of struts,   a first predetermined inner diameter in a production state and a second predetermined diameter in an expanded state; and   at least one marker that is imagable external to the body.   
   
   
       32 . The stent of  claim 31 , wherein the marker is a metal or metal alloy. 
   
   
       33 . The stent of  claim 32 , wherein the metal or metal alloy comprises gold. 
   
   
       34 . The stent of  claim 33 , wherein said marker is colloidal gold. 
   
   
       35 . The stent of  claim 31 , wherein the marker has a thickness in the range of 1 micron to 20 microns. 
   
   
       36 . The stent of  claim 31 , wherein said marker is deposited onto the stent by a heated filament under a vacuum or reduced air pressure. 
   
   
       37 . The stent of  claim 31 , wherein the marker is attached to the stent by a means selected from the group consisting of: crimping, folding, tying, melting, use of a knitted mesh, binding by use of a glue compound, and winding around the polymer in a helical or zig-zag design. 
   
   
       38 . The stent of  claim 37 , wherein the marker is crimped onto the stent. 
   
   
       39 . The stent of  claim 31 , wherein the stent is self-expanding. 
   
   
       40 . The stent of  claim 31 , wherein the stent comprises at least two markers. 
   
   
       41 . The stent of  claim 40 , wherein the at least two markers are placed such that the length of the stent can be determined. 
   
   
       42 . The stent of  claim 31 , wherein the stent comprises at least three markers for allowing spatial placement of an unhomogenous shape of stent. 
   
   
       43 . The stent of  claim 42 , wherein the at least three markers are placed such that the three-dimensional orientation of the stent can be determined. 
   
   
       44 . The stent of  claim 31 , wherein the stent comprises at least one in vivo degradation region. 
   
   
       45 . The stent of  claim 44 , wherein the stent comprises at least two in vivo degradation regions. 
   
   
       46 . The stent of  claim 45 , wherein the markers are placed upon stent regions having at least two different in vivo degradation rates. 
   
   
       47 . A method of determining the length of stent placed within a body lumen of a patient, said method comprising:
 crimping a first and second markers upon a stent so that the markers are spatially oriented such that the markers lie on a line with a component vector parallel to the longitudinal axis of the stent;   placing a polymer stent having a plurality of struts within a body lumen of a patient;   generating a signal from the first and second markers by use of a machine external to the body lumen of the patient;   determining the location of the first and second marker relative to one another;   calculating the distance between the first and second marker by use of a software program.   
   
   
       48 . A method of determining the diameter of stent placed within a body lumen of a patient, said method comprising:
 crimping a first and second marker upon a stent so that the markers are spatially oriented such that the markers lie on a line with a component vector perpendicular to the longitudinal axis of the stent;   placing a polymer stent having a plurality of struts within a body lumen of a patient;   generating a signal from the two markers by use of a machine external to the body lumen of the patient;   determining the location of the first and second marker relative to one another;   calculating the distance between the first and second marker by use of a software program.   
   
   
       49 . The method of  claim 48 , wherein the signal generated is by an x-ray. 
   
   
       50 . The method of  claim 48 , whereby the distance between the first and second marker is compared to an ideal distance to find if there was an error with stent deployment. 
   
   
       51 . A method of determining the three dimensional orientation of stent placed within a body lumen of a patient, said method comprising:
 crimping a first and second marker upon a stent so that the markers are spatially oriented such that the markers lie on a line with a component vector perpendicular to the longitudinal axis of the stent;   crimping a third marker upon the stent so that the third marker is spatially oriented such that the third marker lies on a line with a component vector parallel to the longitudinal axis of the stent;   placing a polymer stent having a plurality of struts within a body lumen of a patient;   generating a signal from the three markers by use of a machine external to the body lumen of the patient;   determining the location of the first, second and third marker relative to one another;   calculating the distance between any of the first, second marker and third by use of a software program.   
   
   
       52 . The method of  claim 51 , whereby the distance between any of the first, second and third marker is compared to an ideal distance to find if there was an error with stent deployment. 
   
   
       53 . The method of  claim 51 , whereby the movement of the first, second and third marker within a body lumen of a patient may be tracked to determine if the stent is rotating within the lumen. 
   
   
       54 . The method of  claim 47 , wherein said markers are a metal or metal alloy. 
   
   
       55 . The method of  claim 54 , wherein the metal or metal alloy comprises gold. 
   
   
       56 . The method of  claim 47 , wherein the marker has a thickness in the range of 1 micron to 20 microns. 
   
   
       57 . The method of  claim 47 , wherein the stent is self-expanding. 
   
   
       58 . The method of  claim 47 , wherein the stent has at least one in vivo degradation region. 
   
   
       59 . The method of  claim 58 , wherein the stent has at least two in vivo degradation regions.