Medical stent and related methods

Abstract

A medical stent is sized for placement in a ureter. The stent includes a first section which includes a first material, defines a lumen, and includes a first coil completing at least one revolution. A second section of the stent includes a second material, defines a lumen, and includes a second coil completing at least one revolution. A third section defines a lumen and is located between the first and second sections. The third section includes a co-extrusion of the first and second materials. One of the first or second sections is harder than the other section.

1 . A medical stent comprising:
 a proximal end portion defining a lumen and including a first retention structure, the proximal end portion constructed from at least a first material having a first durometer value, the first retention structure includes a coil offset from a longitudinal axis of the medical stent;   a distal end portion defining a lumen and including a second retention structure, the distal end portion constructed from at least a second material having a second durometer value, the second durometer value being greater than the first durometer value, the second retention structure includes a coil offset from the longitudinal axis of the medical stent; and   a central portion disposed between the proximal end portion and the distal end portion, the central portion defining a lumen in fluid communication with the lumen of the proximal end portion and the lumen of the distal end portion, the lumen of the central portion defining a longitudinal axis, the central portion constructed from the first material and the second material, the first material and the second material being co-extruded within the central portion such that the first material and the second material are distinct from each other and arranged substantially asymmetrically within a plane normal to the longitudinal axis,   the coil of the proximal end portion having a curved portion that curves away from the longitudinal axis in a first direction, the coil of the distal end portion having a curved portion that curves away from the longitudinal axis is a second direction different than the first direction.   
     
     
         2 . The medical stent of  claim 1 , wherein the relative amounts of the first material and the second material within the central portion vary non-linearly within a plane parallel to the longitudinal axis. 
     
     
         3 . The medical stent of  claim 1 , wherein an outer surface of the central portion smoothly transitions to an outer surface of the proximal end portion and an outer surface of the distal end portion. 
     
     
         4 . The medical stent of  claim 1 , wherein an inner diameter of the central portion, an inner diameter of the proximal end portion adjacent the central portion and an inner diameter of the distal end portion adjacent the central portion are substantially constant. 
     
     
         5 . The medical stent of  claim 1 , wherein the proximal end portion is devoid of the second material and the distal end portion is devoid of the first material. 
     
     
         6 . The medical stent of  claim 1 , wherein the first material includes ethylene vinyl acetate. 
     
     
         7 . The medical stent of  claim 1 , wherein the first material has a durometer value of about 70 to about 90 on a Shore A scale. 
     
     
         8 . The medical stent of  claim 1 , wherein at least one of the proximal end portion, the distal end portion, and the central portion includes a lubricant. 
     
     
         9 . The medical stent of  claim 8 , wherein the lubricant is a hydrophilic material. 
     
     
         10 . A medical stent comprising:
 a proximal end portion defining a lumen and including a first retention structure, the proximal end portion constructed from at least a first material having a first durometer value, the first retention structure includes a coil offset from a longitudinal axis of the medical stent;   a distal end portion defining a lumen and including a second retention structure, the distal end portion constructed from at least a second material having a second durometer value, the second durometer value being greater than the first durometer value, the second retention structure includes a coil offset from the longitudinal axis of the medical stent; and   a central portion disposed between the proximal end portion and the distal end portion, the central portion defining a lumen in fluid communication with the lumen of the proximal end portion and the lumen of the distal end portion, the lumen of the central portion defining a longitudinal axis, the central portion constructed from the first material and the second material, the first material and the second material being co-extruded within the central portion such that the first material and the second material are distinct from each other and arranged substantially asymmetrically within a plane normal to the longitudinal axis,   the relative amounts of the first material and the second material within the central portion vary non-linearly within a plane parallel to the longitudinal axis.   
     
     
         11 . The medical stent of  claim 10 , wherein a lubricant is disposed about an outer surface of the medical stent. 
     
     
         12 . The medical stent of  claim 10 , wherein a proximal end of the first retention structure extends in a direction parallel to longitudinal axis defined by the medical stent. 
     
     
         13 . The medical stent of  claim 10 , wherein an outer surface of the central portion smoothly transitions to an outer surface of the proximal end portion and an outer surface of the distal end portion. 
     
     
         14 . A method of placing a medical stent within a body of a patient, comprising:
 disposing a proximal retention structure of the medical stent within a kidney of the patient, the proximal retention structure being constructed from at least a first material having a first durometer value;   disposing a distal retention structure of the medical stent within a bladder of the patient, the distal retention structure being constructed from at least a second material having a second durometer value, the second durometer value being greater than the first durometer value; and   disposing at least a portion of a central portion of the medical stent within a ureter of the patient, the central portion of the medical stent being located between the proximal retention structure and the distal retention structure, the central portion being constructed from the first material and the second material, the first material and the second material being co-extruded within the central portion such that the first material and the second material are distinct from each other and arranged substantially asymmetrically within a plane normal to the longitudinal axis.   
     
     
         15 . The method of  claim 14 , wherein the proximal retention structure includes a curved portion and the disposing a proximal retention structure includes moving the curved portion of the proximal retention structure to a linear configuration. 
     
     
         16 . The method of  claim 14 , wherein the proximal retention structure includes a curved portion, the disposing a proximal retention structure includes moving the curved portion of the proximal retention structure to a substantially linear configuration, the distal retention structure includes a curved portion, the disposing a distal retention structure includes moving the curved portion of the distal retention structure to a substantially linear configuration. 
     
     
         17 . The method of  claim 14 , wherein the proximal retention structure includes a coil portion, the disposing a proximal retention structure includes uncurling at least a portion of the coil portion. 
     
     
         18 . The method of  claim 14 , further comprising:
 placing a guidewire within the body of the patient.   
     
     
         19 . The method of  claim 14 , further comprising:
 placing the guidewire within a lumen defined by the medical stent.   
     
     
         20 . The method of  claim 14 , further comprising:
 placing at least a portion of the medical stent within a sheath.