Linearly expandable ureteral stent

Abstract

A ureteral stent including an elongated member defining a lumen, the member having a solid sidewall defining a spiral-shaped opening such that the member is linearly expandable along a longitudinal axis of the lumen. A distal retention structure is connected to a distal end of the elongated member for retention in a kidney. A proximal retention structure is connected to a proximal end of the elongated member for retention in a bladder.

What is claimed is:  
     
         1 . A ureteral stent comprising: 
 an elongated member defining a lumen, the member having a solid sidewall defining a spiral-shaped opening such that the member is linearly expandable along a longitudinal axis of the lumen;    a distal retention structure connected to a distal end of the elongated member for retention in a kidney; and    a proximal retention structure connected to a proximal end of the elongated member for retention in a bladder.    
     
     
         2 . The stent of  claim 1  wherein the member comprises a spring having a spring force of less than one pound.  
     
     
         3 . The stent of  claim 2  wherein the member comprises a wire spring.  
     
     
         4 . The stent of  claim 3  wherein the wire spring comprises a metal alloy.  
     
     
         5 . The stent of  claim 4  wherein the metal alloy comprises at least one of titanium, nickel, copper, cobalt, vanadium, and iron.  
     
     
         6 . The stent of  claim 5  wherein the metal alloy comprises nitonol.  
     
     
         7 . The stent of  claim 6  wherein nitonol comprises nickel and titanium.  
     
     
         8 . The stent of  claim 7  wherein nitonol comprises about 50% to about 52% nickel.  
     
     
         9 . The stent of  claim 8  wherein nitonol comprises about 48% to about 50% titanium.  
     
     
         10 . The stent of  claim 3  wherein the wire spring is coated with a polymer.  
     
     
         11 . The stent of  claim 10  wherein the polymer comprises at least one of urethane, nylon, thermoplastic polyurethane (TPU), thermoplastic polyester elastomer, polyethyl, and silicone.  
     
     
         12 . The stent of  claim 1  wherein the elongated member comprises a tube having the solid sidewall and defining the lumen, and the spiral-shaped opening is defined by a slit formed in the sidewall of the tube.  
     
     
         13 . The stent of  claim 12  wherein the elongated member comprises a polymer.  
     
     
         14 . The stent of  claim 13  wherein the polymer comprises at least one of urethane, nylon, thermoplastic polyurethane (TPU), thermoplastic polyester elastomer, polyethyl, and silicone.  
     
     
         15 . The stent of  claim 1  wherein the elongated member comprises an inner liner and an outer cover.  
     
     
         16 . The stent of  claim 15 , further comprising: 
 a wire spring sandwiched between the inner liner and the outer cover,    wherein the spiral-shaped opening is defined by slits formed in the inner liner and the outer cover, between a plurality of coils of the wire spring.    
     
     
         17 . The stent of  claim 16  wherein the wire spring comprises a metal alloy.  
     
     
         18 . The stent of  claim 17  wherein the metal alloy comprises at least one of titanium, nickel, copper, cobalt, vanadium, and iron.  
     
     
         19 . The stent of  claim 17  wherein the metal alloy comprises nitonol.  
     
     
         20 . The stent of  claim 19  wherein nitonol comprises nickel and titanium.  
     
     
         21 . The stent of  claim 15  wherein at least one of the inner liner and the outer cover comprises a polymer.  
     
     
         22 . The stent of  claim 21  wherein the polymer comprises at least one of urethane, nylon, thermoplastic polyurethane (TPU), thermoplastic polyester elastomer, polyethyl, and silicone.  
     
     
         23 . The stent of  claim 1 , further comprising: 
 a removable introducer sized for placement within the lumen.    
     
     
         24 . A ureteral stent comprising: 
 an elongated member defining a lumen, the member having a solid sidewall with at least one slit formed therein such that the member is linearly expandable along a longitudinal axis of the lumen;    a distal retention structure connected to a distal end of the elongated member for retention in a kidney; and    a proximal retention structure connected to a proximal end of the elongated member for retention in a bladder.    
     
     
         25 . A method of facilitating urinary drainage from a kidney to a bladder in a patient that reduces discomfort to the patient, comprising: 
 positioning a ureteral stent in a ureter of a patient, the ureteral stent having an elongated member defining a lumen, the member having a solid sidewall defining a spiral-shaped opening such that the member is linearly expandable along a longitudinal axis of the lumen, a distal retention structure connected to a distal end of the elongated member for retention in the kidney, and a proximal retention structure connected to a proximal end of the elongated member for retention in the bladder; and    allowing the elongated member to linearly expand and contract between an expanded position and a retracted position, based on at least one of: relative positioning of organs within the patient, a breathing pattern of the patient, and relative positions of the kidney and the bladder.    
     
     
         26 . The method of  claim 25  wherein the organs comprise the kidney and the bladder.  
     
     
         27 . The method of  claim 25  wherein the organs are the kidney and the bladder.  
     
     
         28 . The method of  claim 25  wherein the allowing step comprises providing the elongated member biased to the retracted position.  
     
     
         29 . A method of manufacturing a linearly expandable ureteral stent, comprising the steps of: 
 providing an elongated member defining a lumen, the member having a solid sidewall defining a spiral-shaped opening such that the member is linearly expandable along a longitudinal axis of the lumen, a distal retention structure, and a proximal retention structure;    connecting the distal retention structure to a distal end of the elongated member; and    connecting the proximal retention structure to a proximal end of the elongated member.    
     
     
         30 . The method of  claim 29  wherein providing the elongated member comprises providing a wire spring.  
     
     
         31 . The method of  claim 30  wherein providing the wire spring comprises coating the wire spring with a polymer.  
     
     
         32 . The method of  claim 30  wherein providing the wire spring comprises sandwiching the wire spring between an inner lining and an outer cover.  
     
     
         33 . The method of  claim 32  wherein the inner lining and outer cover comprise extruded sheets.  
     
     
         34 . The method of  claim 32 , further comprising; 
 shrinking the inner lining and outer cover; and    forming slits through the inner lining and outer cover between a plurality of coils of the wire spring.    
     
     
         35 . The method of  claim 32 , further comprising: 
 melting the inner lining and the outer cover; and    forming slits through the inner lining and outer cover between a plurality of coils of the wire spring.    
     
     
         36 . The method of  claim 29  wherein providing the elongated member comprises forming a tube comprising a polymer and forming a spiral slit through the tube.  
     
     
         37 . A method of placing a ureteral stent in a patient, the method comprising: 
 providing a ureteral stent comprising: 
 an elongated member defining a lumen, the member having a solid sidewall defining a spiral-shaped opening such that the member is linearly expandable along a longitudinal axis of the lumen;  
 a distal retention structure connected to a distal end of the elongated member; and  
 a proximal retention structure connected to a proximal end of the elongated member;  
   inserting the ureteral stent into a ureter of the patient; and    positioning the ureteral stent in the patient with the distal retention structure substantially within the kidney of the patient, the elongated member substantially within the intramural tunnel portion of the ureter, and the proximal retention structure substantially within the bladder of the patient.    
     
     
         38 . The method of  claim 37  wherein the ureteral stent further comprises a removable introducer sized to fit within the lumen and inserting the ureteral stent includes inserting the stent with the removable introducer into the ureter.