Apparatus and methods for treating venous compression/obstruction syndromes

Abstract

Apparatus and methods are provided for treating patients exhibiting symptoms of hypertension, isolated systolic hypertension, heart failure with preserved ejection fraction, May-Thuner Syndrome or dyspnea by diagnosing and reducing narrowing of a patient's iliac vein caused by extrinsic localized compression using a stent having circumferential differential radial stiffness and delivery catheter for aligning and deploying such stents.

What is claimed: 
     
         1 . Apparatus for use in relieving an extrinsic localized compression of a patient's iliac vein, the apparatus comprising:
 a stent forming an elongated tube having a first end region, a second end region and a mid-region disposed therebetween, the elongated tube having a radial strength that varies as a function of circumferential angle only around the mid-region, the stent configured for placement in the patient's iliac vein and to transition between a contracted delivery state and an expanded deployed state; and   a delivery catheter for delivering the stent within the patient's iliac vein, the delivery catheter having sufficient rigidity to transmit a torque, applied at a proximal end of the catheter, to a distal end of the catheter to orient a selected portion of the mid-region of the stent to align with the extrinsic localized compression of the patient's iliac vein.   
     
     
         2 . The apparatus of  claim 1 , wherein the elongated tube comprises a plurality of struts. 
     
     
         3 . The apparatus of  claim 2 , wherein a geometric feature of the plurality of struts varies around a circumference of the elongated tube to produce the radial strength that varies as a function of circumferential angle around the mid-region. 
     
     
         4 . The apparatus of  claim 3 , wherein a geometric feature is selected from among: a length of the plurality of struts, a thickness of the plurality of struts or a shape of the plurality of struts. 
     
     
         5 . The apparatus of  claim 2 , wherein the plurality of struts includes a zig-zig shape or a serpentine shape. 
     
     
         6 . The apparatus of  claim 1 , wherein the stent is either self-expanding or balloon expandable. 
     
     
         7 . The apparatus of  claim 1 , wherein the delivery catheter comprises an elongated shaft having a proximal end and a distal region, the distal region configured to accept the stent in its contracted delivery state. 
     
     
         8 . The apparatus of  claim 7 , wherein the delivery catheter further comprises a sheath configured to be slidably disposed on the elongated shaft. 
     
     
         9 . The apparatus of  claim 7 , wherein the elongated shaft includes an array of radio-opaque markers configured to facilitate angular orientation of the stent within the patient's iliac vein prior to stent deployment, when viewed under fluoroscopic guidance. 
     
     
         10 . The apparatus of  claim 8 , wherein the sheath includes an array of radio-opaque markers configured to facilitate angular orientation of the stent within the patient's iliac vein prior to stent deployment, when viewed under fluoroscopic guidance. 
     
     
         11 . A stent configured for placement in the patient's iliac vein, the stent comprising:
 a plurality of longitudinal segments aligned along a common longitudinal axis to define a tube having a circumference, a first end region, a second end region, and a mid-region,   wherein the first end region is formed of a first plurality of interconnected struts having uniform mechanical properties around the circumference, and   wherein the second end region is formed of a second plurality of interconnected struts having uniform mechanical properties around the circumference, and   wherein the mid-region is formed of a third plurality of interconnected struts that spans a first arc of the circumference and a fourth plurality of interconnected struts that spans a second arc of the circumference, the third plurality of interconnected struts having different mechanical properties than the fourth plurality of interconnected struts.   
     
     
         12 . The stent of  claim 11 , wherein the uniform mechanical properties of the first plurality of interconnected struts are identical to the uniform mechanical properties of the second plurality of interconnected struts. 
     
     
         13 . The stent of  claim 11 , wherein the uniform mechanical properties of the first plurality of interconnected struts are different than the uniform mechanical properties of the second plurality of interconnected struts. 
     
     
         14 . The stent of  claim 11 , wherein the uniform mechanical properties of the first plurality of interconnected struts are identical to mechanical properties of the third plurality of interconnected struts. 
     
     
         15 . The stent of  claim 11 , wherein a geometric feature of the third plurality of struts is different than a same geometric feature of the fourth plurality of struts. 
     
     
         16 . The stent of  claim 15 , wherein the geometric feature is selected from among: a length of the plurality of struts, a thickness of the plurality of struts or a shape of the plurality of struts. 
     
     
         17 . The stent of  claim 11 , wherein any of the first, second, third and fourth pluralities of struts includes a zig-zig shape or a serpentine shape. 
     
     
         18 . The stent of  claim 11 , wherein the stent is either self-expanding or balloon expandable. 
     
     
         19 . The stent of  claim 11 , wherein the first end region or the second end region is configured to engage a delivery catheter that retains the stent in a contracted delivery state. 
     
     
         20 . The stent of  claim 11 , wherein a material property of the third plurality of struts is different than a same material property of the fourth plurality of struts.