Auxetic stents for managing venous stenosis
Stents useable for treating venous stenosis are disclosed. In embodiments, a stent is configured to be auxetic, expanding axially as it is expanded radially, to prevent the imposition of tension on portions of a blood vessel adjacent to the stented portion of the blood vessel, and thereby prevent a narrowing of the adjacent portions and improving luminal gain. The stent may include one or more cross members that are deformable axially, to allow the axial length of the stent to be adjusted while maintaining a constant diameter, and further to allow the stent to be curved to conform to vessel curvature.
1 . A method for controlling a stenosis in a bodily duct, comprising:
inserting an apparatus having a plurality of cells arranged in a tubular configuration into a portion of the duct that is partially or wholly obstructed defining a stented portion of the duct and an adjacent portion of the duct that is not stented; and
expanding the apparatus radially to a predetermined diameter that relieves the duct of obstruction and longitudinally to engage with a wall of the duct and longitudinally expand the duct wall,
wherein the apparatus imparts a longitudinal elongation force on the duct wall during expansion placing the duct wall under tension,
wherein the apparatus longitudinally expands the duct wall within the stented portion until the tension in the duct wall is balanced with the longitudinal elongation force imparted by the apparatus, while the apparatus reduces strain on the duct wall within the adjacent portion of the duct,
wherein expansion of the apparatus increases a luminal volume of the duct, and
wherein the apparatus and the duct wall expand longitudinally as the apparatus's diameter is increased.
2 . The method of claim 1 , wherein the duct is one of, or a portion of one of, a biliary duct, a urogenital tract, a gastrointestinal tract, a tracheobronchial structure, a sinus tract, a salivary gland, a salivary tubule, a lymphatic channel, a surgical enterostomy, a surgical arteriovenous fistula or graft, a surgical anastomosis of at least two bodily structures, or an artery.
3 . The method of claim 1 , further comprising longitudinally expanding or compressing the apparatus to a predetermined length while maintaining the predetermined diameter.
4 . The method of claim 1 , further comprising longitudinally expanding or compressing a first portion of the apparatus to a different length than a second portion of the apparatus to place the apparatus in a curved configuration.
5 . The method of claim 1 , further comprising radially compressing the apparatus prior to inserting the apparatus.
6 . The method of claim 5 , wherein the apparatus is configured to plastically deform when below a predetermined temperature, and return to a non-deformed shape when above the predetermined temperature, and the apparatus is radially compressed prior to insertion below the predetermined temperature.
7 . The method of claim 6 , wherein the predetermined temperature is below 37 degrees C.
8 . The method of claim 1 , wherein each cell comprises:
a first member and a second member, each of the first member and second member further comprised of a flexible junction, each flexible junction dividing its respective member into a first segment with a first segment end and a second segment with a second segment end, each of the first and second segment ends distal from their respective flexible junction;
a cross member with a first end connected to the first segment of the first member proximate to the first segment end of the first member and a second end, distal from the first end, connected to the first segment of the second member proximate to the first segment end of the second member, wherein the cross member is connected to each first segment distal from each member's flexible junction;
a first joining member connected to the second segment of the first member proximate to the first member's flexible junction; and
a second joining member connected to the second segment of the second member proximate to the second member's flexible junction.
9 . The method of claim 1 , wherein the apparatus comprises a cellular arrangement of a plurality of struts, wherein the struts have a width oriented perpendicularly to the duct wall when the apparatus is in use in the duct, and a thickness oriented parallelly to the duct wall when the apparatus is in use in the duct, wherein the width of the struts is greater than the thickness of the struts.
10 . The method of claim 1 , wherein the apparatus includes a surface contact feature to enhance engagement of the apparatus with the duct wall to transmit force generated from longitudinal expansion of the apparatus to the longitudinal elongation force on the duct wall.
11 . The method of claim 10 , wherein the surface contact feature comprises one or more barbs protruding from the apparatus to contact the duct wall.
12 . The method of claim 10 , wherein the surface contact feature comprises a roughened or textured surface of the apparatus to enhance contact of the apparatus with the duct wall.
13 . The method of claim 1 , wherein the apparatus comprises:
a first member and a second member defining a cell, each of the first member and the second member comprising a flexible junction, each flexible junction dividing each respective member into a first segment with a first segment end and a second segment with a second segment end, the first and the second segment ends distal from the flexible junction; and
a cross member with a first end connected to the first segment of the first member and a second end, distal from the first end, connected to the first segment of the second member, wherein the cross member is connected to each first segment closer to, but spaced from, each first segment's first segment end than from each member's flexible junction.
14 . The method of claim 1 , wherein the apparatus comprises:
a first member and a second member defining a cell, each of the first member and the second member comprising a flexible junction, each flexible junction dividing each respective member into a first segment with a first segment end and a second segment with a second segment end, the first and the second segment ends distal from the flexible junction; and
a cross member with a first end connected to the first segment of the first member and a second end, distal from the first end, connected to the first segment of the second member, wherein the cross member is connected to each first segment at an acute angle forming a curved bend.