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.

A stent for insertion into a vessel of a patient includes an inner tube comprising a positive Poisson's ratio (PPR) material and defining a lumen extending along a longitudinal axis of the stent; and an outer tube comprising a negative Poisson's ratio (NPR) foam material and disposed around an entirety of the inner tube, the outer tube extending along the longitudinal axis of the stent. The stent is configured to exhibit an auxetic behavior in response to a deformation of the stent. An outer surface of the second portion is configured to apply a pressure to an inner surface of the vessel when the stent is implanted into the vessel and the deformation is removed.

An atrioventricular prosthesis device is provided. The device includes a frame at least partially defining and enclosing a central cavity, the frame having a distal portion, a proximal portion, and a middle portion connected therebetween. The device further includes a valve construct formed, at least in part, from a cell growth scaffold, at least partially disposed within the central cavity defined by the frame. The valve construct includes: an annular portion defining an aperture and being connected to the frame for positioning the valve construct within the central cavity of the frame, and a plurality of leaflets extending longitudinally and radially inward from the annular portion. The frame and valve construct are transitionable to a deployed state, in which a diameter of at least a portion of the frame and the valve construct substantially conform to a diameter of a tricuspid and/or mitral valve opening.