Abstract: A stent (1) for deployment in a blood vessel which is movable between an unloaded straight cylindrical state and a loaded curved state. The stent (1) is bendable between a first loaded configuration when the blood vessel is in the unloaded state, and a second loaded configuration when the blood vessel is in the loaded state. The stent (1) has an unloaded configuration which is intermediate the first loaded configuration and the second loaded configuration. Because of the unloaded configuration of the stent (1), the degrees of deformation which the stent (1) undergoes are minimized leading to minimized strains, increased fatigue life, and reduced risk of fracture.

Abstract: A stent (1) comprises a central section (2), a first intermediate section (3), a first end section (4), a second intermediate section (5), and a second end section (6). The stent (1) is movable between a collapsed delivery configuration and an expanded deployment configuration. In the delivery configuration the central section (2), the first intermediate section (3), the first end section (4), the second intermediate section (5), and the second end section (6) are all cylindrically shaped. In the deployment configuration the central section (2) is helically shaped, while the first end section (4) and the second end section (6) remain cylindrically shaped. Each intermediate section (3, 5) acts as a blended region to provide a smooth transition from the helical shape of the central section (2) to the cylindrical shape of the unstented blood vessel. The radial stiffness of the stent (1) varies gradually along part of the length of the stent (1).