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). The radial stiffness of the end region of the stent (1) is less than the radial stiffness of a first region located further in from the end of the stent (1). The variation in radial stiffness reduces the area of blood vessel wall which has low wall shear stress, reduces the possibility of recirculation, and reduces the risk of neointimal hyperplasia.
