An expandable axially elongate stent comprising: a plurality of undulating ring elements configured to be expandable from an unexpanded condition to an expanded condition, the ring elements being positioned one adjacent to another along an axis, wherein, each ring element includes a plurality of struts having an orientation in relation to the axis and each strut connected to an adjacent strut by a curved elbow; and and each strut is connected to an adjacent strut by a curved elbow; and each curved elbow has a concave portion and a convex portion, further wherein, a first end zone of the stent includes a plurality of ring elements, not less than three in number, and each ring element in the first end zone is connected to an adjacent ring element in the first end zone by at least one connector extending from a convex portion of one ring to a convex portion of an adjacent ring; further wherein, a middle zone of the stent positioned adjacent the first end zone includes a plurality of ring elements, not less than three in number, and each ring element in the middle zone is connected to an adjacent ring element in the middle zone by at least one connector extending from a concave portion of one ring to a convex portion of an adjacent ring, and further wherein a second end zone of the stent includes a plurality of ring elements and each ring element in the second end zone is connected to an adjacent ring element in the second end zone by at least one connector extending from a concave portion of one ring to a concave portion of an adjacent ring, whereby the stent when expanded presents a gradually decreasing radial stiffness extending from said first end zone to said second end zone. a plurality of undulating ring elements configured to be expandable from an unexpanded condition to an expanded condition, the ring elements being positioned one adjacent to another along an axis, wherein, each ring element includes a plurality of struts having an orientation in relation to the axis and each strut connected to an adjacent strut by a curved elbow; and and each strut is connected to an adjacent strut by a curved elbow; and each curved elbow has a concave portion and a convex portion, further wherein, a first end zone of the stent includes a plurality of ring elements, not less than three in number, and each ring element in the first end zone is connected to an adjacent ring element in the first end zone by at least one connector extending from a convex portion of one ring to a convex portion of an adjacent ring; further wherein, a middle zone of the stent positioned adjacent the first end zone includes a plurality of ring elements, not less than three in number, and each ring element in the middle zone is connected to an adjacent ring element in the middle zone by at least one connector extending from a concave portion of one ring to a convex portion of an adjacent ring, and further wherein a second end zone of the stent includes a plurality of ring elements and each ring element in the second end zone is connected to an adjacent ring element in the second end zone by at least one connector extending from a concave portion of one ring to a concave portion of an adjacent ring, whereby the stent when expanded presents a gradually decreasing radial stiffness extending from said first end zone to said second end zone.