Variable depression stents (vds) and billowing graft assemblies

A stent assembly comprising:

• a first support ring having interconnected circumferentially alternating first inner prongs and first outer prongs, the first inner prongs defining a first inner diameter around a central longitudinal axis, and the first outer prongs defining a first outer diameter around the central longitudinal axis greater than the first inner diameter;
• a second support ring spaced from the first support ring along the central longitudinal axis, the second support ring having interconnected circumferentially alternating second inner prongs and second outer prongs, the second inner prongs defining a second inner diameter around the central longitudinal axis, and the second outer prongs defining a second outer diameter around the central longitudinal axis greater than the second inner diameter, wherein, in cooperation, a radially recessed portion of the first support ring and the second support ring defines at least one channel;
• a billowing graft engaging at least a portion of one or more of the first support ring and the second support ring, the billowing graft following a waving peripheral path and creating longitudinal grooves at least partially around the at least one channel of the first support ring and second support ring, wherein at least one of the longitudinal grooves extends in a direction that is parallel to a direction of a central axis extending along a length of the stent assembly.