Patent ID: 7334609

Claim:
A flexible, tubular metal device with an internal diameter up to 60 millimeters, the device comprising a metal wall in which are formed one or more nonhelical corrugated convolutions that define a nonhelical corrugated outside surface of the device and a nonhelical corrugated inside surface of the device, each of the convolutions having rounded radially-outward portions and rounded radially-inward portions axially adjacent each other, the outside surface defined by each convolution of the device having first and second sections with change positions therebetween, the first section of each convolution extending from one of the change positions to another of the change positions via one of the radially-outward portions, the second section of each convolution extending from one of the change positions to another of the change positions via one of the radially-inward portions, the length of each of the first sections being at least 10% longer than the length of each of the second sections, the outside surface of each convolution having a non-constant curvature derived from a curve that is continuous in the first and second sections and defined by the intersection of the outside surface and a plane through the longitudinal axis of the device, the curvature of the outside surface being numerically smaller at each of the radially-outward portions than at each of the radially-inward portions, the curve within each of the first sections having one global maximum located within the radially-outward portion thereof, the curve within each of the second sections having a global minimum located at the radially-inward portion thereof, the curvature of the curve changing sign only once at each of the change positions.