| abstract |
The present invention is directed to an expandable stent which is relatively flexible along its longitudinal axis to facilitate delivery through tortuous body lumens, but which is stiff and stable enough radially in an expanded condition to maintain the patency of a body lumen such as an artery when implanted therein. The struts of the present invention have a specific trapezoidal, triangular or a reduced radii configuration projecting radially outward that functions to reduce the forces necessary to penetrate the vessel wall thereby minimizing trauma or damage imparted to the wall during deployment. In addition, this design feature of the present invention helps secure the expanded stent so that it does not move once it is implanted and furthermore, minimizes projections into the blood stream. n The invention generally includes a plurality of radially expandable loop elements which are relatively independent in their ability to expand and to flex relative to one another. The individual radially expandable elements of the stent are dimensioned to minimize the strut from twisting or rotating during expansion. Interconnecting elements or a backbone extends between the adjacent loop elements to provide increased stability and a preferable position for each loop to prevent warping of the stent upon the expansion thereof. The resulting stent structure is a series of radially expandable loop elements which are spaced longitudinally close enough so that the obstruction, vessel wall and any small dissections located at the treatment site of a body lumen may be dilated or pressed back into position against the lumenal wall. n The manufacturing process of the present invention utilizes optimized stress-strain curve characteristics to achieve, unlike other non-wire stent designs, improved mechanical properties throughout the stent. The optimized stress-strain curve of the materail increases both the yield strength and the ultimate tensile strength of the expanded stent, increasing its resistance to structural failure (fracture) or stent crushing. |