A system for delivering and placement of a medical prosthesis into an ostium of a tract system of an organism is described. The system comprises a stent delivery device that includes a delivery catheter having one or more lumens extending between proximal and distal ends. The stent delivery device also includes an inflatable balloon mounted on the distal end of the delivery catheter for expanding and deploying the medical prosthesis placed on the balloon, and a stent deployment site locator configured for locating an exact place for positioning the medical prosthesis. The deployment site locator comprises an expandable flexible structure including a plurality of filament elements interconnected between a locator proximal end and a locator distal end; thereby forming a unitary structure. The filaments can extend from a locator proximal end towards a locator distal end and then return after winding to the proximal end to form a plurality of filament loops.
