MATHEMATICAL FORMULATION FOR COMPUTING THE PERFORMANCE OF SELF-EXPANDING HELICAL STENTS

Stents are cylindrical devices implanted inside pathologic tubular pas sages within the body. The stents, which are made of metal or plastic, keep the passage open for flow (of blood, urine, air etc.) by applyin g radial pressure on the passage walls. In most cases the stents are s elected empirically for each application. We introduce here a mathemat ical formula for computing the radial pressure induced by self expandi ng helical stents. The formula was verified experimentally for an urol ogical stent using a special device. The results correlate well with t he theoretical predictions (R = 0.997; y = 1.017 x -0.06 kg; SEE = 0.0 34, for forces and R = 0.9988; y = 1.04 x +8.7 mmHg; SEE = 25.3 for pr essures). This formula can potentially serve as an analytical tool for selecting the most suitable stent for a given application. (C) 1997 E lsevier Science Ireland Ltd.