Development of a reexpandable covered stent for children.

The use of covered stents in children is limited by the need for a large long sheath for delivery and the impossibility of redilation once implanted. The authors developed a reexpandable covered stent implantable in children through a small sheath and evaluated its clinical feasibility in mini piglets. An original Palmaz stent was covered with a polyurethane membrane that could be stretched up to 700%. Under general anesthesia, the authors implanted the covered stents in six mini piglets using a long sheath with a diameter approximately 1 French larger than the recommended size required to deliver an uncovered Palmaz stent. The implantation technique was similar to conventional stent implantation. In six piglets, the stent could be redilated from 7.5 to 8.7 mm 28-70 days after implantation. Macroscopic and microscopic examination showed intimal coverage of the coating with minimal inflammatory reaction around the stent. Our newly designed reexpandable stent covered with a polyurethane membrane is promising for use in children.