A polyester intravascular stent for maintaining luminal patency: a gross and microscopic study of the device's incorporation, early maturation, and thrombogenicity.

Over the past 3 years, we have developed a polyester mesh stent designed to preserve luminal patency in cases of dissecting aortic aneurysm and to maintain arterial patency after angioplasty. To study the stent's incorporation into the aortic wall and to test its thrombogenicity, we implanted the device in the abdominal aortas of ten dogs. The device was compressed and inserted into a 10-Fr sheath, which was introduced through the femoral artery into the aorta. Once liberated from the sheath and fully expanded within the aorta, the stent measured 10 cm in length and 8 mm in outer diameter. Each animal was followed up clinically until it was killed at intervals ranging from 1 week to 6 months after implantation. The aorta was excised, and tissue incorporation was evaluated grossly, as well as with light and scanning electron microscopy. In all cases, the arteries and side branches were found to be widely patent. At 3 weeks, the stent already had become firmly adherent to the vessel, owing to the ingrowth of fibrous tissue and endothelium through the mesh. The thrombus-free surface area, assessed planimetrically, was minimal during the early part of the study but rose to a plateau of 80% by the second month. Each specimen was subjected to indium-111 platelet scanning. The polyester mesh initially stimulated much platelet deposition, but this phenomenon decreased markedly over a 2-month period. In summary, our experience showed that an intraluminal polyester mesh stent could be inserted into the aorta via the retrograde arterial route and could effectively line the inner surface of the vessel. Within 2 months, healing was nearly complete and thrombogenicity was minimal.