Self-expanding metallic stents for small vessels: an experimental evaluation.

Thirty-three self-expanding metallic stents were placed in 24 arterial segments of the hind legs and nine arteries of the abdominal viscera in seven dogs. Twelve 5-mm stents, eight 4-mm stents, and 13 3-mm stents were inserted. Follow-up ranged from 4 to 30 weeks. All 4-mm and 5-mm stents were patent at follow-up. Seven (54%) of the 3-mm stents remained patent. Stent wires were completely covered by a proliferation of the intima. No stent migration, occlusion of side branches, or vessel wall perforation was observed. A stent/artery ratio (SAR) was computed using stent and recipient vessel diameters. Good vascular patency was observed when the SAR was less than or equal to 1.2. An SAR greater than 1.2 was associated with immediate spasm, immediate or delayed thrombosis, or excessive intimal proliferation. Selection of correct stent size is a major determinant of patency in small arteries.