Repeat dilation of Palmaz stents in pulmonary arteries: study of safety and effectiveness in a growing animal model

J Vasc Interv Radiol. 1994 May-Jun;5(3):425-32. doi: 10.1016/s1051-0443(94)71520-7.


Purpose: This study assessed the technical feasibility and safety of repeat dilation of Palmaz stents in growing pulmonary arteries.

Materials and methods: Palmaz stents (1.2 cm long) were placed percutaneously into the pulmonary arteries of 20 newborn lambs. After 4 months, pulmonary arteriography was performed. Where vessel growth in excess of stent diameter had created a stenosis (> 15%), stents were dilated again percutaneously. Six months later, pulmonary arteriography was performed, before the animal was killed and histologic examination performed.

Results: Twenty-four pulmonary artery stent placements were attempted; 23 were successful. One stent placement was unsuccessful owing to stent displacement from the balloon. Acute complications included branch pulmonary artery occlusion (n = 3) and stent displacement from the delivery balloon (n = 2). At 4 months, the desired degree of stenosis (> 15%) was achieved in 11 animals. The average stenosis was 35% (standard deviation, 16%; range, 17%-66%). The mean predilation stent diameter was 6 mm +/- 1.1 (range, 4-8 mm), and the final diameter of 8 mm +/- 1.4 (range, 6-10 mm), represented a 35% mean increase (P < .001). Complications included stent (n = 1) and branch vessel (n = 1) thrombosis. At 6-month follow-up, all stents were patent. Areas of previously noted branch thrombosis were fully recanalized in all cases. At histologic inspection, only a thin layer of neointima was found on the stents.

Conclusion: Repeat dilation of Palmaz stents may be safely performed in growing pulmonary arteries in an animal model. Neointimal hyperplasia is minimal in pulmonary artery stents.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Catheterization*
  • Constriction, Pathologic / diagnostic imaging
  • Constriction, Pathologic / pathology
  • Constriction, Pathologic / therapy
  • Equipment Design
  • Feasibility Studies
  • Hyperplasia
  • Pulmonary Artery* / diagnostic imaging
  • Pulmonary Artery* / growth & development
  • Pulmonary Artery* / pathology
  • Radiography
  • Sheep
  • Stents*
  • Tunica Intima / pathology