The role of elastic recoil after balloon angioplasty of rabbit arteries and its prevention by stent implantation

Elastic recoil, neointima formation and vessel narrowing after balloon angioplasty or stent implantation were compared in 17 non-atherosclerotic New Zealand White rabbits. The implantation of a balloon-expandable Palmaz-Schatz stent was performed in one iliac artery and a balloon angioplasty alone was performed in the contralateral artery (n = 34 arteries). Quantitative histomorphometry was performed by a computer-assisted analysis 1 h and 4, 10 and 24 weeks after the initial procedure. The histological appearance of the neointima was similar to that of human restenosis. The amount of the neointima was increased within stented vessels as compared to balloon angioplasty alone (1.0 +/- 0.1 vs 0.4 +/- 0.1 mm2 at 4 weeks, P < 0.001). However, the neointimal lumen narrowing was smaller in the stented vessels due to persistent increase in vessel perimeter as compared to balloon angioplasty alone (16.5 +/- 0.9 vs 34.7 +/- 16.5% lumen narrowing at 4 weeks, P < 0.05). In conclusion, stent implantation enhances neointima formation as compared to angioplasty in non-atherosclerotic rabbits. The prevention of elastic recoil after stent implantation, however, reduces the neointimal lumen narrowing. This study supports clinical observations demonstrating lower restenosis rates after stent implantation compared to standard balloon angioplasty.