Relationship of vascular remodeling and restenosis after interventional therapy: an experimental study on rabbit atherosclerotic iliac artery model.

OBJECTIVE: To evaluate the relative contribution of every part of vascular wall to lumen area loss after angioplasty. METHODS: Angioplasty was performed on rabbits iliac atherosclerosis model. Histomorphometric results of histological cross-sectional areas from target vessels of animals killed immediately after angioplasty (acute group, n = 20) were compared with those of the same areas from animals killed 4 weeks after the procedure (chronic group, n = 23), when restenosis occurred in this model. If taking 30% diameter decrease as restenosis criteria, the chronic group was further divided into two subgroups (nonrestenosis subgroup [NRS, n = 9] and restenosis subgroup [RS, n = 14]) and their histomorphometric results were also compared. RESULTS: The lumen area decreased by 0.48 mm2 from acute group to chronic group (acute group 0.86 +/- 0.23 mm2 vs chronic group 0.38 +/- 0.20 mm2, P < 0.001). Over the same period intimal area increased by 0.12 mm2 and the area circumscribed by inner elastic lamina (IEL area) decreased by 0.36 mm2. Intimal hyperplasia could only explain 25% of the later lumen area loss. We further found a more significant IEL area decrease in RS subgroup than in NRS subgroup (0.68 +/- 0.35 mm2 vs 0.94 +/- 0.14 mm2, P < 0.05), despite the same intimal area (0.39 +/- 0.16 mm2 vs 0.41 +/- 0.31 mm2, P = NS). The different lumen area between RS subgroup and NRS subgroup (0.27 +/- 0.10 mm2 vs 0.55 +/- 0.10 mm2, P < 0.001) was predominantly due to the greater IEL shrinking in RS subgroup. CONCLUSION: Our data indicate that later lumen area loss after angioplasty results from both intimal hyperplasia and arterial shrinking (remodeling), but the latter plays a much greater role.