Chronological Changes in Morphometry and Histology in the Rabbit Vascular Wall after External Radiation for the Prevention of Intimal Hyperplasia

After arterial injury, external irradiation at 20 Gy effectively reduced aortic neointimal thickening. Irradiation-induced histological changes include recasting with rapid necrosis and delayed fibrosis. Radiation-induced parietal recasting with necrosis, fibrosis, and calcifications might worsen in time. Although irradiation after arterial injury leaves proliferative smooth-muscle cells within the arterial wall quantitatively unchanged in the early days after the procedure, it then induces a delayed reaction (observed over 45 days in our study). Whether neointimal hyperplasia is merely delayed or will ultimately develop causing restenosis awaits confirmation from experimental and clinical studies with a long-term follow-up.