Endovascular irradiation with the liquid beta-emitter Rhenium-188 to reduce restenosis after experimental wall injury

Objective: Postinterventional irradiation is a new therapeutic concept in t he prevention of restenosis. The liquid beta -emitter Rhenium-188 allows en dovascular brachytherapy using a conventional balloon catheter without the problem of centering the radiation source. In an animal model of restenosis the feasibility and the dose dependent effect of intravascular brachythera py with a Rhenium-lss filled balloon catheter was investigated. Methods: In 68 male New Zealand White rabbits after endothelial denudation of the righ t common carotid artery with a Fogarty catheter, endovascular irradiation w as performed with a Rhenium-188 filled 3.0-mm balloon catheter using differ ent dosages (0, 7.5, 15, 30, 45 and 60 Gy at the surface of the vessel). Th en 4 weeks after the intervention the vessels were excised and histological ly analyzed. Results: Whereas at 7.5 Gy the intimal area (median [first qua rtile; third quartile]) did not differ significantly from the control (0.46 mm(2) [0.33 mm(2), 0.75 mm(2)] vs. 0.49 mm2 [0.34 mm(2), 0.66 mm(2)]), neo intimal hyperplasia was decreased significantly at 15 Gy (0.15 mm(2) [0.04 mm(2), 0.17 mm(2)]) and 30 Gy (0.07 mm(2) [0.04 mm(2), 0.10 mm(2)]), and co mpletely inhibited at the highest dosages (45 Gy: 0 mm(2) [0 mm(2), 0.04 mm (2)]; 60 Gy: 0 mm(2) [0 mm(2), 0.01 mm(2)]). Conclusions: Catheter transmit ted endovascular irradiation with the liquid beta -emitter Rhenium-lds afte r vascular injury is feasible and effectively reduced neointimal hyperplasi a in hypercholesterolemic rabbits. A significant reduction of the neointima l formation could be found already at a radiation absorbed dose of 15 Gy at the vessel surface. Following a surface dosage of 45 Gy the proliferative response to the vessel injury is almost completely abolished. (C) 2001 Else vier Science B.V. All rights reserved.