Prevention of intimal hyperplasia

Objective

Endovascular brachytherapy, delivered by a variety of catheter-based devices, has proven clinically effective for the inhibition of neointimal hyperplasia (NIH) after coronary and peripheral balloon/stent angioplasty. No platform, however, has been developed to deliver low-dose radiation in concert with vascular surgical operations. The purpose of this study was to evaluate the vascular response following balloon injury to the rabbit carotid artery, with and without topical low-dose ⁴⁵Ca, applied by an external vascular “wrap”.

Methods

Twelve rabbit carotid arteries were subjected to balloon injury by embolectomy catheter. The common carotid artery was then “wrapped” circumferentially with a biostable polyurethane membrane (Nanoskin Secant Medical, Perkasie, PA), without radiation (n=6), or with radiation (n=6) (⁴⁵Ca ∼50 μCi). The animals were sacrificed at 4 weeks for histologic assessment of the treated vessels.

Results

The ⁴⁵Ca wrap inhibited NIH evidenced by trends towards reduction of intimal area (0.46±0.19 control carotid vs. 0.35±0.15 ⁴⁵Ca-treated carotid arteries; P=.11), maximal intimal thickness (0.21±0.08 vs. 0.16±0.05; P=.12), average intimal thickness (0.12±0.06 vs. 0.08±0.03; P=.08), marginally significant reduction in percent area stenosis (33±15% vs. 21±9%; P=.06) and marked neointima suppression in areas immediately adjacent to ⁴⁵Ca wrap remnants. Medial necrosis (P=.003), however, was observed slightly more for ⁴⁵Ca-treated carotid arteries versus control arteries.

Conclusion

Low-dose ⁴⁵Ca beta-radiation labeled onto a polyurethane membrane appears to inhibit NIH in an animal model.