Lipid rich, soft plaques in the clinic are a common forerunner to occlusive
thrombus formation, even with modest arterial
stenosis. Animal models of
atherosclerosis, obtained by various methods, do not generally allow direct in vivo evaluation of the lesion and, furthermore, cannot be examined more than once. The aim of the study was the generation of a rabbit model of
atherosclerosis, with morphological characteristics similar to human
lipid-rich, soft
atheromatous plaques, and the evaluation of the reliability of intravascular ultrasound (IVUS) technology in the study of the development of atherosclerotic lesions in this model. Briefly, New Zealand white rabbits undergo perivascular electrical injury at both common carotid arteries, together with a 1.5%
cholesterol diet for up to 90 days. The lesioned arterial segments show progressive changes, from diffuse cellular mortality, to macrophage infiltration in the media, up to the final migration of macrophages to the
neointima, resulting in bulky, eccentric, macrophage and
lipid-rich lesions. At IVUS, the produced lesions clearly resemble those described as 'soft plaques' in the clinical setting, with minimal calcification and reduced echo-reflectivity versus the adventitial layer. Quantitative and morphometric analysis of plaques shows a significant correlation between histological and IVUS measurements at each time point. In conclusion,
vascular injury in the common carotids of rabbits generates atherosclerotic
lipid-rich, soft plaques, that can be properly assessed by the IVUS methodology. The easy accessibility of the arterial lesion allows serial IVUS investigations and the direct evaluation of a number of locally or generally delivered therapeutic agents.