THE ATHEROSCLEROTIC YUCATAN ANIMAL-MODEL TO STUDY THE ARTERIAL RESPONSE AFTER BALLOON ANGIOPLASTY - THE NATURAL-HISTORY OF REMODELING

Objective: Remodeling in de novo atherosclerosis and in restenosis aft er balloon angioplasty constitutes a change in total arterial circumfe rence which, together with plaque growth or neointimal formation, dete rmines the lumen of the artery. To better understand the fundamental b iology of neointimal formation, remodeling and their interaction, anim al studies are needed. In this study, we described in detail the metho dology used and the natural history of neointimal formation and remode ling after balloon angioplasty in atherosclerotic Yucatan micropigs. M ethods and results: Atherosclerosis was induced in 60 peripheral arter ies of sixteen Yucatan micropigs by a combination of denudation and at herogenic diet. Balloon angioplasty was performed in 38 arteries, with serial intravascular ultrasound (IVUS) and quantitative angiography b efore and after intervention and at 2, 4, 7, 14 or 42 days follow-up. Remodeling, expressed as late media-bounded area (MBA) loss, increased progressively over time. At 42 days, late MBA loss after balloon angi oplasty was significantly different compared to late MBA loss in contr ol arteries, 2.2+/-1.0 versus -0.3+/-1.1 mm(2) and p = 0.02. Late lume n loss increased over time and was highest at 42 days after balloon an gioplasty (2.8+/-0.7 mm2). The contribution of neointimal formation to late lumen loss decreased over time and the contribution of late MBA loss to late lumen increased over time and was highest at 42 days (78% ). Medial necrosis was 48% at two days after balloon angioplasty and t he repopulation of the media was almost completed at seven days. Concl usion: Remodeling following balloon angioplasty has an early onset and progresses with neointimal formation to cause restenosis over the sta ndard 42-day time course for Yucatan micropigs. This correlates to six months renarrowing in humans. In this model, atherosclerosis and the natural history of restenosis, both with respect to neointimal formati on and remodeling, resemble the human disease quite closely. (C) 1998 Elsevier Science B.V. All rights reserved.