Acute effects of transluminal angioplasty in three experimental models of atherosclerosis

Abstract

Transluminal angioplasty has shown promise as a nonoperative treatment of atherosclerotic obstruction. Despite its increasing clinical use and potential importance, little is known of its mechanism and acute effects. To evaluate transluminal angioplasty, three rabbit models of experimental atherosclerosis were developed: Group 1 (n=20) = high cholesterol diet plus balloon de-endothelialization; Group 2A (n=12) = high cholesterol diet plus an indwelling catheter; Group 2B (n=10) = normal diet plus an indwelling catheter. After 6 weeks or 8 weeks, distinct angiographic and pathological lesions in the iliac artery were evident in all groups. Group 1 showed predominant foam cell lesions, while Group 2 showed eccentric mixed fibrous and foam cell or only fibrous lesions. Significant angiographic stenosis was present in 78% of the animals. Angioplasty of the highest grade iliac stenosis resulted in at least a 20% reduction in luminal diameter narrowing in 26 of 37 animals (70%). Histopathological examination 1 day following angioplasty in 17 animals showed two patterns. In Group 1 animals, neointimal fracture and dissection were evident, while in Group 2 animals thinning and stretching of the nonatherosclerotic portion of the vessel walls could be demonstrated. This study demonstrates that the New Zealand rabbit can be used to produce a spectrum of morphologically distinct atherosclerotic lesions that lend themselves to the study of transluminal angioplasty. The immediate consequences of angioplasty, which appear to depend upon the underlying histopathology and widening of the narrowed lumen, are frequently concurrent with intimal fracture, dissection, or thinning of the nonatherosclerotic portion of the vessel wall.