RESPONSE OF FEMORAL ARTERIES OF CHOLESTEROL-FED RABBITS TO BALLOON ANGIOPLASTY WITH OR WITHOUT LASER - EMPHASIS ON THE DISTRIBUTION OF FOAMCELLS

Very little is known about the structural composition of the restenoti c plaque in evolution. The responses of atherosclerotic femoral arteri es of rabbits to balloon angioplasty (BA), thallium/holmium/chromium:Y AG infrared laser angioplasty (LA), combined LA and BA, or no angiopla sty were compared by blinded quantitative histomorphometry and angiogr aphy. The endothelium was injured by nitrogen/air desiccation, and the animals were fed a 2% cholesterol diet for 1 month prior to the angio plasty procedure. Animals were sacrificed 2 hr or 28 days after angiop lasty by pressure perfusion with 10% formaldehyde (100 mm Hg), and art erial segments (4-5 cm) were excised bilaterally. The frequency of thr ombus was greatest in arteries with LA. Arteries with combined LA and BA had the greatest initial gain in luminal diameter by angiography, b ut they also had the greatest reduction in luminal diameter from 2 hr to 28 days and the greatest cross-sectional area narrowing by plaque a t 28 days. The principal component of the intimal plaques in all group s was fibrous tissue (approximately 90%), with the remainder consistin g primarily of ''foam cells. '' By multiple regression analysis, the s trongest predictors of cross-sectional area narrowing were contiguity of foam cells between the intima and media, depth of the tear, percent age of foam cells in the plaque, and the intervention of LA followed b y BA. The principal predictors of foam cells in the plaque, irrespecti ve of treatment, were also cross-sectional area narrowing, contiguity of foam cells between plaque and media, and the depth of tear. It is s uggested that a large proportion of the foam cells of the intima may b e derived from foam cells of the media and adventitia rather than from the lumen. These observations may be of particular importance regardi ng angioplasty in young people where foam cells occupy a significantly greater proportion of the atherosclerotic plaque. (C) 1993 Academic P ress, Inc.