Analysis of solid phase debris from laser angioplasty: Potential risks of atheroembolism

Abstract

Laser energy can vaporize biologic tissues, and this unique method of ablation has been considered for the disobstruction of the occlusive lesion in atherosclerotic disease. To assess the potential embolic sequelae from laser angioplasty, solid phase debris (SPD) was analyzed. Specimens of human cadaver aorta were subjected to standardized argon laser injury, and SPD was quantified by weight in four types of ablated tissue: normal aortic intima, fatty streaks, fibrous plaque, and calcified plaque (CP). The debris by weight of tissue ablated was significantly higher for CP (p < 0.05), measuring 7.9%, whereas normal aortic intima, fatty streaks, and fibrous plaque yielded 3.2%, 2.7%, and 3.7%, respectively. Likewise, the amount of debris liberated per unit volume of albated tissue was greatest for CP averaging 156 mg/cc. Light and scanning electron microscopy of SPD revealed carbonized tissue particles up to 350 μm from all classes and cholesterol crystals up to 250 μm from CP. SPD from CP was infused into renal arteries of rats at two dosages, 4 and 16 mg, to observe effects on end-organ tissue. At 10 days, all kidneys demonstrated focal ischemic atrophy and recovering acute tubular necrosis in a dose-dependent fashion (p < 0.05). Control rats showed no disease. Kidneys embolized with SPD also displayed foreign body granulomas (9 of 12), periarterial inflammation (11 of 12), and cortical wedge infarcts (10 of 12). Argon laser energy that ablates tissue predominantly by thermal mechanisms liquified or vaporized 96% to 97% of noncalcified atheromatous material. Laser ablation of CP, however, liberated significantly more SPD. The ischemic and inflammatory injuries caused by embolization of SPD were identical with the classic descriptions of atheroembolism.