Photodynamic therapy for atherosclerotic stenoses in Yucatan miniswine

To determine the feasibility of treating atherosclerotic stenoses with photodynamic therapy (PDT). A prospective study with a 4-week follow-up. Twelve Yucatan miniswine, weighing between 25 and 35 kg. Aortoiliac atherosclerosis was created by a combination of balloon endothelial injury and dietary supplementation with 2% cholesterol and 15% lard for 7 weeks. Then the miniswine were given a porphyrin-type photosensitizer (Photofrin), 2.5 mg/kg intravenously, and treated with 630 nm light through an intravascular, cylindrical, diffusing fibreoptic probe, which was coupled to an argon-pumped dye laser to supply 120 J of laser energy. Differences in luminal narrowing before and after PDT. Seven miniswine had an increase in luminal diameter, but five had no increase. Microscopy demonstrated a broad range of features in treated vessels, including areas with re-endothelialization and regions of platelet and blood cell adherence with absent or abnormal endothelium. Although this study demonstrated resolution in stenoses for some miniswine, questions concerning light dosimetry, mechanism of action and long-term effects remain to be determined.