Objective: To determine the feasibility of treating atherosclerotic stenoses with photodynamic therapy (PDT).
Design: A prospective study with a 4-week follow-up.
Subjects: Twelve Yucatan miniswine, weighing between 25 and 35 kg.
Interventions: 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.
Main outcome measures: Differences in luminal narrowing before and after PDT.
Results: 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.
Conclusion: 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.