PREVENTING INTIMAL HYPERPLASIA WITH PHOTODYNAMIC THERAPY USING AN INTRAVASCULAR PROBE

The purpose of this study was to determine the efficacy of intravascul ar photodynamic therapy (PDT) to prevent the development of intimal hy perplasia. Anesthetized New Zealand white rabbits underwent placement of Fogarty balloon catheters introduced via femoral artery cutdowns. C atheters were passed retrograde 10 cm into the lower abdominal aorta, inflated six times, and withdrawn toward the inguinal ligament. Rabbit s were then randomly assigned to one of the following groups: group 1, drug with no light; group 2, no drug with 240 joules of light; group 3, drug plus 120 joules of light; or group 4, drug plus 240 joules of light. Uninjured carotid arteries served as negative control vessels ( N) and injured but non-PDT-treated iliac artery segments served as pos itive controls (P). Porfimer sodium (Photofrin) was administered in a dose of 5.0 mg/kg. Light was provided by a fiberoptic probe with a 1 c m cylindric diffuser attached to an argon pumped dye laser tuned to 63 0 nm to provide 1 W of laser light for 120 or 240 seconds. One month a fter PDT, rabbits were killed, perfusion fixed with glutaraldehyde, an d vessels removed and examined microscopically. Intimal thickness (mea n +/- SD) was calculated and expressed as ratios of the intima/media a t four equal positions. Results for N, P, and groups 1, 2, 3, and 4 we re 0.02 +/- 0.00, 1.18 +/- 0.71, 0.76 +/- 0.33, 0.96 +/- 0.43, 0.14 +/ - 0.22, and 0.36 +/- 0.16, respectively. Intimal thickness was signifi cantly reduced in groups 3 and 4 when compared with P, group 1, and gr oup 2 (p < 0.001, ANOVA). These results showed that intravascular PDT was effective in reducing intimal hyperplasia following arterial injur y. This may be a practical method of delivering light for PDT.