RESULTS: Thrombi of the auricular margin vein were formed and blood flow was obstructed after
PDT.
Thrombus formation and diffused
necrosis of adjacent tissue was found after injection of
sodium morrhuate. On ultrasonic examination, the lumina of the veins showed a slightly higher echo after
PDT compared with a lower echo before treatment, which was another sign of
thrombus formation. The rabbit ears showed a diffused low echo after injection of
sodium morrhuate, indicating diffuse
necrosis. On microscopic observation, destruction of the endothelium and formation of
thrombus was seen after
PDT. Further observation of specimens stained with
Victoria blue showed that the layer of elastic fiber was intact. After injection of
sodium morrhuate, extensive
necrosis of tissue was seen microscopically. No macroscopic, ultrasonic, or microscopic change was found in the rabbits that received irradiation only or injection of
photosensitizer only. The rate of
thrombus formation in rabbits that received
PDT was significantly higher than that in the rabbits that received irradiation only or injection of photosensitizor only ( P = 0.015, P = 0.015), and comparable to that in the rabbits that received
sclerotherapy ( P = 0.467). In the clinical study, at endoscopy 1 month after
PDT both the number and the "red sign" of newly visible veins were found to have decreased. No adverse effect was found.
CONCLUSION:
PDT can destroy the endothelium of the vein, result in
thrombus formation, and eventually obliterate the vein. It is potentially a new method for the treatment of
esophageal varices.