Endovascular treatment using low-power ultraviolet laser for delayed vasospasm in the rabbit carotid artery model.

BACKGROUND AND PURPOSE We previously reported that pretreatment with external ultraviolet (UV) irradiation at 325 nm before blood exposure prevented the development of chronic vasospasm in rabbit common carotid arteries. The purpose of this study was to investigate the preventive effect of endovascular UV light on vasospasm after blood immersion by using the same animal model. METHODS The right common carotid arteries in 63 rabbits were enclosed in silicon cuffs on day 0. Sheaths were empty or filled with clotted blood. Thirty minutes after the placement of the sheaths, either alone or with blood, the common carotid arteries were subjected to UV or visible light (442 nm) irradiation via an endovascular approach at a fluence rate of 0.17 W/cm(2). The animals were killed on day 2, 9, or 30. Digital subtraction angiography was performed on days 0 and 2 and at the end point to evaluate the degree of vasospasm. RESULTS UV treatment significantly prevented the development of vasospasm on day 2. On days 9 and 30, there were no significant differences between UV-treated animals and control animals. The preventive effect reached an approximate plateau with an irradiation time of 10 s. No severe vascular injury, such as perforation, occurred in response to UV treatment during the observation period. UV light was significantly more effective than visible light in preventing vasospasm (P <.001). CONCLUSION These results suggest that endovascular UV irradiation after blood exposure has a prophylactic effect on vasospasm and suggest a dependence on irradiation wavelength and duration of irradiation.