CHARACTERIZATION OF PULSED-DYE LASER-MEDIATED VASODILATATION IN A RABBIT FEMORAL-ARTERY MODEL OF VASOCONSTRICTION

Vasoconstriction is a clinical problem associated with invasive vascul ar procedures, microvascular reconstruction and subarachnoid hemorrhag e. We sought to characterize the ability of pulsed-dye laser irradiati on to reverse and prevent vasoconstriction in an anesthetized rabbit m odel of surgically and pharmacologically induced vasoconstriction. Fiv e groups of experiments were performed to study the effect of pulsed-d ye laser irradiation delivered through a 320 mum core ball-tip fiber i nto the femoral artery. The studies demonstrated that pulsed-dye irrad iation can reproducibly cause vascular dilatation. The zone of vasodil atation propagated equally proximal and distal to the site of irradiat ion within the vessel. When saline was infused into the vessel to repl ace flowing blood during delivery of laser irradiation, no significant vasodilatation occurred. After laser irradiation reversed surgical an d pharmacologic vasoconstriction, the vessel was resistant to further pharmacologic vasoconstriction. This resistance to pharmacologic vasoc onstriction did not occur if the vessel was pharmacologically predilat ed before delivery of laser irradiation. Pathologic analysis of the ve ssels revealed endothelial damage and mild to moderate medial necrosis , most significant at the site of energy delivery. These studies provi de characterization of pulsed-dye laser-mediated vasodilatation in an in vivo model. Delivery of pulsed- dye laser energy has potential clin ical application and warrants further investigation.