Characterization of pulsed‐dye laser‐mediated vasodilatation in a rabbit femoral artery model of vasoconstriction

Abstract

Vasoconstriction is a clinical problem associated with invasive vascular procedures, microvascular reconstruction and subarachnoid hemorrhage. We sought to characterize the ability of pulsed-dye laser irradiation to reverse and prevent vasoconstriction in an anesthetized rabbit model of surgically and pharmacologically induced vasoconstriction. Five groups of experiments were performed to study the effect of pulsed-dye laser irradiation delivered through a 320 microns core ball-tip fiber into the femoral artery. The studies demonstrated that pulsed-dye irradiation can reproducibly cause vascular dilatation. The zone of vasodilatation propagated equally proximal and distal to the site of irradiation within the vessel. When saline was infused into the vessel to replace flowing blood during delivery of laser irradiation, no significant vasodilatation occurred. After laser irradiation reversed surgical and pharmacologic vasoconstriction, the vessel was resistant to further pharmacologic vasoconstriction. This resistance to pharmacologic vasoconstriction did not occur if the vessel was pharmacologically predilated before delivery of laser irradiation. Pathologic analysis of the vessels revealed endothelial damage and mild to moderate medial necrosis, most significant at the site of energy delivery. These studies provide characterization of pulsed-dye laser-mediated vasodilatation in an in vivo model. Delivery of pulsed-dye laser energy has potential clinical application and warrants further investigation.

Photo-irradiation improved functional preservation of the isolated rat heart

“…Certain UV and visible lights (including laser) at low radiant doses cause vasodilation in various animal models [21][22][23]34,[42][43][44]. Photovasorelaxation was considered to be endothelialindependent relaxation of the vascular smooth muscle [21,34,44].…”

Cellular effects of low power laser therapy can be mediated by nitric oxide

“…Irradiation at different wavelengths induces vasodilatation in blood-perfused vessels but not in saline-perfused ones [5]. It was suggested that NO-hemoglobin might serve as a light-sensitive store of NO in red blood cells from which it was released by irradiation [6].…”

Laser pulse impact on rat mesenteric blood vessels in relation to laser treatment of port wine stain

“…These effects then override the light-induced dilatory effects resulting in vasoconstriction. When pulsed lasers are used, however, corresponding to much higher powers [3,15,16], vasorelaxation has been reported for a range of wavelengths (310 nm to 2.1 mm). It should also be mentioned that vasodilation with pulsed lasers was mostly investigated on arteries rather than the much smaller arterioles and venules as used in this study.…”

“…However, despite several studies which addressed the effects of laser pulses on microvasculature [2,3], only Kimel et al [4] investigated the impact of a laser pulse as used in port wine stain treatment (585 nm wavelength, 0.5 ms pulse duration). They studied threshold radiant exposures for damage to blood vessels in the chick choreo-alantoic membrane.…”