A device and method for restoring functionality of blood vessels are disclosed. Laser energy is accurately and precisely applied in order to restore vessel functionality. This is accomplished by a controlled, reliable and specific shrinkage and/or strengthening of the vessel structure by controlled transport of laser radiation via an optical fiber to the treatment site. Laser wavelength is chosen according to the required penetration depth in tissue. In a preferred embodiment, wavelength of approximately 1470 nm is used. A mini-endoscope is preferably used to control the process by visual inspection from the inside of the vessel but other means may also be combined to control the procedure. Full 360° radial emission, i.e., delivery of laser radiation perpendicularly or fairly inclined relative to the veins axis, is beneficial, and is accomplished by means of a radial emitting fiber. In another preferred embodiment, a 360 degree radiation pattern can be achieved by using a twister or side-emitting fiber, along with rotational and sweeping movements to apply energy in an even, more-controlled, and guided manner. Valve function is restored to recover whole vein functionality, avoiding the need of closing it. In a preferred embodiment, energy is applied from the outside of the vessel, by inserting a device through the skin and tissue. In another preferred embodiment, specific radiation absorbers are located at suitable positions inside the vessel wall, to selectively target radiation to tagged locations. Vessel function is restored preserving its structure. A wide range of vessel diameters are effectively treated. Vessels include veins, arteries and fistulas.
