Basic techniques for laser removal of blood vessels

The basis for the treatment of any superficial diseases is the effect on the corresponding chromophores of blood vessels without damaging the surrounding skin by selecting the appropriate wavelength of the laser apparatus, pulse duration and energy density.

The main chromophore that laser radiation focuses on in the treatment of vascular formations, as a rule, is hemoglobin. As can be seen from the presented spectrum, the maximum absorption of hemoglobin falls on the green region of the laser radiation spectrum, i.e. The optimal medical laser device for removing blood vessels, at first glance, should generate a wavelength of 532 or 540 nm (KTP neodymium laser). But in fact, not for all vascular diseases, this length is optimal, because Along with the absorption of laser radiation by hemoglobin, there is a competitive absorption of laser energy by other chromophores that are contained in the skin, for example, melanin, etc.

Basic laser techniques and apparatus for laser removal of blood vessels

Currently, the following methods for laser treatment of vascular diseases are widely recognized and widely used:

1)The technique of using lasers of the “green” spectral range. The most characteristic representative of this kind of techniques and apparatus for removing blood vessels is a KTP Nd: YAG laser.

The basis of this technique is the method of selective photothermolysis. Due to the very high hemoglobin absorption coefficient inside the vessels that are exposed to laser radiation, a large amount of heat is generated, which is released in a very short time and leads to damage to the vascular walls. Due to the competitive absorption of laser radiation by melanin, the penetration depth in this case is small and is approximately 1-1.5 mm.

Thus, this technique emphasizes that “green” lasers for blood vessel removal are best used to remove superficial vascular diseases, while the use of active cooling of the skin is recommended. The use of this technique for a deeply located vascular network or for large vessels often causes side effects in the form of micro-scars. The frequency of sessions using this technique is 6-7 weeks.

2) Method of using the main wavelength of neodymium lasers.

Nd:YAG lasers generate a wavelength of 1064 nm, which penetrates the skin by 3-4 mm and is most suitable for removing large or deep vessels. With this effect on the vessel, laser energy is absorbed not only by hemoglobin, but is distributed across all target tissues that are both inside the vessel and outside. When a wavelength of 1064 is applied to a large vessel, it is not a rupture of the vessel wall that occurs, but its collapse of its wall due to coagulation properties of blood cells. Given that the rate of coagulation of proteins in the blood with increasing temperature is higher than the rate of coagulation in surrounding tissues, this technique is also quite effective and is used to treat a wide range of vascular diseases. The frequency of sessions (if re-processing of the vascular mesh is necessary) when using a wavelength of 1064 nm is usually 5-6 weeks.

Basic laser parameters for vascular removal

Despite the fact that the wavelength is very important for the treatment of vascular pathologies, the other characteristics and parameters of laser devices for removing blood vessels are no less important. The main ones are:

• The duration of the laser pulse. This parameter is closely related to the TRT (thermal relaxation time) of the vessel. When using insufficiently long pulses (in particular for neodymium laser removal of blood vessels), coagulation of blood vessels and collapse of their walls do not occur. When exceeding the permissible parameters of the pulse durations, active heat transfer occurs from the vessel to the surrounding tissue, which leads to side effects in the form of burns. When choosing a laser to remove blood vessels, the doctor must make sure that the hardware techniques allow you to change the duration in a wide range for the effective removal of various types of vessels (from 5 to 30ms).
• Laser fluence. This parameter is one of the key not only for laser removal of blood vessels, but also for most non-ablative laser procedures. For the treatment of vascular diseases, energy densities from 5 to 20 J / cm2 for green spectral lasers and energy densities from 100 to 350 J / cm2 for a length of 1064 nm are used. For smaller vessels (with a diameter of 1-2 mm) lower values of the energy density are used and, accordingly, for larger vessels, higher values of the energy density are used for full coagulation.
• Laser beam distribution profile. For laser removal of blood vessels, profiles with a Gaussian or flat spatial distribution of energy (Flat Spot) are used. For thinner and single vessels, the Gaussian distribution is more effective, because allows you to focus energy inside the vessel. In the treatment of superficial vascular diseases of a large area, the Flat Spot distribution is more efficiently used because even distribution of energy over the area minimizes the risk of micro-scar formation.

It is the consideration of all these factors and parameters that is necessary for the effective removal of a wide variety of superficial vascular formations.