How Endovenous Laser Ablation (EVLA) works
Endovenous Laser Ablation (EVLA or EVLT) works by ablating the vein which is to be treated by heating it up from inside using energy from a laser. The process of heating the vein until it is dead is called “thermoablation”.
The laser energy is introduced into the vein to be treated by using a hollow needle called a “cannula” which is inserted into the target vein under ultrasound guidance. Once the hollow needle is positioned correctly in the correct vein, a laser device can be passed up into the vein and then positioned using ultrasound.
The simplest form of Endovenous Laser Ablation (EVLA or EVLT) is a bare optical fibre (or laser fibre) that is passed up the inside of the vein. This method is now very rarely used. The usual current methods are either to pass a wire up inside the vein followed by a sheath which guides the bare optical fibre into position and protects it, or devices where the optical fibre for the laser is within a sheath already and the whole device is passed up the vein at the same time.
Most of the different fibres and devices direct the laser energy to fire forwards out of the end of the fibre or device. Some fibres now have sheaths around their treatment tips, made of different materials, in order to try to “stabilise” the end allowing the laser energy to be directed straight forwards or outwards like a cone and not into the wall at one point to risk perforation.
Recently, one device has been produced which is a great advance over the forward firing endovenous laser design. The “radial firing” laser is a device where the optical laser fibre is contained within a sheath, but at the treatment tip, the laser energy is diverted outwards at 90° to the fibre. This means that all of the laser energy is directed straight into the vein wall where it is needed and not fired down the lumen of the vein as in the forward firing endovenous laser devices. This allows a far greater accuracy of treatment, less chance that the laser energy will concentrate in one area and perforate the wall of the vein and a greater predictability of outcome from the treatment. It also makes it more versatile as to which veins can be treated.
Different companies use different wavelengths of laser for Endovenous Laser Ablation (EVLA or EVLT). Although there are many claims made as to the advantages of one sort of wavelength or the other, there is little definitive evidence to show that any particular wavelength has advantages over the others, provided the correct treatment protocols are used.
This is quite a complex area of study and for more information please see the book “Understanding Endovenous Treatments – Principles for successful endovenous laser, radiofrequency ablation, foam sclerotherapy and other endovenous treatments” produced by The College of Phlebology.