Experimental comparative study on morphological effects of different lasers on the liver

Abstract

Three types of laser radiation were compared as to their capabilities in hepatic surgery using 17 New Zealand rabbits. In four animals, subtotal scalpel lobectomy was performed, the hepatic pedicle being clamped. Hemostasis is obtained by means of argon or Nd YAG laser as long as the internal diameter of the vessels encountered is less than 4.5 mm. Nd YAG laser requires a power output four times higher than argon laser to obtain hemostasis. In six animals limited resection was performed by means of Nd YAG and CO2 lasers. CO2 radiation supplied insufficient hemostasis whenever the vessel diameter was more than 1 mm despite an excellent cutting power. Nd YAG radiation created an important necrosis zone due to thermal diffusion. In seven animals various focal hepatic lesions produced by the three types of laser were compared. Argon laser induced superficial and regularly round lesion, Nd YAG laser deeper, cauliflower-like lesions with thermal diffusion following especially vessels. Veins presented thrombosis of their blood content and coagulation necrosis of their wall. The amount of glycogenic granulation decreased. The CO2 laser induced very sharp punctual lesion without necrosis. Electron-microscopic sections revealed faint shadowy liver cells closet to the thermal source and bubbled mitochondria containing disrupted critea around the lesion. In later lesions Nd YAG laser produced more extensive fibrosis than argon or CO2 laser. After first clinical trials we believe that laser irradiation is actually an adjuvant safety factor in current hepatic surgery, whereas the Nd YAG laser could be of real interest in metastatic carcinoma destruction in liver.

Comparative study of conventional scalpel and CO2-laser in experimental tumor surgery

“…Advantages of the laser method, such as tumor cell vaporization [15] and less hemorrhaging at the site of cutting [2,7,12,19], were reported. The question about lymph vessel occlusion ("sealing") by the laser remains controversial: H3-1abeled thymidin was reduced in regional lymph nodes when the laser was applied [14].…”

Hepatic Resection With an Nd.YAG Laser in Pig

“…A focused beam induces a very small impact on the surface of the tissue to be incised, which means a punctual energy density and important diffusion beyond this point will warm hepatic parenchyma before cutting it [4,5], and induce a large section sulcus and important parenchymatic damage [5,10,12]. We found out that the lower the beam divergence the thinner the cellular destruction was.…”

“…The immediate hemostatic benefits of the Nd:YAG were controlled bleeding from veins of up to 4.5 pm in diameter [4,5] and the control of parenchymatic oozing from the cutting edges with minimized blood loss. This permitted rapid resection, although major vessels sometimes required ligation.…”

Thermo-controlled device for inducing deep coagulation in the liver with the Nd:YAG laser

“…In the past the Neodymium-doped Yttrium Aluminium Garnet (Nd:YAG, 1064 nm) laser mainly served as a light source, because of its deep light penetration in biological tissue [10,11]. The light application system is equally important to reach an effective coagulation zone within a few minutes.…”