Determination of efficient parameters for argon laser‐assisted anastomoses in rats: Macroscopic, thermal, and histological evaluation

Abstract

The aim of this study was to determine efficient parameters for an argon laser (spot diameter = 200 microns) to obtain and reproduce vessel anastomoses. It was performed in two groups of Wistar rats. In the first group (89 Laser impacts on 10 carotids), the fluence was continuously adjusted from 30 to 3,000 J/cm2 in order to determine efficient sets of parameters (power from 90-200 mW, pulse duration from 0.1 to 5 seconds, pulsed or continuous mode). In the second group, 30 end-to-end carotid anastomoses were performed. The results were evaluated by macroscopic thermal, and histological studies. The second group proved the efficiency of the selected parameters. Vessel welding was obtained with 100 mW, 3 seconds, continuous mode (fluence = 950 J/cm2, irradiance = 320 W/cm2) for a mean temperature of 77 degrees C corresponding to collagen denaturation. In the second group the patency rate was 93% (28/30) with three pseudo-aneurisms and two thromboses. Histological studies noted slight modifications of the media.

Quantitative changes in collagen levels following 830-nm diode laser welding

“…White, Kopchok, and others [2][3][4] confirmed this fact with argon laser welding of vessels, but they proposed that collagen was not denatured after argon laser irradiation. However, other investigators [5,6] using the same laser type demonstrated that collagen denaturation had occurred. Brooks et al [7], using a histological technique with picrosirius red F3BA staining, confirmed that vascular tissue was denatured in argon laser welding.…”

Pathophysiological mechanisms of high-intensity focused ultrasound-mediated vascular occlusion and relevance to non-invasive fetal surgery

“…A similar tissue vaporization is seen in HIFU tissue emulsification, although tissue carbonization is less likely to occur as desiccated tissue cannot propagate ultrasound, and further heating does not occur beyond this point. Successful vascular occlusion by collagen fusion occurs in temperature range 73-878C [57], while temperatures below 548C caused no structural changes in collagen [57].…”

Laser-assisted vessel welding: state of the art and future outlook

“…For example, the infrared CO2 laser wavelength (λ = 10,600 nm) is predominantly absorbed by water, resulting in a superficial OPD, whereas the visible and near-infrared wavelengths of diode lasers (λ = 670-988 nm) exhibit a significantly greater OPD in tissue. The absorption of some lasers can be selectively enhanced by pigment molecules (i.e., hemoglobin and melanin) [20,21,30,36,72,77] or exogenous dyes, such as indocyanine green (ICG) [78] and fluorescein isothiocyanate [53]. The degree of heat build-up is determined by the laser irradiance (W/cm 2 , i.e., power output (W) / spot area (cm 2 )), radiant exposure (J/cm 2 , irradiance × irradiation time (s)), and the lasing mode (i.e., continuous or pulsed mode).…”

“…Unfortunately, several drawbacks associated with current (native) LAVW techniques [6,18,20,26,34,44,45] have hampered its transition from the experimental to the clinical setting [40,44,45]. First, the relatively low welding strengths produced with LAVW often require additional sutures to reinforce the anastomosis, ultimately defeating the purpose of the modality.…”

“…First, the relatively low welding strengths produced with LAVW often require additional sutures to reinforce the anastomosis, ultimately defeating the purpose of the modality. [3,[5][6][7][8]10,[12][13][14]18,20,22,24,26,28,30,32,[34][35][36]40,67,69,70] Second, extensive thermal damage may extend to the basal membrane of the intima ( Figure 1) and cause intimal hyperplasia [7,20], thrombosis [7,26], and aneurysm formation [13,15,21,34,38,71,72]. To overcome these disadvantages, several more refined welding techniques have been developed, including sLAVW, scaffold-and solder-enhanced LAVW (ssLAVW) (Figure 2), and photochemical laser-assisted tissue bonding.…”