[Thirty years of laser-assisted microvascular anastomosis (LAMA): what are the clinical perspectives?]. / Trente ans de microanastomoses vasculaires assistées par laser: des perspectives cliniques ?

INTRODUCTION: Since the first studies by Jain and Gorisch (1979), laser-assisted anastomoses have been steadily developed to a stage where clinical use is within reach. The laser-assisted vascular microanastomosis (LAMA) procedure is performed more quickly than conventional anastomosis, the surgically induced vessel damage is limited, and reduced bleeding after unclamping is observed. MATERIAL AND METHODS: A Medline literature search, for the January 1979 to February 2010 period, was performed to review articles focusing on the LAMA technique. RESULTS: The search yielded a total of 354 publications, of which 87 were relevant: 82 were animal series and five clinical studies. Microsurgical techniques and principal characteristics of LAMA in patients are the focus of the analysis. This study discusses the technological innovations and new orientations in laser welding. CONCLUSION: The first two clinical series using the 1.9-µm diode laser appear promising. Technical innovation will most likely lead to greater ease of use of the laser handpiece in the operating room.

Laser assisted skin closure (LASC) by using a 815-nm diode-laser system accelerates and improves wound healing.

BACKGROUND AND OBJECTIVE: This study aimed to evaluate a 815-nm diode-laser system to assist wound closure to accelerate and improve healing process. STUDY DESIGN/MATERIALS AND METHODS: A total of 25 male hairless rats (mutant OFA Sprague-Dawley rats, IFFA-CREDO, L'Arbresle, France) with four dorsal skin incisions were used for the study. For each wound, the good apposition of the edges was obtained with buried absorbable suture. In the laser group, the laser beam was applied spot by spot through a transparent adhesive dressing along two incisions with the following parameters: 1.5 W; 3 seconds; spot diameter, 2 mm; fluence, 145 J/cm(2). Both control wounds were closed with conventional suture techniques. The duration of the closure procedure was noted for each group. Clinical examination, histologic study, and measurement of tensile strength were performed at 3, 7, 15, and 21 days after surgery. Determination of activation of heat shock protein 70 (Hsp70) through immunocytochemistry was performed at days 1 and 7. RESULTS: LASC was 4 times faster to process than conventional suture: 1 minute 49 +/- 20.6 seconds vs. 7 minutes 26 +/- 62.2 seconds. In the laser group, healing was accelerated resulting in a more indiscernible scar than in the control groups. Histologic aspect was better with earlier continuous epidermis and dermis and a thinner resulting scar. Tensile strength was 30 to 58% greater than in control groups at 7 and 15 days (P < 0.001). Expression of Hsp70 was markedly induced in skin structures examined after laser exposure. CONCLUSIONS: This study shows the ability of the 815-nm diode-laser system to assist wound closure leading to an acceleration and an improvement of wound healing with indiscernible resulting scar. The mechanisms of this phenomenon are still unclear but further investigations are in progress to attempt to explain them.

In vivo experimental evaluation of skin remodeling by using an Er:Glass laser with contact cooling.

BACKGROUND AND OBJECTIVE: Selective dermal remodeling consists of inducing collagen tightening, neocollagen synthesis, or both, without damage to the overlying epidermis. This experimental study aimed to evaluate an Er:Glass laser emitting at 1.54 micrometer combined with contact cooling to target the upper dermis while protecting the epidermis. STUDY DESIGN/MATERIALS AND METHODS: Male hairless rats were used for the study. Different fluences (26-30 J/cm(2)) by using single 3-ms pulse irradiation or pulse train irradiation (1.1 J, 3 Hz) and different cooling temperatures (+5 degrees C, 0 degrees C, -5 degrees C) were screened with clinical examination and histologic evaluation at 1, 3, and 7 days after laser irradiation. RESULTS: The clinical effects were clearly dose and temperature cooling dependent. It seemed that single pulse irradiation led to epidermal whitening in most cases, whatever the cooling temperature. Conversely, pulse train irradiation showed reproducible epidermal preservation and confinement of the thermal damage into the dermis. New collagen synthesis was confirmed by a marked fibroblastic proliferation, detected in the lower dermis at day 3 and clearly seen in the upper dermis at day 7. CONCLUSION: This new laser seems to be a promising new tool for the treatment of skin laxity, solar elastosis, facial rhytides, and mild reduction of wrinkles.

Inhaled nitric oxide modulates leukocyte kinetics in the mesenteric venules of endotoxemic rats.

OBJECTIVE: to determine whether inhaled nitric oxide (NO) would alter leukocyte kinetics in the septic microvasculature. DESIGN: Randomized, controlled trial. SETTING: Experimental laboratory. SUBJECTS: Male Sprague Dawley rats. INTERVENTIONS: Rats were treated with either saline or endotoxin (10 mg/kg, iv) and then allowed to breathe either air or air plus NO (10 ppm). MEASUREMENTS AND MAIN RESULTS: After a 4-hr period, rolling, firm adhesion, and emigration of leukocytes and endothelial dysfunction were monitored in mesenteric venules by using intravital videomicroscopy. Compared with controls, endotoxemic rats exhibited a profound influx in mesenteric venule rolling leukocytes (55+/-17 vs. 70+/-19 leukocytes/min; p < .05), associated with a reduction of leukocyte rolling velocity (83+/-14 vs. 34+/-3 microm/sec; p < .05). In endotoxemic rats, venular endothelium leukocyte firm adhesion (1.15+/-0.32 vs. 4.08+/-0.96 leukocytes/ 100 microm; p < .05) and emigration (0.84+/-0.47 vs. 4.23+/-1.2 leukocytes/100 microm; p < .05) increased compared with controls. Inhaled NO had no effect on leukocyte kinetics in control rats. Inhaled NO significantly attenuated endotoxin-induced venular endothelium leukocyte adhesion (4.08+/-0.96 vs. 1.86+/-0.76 leukocytes/100 microm; p < .05) and emigration (4.23+/-1.2 vs. 1.68+/-0.72 leukocytes/100 microm; p < .05). Compared with control rats, macromolecular (FITC-dextran) vascular leakage, expressed as the perivenular/intravenular fluorescence intensity ratio, increased in endotoxemic rats (0.56+/-0.02 vs. 0.81+/-0.05; p < .01). Endotoxin-induced macromolecular vascular leakage increases were partially prevented by inhaled NO (0.66+/-0.01 vs. 0.56+/-0.02; p < .05). CONCLUSION: These observations suggest that inhaled NO reduces leukocyte adhesion and the degree of vascular permeability dysfunction in mesenteric venule of endotoxemic rats.

In vivo application of intestinal pH measurement using 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) fluorescence imaging.

Measurement of gastrointestinal intramucosal pH (pHim) has been recognized as an important factor in the detection of hypoxia-induced dysfunctions. However, current pH measurement techniques are limited in terms of time and spatial resolutions. A major advance in accurate pH measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). This study aimed to set up and validate a fluorescence imaging technique to measure in vivo the intramucosal pH (pHim) of the intestine. The intestine was inserted into an optical chamber placed under a microscope. Animals were injected intravenously with the pH-sensitive fluorescent dye BCECF. Fluorescence was visualized by illuminating the intestine alternately at 490 and 470 nm. The emitted fluorescence was directed to an intensified camera. The ratio of emitted fluorescence at excitation wavelengths of 490 and 470 nm was measured, corrected and converted to pHim by constructing a calibration curve. The pHim controls were performed with a pH microelectrode and were correlated with venous blood gas sampling. Results show that pHim is determined with an accuracy of +/- 0.07 pH units and a response time of 1 min. In conclusion pHim mapping of rat intestine can be obtained by fluorescence imaging using BCECF. This technology could be easily adapted for endoscopic pH measurements.

[Development and evaluation of a laser catheter with tip fiberoptic for coronary angioplasty]. / Mise au point et évaluation d'un cathéter laser avec fibre optique à boule pour angioplastie coronaire.

A fiber-optic tip catheter has been developed for treating coronary and peripheral atherosclerosis percutaneously. The catheter is coupled to an ionised Argon laser emitting at an optical power of 1 to 7 Watts. It is designed to follow a guide wire and to perform tissue ablation by a new concept combining the effects of central vaporisation and peripheral thermal remodelling of the obstructed artery. This mode of function should considerably reduce the risks of false route previously encountered with laser angioplasty. The optical and thermic properties of the catheter prototypes were determined by physical methods. These experiments showed that the temperature of the metallic component of the catheter tip did not exceed 30 degrees C at a continuous power of 6 laser Watts when the flush was functioning. It attained 400 degrees C in the absence of the flush. The performances of the catheter were then tested in a number of in vitro experiments. First of all, the catheter tip was placed perpendicularly to atheromatous cadaver aortae to study the effect of vaporisation with respect to the laser power. The threshold of vaporisation was 1 Watt (irradiance: 1100 Watts/cm2). The catheter was then introduced into plastic tubes obstructed by atheromatous plaques. This experiment demonstrated the mechanical solidity of the catheter and its flexibility in difficult operating conditions: diameter 2mm, 45 degrees angles, irregular calcified plaques. It also showed that the optimal safety-efficacy laser power was 3 laser Watts and that the exposure times varied with respect to the nature of the plaques tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of the "point-by-point technique" and the "scanning technique" for laser treatment of port-wine stain.

Photocoagulation using the argon laser has been proven to be an effective method for the treatment of port-wine stains (PWS). However, it is very difficult to reproduce the parameters of laser treatment. This leads to inaccurate energy dosages secondary to the difference in treatment patterns. The aim of this study was to compare the conventional point-by-point technique (PT) for PWS treatment against a new scanning technique (ST) using a device called "Hexascan" (PREIN & Partners, Ferney-Voltaire, France). A total of 249 patients (171 females and 78 males) using the argon laser have been studied in a retrospective study. Clinical results are presented. For each technique, blanching and hypertrophic scarring were examined. The results are classified into two groups: satisfactory and unsatisfactory. The clinical results show that the ST with the Hexascan is superior to the conventional PT. Scarring is drastically reduced because overdosage and overheating are avoided. Because of precisely controlled spot patterns, quality and homogeneity of blanching is improved. Treatment time can be reduced to 20% of that of the PT.

Robotized scanning laser handpiece for the treatment of port wine stains and other angiodysplasias.

Port wine stains are currently treated by the argon laser with the "point-by-point" technique, or the "painting technique." In both cases, the quality of the results depends greatly on the dermatologist's experience. Furthermore, the first technique is slow, and the second is painful and requires anesthesia. Therefore, we have decided to design a robotized system with the following specifications: easy, fast, non-painful treatment giving a homogeneous and reproducible blanching. The system is made of a handpiece with the scanning mechanism and a control box with the microprocessor. The system is independent of the laser (no electrical connection) and has its own power meter. The deposit of energy was optimized in function of heat diffusion in the skin. Over a 12-month period, 123 patients were treated with the robotized handpiece. The treatment modalities and the results conformed to the above-mentioned specifications. Hypertrophic scars were not reported. Therefore, we think that this system will be an interesting tool for the laser treatment of port wine stains and other cutaneous angiodysplasias.

Development of controlled Nd:YAG laser for medical applications.

Several medical fields are concerned with applications of thermal lasers such as neodymium-doped, yttrium aluminum garnet (Nd:YAG), argon, and CO2. However, quantification of the necrotic volume of Nd:YAG laser-induced damage is not possible at the time of treatment. Mathematic models and feedback control can help to optimize Nd:YAG laser treatments. We therefore formulated mathematic models for coagulation processes and developed an intelligent Nd:YAG laser system with closed-loop feedback control. Surface temperature evolution proved to be valuable data for real-time control of coagulation and ablation. Infrared thermometry provided the noncontact measurement of temperature. A computer stored the temperature data calculated by the mathematic model. Deviations of surface temperature during the treatment beyond established tolerances causes the Nd:YAG laser system to adjust the laser power automatically.