1.9 µm diode laser assisted vascular microanastomoses: Experience in 40 clinical procedures.

BACKGROUND: Since the initial work of Jacobson and Suarez in 1960, microsurgery has evolved greatly. In 2009, we reported our clinical experience with 1.9 µm diode laser-assisted vascular microanastomoses (LAMA) for free flap reconstruction. In this report, the ongoing study is now expanded to include 11 additional procedures which were analyzed prospectively with a focus on the duration of the LAMA technique. METHODS: In total, 40 clinical procedures with LAMA have been performed since 2005. Mean follow-up was 3.3 years (range 0.5-5.5 years). Among those, 11 procedures were performed and prospectively analyzed during the period 2008-2009. LAMA was performed with a 1.9 µm diode laser after placement of equidistant stitches. For vessels size <1.5 mm, the following laser parameters were used: spot size 400 µm, five spots for each wall, power 125 mW, arterial/venous fluence 100/90 J/cm(2) (spot duration 1/0.9 seconds). RESULTS: For the last observed 11 procedures, mean occlusion time of the flap arterial and venous anastomoses was 5.4 ± 0.4 and 6.8 ± 0.7 minutes respectively. One anastomosis required a secondary laser application. Arterial and venous patency rates were 100% at the time of surgery. The success rate for the 11 procedures was 100%. The global success rate of the series (97.5%) is discussed and compared with the literature. CONCLUSION: The success rates for reconstructive free flap surgery realized with LAMA appear excellent. Technical innovation will most likely lead to widespread use of the handpiece laser in the operating room.

[Blood flow assessment with magnetic resonance imaging after 1.9 µm diode laser assisted arterial micronastomoses]. / Évaluation du flux sanguin par imagerie en résonance magnétique fonctionnelle après anastomoses artérielles assistées par laser diode 1,9µm.

INTRODUCTION: The most important factor for successful free-flap transfer and replantations is a well-executed anastomosis. The aim of this study is to assess blood flow after laser assisted arterial microanastomosis (LAMA) using a 1.9 µm diode laser. MATERIALS AND METHODS: LAMA was performed on a series of 10 carotidis on Wistar rats. Two 10/0 stay sutures and a standard laser tissue welding technique (λ: 1.9 µm; power: 120mW) were used. Similarly, a series of 10 conventional arterial anastomosis were performed (CSMA). For the two groups, contralateral non-operated carotidis were used as control. A positioning sequence, an anatomical sequence, an angiographic sequence and a flow sequence were performed 1 day after operation and then after 1, 4 and 8 weeks. RESULTS: The arterial patency rate was 100% at the time of surgery. The mean clamping time was 7.2 min in the LAMA group compared to 10.7 min in the CSMA group. In the angiographic sequence, there were no aneurysms in both groups for all observation periods. At postoperative day 1, the mean loss of blood flow at the level of anastomosis in the LAMA group was 6% compared with 14% in the CSMA group. After 1, 4 and 8 weeks, there was an unhooking of the blood flow in the CSMA group: the loss of blood flow was 23%, 27% and 31% respectively, compared with 10%, 12% and 13% in the LAMA group. Moreover, one case of thrombosis was observed in the CSMA group after 1 week. CONCLUSION: The flow-MRI emphasizes that 1.9 µm diode laser assisted microvascular anastomosis appears to be a consistent and reliable technique. These results show that 1.9 µm diode laser assisted microvascular anastomosis has potential for further development in the near future.

Laser assisted septal cartilage reshaping (LASCR): A prospective study in 12 patients.

BACKGROUND AND OBJECTIVES: Occurring in one-third of the population, nasal obstruction is the most common complaint in an average rhinologic practice. The etiology is usually a deviation of the nasal septum, although other conditions, such as turbinate hypertrophy, can also cause nasal obstruction. Our team has already demonstrated that laser assisted cartilage reshaping can be used effectively for the correction of ear protrusion. This study aims to evaluate laser assisted septal cartilage reshaping (LASCR) to treat septal deviation. STUDY DESIGN: Between March 2009 and September 2009, 12 patients (8 males, 4 females-mean age: 23 years) underwent LASCR for treatment of septal deviation. The mean NOSE score was 11.6. Preoperative examination included rhinomanometry and nasal endoscopy to exclude inferior turbinate or adenoid hypertrophy. Both sides of the septum were irradiated using a 1,540 nm laser connected to a 4 mm spot handpiece with integrated cooling (fluence: 50 J/cm(2)). Contact cooling made the treatment tolerable, but topical anesthesia was still required. Immediately after the procedure, an internal splint was inserted into the nostril and kept for 7 days. The NOSE score was calculated at 1 week, 1 month, and 3 months post-procedure and a rhinomanometry was carried out at 3 months. RESULTS: The entire procedure took an average of 20 minutes. For all procedures, there were no lesions of the septal mucosa. Three months post-op, mean NOSE score improved from 11.6 to 5.3. Rhinomanometry assesses an increase in airflow (+19%) and improvement to air inflow resistance (-16%), confirming a subjective improvement. In seven adults, the expected septal reshaping was achieved. In five adults, incomplete septum reshaping was observed. In three patients it was correlated to anatomical variations: a thick septum in two cases and a long septum in one case. In the remaining two patients, it was due to insufficient fluence. In these cases, insufficient local anesthesia did not allow us to finish the procedure and the patients received a fluence of 30 J/cm(2) only. Those patients were re-treated at 3 months at 50 J/cm(2) fluence and all achieved suitable reshaping. CONCLUSION: LASCR is a safe and less morbid approach to surgical septoplasty. Since significant variability in the cartilaginous elements of the nose is the rule rather than the exception, some improvements in the technique are still required.

Blood flow assessment with magnetic resonance imaging after 1.9 microm diode laser-assisted microvascular anastomosis.

BACKGROUND AND OBJECTIVES: Microvascular surgery associates intricate surgical techniques to join tiny blood vessels and help transfer large amount of tissues. Successful venous anastomosis remains the main challenge because inadequate blood flow correlates with a major risk of free flaps venous congestion and thrombosis. The aim of this study is to assess blood flow after laser-assisted microvascular anastomosis (LAMA) using a 1.9-microm diode laser. STUDY DESIGN/MATERIALS AND METHODS: LAMA was performed on a series of 10 external jugular veins of Wistar rats. Two stay sutures and a standard laser tissue welding technique (lambda: 1.9 microm; power: 110 mW) were used. Similarly, a series of 10 conventional venous anastomosis were performed (CSMA). In both groups, contralateral non-operated jugular veins were used as control. MRI was used to perform positioning, anatomical, angiographic blood flow sequences, 1 day post-procedure and at 1, 4 and 8 weeks. RESULTS: Venous patency rate was 100% at the time of surgery. Mean clamping time was 7.9 minutes in the LAMA group compared to 11.4 minutes in the CSMA group. In the angiographic sequence, there were no aneurysms in both groups for all observation periods. At post-operative day 1, mean loss of blood flow at the level of anastomosis in the LAMA group was 7% compared with 22% in the CSMA group. At 1, 4 and 8 weeks, blood flow reduction was greater in the CSMA group: 34%, 38% and 41%, respectively, compared to 12%, 15% and 16% in the LAMA group. Moreover, three cases of thrombosis were observed in the venous anastomosis performed with the conventional technique at 1 (n = 2) and 3 months (n = 1). CONCLUSION: The flow-MRI further demonstrates that 1.9 microm diode LAMA is a consistent, reliable and reproducible technique, capable of improving blood flow in veins when compared to conventional surgery.

Evaluation of BCECF fluorescence ratio imaging to properly measure gastric intramucosal pH variations in vivo.

Our purpose is to evaluate intramucosal gastric pH video imaging by 2('),7(')-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) fluorescence ratio techniques. We use a video endoscopic imaging system and BCECF as the pH fluorescent probe. Systemic in vivo pH variations are studied in 10 pigs: five in the control group and five with respiratory acidosis induced through rebreathing. The intramucosal pH of the gastric wall is measured every 5 s and the results demonstrate a good correlation (pearson correlation=0.832) between blood gases pH measurements and pH measured with the video endocopic imaging system. Our results confirm the feasibility of using BCECF fluorescence pH imaging to measure intramucosal pH in vivo.

Outcomes after 1.9-microm diode laser-assisted anastomosis in reconstructive microsurgery: results in 27 patients.

BACKGROUND: Microvascular surgery has become an important method for reconstructing surgical defects resulting from trauma, tumors, or burns. The most important factor for successful free flap transfer is a well-executed anastomosis. This study was performed to review the authors' experience with a 1.9-microm diode laser in microsurgery, with special attention to outcomes and performance of the technique. METHODS: Between January of 2005 and December of 2007, 27 patients underwent microsurgery with a 1.9-microm diode laser at the authors' institute. The patients had a mean age of 31 years (range, 2 to 59 years); 14 patients were women and 13 patients were men. This technique was used for digital replantations (n = 2) and for free flap transfer (n = 27). Causes of the defects were trauma (n = 14), tumor (n = 9), congenital (n = 2), burn (n = 1), infection (n = 1), arthritis (n = 1), and dog bite (n = 1). Laser-assisted microvascular anastomosis was performed with a 1.9-microm diode laser after placement of equidistant stitches. The following parameters were used: spot size, 400 microm; power, 125 mW; time depending on vessel size (0.8 to 1.8 mm); and fluence varying from 70 to 200 J/cm. RESULTS: Three surgical revisions following hematoma and one rupture of the arterial anastomosis leading to a free deep inferior epigastric perforator flap necrosis resulting from high-dose radiotherapy before surgery occurred after laser-assisted microvascular anastomosis, accounting for an overall success rate of 96.6 percent. CONCLUSION: This study reports the numerous benefits of the technique: easier performance of vascular anastomosis with difficult access, decrease of reperfusion bleeding and complications, and a short learning curve.

Laser preconditioning of calvarial bone prior to an X-ray radiation injury: a preliminary in vivo study of the vascular response.

BACKGROUND AND OBJECTIVES: Thermal preconditioning prior to injury induces a cytoprotective effect on soft tissues and promotes their recovery. Lasers are an adequate tool to generate controlled and reproducible heat. X-ray irradiation induces a chronic antiangiogenic effect on bone, affecting its healing and remodeling processes. The aim of this study was to investigate the effect of laser preconditioning on the re-vascularization of X-ray irradiated bone. MATERIALS AND METHODS: A bone chamber was implanted onto the calvaria of rabbits to study the vascularization process. Digital pictures were taken of the vascular plexus at the target bone site using a modified digital camera. Vascular density (VD) was determined using image processing. It was defined as the ratio of blood vessel pixels to the total number of pixels to the region of interest. Laser preconditioning was performed with a diode laser (810 nm, 2 W, 3 seconds, 48 J/cm(2), 4 mm). A 12-week follow-up study was performed on 20 rabbits divided into four groups: #1: control group (n = 5); #2: laser irradiation alone (n = 5). #3: X-ray radiation (18.75 Gy) alone (n = 5), #4: laser preconditioning 24 hours prior to X-ray radiation (n = 5). RESULTS: VD remained stable during the 12-week follow up for group #1. No significant difference was observed between laser irradiation group (#2) and control group (#1) (P>0.5). The angiolytic action of X-ray radiation was confirmed in groups #3 and #4, which were statistically different from group #1 (P<0.001). However, the decrease of the vascularization was limited in group #4 highlighting a different evolution between group #3 and #4 (P<0.05). These results were confirmed by histological analysis. DISCUSSION AND CONCLUSION: The bone chamber is an effective reproducible method for the longitudinal analysis of the dynamics of vascularization. Our findings have shown that laser preconditioning is capable of preserving vascularization in an X-ray irradiated bone site, thus suggesting a novel approach for promoting the healing of bone tissue in which the vascular supply has been damaged.

Effect of a laser irradiation on the vascularisation of safety and X-ray radiated bone.

Thermal preconditioning induces a cytoprotective effect and promotes tissue recovering. Laser is an appropriated method to generate a controlled and reproducible heating. Bone healing, a crucial challenge in medicine, is affected by X-ray radiation which induces a chronic antiangiogenic effect. So, this study aims to investigate the role of laser preconditioning on the vascularisation of bone after X-ray radiation. An optical bone chamber allowed the study of the vascularization process. The vascular density (VD) was determined using image processing. A longitudinal study was performed on 20 rabbits divided in four groups: #1: control group (n=5); #2: laser irradiation alone (diode laser 810nm, fluence= 48J/cm2) (n=5). #3: X-ray radiation (18.75Gy) alone (n=5), #4: laser preconditioning 24 hours before a X-ray radiation (n=5). VD remained stable during 12-week follow up for groups #1 and #2. X-ray radiation lead to an important decrease of the superficial bone vascularization in group #3. The decrease of the vascularization was limited in group #4 highlighting a different evolution between group #3 and #4. Those results were confirmed by histological analysis. Our preliminary findings show that laser preconditioning preserves vascularization in X-ray radiated bone site, outlining a novel approach for the bone healing in which the vascular supply has been injured.

Study of platelet behavior in vivo after endothelial stimulation with laser irradiation using fluorescence intravital videomicroscopy and PEGylated liposome staining.

Platelets contain an array of potent proinflammatory mediators, and therefore they are regarded as mediator and effector cells in inflammation. Knowing the role of platelets during these processes is crucial and the analysis of their behavior in situ and the associated mechanisms is consequently particularly important. However, conventional in vitro staining techniques induce modification of the characteristics of platelets. This study aimed to evaluate platelet behavior in vivo after endothelial stimulation (without endothelial denudation or exposure of basal lamina and/or collagen) with an argon laser, using video intravital microscopy in combination with a new an innovative platelet staining technique based on polyethyleneglycol (PEG) liposomes. The study was performed on skin by using a dorsal skin-fold chamber implanted in golden hamsters. Platelets were stained by 5,6-CF-encapsulated PEGylated liposomes injected intravenously. The skin microcirculation was observed with an intravital microscope (using x25, x40, and x80 magnifications) fitted with a xenon light source, an epifluorescence assembly, and an ultra-high sensitivity video camera for fluorescence imaging. Platelet activation without endothelial denudation or exposure of basal lamina and/or collagen was obtained with an argon laser emitting at 514.5 nm with the following parameters: 20 mW, 300 ms, 120 J/cm(2). The 80-microm laser beam was focused on a vessel and its position was controlled with the microscope. Thanks to the spatial resolution of the intravital microscopic imaging system, the platelets were seen rolling individually on the endothelium. After laser stimulation, platelets were activated and three phases were observed: recruitment, adhesion and detachment. The observation of these three phases was time dependent and the kinetics of the process were quantified. The recruitment reached a maximum after 90 +/- 20 s. The adhesion phase lasted for 110 +/- 25 s. At last, detachment of all platelets was observed. This detachment started 200 +/- 20 s after irradiation and was completed in less than 2 min. This study confirms that laser irradiation used with optimal parameters can induce platelet activation without thrombus formation. Platelets can adhere only transiently on stimulated endothelium. This phenomenon may therefore represent a defense mechanism, by which platelets would accumulate in the vicinity of an injury, making them available for immediate response. At last, this study has clearly demonstrated the advantages of our new and innovative platelet staining method using PEGylated liposomes, which are (i) in situ labeling, (ii) use of a hydrophilic marker located in an aqueous compartment within the platelet, and (iii) labeling of platelets allowing observation during the whole experiment.