Laser-assisted microsurgical anastomosis

A low power carbon dioxide laser was used to perform 212 end-to-end laser-assisted microvascular anastomoses (LAMA) of femoral arteries (mean diameter, 1.2 mm) in Sprague-Dawley rats. Eighty-two conventional microvascular suture anastomoses (CMSA) utilizing 10-0 monofilament interrupted sutures were done for comparison of techniques and wound healing. The mean duration of each anastomosis procedure was 16 minutes for the LAMA repairs, compared to an average of 27 minutes for the CMSA repairs (P less than 0.05). All anastomoses were patent at the completion of the procedure. Each laser-assisted anastomosis required an average of seven intermittent laser exposures of 0.1 to 0.3 seconds each with approximately 80 mW of CO2 (wavelength = 10.6 micron) radiation at a spot size of 150 micron. A patency rate of 95% was obtained on the LAMA vessels (202 of 212) compared to 96% for the CMSA repairs (79 of 82). A total of 14 aneurysms were noted in the LAMA group (7%) compared to 11 in the CMSA (13%). All aneurysms were in patent vessels. Histological analysis indicates that the progression of wound healing of LAMA and CMSA anastomoses follows similar paths chronologically and morphologically with increased scar tissue formation around the suture. Scanning electron microscopy confirms the comparable luminal healing of the LAMA and CMSA vessels, with complete reendothelialization occurring by 3 weeks postoperatively. The tensile strength of the LAMA repair, although low immediately after operation, is comparable to that of the intact artery at 21 days. These findings suggest that a low energy carbon dioxide microsurgical laser has potential beneficial clinical application for anastomosis of small vessels.     

Diode laser and microvascular carotid anastomosis: A preliminary study

A crossed carotid end-to-end anastomosis was performed in 20 Wistar rats by means of a diode laser device (wavelength 830 nm and power output 3 W in continuous wave). The diode laser energy was delivered into a micromanipulator coupled to an OPMI 1 Zeiss operating microscope with a focused spot of 300 μm diameter. The vessel sealing was effected on common carotids (0.8–1.2 mm) using laser shots (average 9) of 680 mW power and 4.5 s duration and 962 W cm⁻² irradiance each. The good vascular flow was confirmed by Doppler spectral analysis and angiography performed on days 0, 10 and 30. Light and scanning electron microscopy showed that reendothelialization was complete on day 10 whilst collagenous fusion of media and adventitia was obvious. The patency rate was 90% impaired by a lethal thrombosis. The efficiency of the diode laser was compared to that of other types of LAVA and to manual microanastomosis.     

Laser-assisted venous anastomosis: a comparison study

A low-powered carbon dioxide laser was used to perform 25 vein grafts (50 anastomoses) on the femoral veins of Sprague-Dawley rats. The patency rate, clamp time, and bleeding time were compared with 50 conventional microvascular vein grafts (100 anastomoses). The patency of the laser-assisted anastomoses (LAVA) was 84 percent, while the conventional vein grafts yielded a 94 percent patency rate. The average clamp time and bleeding time for the LAVA were 47.2 min and 4.88 sec, respectively, while the conventional anastomoses required 57.6 min and had an average bleeding time of 9.44 sec. Histologically, both specimens healed at the same rate, but the laser-assisted anastomoses produced less inflammation and granulation tissue. These results suggest that the laser has potential as a tool for clinical application in microsurgery. In addition, the 94 percent patency rate achieved with the vein interposition graft would suggest that a decrease in the tension across the anastomosis can improve patency.     

Microvascular anastomosis using carbon dioxide (CO2) laser: evaluation by SEM after corrosion cast

In order to compare the carbon dioxide laser-assisted microvascular anastomosis (CO2 LAMA) with conventional microvascular sutured anastomosis (CMSA), 40 microarterial anastomoses were performed in Wistar albino rats. At different time intervals from zero to four weeks after the procedure, the anastomoses were examined under the scanning electron microscope (SEM) after resin corrosion cast (Mercox). CO2 LAMA was easier and less time-consuming than CMSA, with the same patency rate. Healing of the lumen surface was similar in both procedures, suggesting that CO2 LAMA can be reliably used in microvascular anastomosis.     

Microarterial anastomosis using a noncontact diode laser versus a control study

A series of direct carotid end-to-end laser anastomosis vs. direct manual suture was carried out on a series of 70 Wistar rats (mean weight 260 g). Both common carotids (0.8–1.2 mm) were sectioned and repaired. The left side (n = 70) was submitted to laser-assisted microvascular anastomosis (LAMA) performed by means of a diode laser device (wavelength 830 nm and power output 3 W in continuous wave) without chromophore. The right side (n = 70) underwent a control manual suture (CMA). The diode laser energy was delivered into a micromanipulator coupled to a Zeiss operating microscope with a focused spot of 300 μm in diameter. After placement of three 10.0 stitches for edge coaptation, the LAMA was achieved using laser shots (average 3) of 500 mW power, 4.5 s duration, and 700 W/cm² irradiance each. The CMA was performed by means of six 10.0 stitches. The good vascular flow was confirmed by Doppler spectral analysis (n = 466) carried out from day 0 to day 90. Light and scanning electron microscopy (n = 82) showed that re-endothelialization after LAMA was gaining ground on day 3, whereas collagenous network developed in the media scar by day 10. In contrast, after CMA the arterial repair was delayed on day 20, inducing a media fibrotic scar. The patency rate was 93% in both anastomoses. The shorter operating time (13 min for LAMA vs. 22 min for CMA) and the noncontact laser technique are the main intraoperative advantages. The technical benefits of the diode laser are pointed out. © 1994 Wiley-Liss, Inc.     

Surgical application of low-power laser: experimental study, development of equipments and clinical application

We carried out experimental and clinical studies with low-power laser to perform the surgical application. The developed device for microvascular anastomosis with semiconductor laser diode made of In-Ga-As-P was used to perform 15 end-to-end laser assisted microvascular anastomoses of carotid arteries in rabbits. In four of 7 cases which were irradiated with power output 50mW showed patency immediately after surgery with no wound disruption. A new medical device with Ga-A1-As semiconductor laser diode was developed for pain relief. A double-blind evaluation of the test was initiated in 124 patients suffering from chronic inflammatory pain. Result is that of 63 patients irradiated laser, 45(71%) were effective and of 61 cases not irradiated laser, 8(13%) were relieved pain. The data were analyzed statistically by chi square, and criterion for statistical significance was the 0.01 level. The spectral properties of laser-excited fluorescence of three photosensitizers, namely tetracycline, hematoporphyrin free base and chlorin e6Na, taken up in human arterial intima were detected. Photosensitizers were administrated to resected human arteries for 2 hours in vitro. The main results are following: 1) Photosensitizers are confirmed to be taken up in arterial intima and the fluorescence intensity decreases as the time goes on. 2) The fluorescence intensity from atheromatous plaque is usually stronger than that from normal region.     

Laser-assisted vasal anastomosis in the rat and man

In order to study the efficacy of laser-assisted vasal anastomosis (LAVA), a microscopic carbon dioxide surgical laser (Xanar) was utilized in the anastomoses of human vas deferens in vitro and the Sprague-Dawley rat vas deferens in vivo. The longitudinal tensile and internal hydrostatic pressure strengths of laser-assisted vasal anastomoses were compared to conventional microsurgical suture anastomoses in the human vas deferens. The LAVA group had a greater mean internal hydrostatic pressure strength (p less than 0.001) and a lesser mean longitudinal tensile strength (p less than 0.001) than the conventional microsurgical group. Further evaluation was performed in the Sprague-Dawley rat model, comparing post-operative fertility, patency, healing and sperm granuloma occurrence among four surgically treated groups and a control group: LAVA, conventional suture anastomosis, sham operated, and vasectomized. Light and scanning electron microscopic examination revealed equivalent healing in both the LAVA and conventional groups. Fertility was not statistically different in the LAVA, conventional, control, and sham operated groups. However, the incidence of gross sperm granulomas observed in the LAVA group (80%) was much higher than in the conventional suture anastomosis group (0%). In conclusion, laser-assisted vasal anastomosis is a fast and simple technique for vasal reanastomosis and was as successful (in pregnancies) as conventional suture anastomosis in producing fertility in rats undergoing vasal reanastomosis, but the incidence of sperm granuloma is higher.     

Experimental laser-assisted end-to-side microvascular anastomosis

The authors present a new technique of end-to-side microvascular anastomosis in a rat carotid artery model, employing a milliwatt CO2 laser. Both carotid arteries were isolated and approximated in an end-to-side fashion by the placement of four 10-0 nylon stay sutures. The milliwatt CO2 laser was used to effect vessel anastomosis between the sutures, using 70-100 mW of power. Animals were killed 8 weeks postoperatively. Angiography of each anastomosis was performed in all animals. All anastomoses were then harvested, and submitted for histological analysis. Anastomotic patency was 100%, both intraoperatively and angiographically. There was no evidence of intravascular thrombus, anastomotic stenosis, or pseudoaneurysm formation. Early in the experiment, some anastomoses showed localized dilatation at the anastomotic site. The histologic changes at the anastomotic site are described. Laser-assisted microvascular anastomosis is a feasible technique, and a potential alternative to conventional suture techniques.     

Laser-assisted vascular end to end anastomosis of elastin heterograft to carotid artery with an albumin stent: a preliminary in vivo study

BACKGROUND AND OBJECTIVES: Laser-assisted end to end vascular anastomosis of an elastin heterograft to native artery may prevent problems associated with currently available vascular synthetic grafts and conventional suture anastomosis. STUDY DESIGN/MATERIALS AND METHODS: A total of 21 anastomoses in the carotid arteries of 7 domestic swine were performed with an 800 nm laser and an albumin stent plus solder. There were 5 artery to artery and 16 elastin heterograft to native artery anastomoses. Operative parameters, vascular patency, and histology of the anastomoses were evaluated. RESULTS: Out of 21 anastomoses, 16 were patent for 3 hours. One artery to artery anastomosis was thrombosed and four elastin heterograft to artery anastomoses were excluded from the study due to heterograft burst. The average amount of applied energy was 212 J for artery to artery anastomosis and 273 J for elastin heterograft to native artery. Histology shows coagulative necrosis of the adventitia, hypereosinophilic contraction band in the media of native arteries and no changes in elastin heterografts. CONCLUSIONS: Laser-assisted vascular anastomosis (LAVA) of elastin heterograft to medium size vessel using an albumin stent is feasible. Chronic studies are warranted to determine long-term patency and histology of the LAVA.     

CO2 and Nd:YAG laser systems in microsurgical venous anastomoses

Summary A comparative study was undertaken in 81 rats to investigate a CO₂ and Nd:YAG laser system for laserwelded anastomosis of the femoral vein. Conventionally sutured anastomoses (CMSA) served as controls. Laserwelded anastomosis (LAMA) was easier and could be performed 30% faster than CMSA. Postoperative investigations included patency tests, postmortem examinations and light and electron microscopy. Aneurysms were not seen. Foreign-body reaction was more pronounced in CMSA. Patency rates for CO₂-LAMA and CMSA were equal, whereas Nd:YAG-LAMA resulted in significantly higher rate of early postoperative thrombosis (P<0.01). Because of its physical properties, the CO₂-laser system seems to be better suited for laser welding of delicate structures such as the rat femoral vein.     

Endoluminal laser-assisted vascular anastomosis—an in vivo study in a pig model

Microvascular surgery is time consuming and requires high expertise. Laser-assisted vascular anastomosis (LAVA) is a promising sutureless technique that has the potential to facilitate this procedure. In this study, we evaluate the handling of our soldering material and the 1-week patency rate in a porcine model. Six pigs were subjected to LAVA. For each pig, the saphenous artery on one side was transected while the contralateral side was used as control. A porous polycaprolactone scaffold soaked in 40% (w/w) bovine serum albumin solution in combination with 0.1% (w/w) indocyanine green was wrapped at the anastomosis site and at the control site. Both sides were then soldered with a diode laser coupled into a light diffuser fiber emitting radiation with a wavelength of 808 nm and a power of 2–2.2 W. Vessels were successfully soldered with a 100% immediate patency rate. The 1-week patency rate was 83% for the anastomoses versus 67% for the control side. Vessels irradiated for 80 to 90 s tended to maintain the highest patency rate. Macroscopically, there was no difference between the two sides. The patch was easy to handle provided that the environment could be kept dry. This study shows the potential and the limitations of endoluminal LAVA as a one-step procedure without the use of stay sutures. Further studies are needed to improve the soldering material, the long-term patency rate, and standardized irradiation parameters. The long-term effects of laser soldering on the vessel wall remain to be determined.     

Patency of laser-assisted anastomoses in small vessels: one-year follow-up

Laser-assisted arterial anastomoses can now be performed with satisfactory short-term patency. This study was undertaken to evaluate patency and aneurysm formation with a 1-year follow-up. A microscopically guided CO2 laser was used to anastomose 1.5 to 2.0 mm carotid arteries in 24 rabbits. Under X6 to X40 magnification, 60 to 70 mW were delivered with a spot size of approximately 0.32 mm. One carotid artery underwent laser anastomosis; the opposite served as a sutured control (10-0 nylon sutures). The 48 end-to-end anastomoses were evaluated for patency and aneurysm formation at 3, 6, and 12 months. Aneurysms were defined as a 1.5 times increase in diameter at the anastomotic site. The vessels underwent microscopic examination. All laser-assisted and sutured anastomoses were patent up to 1 year. At 3 months, one of eight sutured and one of eight laser anastomoses were aneurysmal; stenosis was noted in one laser anastomosis. At 6 months, one of eight laser and 0 of eight sutured anastomoses were aneurysmal. At 12 months, one of eight rabbits had died; of the remaining seven, three of seven laser and zero of seven sutured anastomoses were aneurysmal. In total, five of 23 (21.7%) aneurysms developed with the laser technique and one of 23 (4.3%) with the suture technique (p less than 0.05). Laser-assisted anastomoses are technically feasible, and patency at 1 year is equal to those performed with the suture technique. Aneurysm formation is a consistent problem that demands further investigation.     

Laser welded vascular anastomosis

Summary A comparative study was undertaken to investigate the application of a specially adapted microsurgical Neodymium Yag Laser system with a wavelength of 1,319 m and a CO₂ laser system for laser assisted microvascular end-to-end anastomosis (LAMA) of the rat femoral artery. Conventionally sutured anastomoses served as controls. Postoperative investigations included patency tests, light microscopy and tensile strength measurements. Both laser systems seem to be equally suitable for LAMA: The patency rates do not differ from those of sutured anstomoses and formation of microscopically small aneurysms occurred predominantly in control animals and only once in laser groups. The clamp time needed for LAMA was half the time that was needed for sutured anastomoses. Wound healing in all groups was similar with less fibrotic reactions and less foreign body granulomas in laser groups. At all intervals tensile strength was significantly higher for sutured anastomoses while differences between the CO₂- and the ND: Yag-laser groups were not statistically significant. Potential applications in urology include microvascular anastomoses in erectile dysfunction, pediatric and reconstructive urology.Contains parts of a dissertation     

Laser welded vesicourethral anastomosis in an in vivo canine model: a pilot study

PURPOSE: We evaluated laser welding as an alternative method of forming the vesicourethral anastomosis. MATERIALS AND METHODS: Eight dogs underwent open total prostatectomy, including 4 in which the vesicourethral anastomosis was formed by 830 nm. diode laser welding using a chromophore doped albumin solder and 3 or 4 support sutures. The remaining 4 anastomoses were conventionally formed using 8 interrupted sutures. Acute leakage was tested intraoperatively. The anastomosis of 1 animal per group was assessed on postoperative days 3, 5, 7 and 14 by radiography before sacrifice. Each anastomotic specimen was then tested for leak pressure and examined histologically. RESULTS: There were no leaks during intraoperative testing of laser welded or sutured anastomoses. On radiography there were no leaks in the laser welded group. In 1 control there was slight localized leakage. All anastomoses achieved physiological leak pressures of 70 mm. Hg or greater with 3 of the 4 in the laser welded group recording supraphysiological pressures of greater than 200 mm. Hg. While 3 of the 4 laser welded specimens showed evidence of muscle necrosis, there were no other differences in healing in the 2 groups. CONCLUSIONS: These short-term results suggest that diode laser welded vesicourethral anastomosis is feasible. This technique has the potential to simplify anastomotic formation in laparoscopic radical prostatectomy, shortening operative time. Diode laser welding in this small cohort created an immediate and ongoing watertight anastomosis and, therefore, it may also be an alternative in open radical prostatectomy cases. Further study is needed to assess long-term effects on healing.     

Are mechanical microvascular anastomoses easier to learn than suture anastomoses?

Sutured anastomoses of small vessels are considered difficult to learn. Mechanical anastomosis systems allow a more rapidly performed anastomosis. In order to compare the process of learning to perform sutured and mechanical microvascular anastomoses, two surgeons, with limited microvascular experience, performed 30 aortic and 30 femoral vein anastomoses in 30 Wistar rats. The methods compared were conventional suture, vascular closure system (VCS) and microvascular anastomatic coupler system (MAC). There were no inter-surgeon differences regarding patency or time to perform anastomoses. The average time to perform a suture anastomosis was 39 min (patency 80%). Anastomoses with the VCS system took 24 min (patency 25%), whereas the MAC couplers took 13 min to perform (patency 95%). There was a significant learning effect with sutures, but no obvious reduction in time to perform MAC coupler or VCS clip anastomoses was seen. MAC couplers were easiest to use, and allowed us to perform rapid anastomoses with high patency.     

Low power CO2 laser-assisted microvascular anastomosis: an experimental study

Low power CO2 laser-assisted microvascular anastomosis (LAMA) was used for saphenous artery autotransplantation in 40 rabbits. Eighty end-to-end anastomoses were performed by three methods (conventional interrupted suture, stay suture + laser, laser without stay suture). The long term patency rate in the three types of anastomosis is 93%, 93%, and 100%, respectively. The time needed for the laser procedure is half to one-third of that required for the interrupted suture method. The tensile strength of the bonding site can withstand up to 250 mm Hg of arterial pressure. We have demonstrated that the CO2 laser can be used in microvascular anastomosis with or without stay sutures. Aneurysm formation is a potential risk of LAMA. Accurate coaptation of the transected vessel, precise control of laser energy, and minimal area exposed to the laser beam are the key points for further improving anastomotic quality.     

End-to-side and end-to-end vascular anastomoses with a carbon dioxide laser

This study was designed to compare anastomoses performed with a carbon dioxide laser and conventional anastomoses performed with 7-0 polypropylene suture. In each of 80 rabbits, the divided left carotid artery was anastomosed by a continuous suture technique and the right carotid was anastomosed with a carbon dioxide laser. In each of 40 additional rabbits, both end-to-end and end-to-side laser anastomoses were performed on the same carotid artery. The laser technique involved the placement of three stay sutures (end-to-end technique) or four stay sutures (end-to-side technique) of 7-0 polypropylene and an everting laser seal at a power level of 65 mW. The 1-year overall patency rate was 98% (78/80) in laser anastomoses, 79% (63/80) in suture anastomoses, and 95% (38/40) in combined end-to-end and end-to-side laser anastomoses. Microscopic findings in laser anastomoses demonstrated degeneration of collagen and protein in the adventitia and media, but much less intimal injury than in suture anastomoses, with reendothelialization beginning earlier (within 7 days after anastomosis as compared with 2 to 4 weeks). The tissue tensile strength at 1 hour was less in laser anastomoses than in suture anastomoses, but the laser anastomoses still withstood an intraluminal pressure load of 380 mm Hg. Laser anastomosis improved the microscopic and histologic appearance of the intimal layer, allowing for rapid early reendothelialization and resulting in excellent patency rates.     

An alternative method of vascular anastomosis by laser: experimental and clinical study

In vascular surgery, it is now very difficult to maintain the long-term patency after a conventional vascular anastomosis, especially for small-caliber vessels. A low-energy CO2 laser was experimentally employed to make a vascular anastomosis with only a few sutures. Subsequently, it could be confirmed that optimal conditions for vascular anastomosis by laser were 20-40 mW in output and 6-12 sec/mm in irradiation time. On the other hand, pressure tolerance test as well as tensile strength test and microscopic examinations at the sites of anastomoses by laser were compared with the conventional suture method. There were no significant differences between laser and suture methods. On the basis of the excellent results of this study, the laser was clinically applied for anastomoses of the peripheral vessels in 35 patients. The first clinical laser application in the world was successful in a 44-year-old female patient with chronic renal failure in 1985. All patients are doing well without any complications from vascular anastomosis by laser. From these experimental and clinical studies, it can be concluded that anastomosis by laser should be recommended for small-caliber vessels such as aortocoronary bypass surgery.     

Large-artery welding with a milliwatt carbon dioxide laser

Microvascular laser welding can be effectively used in large-diameter artery techniques. The carotid arteries of 12 anesthetized mongrel dogs were exposed. Following heparinization, the carotid arteries were transected, cleaned along their edges, and repaired on the right side by laser and on the left side by suture. The laser-assisted vascular anastomosis (LAVA) required four stay sutures and laser power for welding. Six-week patency for LAVA vs suture anastomosis was 100% vs 92%, respectively. Anastomotic time requirements were less with LAVA (seven vs 25 minutes). Intimal healing for both techniques immediately demonstrated an intraluminal thrombus, which resolved showing complete endothelial repair by four weeks. The laser seal demonstrated little inflammation compared with the giant cell reaction of suture anastomosis. Immediate wall tensions of 6 to 18 X 10(5) dynes/cm2 were tolerated after both techniques. Laser-assisted vascular anastomosis of large-diameter arteries is feasible, strong, and associated with minimal inflammation.     

Microvascular sutures using a CO2 laser. Initial clinical applications. Apropos of 6 cases

Six microvascular anastomoses were performed using a CO2 low output laser. Time of execution was shorter than with the conventional technique. CO2 laser seems to be promising technique and should allow a better patency rate in microvascular surgery.