Argon laser-assisted anastomoses in medium-size vessels: one-year follow-up

Laser-assisted anastomosis of medium-size vessels can be performed with satisfactory short-term patency. This study was undertaken to evaluate patency and structural integrity up to 1 year. An argon laser was used to make bilateral femoral arteriovenous anastomoses in 12 dogs compared to conventional suture method in another 8 dogs. These anastomoses were evaluated for patency and aneurysm formation at 1 hour; 1, 2, 4, and 8 weeks; and 12 months after surgery. All anastomotic sites were patent and without aneurysmal change or luminal narrowing at all harvesting intervals. Histologic examination revealed that within 1 month laser anastomotic sites were almost completely healed and without intimal hyperplasia. In suture anastomoses, foreign-body reaction remained evident up to 1 year. Use of the argon laser for medium size vessel anastomoses resulted in excellent patency without aneurysm formation or intimal hyperplasia even in the long term. These data suggest promising clinical applications.     

Vascular anastomoses with laser energy

Laser-assisted arterial and venous anastomoses are now feasible. A microscope-guided CO2 laser was used to deliver 60 to 100 mW to anastomose end to end 44 rabbit carotid arteries (1.5 to 2.0 mm) and 27 rabbit vena cavae (4 to 6 mm). These were compared with control arteries repaired with interrupted suture technique. Anastomoses were examined from between 24 hours and 19 weeks. Laser carotid anastomoses yielded 93% patency (41 of 44) and 9% aneurysms (4 of 44), whereas hand-sewn carotid anastomoses produced 91% patency (40 of 44) and no aneurysms. In the vena cava, 26 of 27 laser anastomoses were patent (96%) compared with 19 of 20 (95%) sutured controls. Venous aneurysmal dilatation was seen in 2 of 27 laser (7%) and in 3 of 20 (15%) hand-sewn anastomoses. Histologic examination of laser-assisted anastomoses showed local full-thickness thermal injury. Repair was by fibroblast and myofibroblast proliferation, and luminal cell coverage was complete by 14 days in both laser and sutured repairs. Laser arterial and venous anastomoses are attractive because of their simplicity and rapidity of performance. Their patency is comparable to sutured anastomoses, but arterial aneurysms remain a hazard despite use of extremely low laser energy.     

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.     

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.     

Microvascular anastomoses using an Nd-YAG laser

The authors performed anastomoses of small vessels with the Nd-YAG laser, comparing these with conventional suture anastomoses. Some arteries were sutured with 10-0 nylon with about eight suture sites, and others were held by stay sutures at three points with laser irradiation performed between them. Two surgeons performed the anastomoses in the same way. The first was well-trained and experienced, and the second was technically inexperienced. The authors evaluated clamping time, patency rate, and endoscopic and histologic findings. The patency rate of the first surgeon was 100 percent (30/30) in the suture anastomoses and was 97 percent (29/30) in the laser anastomoses. For the second surgeon, the rates were 60 percent (18/30) in the suture group and 80 percent (24/30) in the laser group. On histologic examination, the suture group showed inflammatory cells around the suture site at the fourth week after the operation. In the laser group, an inflammatory reaction around the suture material was observed, but the other areas recovered. For the experienced surgeon, the patency rate and clamping time of the laser anastomosis provided no statistically significant difference to those of the suture anastomosis. On the other hand, for the inexperienced surgeon, the patency rate of the laser anastomosis was superior to that of the suture anastomosis, and the clamping time of the laser anastomosis was shorter than that of the suture anastomosis. Therefore, the authors concluded that the Nd-YAG laser anastomosis is useful for small vessels.     

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.     

Arterial aneurysm model using laser energy

Continuous wavelength laser energy can be used to perform arterial anastomoses, but all experimental series report an incidence of anastomotic aneurysm formation. To elucidate the mechanism of aneurysm production, controlled injuries of the arterial wall were created with a pulsed CO2 laser beam (40-50 mW). One carotid and one femoral artery of 10 New Zealand rabbits were injured with laser and the contralateral vessel was exposed surgically as a sham operation. At reoperation 8 to 11 weeks later, all 40 arteries were patent. None of the carotid shams, one carotid laser, two femoral shams, and eight femoral laser vessels (80%) were aneurysmal. Histologic examination revealed extensive medial necrosis with fragmentation of the internal elastic lamina in the area of these aneurysms. Femoral vessels were significantly smaller than carotids (P less than 0.001) and the high incidence of aneurysm formation in the former may be due to the relatively greater area of injury. This new model of aneurysm formation after laser injury suggests a need for further study prior to clinical application of this technology, especially in vessels smaller than 2 mm in diameter.     

Enhancement of CO2 laser microvascular anastomoses by fibrin glue

Laser-assisted microvascular anastomoses (LAMA) are characterized by low early bursting strength and high aneurysm rates. The effects of fibrin glue on bursting strength (BS), patency, and aneurysm rate of LAMAs were compared to standard suture and laser anastomosis. Rat femoral arteries (0.9-1.1 mm) were anastomosed end-to-end by three methods: (1) conventionally with 8 to 10 interrupted 10-O nylon sutures; (2) 3 stay sutures and CO2 laser (spot size, 0.275 mm; pulse, 0.2 sec, 80 mW); and (3) cryoprecipitated fibrinogen, 35 mg/cc, crystallized thrombin, CaCl, 20 mg/cc, aprotinin (2000 kIU/cc) applied to weld site in conjunction with laser weld as in (2) above. Patency, aneurysms, and histology were evaluated at 3 weeks, and BS (mm Hg) was measured in six additional vessels at 1 and 24 hr. There was no statistically significant difference in patency rates. Both the suture and fibrin glue groups had significantly higher 1 and 24 hr bursting strengths (P less than 0.05) and significantly lower aneurysm rates (P less than 0.001) than standard laser. There was no significant difference in bursting strength between suture and fibrin glue groups. Histology in the fibrin glue group showed medial damage similar to the LAMA and calcification of aneurysmal vessels. Fibrin glue enhancement of LAMAs produces equal patency, higher early bursting strength, and fewer aneurysms at 3 weeks compared to conventional laser.     

Fibrinolytic activity following laser-assisted vascular anastomosis

New technology has allowed tissue bonding to be feasible using carbon dioxide laser energy. Laser-assisted vascular anastomosis (LAVA) has shown comparable patency results with standard suture anastomosis, but LAVA procedures produce thermally induced transmural structural alterations. To assess functional intimal recovery in LAVA versus sutured vessels, a fibrinolytic slide technique was utilized in 21 rats which had LAVA performed in one femoral artery while the opposite limb underwent a conventional microsuture anastomosis. Conventional anastomosis had persistent fibrinolytic activity while LAVA had return of fibrinolytic activity by 48 hours. Intimal fibrinolysis inhibition following LAVA is reversible and this technique does not lead to an increased incidence of thrombosis.     

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.     

Bursting strength in CO2 laser-assisted microvascular anastomoses

Iliac artery end-to-end anastomoses were performed in 42 Sprague-Dawley rats, divided into seven groups, to determine the welding effects of CO2 laser radiation in microvascular anastomoses. Conventional suture techniques were performed on right iliac arteries, and left iliac arteries were anastomosed with a laser-assisted technique. Bursting strength and diameters of the anastomotic sites were measured at different intervals (from one day to five weeks) post surgery. The anastomotic patency rate was 100 percent in both groups, and the aneurysm rate was only 2 percent in the laser group. Bursting strength was low at one and three days post surgery in both groups; then, it increased gradually until both groups could withstand higher than physiologic pressures. Results of high patency rates, low aneurysm formation, and the ability to withstand pressures higher than physiologic, suggest that the laser-assisted anastomotic technique can play an important role in microvascular surgery.     

Vascular clips have no significant effect on the cellular proliferation, intimal changes, or peak systolic velocity at anastomoses in rabbit vein grafts

OBJECTIVE: This study compares vascular closure staples (VCSs) with conventional sutures in the rabbit carotid vein graft model to determine whether anastomotic technique affects cellular proliferation, blood velocity, or intimal changes when measured over a period of 3 months postoperatively. METHODS: Twenty-six New Zealand White rabbits weighing 3.0-3.2 kg underwent interposition of jugular vein grafts in left carotid arteries. Half of the animals had anastomoses performed with small VCSs (n = 13) and half had anastomoses performed with 8-O interrupted polypropylene suture. Animals were allowed to survive for 1 week (n = 4, VCS; n = 4, suture), 2 weeks (n = 4, VCS; n = 4, suture), and 3 months (n = 5, VCS; n = 5, suture). The peak systolic velocity (PSV) at the distal anastomosis was measured after completion of the graft and again at sacrifice in the 3-month survival groups. At sacrifice, sections were taken from the middle and distal end of the vein graft and the distal carotid artery. Vascular cell proliferation was measured using 5-bromo-2'-deoxyuridine labeling and intimal changes were measured using digitized microscopic images. RESULTS: All 26 grafts were open at the time of sacrifice. PSV at the distal clipped anastomosis was 40.52 cm/s (t = 0) and 34.3 cm/s (t = 3 months, P = 0.31). PSV at the distal sutured anastomosis was 38.30 cm/s (t = 0) and 39.23 cm/s (t = 3 months, P = 0.82). There was no difference between the two techniques at either t = 0 or t = 3 months (P = 0.51 and P = 0.31, respectively). Endothelial cell proliferation and smooth muscle cell proliferation at the anastomosis was highest during the 2 weeks after the procedure, then returned to baseline levels by 3 months. But there was no significant difference between the clipped and sutured groups with respect to vascular cell proliferation postoperatively. The intimal thickness changed significantly in the vein graft at the anastomosis for both the clipped and sutured groups (P = 0.0007 and P = 0.002). But there was no difference when the intimal changes for each technique were compared (P = 0.94). CONCLUSION: No differences were observed when peak systolic velocity, vascular cell proliferation, and intimal changes were compared between sutured and stapled anastomoses in rabbit vein interposition grafts over a period of 3 months after surgery.     

Laser assisted microvascular anastomosis of arteries and veins: laser tissue welding

Using a milliwatt CO2 laser, a series of 160 arteries and 105 veins have been anastomosed in Wistar rats. Three stay sutures and a laser tissue welding technique were used. These were compared with a series of conventionally sutured vessels in terms of patency, speed and ease of procedure, and aneurysm formation. Patency rates of successful first time anastomoses are comparable with conventional suturing methods but the aneurysm rate is higher. Laser assisted anastomosis is faster to learn and perform than conventional suturing, but microsurgical skills are still needed. Despite the large number of variables the laser assisted technique has a high success rate, and work to minimise variables and optimise the laser parameters may improve these results.     

Microvenous end-to-side anastomosis: an experimental study comparing the Unilink system and sutures

A method for mechanical microvascular end-to-side anastomosis is presented and compared to conventional suture technique. Twenty rabbits had their facial veins divided from the jugular veins and reanastomosed end-to-side to the jugular veins, 2 cm cranially to the original bifurcation. The anastomoses were performed on one side of the neck with the Unilink system and on the other side with sutures. At sacrifice at two weeks (10 animals) and at 16 weeks (10 animals), all anastomoses were tested for patency and histologically evaluated. All 40 anastomoses were fully patent. The time required for completion of a mechanical anastomosis was on the average one-fourth the time required for suture anastomosis. No thrombus formation was noted in any of the specimens, but a slight narrowing because of intimal hyperplasia was noted in the recipient vessels in two mechanical anastomoses. It was demonstrated that mechanical anastomoses of small veins end-to-side can be performed in a rapid and safe manner with the Unilink system.     

Strength of microvascular anastomoses: comparison between the unilink anastomotic system and sutures

The Unilink system, a mechanical anastomotic device, was compared with standard suture techniques in terms of anastomotic strength under conditions of uniaxial loading. Twenty-five rabbits underwent Unilink and suture anastomosis of both carotid arteries and facial veins. Animals were sacrificed at 1 hour (five animals), 2 weeks (10 animals), and 16 weeks (10 animals), and all vessels were tested by constant loading in a material testing machine. The maximum load required to disrupt the anastomosis as well as the site of vessel failure were recorded. All 100 anastomoses were fully patent as evaluated by clinical testing. At 1 hour and 2 weeks, the Unilink arterial anastomoses were consistently and significantly stronger than the sutured anastomoses. At 16 weeks the sutured arterial anastomoses were significantly stronger than Unilink. The Unilink anastomoses, however, remained approximately 50% stronger than unoperated normal vessels. No statistical differences were observed in the strength of venous anastomoses at any of the intervals tested. There were no statistical differences in the sites of failure of the vessels under loading (i.e., at the anastomosis or proximal or distal to it) between the two techniques.     

Microvascular anastomosis using a new diode laser system with a contact probe

The aim of the present study was to demonstrate the usefulness of our newly produced diode laser device (an 830-nm output of 190 mW CW) for microvascular end-to-end anastomoses. In the device, diode laser energy is delivered to a contact ceramic tip with a 200-microns diameter output end. Its wavelength is 830 nm and its power 60 mW. This device is small (30 x 25 x 10 cm), lightweight (gross weight 3kg), and easy to manipulate. Compared with conventional microvascular suture anastomosis (CMSA), the time required for the laser-assisted vascular anastomoses (LAVA) was reduced by almost half. Anastomosed portions of both methods were examined 1, 2, 4, 12, and 24 weeks later for patency and aneurysm formation. The patency rate and incidence of aneurysmal formation were the same in both groups. Histological examination revealed that LAVA is superior to CMSA in the smoothness of the inner surface, less inflammatory reaction, and normal collagen and elastic reorientation. The tensile strength and bursting pressure measured immediately after anastomosis demonstrated no significant difference between the two groups. It was concluded that this diode laser contact method may be clinically useful for microvascular surgery.     

Long-term effects of extraluminal dilatation with a rigid circle on arteriovenous anastomotic line in venous grafts transposed into arterial defects

Postanastomotic narrowing resulting from subintimal hyperplasia is a well-known phenomenon. In the current study the authors compared a metallic circle and conventional suture technique in anastomoses performed in two ends of external jugular vein grafts interposed in carotid arteries of rabbits. They recorded the patency rates, fluid flow rates, and histological effects of the circle on the anastomotic line and compared them with conventional suture anastomoses. In 16 rabbits (experimental group) a standard suture was used in both ends of the jugular vein graft transposed to the carotid arteries on one side. On the other side, circle anastomoses were performed on both ends of the vein graft. In an additional 8 rabbits (control group), the anterior jugular veins and carotid arteries were dissected on both sides and left. During postoperative week 12, in 8 rabbits of the experimental group, the flow rates of carotid arteries were measured in vitro, and intraluminal silicone casts were prepared. In the remaining 8 experimental rabbits, carotid angiographies were performed and anastomotic segments were harvested for histological examination. Flow rates were also measured in the control group, and artery and vein segments were harvested. The patency rates of the vein grafts with metallic circle anastomoses were 100%, whereas conventional suture patency was 75% at week 12. Flow rates were significantly higher in the metallic circle-anastomosed vein grafts (74 ml per minute vs. 123 ml per minute, mean values; p < 0.05). Histological examination revealed reduced intimal thickness in the metallic circle anastomoses compared with conventional suture anastomoses. Dilatation of the arteriovenous end-to-end anastomotic line by a rigid circle prevents anastomotic narrowing in the long term.     

镍钛合金吻合夹吻合血管的扫描电镜观察

目的分析镍钛合金吻合夹吻合血管后吻合口部的扫描电镜观察结果.方法新西兰大白兔10只,选取一侧颈动脉以镍钛合金吻合夹行端-端吻合为实验组,另一侧行针线法端-端缝合为对照组.分别于术后1 d、1周、2周、1个月取血管标本,采用扫描电镜观察吻合口部愈合情况.结果所有20条血管均吻合成功,吻合夹法用时(8±3.2)min明显少于针线法(15±4.5)min.镍钛合金吻合夹吻合血管后吻合口部内皮细胞再生早,内膜更为光滑.结论镍钛合金血管吻合夹吻合血管快速、安全、可靠,具有良好的应用前景.     

Comparison of laser vascular welding,interrupted sutures,and continuous sutures in growing vascular anastomoses

Background and Objectives: The argon laser-assisted vascular anastomosis may solve the problems of conventional sutured anastomosis, such as vascular stenosis and arrest of growth owing to a foreign-body reaction to suture material. Study Design/Materials and Methods: Twelve argon laser-assisted vascular anastomoses, seven conventional anastomoses with interrupted sutures, and five conventional anastomoses with continuous sutures were performed in 12 young mongrel dogs. Results: Five months later, the external diameter at the anastomosis had increased 70.5% in the laser group, 67.0% in the interrupted suture group, and 22.9% in the continuous suture group. Histological examination of the laser-assisted anastomoses showed almost complete healing, with no granulomatous response around the anastomotic site. In the interrupted suture group, marked scaring and foreign body reactions were observed on the vessel wall at the site of the anastomosis. The continuous suture group showed more remarkable disorientation of the vascular layer and intimal hyperplasia than the interrupted suture group. Conclusion: Vascular anastomosis using the argon laser offers advantages over the conventional procedure in growing vessels.     

Laser-assisted vasovasostomy in the rat. Comparison of CO2 and neodymium:YAG laser techniques

A comparative study was undertaken to investigate the Nd:YAG and CO2 laser systems for laser-assisted vasovasostomies (LAVs). In 32 rats 64 vasovasostomies were performed, either conventionally sutured (CSV) or laser-welded (LAV-CO2 and LAV-Nd:YAG). Postoperative investigations included patency tests, gross examination, light and electron microscopy. The highest rate of sperm granulomas (50%) and the lowest patency rate (50%) was seen in the LAV-Nd:YAG group. LAV-CO2 showed the lowest rate of sperm granulomas (12.5%) and had a patency rate (82%) which was comparable to that of CSV (88%). Laser-assisted vas anastomosis is time saving and technically easy to perform. Contrary to microvascular anastomoses, where both laser types offer the same results, vas anastomosis is better done using a CO2 laser system.