Amado Ruiz-Razura, Gary S. Branfman, Ma Lan, and Benjamin E. Cohen
LASER-ASSISTED MICROSURGICAL ANASTOMOSES IN
ABSTRACT Technological advances have made CO2 laser-assisted microvascular anastomoses (LAMA) feasible. This study seeks to compare results of LAMA versus CSMA (conventional suture microsurgical anastomosis) in traumatized vessels. Using a rat model, femoral arteries and veins were either crushed and transected or divided by avulsion and then repaired by either LAMA or CSMA. LAMA resulted in higher patency rates than CSMA at early postoperative observation periods. With time, the patency rates improved in both groups and, by the end of the study, the patency rates were equivalent. These findings indicate that the laser technique may be a better option when working with traumatized vessels because of the critical nature of early patency rates. The improved results may be due to a reduction of suture material at the anastomotic site when using the laser technique. Some physiologic aspects of vessel thrombosis, recanalization, and the role of collateral circulation are discussed. The laser, introduced by Maimon over twenty-five years ago 1 is now used in many clinical disciplines. Dermatologists, ophthalmologists, neurosurgeons, and otolaryngologists have adopted the use of laser primarily as a tool of ablation. 2 - 5 First attempts at laser-assisted vascular anastomoses (vessel edge "spot-welding") achieved minimal success. 6 Subsequent efforts with improved equipment and more refined techniques have shown the idea to be feasible. 78 In contrast to precise surgical division of an artery or vein, vessel division in clinical trauma cases often has a crush or avulsion component. Ideally, resection of damaged vessel ends is performed prior to anastomosis. However, histologic damage may extend beyond the area of obvious gross trauma and intact adventitia may mask intimal contusion. 910 Working with these damaged vessels often results in thrombosis and failure. The CO2 laser-assisted microvascular anastomosis requires far fewer sutures than does the conventional method. We wondered whether this reduction in foreign material might contribute to higher patency rates in these damaged vessels. The experiments re-
ported here were designed to study anastomotic patency rates in traumatically divided vessels repaired by the conventional or laser-assisted method.
MATERIALS AND METHODS Forty Sprague-Dawley rats weighing between 250 and 300 gm were used for the experiments. Anesthesia was obtained with an intraperitoneal injection of a mixture of butorphanol tartrate, chloral hydrate, and sodium pentobarbital. The femoral vessels were exposed and isolated between the inguinal ligament and superficial epigastric vessels with the aid of an operating microscope. All minor branches were cauterized and divided. Model 1 (Crush Injury). After applying microvascular occluding clamps proximally and distally, a smoothjawed needle holder was applied across the midpoint of the exposed femoral artery or vein. Constant pressure was applied for 3 sec at two ratchet clicks. The vessels were then transected through the crushed 55
Division of Plastic Surgery and Microsurgery, St. Joseph Hospital, Houston Reprint requests-. Dr. Ruiz-Razura, Div. of Plastic Surgery and Microsurgery, St. Joseph Hospital, 1919 La Branch, Houston, TX 77002 Accepted for publication October 6, 1989 Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
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TRAUAAATIZED BLOOD VESSELS
zone. Excess adventitia was trimmed but the vessel ends were not resected (Fig. I). Control (all-suture) vessels were anastomosed using nine 10-0 interrupted monofilament nylon sutures. Experimental (laserassisted) anastomoses were performed by placing three interrupted 10-0 monofilament nylon sutures at 120° intervals, thereby dividing the circumference into three sections. The vessel edges of each section were sequentially coapted by applying slight outward tension on the appropriate stay sutures. The coapted vessel edges were then welded using the Bioquantum Technologies 7600 Microsurgical CO2 Laser (Fig. 2). Energy was delivered by continuous technique using 0.08 watts for arterial fusion and 0.07 watts for venous fusion. In this fashion, the three segments of vessel circumference were fused, thereby completing the anastomosis. Model 2 (Avulsion Injury). The femoral vessels
were isolated and exposed as described above. Two smooth-jawed needle holders were applied 2 mm
Figure 1. Crush Injury. A, A smooth-jawed needle holder is applied to the midpoint of the vessel for 2 sec at three ratchet clicks. B, Transection of the vessel is performed at the midpoint of the injury.
Laser
56
Figure 2. Laser-assisted microsurgical anastomosis. Gentle outward tension is applied to two of the three stay sutures. The potion of vessel circumference between these two sutures is "spot-welded" with the laser. This process is then applied to the remaining two-thirds of vessel circumference.
JANUARY 1990
apart at the midpoint of the exposed vessel. Subsequent pulling of the needle holders in opposite directions was performed until the vessel was torn apart. In addition to the avulsion, crush injury was present proximal and distal to the transection where the needle holders were applied. Sharp excision of less than 1 mm of vessel end was performed, leaving significant traumatized tissue at the vessel ends (Fig. 3). These vessels were then joined using either the conventional or laserassisted method as described above. Anastomotic Patency. Evaluation of anastomotic patency was performed at the completion of the procedure and again in each animal at two, seven, 14, 21, and 28 days postoperatively. The animals were anesthetized and the vessels were exposed and directly examined. To assess patency, the standard empty and refill test was used.'' The vessel was occluded with a pair of forceps distal to the anastomosis. A second pair of forceps was applied next to and distal to the first pair and then moved distally to gently "milk" the blood out of a short segment. The proximal forceps were then released, permitting the emptied segment to refill if the anastomosis was patent. Patency was confirmed by at least two examiners. Nonpatent anastomoses were not subjected to any manipulations or attempts to establish flow.
RESULTS Model 1 (Crush \njury). The immediate patency rates using the laser-assisted anastomosis were 100 percent for arteries and 90 percent for veins while with the conventional all-suture method, patency rates were 95 percent for arteries and 85 percent for veins. On day 2 the patency rates for lasered arteries and veins were 80 percent and 65 percent, compared to 65 percent and 45 percent for the conventionally repaired vessels. At one week, the laser-assisted artery and vein
Figure 3. Avulsion Injury. A, Two smooth-jawed needle holders are applied and pulled in opposite directions. B, Pulling is continued until the vessel is torn apart. C, Minimal vessel end is trimmed, leaving a significant amount of traumatized tissue intact.
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JOURNAL OF RECONSTRUCTIVE MICROSURGERY/VOLUME 6, NUMBER 1
LASER-ASSISTED ANASTOMOSES/RUIZ-RAZURA, BRANFMAN, LAN, COHEN
Table 1. Arterial Patency Rate Following Crush Injury Postoperative Interval
Patency Rates LAMA 100% 80% 95% 100% 100% 100%
Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
(20/20) (16/20) (19/20) (20/20) (20/20) (20/20)
CSMA 95% 65% 80% 100% 100% 100%
(19/20) (13/20) (16/20) (20/20) (20/20) (20/20)
p Value 54 54
Figure 4. Arterial crush injury, LAMA, four weeks. The anastomotic site at the laser weld (arrow) and stay sutures (arrows) is well healed and covered with neointima. (Original magnification. 5 0 x ; Weigert-van Geison's elastin stain.)
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patency rates were 95 percent and 85 percent while 80 percent of arteries and 70 percent of veins repaired with the conventional all-suture method were patent. Subsequent weekly examinations showed increasing patency levels in all groups. After four weeks, all anastomoses were patent regardless of vessel type (artery or vein) or technique employed. Tables 1 and 2 detail this data. Figure 4 illustrates the histologic appearance of an artery four weeks after repair with LAMA. Model 2 {Avulsion Injury). The immediate patency rates for the laser groups were 95 percent and 90 percent for arteries and veins, respectively. The conventional all-suture anastomoses also revealed patency rates of 95 percent for arteries and 90 percent for veins. Two days later, reexplorations revealed 85 percent and 35 percent patency rates for lasered arteries and veins, respectively, compared to 45 percent and 10 percent for conventional all-suture anastomoses. Subsequent reexplorations at one-week intervals revealed improvement in patency rates in both groups and, at one month, patency rates approaching 100 percent were present in all vessels. Tables 3 and 4 display these data. The histologic appearance four weeks after LAMA is depicted in Figure 5. Table 5 and Figure 6 show the pooled data from all groups at all intervals.
Table 3. Arterial Patency Rate Following Avulsion Injury Postoperative Interval Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
Patency Rates LAMA 95% 85% 85% 90% 95% 100%
(19/20) (17/20) (17/20) (18/20) (19/20) (20/20)
CSMA 95% 45% 50% 55% 65% 95%
(19/20) (9/20) (10/20) (11/20) (13/20) (19/20)
p Value .014 .046 .07 .041
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
1
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss J: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two Table 4. Venous Patency Rate Following Avulsion Injury anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval. vnctnnomtu,* Patency Rates Interval Table 2.
Venous Patency Rate Following Crush Injury
vnctnn»mt!t,* Interval Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
Patency Rates LAMA 90% 65% 85% 100% 100% 100%
(18/20) (13/20) (17/20) (20/20) (20/20) (20/20)
CSMA 85% 50% 70% 95% 100% 100%
(17/20) (10/20) (14/20) (19/20) (20/20) (20/20)
p Value 1 .5 1 1 1 1
Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
LAMA 90% 35% 55% 75% 85% 100%
(18/20) (7/20) (11/20) (15/20) (17/20) (20/20)
CSMA 90% 10% 40% 50% 70% 90%
(18/20) (2/20) (8/20) (10/20) (14/20) (18/20)
p Value 1 .16 .5 .15 .54 .48
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss J: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
57
JOURNAL OF RECONSTRUCTIVE MICROSURGERY/VOLUME 6, NUMBER 1
JANUARY 1990
DISCUSSION In this study, vessels were either crushed and divided or pulled apart with an avulsive maneuver. All vessels were then repaired using either conventional all-suture microvascular anastomoses or laser-assisted microvascular anastomoses. Anastomotic patency rates v were determined immediately and at several intervals postoperatively. Early exploration revealed significant rates of occlusion in both the conventionally-repaired and laser-assisted groups. The laser method exhibited statistically significant superiority at two days, one week, and three weeks when used to repair avulsed arteries, and at two days, one week, two weeks, and Figure 5. Arterial avulsion injury, LAMA, four weeks. The laser anastomotic site (arrow) is well healed with neoin- three weeks when the data from all vessels (arteries tima and fibrous adventitial scar tissue filling the wound and veins) injured by either method were combined. In gaps. (Original magnification. 50X; Weigert-van Geison's no instance did the patency rates of CSMA surpass that elastin stain.) of LAMA. In this model, collateral flow around the obstructed vessel provides circulation to distal tissues. In replantation and free tissue transfer cases, no such Table 5. Patency Rates of All collateral vessels are present in the acute phase, and Traumatized Blood Vessels survival depends entirely on continuous anastomotic Patency Rates Postoperative patency. Thus, the results in the first 48 hr in which the Interval LAMA p Value greatest differences between LAMA and CSMA are CSMA Immediate 94% (75/80) 91% (73/80) .78 observed are, in fact, the most clinically relevant and 2 days 66% (53/80) .001 43% (34/80) provide the strongest argument for the use of LAMA in 1 week 80% (64/80) .006 60% (48/80) the trauma setting. In both the conventional and laser 2 weeks 91% (73/80) 75% (60/80) .008 groups, subsequent weekly reexplorations revealed 3 weeks 95% (76/80) .001 84% (67/80) steadily improving patency rates and, by the end of the 4 weeks 100% (80/80) 96% (77/80) .25 month, excellent patency rates were noted irrespective Note: LAMA = laser-assisted microsurgical anastomosis; of vessel type, mechanism of injury, or anastomotic CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates andtechnique. Proportions, New York: John Wiley and Sons, 1981) to compare the two The steady improvement in patency rates obanastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval. served from the first week onward can be explained by
55
PATENCY RATES (% Patent)
POST-OPERATIVE TIME INTERVAL
Figure 6. Patency rates of 160 traumatized blood vessels at subsequent reexplorations after repair by LAMA (80 vessels) or CSMA (80 vessels).
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7' * i I
LASER-ASSISTED ANASTOMOSES/RUIZ-RAZURA, BRANFMAN, LAN, COHEN
REFERENCES 1. 2. 3. 4.
5. 6.
7. 8. 9.
10. 11. 12.
13. 14. 15.
16. 17.
18.
Maimon TH: Stimulated optical radiation in ruby lasers. Nature 187:493, 1960 Goldman I, Hornby P, Long C: Effect of the laser on the skin. I Invest Dermatol 42:231, 1964 L'Esperence F Jr An ophthalmic argon laser photocoagulator system: Design, construction, and laboratory investigation. Trans Am Ophthmol Soc 66:827, 1968 Stellar S: Experimental studies with carbon dioxide laser as a neurosurgical instrument. Med Biol Eng Comput 8:549, 1970 Jacko GL: Laser surgery of the vocal cords—An experimental study with carbon dioxide laser. Laryngoscope 82:2204, 1972 Yahr WZ, Strully KJ: Blood vessel anastomosis by laser and other biomedical applications. I Assoc Adv Med Instr 1:28, 1966 Neblett, CR, Morris JR, Thomsen S: Laser-assisted microsurgical anastomosis. Neurosurgery 19:914, 1986 Ruiz-Razura A, Lan M, Cohen BE: The laser-assisted end-toside microvascular anastomosis. Plast Reconstr Surg 83: 512, 1989 Chen ZW, Yang DY, Chang DS, et al: Microsurgery and Pathology. Microsurgery Shanghai Scientific and Technical PublishersBerlin: Springer Verlag, 1982 Glover MG, Seaber AV, Urbaniak I: Arterial intimal damage in avulsion and crush injuries in rat limbs. I Reconstr Microsurg 1:247, 1985 Acland RD: Microsurgery Practice Manual. St. Louis: C.V. Mosby Company, 1980 Gorseman J, Fletcher AP, Alkjaersign N, Sherry S: Enzymatic lysis of plasma clots: The influence of fibrin on lysis rates. Arch Biochem Biophys 120:654, 1967 Freiman AH, Bang NU, Grossi CE, Clifton EE: Factors affecting the formation and dissolution of experimental thrombi. Am ) Cardiol 6:426, 1960 Sauter RD, Fletcher FW, Emanuel A, et al: Complete resolution of pulmonary thromboembolism. JAMA 189:948, 1964 Ruiz-Razura A, Lan M, Cohen BE: Bursting strength in CO2 laser-assisted microvascular anastomoses. | Reconstr Microsurg 4:291, 1988 McCarthy W|, Hartz RS, lames ST, et al: Vascular anastomoses with laser energy. I Vase Surg 3:32, 1986 Ruiz-Razura A, Casso D, Cohen BE: Laser-assisted vascular anastomosis: Cause of aneurysm formation and prevention. Paper presented at the South Texas Chapter, American College of Surgeons, lanuary 30, 1987, Houston, Texas. Frazier OH, Shehab SA, Zirl R. Anastomosis of bypass grafts using a low-powered CO2 laser. Laser Med Surg 9:30, 1989
This study was funded in part by The American Society for Laser Medicine and Surgery, Wausau, Wisconsin. This study received the 1989 Laser Award from the American Society of Plastic and Reconstructive Surgeons-Laser Committee; ASPRS Annual Meeting, San Francisco, California.
59
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the natural sequelae to vessel thrombosis. The reestablishment of flow through an occluded vessel develops initially from the synergistic effects of plasmininduced fibrinolysis and clot retraction,12 after which time recanalization occurs. These changes can result in some restoration of vascular flow within hours of initial thrombus formation. Common clinical examples that illustrate these phenomena include the recanalization of peripheral veins after thrombosis and the rapid and complete disappearance of pulmonary emboli. 1314 Aspects of LAMA worth noting include excellent tensile strength 7 and an ability to withstand supraphysiologic bursting strengths. 15 Clean-cut vessels can be repaired with the laser method using one-third the sutures and can result in patency rates equivalent or superior to conventional repair. The most consistently noted advantage of LAMA is its time-saving quality. The laser anastomosis can reduce operating time by 50 percent and consistent leak-free anastomoses are obtained. 716 In our experience, a laser-assisted anastomosis requires less than 10 min to perform, in contrast to the more than 20 min needed when using conventional all-suture technique. When performing the replantation of multiple digits, this can result in a considerable saving of time. Disadvantages associated with LAMA include the expense of purchasing and maintaining the apparatus and the time and cost of training physicians in its use. Some studies have implicated the laser as a cause of aneurysm formation but in our study, no aneurysms were found grossly or microscopically on histologic section. Avoidance of aneurysm formation is related to reduction of tension at the anastomotic site, care not to use excessive heat on vessel edges, and delivering the laser energy by a continuous mode. 17 Questions regarding whether or not conclusions based on studies in rat vessels are applicable to larger animals with thicker-walled vessels have been raised. Recent investigators have demonstrated the feasibility of CO2 laser-assisted anastomoses in domestic pigs with vessels much more similar to humans. 18 At the present time, enough encouraging work has been done to warrant continued investigation of this tool and possible application in the clinical setting.
LASER-ASSISTED MICROSURGICAL ANASTOMOSES IN
ABSTRACT Technological advances have made CO2 laser-assisted microvascular anastomoses (LAMA) feasible. This study seeks to compare results of LAMA versus CSMA (conventional suture microsurgical anastomosis) in traumatized vessels. Using a rat model, femoral arteries and veins were either crushed and transected or divided by avulsion and then repaired by either LAMA or CSMA. LAMA resulted in higher patency rates than CSMA at early postoperative observation periods. With time, the patency rates improved in both groups and, by the end of the study, the patency rates were equivalent. These findings indicate that the laser technique may be a better option when working with traumatized vessels because of the critical nature of early patency rates. The improved results may be due to a reduction of suture material at the anastomotic site when using the laser technique. Some physiologic aspects of vessel thrombosis, recanalization, and the role of collateral circulation are discussed. The laser, introduced by Maimon over twenty-five years ago 1 is now used in many clinical disciplines. Dermatologists, ophthalmologists, neurosurgeons, and otolaryngologists have adopted the use of laser primarily as a tool of ablation. 2 - 5 First attempts at laser-assisted vascular anastomoses (vessel edge "spot-welding") achieved minimal success. 6 Subsequent efforts with improved equipment and more refined techniques have shown the idea to be feasible. 78 In contrast to precise surgical division of an artery or vein, vessel division in clinical trauma cases often has a crush or avulsion component. Ideally, resection of damaged vessel ends is performed prior to anastomosis. However, histologic damage may extend beyond the area of obvious gross trauma and intact adventitia may mask intimal contusion. 910 Working with these damaged vessels often results in thrombosis and failure. The CO2 laser-assisted microvascular anastomosis requires far fewer sutures than does the conventional method. We wondered whether this reduction in foreign material might contribute to higher patency rates in these damaged vessels. The experiments re-
ported here were designed to study anastomotic patency rates in traumatically divided vessels repaired by the conventional or laser-assisted method.
MATERIALS AND METHODS Forty Sprague-Dawley rats weighing between 250 and 300 gm were used for the experiments. Anesthesia was obtained with an intraperitoneal injection of a mixture of butorphanol tartrate, chloral hydrate, and sodium pentobarbital. The femoral vessels were exposed and isolated between the inguinal ligament and superficial epigastric vessels with the aid of an operating microscope. All minor branches were cauterized and divided. Model 1 (Crush Injury). After applying microvascular occluding clamps proximally and distally, a smoothjawed needle holder was applied across the midpoint of the exposed femoral artery or vein. Constant pressure was applied for 3 sec at two ratchet clicks. The vessels were then transected through the crushed 55
Division of Plastic Surgery and Microsurgery, St. Joseph Hospital, Houston Reprint requests-. Dr. Ruiz-Razura, Div. of Plastic Surgery and Microsurgery, St. Joseph Hospital, 1919 La Branch, Houston, TX 77002 Accepted for publication October 6, 1989 Copyright © 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
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TRAUAAATIZED BLOOD VESSELS
zone. Excess adventitia was trimmed but the vessel ends were not resected (Fig. I). Control (all-suture) vessels were anastomosed using nine 10-0 interrupted monofilament nylon sutures. Experimental (laserassisted) anastomoses were performed by placing three interrupted 10-0 monofilament nylon sutures at 120° intervals, thereby dividing the circumference into three sections. The vessel edges of each section were sequentially coapted by applying slight outward tension on the appropriate stay sutures. The coapted vessel edges were then welded using the Bioquantum Technologies 7600 Microsurgical CO2 Laser (Fig. 2). Energy was delivered by continuous technique using 0.08 watts for arterial fusion and 0.07 watts for venous fusion. In this fashion, the three segments of vessel circumference were fused, thereby completing the anastomosis. Model 2 (Avulsion Injury). The femoral vessels
were isolated and exposed as described above. Two smooth-jawed needle holders were applied 2 mm
Figure 1. Crush Injury. A, A smooth-jawed needle holder is applied to the midpoint of the vessel for 2 sec at three ratchet clicks. B, Transection of the vessel is performed at the midpoint of the injury.
Laser
56
Figure 2. Laser-assisted microsurgical anastomosis. Gentle outward tension is applied to two of the three stay sutures. The potion of vessel circumference between these two sutures is "spot-welded" with the laser. This process is then applied to the remaining two-thirds of vessel circumference.
JANUARY 1990
apart at the midpoint of the exposed vessel. Subsequent pulling of the needle holders in opposite directions was performed until the vessel was torn apart. In addition to the avulsion, crush injury was present proximal and distal to the transection where the needle holders were applied. Sharp excision of less than 1 mm of vessel end was performed, leaving significant traumatized tissue at the vessel ends (Fig. 3). These vessels were then joined using either the conventional or laserassisted method as described above. Anastomotic Patency. Evaluation of anastomotic patency was performed at the completion of the procedure and again in each animal at two, seven, 14, 21, and 28 days postoperatively. The animals were anesthetized and the vessels were exposed and directly examined. To assess patency, the standard empty and refill test was used.'' The vessel was occluded with a pair of forceps distal to the anastomosis. A second pair of forceps was applied next to and distal to the first pair and then moved distally to gently "milk" the blood out of a short segment. The proximal forceps were then released, permitting the emptied segment to refill if the anastomosis was patent. Patency was confirmed by at least two examiners. Nonpatent anastomoses were not subjected to any manipulations or attempts to establish flow.
RESULTS Model 1 (Crush \njury). The immediate patency rates using the laser-assisted anastomosis were 100 percent for arteries and 90 percent for veins while with the conventional all-suture method, patency rates were 95 percent for arteries and 85 percent for veins. On day 2 the patency rates for lasered arteries and veins were 80 percent and 65 percent, compared to 65 percent and 45 percent for the conventionally repaired vessels. At one week, the laser-assisted artery and vein
Figure 3. Avulsion Injury. A, Two smooth-jawed needle holders are applied and pulled in opposite directions. B, Pulling is continued until the vessel is torn apart. C, Minimal vessel end is trimmed, leaving a significant amount of traumatized tissue intact.
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JOURNAL OF RECONSTRUCTIVE MICROSURGERY/VOLUME 6, NUMBER 1
LASER-ASSISTED ANASTOMOSES/RUIZ-RAZURA, BRANFMAN, LAN, COHEN
Table 1. Arterial Patency Rate Following Crush Injury Postoperative Interval
Patency Rates LAMA 100% 80% 95% 100% 100% 100%
Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
(20/20) (16/20) (19/20) (20/20) (20/20) (20/20)
CSMA 95% 65% 80% 100% 100% 100%
(19/20) (13/20) (16/20) (20/20) (20/20) (20/20)
p Value 54 54
Figure 4. Arterial crush injury, LAMA, four weeks. The anastomotic site at the laser weld (arrow) and stay sutures (arrows) is well healed and covered with neointima. (Original magnification. 5 0 x ; Weigert-van Geison's elastin stain.)
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patency rates were 95 percent and 85 percent while 80 percent of arteries and 70 percent of veins repaired with the conventional all-suture method were patent. Subsequent weekly examinations showed increasing patency levels in all groups. After four weeks, all anastomoses were patent regardless of vessel type (artery or vein) or technique employed. Tables 1 and 2 detail this data. Figure 4 illustrates the histologic appearance of an artery four weeks after repair with LAMA. Model 2 {Avulsion Injury). The immediate patency rates for the laser groups were 95 percent and 90 percent for arteries and veins, respectively. The conventional all-suture anastomoses also revealed patency rates of 95 percent for arteries and 90 percent for veins. Two days later, reexplorations revealed 85 percent and 35 percent patency rates for lasered arteries and veins, respectively, compared to 45 percent and 10 percent for conventional all-suture anastomoses. Subsequent reexplorations at one-week intervals revealed improvement in patency rates in both groups and, at one month, patency rates approaching 100 percent were present in all vessels. Tables 3 and 4 display these data. The histologic appearance four weeks after LAMA is depicted in Figure 5. Table 5 and Figure 6 show the pooled data from all groups at all intervals.
Table 3. Arterial Patency Rate Following Avulsion Injury Postoperative Interval Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
Patency Rates LAMA 95% 85% 85% 90% 95% 100%
(19/20) (17/20) (17/20) (18/20) (19/20) (20/20)
CSMA 95% 45% 50% 55% 65% 95%
(19/20) (9/20) (10/20) (11/20) (13/20) (19/20)
p Value .014 .046 .07 .041
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
1
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss J: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two Table 4. Venous Patency Rate Following Avulsion Injury anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval. vnctnnomtu,* Patency Rates Interval Table 2.
Venous Patency Rate Following Crush Injury
vnctnn»mt!t,* Interval Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
Patency Rates LAMA 90% 65% 85% 100% 100% 100%
(18/20) (13/20) (17/20) (20/20) (20/20) (20/20)
CSMA 85% 50% 70% 95% 100% 100%
(17/20) (10/20) (14/20) (19/20) (20/20) (20/20)
p Value 1 .5 1 1 1 1
Immediate 2 days 1 week 2 weeks 3 weeks 4 weeks
LAMA 90% 35% 55% 75% 85% 100%
(18/20) (7/20) (11/20) (15/20) (17/20) (20/20)
CSMA 90% 10% 40% 50% 70% 90%
(18/20) (2/20) (8/20) (10/20) (14/20) (18/20)
p Value 1 .16 .5 .15 .54 .48
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss J: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
Note: LAMA = laser-assisted microsurgical anastomosis; CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates and Proportions, New York: John Wiley and Sons, 1981) to compare the two anastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval.
57
JOURNAL OF RECONSTRUCTIVE MICROSURGERY/VOLUME 6, NUMBER 1
JANUARY 1990
DISCUSSION In this study, vessels were either crushed and divided or pulled apart with an avulsive maneuver. All vessels were then repaired using either conventional all-suture microvascular anastomoses or laser-assisted microvascular anastomoses. Anastomotic patency rates v were determined immediately and at several intervals postoperatively. Early exploration revealed significant rates of occlusion in both the conventionally-repaired and laser-assisted groups. The laser method exhibited statistically significant superiority at two days, one week, and three weeks when used to repair avulsed arteries, and at two days, one week, two weeks, and Figure 5. Arterial avulsion injury, LAMA, four weeks. The laser anastomotic site (arrow) is well healed with neoin- three weeks when the data from all vessels (arteries tima and fibrous adventitial scar tissue filling the wound and veins) injured by either method were combined. In gaps. (Original magnification. 50X; Weigert-van Geison's no instance did the patency rates of CSMA surpass that elastin stain.) of LAMA. In this model, collateral flow around the obstructed vessel provides circulation to distal tissues. In replantation and free tissue transfer cases, no such Table 5. Patency Rates of All collateral vessels are present in the acute phase, and Traumatized Blood Vessels survival depends entirely on continuous anastomotic Patency Rates Postoperative patency. Thus, the results in the first 48 hr in which the Interval LAMA p Value greatest differences between LAMA and CSMA are CSMA Immediate 94% (75/80) 91% (73/80) .78 observed are, in fact, the most clinically relevant and 2 days 66% (53/80) .001 43% (34/80) provide the strongest argument for the use of LAMA in 1 week 80% (64/80) .006 60% (48/80) the trauma setting. In both the conventional and laser 2 weeks 91% (73/80) 75% (60/80) .008 groups, subsequent weekly reexplorations revealed 3 weeks 95% (76/80) .001 84% (67/80) steadily improving patency rates and, by the end of the 4 weeks 100% (80/80) 96% (77/80) .25 month, excellent patency rates were noted irrespective Note: LAMA = laser-assisted microsurgical anastomosis; of vessel type, mechanism of injury, or anastomotic CSMA = conventional suture microsurgical anastomosis; p values obtained using McNemar's test (Fleiss I: Statistical Methods for Rates andtechnique. Proportions, New York: John Wiley and Sons, 1981) to compare the two The steady improvement in patency rates obanastomotic procedures for each blood vessel type, mechanism of injury and postoperative time interval. served from the first week onward can be explained by
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PATENCY RATES (% Patent)
POST-OPERATIVE TIME INTERVAL
Figure 6. Patency rates of 160 traumatized blood vessels at subsequent reexplorations after repair by LAMA (80 vessels) or CSMA (80 vessels).
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7' * i I
LASER-ASSISTED ANASTOMOSES/RUIZ-RAZURA, BRANFMAN, LAN, COHEN
REFERENCES 1. 2. 3. 4.
5. 6.
7. 8. 9.
10. 11. 12.
13. 14. 15.
16. 17.
18.
Maimon TH: Stimulated optical radiation in ruby lasers. Nature 187:493, 1960 Goldman I, Hornby P, Long C: Effect of the laser on the skin. I Invest Dermatol 42:231, 1964 L'Esperence F Jr An ophthalmic argon laser photocoagulator system: Design, construction, and laboratory investigation. Trans Am Ophthmol Soc 66:827, 1968 Stellar S: Experimental studies with carbon dioxide laser as a neurosurgical instrument. Med Biol Eng Comput 8:549, 1970 Jacko GL: Laser surgery of the vocal cords—An experimental study with carbon dioxide laser. Laryngoscope 82:2204, 1972 Yahr WZ, Strully KJ: Blood vessel anastomosis by laser and other biomedical applications. I Assoc Adv Med Instr 1:28, 1966 Neblett, CR, Morris JR, Thomsen S: Laser-assisted microsurgical anastomosis. Neurosurgery 19:914, 1986 Ruiz-Razura A, Lan M, Cohen BE: The laser-assisted end-toside microvascular anastomosis. Plast Reconstr Surg 83: 512, 1989 Chen ZW, Yang DY, Chang DS, et al: Microsurgery and Pathology. Microsurgery Shanghai Scientific and Technical PublishersBerlin: Springer Verlag, 1982 Glover MG, Seaber AV, Urbaniak I: Arterial intimal damage in avulsion and crush injuries in rat limbs. I Reconstr Microsurg 1:247, 1985 Acland RD: Microsurgery Practice Manual. St. Louis: C.V. Mosby Company, 1980 Gorseman J, Fletcher AP, Alkjaersign N, Sherry S: Enzymatic lysis of plasma clots: The influence of fibrin on lysis rates. Arch Biochem Biophys 120:654, 1967 Freiman AH, Bang NU, Grossi CE, Clifton EE: Factors affecting the formation and dissolution of experimental thrombi. Am ) Cardiol 6:426, 1960 Sauter RD, Fletcher FW, Emanuel A, et al: Complete resolution of pulmonary thromboembolism. JAMA 189:948, 1964 Ruiz-Razura A, Lan M, Cohen BE: Bursting strength in CO2 laser-assisted microvascular anastomoses. | Reconstr Microsurg 4:291, 1988 McCarthy W|, Hartz RS, lames ST, et al: Vascular anastomoses with laser energy. I Vase Surg 3:32, 1986 Ruiz-Razura A, Casso D, Cohen BE: Laser-assisted vascular anastomosis: Cause of aneurysm formation and prevention. Paper presented at the South Texas Chapter, American College of Surgeons, lanuary 30, 1987, Houston, Texas. Frazier OH, Shehab SA, Zirl R. Anastomosis of bypass grafts using a low-powered CO2 laser. Laser Med Surg 9:30, 1989
This study was funded in part by The American Society for Laser Medicine and Surgery, Wausau, Wisconsin. This study received the 1989 Laser Award from the American Society of Plastic and Reconstructive Surgeons-Laser Committee; ASPRS Annual Meeting, San Francisco, California.
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the natural sequelae to vessel thrombosis. The reestablishment of flow through an occluded vessel develops initially from the synergistic effects of plasmininduced fibrinolysis and clot retraction,12 after which time recanalization occurs. These changes can result in some restoration of vascular flow within hours of initial thrombus formation. Common clinical examples that illustrate these phenomena include the recanalization of peripheral veins after thrombosis and the rapid and complete disappearance of pulmonary emboli. 1314 Aspects of LAMA worth noting include excellent tensile strength 7 and an ability to withstand supraphysiologic bursting strengths. 15 Clean-cut vessels can be repaired with the laser method using one-third the sutures and can result in patency rates equivalent or superior to conventional repair. The most consistently noted advantage of LAMA is its time-saving quality. The laser anastomosis can reduce operating time by 50 percent and consistent leak-free anastomoses are obtained. 716 In our experience, a laser-assisted anastomosis requires less than 10 min to perform, in contrast to the more than 20 min needed when using conventional all-suture technique. When performing the replantation of multiple digits, this can result in a considerable saving of time. Disadvantages associated with LAMA include the expense of purchasing and maintaining the apparatus and the time and cost of training physicians in its use. Some studies have implicated the laser as a cause of aneurysm formation but in our study, no aneurysms were found grossly or microscopically on histologic section. Avoidance of aneurysm formation is related to reduction of tension at the anastomotic site, care not to use excessive heat on vessel edges, and delivering the laser energy by a continuous mode. 17 Questions regarding whether or not conclusions based on studies in rat vessels are applicable to larger animals with thicker-walled vessels have been raised. Recent investigators have demonstrated the feasibility of CO2 laser-assisted anastomoses in domestic pigs with vessels much more similar to humans. 18 At the present time, enough encouraging work has been done to warrant continued investigation of this tool and possible application in the clinical setting.
