Effectiveness of coagulation factor XIII concentrate for reversing loss of tensile strength of rat intestinal anastomoses

BACKGROUND: Blood coagulation factor XIII (F-XIII) promotes cross-linking of fibrin during blood coagulation. Impaired clot stabilization in patients with genetic deficiencies of F-XIII is associated with marked pathologies of wound healing. METHODS: 60 rats given carbon tetrachloride underwent ileal anastomosis after which they received albumin (Alb animals) or F-XIII concentrate (F-XIII animals) immediately after surgery and daily thereafter until day 2 or 4 and were euthanized on day 3 or 5, respectively, or until day 5 and were euthanized on day 7, 10, or 21. We measured the plasma F-XIII activity and anastomotic tensile strength, followed by immunohistochemical localization of F-XIII subunit A within anastomoses. RESULTS: On day 3, there were no significant differences between Alb and F-XIII animals for plasma F-XIII activity and tensile strength, and both groups of animals showed little immunostaining for F-XIII on anastomoses. Plasma F-XIII activities did not differ between Alb and F-XIII animals on day 5 (115.8 +/- 16.8 vs. 137.3 +/- 14.9%). Although the tensile strength in both groups was increased compared with that of day 3, that in F-XIII animals (129.8 +/- 3.3 gf) was significantly higher than that in Alb animals (100.8 +/- 5.3 gf, p = 0.014). F-XIII animals showed de novo collagen fibers and intense immunoreactivity of F-XIII in the extracellular matrix around the anastomoses. Similar differences occurred on day 7 but not days 10 and 21. CONCLUSIONS: F-XIII concentrate may accelerate the early healing process of intestinal anastomosis because of the protein's accumulation in situ.     

Colonic anastomotic strength and matrix metalloproteinase activity in an experimental model of bacterial peritonitis

BACKGROUND: Clinical studies report conflicting results on the safety of primary intestinal anastomoses in the presence of peritonitis, and comprehensive experimental data are lacking. The present study investigated whether the strength of experimental colonic anastomoses is affected if surgery is performed in the presence of pre-existing bacterial peritonitis. METHODS: Colonic anastomoses were constructed in Wistar rats 24 h after caecal ligation and puncture or a sham procedure. Anastomotic strength was assessed by measuring breaking strength and bursting pressure during the first 5 days after operation. Anastomotic hydroxyproline levels were measured and matrix metalloproteinase (MMP) activity was analysed by quantitative gelatin zymography. RESULTS: Anastomotic strength was lowered in the presence of bacterial peritonitis but in a minor and transient way. The breaking strength was lower only immediately after construction of the anastomosis (- 15 per cent, P = 0.011) and the bursting pressure only on the third postoperative day (- 33 per cent, P = 0.038); no anastomotic dehiscence was observed. At 3 days after operation increased levels of MMP activity were observed but anastomotic hydroxyproline content was not affected by bacterial peritonitis. CONCLUSION: The influence of bacterial peritonitis on the development of anastomotic strength is limited. This experimental finding lends support to recent clinical studies that have demonstrated the feasibility of constructing a primary anastomosis under these conditions.     

Action of matrix metalloproteinases at restricted sites in colon anastomosis repair: an immunohistochemical and biochemical study

BACKGROUND: Dehiscence of colon anastomosis is a common, serious and potentially life-threatening complication after colorectal operation. In experimental models, impaired biomechanic strength of colon anastomoses is preventable by general inhibitors of matrix metalloproteinases (MMPs) and associated with collagen loss, which indicates a possible link between MMP-mediated collagen degradation and dehiscence. The precise localization of collagen degradation within the anastomotic area and the specific MMPs responsible are unknown. METHODS: We have analyzed distinct zones within anastomoses using a novel microdissection technique for collagen levels, collagenolytic activity exerted directly by endogenous proteinases, and MMP-8 and MMP-9 immunoreactivity and their collagenolytic activity. RESULTS: The most pronounced collagen loss was observed in the suture-holding zone, showing a 29% drop compared with adjacent micro-areas of 3-day-old anastomoses. Only this specific tissue compartment underwent a dramatic and significant increase in collagenolysis, amounting to a loss of 10% of existing collagen molecules in 24 hours, and was abolished by metalloproteinase inhibitors. The tissue surrounding suture channels was heavily infiltrated with CD68-positive histiocytes that expressed MMP-8 and to a lesser extent MMP-9. The collagenolytic effect of the interstitial collagenase MMP-8 was synergistically potentiated by the gelatinase MMP-9 when added to colon biopsies incubated in vitro. CONCLUSIONS: The unique finding of this study was that the specific tissue holding the sutures of a colon anastomosis lost the most collagen presumably through induction and activation of multiple MMPs that may explain the beneficial effects of treatment with non-selective MMP antagonists.     

Experimental study of singly placed staples for an everted intestinal anastomosis

This study was undertaken to confirm the technical feasibility and efficacy of an intestinal anastomosis created with singly placed staples in dogs. In 12 fully conditioned dogs, two end-to-end small bowel anastomoses were performed in an everted manner. In each dog, one anastomosis was performed with singly placed staples utilizing the Auto Suture 4.8 mm disposable skin stapler, and the other anastomosis was performed with a manual technique using 3-0 Dexon interrupted suture. Operation time was measured for each anastomosis. Dogs were sacrificed 2, 4, and 8 weeks postoperatively. Each anastomosis was examined grossly and microscopically, and its tensile strength was measured. All dogs survived without complications. Gross and microscopic examinations showed satisfactory healing of both types of anastomoses at different postoperative intervals. The stapled anastomosis required significantly shorter time (p less than 0.01), and had significantly greater tensile strength (p less than 0.05) when compared with manual anastomosis.     

Healing of ileocolic anastomoses. Breaking strength and collagen content in the intestinal wall after ileocolic resection and anastomosis in the rat

Breaking strength, collagen concentration and collagen content of the intestinal wall were studied in rats after ileocolic anastomosis. The values were compared with findings in control rats without operation and in previous studies of ileal and colonic anastomosis. Collagen content and concentration in the ileal wall were lower on the third day of healing than previously found during ileal healing. Breaking strength decreased in the early phase to the same extent as in previous experiments, but the restoration of strength from the third day on was more rapid than previously noted in ileal anastomoses. The changes observed in the ileum following ileocolic anastomosis were more like the pattern in colon. It is suggested that intestinal content (bacteria and intraluminal bulk) influences the collagen metabolism in the intestinal wall.     

Effect of the combination of fibrin glue and growth hormone on incomplete intestinal anastomoses in a rat model of intra-abdominal sepsis

BACKGROUND: The presence of established intra-abdominal sepsis has been considered a contraindication to primary anastomoses. Our hypothesis was that fibrin glue (FG), growth hormone (rhGH), and combination of them synergistically improve intestinal primary anastomotic healing in a rat model of intestinal fistulae with peritonitis. MATERIALS AND METHODS: Male Wistar rats, induced intestinal fistulae with peritonitis after 24 h, were performed an enterectomy and intestinal anastomoses. Group A, rats (n = 60) had a complete anastomoses (end-to-end single layer anastomoses using 12 inverted interrupted 6-0 sutures) without peritonitis, group B, rats (n = 60) had a complete anastomoses after 24 h of peritonitis, group C rats had an incomplete anastomoses (four inverted interrupted sutures), groups D, E, F rats (n = 60) received FG, rhGH, or both of them, respectively. rhGH was given daily for 5 days. Anastomoses indicated the anastomotic bursting pressure (ABP), tensile strength, and hydroxyproline content, were determined. RESULTS: On POD 1, ABP of group C and group D was significantly lower than that of other groups (P < 0.01); On POD 3, ABP could not be determined because of intestinal dehiscence in groups C and E, ABP was significantly higher in groups D and F than that of groups A and B (P < 0.01); the ABP increased after 5 days of operation in groups A, B, and F. At the same time, that of group D decreased (P < 0.01). On POD 5, the tensile strength was significantly higher in groups A, D, and F than that in groups C, and E. On POD 5, hydroxyproline content was higher in groups D and F compared to that in group C (P < 0.05). CONCLUSIONS: These data suggested that FG improve intestinal primary anastomotic healing within post-operative 5 days in a rat model of intestinal fistulae with peritonitis. RhGH alone fails to improve intestinal anastomotic healing, and the combination of FG and rhGH have no synergistic effect to improves intestinal anastomotic healing.     

Mechanism of tissue fusion in argon laser-welded vein-artery anastomoses

The mechanism of laser vascular tissue welding remains unknown. This study compared the acute tissue response and long-term healing of sutured and laser-welded anastomoses of vein segments used to bypass ligated canine femoral arteries. For each procedure, one anastomosis was formed using running 6-0 polypropylene suture (control), and the other anastomosis was formed using argon laser tissue welding (experimental). The vein grafts were harvested at 4 (n = 2), 8 (n = 1), 12 (n = 1), and 16 (n = 2) weeks, and selected samples were evaluated by histologic examination, electron microscopy, tensile strength testing, and by measuring the formation of [3H]hydroxyproline as an index of collagen synthesis. Examination of successful laser fusions immediately after they were formed showed bonding of collagen to collagen and elastin to collagen. Follow-up evaluations showed that the precision of tissue apposition affected the rate of healing and tensile strength. Laser-welded anastomoses demonstrated a progression of healing similar to sutured repairs, with remodeling of fibrous tissue and collagen being the primary component of weld integrity. This study demonstrates that sutured and argon laser-welded vein-artery anastomoses heal comparably up to 16 weeks postoperatively, and that laser welding is a satisfactory alternative to sutured anastomoses.     

Prophylaxis of insufficiency of gastrointestinal anastomoses

Experimental and clinical results of use of fibrin glue for strengthening "high risk" sutures of anastomoses in elective surgery of the esophagus, stomach and urgent abdominal surgery are presented. In experimental studies this glue permitted to increase mechanical strength and containment of anastomosis, to accelerate microbial elimination, activated reparative processes. In clinical practice fibrin glue permitted to avoid suture insufficiency of gastrointestinal anastomoses in the most unfavorable conditions (peritonitis, acute intestinal obstruction, oncological process, etc). It is concluded that fibrin glue is the high effective protective agent for gastrointestinal anastomoses.     

Effect of gentamicin-containing sponges on the healing of colonic anastomoses in a rat model of peritonitis.

OBJECTIVE: To study the influence of gentamicin-containing sponges on the healing of colonic anastomoses in a rat model of peritonitis. DESIGN: Controlled laboratory study. SETTING: University hospital, Belgium. MATERIALS: 40 male Wistar rats. INTERVENTIONS: Peritonitis was caused by implantation of a gelatin capsule containing faeces and barium sulphate. The rats then had a colonic anastomosis. They were divided into 4 groups (n = 10 in each). The control group (no additional treatment); a second group in which a plain collagen sponge was wrapped around the anastomosis; a third group in which a gentamicin-containing collagen sponge was wrapped around the anastomosis; the last group in which the animals were given an intramuscular dose of gentamicin. MAIN OUTCOME MEASURES: Operative mortality, weight loss and anastomotic bursting pressure four days after the anastomosis. RESULTS: Seven rats died before necropsy but none in the last group. Peritonitis developed in all rats Weight loss was significantly higher in the plain collagen group. Bursting pressures were similar in the control and two gentamicin groups. In the plain collagen group all the anastomoses but one had broken down. CONCLUSION: There was no difference in bursting pressure between rats treated with gentamicin sponges or systemically, and controls. Healing was severely compromised when a plain collagen sponge was used.     

Sealing of Gastrointestinal Anastomoses with a Fibrin Glue-Coated Collagen Patch: A Safety Study

Sealing of anastomoses has previously been tested with several methods, including sealing with liquid fibrin glue. Sealing with a collagen patch coated with fibrin glue components has never been systematically examined. The aim of the present study was to determine the safety of sealing gastrointestinal anastomoses with a collagen patch coated with fibrin glue. The study is a prospective, experimental animal study comparing sealed and unsealed gastrointestinal anastomoses. Laparotomy was performed in 11 pigs under general anesthesia. In each pig two anastomoses were performed on the small intestine. One of the anastomoses was sealed with a collagen patch coated with fibrin glue components (TachoSil®). The other anastomosis contained no sealing. The pigs were observed for 1 to 6 weeks. The observation period was followed by in vivo examination under general anesthesia and included observation for anastomotic leakage, signs of present or former peritonitis, abscess, adhesions to the anastomoses, and signs of intestinal obstruction. In addition, the anastomotic diameter was measured with barium and radiography. Finally, bursting pressure was measured in each segment. After the pigs were sacrificed, the bowel segments were microscopically examined. There were no differences between the sealed and the unsealed anastomoses with respect to abdominal pathology, in vivo bursting pressure, or degree of stenosis. The collagen fleeces were in situ in all anastomoses. Microscopically, we found no difference in healing or signs of infection.     

Effect of the Combination of Fibrin Glue and Growth Hormone on Intestinal Anastomoses in a Pig Model of Traumatic Shock Associated with Peritonitis

Background  Intra-abdominal sepsis and hemorrhagic shock have been found to impair the healing of intestinal anastomoses. The present study examined whether fibrin glue (FG) and recombinant human growth hormone (GH) can improve intestinal primary anastomotic healing in a pig model of traumatic shock associated with peritonitis. Further, the study was designed to investigate the probable mechanism of these agents. Methods  Female anesthetized pigs were divided into five groups. Group sham (n = 7), pigs without traumatic shock had small bowel resection anastomoses; group control (n = 14), pigs had bowel resection anastomoses 24 h after abdominal gunshot plus exsanguination/resuscitation; group FG (n = 14); group GH (n = 14); group FG/GH (n = 14), pigs received FG, recombinant GH, or both, respectively. Recombinant GH was given daily for 7 days. Blood samples were collected daily for measurement of interleukin-6 (IL-6) and tumor necrosis factor (TNF)-α levels. Investigations also included adhesion formation, anastomotic bursting pressure, tensile strength, hydroxyproline (HP) content, myeloperoxidase (MPO), tumor necrosis factor (NF)-κB activity, and histology analysis 10 days later. A second experiment (n = 20 subjects assigned to each of the five groups) was designed to study survival during the first 20 postoperative days. Results  Traumatic shock associated with peritonitis led to significant decreases in intestinal anastomotic bursting pressures, tensile strengths, and tissue hydroxyproline content, along with severe adhesion formation, increases in MPO activity and NF-κB activity, and plasma levels of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Both FG and recombinant GH treatment led to early significant increases in plasma levels of TNF-α and IL-6. At the same time, FG alone, unlike recombinant GH alone, led to significant increases in anastomotic bursting pressures, tensile strength, and tissue HP content, along with decreases in anastomotic MPO and NF-κB activity and later plasma levels of TNF-a and IL-6. The FG group also developed more marked neoangiogenesis and collagen deposition on histology analysis. However, FG and recombinant GH synergistically effected improved anastomotic healing, abolishing the infaust effects promoted by recombinant GH. Adhesion formation after intestinal anastomosis could not be lowered by FG alone or by the combination of FG and recombinant GH. Both FG alone and FG/GH, in contrast to GH alone and control treatment, significantly prolonged the survival time of experimental animals. Conclusions  We found that FG, but not recombinant GH, could lower the risk of anastomotic leakage, improve intestinal anastomotic healing, and prolong survival in a pig model of traumatic shock associated with peritonitis. Both FG and recombinant GH synergistically effected improved intestinal anastomotic healing. It was suggested that GH could be used locally to promote intestinal anastomotic healing in intra–abdominal peritonitis.     

Burst strength testing of porcine intestinal anastomoses following negative pressure therapy

The effect of negative pressure therapy (NPT; The ABThera? Open Abdomen Negative Pressure Therapy System, KCI USA, Inc., San Antonio, TX) on the integrity of small intestinal anastomoses was evaluated using in situ burst strength testing in a domestic pig model. In each of 3 swine, 8 anastomoses were created, 4 using sutures and 4 using staples. After 24 hours of continuous NPT, each anastomosis was subjected to burst strength testing in situ. Mean ratios of burst strength of sutured anastomoses to baseline intraluminal pressure were 9.0 to 10.9. Stapled anastomoses had significantly lower burst strength than sutured anastomoses, but mean values were still at least 4.6 times greater than baseline. No differences were seen between anastomoses that were located in close proximity with treatment and those remotely placed or when measured with negative pressure on or off at burst assessment. NPT had no acute adverse effect on intestinal anastomoses in swine.     

Enabling sutureless vascular bypass grafting with the exovascular sleeve anastomosis

PURPOSE: We describe a technique for end-to-end sleeve anastomosis that may enable minimally invasive bypass grafting and characterize the tensile strength, stenosis rate, durability, and healing of the anastomosis. METHOD: An anastomotic device assembly consisting of a cable tie-type band with mobile teeth elements is mounted on the outer surface of a polytetrafluoroethylene graft. The graft is drawn over the artery resulting in a sleeve of vessel within the graft. As the band is tightened over an intraluminal obturator, the independently mobile anchoring teeth are driven through the graft into the artery. The tensile strength of the anastomosis was compared with sutured anastomosis during in vitro studies using cadaveric human femoral arteries. For in vivo studies on pigs and goats, we used a proximal exovascular sleeve anastomosis along with a distal sutured aortic anastomosis. Survival animals were studied by angiogram postoperatively and at the time of explantation. RESULTS: In vitro studies showed no difference in maximal tensile strength between sutured and exovascular anastomoses (10.5 +/- 2.7 lb vs 10.2 +/- 3.0 lb, P =.83). However, loss of continuous graft to artery interface occurred at lower loads in the sutured anastomoses (6.5 +/- 0.6 lb, P <.05). In total, all 24 pigs tested in nonsurvival or survival settings sustained a successful and leakproof anastomosis. Of the 13 nonsurvival cases, maximal epinephrine-induced hypertension sustained over 15 minutes (peak systolic blood pressure > 210-250 mm Hg) was tolerated without leakage in a subgroup of five animals (100%). All 11 survival pigs had no pseudoaneurysms or stenosis relative to sutured control anastomoses at 6 week explantation (8.2 +/- 1.25 mm vs 8.5 +/- 1.6 mm, P =.21). The three long-term survival goats had no pseudoaneurysm or stenosis after 40 weeks. Histologic examination confirmed healing of the aorta to graft with minimal neointimal hyperplasia. CONCLUSION: Exovascular sutureless anastomosis appears comparable to sutured anastomosis in stenosis rate, healing, and durability, with some advantages in tensile strength and rapidity of application.     

Comparative experimental study of left colonic anastomoses in intestinal obstruction; the value of anastomoses protection with free peritoneal graft

The paper describes the concept of peritoneal graft used to reinforce the colo-colic anastomoses made in emergency conditions of left colic obstruction, experimentally induced by surgical ligature, on Wistar rats. The comparative study was done on 24 rats, divided in 3 groups: group A with colic anastomoses protected with peritoneal graft, group B with one-layer colic anastomoses and group C with two-layer colic anastomoses. After 8 days, 7 rats survived in group A, 2 rats in group B and 3 rats in group C. All surviving rats in groups B and C presented anastomotic leak with local peritonitis, while in group A the anastomosis were healed. For group A, bursting strength of the anastomosis was measured and the mean value found was 63.64 cmH2O. It was proved the importance of protecting the colic anastomosis with supplementary layers, which increase the mechanical resistance and also prevents minor spillage of the colic content during the first postoperative days.     

Effects of prophylactic antibiotics on colonic healing.

The effect of antibiotic colon preparation on the tensile strength and morphologic appearance of colonic anastomoses has been investigated in dogs. Preparation with preoperative kanamycin did offer a slight benefit over mechanical bowel cleansing. The addition of erythromycin and kanamycin to the preoperative bowel preparation significantly (p less than 0.001) improved the mean tensile strengh of the healing colonic anastomosis. Continuation of erythromycin and kanamycin for one week postoperatively almost doubled the mean tensile strength of the healing anastomosis. Continuation of erythromycin without kanamycin in the postoperative period provided little protection over the preoperative administration of kanamycin and erythromycin. Histologic examination showed that erythromycin and kanamycin given during the pre- and postoperative period changed the mode of healing from that of secondary intention to healing by first intention. The findings support the concept that soilage of the peritoneal cavity at the time of elective colon surgery is not as important as leakage caused by poor anastomotic healing. Antibiotic bowel preparation with kanamycin and erythromycin improves the healing of colonic anastomoses.     

Anastomoses of the small intestine in a septic environment protected by polyglactin 910-collagen mesh. Experimental study in rats

An experimental study was carried out in rats to evaluate the outcome of small bowel anastomoses in the presence of peritonitis with and without protection by a polyglactin 910 mesh. One hundred and thirty rats were operated. 1) Thirty small bowel anastomoses were performed in a sterile environment to evaluate the morbidity and mortality due to the surgical procedure itself. All these animals had an uneventful course. 2) Forty anastomoses were performed in a septic environment without protection. Twelve rats died immediately after the procedure. Six rats developed an anastomotic fistula and 22 had an uneventful course. 3) Sixty anastomoses were performed in a septic environment and protected by a polyglactin 910 mesh. Seventeen rats died immediately after the procedure. There were no anastomotic disruptions. Seventeen rats had an uneventful course, and 28 (65%) developed stenosis of the anastomosis. Protection of small bowel anastomoses by a polyglactin 910 mesh appears to effectively prevent disruptions (no anastomotic fistulae or locoregional infections were recorded). However, the mesh is responsible for an intense inflammatory reaction, that often results in intestinal obstruction.     

Healing process of laser–welded intestinal anastomosis

Intestinal welding by means of low-power laser has been reported as an efficient method for intestinal anastomosis. We designed an experimental model in rats to investigate collagen and DNA concentrations in CO₂ laser–welded anastomoses as compared with those in sutured anastomoses on the 4th, 7th, and 10th postoperative days. The results revealed that DNA, total collagen, and insoluble collagen concentrations were significantly lower in the lased anastomoses than in the sutured anastomoses on the 4th postanastomotic day. On the 7th and 10th postanasto-motic days, collagen concentrations increased in the laser-treated group attaining significantly higher levels than in the sutured group at that time. These findings are compatible with other studies demostrating that laser–welded intestinal anastomoses are more prone to dehiscence during the first 4 postanastomotic days, but become at least as effective as the sutured ones with passage of time. © 1994 Wiley-Liss, Inc.     

Piroxicam affects collagen changes around experimental intestinal anastomoses

The effects of piroxicam on postoperative changes of collagen--measured as hydroxyproline--concentrations were measured around intestinal anastomoses in rats. Piroxicam, in a dose of 2 mg/kg/day, significantly reduced the decrease of hydroxyproline concentrations around colonic anastomoses during the first 3 days after the operation but also reduced the increase of hydroxyproline concentrations observed at day 7 around ileal anastomoses in the control group. 10 mg piroxicam/kg/day resulted in a 100% lethal peritonitis after the 5th postoperative day. We suggest that piroxicam affects collagen metabolism by inhibiting granulocyte functions.     

Comparison of tensile strength and thrombus formation between mechanical microvascular anastomoses using a biodegradable ring device and sutured anastomoses

The purpose of this study was to evaluate whether early motion following mechanical anastomosis using a biodegradable ring device was possible or not, by measuring tensile strength and the rates of thrombus formation at anastomotic sites. Bilateral femoral arteries and veins of 24 rabbits were repaired by sutured anastomoses and biodegradable ring anastomoses. The tensile strength of the anastomotic site was measured by constant loading with a material-testing machine, using specimens excised at 24 hr, 72 hr, 1 week, and 2 weeks after anastomosis. The tensile strength of biodegradable ring arterial anastomoses was significantly stronger than sutured anastomoses at 24 hr, 72 hr, 1 week, and 2 weeks. No statistically significant differences were observed in venous anastomoses at any interval. In separate experiments, biodegradable ring anastomoses and sutured anastomoses of the bilateral femoral arteries of 18 rabbits were constructed, and early passive knee motion was carried out at 100 times once a day with maximum spreading of the hip joint for 24 hr, 72 hr, and 1 week. Thrombus formation at the anastomotic sites was evaluated by scanning electron microscope (SEM). SEM showed no thrombus formation in the biodegradable ring anastomoses at any interval; however, thrombi were observed in the sutured anastomoses (33 to approximately 50 percent).     

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.