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.     

Creating the Uncreatable

ABSTRACT

Introduction: Metoclopramide is often used in the treatment of postoperative nausea and vomiting, but a literature review failed to find reports on the influence of this drug on the healing of bowel anastomoses in the setting of abdominal sepsis. The aim of this study was to evaluate the effects of metoclopramide on the healing of left colonic anastomoses in rats with induced abdominal sepsis. Materials and Methods: Forty rats were divided into two groups of 20 animals each to receive either metoclopramide (experimental group: E) or saline (control group: C). Each group was further divided into subgroups of 10 animals each to be killed on the third (E3 and C3) or seventh postoperative day (E7 and C7). A segmental resection of the left colon was performed, followed by end-to-end anastomosis. Sepsis was induced by cecal ligation and puncture. On the day of reoperation, the total number of adhesions was assessed and the anastomosed bowel segment was removed for tensile strength testing, histopathological analysis, measurement of hydroxyproline levels, and histomorphometric evaluation of collagen. Results: Intraoperative findings, number of intra-abdominal adhesions in the anastomosed area, and tensile strength before anastomosis rupture were similar among all subgroups at all assessments. On the third postoperative day, the anastomoses of animals treated with metoclopramide showed significantly lower hydroxyproline levels (p = 0.01) when compared with controls. Collagen content was similar among all subgroups. Conclusions: Metoclopramide does not have deleterious effects on the healing of bowel anastomoses in rats subjected to experimental abdominal sepsis.     

Recombinant growth hormone's effects on the strength and thickness of radiation-injured ileal anastomoses: a rat model.

BACKGROUND: Small bowel resections following radiotherapy for gynecologic cancers have resulted in significant rates of morbidity and mortality. The objective of this study was to evaluate the effect of rGH on the breaking strength and thickness of radiation-injured ileal anastomoses in an animal model. MATERIALS AND METHODS: Sprague-Dawley rats were treated with 1800 cGy of pelvic irradiation in a single fractionation. Seventeen weeks following pelvic teletherapy an ileo-ileostomy was performed. The rats were randomized to receive 2.0 mg/kg/day of rGH for 7 days or placebo. On the seventh postoperative day a segment of ileum surrounding the anastomosis was resected. The segments were tested for breaking strength or were histologically measured for anastomotic thickness. RESULTS: The ileal anastomotic breaking strength in the rGH group was 181 +/- 8.4 g (mean +/- standard error). The breaking strength of ileal anastomoses in the placebo group was 133 +/- 6.9 g (P < 0.05). The rGH group demonstrated a greater anastomotic thickness (1.65 +/- 0.116 mm) than the placebo group (1.17 +/- 0.113 mm, P < 0.05). Of placebo rats 14.7% developed anastomotic leaks compared to 0% of rGH-treated animals (P < 0.05). CONCLUSIONS: RGH increased the ileal anastomotic breaking strength by 36% in radiated rats. The anastomotic leak rate was reduced from 14.7% in the placebo group to 0% in the rGH group. These findings correlated with a 41% increase in the thickness of the anastomotic connective tissue in the rGH group. Clinical investigation in selected patients is warranted.     

三种不同胰肠吻合术可靠性比较的实验研究

目的观察3种不同胰肠吻合术的愈合过程,比较其吻合口的可靠性。方法按吻合术式的不同,将54只实验家猪分为3组：套入式胰肠端端吻合组(套入组)、捆绑式胰肠吻合组(捆绑组)和“墨池”式胰肠吻合组(“墨池”组),分别于术中、术后5 d、术后10 d测定吻合口爆破压和离断力,吻合口周围组织做病理检查。结果(1)爆破压：套入组术中、术后5 d、术后10 d分别为(67±8)、(96±11)、(131±9)mm Hg(1 mm Hg=0．133 kPa);捆绑组分别为(140±8)、(179±10)、(269±13)mm Hg;“墨池”组分别为(102±10)、(171±18)、(254±24)mm Hg。捆绑组和“墨池”组较套人组在术中及术后5、10 d的爆破压均有明显增加(P<0．01);捆绑组较“墨池”组术中爆破压高(P<0．05),但在术后5、10 d捆绑组爆破压与“墨池”组比较差异无统计学意义。(2)离断力：套入组术中及术后5、10 d分别为(4．6±0．6)、(5．8±0．5)、(7．1±0．6)N;捆绑组分别为(4．5±0．4)、(6．6±0．4)、(10．0±0．6)N;“墨池”组分别为(4．6±0．3)、(6．5±0．4)、(9．1±0．9)N;3组两两比较术中离断力基本相同;术后5、10 d时捆绑组和“墨池”组基本相同,均明显高于套入组(P<0．01)。(3)组织病理学：捆绑、“墨池”组在术后10 d时吻合口均已基本由结缔组织修复,胰腺残端断面已基本由黏膜上皮覆盖。而套入组则由肉芽组织不完全修复,胰腺残端断面尚无上皮再生。结论捆绑式胰肠吻合口愈合强度高、速度快。“墨池”式胰肠吻合口愈合速度也较快,但抗离断力方面不如捆绑式。套入式吻合口可靠性在3种胰肠吻合术式中最差,具有较大的胰漏风险。     

The influence of the rapamycin-derivate SDZ RAD on the healing of airway anastomoses.

OBJECTIVE: Among the many immunosuppressive effects of SDZ RAD (40-0(2-hydroxyethyl)-rapamycin), a rapamycin derivative, is the inhibition of fibroblast proliferation. Since the long-term success of lung transplantation is limited by the development of bronchiolitis obliterans, a fibroblast-associated progressive luminal obstruction of the terminal bronchioli, the use of SDZ RAD as immunosuppressive in pulmonary graft recipients may counteract this process. However, reduction of fibroblast activity, posttransplant, may impair the healing of the bronchial anastomoses. MATERIALS AND METHODS: The cervical trachea in pigs was denuded, divided and re-anastomosed with Prolene 4-0 single stitches. Control animals (group 1, n=4) were without, and study animals (group 2, n=6) were with SDZ RAD therapy (1.25 mg/kg/day, p.o., 14 days). After 14 days, the pigs were sacrificed. The anastomoses were examined histologically, and breaking strength of tracheal strips of 5-mm width was measured. RESULTS: All animals survived without complications. Serum levels of SDZ RAD were 30.9+/-8.7 ng/ml (recommended level 20-40 ng/ml). All anastomoses healed macroscopically without difference between the two groups. Breaking strength was significantly lower in the treated animals (group 1 vs. group 2: 11.75+/-0.35 vs. 7.69+/-1.39 N, P=0.01). Histology did not show a significant change in histoarchitecture between the groups. CONCLUSIONS: Although SDZ RAD significantly reduced the breaking strength of the tracheal anastomosis, no obvious histological differences between treated and untreated animals could be detected. Since this model does not reflect the clinical situation, further investigations are necessary to reveal the effect of SDZ RAD on airway wound healing in concert with a contemporary clinically used multidrug immunosuppressive regimen in allograft recipients.     

A comparison of interrupted and continuous sutures for tracheal anastomoses in sheep.

OBJECTIVE: To study the tensile strength of tracheal anastomoses. DESIGN: Experimental study. SETTING: University medical school laboratory, Germany. ANIMALS: 15 sheep. INTERVENTIONS: Tracheal anastomoses with three different suturing techniques: a continuous suture and interrupted sutures with either a monofilament or a polyfilament material. Anastomoses were tested to breaking after being in place for 1, 2, 4, 8 or 24 weeks. RESULTS: After one week, with all three materials, the trachea broke at the anastomosis. In animals that survived longer, the trachea broke further away from the anastomosis. There was no significant difference between the mean values of the breaking force for continuous sutures and single interrupted sutures (p = 0.9). CONCLUSION: The suturing technique (continuous or interrupted) has less relevance for the tensile strength of the anastomosis than in vitro experiments suggest.     

Stapled aortic anastomoses: a minimally invasive, feasible alternative to videoscopic aortic suturing?

Widespread applications of totally laparoscopic aortic reconstructions have been limited by the long cross-clamp time required to suture the aortic anastomosis despite improvement in instrumentation. The authors' hypothesis was that a "one-step anastomosis concept" using an intraluminal stapler would allow shorter cross-clamp time but similar patency and imperviousness as videoscopic suturing techniques. An intraluminal stapler (Endopath-ILS, Ethicon) with a modified anvil was used to perform videoscopic-assisted thoracic aorta-to-iliac artery bypass with a 21 mm by 8 mm polytetrafluoroethylene (PTFE) graft in 22 sheep through a minimally invasive approach using a 5 cm thoracotomy. The graft-to-iliac artery anastomoses were hand sutured through a flank incision. Twelve sheep were used to establish the technique and 10 subsequent animals constituted the study group. Aortic cross-clamp time, imperviousness, and need for additional sutures were recorded and compared to previously reported data using videoscopic suturing in pigs. Patency was assessed by comparing lower limb arterial pressures. Macroscopic and microscopic examinations of the anastomoses were performed at different time-points within the first 3 months. Videoscopic-assisted stapled anastomoses were also performed on atherosclerotic aortas of 3 human cadavers. Stapled anastomoses between the thoracic aorta and PTFE graft were completed in 8 of 10 animals. Two animals were euthanized after stapler failure and anastomotic bleeding. Sutures to strengthen the anastomosis had to be used in 4 cases. Mean aortic cross-clamp time in 8 successful cases was 4.3 +/-2.9 minutes (range 2-11 minutes) and was significantly shorter than clamp time of videoscopic suturing technique (48.7 +/-9.4 minutes, p < 0.0001). Imperviousness was good or excellent in 4 animals and fair in 4 animals. All anastomoses were patent at the end of the procedure. Examination of the anastomosis of the 2 failed interventions showed medial aortic tear surrounding the anastomosis in 1 case and misfired staples in the other. No graft occlusion was noted during follow-up ranging from 0 to 12 weeks. At the time of harvest, no bleeding was noted after epinephrine and volume infusion to increase mean arterial pressure to 200 mm Hg for 15 minutes. Macroscopic examination of the anastomoses revealed adequate healing with circumferential stapling of the prosthesis to the aortic wall and no stenosis or thrombus except in 1 false aneurysm (1/7, 14%). Surface electron microscopy showed cells coverage of the anastomosis surface. When applied on human cadaver thoracic and abdominal aorta with atherosclerotic changes, clamping times of less than 5 minutes were achieved. However, imperviousness tested with saline was poor. An automatic stapling device allows performance of a graft-to-aorta anastomosis through a minimally invasive approach with shorter clamping time than a videoscopic suturing technique. However, the current technique of aortic stapling is unreliable and further improvements are needed.     

Fibrin glue protection of primary anastomosis in the obstructed left colon. An experimental study on the rat

A left-sided colon obstruction was produced with a polypropylene sling in 65 rats. Colon resection and primary anastomosis were performed three days later. The animals were then randomly allocated to the FG (fibrin glue) group receiving sealing of the anastomosis with 0.4 ml of fibrin glue (Beriplast R), or to the NG (non-glue) group. The anastomoses were assessed 30 min, two days and four days later. Adhesion formation was similar in both groups. The number of macroscopic or radiological leakages did not differ either. At 30 min the mean bursting pressure was 74.6 +/- 8.6 (SD) mmHg in the FG group and 58.3 +/- 21.6 mmHg in NG (non-glue) group (p less than 0.05, Mann-Whitney test). Later on the strength of the anastomoses was equal in both groups. We conclude that the initial sealing of weak points in the anastomoses was beneficial but the inherent strength per se could not be enhanced.     

Effect of intravenous aprotinin (Trasylol) on the healing of experimental colonic anastomoses in the rabbit

A randomized controlled trial to assess the effect of intravenously administered Trasylol on the healing of experimental colonic anastomoses in the rabbit has been performed. Before undergoing a standard left colonic resection and anastomosis, the animals received intravenous Trasylol (80,000 KIU). Postoperatively 160,000 KIU were given in divided doses per day for 3 days. Control animals received saline placebo. The mean bursting pressure of the anastomoses in the Trasylol-treated group was 47.7 +/- 3.0 mm Hg compared with 37.5 +/- 3.3 mm Hg for the control group (p less than 0.05). The mean difference in collagen content of the anastomosis compared to the resected specimen was +1.25 +/- 0.50 micrograms/mg and -1.02 +/- 0.47 microgram/mg for Trasylol and placebo, respectively (p less than 0.005). In this model intravenous Trasylol produces a significant elevation of the bursting pressure and a significant improvement in the collagen content of the anastomosis. This may be the result of collagenase inhibition.     

Reinforced graft-to-artery anastomosis: an experimental study

This experiment was designed to study the effects of reinforcing graft-to-artery anastomoses. A section of infrarenal aorta was replaced with a Dacron graft in 24 dogs. In eighteen animals one anastomosis was reinforced with a cuff of Dacron graft material, while the remaining six dogs both anastomoses were reinforced, one with graft material and the other with Dacron mesh. The animals were sacrificed at three week to six month intervals. The grafts were examined grossly and microscopically, and the tensile strength of the anastomosis determined. There was no difference in tensile strength or in the luminal healing. There was only limited fibrous healing under the graft material cuff whereas there was full incorporation of the mesh cuff. Conclusions: Reinforcement is not required routinely. When used, the cuff should be made with mesh rather than graft material.     

Effects of a static magnetic field on wound healing: results in experimental rat colon anastomoses

BACKGROUND: Research has shown that pulsed electromagnetic fields (EMFs) promote wound healing in experimental colonic anastomosis; however, the effects of static EMFs in this setting have not been investigated to date. METHODS: Fifty male Wistar rats were used. Ten served as controls for mechanical strength testing, and the other 40 underwent descending colon resection and anastomosis. Twenty of these 40 animals (M group) had NeFeB magnets placed in contact with the anastomosis site (magnetic field strength at the site 390 to 420 G). The other 20 animals (sham [S] group) had non-magnetized NeFeB bars of the same dimensions and weight implanted. Half of the animals in each group were killed and assessed for healing parameters on postoperative day 3 (M3 and S3 groups) and the other half on postoperative day 7 (M7 and S7 groups). Four types of assessment were done: gross healing, mechanical strength, hydroxyproline deposition, and histopathology. RESULTS: There were no differences between the M and S animals with respect to gross healing parameters. The mechanical strength was also not different between groups (23.8 +/- 12.7 and 24.7 +/- 9.6 mm Hg for M3 and S3, respectively; P = .863 and 91.3 +/- 65.4 and 94.8 +/- 55.9 mm Hg for M7 and S7, respectively; P = .902). Similarly, hydroxyproline deposition was not different between groups on postoperative day 3 or day 7. On postoperative day 3, the M group had significantly higher scores than the S group for fibroblast infiltration (2.4 +/- 0.7 vs 1.4 +/- 0.7, respectively; P = .008) and capillary formation (2.5 +/- 0.7 vs 0.9 +/- 0.4, respectively; P <.001). However, these effects were reversed and did not endure by day 7. CONCLUSIONS: The study results suggest that static EMF has no effect on experimental colonic wound healing in the rat.     

二种胰肠吻合术吻合口创伤愈合的实验研究

目的　观察比较两种胰肠吻合方法创伤愈合过程。　方法　按吻合方法不同将动物分为捆绑式胰肠吻合组 (Ⅰ组 )和套入式胰肠端端吻合组 (Ⅱ组 ) ,分别在术中、术后 5、10d活体测定吻合口破裂压和离断力 ,并做病理观察。　结果　 (1)破裂压 :Ⅰ组 ,0、5、10d分别为 (139 7± 8 0 )mmHg、(178 7± 9 7)mmHg和 (2 6 8 8± 12 8)mmHg ,Ⅱ组则为 (6 7 3± 7 9)mmHg、(96 2± 10 4 )mmHg和 (130 6± 9 3)mmHg。Ⅰ组和Ⅱ组在 0至 5d和 5至 10d两时间段分别增加 2 7 9%、5 0 5 %和 4 2 9%、35 7% ,两组间在 0、5、10d时差异具有非常显著性 (P <0 0 1)。 (2 )离断力 :Ⅰ组 ,0、5、10d分别为 (4 5± 0 4 )N、(6 6± 0 4 )N和 (10 0± 0 6 )N ;Ⅱ组为 (4 6± 0 6 )N、(5 8± 0 5 )和 (7 1± 0 6 )N。两组在 0天时基本相同 ,但Ⅰ组在 0至 5d和 5至 10d两时间段有较快增长(44 8%和 5 2 9% ) ,两组间在 5、10d时差异具有显著和非常显著性 (P <0 0 5和P <0 0 1)。 (3)组织病理学 :Ⅰ组在 10d时吻合口已由结缔组织基本修复 ,胰腺残端断面已基本由黏膜上皮覆盖。而Ⅱ组则由肉芽组织不完全修复 ,胰腺残端断面尚无上皮再生。　结论　捆绑组 (Ⅰ组 )吻合口强度更强 ,愈合更快。     

Development of an animal model for assessment of the hemostatic efficacy of fibrin sealant in vascular surgery

PURPOSE: Sustained hemostatic function of fibrin sealant (FS) is crucial when it is used in cardiovascular surgery. The purpose of this study was to develop a model that can determine the long-term hemostatic efficacy of tissue sealants in a vascular surgery. METHODS: To determine the ability of the model to detect differences in FS performance, various concentrations of FS were prepared and tested. Tensile strength of FS clots was determined in vitro using a tensiometer. Laparotomy was performed on 49 anesthetized rabbits, and a segment of the aorta was occluded, transected, and then sutured in an end-to-end fashion with four or eight interrupted 9-O sutures. The four-suture repair was covered with FS or placebo, and blood flow restored. Spilled blood was absorbed with gauze and weighed to estimate blood loss. Four weeks after surgery the animals were euthanized and the vessels recovered for histology. RESULTS: Average tensile strength of FS clots at 120, 90, and 60 mg/ml topical fibrinogen complex (TFC) concentration was 0.42 +/- 0.07 N, with no significant difference among them. The lowest TFC concentration, 30 mg/ml, produced weaker clots than either 120 or 90 mg/ml (P < 0.05). All rabbits with four-suture anastomoses that were treated with placebo bled to death after the vessel was unclamped (n = 6). Treatment of suture line with standard FS concentration (120 mg/ml TFC, n = 8) sealed the anastomosis and prevented blood loss. Hemostasis was sustained for 4 weeks, allowing vascular healing. All rabbits with the eight-suture anastomosis survived the operation but lost 42 +/- 9.2 ml blood (n = 5). Hemostatic efficacy of FS was unchanged when TFC was diluted to 90 mg/ml (n = 6) but further dilution to 60 mg/ml with water (n = 8) produced significantly less effective clots, with an average blood loss of 5.5 +/- 7.6 ml (P < 0.05) and two fatal clot failures postoperatively. When FS was diluted to 60 mg/ml TFC with a buffer, it maintained its hemostatic strength (n = 6). Further TFC dilution to 30 mg/ml led to consistent bleeding with an average blood loss of 35.3 +/- 10.3 ml (P < 0.001, n = 6). CONCLUSIONS: The four-suture anastomosis of rabbit aorta offers a consistent and reliable method for evaluating the short- and long-term hemostatic efficacy of FS products. This model is not only able to determine the functional differences in various concentrations of FS, but it is also sensitive to detect the subtle changes in FS preparation (e.g., medium composition) that is not detected by in vitro testing.     

Experimental study of a new vascular anastomotic technique in a swine model: short and mid-term results

This study reports the development of a new open external vascular stent: the lock stent device (LSD). It enables a novel end-to-end sleeve anastomotic technique, named locked anastomosis (LA). The LA technique consists of inserting a graft sleeve within an artery, secured in place by an internal stent and an external LSD. The internal stent, graft, vessel wall, and LSD are fastened together with single sutures. The LSD placement does not require a complete transection of the vessel wall as it can be enlarged and then relaxed to clasp the vessel neck. The tensile strength of the LA technique was accurately measured ex vivo and its stability successfully tested in vivo by acute pressure peak tests and mid-term survival studies. Ex vivo, the ratio between the tensile strength of the LA technique with two, three, and six stitches and that of hand-sewn anastomoses was 0.41 +/- 0.02, 0.59 +/- 0.17, and 1.03 +/- 0.04. In vivo, LA anastomoses tolerated marked increases in blood pressure (peak systolic pressure 195-230 mm Hg) for periods of 15-25 min without leakage. Five pigs survived 10 weeks with abdominal aorto-aortic bypass performed according to the LA technique with three stitches. Aortograms showed no narrowing or thromboses, and histological findings confirm uniform flattening of the aortic wall at the anastomosis, with proliferating neointima and uniformly hypotrophic media. Minimal changes were observed in the adventitia.     

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).     

Protease inhibitor reduces loss of tensile strength in rat anastomosis with peritonitis

BACKGROUND: The tensile strength in intestinal anastomoses decreases postoperatively in association with degradation of the extracellular matrix, and these changes would be expected to be more intense in the presence of peritonitis. MATERIALS AND METHODS: In this study, we investigated extracellular matrix degradation and tensile strength in a rat model of intestinal anastomosis with peritonitis. In the chemical peritonitis model, peritonitis was induced 24 h earlier with intraperitoneal HCl. A serine protease inhibitor, nafamostat mesilate (NM), was given intraperitoneally to some animals every 12 h from immediately after the operation for 3 days. Immunostaining was performed by the standard streptavidin-biotin-peroxidase method after fibronectin (Fn) and factor XIII antigen retrieval on paraformaldehyde-fixed, paraffin-embedded tissue sections. RESULTS: In comparison with controls, administration of NM reduced the loss of tensile strength on Day 3 in a dose-dependent manner, and high-dose NM (20/mg/kg) significantly prevented the loss of tensile strength on Day 3 (P < 0. 05). In the control group, degradation of the collagen layer in the anastomosis was associated with disappearance of Fn and factor XIII staining on Day 3. The administration of NM attenuated these changes with intense immunostaining for Fn and factor XIII seen particularly between collagen fibers on both sides of the anastomosis on Day 3. In the chemical peritonitis model, administration of NM also significantly prevented the loss of tensile strength on Day 3 without disappearance of collagen fibers. CONCLUSION: These findings suggest that NM may be clinically useful for preventing intestinal leakage, particularly when anastomoses are performed under protease-activating conditions, such as intestinal edema and inflammation.     

Is the GraftConnector a valid alternative to running suture in end-to-side coronary arteries anastomoses?

BACKGROUND: An animal study was carried out to compare long-term patency rates of coronary anastomoses performed with the GraftConnector versus running suture technique. METHODS: 10 sheep, 45 to 55 kg, underwent off-pump coronary artery bypass grafting (right internal mammary artery to left anterior descending artery). In 5 animals, the anastomosis was performed with a GraftConnector and in 5 animals with 7-0 running suture. Intraoperative fluoroscopy and a fluoroscopic control at 6 months were performed. After 6 months, the animals were sacrificed and the anastomoses were examined histologically. RESULTS: All animals survived at 6 months with 100% anastomosis patency rates in both groups. In the GraftConnector group, the anastomosis diameter at 6 months fluoroscopy was 118% of native left anterior descending artery versus 97% of the control group. Luminal anastomotic width at histology was 1.7 +/- 0.2 mm in the device group versus 1.6 +/- 0.1 mm in the control group. Mean intimal hyperplasia thickness was 0.21 +/- 0.1 mm in the device group versus 0.01 mm in the control group. CONCLUSIONS: The GraftConnector provides a consistent and reproducible coronary artery anastomosis and reduces technical demand and manual dexterity in coronary operations. Long-term results demonstrate that off-pump coronary artery bypass grafting performed with the GraftConnector had the same patency rate and luminal width as those performed with running suture.     

A comparison of CO2 laser-assisted venous anastomoses and conventional suture techniques: patency, aneurysm formation, and histologic differences

The expected patency and the potential complications of CO2 laser-welded end-to-end venous anastomoses have not been well established despite increasing clinical interest in the subject. To further study this relatively new technique we used the internal jugular veins (1.0 to 1.4 mm diameter) of 15 New Zealand White rabbits weighing 2.5 to 3.5 kg. On one randomly selected side, a laser-welded end-to-end anastomosis was performed in all animals by placing three equidistant stay sutures followed by welding the vein edges with a CO2 laser (spot size of 0.27 mm, power of 100 mW, and power density of 175 W/cm2). On the contralateral side, the vein was anastomosed with interrupted 10-0 nylon sutures in 10 animals, and in the remaining five animals a continuous 10-0 nylon suture technique was used. All anastomoses were surgically assessed at 30 days after operation. A significantly lower 30-day patency rate (p less than 0.05, Fisher's Exact Test) was found in anastomoses constructed by use of the continuous technique (20%) compared with either interrupted (90%) or the laser-assisted technique (87%). No significant difference was observed in 30-day patency between laser-assisted and conventional interrupted anastomoses. Anastomoses performed with the continuous and the laser-assisted technique required 12.5 +/- 1.3 and 12.9 +/- 3.0 minutes, respectively, whereas those constructed with interrupted technique required 19.1 +/- 4.5 minutes (p less than 0.05, Student-Neuman-Keuls' Test). No evidence of false or true aneurysm was noted in any of the animals. Histologic evaluation of laser-assisted anastomoses demonstrated early full-thickness coagulation necrosis of the wall with reendothelialization by 7 days and complete healing by 30 days after the procedure. Conventional anastomoses showed reendothelialization and minimal necrosis near the sutures at 7 days, but healing was complete by 30 days after the procedure. The patency rate of vein anastomoses performed with the CO2 laser is excellent and superior to the one obtained with continuous sutures, and except for less operating time, the former technique does not appear to offer any significant advantage over the conventional interrupted suture technique for small vein anastomosis in this animal model up to 1 month of follow-up.     

A new probe for the anastomosis of small vessels.

We developed new probes with three varying sizes (phi1.0, 1.5 and 2.0 mm) with a trench for guiding the needle which made small vessel anastomoses easy and suture placement accurate with clear identification of the vessel lumen. We evaluated the efficiency of these probes on anastomoses using the bilateral common carotid arteries of cadaver rabbits. The anastomosis time of end-to-side anastomosis was shortened by using the probe from 20.2+/-3.3 to 15.4+/-2.6 min, and of side-to-side anastomosis from 20.2+/-1.3 to 16.0+/-1.2 min. Of the 5 end-to-side anastomoses without the probe, there was one deformity of the anastomoses site and of the 5 side-to-side anastomoses without the probe, there was one stenosis of the anastomosis. There were neither deformity nor stenosis of the 10 anastomoses of 5 end-to-side and 5 side-to-side anastomoses with the probes. In conclusion, the probe with a trench for guiding the needle made small vessel anastomoses easy.     

Tacrolimus enhances colon anastomotic healing in rats

Tacrolimus inhibits T-cell function and neutrophil chemotaxis during inflammation. We hypothesized that tacrolimus would enhance healing of a rat colon anastomosis by reducing the inflammatory response. Fifty-five male Sprague Dawley rats, 230-260 g body weight, underwent identical surgical manipulation consisting of a single-layer, inverted colon anastomosis and the implantation of osmotic pumps subcutaneously in the left flank area. The animals were randomly assigned to receive tacrolimus, at a dose of 0.01, 0.1, or 1.0 mg/kg/day, or only the control solvent solution. The animals were euthanized 4 days after surgery. Colon-bursting pressure (mmHg), anastomotic collagen content ( micro g hydroxyproline/mg wet tissue), and anastomotic type IV collagenase activity (mU/mg protein) were measured. Tacrolimus significantly increased colon-bursting pressure at all doses used (146 +/- 9, 158 +/- 10, 151 +/- 6 mmHg; 0.01, 0.1, and 1.0 mg/kg/day, respectively) vs. control (119 +/- 7 mmHg, p < 0.01). There was no effect on collagen accumulation except at a dose of 0.01 mg/kg/day, which significantly decreased anastomotic collagen content (p < 0.05). Tacrolimus at a dose of 0.01 mg/kg/day increased anastomotic collagenase activity, which was not changed by treatment with the higher doses. Microscopic examination revealed the preservation of the multilayered structure, including the mucosal muscle, a thickened submucosa, and the proper muscle of the anastomotic site in the tacrolimus-treated groups. These data suggest that tacrolimus enhances wound strength during acute anastomotic healing despite a reduction in collagen content.