Coronary artery bypass-grafting using interrupted anastomosis with the U-clip]

For coronary artery anastomosis, the continuous suture technique is generally used because it is easy to perform, there is less anastomotic leakage, and a shorter anastomotic time compared with the interrupted suture technique. However, with this technique there is a potential risk of anastomotic stenosis caused by the purse-string effect, which does not occur with the interrupted suture technique. The U-Clip device was designed to facilitate the interrupted suture technique in coronary anastomosis by eliminating the need for suture management, knot tying, and surgical assistance. The device employs the superelastic properties of nitinol and two components: 1. a needle/suture delivery system, and 2. a detachable nitinol self-closing wire. We used this device successfully for LITA-LAD anastomosis in MIDCAB. When this device is applied to small caliber conduits, such as the internal thoracic arteries and the gastroepiploic artery, the side-to-side anastomosis can reduce the anastomotic leakage more efficiently, since the coronary incision and graft incision can be perfectly matched. The U-Clip facilitates coronary anastomosis by simplifying and decreasing the amount of manipulation and complexity required in minimally invasive CABG procedures. Nitinol technology also has potential in robotic and endoscopic surgical applications.     

Stapled coronary anastomosis with minimal intraluminal artifact: The S2 Anastomotic System in the off-pump porcine model

OBJECTIVE: A reliable, easy-to-use, 1-shot anastomotic device will significantly push the barrier for less invasive coronary bypass surgery. The current study was designed to test the safety, efficacy, and early patency of a novel distal anastomotic device. METHODS: The S2 Anastomotic System (iiTech BV, Amsterdam, The Netherlands) was used in 10 consecutive pigs (73 kg) on a mild antiplatelet regimen. In each animal, the device was used to create an internal thoracic artery to left anterior descending bypass on the beating heart. The anastomoses were evaluated intraoperatively (n = 10), at 2 days (n = 2), and at 5 weeks (n = 8) by functional flow measurements, postmortem angiography, and histomorphologic examination. RESULTS: In all pigs, the S2 Anastomotic System rapidly created successful anastomoses at the first attempt (graft loading and coronary ischemia time: 1.2 +/- 0.3 minutes and 3.0 +/- 0.6 minutes) on target vessels of 1.6 to 2 mm inner diameter. There were no technical failures or anastomotic leaks requiring additional sutures. Both intraoperatively and at the time of death, ischemically induced peak hyperemic flow responses demonstrated widely patent bypasses, which were confirmed by postmortem angiography (FitzGibbon grade A, n = 10) and macroscopic evaluation (anastomotic orifice: 2 mm). Histomorphologic evaluation showed a normal healing response with negligible neointima covering the connector and limited streamlining repair tissue formation between the staple-like elements of the connector. CONCLUSIONS: The S2 Anastomotic System consistently created automated, fast, and reliable internal thoracic to coronary artery anastomoses on the porcine beating heart with excellent graft patency and healing characteristics at the 5-week follow-up.     

Early experience of coronary artery bypass grafting with a new self-closing clip device

OBJECTIVE: We are in the midst of development of several new anastomotic devices for use in coronary artery bypass grafting surgery. This study was designed to examine one of these devices (a new self-closing clip) for left internal thoracic artery-left anterior descending coronary artery anastomosis. Its feasibility and the quality of anastomosis were evaluated. METHODS: Fourteen patients who underwent first-time elective coronary artery bypass surgery were enrolled between July and December 2000. The left internal thoracic artery was anastomosed to the left anterior descending coronary artery in an interrupted manner with Coalescent U-clips (Coalescent Surgical, Inc, Sunnyvale, Calif). Immediate patency was checked with a transit-time flowmeter. Selective angiography was performed 6 months after surgical intervention. RESULTS: Five patients underwent on-pump coronary bypass grafting, 9 on the beating heart. One patient was excluded from the study intraoperatively because of a poor target site necessitating a 2-cm-long anastomosis. Left internal thoracic artery-left anterior descending artery anastomoses were created with an average of 11.8 clips in 15.9 minutes. Mean graft flow was 45.6 mL/min. Neither conversion to standard suture technique nor revision of anastomosis was necessary. There tended to be a learning curve in the anastomosis on the beating heart. Postoperative lengths of stay in the intensive care unit and the hospital were 20.7 hours and 3.9 days, respectively. Neither death nor major complication was seen, except for temporary atrial fibrillation in 2 patients. Graft patency at 6 months was 100% (FitzGibbon grade A). CONCLUSION: Left internal thoracic artery-left anterior descending artery anastomoses can be created safely and effectively with new self-closing clips on the beating, as well as the arrested, heart. Midterm patency was shown to be perfect by means of angiography.     

Facilitated endoscopic beating heart coronary artery bypass grafting using a magnetic coupling device

BACKGROUND: Suturing of a coronary anastomosis in totally endoscopic coronary artery bypass grafting on the beating heart is technically demanding. The potential benefits of the endoscopic Magnetic Vascular Positioner device (Ventrica, Inc, Fremont, Calif) to facilitate construction of a coronary anastomosis in a closed chest environment were evaluated. METHODS: Totally endoscopic coronary artery bypass grafting on the beating heart was performed in 8 foxhound-beagle inbred dogs with the da Vinci telemanipulation system (Intuitive Surgical, Mountain View, Calif). A prototype of the endoscopic Magnetic Vascular Positioner device was used to facilitate construction of the coronary anastomosis. One pair of magnets was inserted in the internal thoracic artery and left anterior descending artery using robotic instruments to guide and place the endoscopic delivery platform. All animals underwent angiography; gross inspection of the anastomotic site was performed after excision of the hearts. RESULTS: The procedure was accomplished in all animals in 169 minutes (155-190 minutes). Dissection of the left anterior descending coronary artery (6.5 minutes; 1-20 minutes), positioning of the stabilizer (8.5 minutes; 7-16 minutes), placement of occlusion tapes (6 minutes, 3-10 minutes), and arteriotomy 5.5 minutes (3-30 minutes) was achieved without problems. By use of the Magnetic Vascular Positioner device, the anastomosis at the graft site was performed with the graft still in situ. Except for 1 premature deployment, all other deployments were easily accomplished in 3 minutes (1-28 minutes). The following adverse events were encountered: bleeding from the right ventricle caused by occlusion tape (1), anastomotic leakage on reperfusion requiring repair stitches (2), and anastomotic occlusion as a result of thrombus (1). All except 1 animal with a patent graft and anastomosis survived the procedure. The overall patency was 7 of 8. DISCUSSION: The combination of robotic technology allowing for dexterous manipulation in a closed chest environment and a simple yet effective and timesaving technique for anastomotic coupling may facilitate beating heart totally endoscopic coronary artery bypass grafting.     

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.     

Magnetic vascular coupling for distal anastomosis in coronary artery bypass grafting: a multicenter trial

OBJECTIVE: The hand-sewn anastomosis is the "gold standard" for performing coronary artery bypass grafts. However, performing a hand-sewn anastomosis is more demanding and time-consuming when used in less invasive approaches such as small access, totally endoscopic or beating heart surgery. In conjunction with attempts to reduce the surgical trauma of coronary artery bypass grafts by using these less invasive approaches, alternative methods for constructing distal anastomoses should be explored. These data report on predischarge angiographic findings and 30-day clinical follow up of patients who have received a new distal anastomotic device. METHODS: In a multicenter trial, 32 patients (mean age: 65 +/- 9 years; 85% men) requiring multivessel coronary artery bypass surgery had 1 of the anastomoses performed using a novel anastomotic technology. The Magnetic Vascular Positioner System was used in 1 of the bypass grafts and the other bypasses were completed by conventional hand-sewn technique. The Magnetic Vascular Positioner System consists of 4 magnetic, gold-plated implants and 2 delivery devices that facilitate the creation of a functional end-to-side anastomosis. A predischarge angiogram was performed to evaluate graft patency. RESULTS: There were no device-related major adverse events. The application of the Magnetic Vascular Positioner device was successful in 32 of 41 cases (78%). Nine patients were intended for treatment but did not receive the Magnetic Vascular Positioner System. In 5 of the cases the coronary artery was too small; 1 case had a posterior wall plaque in the target artery; and 3 patients had a nonhemostatic anastomosis after coupling of the port and were subsequently converted to hand-sewn anastomoses. The median total Magnetic Vascular Positioner anastomotic time was 137 seconds with a range from 65 to 370 seconds. Overall patency rate of the Magnetic Vascular Positioner anastomosis was 93.5% versus 91.7% (P = not significant) in hand-sewn grafts. One patient (3.1%) died due to low cardiac output but had patent grafts at autopsy. One myocardial infarction (3.1%) occurred the day after a percutaneous transluminal coronary angioplasty of a hand-sewn graft. One prolonged mechanical ventilation (3.1%) was required because of pneumonia and adult respiratory distress syndrome. CONCLUSIONS: Magnetic vascular coupling in coronary surgery is safe and effective and has acceptable early patency rates. This new technique may facilitate beating heart and minimally invasive coronary artery bypass grafts.     

An experimental model of saphenous vein-to-coronary artery anastomosis with the St. Jude Medical stainless steel connector

BACKGROUND: A new stainless steel anastomosis device developed by St. Jude Medical Cardiovascular Group was studied in a canine model. METHODS: In 12 dogs, coronary saphenous vein grafts were made to the left anterior descending coronary artery and to the circumflex coronary artery; one anastomosis was completed with the St. Jude Medical stainless steel connector device, and the other with conventional suturing. A 30-day coronary angiogram was performed in surviving animals, and, after sacrifice, anastomoses were measured, examined grossly, and submitted for histologic study. RESULTS: All 12 animals survived the procedure, and 9 survived to sacrifice at 30 days. Comparing the connector grafts and sutured grafts, no significant differences were found between vessel diameters, intraoperative graft flows, graft patency, and histology. The average loading time for the connector was 8.5 minutes (range 4 to 16 minutes). Mean time for the 12 connector anastomoses was 3 minutes (range 2 to 5 minutes) compared with 8.4 minutes for suture (range 4 to 13 minutes). CONCLUSIONS: The side-to-side stainless steel connector anastomotic device produces a secure anastomosis with minimal variability; compared with suture methods, it is expeditious and has comparable 30-day histology and angiographic results. It promises to be an important addition to the surgical armamentarium for the treatment of coronary artery disease.     

A new method of vascular anastomosis by CO2 laser: experimental and clinical study

It is difficult to maintain the long-term patency after conventional anastomosis especially for the small caliber vessels. Since 15 years we have performed aortocoronary bypass with suture materials for the patients with ischemic heart disease. There are some problems in maintaining the long-term patency of the bypass grafts. Low energy CO2 laser was utilized to make vascular anastomosis with a few stay sutures. Vascular anastomoses (side-to-side, end-to-end, end-to-side) were carefully made by CO2 laser in the regions of the femoral arteries and veins, the carotid arteries and jugular veins in dog. A-C bypass was also successfully carried out between the internal mammary artery and the left anterior descending artery under the beating heart in experiment. Outputs of 20-40 mW and irradiation times of 6-12 sec/mm were optimal conditions for anastomosis of the small caliber vessels. There were no problems in the intensity and the healing of the anastomotic sites in comparison with the conventional suture method. On the basis of these excellent experimental results a low energy CO2 laser was employed clinically for vascular anastomosis of the peripheral vessels in 28 patients with angina pectoris or chronic renal failure and cardiac failure. There were no complications such as bleeding and suture line aneurysm after surgery. In conclusion, vascular anastomosis by laser might be recommended in performing with safety and rapidity for small caliber vessels.     

Experimental laser-assisted end-to-side microvascular anastomosis

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

Automated distal coronary bypass with a novel magnetic coupler (MVP system)

OBJECTIVE: We sought to assess the feasibility of performing sutureless distal coronary artery bypass anastomoses with a novel magnetic coupling device. METHODS: From May 2000 to April 2001, single-vessel side-to-side coronary artery bypass grafting on a beating heart was performed in 39 domestic white pigs (35-60 kg) without the use of mechanical stabilization, shunts, or perfusion bridges. Animals were divided into 2 groups. Seventeen pigs underwent right internal thoracic artery to right coronary artery bypass grafting through a median sternotomy (group 1) with a novel magnetic vascular positioning system (MVP system; Ventrica, Inc, Fremont, Calif). Twenty-two pigs underwent left internal thoracic artery to left anterior descending artery grafting with the MVP anastomotic device through a left anterior minithoracotomy (group 2). This system consists of 2 pairs of elliptical magnetic implants and a deployment device. One pair of magnets forms the anastomotic docking port within the graft; the other pair forms an identical anastomotic docking port within the target vessel. The anastomosis is created when the 2 docking ports magnetically couple. Anastomotic patency was evaluated by means of angiography during the first postoperative week and at 1 month. Histologic studies were performed at different time points as late as 6 months. RESULTS: Right internal thoracic artery to right coronary artery anastomoses and left internal thoracic artery to left anterior descending artery anastomoses were successfully performed with the system in all animals. The self-adherent and self-aligning properties of the implants allowed for immediate and secure approximation of the arteries (total anastomotic time between 2-3 minutes). Anastomoses were constructed without a stabilization platform. Five nondevice-related deaths occurred postoperatively. One-week angiography, performed in 35 surviving animals, showed a patent graft and anastomosis in all cases. The patency rate at 1 month was 97% (33/34). Histologic studies as late as 6 months demonstrated neointimal coverage of the magnets without any significant luminal obstruction. Histology also confirmed the presence of viable tissue between magnets. CONCLUSION: The MVP anastomotic system uses magnetic force to create rapid and secure distal coronary artery anastomoses, which might facilitate minimally invasive and totally endoscopic coronary artery bypass surgery.     

镍钛合金吻合夹吻合血管的扫描电镜观察

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

Mechanisms of occlusion of saphenous vein--coronary artery "jump" grafts.

Seven patients with 12 end-to-side and eight side-to-side saphenous vein graft-to-coronary artery anastomoses were studied at autopsy. Postmortem coronary arteriograms and serial histologic sections of the anastomoses were performed. Occlusive changes occurring in the coronary arteries tended to be at the ends of the arteriotomy and could be attributed to reduction of arterial circumference from its eversion and utilization in the anastomotic connection, or from thrombosis along the suture line or from both. The mechanisms of arterial occlusion were the same in side-to-side and end-to-side anastomoses. In addition to the occlusive changes at the anastomosis, "jump" grafts with two anastomoses were susceptible to rolling or kinking of the graft, apparently as a result of torsion from placement of the side-to-side anastomosis.     

A prospective evaluation of interrupted nitinol surgical clips in arteriovenous fistula for hemodialysis

BACKGROUND: The use of a self-closing nitinol surgical clip (Coalescent Surgical U-Clip) is a novel technique of creating an interrupted vascular anastomosis, which also eliminates the knot tying associated with a conventional vascular anastomosis. The purpose of this study was to compare the clinical outcome of arteriovenous fistulae (AVF) for hemodialysis as constructed using interrupted U-Clip devices and conventional continuous polypropylene sutures. METHODS: We prospectively studied the clinical course of 132 patients (149 access) undergoing either forearm autologous arteriovenous fistula (FAVF, n = 69) or upper arm autologous arteriovenous fistula (UAVF, n = 80) or creations during a 39-month period. Among the FAVF, U-Clips and polypropylene sutures were used in 37 and 32 anastomoses, respectively. Among the UAVF, U-Clips and polypropylene sutures were used in 41 and 30 anastomoses, respectively. Primary patency, complication, and maturation rates were analyzed. RESULTS: Clipped FAVF had an improved maturation rate at 6 weeks (32 of 37, 86%) when compared with sutured FAVF (22 of 32, 69%, P <0.05). There was no difference in the maturation rate among UAVF constructed with either U-Clips or sutures (88% versus 87%, not significant). The primary patency rates at 12, 24, and 36 months were 91%, 84%, and 75% for the clipped FAVF; and 83%, 74%, and 61% for the sutured FAVF (P <0.05) There was no difference in the patency rate of UAVF constructed with either U-Clips or polypropylene sutures at either 12, 24 or 36 moths (91%, 80%, and 75% versus 83%, 77%, and 69%, respectively). CONCLUSIONS: The U-Clips are a viable alternative to sutures for creating vascular anastomosis. It provides a improved maturation and patency rates when compared with the conventional sutured AVF in the forearm. The clinical benefit of the U-Clips may be due in part to the improved compliance created by the interrupted anastomotic technique.     

侧壁横切口小动脉端侧吻合的实验研究与临床应用

我们以家兔腹壁浅动脉与股动脉分别行侧壁横切口和纵切口端侧吻合术为实验模型,对两种吻合方法进行了对比实验研究,结果证明侧壁横切口小动脉端侧吻合术是一种通畅率高,操作相对容易,可有效地预防吻合口痉挛或狭窄,而比较符合血管生理的吻合方法,值得推广应用。并报告了成功地用于临床病例的实践经验。     

侧壁横切口小动脉端侧吻合的实验研究与临床应用

我们以家兔腹壁浅动脉与股动脉分别行侧壁横切口和纵切口端侧吻合术为实验模型，对两种吻合方法进行了对比实验研究，结果证明侧壁横切口小动脉端侧吻合术是一种通畅率高，操作相对容易，可有效地预防吻合口痉挛或狭窄，而比较符合血管生理的吻合方法，值得推广应用。并报告了成功地用于临床病例的实践经验。     

Endoscopic endonasal suturing of dural reconstruction grafts: a novel application of the U-Clip technology. Technical note

Cerebrospinal fluid (CSF) leakage following endoscopic endonasal skull base resection can be a significant problem. A method for securing tissue grafts is needed. In this paper the authors used an endonasal suturing device to secure the graft reconstruction following endonasal tumor resection. The U-Clip anastomotic device (Medtronic), developed for cardiovascular anastomoses, was used to secure the tissue graft to native dura. A specialized needle driver and hemoclip applier were used for the application and deployment of this device. No suture tying was necessary, facilitating its endonasal application. The graft was successfully secured in its desired position to native dura by using the U-Clip anastomotic device. The patient did not suffer a postoperative CSF leak, and postoperative imaging and endoscopy revealed that the graft was in a good position. There was no complication from the use of the device. The U-Clip anastomotic device can be used as a suture device during endonasal surgery. It may prevent tissue graft migration and help prevent CSF leakage.     

Temporary luminal arteriotomy seal: III. Postmortem arteriosclerotic human coronary artery

BACKGROUND: Recently, we described a temporary luminal arteriotomy seal that provided a bloodless arteriotomy without obstructing recipient artery blood flow during bypass grafting in nonarteriosclerotic porcine arteries. This postmortem study assessed the sealing properties in irregular arteriosclerotic human coronary arteries. METHODS: Three hearts were obtained from donated corpses within 24 hours of death. The coronary arteries were pressure-perfused at 60 mm Hg with citrated porcine blood. At 15 anastomosis sites in four different coronary arteries, an end-to-side anastomosis was created using a 200-microm-thick polyurethane seal. Adequacy of sealing was determined at perfusion pressures of 60, 40, and 20 mm Hg. RESULTS: After insertion, the arteriotomy was sealed instantaneously in 10 of 15 anastomoses. After repositioning, complete sealing with a bloodless operative field was obtained in all cases. Low intracoronary transmural pressure did not impede sealing. In 8 of 15 anastomoses, minor leakage without obscuring the arteriotomy edges was observed during anastomotic suturing. Histologic examination revealed no intimal tear or dissection caused by the anastomotic procedure. CONCLUSIONS: In postmortem-obtained arteriosclerotic human coronary arteries, the temporary luminal arteriotomy seal provided optimal visualization of the coronary anastomosis site in combination with persistent distal perfusion.     

Reduction in brain embolization using the Aegis aortic cannula during bypass in swine

BACKGROUND: Although robotically assisted coronary arterial anastomoses are being performed clinically, the short-term and long-term quality and integrity of the left internal thoracic artery (LITA) to left anterior descending artery (LAD) anastomosis remains unknown. The goal of this study was to perform a histologic and angiographic assessment of porcine beating heart LITA to LAD anastomoses using either robotic assistance or a conventional freehand technique. METHODS: Twelve pigs underwent beating heart LITA to LAD anastomoses using either the robotically assisted (n = 6) or conventional freehand techniques (n = 6). Quantitative histologic analysis was performed in all animals in order to determine the degree of vascular wall damage. Selective coronary arteriography was performed in all animals immediately after the procedure in order to evaluate anastomotic patency. The unpaired Student's t test was used for all comparisons between groups. RESULTS: There were no differences in vascular wall damage between the robotically assisted and freehand techniques. Postoperative angiography revealed no stenoses in either group. CONCLUSIONS: Use of the robotically assisted technique for creation of a LITA to LAD anastomosis was not associated with increased histologic damage when compared with the freehand technique in a beating heart porcine model. Furthermore, there was no difference between the two techniques in postoperative patency rate. These results support further clinical investigation of robotically assisted coronary bypass surgery.     

Microvenous thrombosis rates following anastomosis with vein grafting and a knotted suture

An experimental microvenous thrombosis model was developed combining vein grafting in femoral vein defects with exaggerated vessel injuries using a knotted suture in the vessel repair. The rat femoral vein grafts were separately subjected to injuries caused by an anastomosis performed with a suture knotted with eight half-hitches at the distal anastomosis (upstream), the proximal anastomosis (downstream), and both anastomotic sites. These groups were compared to vein grafting done with a standard suture. Vessel patency was assessed at 20 min and 24 hr, and the thrombus component was histologically analyzed at 24 hr after the procedures. One hundred percent of control vein grafts were patent at 24 hr. All experimental groups had significantly decreased patency at 24 hr (P<0.001). Among the experimental groups, knotted suture anastomoses at both anastomoses produced significantly lower patency (13.3%, P<0.05) than knotted suture anastomoses at distal anastomoses. Histological analyses of thrombosed grafts showed that a large amount of thrombocyte deposition and inflammatory cells were noted at both anastomotic sites in the vein grafts with a knotted suture at the distal anastomosis and in the grafts with a knotted suture at both anastomoses. Thrombocyte deposition and inflammatory cells were seen only at the site of proximal anastomosis when using a knotted suture at the proximal anastomosis site alone. This study demonstrated that quantified microvenous thrombosis can be produced by exaggerating vessel injuries with a knotted suture in a vein graft model. This thrombosis model can be used to study the effects of antithrombogenic agents. © 1995 Wiley-Liss, Inc.     

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

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