Preservation of endothelial integrity and function in experimental vascular anastomosis with non-penetrating clips

Calciprotein Particles Induce Endothelial Dysfunction by Impairing Endothelial Nitric Oxide Metabolism

BACKGROUND

Calciprotein particles (CPPs) are associated with the development of vascular calcifications in chronic kidney disease. The role of endothelial cells (ECs) in this process is unknown. Here, we investigated the interaction of CPPs and ECs, thereby focusing on endothelial nitric oxide metabolism and oxidative stress.

METHODS

CPPs were generated in calcium- and phosphate-enriched medium. Human umbilical vein endothelial cells were exposed to different concentrations of CPPs (0-100 µg/mL) for 24 or 72 hours. Ex vivo porcine coronary artery rings were used to measure endothelial cell-dependent vascular smooth muscle cell relaxation after CPP exposure. Serum samples from an early chronic kidney disease cohort (n=245) were analyzed for calcification propensity (measure for CPP formation) and nitrate and nitrite levels (NO_x).

RESULTS

CPP exposure for 24 hours reduced eNOS (endothelial nitric oxide synthase) mRNA expression and decreased nitrite production, indicating reduced nitric oxide bioavailability. Also, 24-hour CPP exposure caused increased mitochondria-derived superoxide generation, together with nitrotyrosine protein residue formation. Long-term (72 hours) exposure of human umbilical vein endothelial cells to CPPs induced eNOS uncoupling and decreased eNOS protein expression, indicating further impairment of the nitric oxide pathway. The ex vivo porcine coronary artery model showed a significant reduction in endothelial-dependent vascular smooth muscle cell relaxation after CPP exposure. A negative association was observed between NO_x levels and calcification propensity (r=-0.136; P=0.049) in sera of (early) chronic kidney disease patients.

CONCLUSIONS

CPPs cause endothelial cell dysfunction by impairing nitric oxide metabolism and generating oxidative stress. Our findings provide new evidence for direct effects of CPPs on ECs and pathways involved.

Reduction of Anastomotic Time Through the Use of Cyanoacrylate in Microvascular Procedures

Background: Ever since the description of the first microvascular anastomosis, numerous alternative methods have been described to the classical approach. Tissue adhesive has shown promising result in previous studies and can be a fast and efficient alternative which still requires more studies to allow its clinical implementation. Methods: A randomized comparative experimental study was conducted on rats' femoral arteries and an end-to-end anastomosis was performed in order to compare 2 anastomosis techniques. In one group, a simple interrupted suture was utilized, whereas in the second group a combination between fewer sutures and tissue adhesive was used. The anastomotic time, total operative time, blood flow velocity before, immediately after and 48 hours after the procedure, as well as an independent grading of the anastomosis immediately after the procedure were performed. Magnetic resonance imaging (MRI) was performed in order to assess the degree of stenosis. After euthanasia, histology and scanning electron microscopy (SEM) were performed on the vessels in order to assess possible complications. Results: A total of 24 anastomoses were performed, of which 12 with a classic technique and 12 with an adhesive technique. All the anastomoses were patent with a significant reduction of anastomotic and total operative time. The grading of the anastomoses showed better results in the classic suture group. The blood flow velocities were not statistically significant between the 2 groups. On MRI there was one stenotic anastomosis, whereas histology and SEM showed more complications on the adhesive group. Conclusion: Anastomotic times were significantly lower with a non-significant trend toward more thrombotic complications in the adhesive group. Further improvement of the glue properties and refinement of the technique will likely make it a viable alternative to interrupted suturing in the future.

Light-Activated Vascular Anastomosis

Background. There have been few advances in technique since vascular anastomosis was performed with silk suture on a curved needle in 1902. This technique results in disruption of the endothelium with exposed intraluminal suture, both of which may lead to thrombocyte aggregation, intimal hyperplasia, and vascular stenosis. A variety of alternative techniques have been explored, with limited success. Photochemical tissue bonding (PTB) is a light-activated methodology of rapidly cross-linking tissue interfaces at the molecular level. Herein, we describe a new technique for anastomosis of venous interposition graft in an ovine model of femoral artery bypass utilizing PTB. Methods. Polypay specific pathogen free sheep (n = 5; 40-45 kg) underwent femoral artery bypass utilizing saphenous vein. The femoral artery was transected and reversed saphenous vein was implanted as an interposition graft. The proximal anastomosis was created as a vein-over-artery cuff utilizing PTB, and the distal anastomosis was created with standard interrupted 8-0 polypropylene suture. Four weeks post-index operation, femoral angiogram was performed to evaluate patency, tortuosity, and luminal diameter. All bypass grafts were harvested and longitudinal and transverse histological sections from the proximal anastomosis were analyzed. Results. The PTB anastomoses (n = 5) were immediately watertight and patent. All animals survived the 28-day study duration. Angiography revealed patent grafts with no aneurysm or stenosis (n = 5). Histologic examination revealed integration of the venous endothelium with the arterial adventitia. Conclusion. Photochemical tissue bonding creates an immediate strong, watertight vascular anastomosis that can withstand physiologic arterial pressure and remains patent at 28 days without the need for intraluminal suture.

Rapid M1 Hemoclips Arteriotomy Repair After Emergency Coil Embolectomy

BACKGROUND

The vascular closure staple clips have been studied in animal models and shown to have comparable results with sutured repair when it comes to the healing process, degree of vessel narrowing, and risk of thrombosis. However, they are clearly superior when the speed of application is taken into account, and they were clinically used in many vascular repair processes. Nevertheless, their usefulness in intracranial vascular surgery has not been described.

OBJECTIVE

To describe the usefulness of hemoclips in fast and efficient repair of medium-sized and large intracranial vessels.

METHODS

Two female patients diagnosed with giant symptomatic cavernous sinus aneurysms were undergoing elective endovascular procedures that were complicated by the dislodgement of coils into the M1 segment of the middle cerebral artery. Both patients were treated performing M1 arteriotomies and coil embolectomy. To avoid prolonged temporary occlusion in the M1 perforator's territory, the arteriotomies were repaired using microhemoclips in less than 10 min with re-establishment of flow.

RESULTS

In both patients, flow was re-established in the M1 segments. In 1 patient, the coils extended to the temporal M2 causing intimal injury and leading to diminished flow. M1 segments in both patients were patent on later angiographic studies.

CONCLUSION

We describe the advantage of emergent cerebrovascular arteriotomy and embolectomy in a rapid repair process that helped avoid massive ischemic injury. We believe this technique should be added to the armamentarium of neurosurgical cerebrovascular options.

Creation of Native Arteriovenous Fistulas with Interrupted Anastomoses Using a Self-Closing Clip Device - One Clinic's Experience

The nitinol U-CLIP™ Anastomotic Device (Coalescent Surgical, Inc., Sunnyvale, CA) is a self-closing penetrating vascular clip that reduces suture management and eliminates knot tying, thus enabling rapid and precise interrupted suture placement and facilitating creation of an optimal vascular anastomosis. This report describes the use of U-CLIP devices in the surgical creation of native arteriovenous fistulas in 68 chronic hemodialysis patients. Overall, 61 of the 65 fistulas created matured successfully within 8–9 weeks. Radial cephalic fistulas: 93% were mature at 8 weeks. Brachiocephalic fistulas: 69% were mature at 8 weeks. One-stage basilic vein transposition: 100% were mature at 9 weeks. Two-stage basilic vein transposition: 100% were mature at 8 weeks after second stage. The results in this report show the excellent performance of U-CLIP vascular clips in the creation of several types of native arteriovenous fistulas in chronic hemodialysis patients. The fistulas created using the U-CLIP devices had a high maturation rate within a relatively short time period, and provided uniformly high flow rates. The patients in this study were a challenging population, with a high incidence of diabetes mellitus (81% of the patients) and vein sizes that were smaller than typically used for fistula creation. The U-CLIP™ Anastomotic Device offers the opportunity to create superior interrupted anastomoses for AV fistulas, even in patients who would otherwise be considered poor candidates for fistula creation.

Utility of nonpenetrating titanium clips for dural closure during spinal surgery to prevent postoperative cerebrospinal fluid leakage

OBJECT

The nonpenetrating titanium clip has been successfully used in peripheral arterial bypass surgery. The purpose of this study was to evaluate the leakage pressures and patterns of nonpenetrating titanium clips using a simple model that mimicked spinal surgery. In addition, the authors describe their surgical experience with these clips and the follow-up results in 31 consecutive patients.

METHODS

The authors compared nonpenetrating titanium clips and expanded polytetrafluoroethylene (ePTFE) sutures in relation to the water pressure that could be tolerated by sutured ePTFE sheets, and the leakage pressure patterns were determined. The changes in leakage pressures at 5 minutes, 30 minutes, and 12 hours were examined when the clips and sutures were used in combination with the mesh-and-glue technique in an in vitro study. Thirty-one patients underwent spinal intradural procedures using nonpenetrating titanium clips to suture the dura maters using the meshand-glue technique, involving fibrin glue and polyglycolic acid-fibrin sheets.

RESULTS

A significant difference was apparent between the ePTFE suture group and the nonpenetrating titanium clip group, with the latter showing a leakage pressure that could be sustained and was 1508% higher than that of the former (p = 0.001). In relation to leakage patterns, the nonpenetrating titanium clips did not make any suture holes in the ePTFE sheet and fluid leakage occurred between the clips, whereas fluid leakage was associated with the pressure elevation that occurred at the suture holes made by the ePTFE sutures. Of the 31 patients who underwent spinal intradural procedures using nonpenetrating titanium clips, 1 (3.2%) experienced cerebrospinal fluid (CSF) leakage postoperatively. No other complications-for example, allergic reactions, adhesions, or infections--were encountered.

CONCLUSIONS

The interrupted placement of nonpenetrating titanium clips enables dural closure without creating any holes. These clips facilitate improvements in the initial leakage pressure and reduce postoperative CSF leakage following spinal surgery. The authors conclude that it is very beneficial to suture the spinal dura mater using nonpenetrating titanium clips given the anatomical characteristics of the spinal dura mater and the fact that the clips do not create suture holes.

"Extremely minimally invasive": recent advances in nanotechnology research and future applications in neurosurgery

The term "nanotechnology" refers to the development of materials and devices that have been designed with specific properties at the nanometer scale (10(-9) m), usually being less than 100 nm in size. Recent advances in nanotechnology have promised to enable visualization and intervention at the subcellular level, and its incorporation to future medical therapeutics is expected to bring new avenues for molecular imaging, targeted drug delivery, and personalized interventions. Although the central nervous system presents unique challenges to the implementation of new therapeutic strategies involving nanotechnology (such as the heterogeneous molecular environment of different CNS regions, the existence of multiple processing centers with different cytoarchitecture, and the presence of the blood-brain barrier), numerous studies have demonstrated that the incorporation of nanotechnology resources into the armamentarium of neurosurgery may lead to breakthrough advances in the near future. In this article, the authors present a critical review on the current 'state-of-the-art' of basic research in nanotechnology with special attention to those issues which present the greatest potential to generate major therapeutic progresses in the neurosurgical field, including nanoelectromechanical systems, nano-scaffolds for neural regeneration, sutureless anastomosis, molecular imaging, targeted drug delivery, and theranostic strategies.

Microvascular sutureless adhesive bonding anastomosis with a new soluble hollow stent

The aim of this study was to assess a new soluble hollow stent used in an experimental sutureless adhesive bonding technique for microvascular anastomosis. Twenty-four New Zealand white rabbits were randomized into 2 groups. Twelve end-to-end anastomoses of carotid arteries were performed with glue and stent in group A. In control group B, 12 anastomoses were performed by manual suturing. Anastomoses were timed; immediate and late patency at 1 day, 7 days, and 3 weeks after surgery were evaluated by ultrasonography. Specimens were then analyzed histologically. This adhesive bonding technique took 7.02 ± 1.26 minutes to perform while the hand-sewn technique took 15.48 ± 2.10 minutes. Immediate and late patencies of the 2 groups were not statistically different. The new technique using glue and stent appeared to be timesaving, feasible, and efficient.

The effects of stenting on shear stress: relevance to endothelial injury and repair

Stent deployment following balloon angioplasty is used routinely to treat coronary artery disease. These interventions cause damage and loss of endothelial cells (EC), and thus promote in-stent thrombosis and restenosis. Injured arteries are repaired (intrinsically) by locally derived EC and by circulating endothelial progenitor cells which migrate and proliferate to re-populate denuded regions. However, re-endothelialization is not always complete and often dysfunctional. Moreover, the molecular and biomechanical mechanisms that control EC repair and function in stented segments are poorly understood. Here, we propose that stents modify endothelial repair processes, in part, by altering fluid shear stress, a mechanical force that influences EC migration and proliferation. A more detailed understanding of the biomechanical processes that control endothelial healing would provide a platform for the development of novel therapeutic approaches to minimize damage and promote vascular repair in stented arteries.

Heterotopic renal transplantation in piglets using vascular closure stapler metallic clips or conventional suturing techniques: comparison of vessel growth and macroscopical study

BACKGROUND/PURPOSE

Our aim was to perform a macroscopic and imaging (ultrasonographic and angiographic) evaluation of vascular closure stapler (VCS) metallic clips for renal transplantation in growing piglets to assess their role for transplantation surgery in young children. If these techniques are to be useful, it is necessary to prove that their use avoids one of the main pitfalls of conventional sutures in this setting, namely lack of growth in the suture line.

METHODS

Twenty-four piglets were used for this study. Animals were subjected to a heterotopic renal autotransplantation when they were 45 days old. The right kidney was moved from its normal location to the cranial area of the iliac fossa. The end-to-side anastomoses between the renal artery and vein and the aorta and vena cava, respectively, were performed using VCS metallic clips in 6 animals. Continuous polypropylene suturing was used in another 6 piglets, and continuous polyglycolic acid suture was used in 6 additional piglets. A control group of 6 animals without renal autotransplantation was also included in the study. All animals were allowed to grow for 6 months, during which time serial angiographic and ultrasonographic studies were carried out to assess the existence of vascular flow disturbances or stenosis. Similarly, angiographic measurements were obtained to document growth at the anastomotic site. Longitudinal growth was evaluated postmortem after the 6-month growing period.

RESULTS

Angiography showed significant (P < .001) transverse growth in both arteries and veins belonging to the VCS clips, running absorbable suture, or control groups. No significant difference was observed among the 3 groups. Vascular growth in the running nonabsorbable suture (polypropylene) group, however, was significantly less than in the other 3 groups and did not significantly differ from baseline. Baseline luminal diameters at the anastomotic site as measured by angiography in the VCS group were 3.64 ± 0.40 mm in the artery and 5.30 ± 1.43 mm in the vein. After growth, these values increased to 6.87 ± 0.90 mm and 11.27 ± 2.53 mm, respectively. Significant longitudinal growth was evidenced macroscopically after 6 months in both aorta and vena cava in all groups. On the other hand, significant longitudinal growth in the renal artery and vein were only observed in the control, VCS, and absorbable suture groups.

CONCLUSIONS

In this experimental setting, satisfactory macroscopic and angiographic vascular growth results were obtained using the VCS clips, suggesting that this suture could be the technique of choice in pediatric transplantation surgery.

Tissue fusion, a new opportunity for sutureless bypass surgery

Microsurgical suturing is the standard for cerebral bypass surgery, a technique where temporary occlusion is usually necessary. Non-occlusive techniques such as excimer laser-assisted non-occlusive anastomosis (ELANA) have certainly widened the spectrum of treatment of complex cerebrovascular situations, such as giant cerebral aneurysms, that were otherwise non-treatable. Nevertheless, the reduction of surgical risks while widening the spectrum of indications, such as a prophylactic cerebral bypass, is still a main aim, that we would like to pursue with our sutureless tissue fusion research. The primary concern in sutureless tissue fusion- and especially in tissue fusion of cerebral vessels- is the lack of reproducibility, often caused by variations in the thermal damage of the vessel. This has prevented this novel fusion technique from being applicable in daily surgical use. In this overview, we present three ways to further improve the laser tissue soldering technique.In the first section entitled "Laser Tissue Soldering Using a Biodegradable Polymer," a porous polymer scaffold doped with albumin (BSA) and indocyanine green (ICG) is presented, leading to strong and reproducible tensile strengths in tissue soldering. Histologies and future developments are discussed.In the section "Numerical Simulation for Improvement of Laser Tissue Soldering," a powerful theoretical simulation model is used to calculate temperature distribution during soldering. The goal of this research is to have a tool in hand that allows us to determine laser irradiation parameters that guarantee strong vessel fusion without thermally damaging the inner structures such as the intima and endothelium.In a third section, "Nanoparticles in Laser Tissue Soldering," we demonstrate that nanoparticles can be used to produce a stable and well-defined spatial absorption profile in the scaffold, which is an important step towards increasing the reproducibility. The risks of implanting nanoparticles into a biodegradable scaffold are discussed.Step by step, these developments in sutureless tissue fusion have improved the tensile strength and the reproducibility, and are constantly evolving towards a clinically applicable anastomosis technique.

BioWeld® Tube and surgical glue for experimental sutureless venous microanastomosis

Background

The medial wall of mammalian veins is generally thin and fragile compared with the thick muscle seen in arteries. This makes venous microanastomoses time consuming and challenging. This study aimed to determine the feasibility and effectiveness of using the BioWeld® Tube in conjunction with a surgical glue (butyl-2-cyanoacrylate) in performing sutureless venous microanastomoses.

Methods

The feasibility and effectiveness of microvascular anastomoses in a rabbit jugular vein model were investigated in six animals, using the BioWeld® Tube in conjunction with butyl-2-cyanoacrylate surgical glue. Patency and tissue repair mechanisms at the anastomotic site were assessed 1 week after the procedure.

Results

All anastomoses remained patent at 1 week. Muscle necrosis occurred only in areas where the tissue was subject to the fold-and-bond procedure.

Conclusion

The study showed the feasibility and short-term effectiveness of the BioWeld® Tube in facilitating venous anastomoses.

Thermal model for optimization of vascular laser tissue soldering

Laser tissue soldering (LTS) is a promising technique for tissue fusion based on a heat-denaturation process of proteins. Thermal damage of the fused tissue during the laser procedure has always been an important and challenging problem. Particularly in LTS of arterial blood vessels strong heating of the endothelium should be avoided to minimize the risk of thrombosis. A precise knowledge of the temperature distribution within the vessel wall during laser irradiation is inevitable. The authors developed a finite element model (FEM) to simulate the temperature distribution within blood vessels during LTS. Temperature measurements were used to verify and calibrate the model. Different parameters such as laser power, solder absorption coefficient, thickness of the solder layer, cooling of the vessel and continuous vs. pulsed energy deposition were tested to elucidate their impact on the temperature distribution within the soldering joint in order to reduce the amount of further animal experiments. A pulsed irradiation with high laser power and high absorbing solder yields the best results.

Laser-assisted end-to-end BioWeld anastomosis in an ovine model

The BioWeld tube, an albumin-based exovascular stent, has been used for microsurgical anastomoses and compared to conventional sutures. The study presented investigated the potential of the BioWeld tube for vascular anastomosis in larger vessels. Laser-assisted BioWeld anastomoses were compared to conventional-sutured anatomoses of the carotid artery of Merino-x ewes. The BioWeld procedure resulted in 100% survival and 100% patency at 1 and 6 week post-operative periods, with no noticeable foreign body response. Sutured animals showed 100% survival and patency. The ischemic time for BioWeld anastomosis averaged 15 minutes compared with 10 minutes for sutures. This study indicates that the BioWeld tube is an easy to use anastomotic technique with equivalent success rates and comparable anastomotic times.

Vein graft anastomoses with magnets

BACKGROUND

Performing vascular anastomoses requires complete circumferential access and is time-consuming and technically challenging. The purpose of our study was to assess a sutureless magnetic device for anastomosing vein grafts.

METHODS AND RESULTS

Oval magnets with a lumen were placed in six male foxhounds. The femoral artery was ligated and an 8 cm length of femoral vein was harvested and reversed. After a 4 mm venotomy or arteriotomy, one magnet was inserted into each vessel lumen and a second magnet was placed outside the vessel but aligned directly over the intraluminal magnet, forming a magnetic port in each vessel. The graft and target vessels were then allowed to self-align and seal, creating a side-to-side anastomosis. Patency was confirmed with duplex Doppler ultrasound scans after 6 and 13 weeks and during explantation after 14 weeks. At that time, the contralateral femoral vein was harvested and an acute graft was created as a control. Macroscopically there was no sign of stenoses or aneurysms. After explant, saline was perfused through all grafts and the hydrodynamic resistance was quantified. There was no significant difference in resistance between the acute and 14-week grafts indicating stenosis. Microscopic examination of 14-week anastomoses showed that all blood-contacting surfaces were well-endothelialised.

CONCLUSIONS

The magnetic vascular coupler allowed sutureless anastomoses between blood arteries and veins. This device might prove useful for anastomosis of large and small vessels, as well as for anastomosis or approximation of non-vascular structures such as peripheral nerves, fallopian tubes or ureters.

Vascular Closure Stapler Clip Anastomosis Decreases Aortic Cross-Clamping Time Compared to Interrupted Nonabsorbable and Running Absorbable Sutures in Growing Pigs

The latest generation in titanium clip application systems, the vascular closure staples (VCS) system avoids intimal lesions and therefore minimizes the subsequent hyperplastic reaction, while at the same time enhancing distensibility and vascular growth. Moreover, VCS clips allow the surgeon to perform vascular anastomosis easily and faster than conventional suture. This system may become the option of choice for vascular reconstruction in pediatric surgery where, as in the case of aortic and transplant surgery, decreasing vascular occlusion times may influence the outcomes. The aim of this study was to determine whether VCS metallic clips would allow shorter anastomosis times than conventional interrupted polypropylene or running Dexon suturing in end-to-end anastomosis performed in the abdominal aorta of young pigs. Twenty-four domestic swine, 45 days old, were used for this study. All animals were subjected to an end-to-end anastomosis in the abdominal aorta using VCS clips, interrupted polypropylene, or running Dexon suture. Aortic cross-clamping time was significantly shorter in the VCS clips group (4.02 +/- 0.72 min), compared to interrupted polypropylene (21.89 +/- 1.93 min) or running Dexon (9.82 +/- 3.97 min) suture. VCS clips are easy to use, and therefore may aid surgeons to significantly decrease the time needed for performing an end-to-end anastomosis in the abdominal aorta, thus decreasing cross-clamping time when compared to interrupted polypropylene or running Dexon sutures.

Vascular Closure Stapler Clips Versus Polypropylene Sutures in End-to-End Anastomoses of Growing Arteries and Veins

Alternatives are still being sought in vascular surgery to avoid the complications caused in growing vessels by the various suture techniques and materials currently in use. A major complication is arrested growth following anastomosis. Opinions differ widely regarding the best approach to this problem, and research is currently underway at our center on the latest generation of clip appliers (vascular closure stapler, or VCS) and their potential application as an alternative to the conventional suture technique in pediatric vascular surgery. This study compared vascular growth and reendothelialization following anastomosis of growing arteries and veins using VCS clips versus the conventional interrupted polypropylene suture technique. Thirty 55-day-old lambs underwent end-to-end anastomosis of the carotid artery and jugular vein. Serial ultrasonography and angiography were carried out over the ensuing 6-month growth period, after which the lambs were euthanized. Gross examination of the anastomosis site was followed by histologic examination involving light microscopy, immunohistochemical techniques, and transmission electron microscopy. Although both VCS clips and polypropylene sutures allowed transverse vessel growth, the clips did not penetrate the intima and thus provided enhanced reendothelialization. The satisfactory results obtained here, as in earlier studies, increasingly point to VCS clips as the method of choice in pediatric vascular surgery.

Randomized clinical trial of continuous sutures or non-penetrating clips for radiocephalic arteriovenous fistula

Background

Despite several modifications to the original design, patency rates of radiocephalic arteriovenous fistulas have changed little since the first report in 1966. The use of non-penetrating clips for vascular anastomosis on the outcome of such fistulas was studied.

Methods

Between January 2000 and August 2003, 107 primary radiocephalic fistulas were constructed in 98 patients. The vascular anastomoses were performed at random with either sutures (n = 56) or clips (n = 51).

Results

Although there were trends for better primary and primary assisted patency of clipped fistulas, the differences were not statistically significant. The 6-month primary patency rate was 61 per cent with sutures and 69 per cent with clips (P = 0·393). The mean(s.d.) primary patency was 315(306) and 285(285) days for clipped and sutured fistulas respectively. With regard to secondary patency, clipped fistulas were better (P = 0·009). The mean(s.d.) secondary patency was 435(376) and 344(316) days for clipped and sutured fistulas, respectively. There were no significant differences in flow characteristics, number of revisions or other morbidity.

Conclusion

This randomized clinical trial provided further evidence that the use of vascular clips may improve the patency rate of radiocephalic arteriovenous fistulas for haemodialysis.

Five years' world experience with nonpenetrating clips for vascular anastomoses

BACKGROUND

A new sutureless technique has been introduced clinically to facilitate the process of vascular reconstruction and improve patency. The Vessel Closure System (VCS) is nonpenetrating, creates an elastomeric everted anastomosis, and is easily and reproducibly applied. The objective of this report is to review the published world experience that has accrued regarding these clips with attention to the assets, liabilities, and pitfalls associated with the new technology.

DATA SOURCES

Medline search and manual cross-referencing were performed, after which 61 original articles were identified on the use of VCS clips for vascular anastomoses.

RESULTS

Advantages of the clips compared with sutures include the technical ease of application, the reduced anastomotic time, the superior hemodynamics, and the improved healing pattern of the anastomosis. Disadvantages include the potential problems in atherosclerotic vessels, lack of prospective randomized long-term follow-up, and initial costs. The best clinical results have been achieved in microvascular repair, as well as with vascular access and transplantation surgery.

CONCLUSIONS

The VCS clip technology has become an accepted vascular anastomosing technique, which in future could lead to the use of clips as a standard approach and the use of sutures only in case of severe atherosclerosis and other circumstances in which vessel edges are difficult to evert.

Non-suture methods of vascular anastomosis

BACKGROUND

The main aim of performing a vascular anastomosis is to achieve maximal patency rates. An important factor to achieve that goal is to minimize damage to the vessel walls. Sutures inevitably induce vascular wall damage, which influences the healing of the anastomosis. Over time, several alternatives to sutures have become available.

METHODS

A Medline literature search was performed to locate English, German and French language articles pertinent to non-suture methods of vascular anastomosis. Manual cross-referencing was also performed and many historical articles were included.

RESULTS AND CONCLUSION

The non-suture techniques can be categorized into five groups based on the materials used: rings, clips, adhesives, stents and laser welding. With all these techniques a faster and less traumatic anastomosis can be made compared with sutures. However, each device is associated with technique-related complications. As a consequence, suturing continues to be the standard approach. The disadvantages of the non-suture techniques include: rigidity and a non-compliant anastomosis with rings; toxicity, leakage and aneurysm formation with adhesives; early occlusion with stents; cost, reduced strength in larger-sized vessels and demand for surgical skills with laser welding. Further refinement is needed before widespread adoption of these techniques can occur. Clips, however, may be particularly promising but long-term evaluation is required.

Clinical experience with non-penetrating vascular clips in free-flap reconstructions

To date, the gold standard for performing a microvascular anastomosis has been the penetrating suture with attached needle. During the last two decades, non-penetrating techniques have been introduced, including the Unilink system for end-to-end anastomoses, and the VCS clip-applier system for both end-to-end and end-to-side anastomoses. The aim of this study was to compare the results of different techniques used to create microvascular anastomoses in free-flap reconstructions. Between January 1995 and October 1999, we performed 474 microvascular anastomoses in 216 consecutive free-tissue transfers. The anastomosis techniques included manual sutures (42%), Unilink rings (34%) and VCS clips (24%). Seven combined sutured-clipped anastomoses were excluded from further analysis. The mean anastomotic time when rings were applied was significantly shorter than when using clips (P 0.0001) or sutures (P 0.0001). Venous anastomoses using clips took less time than those using sutures (P 0.05). There were 19 anastomotic failures, all of which lead to early flap failure. Ten flaps were salvaged by early reoperation; nine flaps were lost. Three more flaps were lost as a result of other causes, bringing the flap survival rate down to 94.4%. Early flap failure was caused by failure of the arterial anastomosis in eight cases; all of them were sutured (these represented 5% of all arterial anastomoses with sutures). None of the clipped arterial anastomoses failed. Early flap failure was caused by failure of the venous anastomosis in 11 patients. Three of these anastomoses were sutured (representing 6% of all venous anastomoses with sutures), seven were anastomosed with rings (representing 5% of all venous anastomoses with rings) and one was clipped (representing 2% of all venous anastomoses with clips). Both the VCS clip-applier system and the Unilink system are easy to handle and allow fast microvascular anastomoses without intraluminal penetration. The patency rate of clipped vessels is at least as good as the patency rates of vessels anastomosed using sutures or rings.