The vascular connector, design of a new device for sutureless vascular anastomosis

A Novel Vascular Anastomotic Coupling Device for End-to-End Anastomosis of Arteries and Veins

OBJECTIVE

Hand-sutured (HS) techniques remain the gold standard for most microvascular anastomoses in microsurgery. HS techniques can result in endothelial lacerations and back wall suturing, leading to complications such as thrombosis and free tissue loss. A novel force-interference-fit vascular coupling device (FIF-VCD) system can potentially reduce the need for HS and improve end-to-end anastomosis. This study aims to describe the development and testing of a novel FIF-VCD system for 1.5 to 4.0 mm outside diameter arteries and veins.

METHODS

Benchtop anastomoses were performed using porcine cadaver arteries and veins. Decoupling force and anastomotic leakage were tested under simulated worst-case intravital physiological conditions. The 1.5 mm FIF-VCD system was used to perform cadaver rat abdominal aorta anastomoses.

RESULTS

Benchtop testing showed that the vessels coupled with the FIF-VCD system could withstand simulated worst-case intravital physiological conditions with a 95% confidence interval for the average decoupling force safety factor of 8.2 ± 1.0 (5.2 ± 1.0 N) and a 95% confidence interval for the average leakage rate safety factor of 26 ± 3.6 (8.4 ± 0.14 and 95 ± 1.4 μL/s at 150 and 360 mmHg, respectively) when compared to HS anastomotic leakage rates (310 ± 14 and 2,100 ± 72 μL/s at 150 and 360 mmHg, respectively). The FIF-VCD system was successful in performing cadaver rat abdominal aorta anastomoses.

CONCLUSION

The FIF-VCD system can potentially replace HS in microsurgery, allowing the safe and effective connection of arteries and veins. Further studies are needed to confirm the clinical viability and effectiveness of the FIF-VCD system.

Less-Suture Vascular Anastomosis: Development of Alternative Protocols with Multifunctional Self-Wrapping, Transparent, Adhesive, and Elastic Biomaterials

Blood vessel anastomosis by suture is a life-saving, yet time-consuming and labor-intensive operation. While suture-less alternatives utilizing clips or related devices are developed to address these shortcomings, suture anastomosis is still overwhelmingly used in most cases. In this study, practical "less-suture" strategies are proposed, rather than ideal "suture-less" methods, to reflect real-world clinical situations. In the case of rat artery (d = 0.64 mm) anastomosis, the less-suture anastomosis involves the application of thin, adhesive, transparent, and self-wrapping films to the site. This surprisingly reduces the number of stitches required from ten (without films) to four (with films), saving 27 min of operating time per vessel. Furthermore, the decreased number of stitches largely alleviates fibrosis-mediated wall-thickening. Thus, a less-suture strategy is particularly useful for anastomosis of multiple vessels in emergency conditions and small-diameter vessels.

A systematic review of sutureless vascular anastomosis technologies

Vascular anastomoses typically involve a handsewn technique requiring significant surgical training, expertise, and time. The aim of our systematic review was to identify and describe sutureless vascular anastomosis techniques. We performed a systematic review of all sutureless vascular anastomosis technologies published in MEDLINE, PubMed, Embase, CINAHL, Cochrane, Web of Science, and Scopus Library databases and a patent review using US Patent and Trade Office Application, US Patent and Trademark Office Patent, Google Patents, Lens, Patent Quality Through Artificial Intelligence, SureChEMBL, and E-Space Net. Data from inclusion studies and patents published between January 1, 1980 and July 15, 2021 were abstracted to describe their category, anastomosis type and configuration, study types, and advantages and disadvantages encountered with each technology. Two hundred eleven original studies and 475 patents describing sutureless vascular anastomosis technologies were identified. In the literature, stents/stent-grafts/grafts (n = 61), lasers (n = 53), and couplers (n = 27) were the predominant device categories. In the patent review, adhesive technologies (n = 103), stents/stent-grafts/grafts (n = 68), and mechanical connectors (n = 61) predominated. The majority of studies involved in vivo animal studies (n = 193); 32.2% (n = 68) of investigations involved human trials; and 17.9% (n = 85) of patent technologies were approved by the US Food and Drug Administration. The main advantages described for sutureless anastomosis technologies included faster procedure time and greater patency rates compared with handsewn anastomoses. The main disadvantages included reduced vessel compliance, stenosis, leakage, and device costs. The appeal of sutureless technology is substantiated by numerous animal trials, but their use in humans remains limited. This may be a reflection of strict regulatory criteria and/or vascular complications associated with currently available technologies.

Compression of the vascular wall to create a friction fit in a vascular anastomotic coupler

A previously reported microvascular coupler was shown to effectively create vascular anastomoses, but was too large for practical clinical use. To safely reduce coupler size, certain failure modes needed to be better understood. The coupler functions, in part, by compressing the vessel wall between two concentric rings, creating a friction fit that anchors the device to the vessel. This work investigates the relationship between vessel wall compression and resulting friction fit strength to ensure reducing coupler size will not unduly increase the risk that this friction fit might fail. Vascular walls were compressed to a specified strain and the tensile force required to overcome the resulting friction was measured. Experiments were conducted with various vessel types (Porcine common carotid artery, splenic artery, and jugular vein), across a range of compressive strains (55-95%), and by using either PEEK or HDPE to compress the vessel. Tensile force was increased at a rate of 5 g/min or held constant for 24 h. For experiments with incrementally increasing force, the force at failure varied with compressive strain via a power function. At 70% compression, PEEK produced 4.6 times stronger friction fits than HDPE, and common carotid arteries and splenic arteries produced 1.8 and 1.3 times stronger fits than jugular veins respectively. For experiments where tensile force was applied for 24 h, much lower forces were required to overcome friction. These results were compared to friction fit failure in a coupler prototype and it was found that the prototypes failed at just 30% of the force required to cause vessel slip under the other test conditions. These results were used to develop a model that predicts the probability of device failure via vessel slipping (one design, smaller than previously reported, was estimated to fail at maximum in vivo axial stress once in 500 anastomoses, a potentially safe level of risk).

Mechanical strength and hydrostatic testing of VIVO adhesive in sutureless microsurgical anastomoses: an ex vivo study

Conventional anastomoses with interrupted sutures are challenging and inevitably associated with trauma to the vessel walls. The goal of this study was to evaluate a novel alternative adhesive-based suture-free anastomosis technique that uses an intraluminal stent. Overall, 120 porcine coronary vessels were analyzed in an ex vivo model and were examined for their mechanical (n = 20 per cohort) and hydrostatic strength (n = 20 per cohort). Anastomoses were made using the novel VIVO adhesive with an additional intraluminal nitinol stent and was compared to interrupted suture anastomosis and to native vessels. Sutureless anastomoses withstood pressures 299 ± 4.47 [mmHg] comparable to native vessels. They were performed significantly faster 553.8 ± 82.44 [sec] (p ≤ 0.001) and withstood significantly higher pressures (p ≤ 0.001) than sutured anastomoses. We demonstrate that the adhesive-based anastomosis can also resist unphysiologically high longitudinal tensile forces with a mean of 1.33 [N]. Within the limitations of an in vitro study adhesive-based suture-free anastomosis technique has the biomechanical potential to offer a seamless alternative to sutured anastomosis because of its stability, and faster handling. In vivo animal studies are needed to validate outcomes and confirm safety.

Biomechanical characterization of a novel ring connector for sutureless aortic anastomosis

The surgical treatment for aortic diseases remains a challenge for any cardiac surgeon. The use of sutureless ring connector in aortic anastomosis can simplify the procedure and shorten anastomosis time. Therefore, we developed a novel device for sutureless aortic anastomosis. A series of experiments were carried out for tensile and leakproof-capacity assessments to verify the feasibility of the ring connector by using fresh swine aorta samples. In in vivo test, the ring connector was implanted in 6 swine with follow-up of 6 months. Radiographic and pathological studies of the aorta were performed. In the tensile tests, the strength was 32.7±5.9 Newton (N) in the sutureless anastomosis group, compared with 73.3±12.5 N in the control group by traditional manual suture. In the leakproof-capacity assessment, no sign of either leakage or bursting was evident at 280 mmHg of internal pressure in the aorta samples. In in vivo tests, it took 9.47±0.3 minutes for the sutureless anastomosis, compared with 15.58±1.39 minutes for hand-sewn suturing. Insertion was easy and rapid. Radiographic and pathological studies were performed at first month, third month and sixth month after surgery, each time obtained from the two swine, showed patency of the anastomosis and no signs of stenosis, blood leakage, migration or pseudoaneurysm formation, except one paralyzed swine developed of thrombo-occlusion at the site of the sutureless anastomosis. The result indicates that this novel ring connector offers considerable promise for sutureless aortic anastomosis.

Sutureless open vascular anastomosis connector: An experimental study

The objective of this study was to assess the safety of a new developed sutureless vascular adapter system in a porcine model. In five pigs, 4-cm-long polyester prosthesis (6 mm diameter) were implanted and anastomosed with the newly developed adapter proximally and suture anastomosis distally. The integration of the adapter was investigated in comparison to the suture anastomosis. These investigations were performed by light microscopy and scanning electron microscopy. Median operative time for performing the adapter anastomosis was significantly shorter compared to suture anastomosis (66 s vs. 246 s, p < 0.05). Median estimated blood loss during adapter anastomosis implementation was 22.5 mL (range 19.0–25.0 mL) compared to 48.2 mL (range 45.4–63.5 mL, p < 0.05). In five hand-sewn anastomoses, overall eight additional stitches were necessary whereas all adapter anastomoses showed primary leak tightness. This in vivo study shows the technical feasibility of the newly developed adapter.