Evaluation of the Unilink microvascular anastomotic device in the dog

Nonsuture anastomosis of arteries and veins using the magnetic pinned-ring device: a histologic and scanning electron microscopic study

BACKGROUND

The goal of this study was to evaluate the performance of the magnetic pinned-ring device for nonsuture vascular anastomosis.

METHODS

The magnetic pinned-ring device consists of paired magnetic rings that are coated with titanium nitride and embedded in a polypropylene shell; the rings are equipped with alternately spaced holes and titanium pins. The vascular anastomosis procedure using the novel magnetic pinned-ring device was performed on 14 mongrel dogs, and the traditional hand-sewing technique was used on 14 additional dogs. In situ end-to-end anastomoses were performed in the femoral artery and the inferior vena cava. Patency was confirmed through ultrasonographic scans at different time points as late as 24 weeks after surgery. Gross observation, histological staining, and scanning electron microscopy were used to evaluate the results at 24 weeks postoperatively.

RESULTS

The time required to perform the vascular anastomosis was significantly shorter for the magnetic device than for hand sewing. A continuity of re-endothelialization was confirmed in all anastomotic stomas after 24 weeks, and neither formation of aneurysms nor thickening of the vascular wall was noted. The re-endothelialization was smooth at the anastomotic site of the magnetic device, whereas hand sewing resulted in rough and uneven re-endothelialization and the presence of visible sutures. Moreover, the endothelial cells were regularly arranged at the anastomotic site of the magnetic device, whereas different-sized and irregularly aligned endothelial cells were present at the hand-sewn anastomotic site. Use of the magnetic device was associated with significantly decreased deposition of fibrotic collagen and depressed infiltration of inflammatory cells compared with use of the hand-sewing technique.

CONCLUSIONS

The magnetic pinned-ring device offers a simple, fast, reliable, and efficacious technique for nonsuture vascular anastomosis. Use of this device shortens operation time, maintains a high patency rate, and improves the healing of vascular tissue.

Diode laser-assisted carotid bypass surgery: an experimental study with morphological and immunohistochemical evaluations

OBJECTIVE

Conventional suturing methods of microvascular anastomosis are associated with various degrees of vascular wall damage that can lead to thrombosis and bypass occlusion. An experimental model of double end-to-side venous graft anastomosis on the common carotid artery was set up to compare conventional suturing methods with a low-power diode laser vascular welding technique.

METHODS

The experiments were performed on 40 rabbits that underwent implantation of a 15-mm segment of jugular vein on the common carotid artery. The proximal end-to-side suture was performed by eight interrupted stitches; the distal suture, which was done using a laser welding technique, was supported by four stay sutures. The animals were evaluated after 2 days (n = 15), 9 days (n = 15), and 30 days (n = 10). The vascular segments were excised and subjected to histological, immunohistochemical, and ultrastructural evaluation.

RESULTS

The average clamping time to perform both anastomoses was 35 minutes. At the end of the follow-up period, one case of complete occlusion was observed after 9 days and one case was observed after 30 days. Surgical observations and pathological evaluation indicated that adoption of the laser welding technique reduced operative time and bleeding. Histologically, a reduction of thrombosis, inflammation, myointimal hyperplasia, and dystrophic calcification was observed in laser-assisted anastomoses. A better preservation of the endothelium was also evident in laser-treated anastomoses. The observed differences were deemed statistically significant (P < 0.05).

CONCLUSION

Our study demonstrated the efficacy of diode laser welding in improving surgical techniques of high-flow bypass and in reducing the vascular wall damage observed with conventional methods.

[The ring-pin anastomosis technique. Long-term clinical experiences with the mechanical ring-pin system for microvascular anastomoses in reconstructive head and neck surgery ]

BACKGROUND

Microvascular anastomosis remains one of the most critical aspects of free tissue transfer. Since microsurgical suture techniques are complicated and time-consuming, other techniques of anastomosis have been created. One of these is the ring-pin system.

METHODS

Between January 1996 and October 2001, 48 patients underwent reconstruction with a free radial forearm flap. In 20 patients the venous anastomosis was carried out using a ring-pin system with end-to-end technique. The clinical results were compared to the other 28 patients in whom the anastomosis was sutured with 9-0 prolene.

RESULTS

In the group using ring-pin anastomosis ( n=20), two flaps showed venous congestion within 24 h postoperatively. After revision the flaps were well perfused. In the other group with sutured vessels ( n=28), a transplant became ischemic in one patient due to venous thrombosis and had to be partly removed. The time of anastomosis was considerably shortened by the use of the ring-pin system.

CONCLUSIONS

The venous end-to-end-anastomosis using the ring-pin system can be carried out relatively easily and rapidly after a comparatively short period of training. Long-term results have shown good tissue tolerance of the material and sufficient blood circulation of the grafts.

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.

Vascular anastomosis using a biodegradable device with a heat-shrinking sleeve: a preliminary report

PURPOSE

The objective of this study is to present a simple mechanical anastomosis system capable of uniting vessels of differing diameters and to evaluate its applicability.

MATERIALS AND METHODS

A new mechanical system for anastomosis of small vessels was used in 30 rabbits to join 100 sectioned carotid arteries and jugular veins. The system is resorbable and consists of a cuff and a shrinkable sleeve. To carry out the anastomosis, one vessel end is pulled through the cuff and everted over it. The second vessel end is then slipped over the everted vessel end and the cuff. A heat-shrinking sleeve is positioned over the site and shrunk to produce permanent fixation.

RESULTS

The overall patency rate of the anastomoses was 96.6% in the arteries and 93.3% in veins. Microscopically, the intima-to-intima contact sites were bridged by an endothelial layer in the first postoperative weeks.

CONCLUSION

Advantages of the system include a short insertion time, simple instrumentation, a high patency rate, and resorbability. However, the method requires additional vessel length for eversion, and it cannot be used for end-to-side anastomoses.

The medial saphenous fasciocutaneous free flap in dogs

The purpose of this study was to identify the angiosome of the medial saphenous artery and vein and to evaluate the use of this cutaneous angiosome as a free skin flap in the dog. In phase 1 of this study, selective angiography of the medial saphenous artery performed in six canine cadavers showed that the skin covering the entire medial femorotibial area, the distal half of the caudal head of the sartorius muscle, and the gracilis muscle were perfused by the medial saphenous artery. In phase 2, a medial saphenous fasciocutaneous island flap was raised and sutured back to the skin edges of the donor wound in three dogs. One hundred percent survival of all of the flaps occurred. In phase 3, a medial saphenous fasciocutaneous microvascular free flap was transferred to a wound that was created over the dorsal metacarpal (n = 3) or metatarsal region (n = 3). The mean length +/- SD of the medial saphenous vascular pedicle was 80 +/- 13 mm (n = 5); the mean diameter +/- SD of the medial saphenous artery was 2.8 +/- 0.2 mm (n = 5) and the mean diameter +/- SD of the medial saphenous vein was 4.2 +/- 0.2 mm (n = 5). One hundred percent of all flaps survived (n = 6). Selective angiography or the distal cranial tibial artery (metatarsal wounds, n = 3) and the median artery (metacarpal wound, n = 3) was performed 3 weeks after surgery. All of the vascular anastomoses were patent and neovascularization of the wound beds was present. This free flap was found to be acceptable for cosmetic reconstruction of wounds located on the distal extremity.

Clinical experience with a microvascular anastomotic device in head and neck reconstruction

BACKGROUND

Despite numerous refinements in microsurgical technique and instrumentation, the microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions.

MATERIALS AND METHODS

Concurrent with the development of microsurgical techniques, various anastomotic coupling systems have been introduced in an effort to facilitate the performance and reliability of microvascular anastomoses. The microvascular anastomotic coupling device (MACD) studied here is a high-density, polyethylene ring-stainless steel pin system that has been found to be highly effective in laboratory animal studies. Despite its availability for human clinical use over the last 5 years, reported clinical series remain rare. Our clinical experience with this MACD in 29 head and neck free-tissue transfers is reported herein.

RESULTS

Thirty-five of 37 (95%) attempted anastomoses were completed with 100% flap survival with a variety of donor flaps, recipient vessels, and clinical contexts. Two anastomoses were converted to conventional suture technique intraoperatively, and one late postoperative venous thrombosis occurred after fistulization and vessel exposure.

CONCLUSIONS

We conclude that the MACD studied here is best suited for the end-to-end anastomosis of soft, pliable, minimally discrepant vessels. Previous radiation therapy does not appear to be a contraindication to its use. Interpositional vein grafts may also be well suited to anastomosis with the device. When carefully and selectively employed by experienced microvascular surgeons, this MACD can be a safe, fast, and reliable adjunct in head and neck free-tissue transfer reconstructions, greatly facilitating the efficiency and ease of application of these techniques.

Clinical use of the 3M 2.5 mm mechanical microcoupling device in free tissue transfer

The long-term patency of the 2.5 mm mechanical microvascular anastomotic device (the Unilink system) was evaluated in 10 cases of free flap transfer in nine patients between July 1991 and July 1993. Flap survival indicated adequate patency to time of healing. All cases were considered critical end-to-end venous anastomoses, without a parallel conventional microvascular hand-sewn anastomosis associated with the coupling device. The types of flaps used were seven rectus abdominous and one each of serratus anterior and lateral arm muscles and a free jejunum. There were no postoperative complications requiring reexploration. The 2.5 mm device had a rate of 100% flap take with complete healing at an average of 15 months postoperatively. Selected Doppler flow studies depicted the coupler device in vivo with duplex scan verification of venous patency. The 2.5 mm coupler is a versatile anastomotic device for vessels with a diameter of 2.4-3.2 mm. This expands the applicability of the UNILINK system for use in larger diameter vessels.

Clinical experience with the Unilink/3M Precise microvascular anastomotic device

The Unilink/3M Precise anastomotic device for microvascular anastomoses has been evaluated in 38 critical anastomoses in 26 selected patients. The microvascular anastomosis was usually completed within three minutes by a single surgeon. There was only one failure, when an arterial anastomosis clotted because of a technical error. In all patients tissue survival was dependent on patent mechanical anastomoses (critical anastomoses) and the follow-up period was more than three years.

Long term evaluation of the unilink anastomotic system. A study with light and scanning electron microscopy

The long term effects of the Unilink mechanical microvascular anastomosis in terms of anastomotic patency and histological changes in the vessel wall were evaluated in 10 rabbits. Both carotid arteries and facial veins were divided and reanastomosed with the Unilink device. At death two years later all 40 anastomoses were fully patent, with histological changes similar to those described previously after 16 weeks, that is, normal endothelial lining, but almost total atrophy of the media at the anastomotic site. The thinning of the vessel wall at the anastomosis caused neither occlusions nor aneurysms during the observation period.