Temporary assisting suspension suture technique for successful microvascular anastomosis of extremely small and thin walled vessels for mice transplantation surgery

Validation of Novel Microsurgical Vessel Anastomosis Techniques: A Systematic Review

INTRODUCTION

 Thorough validation of novel microsurgical techniques is deemed essential before their integration into clinical practice. To achieve proper validation, the design of randomized controlled trials (RCTs) should be undertaken, accompanied by the execution of comprehensive statistical analyses, including confounder adjustment and power analysis. This systematic review aims to provide an encompassing overview of the validation methodologies employed in microsurgical studies, with a specific focus on innovative vessel anastomosis techniques.

METHODS

 A literature search was conducted in PubMed for articles describing the validation of novel microsurgical vessel anastomosis techniques in animal or human subjects.

RESULTS

 The literature search yielded 6,658 articles. A total of 6,564 articles were excluded based on title and abstract. Ninety-four articles were assessed for full-text eligibility. Forty-eight articles were included in this systematic review. Out of 30 comparative studies, 9 studies validated novel modified interrupted suture techniques, 6 studies modified continuous techniques, 6 studies modified sleeve anastomosis techniques, 1 study a modified vesselotomy technique, 7 studies sutureless techniques, and 1 study a modified lymphaticovenular anastomosis technique. Twenty-eight studies contained animals (n = 1,998). Fifteen animal studies were RCTs. Two studies contained human/cadaveric subjects (n = 29). Statistical power analysis and confounder adjustment were performed in one animal study. Out of 18 noncomparative studies, 5 studies validated novel modified interrupted suture techniques, 1 study a modified continuous technique, 2 studies modified sleeve anastomosis techniques, 4 studies modified vesselotomy techniques, 4 studies sutureless techniques, and 2 studies modified lymphaticovenular anastomosis techniques. Ten studies contained animal subjects (n = 320), with two RCTs. Eight studies contained human subjects (n = 173). Statistical power analysis and confounder adjustment were performed in none of the animal or human studies.

CONCLUSION

 The current methods of microsurgical technique validation should be reconsidered due to poor study design. Statistical analysis including confounder adjustment and power analysis should be performed as a standard method of novel technique validation.

Dual intravascular stent flipping technique for microvascular anastomosis

The anastomosis of vessels <0.5 mm in diameter is challenging. We developed a supermicrosurgical anastomosis technique, the dual intravascular stent flipping technique with a double or single clip (dual flipping technique, double-clip technique, and single-clip technique). In the dual flipping technique, we used a 7-0 nylon intravascular stent and clipped the vessel along with the nylon. The double-clip technique was performed in 10 rats with 20 saphenous and 15 superficial inferior epigastric arteries. Immediate and 1-week patency rates were assessed. Subsequently, we examined ten epigastric arteries in five rats with the single-clip technique. The clinical application was performed in six cases involving finger/fingertip amputations, two cases involving radial artery superficial palmar branch flap, and one case involving superficial circumflex iliac artery perforator flap. Using the double-clip technique, the immediate patency rate was 90% and 93% in the saphenous and superficial epigastric arteries, respectively, whereas the 1-week patency rate was 81%. With the single-clip technique, the immediate patency rate was 100%. The replantation and flaps were successful. The advantages of the dual flipping technique included easy insertion, rare slipping-out possibility, and spontaneous vessel dilation by the flipped nylon. Additionally, the posterior vessel wall could be sutured more easily than could the anterior wall. By using the elasticity of the thread to invert the blood vessel, the posterior wall can be sutured without the double clip. When forceps tip insertion into the lumen is difficult, the dual flipping technique enables a relatively easy anastomosis if the 7-0 nylon is inserted into the vessel lumen.

Supermicrosurgical Suture-Stent Technique for A Lymphaticovenular Bypass

Background: Lymphaticovenular anastomosis (LVA) is a challenging procedure and requires a sophisticated supermicrosurgical technique. The aim of this study was to evaluate and establish a discrete supermicrosurgical anastomosis method using the “suture-stent technique”. Methods: Forty-eight LVA sites of twenty patients with lower extremity lymphedema who had undergone LVA between July 2020 and January 2021 were included in this study. LVA was performed with the conventional technique or with the suture-stent technique. The patency of the anastomoses was evaluated using an infrared camera system intraoperatively. The success rate on the first try and the final success rate for each group were compared. Results: After full application of the exclusion criteria, 35 LVAs of 16 patients including 20 limbs were included in the analysis. The ratio of good patency findings after anastomosis in the suture-stent technique group was 100%. The incidences of leakage or occlusion on the first try were statistically greater in the conventional technique group (29.4%) than in the suture-stent technique group (0%) (p = 0.0191). All anastomoses achieved good patency in the final results. Conclusion: With its minimal risk of catching the back wall during the anastomosis, the suture-stent technique can be considered an optimal anastomosis option for LVA.

A simplified cuff technique for abdominal aortic transplantation in mice

BACKGROUND

Allograft arteriopathy is still a leading cause of late organ failure. The aortic allograft model in mice has been used to study chronic rejection and has given useful information in the development of graft arteriosclerosis. However, the technical difficulties of small vessel anastomoses still continue to limit its widespread use. We introduce a new simple method for aortic transplantation in mice.

METHODS

The descending aorta or infrarenal aorta from the donor mouse was anastomosed to the infrarenal aorta using a cuff technique. Aortic transplantation was performed in 30 mice, 10 isografts and 20 allografts. No immunosuppression was administered, and the recipients were sacrificed at day 28. The grafts were histologically analyzed.

RESULTS

Implantation of grafts could be completed in an average of 23 min. There was no technical failure in all 60 anastomoses. The overall survival rate was 93.3%. Histology of aortas revealed typical aspects of chronic rejection in the allografts at day 28. No significant lesion was observed in isografts.

CONCLUSIONS

We have developed an innovative, stable, and simple aortic transplantation model in mice, which is useful for vascular research in transplantation and beyond.

Supermicrosurgery and hyaluronic acid: experimental feasability study of a new method

INTRODUCTION

As a technique of anastomosis for vessels of less than 0.8mm in diameter, supermicrosurgery has aroused renewed interest on account of its potential clinical applications. The technical difficulty of surgery at such a small scale necessitates exploration of new methods likely to render the anastomoses accessible and reliable. The aim of this article is to present the results of an experimental study on the feasibility of anastomoses (arterial diameter ≤0.5mm), assisted by the injection of hyaluronic acid (HA).

MATERIALS AND METHODS

Ten end-to-end arterial anastomoses of the inferior epigastric artery (diameter ≤0.5mm) were performed in 5 rats. An injection of HA had previously been carried out in the vessel lumen and the sutures were made with 12-0 nylon. Immediate and 3-day permeability were controlled and anastomosis times were measured.

RESULTS

Average diameter of the arteries was 0.42 mm (range 0.29-0.48 mm). Mean anastomosis duration was 19.5 min (range 15-23 min). The average number of stitches was 6. Immediate patency was 100% with a success rate of 80% at 3 days.

CONCLUSIONS

The properties of HA seem to effectively facilitate anastomoses of arteries with a diameter ≤0.5mm. HA provides comfort and promotes safety in performance of exceedingly small-scale surgery. While the results appear promising, but further studies are needed in order to determine the potential toxicity of this method on tissues.

The neck as a preferred recipient site for vascularized composite allotransplantation in the mouse

BACKGROUND

The mouse is still considered the premier model in basic immunologic and transplant-related research. However, because of its much smaller size, the mouse has proven to be a technically difficult and physiologically fragile model from a surgical standpoint. That is why only a few studies currently use mouse models in vascularized composite allotransplantation. The purpose of this study therefore was to develop a reproducible and reliable surgical technique in the mouse for future vascularized composite allotransplantation studies.

METHODS

Forty DBA/2 (H2-D) hindlimb osteomyocutanous flaps were transplanted into the right cervical region of C57BL/6 (H2-D) mice using a nonsuture cuff technique. The donor iliac artery and femoral vein were mounted with polyimide cuffs (inner diameter, 0.404 mm; wall thickness, 0.025 mm) and subsequently anastomosed to the recipient common carotid artery and external jugular vein. Immunosuppressant drugs were used postoperatively.

RESULTS

The overall success rate was 85.0 percent (34 of 40). The mortality rate was 12.5 percent (five of 40); all deaths resulted from perioperative bleeding. Only one arterial insufficiency was encountered after transplantation. The operative time was approximately 2 hours. Indefinite allograft survival (>120 days) could be achieved using a specific immunosuppressant regimen.

CONCLUSIONS

This novel mouse model allows performing vascularized composite allotransplantation with very high success and survival rates. The advantages over conventional models are multifold. A high-flow common carotid artery keeps the anastomosis patent, and diastolic suction of the heart reduces the risk of venous stasis and thrombus formation. Less destruction because of the heterotopic positioning of the hindlimb graft further reduces the associated mortality and morbidity in this fragile model.

The need for inducing tolerance in vascularized composite allotransplantation

Successful hand and face transplantation in the last decade has firmly established the field of vascularized composite allotransplantation (VCA). The experience in VCA has thus far been very similar to solid organ transplantation in terms of the morbidity associated with long-term immunosuppression. The unique immunological features of VCA such as split tolerance and resistance to chronic rejection are being investigated. Simultaneously there has been laboratory work studying tolerogenic protocols in animal VCA models. In order to optimize VCA outcomes, translational studies are needed to develop less toxic immunosuppression and possibly achieve donor-specific tolerance. This article reviews the immunology, animal models, mixed chimerism & tolerance induction in VCA and the direction of future research to enable better understanding and wider application of VCA.

Microvascular Anastomosis of Vessels Less Than 0.5 mm in Diameter: A Supermicrosurgery Training Model in Lagos, Nigeria

The development of reconstructive microsurgery has now reached the supermicrosurgery stage. However the anastomosis of vessels under 0.5 mm is still out of the comfort zone of the many microsurgeons. To confirm the technical feasibility and the reliability of this technique We relate our own experience in this regard using the free superficial inferior epigastric flap of the rat as a model for supermicrosurgery training at the Microsurgery Laboratory of the Lagos University teaching hospital. 18 of the 20 free flaps transferred survived at 1 week. Two flaps necrosed and two flaps dehisced. We believe based on our work that the average microsurgeon can become comfortable working with these vessels.