Microvascular Anastomotic Technique Research Articles

Microsurgical training through laboratory experience: A step-by-step practical guideline

BackgroundMicrosurgical laboratory training remains the mainstay to acquire, improve, and perfect surgical abilities. Microvascular anastomotic techniques are of key importance for revascularization procedures, such as in giant cerebral aneurysms, skull base complex tumours, and symptomatic ischemic cerebrovascular diseases. MethodsWe show the techniques, materials, and experience performed in a microsurgical laboratory of a neurosurgical referral center in Mexico City. ResultsWe describe the materials, non-specimen suture practices, specimen manipulation, and finally all the individual procedures we are capable to perform on live specimens. ConclusionsThe microsurgical laboratory is an indispensable tool for the acquisition of the so needed microsurgical skills in neurosurgery, having a very special emphasis in vascular neurosurgery.

Uterus transplantation in the human: a complex surgical, medical and ethical challenge

As discussed in the current issue of this journal, uterine transplant- ation in the human is becoming a real possibility, and a range of re- search and ethical criteria have been proposed to regulate its introduction (Del Priore et al., 2012). However, the need to ensure a normal pregnancy outcome will become a major clinical challenge for several reasons. First, the vascular anastomoses of the transplanted uterus will be severely tested during pregnancy. The uterus is indeed not a steady-state organ, such as the liver or kidney, but an organ re- quiring exceptional vascular plasticity to accommodate a growing fetus. During gestation, blood supply to the uterus increases from 45 to 750 ml/min, representing 25% of the cardiac output at term. Furthermore, deep placentation in humans involves transform- ation of a relative small number of spiral arteries into large vessels that provide 90% of uterine blood flow to the intervillous space of the placenta by midpregnancy. Without high-quality vascular anasto- moses that can accommodate such a dramatic increase in blood flow in a short space of time, fatal placental ischemia during pregnancy may be unavoidable. Achieving an adequate level of vascular plasticity in the transplanted uterus remains a major challenge. Autotransplantation in the porcine model using a microvascular anastomotic technique failed because of

Comparative Study of Different Combinations of Microvascular Anastomoses in a Rat Model: End-to-End, End-to-Side, and Flow-Through Anastomosis

This study aimed to compare several microvascular anastomotic techniques by patency rate using a free flap model in rats. A microsurgical transfer model of a pectoral skin flap to the cervical region was used. In experiment 1, 120 rats were divided into four groups (n = 30 in each group) depending on the type of microvascular anastomotic technique. For group 1, end-to-end anastomoses were performed for arteries and veins. For group 2, end-to-side anastomoses were performed for arteries and end-to-end anastomoses were performed for veins. For group 3, flow-through anastomoses were performed for arteries and end-to-end anastomoses were performed for veins. For group 4, end-to-end anastomoses were performed for arteries and end-to-side anastomoses were performed for veins. Flap survival was assessed on day 3 and the success rates of the four groups compared. In experiment 2 (n = 10), postoperative blood flows of end-to-end and flow-through arterial anastomoses were measured. : In experiment 1, the success rates in groups 1, 2, 3, and 4 were 76.7, 83.3, 100, and 83.3 percent, respectively. Differences between group 3 and the other groups were statistically significant. In experiment 2, the blood flow of flow-through arterial anastomosis (1.8 ml/minute) was much higher than that of end-to-end anastomosis (0.18 ml/minute). : Flow-through arterial anastomosis presented a higher blood flow through the anastomotic site, resulting in a higher success rate than conventional anastomoses. In veins, end-to-side anastomosis was equivalent to end-to-end anastomosis even though the diameter of the donor vein was larger than the recipient vein.

A New Combined “Interrupted-Continuous” Microvascular Anastomotic Technique. Experimental Study and Clinical Application

A new combined interrupted-continuous microvascular anastomotic technique is introduced, using four interrupted stay stitches and continuous suturing in between. Its efficacy is compared with the simple interrupted and continuous techniques. Microanastomoses were performed in the femoral artery and vein of rats. The patency, anastomosis time, and blood loss from the suture line of all anastomoses were recorded. Also, the sites of all anastomoses were harvested and histologically examined for lumen stenosis, media regeneration, and endothelial lining. Experimentation findings showed 100% patency rate in all groups. The combined and the continuous techniques were significantly faster and watertight compared with the simple interrupted. The only difference in pathology findings was the development of significant lumen stenosis in vein anastomoses performed with the continuous technique, compared with the other two techniques. The combined technique was clinically used in 16 free flap transfers and ensured 100% patency in all arterial and vein anastomoses, as well as survival of all flaps. In conclusion, the combined technique was found to be fast and easy to perform and ensured the same patency rate as the simple interrupted and continuous techniques. It also diminished the lumen stenosis effect of the continuous technique in vein anastomoses. Therefore, we suggest its use in both experimental studies and clinical cases.

Challenging Alexis Carrel: a study in alternate microvascular techniques

Introduction: Alexis Carrel pioneered the full-thickness triangulated vascular repair technique, which led to a Nobel Prize in 1912. However, microvascular anastomotic techniques that do not violate the intima, such as the VCS microclip repair and partial-thickness suturing, limit trauma to the intima, thus minimizing the potential for thrombosis. Our study compares such techniques with the standard full thickness-anastomotic repair.Methods: Thirty-two end-to-end anastomotic repairs were performed in rat femoral arteries 1 mm or less in diameter. Group I: thirteen full-thickness repairs were completed using 10-0 nylon on a BV75 μm needle. Nineteen extraluminal repairs were performed using either a partial thickness technique with an 11−0 nylon BV50 μm needle (Group II, n=12) or VCS nonpenetrating clip (Group III, n=7). Casted samples, injected with methylmethacrylate, were harvested at 1 and 3 weeks for histopathological evaluation. The presence of thrombosis, inflammation, endothelialization, angiogenesis and intimal hyperplasia were described for each repair.Results: Statistical analysis revealed no difference between the intraluminal and extraluminal techniques. Patency rates were similar between both groups: 92% (12/13) for Group I and 94% (17/18) for the extraluminal Groups II and III combined. One-hundred per cent of partial thickness suture repairs were patent. Histology revealed localized inflammation to the adventitia and media, as well as endothelialization at 1 week for anastomoses in Groups II and III. The intima of Group I demonstrated proliferative characteristics in contrast to the extraluminal groups, where secretory myofibroblasts were prevalent. The anastomotic microcirculation did not originate from the repaired artery in any of the groups.Conclusion: Patency rates with end-to-end anastomotic repairs using a partial thickness technique are comparable to the standard full-thickness technique. Repairs that do not include the intima revealed focal inflammatory responses to the outer layers and more rapid endothelialization, while neighboring vessels perfuse the healing anastomosis.

Reconstruction Of The Pharynx And Cervical Esophagus Using Free Jejunal Transfer

Although FJT has been perceived as unreliable, current FJT survival rates of 94% or greater, FJT salvage rates of up to 100%, and perioperative mortality of 6% or less demonstrate that FJT is a safe, reliable, one-stage method of reconstructing partial and circumferential pharyngoesophageal defects. FJT is associated with some morbidity; however, the procedure is well tolerated, and swallowing function is restored in 80% or more of patients within an average of 9 to 12 days after surgery. The success of the technique requires careful attention to details, such as designing the flap to avoid vein grafts, selecting large recipient vessels with high blood flow, careful in setting of the flap, meticulous microvascular anastomotic technique, close postoperative monitoring, and early, aggressive treatment of infection. If FJT failure should occur, a repeat FJT should be performed in the immediate postoperative period to increase the possibility of salvage and to decrease the risk of infection and mortality.

The de-endothelialized rat carotid arterial graft: A versatile experimental model for the investigation of arterial thrombosis

A novel model of arterial thrombosis was developed. A mechanical endothelium-denuding injury was created (using a scalpel blade) on harvested, freezer-stored rat carotid arteries. Vessel length of 5 mm. were grafted into the femoral arteries of recipient SpragueDawley rats using microvascular anastomotic technique. Patency rates in untreated animals were compared with those in animals receiving systemic aspirin or heparin. The control group patency after 2 hours of flow was 15%, while grafts in aspirin- and heparin-treated animals achieved 35% and 95% patency rates, respectively. Uninjured non-frozen carotid grafts in untreated animals yielded a 95% patency rate, while frozen grafts achieved an 80% patency. Therapeutic levels of aspirin, heparin, and urokinase were confirmed through tail bleeding and whole blood clotting tests, as well as platelet aggregation studies and scanning electron microscopy of the graft lumenal surfaces. A long-term series using syngeneic grafts placed in recipients (Lewis-to-Lewis) and employing systemic heparinization demonstrated maintenance of patency for 4 weeks. Scanning electron microscopy revealed good re-endothelialization, well advanced by one week. Histology confirmed the regrowth of endothelial cells, but showed sparse cellular repopulation of medial and adventitial layers. The mechanical injury model was compared to enzymatic deendothelialization (using trypsin or collagenase), for which patency rates were similar (10% and 0%, respectively). Trypsin de-endothelialized vessels were tested in vitro for the amount of active trypsin remaining bound to the lumenal surface; no detectable activity was found when trypsin inhibitor was applied following trypsin treatment. The versatility of allowing both in vitro evaluation and in vivo patency assessment demonstrates the uniqueness and value of this new model, offering an avenue toward more direct investigations of surface-mediated thrombotic processes.

The effect of venous flow alterations upon patency of rat femoral vein anastomoses.

The rat femoral vein has become a standard model for laboratory training in microvascular anastomotic technique as well as for research investigations into factors affecting venous patency. This study examined the short-term patency (1 and 7 days) of rat vein anastomoses. The influences upon patency of epigastric flap creation and distal femoral vessel ligation (epigastric flow only) were explored. In a separate experiment, blood flow from the femoral vein was determined through catheter collection of venous efflux; the influences of island epigastric flap creation and distal femoral ligation on flow rates were explored. It was found that 82% of basic femoral vein anastomoses were patent at one day, while 100% of anastomoses associated with an epigastric flap and ligated/transected distal femoral vessel circulation (creating a low-tension anastomosis) were patent (P less than 0.01). With distal femoral vessel ligation and no transection (normal tension at the repair), anastomoses were patent in 90% of the veins when an epigastric flap was also raised, and in 60% when a flap was not created. When a flap was raised without disturbing the distal femoral circulation, vein patency was 75% at one day. When the vein anastomosis was performed with distal femoral vein ligation, the patency rate was 50%. All veins patent at 1 day were also patent at 7 days post-op; 96% of veins clotted at 1 day were found to be patent at 7 days. The venous efflux was not found to vary significantly when an epigastric flap was raised.(ABSTRACT TRUNCATED AT 250 WORDS)

The Efficacy of Absorbable Suture for Microvascular Anastomoses

Although microvascular anastomoses are routinely performed with nonabsorbable sutures, a foreign body reaction can be stimulated that acts as a nidus for inflammation, infection, and possible thrombosis. Absorbable sutures should be able to diminish this reaction. There are sparse data describing the use of absorbable sutures for both arterial and venous anastomoses. This investigation compares standard microvascular anastomotic technique using nonabsorbable 10-0 sutures (nylon) with absorbable 10-0 sutures (polyglactin 910), using a previously reported tubed superficial epigastric flap model in rats. Patency rates and histologic responses are compared at intervals of 3 days and 1, 2, 8 and 12 weeks postoperatively. Arterial and venous patency rates were similar for both materials (overall nonabsorbable, 85.9%; overall absorbable, 84.4%). A somewhat increased inflammatory response was noted in the arterial absorbable group at 1 week and in both the venous and arterial nonabsorbable groups at 8 and 12 weeks postoperatively. The later finding most probably represents the continued presence of the nylon sutures. The incidence of intraluminal thrombosis was greater for nonabsorbable suture, occurring in two arterial and four venous anastomoses, compared with only one absorbable suture venous anastomosis. We conclude that nonabsorbable suture is as efficacious as standard absorbable material in both arterial and venous microanastomoses with the potential benefit of diminished foreign body reaction.

Evaluation of the Unilink Microvascular Anastomotic Device in the Dog

This experimental study reports the evaluation of a mechanical, non-suture technique for the repair of small blood vessels under the operating microscope. The method uses the Unilink implantable pinned rings on which the vessel ends are everted 90 degrees and impaled on small pins. An instrument approximates the rings and completes the anastomosis. The device was used for the end-to-end anastomosis of 80 vessels in ten beagle dogs. Both arteries (ulnar and saphenous) and veins (cephalic and saphenous) were included in the study. Vessels were assessed for patency and harvested for histologic examination and scanning electron microscopy at 4-, 16-, and 32-week implantation times. Both longitudinal and cross sections were stained using hematoxylin and eosin, Verhoeff-Van Gieson techniques for elastin, and a modified Masson's trichrome for muscle and collagen, and examined under light microscopy. Scanning electron microscopy (SEM) was completed on longitudinally bisected anastomoses. Patency rates, histology, and SEM at all implantation times of the mechanical anastomoses compared favorably with experimental investigations of suturing techniques that have appeared in the literature. This microvascular anastomotic technique provided a rapid, safe, and efficacious method for the end-to-end repair of severed peripheral arteries and veins in the dog model.

Treatment of intractable lymphangioma by microvascular anastomotic free omental transplantation

Three cases of massive recurrent lymphangioma of the left foot, left axialla and right leg in patients aged 15–17 years were successfully treated by free omental transplantation using microvascular anastomosis. After lymphangioma excision, the omentum was removed with the right gastroepiploic vessels and transferred to the operative surface. The omental vessels were anastomosed to the regional vessels by microvascular anastomotic technique. The skin was closed primarily or by split-skin graft. The transferred omentum acted as a fat pad for the operative surface, served as a base for the skin graft to absorb lymphatic fluid, and prevented recurrence. The longest postoperative follow-up time was 5 years. All three cases showed good wound healing, and there was no lymphorrhea, infection, or recurrence. This new method is effective in the treatment of massive recurrent lymphangioma unresponsive to conventional means.

Evaluation of Anastomotic Techniques in the Experimental Transfer of Free Skin Flaps

Vascularized groin flaps were transferred to the contralateral side by various microvascular anastomotic techniques. There was no statistical difference between the results of end-to-end and end-to-side anastomoses, when the same sized vessels were compared. However, significant differences existed when vessels smaller than 0.5 mm in diameter were anastomosed.

Microvascular Free Tissue Transfer at Chittagong Medical College Hospital - A Milestone

Introduction: A defect in any part of the body involving extensive soft tissue loss adversely affects the functional ability. With the advent of microvascular free tissue transfer in the reconstruction of large defects, the problem is going to be solved. However, studies are still going on about the different aspects of its success and failure. The present study is one such step to share our early experience.Methods: The study was carried out in the Department of Plastic Surgery, Chittagong Medical College Hospital from August 2009 to April 2010. We reviewed the operative experiences of free tissue transfer on 5 cases. Standard microvascular anastomotic techniques as well as peroperative & postoperative heparinization were maintained in all the cases. Follow up results were evaluated at varying periods following standard protocol.Results: Of the 5 cases reconstructed, 4(80%) had lesions in the maxillofacial region and 1(20%) in the ankle region. In terms of diseases they suffered, 3(60%) had squamous cell carcinoma and 2(40%) sustained mechanical injury. The outcome of treatment demonstrates that 3(60%) cases recovered uneventfully, one developed slight loss of sensation on the left thumb (20%) and another one failed to recover (20%).Conclusion: In this study successful microvascular free tissue transfer was possible in 80% cases. With the increase in experience we can expect increased success rate as well.DOI: http://dx.doi.org/10.3329/bdjps.v1i1.6485Bangladesh Journal of Plastic Surgery (2010) Vol. 1 (1) pp.3-8