The pathogenesis of vascular thrombosis and its impact in microvascular surgery

Safe and effective thrombolysis in free flap salvage: Intra-arterial urokinase infusion

Despite the high success rate in reconstruction using free tissue transfer, flap failure is often caused by microvascular thrombosis. In a small percentage of cases with complete flap loss, a salvage procedure is performed. In the present study, the effectiveness of intra-arterial urokinase infusion through the free flap tissue was investigated to develop a protocol to prevent thrombotic failure. The retrospective study evaluated the medical records of patients who underwent salvage procedure with intra-arterial urokinase infusion after reconstruction with free flap transfer between January 2013 and July 2019. Thrombolysis with urokinase infusion was administered as salvage treatment for patients who experienced flap compromise more than 24 hours after free flap surgery. Because of an external venous drainage through the resected vein, 100,000 IU of urokinase was infused into the arterial pedicle only into the flap circulation. A total of 16 patients was included in the present study. The mean time to re-exploration was 45.4 hours (range: 24-88 hours), and the mean quantity of infused urokinase was 69,688 IU (range: 30,000-100,000 IU). 5 cases presented with both arterial and venous thrombosis, while 10 cases had only venous thrombosis and 1 case had only arterial thrombosis; in a study of 16 patients undergoing flap surgery, 11 flaps were found to have survived completely, while 2 flaps experienced transient partial necrosis and 3 were lost despite salvage efforts. In other word, 81.3% (13 of 16) of flaps survived. Systemic complications, including gastrointestinal bleeding, hematemesis, and hemorrhagic stroke, were not observed. The free flap can be effectively and safely salvaged without systemic hemorrhagic complications using high-dose intra-arterial urokinase infusion within a short period of time without systemic circulation, even in delayed salvage cases. Urokinase infusion results in successful salvage and low rate of fat necrosis.

Free Flap Reconstruction of the Head and Neck Region: A Series of 127 Flaps Performed by Otolaryngologists

Objective:

To determine flap success rate and complications in patients who underwent microvascular free tissue reconstruction after major head and neck ablative surgery and to report the improvement in the results.

Methods:

Medical records of 124 patients who were operated on in 2012 to 2019 were retrospectively reviewed. Indications for different free flap types, success rates and re-exploration rates, donor site morbidities, and reasons for flap loss were analyzed. Patients were divided into two groups to identify the effects of the anticoagulant and the antiaggregant treatments on postoperative results.

Results:

There were 127 flaps in 124 patients, including two different free flaps each in three patients that were harvested and used in the same surgical session. Of the total 127 flaps, 82 (64.6%) were radial forearm flaps, 39 (30.7%) were fibula flaps, and 6 (4.7) were rectus abdominis flaps. Four patients were re-explored for flap perfusion problems, and 18 patients were re-explored for hematoma drainage (n=22/124, %17.3). The rate of hematoma and re-exploration was higher in patients who received anticoagulant and antiaggregant treatments synchronously (p=0.02). Three flaps were lost, and the overall success rate was 97.6%. Two patients died from perioperative complications. No major complications were observed at the donor site; minor complications were observed in 30 patients.

Conclusion:

The success rate for the 127 flaps in 124 patients were found comparable to those reported in the literature. These results show that successful outcomes can be achieved with experience and a head and neck team dedicated to improving the results in microsurgical reconstruction, and flap failure rarely occurs if perioperative care of the patients is given meticulously.

Utilization of microvascular couplers in salvage arterial anastomosis in head and neck free flap surgery: Case series and literature review

BACKGROUND

In microvascular reconstruction of ablative oncologic defects, coupler devices have traditionally been used for venous anastomosis, whereas the arterial anastomosis is hand-sewn. In the setting of repeated intraoperative arterial anastomotic thrombosis, a coupler device may be of use in reducing the risk of rethrombosis.

METHODS

Two patients were seen with advanced stage head and neck cancer and underwent oncologic resection. During microvascular reconstruction, a clot at the arterial anastomosis was encountered in both cases.

RESULTS

After starting therapeutic anticoagulation and attempting unsuccessful suture reanastomosis, coupler devices were used for arterial anastomosis, resulting in viable free-tissue transfer.

CONCLUSIONS

Although traditionally used for venous anastomosis, coupler devices may serve a purpose in the salvage setting when facing repeated intraoperative arterial thrombosis.

Timing of Heparin Administration Modulates Arterial Occlusive Thrombotic Response in Rats

Background: The timing for initiation of effective antithrombotic therapy relative to the onset of arterial thrombosis may influence outcomes. This report investigates the hypothesis that early administration of heparin anticoagulation relative to the onset of thrombotic occlusion will effect a reduction in occlusion. Methods: A standard rat model of experimental thrombosis induction was used, injuring the carotid artery exposure with FeCl₃-saturated filter paper, followed by flow monitoring for onset of occlusion and subsequent embolization events. Intravenous heparin administration (200 units/mL) was timed relative to the initiation of injury or onset of near occlusion, compared with controls (no heparin administration). Results: No occlusion was found for delivery of heparin 5 min prior to thrombus induction, whereas all vessels occluded without heparin. Unstable (embolic) thrombi were seen with heparin given at or shortly after initial occlusion. Only 9% (1/11) of the vessels had permanent occlusion when heparin was given at the time of thrombotic onset (p < 0.0001 vs. unheparinized), while 50% occluded when heparin was delayed by 5 min (p > 0.05). Conclusions: These findings provide evidence that antithrombotic therapy may need to be administered prior to the onset of anticipated loss of patency, with less effectiveness when given after occlusion has occurred.

Vein conduit for end-to-side anastomosis of a calcified vessel in lower extremity free flap reconstruction

BACKGROUND

As the microsurgical and interventional revascularization techniques are evolving, traditionally amputated limbs are now challenged to salvage. However, a calcified recipient vessel is a common but challenging problem encountered in lower extremity reconstruction.

METHODS

An end-to-side anastomosis of a vein graft (1.5-3.5 cm in length) was performed to the recipient vessel when it was difficult to clamp the recipient vessel near the defect because of the inelastic and hard vessel wall. The vascular clamp was applied to the vein graft, and the flap's pedicle was anastomosed to the vein graft.

RESULTS

A total of 18 free flaps (10 ALT cases, 4 TDAP cases, 2 PAP cases, and 2 SCIP cases) were anastomosed with a bridge vein graft to the heavily calcified recipient vessels (7 ATA cases, 3 PTA cases, 7 DPA cases, and 1 MPA case). Overall flap survival rate was 83.3%. Limb salvage rate was 93.7%, and anastomosis patency rate was 94.4% CONCLUSION: Vein conduit in an end-to-side anastomosis of severely calcified recipient vessels shows a reasonable limb salvage rate. It acts as a buffer, which makes microscopic vessel manipulation easier. If vessel calcification is the only drawback for a free flap reconstruction, then a vein graft needs to be prepared instead of an amputation. This method may extend the surgical option to more high-risk patients in lower extremity microsurgical reconstruction and increase the limb salvage rate.

Towards standardization of training and practice of reconstructive microsurgery: an evidence-based recommendation for anastomosis thrombosis prophylaxis

BACKGROUND

Despite significant improvements in survival rates, free flap failures still occur even in experienced hands and are most commonly due to arterial or venous thrombosis. In the absence of an evidence-based guideline on the prevention of thrombosis, we reviewed the literature to assess the evidence base for commonly used interventions aimed at its prevention.

METHODS

A comprehensive literature search was performed using the following keywords "free flap" and microsurgery with "pre-operative screening," "prevention of thrombosis," "ketorolac," "heparin," "low molecular weight heparin," "aspirin," "dextran," and "statins."

RESULTS

Thirteen clinical studies were included in this review. No high-level evidence is available to support any perioperative or postoperative interventions aimed at reducing the risk of flap thrombosis.

CONCLUSIONS

Higher level studies are needed to investigate the clinical use of antithrombotic medications in microsurgery; however, given the small failure rates in modern practice, these will need to be large multicenter trials in order to reach sufficient power.Level of Evidence: Level III, risk/prognostic study.

The "Rolled-Up Sleeve" Technique for Microvascular Venous Anastomosis in Head and Neck Reconstruction: Animal Study and Clinical Series

BACKGROUND

Venous anastomosis is challenging especially when encountering the thin recipient vein wall in the head and neck region. The authors developed the "rolled-up sleeve" technique to solve this scenario.

METHODS

An animal study was performed to access the safety and reliability of the "rolled-up sleeve" technique. This technique was performed in 53 consecutive patients during head and neck reconstruction.

RESULTS

In the animal study, all anastomoses were patent. Histological analysis revealed neo-endothelialization over the anastomotic site. This technique was applied to 59 recipient veins: branch of internal jugular vein (27), external jugular vein (17), superficial temporal vein (9), retromandibular vein (4), facial vein (2), and internal mammary vein (2). No venous thrombosis occurred in these clinical series.

CONCLUSIONS

The "rolled-up sleeve" technique is a useful procedure that can be performed safely to deal with thin vascular walls for venous anastomoses in head and neck reconstructions.

A new microsurgical research model using Thiel-embalmed arteries and comparison of two suture techniques

PURPOSE

To assess the utility of the Thiel arterial model in microsurgical research, we compared interrupted horizontal mattress (HM) sutures to simple interrupted (SI) sutures in human vessels.

METHODS

A microsurgical set-up using an operating microscope and Thiel-embalmed arteries was used to practice ten SI and HM anastomoses. Vessel patency, leak and stricture were evaluated using angiography, and vessel wall architecture was evaluated using light microscopy and scanning electron microscopy (SEM). The technique speed was also assessed.

RESULTS

We have successfully evaluated all outcomes. All anastomoses were patent. The stricture rate was higher with HM than with SI (60% vs. 35% surface area reduction). Three minor leaks occurred with HM sutures versus one with SI sutures. Edges were evenly everted without any intimal flaps with HM compared to SI. The anastomoses were performed faster using HM than SI sutures (7:58 min vs. 12:41 min, respectively).

CONCLUSION

This is the first study to evaluate the feasibility of a Thiel-embalmed artery model for research purposes. The HM microvascular suture is a promising technique that requires further in vivo validation.

Short-term vasculoprotective effects of imatinib mesylate on intimal hyperplasia of arterial anastomosis: An experimental study using a rabbit model

BACKGROUND

Since the beginning of the 'microvascular era', the success rates of microvascular procedures have increased to more than 90% in most series. The main reason for failure, however, is the healing of microarterial anastomosis, which is dependent on the status of endothelial cells and affects the rate of arterial thrombosis. In 80% of arterial thrombosis cases, complications are primarily observed during the first 72 h after surgery. Healing of arterial anastomosis results in intimal hyperplasia in which myofibroblasts comprise the predominant cell type. Intimal hyperplasia has been described previously as an adaptive process that occurs in response to hemodynamic stress or injuries to the vascular bed. During wound healing, fibroblasts proliferate, migrate and differentiate into myofibroblasts - a process that takes one to three days. Imatinib mesylate (ST1571-Gleevec, Novartis, Germany) is a specific platelet-derived growth factor receptor blocker that has found use as an adjunct to sirolimus in cardiovascular surgery for restenosis. However, its potential utility in preventing arterial thrombosis in microvascular surgery has not been evaluated in routine plastic surgery practice.

METHODS

Twenty-four randomly selected, male, white New Zealand rabbits were divided into six groups (A to F), and the femoral artery model was used for arterial anastomosis. Following anastomosis, groups A, B and C received phosphate-buffered saline orogastrically. In groups D, E and F, imatinib mesylate was administered via an orogastric tube twice per day at a dose of 10 mg/kg starting two days before arterial anastomosis. Following anastomosis, imatinib mesylate was administered for one, three and seven days, and the regression of intimal hyperplasia was recorded.

RESULTS

In groups administered imatinib mesylate (ie, groups D, E and F), intimal hyperplasia decreased by up to 50%, which represented a statistically significant difference. Histological analysis confirmed smooth muscle cell migration from the tunica intima to media on days 3 and 7 in groups E and F.

CONCLUSION

The present study revealed that imatinib mesylate, which was initiated as a prophylactic, systemic pretreatment and continued for seven days, gradually decreased intimal hyperplasia at the anastomosis site.

Anterograde intra-arterial urokinase injection for salvaging fibular free flap

We present a case of a 57-year-old male patient who presented with squamous cell carcinoma on his mouth floor with cervical and mandibular metastases. Wide glossectomy with intergonial mandibular ostectomy, and sequential reconstruction using fibular osteomyocutaneous free flap were planned. When the anastomosis between the peroneal artery of the fibular free flap and the right lingual artery was performed, no venous flow was observed at the vena comitans. Then re-anastomosis followed by topical application of papaverine and lidocaine was attempted. However, the blood supply was not recovered. Warm saline irrigation over 30 minutes was also useless. Microvascular thromboses of donor vessels were clinically suspected, so a solution of 100,000 units of urokinase was infused once through a 26-gauge angiocatheter inserted into the recipient artery just at the arterial anastomotic site, until the solution gushed out through the flap vena comitans. Immediately after the application of urokinase, arterial flow and venous return were restored. There were no complications during the follow-up period of 11 months. We believe that vibrating injuries from the reciprocating saw during osteotomies and flap insetting might be the cause of microvascular thromboses. The use of urokinase may provide a viable option for the treatment of suspicious intraoperative arterial thrombosis.

The intrinsic transit time of free microvascular flaps: clinical and prognostic implications

BACKGROUND

Microscope-integrated indocyanine green near-infrared videoangiography (ICGA) is a new method for the intraoperative assessment of vascular flow through microvascular anastomoses. The intrinsic transit time (ITT) describes the time period from the dye appears at the arterial anastomosis (t(1)) till it reaches the suture line of the venous anastomosis (t(2)). As the transit time reflects blood flow velocity within the flap, prolonged ITT might correlate with low blood flow and a higher rate of postoperative thrombosis. We performed a clinical trial evaluating the association between intraoperative free flap transit time and early anastomotic complications in elective microsurgery.

METHODS

One hundred consecutive patients undergoing elective microsurgical procedures underwent intraoperative ICG angiography (ICGA). In patients with anastomotic patency, angiograms were retrospectively reviewed and the intrinsic transit time was calculated. Postoperative outcome was registered and compared with the ITT. End points included early reexploration surgery and flap loss within the first 24 hours after surgery.

RESULTS

Fourteen patients were excluded from the study due to technical anastomotic failure. The overall flap failure rate was 6% (5/86); the incidence of early re-exploration surgery was 10% (9/86). With a median of 31 seconds patients with an uneventful postoperative course showed significantly shorter ITTs than patients with flap loss or early postoperative reexploration (median: >120 seconds). An optimal cut-off value of ITT > 50 seconds was determined to be strongestly associated with a significantly increased risk of at least one positive end point.

CONCLUSIONS

This study demonstrates a significant predictive value of the intrinsic flap transit time for the development of flap compromise and early re-exploration surgery.

Microsurgical complications in the upper extremity

Although many advances have been made in microsurgery, it is not without complications. As microsurgeons continue to make advances in technology, technique, and applications that expand the utility of this field to more and more patients, they must be prepared to deal with the complications related to donor and recipient sites and the medical comorbidity that accompanies these large endeavors in the pre-, post-, and intraoperative periods.

Principles of Skull Base Reconstruction After Ablative Head and Neck Cancer Surgery

“Resection of malignancies of the skull base can result in significant functional and cosmetic morbidity as well as mortality. Reconstructive efforts provide not only functional and cosmetic rehabilitation, but also allow for the avoidance of potentially disastrous complications such as cerebrospinal fluid leak or meningitis. The optimal reconstruction is determined both by a patient based approach and a defect based approach. Skull base defects can be addressed by the separate components of the craniofacial skeleton in which they involve, and therefore the individual reconstructive issues which must be addressed. In this article, we describe an approach to skull base reconstruction and the technical aspects of the available reconstructive options.

Strategies for avoiding complications with vascularized bone flaps in head and neck microvascular reconstruction

Effective osseous reconstruction of the head and neck after congenital, traumatic, and particularly ablative oncologic procedures is a relatively recent innovation. Whereas pioneers led with individual donor sites, it is only in the past 20 years that most centers have developed teams comfortable with use of the four common donor sites for free flaps: iliac crest, fibula, radius, and scapula. Calvarium, though much less frequently used, is a useful donor site for specific reconstructive challenges. Less commonly used sites such as femur, humerus, and rib have not proved universally reliable. This article aims to illustrate some refinements and pitfalls in vascularized osseous reconstruction of the head and neck using the well-recognized flaps, including calvarium, in a variety of pathologic conditions, recipient-site defects, and comorbidities. Strategies for error avoidance will be emphasized. The authors hope that this will support the concept of a reconstructive "toolbox" for this complex area.

Desirudin reduces the rate of microvenous thrombosis in a rat model

OBJECTIVES

In an effort to evaluate pharmacologic agents for optimal anticoagulant prophylaxis in patients undergoing free tissue transfer, we evaluated the efficacy of desirudin (Canyon Pharmaceuticals, Hunt Valley, MD), a recombinant hirudin that acts as a direct thrombin inhibitor, using a rat model of microvenous thrombosis.

STUDY DESIGN

Randomized, blinded study using an in vivo rat model of microvenous failure.

METHODS

Thirty-two rats received either desirudin or saline in a randomized, blinded fashion 30 minutes prior to performance of a standardized thrombogenic procedure on rat femoral veins. Bleeding time, vessel patency, and presence of clot within the anastomosis were subsequently assessed. Appropriate statistical analyses were then performed.

RESULTS

There was a significant increase in vessel patency in rats treated preoperatively with desirudin compared to controls receiving saline (96.9% vs. 53.1%, P < .001). In evaluating patent vessels for non-occluding clot, 41.2% of control rats had non-obstructive clot at the site of anastomosis, versus 3.2% of rats treated with desirudin (P = .002). Bleeding times were longer in desirudin-treated rats than those that received saline (7.17 +/- 3 minutes vs. 5.15 +/- 1.2 minutes, P = .027).

CONCLUSIONS

The use of preoperative desirudin increases the rate of microvascular anastomotic patency, decreases the occurrence of non-occluding clot, and increases bleeding time in an in vivo rat model, indicating potential efficacy in patients undergoing microvascular free tissue transfer.

Free Tissue Transfer to the Lower Extremity Distal to the Zone of Injury: Indications and Outcomes over a 25-Year Experience

BACKGROUND

Microvascular free flap anastomoses performed for lower extremity reconstruction are traditionally proximal to the zone of injury. The authors assessed the feasibility and outcomes of microvascular free flaps with anastomoses performed distal to the zone of injury.

METHODS

The authors retrospectively reviewed all microvascular free flaps performed at their institution over the past 10 years for lower extremity reconstruction and compared this group with their previously published experience (January of 1979 through August of 1995). Between September of 1995 and May of 2005, 119 flap procedures were performed for lower extremity reconstruction. Twenty-eight flaps (24 percent) were anastomosed distal to the zone of injury and 87 (76 percent) were anastomosed proximally. There were insufficient data on the location of the anastomosis for four free flaps (all successful).

RESULTS

Twenty-seven of 28 distal microvascular free flaps were successful (96 percent); two (7 percent) required emergent postoperative reexploration of the anastomosis. Of the 87 proximal flaps, 79 (91 percent) were successful and eight (9 percent) failed. There was no statistically significant difference in the success rate of microvascular free flaps between the proximal and distal anastomosis groups (p = 0.30, Fisher's exact test). Combined with the data from the authors' previous series (January of 1979 to August of 1995), there were 63 free flaps with anastomosis performed distal to the zone of injury; 61 (97 percent) were successful.

CONCLUSION

The authors' extensive 25-year experience with lower extremity reconstruction demonstrates that in appropriately selected patients, free tissue transfer to recipient vessels distal to the zone of injury is reliable and in certain cases preferable.

Clopidogrel (Plavix) reduces the rate of thrombosis in the rat tuck model for microvenous anastomosis

OBJECTIVE

To evaluate the effect of clopidogrel on the rate of thrombosis in a rat model for venous microvascular failure.

STUDY DESIGN AND SETTING

Forty rats were treated with clopidogrel or saline control via gastric gavage in a randomized, blinded fashion. After allowing for absorption and activation, each femoral vein was isolated and a venous "tuck" procedure was performed. The bleeding time and vessel patency were subsequently evaluated.

RESULTS

The rate of vessel thrombosis was decreased in the clopidogrel-treated group compared to controls (7.9% vs 31.4%, P < 0.025). The bleeding time was longer in the clopidogrel-treated group compared to controls (250 +/- 100 seconds vs 173 +/- 59 seconds, P < 0.015).

CONCLUSION

Clopidogrel decreased the rate of thrombosis in the rat model for venous microvascular failure.

SIGNIFICANCE

The use of clopidogrel may reduce the rate of venous thrombosis after free tissue transfer and may be indicated in select patients.

Aplicação da microcirurgia no serviço de cirurgia plástica da universidade federal da bahia: análise dos resultados e complicações

OBJETIVO: O estudo pretende relatar a experiência inicial de um serviço de cirurgia plástica ao implantar um grupo de microcirurgia, analisando as complicações e resultados da casuística. MÉTODO: No período de fevereiro de 2003 a junho de 2004, foram realizados 20 procedimentos de microcirurgia reconstrutiva variando em reconstruções de cabeça e pescoço, mama e membros inferiores. As complicações foram divididas em imediatas (intra-operatórias), recentes (até 21dias) e tardias (após 21dias). Foram analisadas complicações relacionadas às reconstruções, divididas em menores (perda parcial do retalho e/ou satisfação parcial do plano pré-operatório) e maiores (perda total do retalho e/ou não satisfação do plano pré-operatório). Em relação às áreas doadoras, foram divididas em menores (com necessidade de re-intervenção cirúrgica) e maiores (deformidade não satisfatória ao cirurgião ou não aceitável ao paciente). Os resultados foram classificados como bons, satisfatórios ou ruins. RESULTADOS: Quinze retalhos sobreviveram (73,68% de sucesso) e em cinco houve perda total. Foram encontradas, em relação à reconstrução, 21,05% de complicações imediatas, 45% de recentes e nenhuma tardia. Em relação à área doadora, foram observadas apenas complicações recentes (35%). Os resultados (reconstrução) foram classificados em bons (55%), satisfatórios (20%) e ruins (25%). Os resultados (áreas doadoras) foram bons (65%), satisfatórios (35%) e ruins (0%). CONCLUSÃO: A incidência aumentada de necrose total do retalho talvez se deva à seleção de pacientes. Observou-se uma grande dificuldade na implantação de um serviço de microcirurgia. Os resultados, bons e satisfatórios em 75% das reconstruções e em 100% das áreas doadoras favoreceram a sedimentação e credibilidade do procedimento.

Use of continuous horizontal mattress suture techniques in microsurgery: an experimental study in rats

PURPOSE

The purpose of this study was to determine whether the continuous horizontal mattress suture technique can replace the continuous simple suture technique and to compare the results with other microvascular suture procedures.

METHODS

Sixty-four femoral arteries of 32 Sprague-Dawley rats were used in this study. The animals were divided equally into 4 groups with 16 anastomoses in each group. The arteries (0.8-1.0 mm diameter) were anastomosed by using the continuous horizontal mattress suture technique in group I, interrupted horizontal mattress suture technique in group II, simple interrupted suture technique in group III, and simple continuous suture technique in group IV. At the end of the anastomosis time, leakage, and patency were assessed and graded in all groups. On the 14th day after surgery the rats were killed and 5 patent specimens from each group were examined under light microscopy for histology. One specimen from each group was prepared for scanning of the endothelial surface under electron scanning microscopy.

RESULTS

Group I anastomoses were performed the most quickly. Groups I and III anastomoses had 100% patency rates. Under light microscopy the edge eversion was apparent consistently and under electron microscopy all endothelial surfaces were intact and no suture material was seen in groups I and II. In group III some suture material was covered by endothelial cells and lumen surfaces were torn; endothelization also was rough compared with groups I and II. In group IV suture material was seen in the lumen because of a loose suture knot. The endothelium also was not regular.

CONCLUSIONS

The horizontal mattress suturing technique is the only technique in which the suture material never contacts the lumen. Continuous horizontal mattress suture technique is superior to the other microvascular procedures and is the safest and fastest procedure for microvascular anastomosis in rats.

Complications of free flap transfers for head and neck reconstruction following cancer resection

The reported success rate of microvascular free flap reconstruction ranges between 95% and 97%. However when complications occur, they must be identified early and managed efficiently because there is a narrow window of opportunity to salvage potential flap failure. While technical advances in instrumentation and magnification have improved overall success rates, the rare complication may prove devastating for the patient, his/her hospital stay, and the optimum rehabilitation. Complications of microvascular free tissue transfer may occur at the recipient site or at the donor site. Complications occurring at the recipient site are largely a result of vessel thrombosis while complications occurring at the donor site may result from many causes, ranging from infection to those related to the harvesting of the flap. Irrespective of the site of the complication, it is essential that complications be recognized and addressed early in their course to prevent or minimize devastating consequences.

Pharmacological thrombolysis: One more weapon for free-flap salvage

Despite the high success rate of free-tissue transfer, thrombosis still complicates 5-30% of cases. Meticoulous technique, careful vessel selection, and pharmacological prophylaxis are not always enough to avoid thrombosis. Early diagnosis and reintervention provide the only way to salvage a thrombosed free flap, in case of either arterial or venous thrombosis. When kinking, torsion, or external compression of the pedicle are ruled out, and thrombectomy and redo of the anastomosis are unsuccessful, the last resort to save the flap is thrombolytic therapy. The authors present their experience with the salvage of two otherwise lost flaps by means of urokinase thrombolysis through direct intra-arterial injection with the vein left open to avoid systemic diffusion of the drug, and give technical tips to improve drug delivery to the flap. Pharmacological thrombolysis is an additional and effective weapon to resolve thrombosis, if properly used, to be considered by every reconstructive microsurgeon.

Salvage of free flaps after venous thrombosis: Case report

Venous thrombosis of a free flap is a serious complication in microsurgery. Several agents with the ability to dissolve an occluding thrombus exist. Recombinant tissue plasminogen activator (rt-PA) seems the most effective. We present our experience with a procedure that was successful in elimination of the occluding thrombus in two patients.

Coronary end-to-side sleeve anastomosis using adhesive in off-pump bypass grafting in the pig

BACKGROUND

In the exploration of facilitated coronary anastomosis strategies, we assessed a new octylcyanoacrylate adhesive in combination with a modified end-to-side sleeve anastomosis in off-pump bypass grafting in the pig.

METHODS

Sleeve-adhesive anastomoses (n = 20) were evaluated intraoperatively, at 3 days (n = 4), and at 5 weeks (n = 16) in an off-pump, low (< or = 15 mL/min; n = 10) and high flow (approximately 60 mL/min; n = 10) porcine bypass model. All anastomoses were examined by flow measurement, angiography, and histology.

RESULTS

Anastomosis construction took 8.5 minutes (6.7 to 10.2 minutes; median [15th to 85th percentile]). At 5 weeks, all anastomoses were fully patent (FitzGibbon grade A). The adhesive did not cause impaired vessel wall healing, but was surrounded by a focal acute and limited chronic (foreign body giant cells occasionally seen) inflammatory reaction at the adventitial application site.

CONCLUSIONS

Octyl-cyanoacrylate tissue adhesive combined with end-to-side internal mammary to coronary artery sleeve anastomosis construction proved to be feasible, even in low bypass graft flow conditions (< or = 15 mL/min; prothrombotic milieu) in the pig and deserves interest in exploration of facilitated anastomosis strategies in coronary artery bypass grafting.

Pharmacological salvage of a combined distal bypass and free flap with catheter-directed thrombolysis

With recent improvements in microvascular techniques, the use of combined distal bypass and free-flap transfer has been advocated for salvaging the critically ischaemic limb in extreme conditions. Distal bypass, however, carries an inherent risk of graft failure due to thrombosis, and this may threaten the viability of the free flap and, indeed, the lower limb. We present the case of a 66-year-old man with acute-on-chronic ischaemia of his left leg and rectus abdominis free flap. Despite a prolonged ischaemic time of 72 h, both were successfully salvaged using catheter-directed recombinant tissue plasminogen activator. This is previously unreported in the literature.

Unconventional vessel wall apposition in off-pump porcine coronary artery bypass grafting: low versus high graft flow

OBJECTIVE

Facilitated coronary anastomosis techniques may involve unconventional vessel wall apposition in contrast to standard intima-intima apposition. We assessed the patency, anastomotic thrombus formation, and intimal hyperplasia of unconventional intima-adventitia apposition versus conventional suturing techniques in beating heart coronary bypass grafting under low versus high graft flow conditions.

METHODS

The intima-adventitia (n = 28) and conventional anastomoses (n = 28) were evaluated intraoperatively (n = 56), at 4 hours (n = 20), and at 5 weeks (n = 36) in a new off-pump low-flow (n = 28) and high-flow (n = 28) porcine bypass model (< or = 15 mL/min and about 60 mL/min, respectively). The anastomoses were assigned to the animals by means of randomized stratification and examined by means of flow measurements, angiography, and histology.

RESULTS

Mean graft flows in intima-adventitia and in conventional anastomoses were similar (P =.709). All but 1 of 56 anastomoses (low flow conventional) were fully patent at the time of death. At 4 hours, only small platelet depositions were found at the exposed media and adventitia in the unconventional anastomoses. At 5 weeks, little streamlining intimal hyperplasia was found, which was comparable between the anastomoses (P =.600).

CONCLUSIONS

In low-flow conditions (< or = 15 mL/min) unconventional intima-adventitia apposition was not detrimental to the internal thoracic-coronary artery anastomosis in the pig. This finding may expand design strategies of facilitated coronary artery bypass anastomosis techniques.

Ischemia/reperfusion injury in microvascular surgery

Ischemia/reperfusion injury is often the final and irreversible factor causing flap failure in microvascular surgery for head and neck defects. This paper begins with a detailed review of flap physiology and ischemia/reperfusion injury at the cellular level. Subsequently, the pharmacotherapeutic agents used clinically and experimentally to avoid or reverse ischemia/reperfusion injury are discussed. The goal of this review is to provide a framework for understanding the expanding body of literature relevant to ischemia/reperfusion injury in microvascular surgery.