The complicated role of venous drainage on the survival of arterialized venous flaps

The clinical application of arterialized venous flaps in repairing large area of soft tissue defects of extremities

BACKGROUND

The reconstruction of microsurgery emphasizes the low morbidity of donor sites. The arterialized venous flaps (AVFs) are tissue flaps harvested without conventional vascular pedicles. However, reports of high necrosis rates and poor understanding of physiology hindered the application of many surgeons in clinical practice. Recently, experimental and clinical studies have demonstrated the feasibility and relative reliability of various AVF techniques. This study aims to report the clinical results of the arterialized venous free flaps in reconstructing soft tissue defects of limbs and propose methods to improve flap perfusion, extending the indications for using the flaps based on the authors' clinical experiences.

METHODS

We retrospectively reviewed the records of 16 patients that underwent arterialized venous free flaps for limb wound reconstruction from January 2019 to June 2021. Following the venous network on the calf's tibial side, large venous flaps can be designed.

RESULTS

Of the 16 cases, 14 (87.50%) cases (including 8 cases significantly congested with tension blisters) showed complete survival, and 2 (12.5%) cases, which had only one vein performed anastomosis of the efferent vein according to the vascularity of the recipient bed, showed partial necrosis. In all cases, no infection or other specific complications occurred in the donor areas.

CONCLUSION

The rate of congestion and necrosis of arterialized venous flaps is still challenging, but it will be suitable for large soft tissue defects of limbs in the future.

The arterialised saphenous venous flow-through flap for managing the radial forearm free flap donor site

BACKGROUND

The radial forearm fasciocutaneous flap (RFFF) is a workhorse flap, however concerns with donor site morbidity include tendon exposure, delayed wound healing, impaired sensitivity, and poor cosmesis, have seen it fall out of favor. We present a method of using an arterialised saphenous flow through flap to reconstruct the RFFF donor site.

METHOD

A cohort study of six patients (five male, one female; mean age 59 [range 19-90]) who had their RFFF donor site reconstructed with an arterialised saphenous flow through flap is presented. The use of multiple peripheral efferent venous anastomoses, flap rotation 180 degrees prior to inset, and the ligation of intra-flap connecting veins were three modifications employed. Primary outcomes include complication rates. Secondary outcomes were patient reported outcome measures via the Michigan Hand Outcomes Questionnaire, and patency and flow through the flap.

RESULTS

In all six cases, there was flap survival. RFFF dimensions ranging from lengths of 6-15 cm (mean 11.5 cm) and widths of 4-6 cm (mean 5.3 cm), with an average flap area of 58 cm² (range 24-90). There were no total flap losses, one partial superficial flap loss and one minor donor site delayed healing, over a mean follow-up of 6 months (4-24 months). The average overall patient satisfaction was 91 on Michigan Hand Outcomes Questionnaire. Pain was well tolerated with a low average pain score of 15.

CONCLUSION

The modified arterialised saphenous flow through flap is a useful option for reconstructing the soft tissue defect and reconstituting the radial artery after RFFF harvest.

Using Free Arterialized Venous Flaps for Reconstructing Hand Defects

Hand and digit soft tissue defects are quite common and frequently require specialized reconstruction. When local flaps cannot be used to reconstruct a soft tissue defect, free flaps must be utilized. To overcome tissue volume and discrepancies in vessel diameter, arterialized venous free flaps from the forearm may provide an acceptable alternative. When using arterialized venous free flaps, surgeons should implement shunt restriction procedures to enhance flap viability.

A metabolic investigation of arterialized venous flaps in rabbits using mass spectrometry-based metabolomics

An arterialized venous flap (AVF) is an ideal choice of flap to repair wounds. However, the survival of these flaps remains the source of some concern. This study used metabolomic analysis to investigate the mechanisms underlying survival in AVF flaps in order to guide the clinical application of these flaps. Thirty-six male Japanese rabbits were randomly divided into a sham group and an AVF group. They were used for histology and hemodynamic investigations. Three days after surgery, tissue samples were analyzed by mass spectroscopy-based metabolomics. The results of the study revealed a reduction in blood flow, infiltration of inflammatory cells, and necrosis of flaps in the AVF group. In addition, notable changes were evident in the levels of several metabolites in the AVF group, including lactic acid, acetoacetic acid, inositol phosphate, arachidonic acid, and other metabolites. Our results indicate that the AVF group experienced changes in several biological pathways, including energy metabolism, cell membrane stability, and inflammatory response. There is a significant metabolic difference between AVFs and physiological flaps. The dysregulation in certain metabolites may be related to the specific hemodynamics and insufficient energy metabolism of the AVFs.

Role of Arterial Perfusion in Early Survival of Arterialized Venous Flaps: A Mechanism Study and Clinical Application

BACKGROUND

The arterialized venous flap (AVF) is appropriate as a flap for hand and foot resurfacing meet the aesthetic demands in the same time. However, the inconsistency of survival rate limited its popularization in clinical settings. The purpose of this study was to investigate the role played by the caliber and location of the artery.

METHODS

Arterialized venous flaps were designed on the abdomen of New Zealand rabbits, and the animals were randomized into 3 groups and 2 groups in experiment 1 and 2, respectively. In experiment 1, the artery flow was restricted with vascular staplers of different calibers. In experiment 2, the artery was anastomosed with the afferent vein in the center or at the margin of the flap. Blood perfusion state, water content, epidermal metabolite levels, and flap survival status were observed in both experiments. Furthermore, outcomes of 12 patients received AVF to resurface soft tissue defects in the digits, hands, and feet between January 2016 and February 2018 were analyzed.

RESULTS

In experiment 1, compared with the control group, groups with restricted artery showed poor results regarding blood perfusion state, water content, epidermal metabolite levels, and flap survival status. In experiment 2, group with the afferent vein in the center of the flap showed better results mentioned previously. All the flaps survived uneventfully in this study. Two flaps partially failed (20% of the flap area) because of insufficient perfusion. Generally, larger caliber and center-located vein helped the survival of AVF.

CONCLUSIONS

Experimental findings suggested that increased arterial perfusion and center-located vein are beneficial for the survival of AVF. Clinical series proved the findings previously. The problem of inconsistency of AVF can be partially solved by increasing arterial perfusion and dissecting afferent vein into the center of flap, and still, further studies are needed to shed light on the mechanism behind.

BD-2 and BD-3 increase skin flap survival in a model of ischemia and Pseudomonas aeruginosa infection

The main aim of this work was to study the usefulness of human β-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap survival in the context of a P. aeruginosa infection associated with a foreign body. The secondary endpoints assessed were: bacterial counts, and biofilm formation on the surface of the foreign body. A local ischemic environment was created by producing arterialized venous flaps in the left epigastric region of rats. Flaps were intentionally infected by placing underneath them two catheters with 105 CFU of P. aeruginosa before the surgical wounds were hermetically closed. Flap biopsies were performed 3 and 7 days post-operatively, and the specimens submitted to immunohistochemical analysis for BD-2 and BD-3, as well as to bacterial quantification. Subsequently, the catheter segments were analyzed with scanning electron microscopy (SEM). Flaps transduced with BD-2 and BD-3 showed expression of these defensins and presented increased flap survival. Rats transduced with BD-3 presented a net reduction in the number of P. aeruginosa on the surface of the foreign body and lesser biofilm formation.

Unconventional Perfusion Flaps in the Experimental Setting: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

Background:

Unconventional perfusion flaps offer multiple potential advantages compared with traditional flaps. Although there are numerous experimental articles on unconventional perfusion flaps, the multiple animal species involved, the myriad vascular constructions used, and the frequently conflicting data reported make synthesis of this information challenging. The main aim of this study was to perform a systematic review and meta-analysis of the literature on the experimental use of unconventional perfusion flaps, to identify the best experimental models proposed and to estimate their global survival rate.

Methods:

The authors performed a systematic review and meta-analysis of all articles written in English, French, Italian, Spanish, and Portuguese on the experimental use of unconventional perfusion flaps and indexed to PubMed from 1981 until February 1, 2017.

Results:

A total of 68 studies were found, corresponding to 86 optimized experimental models and 1073 unconventional perfusion flaps. The overall unconventional perfusion flap survival rate was 90.8 percent (95 percent CI, 86.9 to 93.6 percent; p < 0.001). The estimated proportion of experimental unconventional perfusion flaps presenting complete survival or nearly complete survival was 74.4 percent (95 percent CI, 62.1 to 83.7 percent; p < 0.001). The most commonly reported animal species in the literature were the rabbit (57.1 percent), the rat (26.4 percent), and the dog (14.3 percent). No significant differences were found in survival rates among these species, or among the diverse vascular patterns used.

Conclusion:

These data do not differ significantly from those reported regarding the use of unconventional perfusion flaps in human medicine, suggesting that rabbit, rat, and canine experimental unconventional perfusion flap models may adequately mimic the clinical application of unconventional perfusion flaps.

[Repair of soft tissue defect of fingers with modified arterialized venous flap]

OBJECTIVE

To summarize the effectiveness of modified arterialized venous flaps in repairing soft tissue defect of fingers.

METHODS

Between January 2017 and April 2018, 16 patients with soft defects of fingers were treated. There were 12 males and 4 females, with an average age of 41 years (range, 24-74 years). One case was resulted from resection of cicatricial contracture and 15 cases was caused by mechanical strangulation. The defects located at thumb in 3 cases, index finger in 5 cases, middle finger in 4 cases, ring finger in 2 cases, and little finger in 2 cases; and at the palmar aspect in 4 cases, and dorsal aspect in 12 cases. The size of defect ranged from 3 cm×2 cm to 10 cm×3 cm. All flaps were harvested from the palmar aspect of the ipsilateral forearm. The distal ports of the two veins were ligation. Partial fat was eliminated and the all connecting minute branches between the two veins were ligation under microscope in order to achieve the thorough shunt restriction. Then the flaps were positioned over the recipient site without inversion. The size of flap ranged from 3.5 cm×2.5 cm to 10.5 cm×3.5 cm. All donor sites were directly sutured except that 1 case was recovered with free skin graft.

RESULTS

All flaps survived entirely except that 1 case happened vein crisis. Three flaps demonstrated mild-to-moderate venous congestion without any treatment and the swelling of flaps gradually subsided after 1 week. Skin grafting at donor site survived and all incisions healed by first intension. Thirteen patients were followed up 8-16 months (mean, 11 months). The textures and appearances of the flaps were satisfactory. At last follow-up, the mean size of the Semmes-Weinstein (SW) monofilament test of the flaps was 4.01 g (range, 2.83-4.56 g); the mean static two-point discrimination of the flaps was 12 mm (range, 6-20 mm).

CONCLUSION

Modified arterialized venous flaps with thoroughly restriction of arteriovenous shunting can offer decreased congestion of venous flaps and improve survival rate. Better effectiveness can be achieved by using this flap to repair soft tissue defect of finger.

Optimization of an Arterialized Venous Fasciocutaneous Flap in the Abdomen of the Rat

BACKGROUND

Although numerous experimental models of arterialized venous flaps (AVFs) have been proposed, no single model has gained widespread acceptance. The main aim of this work was to evaluate the survival area of AVFs produced with different vascular constructs in the abdomen of the rat.

METHODS

Fifty-three male rats were divided into 4 groups. In group I (n = 12), a 5-cm-long and 3-cm-wide conventional epigastric flap was raised on the left side of the abdomen. This flap was pedicled on the superficial caudal epigastric vessels caudally and on the lateral thoracic vein cranially. In groups II, III, and IV, a similar flap was raised, but the superficial epigastric artery was ligated. In these groups, AVFs were created using the following arterial venous anastomosis at the caudal end of the flap: group II (n = 13) a 1-mm-long side-to-side anastomosis was performed between the femoral artery and vein laterally to the ending of the superficial caudal epigastric vein. In group III (n = 14), in addition to the procedure described for group II, the femoral vein was ligated medially. Finally, in group IV (n = 14), the superficial caudal epigastric vein was cut from the femoral vein with a 1-mm-long ellipse of adjacent tissue, and an end-to-side arterial venous anastomosis was established between it and the femoral artery.

RESULTS

Seven days postoperatively, the percentage of flap survival was 98.89 ± 1.69, 68.84 ± 7.36, 63.84 ± 10.38, 76.86 ± 13.67 in groups I-IV, respectively.

CONCLUSION

An optimized AVF can be produced using the vascular architecture described for group IV.